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  • richardmitnick 8:13 am on September 3, 2017 Permalink | Reply
    Tags: , , , , , Nautilus, Neutron star mergers are the largest hadron colliders ever conceived, , What the Rumored Neutron Star Merger Might Teach Us   

    From Nautilus: “What the Rumored Neutron Star Merger Might Teach Us” 

    Nautilus

    Nautilus

    Aug 29, 2017
    Dan Garisto

    1
    In a sense, neutron star mergers are the largest hadron colliders ever conceived. Image by NASA Goddard Space Flight Center / Flickr

    This month, before LIGO, the Laser Interferometer Gravitational Wave Observatory, and its European counterpart Virgo, were going to close down for a year to undergo upgrades, they jointly surveyed the skies.


    Caltech/MIT Advanced aLigo Hanford, WA, USA installation


    Caltech/MIT Advanced aLigo detector installation Livingston, LA, USA

    Cornell SXS, the Simulating eXtreme Spacetimes (SXS) project


    Gravitational waves. Credit: MPI for Gravitational Physics/W.Benger-Zib

    ESA/eLISA the future of gravitational wave research

    VIRGO Gravitational Wave interferometer, near Pisa, Italy

    It was a small observational window—the 1st to the 25th—but that may have been enough: A rumor that LIGO has detected another gravitational wave—the fourth in two years—is making the rounds. But this time, there’s a twist: The signal might have been caused by the merger of two neutron stars instead of black holes.

    If the rumor holds true, it would be an astonishingly lucky detection. To get a sense of the moment, Nautilus spoke to David Radice, a postdoctoral researcher at Princeton who simulates neutron star mergers, “one of LIGO’s main targets,” he says.

    This potential binary neutron star merger sighting reminds me of when biologists think they’ve discovered a new species. How would you describe it?

    I do agree that this is the first time something like this has been seen.

    For me, a nice analogy is one of particle colliders. In a sense, neutron star mergers are the largest hadron colliders ever conceived. Instead of smashing a few nucleons, it’s like smashing 1060 of them. So by looking at the aftermath, we can learn a lot about fundamental physics. There is a lot that can happen when these stars collide and I don’t think we have a full knowledge of all the possibilities. I think we’ll learn a lot and see new things.

    What it would it mean if they were detecting a neutron star binary merger?

    I expected this neutron star merger to be detected further in the future—the possibility that this merger has been detected earlier suggests that that rate of these events is higher than we thought. There is maybe also a counterpart—an electromagnetic wave. There are many things that you can only really do with an electromagnetic counterpart. For example, even when we have, in the far future, five detectors worldwide, we will not be able to pinpoint the exact location to the source with the precision to say: “OK, this is the host galaxy.”

    Well, if you have an electromagnetic counterpart, especially in the optical region, you can really pinpoint a galaxy and say, “This merger happened in this galaxy that has these properties.”

    What makes a neutron star binary merger different from a black hole binary merger?

    One of the main things is that in a black hole binary merger, you’re just looking at the space-time effects. In this case we are looking at this extremely dense matter. There are a lot of things that you can hope to learn about neutron star mergers. We’re looking at them for a source of gamma ray bursts, or as the origin of heavy elements, or as a way to learn about physics of very high density matter.

    One idea that has been around now for a few years is that many of the heavy elements—elements, for example, like platinum or gold—may actually be produced in neutron star mergers. Material is ejected, and because of nuclear processes, it will produce these heavy elements that are otherwise difficult to produce in normal stars.

    You’ve created visual simulations of neutron star mergers, like the one below. How much power is required to run them?

    It’s publicly available—anyone can download the code and do simulations similar to those…but you need to run them on a supercomputer. It typically takes weeks on thousands of processors, but it can tell you a lot about these mergers. Now the two detectors both LIGO and Virgo are expected to shut down and go through a series of upgrades. When they come back online, their sensitivity will be significantly boosted so we can see much farther out and learn more about each event.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

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  • richardmitnick 11:30 am on August 6, 2017 Permalink | Reply
    Tags: and Why Does It Seem to Flow?, , , China to launch world’s first ‘cold’ atomic clock in space ... and it’ll stay accurate for a billion years., , Nautilus, Where Did Time Come From   

    From Nautilus: “Where Did Time Come From, and Why Does It Seem to Flow?” 

    Nautilus

    Nautilus

    Jul 18, 2017
    John Steele

    1
    We say a river flows because it moves through space with respect to time. But time can’t move with respect to time—time is time.Image by violscraper / Flickr.


    NASA Deep Space Atomic Clock

    1
    NIST-F2 atomic clock operated by America’s National Institute of Standards and Technology in Boulder, Colorado.

    3
    China to launch world’s first ‘cold’ atomic clock in space … and it’ll stay accurate for a billion years.

    Paul Davies has a lot on his mind—or perhaps more accurate to say in his mind. A physicist at Arizona State University, he does research on a wide range of topics, from the abstract fields of theoretical physics and cosmology to the more concrete realm of astrobiology, the study of life in places beyond Earth. Nautilus sat down for a chat with Davies, and the discussion naturally drifted to the subject of time, a long-standing research interest of his. Here is a partial transcript of the interview, edited lightly for length and clarity.

    Is the flow of time real or an illusion?

    The flow of time is an illusion, and I don’t know very many scientists and philosophers who would disagree with that, to be perfectly honest. The reason that it is an illusion is when you stop to think, what does it even mean that time is flowing? When we say something flows like a river, what you mean is an element of the river at one moment is in a different place of an earlier moment. In other words, it moves with respect to time. But time can’t move with respect to time—time is time. A lot of people make the mistake of thinking that the claim that time does not flow means that there is no time, that time does not exist. That’s nonsense. Time of course exists. We measure it with clocks. Clocks don’t measure the flow of time, they measure intervals of time. Of course there are intervals of time between different events; that’s what clocks measure.

    So where does this impression of flow come from?

    Well, I like to give an analogy. Suppose I stand up, twirl around a few times, and stop. Then I have the overwhelming impression that the entire universe is rotating. I feel it to be rotating—of course I know it’s not. In the same way, I feel time is flowing, but of course I know it’s not. And presumably the explanation for this illusion has to do with something up here [in your head] and is connected with memory I guess—laying down of memories and so on. So it’s a feeling we have, but it’s not a property of time itself.

    And the other thing people contemplate: They think denying the flow of time is denying time asymmetry of the world. Of course events in the world follow a directional sequence. Drop an egg on the floor and it breaks. You don’t see eggs assembling themselves. Buildings fall down after earthquakes; they don’t rise up from heaps of rubble. [There are] many, many examples in daily life of the asymmetry of the world in time; that’s a property of the world. It’s not a property of time itself, and the explanation for that is to be sought in the very early universe and its initial conditions. It’s a whole different and perfectly respectable subject.

    Is time fundamental to the Universe?

    Time and space are the framework in which we formulate all of our current theories of the universe, but there is some question as to whether these might be emergent or secondary qualities of the universe. It could be that fundamentally the laws of the universe are formulated in terms of some sort of pre-space and time, and that space-time comes out of something more fundamental.

    Now obviously in daily life we experience a three-dimensional world and one dimension of time. But back in the Big Bang—we don’t really understand exactly how the universe was born in the Big Bang, but we think that quantum physics had something to do with it—it may be that this notion of what we would call a classical space-time, where everything seems to be sort of well-defined, maybe that was all closed out. And so maybe not just the world of matter and energy, but even space-time itself is a product of the special early stage of the universe. We don’t know that. That’s work under investigation.

    So time could be emergent?

    This dichotomy between space-time being emergent, a secondary quality—that something comes out of something more primitive, or something that is at the rock bottom of our description of nature—has been floating around since before my career. John Wheeler believed in and wrote about this in the 1950s—that there might be some pre-geometry, that would give rise to geometry just like atoms give rise to the continuum of elastic bodies—and people play around with that.

    The problem is that we don’t have any sort of experimental hands on that. You can dream up mathematical models that do this for you, but testing them looks to be pretty hopeless. I think the reason for that is that most people feel that if there is anything funny sort of underpinning space and time, any departure from our notion of a continuous space and time, that probably it would manifest itself only at the so-called Planck scale, which is [20 orders of magnitude] smaller than an atomic nucleus, and our best instruments at the moment are probing scales which are many orders of magnitude above that. It’s very hard to see how we could get at anything at the Planck scale in a controllable way.

    If multiple universes exist, do they have a common clock?

    The inter-comparison of time between different observers and different places is a delicate business even within one universe. When you talk about what is the rate of a clock, say, near the surface of a black hole, it’s going to be quite different from the rate of a clock here on Earth. So there isn’t even a common time in the entire universe.

    But now if we have a multiverse with other universes, whether each one in a sense comes with its own time—you can only do an inter-comparison between the two if there was some way of sending signals from one to the other. It depends on your multiverse model. There are many on offer, but on the one that cosmologists often talk about—where you have bubbles appearing in a sort of an inflating superstructure—then there’s no direct way of comparing a clock rate in one bubble from clock rates in another bubble.

    What do you think are the most exciting recent advances in understanding time?

    I’m particularly drawn to the work that is done in the lab on perception of time, because I think that has the ability to make rapid advances in the coming years. For example, there are famous experiments in which people apparently make free decisions at certain moments and yet it’s found that the decision was actually made a little bit earlier, but their own perception of time and their actions within time have been sort of edited after the event. When we observe the world, what we see is an apparently consistent and smooth narrative, but actually the brain is just being bombarded with sense data from different senses and puts all this together. It integrates it and then presents a consistent narrative as it were the conscious self. And so we have this impression that we’re in charge and everything is all smoothly put together. But as a matter of fact, most of this is, is a narrative that’s recreated after the event.

    Where it’s particularly striking of course is when people respond appropriately much faster than the speed of thought. You need only think of a piano player or a tennis player to see that the impression that they are making a conscious decision—“that ball is coming in this direction; I’d better move over here and hit it”—couldn’t possibly be. The time it takes for the signals to get to the brain and then through the motor system, back to the response, couldn’t work. And yet they still have this overwhelming impression that they’re observing the world in real time and are in control. I think all of this is pretty fascinating stuff.

    In terms of fundamental physics, is there anything especially new about time? I think the answer is not really. There are new ideas that are out there. I think there are still fundamental problems; we’ve talked about one of them: Is time an emergent property or a fundamental property? And the ultimate origin of the arrow of time, which is the asymmetry of the world in time, is still a bit contentious. We know we have to trace it back to the Big Bang, but there are still different issues swirling around there that we haven’t completely resolved. But these are sort of airy-fairy philosophical and theoretical issues in terms of measurement of time or anything being exposed about the nature of time.

    Then of course we’re always looking to our experimental colleagues to improve time measurements. At some stage these will become so good that we’ll no doubt see some peculiar effects showing up. There’s still an outstanding fundamental issue that although the laws of physics are symmetric in time, for the most part, there is one set of processes having to do with the weak interaction where there is apparently a fundamental breakdown of this time-reversal symmetry of a small amount. But it seems to play a crucial role and exactly how that fits into the broader picture in the universe. I think there’s still something to be played out there. So there’s still experiments can be done in particle physics that might disclose this time-reversal asymmetry which is there in the weak interaction, and how that fits in with the arrow of time.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

     
  • richardmitnick 7:46 am on June 15, 2017 Permalink | Reply
    Tags: , , , Nautilus, When Neurology Becomes Theology, Wilder Penfield   

    From Nautilus: “When Neurology Becomes Theology” 

    Nautilus

    Nautilus

    June 15, 2017
    Robert A. Burton

    A neurologist’s perspective on research into consciousness.

    Early in my neurology residency, a 50-year-old woman insisted on being hospitalized for protection from the FBI spying on her via the TV set in her bedroom. The woman’s physical examination, lab tests, EEGs, scans, and formal neuropsychological testing revealed nothing unusual. Other than being visibly terrified of the TV monitor in the ward solarium, she had no other psychiatric symptoms or past psychiatric history. Neither did anyone else in her family, though she had no recollection of her mother, who had died when the patient was only 2.

    The psychiatry consultant favored the early childhood loss of her mother as a potential cause of a mid-life major depressive reaction. The attending neurologist was suspicious of an as yet undetectable degenerative brain disease, though he couldn’t be more specific. We residents were equally divided between the two possibilities.

    Fortunately an intern, a super-sleuth more interested in data than speculation, was able to locate her parents’ death certificates. The patient’s mother had died in a state hospital of Huntington’s disease—a genetic degenerative brain disease. (At that time such illnesses were often kept secret from the rest of the family.) Case solved. The patient was a textbook example of psychotic behavior preceding the cognitive decline and movement disorders characteristic of Huntington’s disease.

    1
    WHERE’S THE MIND?: Wilder Penfield spent decades studying how brains produce the experience of consciousness, but concluded “There is no good evidence, in spite of new methods, that the brain alone can carry out the work that the mind does.” Montreal Neurological Institute

    As a fledgling neurologist, I’d already seen a wide variety of strange mental states arising out of physical diseases. But on this particular day, I couldn’t wrap my mind around a gene mutation generating an isolated feeling of being spied on by the FBI. How could a localized excess of amino acids in a segment of DNA be transformed into paranoia?

    Though I didn’t know it at the time, I had run headlong into the “hard problem of consciousness,” the enigma of how physical brain mechanisms create purely subjective mental states. In the subsequent 50 years, what was once fodder for neurologists’ late night speculations has mushroomed into the pre-eminent question in the philosophy of mind. As an intellectual challenge, there is no equal to wondering how subatomic particles, mindless cells, synapses, and neurotransmitters create the experience of red, the beauty of a sunset, the euphoria of lust, the transcendence of music, or in this case, intractable paranoia.

    Neuroscientists have long known which general areas of the brain and their connections are necessary for the state of consciousness. By observing both the effects of localized and generalized brain insults such as anoxia and anesthesia, none of us seriously doubt that consciousness arises from discrete brain mechanisms. Because these mechanisms are consistent with general biological principles, it’s likely that, with further technical advances, we will uncover how the brain generates consciousness.

    However, such knowledge doesn’t translate into an explanation for the what of consciousness—that state of awareness of one’s surroundings and self, the experience of one’s feelings and thoughts. Imagine a hypothetical where you could mix nine parts oxytocin, 17 parts serotonin, and 11 parts dopamine into a solution that would make 100 percent of people feel a sense of infatuation 100 percent of the time. Knowing the precise chemical trigger for the sensation of infatuation (the how) tells you little about the nature of the resulting feeling (the what).

    Over my career, I’ve gathered a neurologist’s working knowledge of the physiology of sensations. I realize neuroscientists have identified neural correlates for emotional responses. Yet I remain ignorant of what sensations and responses are at the level of experience. I know the brain creates a sense of self, but that tells me little about the nature of the sensation of “I-ness.” If the self is a brain-generated construct, I’m still left wondering who or what is experiencing the illusion of being me. Similarly, if the feeling of agency is an illusion, as some philosophers of mind insist, that doesn’t help me understand the essence of my experience of willfully typing this sentence.

    Slowly, and with much resistance, it’s dawned on me that the pursuit of the nature of consciousness, no matter how cleverly couched in scientific language, is more like metaphysics and theology. It is driven by the same urges that made us dream up gods and demons, souls and afterlife. The human urge to understand ourselves is eternal, and how we frame our musings always depends upon prevailing cultural mythology. In a scientific era, we should expect philosophical and theological ruminations to be couched in the language of physical processes. We argue by inference and analogy, dragging explanations from other areas of science such as quantum physics, complexity, information theory, and math into a subjective domain. Theories of consciousness are how we wish to see ourselves in the world, and how we wish the world might be.

    My first hint of the interaction between religious feelings and theories of consciousness came from Montreal Neurological Institute neurosurgeon Wilder Penfield’s 1975 book, Mystery of the Mind: A Critical Study of Consciousness and the Human Brain. One of the great men of modern neuroscience, Penfield spent several decades stimulating the brains of conscious, non-anesthetized patients and noting their descriptions of the resulting mental states, including long-lost bits of memory, dreamy states, deju vu, feelings of strangeness, and otherworldliness. What was most startling about Penfield’s work was his demonstration that sensations that normally qualify how we feel about our thoughts can occur in the absence of any conscious thought. For example, he could elicit feelings of familiarity and strangeness without the patient thinking of anything to which the feeling might apply. His ability to spontaneously evoke pure mental states was proof positive that these states arise from basic brain mechanisms.

    And yet, here’s Penfield’s conclusion to his end-of-career magnum opus on the nature of the mind: “There is no good evidence, in spite of new methods, that the brain alone can carry out the work that the mind does.” How is this possible? How could a man who had single-handedly elicited so much of the fabric of subjective states of mind decide that there was something to the mind beyond what the brain did?

    In the last paragraph of his book, Penfield explains, “In ordinary conversation, the ‘mind’ and ‘the spirit of man’ are taken to be the same. I was brought up in a Christian family and I have always believed, since I first considered the matter … that there is a grand design in which all conscious individuals play a role … Since a final conclusion … is not likely to come before the youngest reader of this book dies, it behooves each one of us to adopt for himself a personal assumption (belief, religion), and a way of life without waiting for a final word from science on the nature of man’s mind.”

    Front and center is Penfield’s observation that, in ordinary conversation, the mind is synonymous with the spirit of man. Further, he admits that, in the absence of scientific evidence, all opinions about the mind are in the realm of belief and religion. If Penfield is even partially correct, we shouldn’t be surprised that any theory of the “what” of consciousness would be either intentionally or subliminally infused with one’s metaphysics and religious beliefs.

    To see how this might work, take a page from Penfield’s brain stimulation studies where he demonstrates that the mental sensations of consciousness can occur independently from any thought that they seem to qualify. For instance, conceptualize thought as a mental calculation and a visceral sense of the calculation. If you add 3 + 3, you compute 6, and simultaneously have the feeling that 6 is the correct answer. Thoughts feel right, wrong, strange, beautiful, wondrous, reasonable, far-fetched, brilliant, or stupid. Collectively these widely disparate mental sensations constitute much of the contents of consciousness. But we have no control over the mental sensations that color our thoughts. No one can will a sense of understanding or the joy of an a-ha! moment. We don’t tell ourselves to make an idea feel appealing; it just is. Yet these sensations determine the direction of our thoughts. If a thought feels irrelevant, we ignore it. If it feels promising, we pursue it. Our lines of reasoning are predicated upon how thoughts feel.

    2
    No image caption or credit.

    Shortly after reading Penfield’s book, I had the good fortune to spend a weekend with theoretical physicist David Bohm. Bohm took a great deal of time arguing for a deeper and interconnected hidden reality (his theory of implicate order). Though I had difficulty following his quantum theory-based explanations, I vividly remember him advising me that the present-day scientific approach of studying parts rather than the whole could never lead to any final answers about the nature of consciousness. According to him, all is inseparable and no part can be examined in isolation.

    In an interview in which he was asked to justify his unorthodox view of scientific method, Bohm responded, “My own interest in science is not entirely separate from what is behind an interest in religion or in philosophy—that is to understand the whole of the universe, the whole of matter, and how we originate.” If we were reading Bohm’s argument as a literary text, we would factor in his Jewish upbringing, his tragic mistreatment during the McCarthy era, the lack of general acceptance of his idiosyncratic take on quantum physics, his bouts of depression, and the close relationship between his scientific and religious interests.

    Many of today’s myriad explanations for how consciousness arises are compelling. But once we enter the arena of the nature of consciousness, there are no outright winners.

    Christof Koch, the chief scientific officer of the Allen Institute for Brain Science in Seattle, explains that a “system is conscious if there’s a certain type of complexity. And we live in a universe where certain systems have consciousness. It’s inherent in the design of the universe.”

    According to Daniel Dennett, professor of philosophy at Tufts University and author of Consciousness Explained and many other books on science and philosophy, consciousness is nothing more than a “user-illusion” arising out of underlying brain mechanisms. He argues that believing consciousness plays a major role in our thoughts and actions is the biological equivalent of being duped into believing that the icons of a smartphone app are doing the work of the underlying computer programs represented by the icons. He feels no need to postulate any additional physical component to explain the intrinsic qualities of our subjective experience.

    Meanwhile, Max Tegmark, a theoretical physicist at the Massachusetts Institute of Technology, tells us consciousness “is how information feels when it is being processed in certain very complex ways.” He writes that “external reality is completely described by mathematics. If everything is mathematical, then, in principle, everything is understandable.” Rudolph E. Tanzi, a professor of neurology at Harvard University, admits, “To me the primal basis of existence is awareness and everything including ourselves and our brains are products of awareness.” He adds, “As a responsible scientist, one hypothesis which should be tested is that memory is stored outside the brain in a sea of consciousness.”

    Each argument, taken in isolation, seems logical, internally consistent, yet is at odds with the others. For me, the thread that connects these disparate viewpoints isn’t logic and evidence, but their overall intent. Belief without evidence is Richard Dawkins’ idea of faith. “Faith is belief in spite of, even perhaps because of, the lack of evidence.” These arguments are best read as differing expressions of personal faith.

    For his part, Dennett is an outspoken atheist and fervent critic of the excesses of religion. “I have absolutely no doubt that secular and scientific vision is right and deserves to be endorsed by everybody, and as we have seen over the last few thousand years, superstitious and religious doctrines will just have to give way.” As the basic premise of atheism is to deny that for which there is no objective evidence, he is forced to avoid directly considering the nature of purely subjective phenomena. Instead he settles on describing the contents of consciousness as illusions, resulting in the circularity of using the definition of mental states (illusions) to describe the general nature of these states.

    The problem compounds itself. Dennett is fond of pointing out (correctly) that there is no physical manifestation of “I,” no ghost in the machine or little homunculus that witnesses and experiences the goings on in the brain. If so, we’re still faced with asking what/who, if anything, is experiencing consciousness? All roads lead back to the hard problem of consciousness.

    Though tacitly agreeing with those who contend that we don’t yet understand the nature of consciousness, Dennett argues that we are making progress. “We haven’t yet succeeded in fully conceiving how meaning could exist in a material world … or how consciousness works, but we’ve made progress: The questions we’re posing and addressing now are better than the questions of yesteryear. We’re hot on the trail of the answers.”

    By contrast, Koch is upfront in correlating his religious upbringing with his life-long pursuit of the nature of consciousness. Raised as a Catholic, he describes being torn between two contradictory views of the world—the Sunday view reflected by his family and church, and the weekday view as reflected in his work as a scientist (the sacred and the profane).

    In an interview with Nautilus, Koch said, “For reasons I don’t understand and don’t comprehend, I find myself in a universe that had to become conscious, reflecting upon itself.” He added, “The God I now believe in is closer to the God of Spinoza than it is to Michelangelo’s paintings or the God of the Old Testament, a god that resides in this mystical notion of all-nothingness.” Koch admitted, “I’m not a mystic. I’m a scientist, but this is a feeling I have.” In short, Koch exemplifies a truth seldom admitted—that mental states such as a mystical feeling shape how one thinks about and goes about studying the universe, including mental states such as consciousness.

    Both Dennett and Koch have spent a lifetime considering the problem of consciousness; though contradictory, each point of view has a separate appeal. And I appreciate much of Dennett and Koch’s explorations in the same way that I can mull over Aquinas and Spinoza without necessarily agreeing with them. One can enjoy the pursuit without believing in or expecting answers. After all these years without any personal progress, I remain moved by the essential nature of the quest, even if it translates into Sisyphus endlessly pushing his rock up the hill.

    The spectacular advances of modern science have generated a mindset that makes potential limits to scientific inquiry intuitively difficult to grasp. Again and again we are given examples of seemingly insurmountable problems that yield to previously unimaginable answers. Just as some physicists believe we will one day have a Theory of Everything, many cognitive scientists believe that consciousness, like any physical property, can be unraveled. Overlooked in this optimism is the ultimate barrier: The nature of consciousness is in the mind of the beholder, not in the eye of the observer.

    It is likely that science will tell us how consciousness occurs. But that’s it. Although the what of consciousness is beyond direct inquiry, the urge to explain will persist. It is who we are and what we do.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

     
  • richardmitnick 9:30 am on June 8, 2017 Permalink | Reply
    Tags: , , , , , Ludwig Boltzmann, Microstates, Nautilus, , , The Crisis of the Multiverse   

    From Nautilus: “The Crisis of the Multiverse” 

    Nautilus

    Nautilus

    June 8, 2017
    Ben Freivogel

    Physicists have always hoped that once we understood the fundamental laws of physics, they would make unambiguous predictions for physical quantities. We imagined that the underlying physical laws would explain why the mass of the Higgs particle must be 125 gigaelectron-volts, as was recently discovered, and not any other value, and also make predictions for new particles that are yet to be discovered.

    CERN CMS Higgs Event

    CERN ATLAS Higgs Event

    For example, we would like to predict what kind of particles make up the dark matter.

    These hopes now appear to have been hopelessly naïve. Our most promising fundamental theory, string theory, does not make unique predictions. It seems to contain a vast landscape of solutions, or “vacua,” each with its own values of the observable physical constants. The vacua are all physically realized within an enormous eternally inflating multiverse.

    Has the theory lost its mooring to observation? If the multiverse is large and diverse enough to contain some regions where dark matter is made out of light particles and other regions where dark matter is made out of heavy particles, how could we possibly predict which one we should see in our own region? And indeed many people have criticized the multiverse concept on just these grounds. If a theory makes no predictions, it ceases to be physics.

    But an important issue tends to go unnoticed in debates over the multiverse. Cosmology has always faced a problem of making predictions. The reason is that all our theories in physics are dynamical: The fundamental physical laws describe what will happen, given what already is. So, whenever we make a prediction in physics, we need to specify what the initial conditions are. How do we do that for the entire universe? What sets the initial initial conditions? This is science’s version of the old philosophical question of First Cause.

    The multiverse offers an answer. It is not the enemy of prediction, but its friend.

    The main idea is to make probabilistic predictions. By calculating what happens frequently and what happens rarely in the multiverse, we can make statistical predictions for what we will observe. This is not a new situation in physics. We understand an ordinary box of gas in the same way. Although we cannot possibly keep track of the motion of all the individual molecules, we can make extremely precise predictions for how the gas as a whole will behave. Our job is to develop a similar statistical understanding of events in the multiverse.

    This understanding could take one of three forms. First, the multiverse, though very large, might be able to explore only a finite number of different states, just like an ordinary box of gas. In this case we know how to make predictions, because after a while the multiverse forgets about the unknown initial conditions. Second, perhaps the multiverse is able to explore an infinite number of different states, in which case it never forgets its initial conditions, and we cannot make predictions unless we know what those conditions are. Finally, the multiverse might explore an infinite number of different states, but the exponential expansion of space effectively erases the initial conditions.

    1
    NEVER ENOUGH TIME: Synchronizing clocks is impossible to do in an infinite universe, which in turn undercuts the ability of physics to make predictions. Matteo Ianeselli / Wikimedia Commons

    In many ways, the first option is the most agreeable to physicists, because it extends our well-established statistical techniques. Unfortunately, the predictions we arrive at disagree violently with observations. The second option is very troubling, because our existing laws are incapable of providing the requisite initial conditions. It is the third possibility that holds the most promise for yielding sensible predictions.

    But this program has encountered severe conceptual obstacles. At root, our problems arise because the multiverse is an infinite expanse of space and time. These infinities lead to paradoxes and puzzles wherever we turn. We will need a revolution in our understanding of physics in order to make sense of the multiverse.

    The first option for making statistical predictions in cosmology goes back to a paper by the Austrian physicist Ludwig Boltzmann in 1895. Although it turns out to be wrong, in its failure we find the roots of our current predicament.

    Boltzmann’s proposal was a bold extrapolation from his work on understanding gases. To specify completely the state of a gas would require specifying the exact position of every molecule. That is impossible. Instead, what we can measure—and would like to make predictions for—is the coarse-grained properties of the box of gas, such as the temperature and the pressure.

    A key simplification allows us to do this. As the molecules bounce around, they will arrange and rearrange themselves in every possible way they can, thus exploring all their possible configurations, or “microstates.” This process will erase the memory of how the gas started out, allowing us to ignore the problem of initial conditions. Since we can’t keep track of where all the molecules are, and anyway their positions change with time, we assume that any microstate is equally likely.

    This gives us a way to calculate how likely it is to find the box in a given coarse-grained state, or “macrostate”: We simply count the fraction of microstates consistent with what we know about the macrostate. So, for example, it is more likely that the gas is spread uniformly throughout the box rather than clumped in one corner, because only very special microstates have all of the gas molecules in one region of the box.

    For this procedure to work, the total number of microstates, while very large, must be finite. Otherwise the system will never be able to explore all its states. In a box of gas, this finitude is guaranteed by the uncertainty principle of quantum mechanics. Because the position of each molecule cannot be specified exactly, the gas has only a finite number of distinct configurations.

    Gases that start off clumpy for some reason will spread out, for a simple reason: It is statistically far more likely for their molecules to be uniformly distributed rather than clustered. If the molecules begin in a fairly improbable configuration, they will naturally evolve to a more probable one as they bounce around randomly.

    Yet our intuition about gases must be altered when we consider huge spans of time. If we leave the gas in the box for long enough, it will explore some unusual microstates. Eventually all of the particles will accidentally cluster in one corner of the box.

    With this insight, Boltzmann launched into his cosmological speculations. Our universe is intricately structured, so it is analogous to a gas that clusters in one corner of a box—a state that is far from equilibrium. Cosmologists generally assume it must have begun that way, but Boltzmann pointed out that, over the vastness of the eons, even a chaotic universe will randomly fluctuate into a highly ordered state. Attributing the idea to his assistant, known to history only as “Dr. Schuetz,” Boltzmann wrote:

    “It may be said that the world is so far from thermal equilibrium that we cannot imagine the improbability of such a state. But can we imagine, on the other side, how small a part of the whole universe this world is? Assuming the universe is great enough, the probability that such a small part of it as our world should be in its present state, is no longer small.”

    “If this assumption were correct, our world would return more and more to thermal equilibrium; but because the whole universe is so great, it might be probable that at some future time some other world might deviate as far from thermal equilibrium as our world does at present.”

    It is a compelling idea. What a shame that it is wrong.

    The trouble was first pointed out by the astronomer and physicist Sir Arthur Eddington in 1931, if not earlier. It has to do with what are now called “Boltzmann brains.” Suppose the universe is like a box of gas and, most of the time, is in thermal equilibrium—just a uniform, undifferentiated gruel. Complex structures, including life, arise only when there are weird fluctuations. At these moments, gas assembles into stars, our solar system, and all the rest. There is no step-by-step process that sculpts it. It is like a swirling cloud that, all of a sudden, just so happens to take the shape of a person.

    The problem is a quantitative one. A small fluctuation that makes an ordered structure in a small part of space is far, far more likely than a large fluctuation that forms ordered structures over a huge region of space. In Boltzmann and Schuetz’s theory, it would be far, far more likely to produce our solar system without bothering to make all of the other stars in the universe. Therefore, the theory conflicts with observation: It predicts that typical observers should see a completely blank sky, without stars, when they look up at night.

    Taking this argument to an extreme, the most common type of observer in this theory is one that requires the minimal fluctuation away from equilibrium. We imagine this as an isolated brain that survives just long enough to notice it is about to die: the so-called Boltzmann brain.

    If you take this type of theory seriously, it predicts that we are just some very special Boltzmann brains who have been deluded into thinking that we are observing a vast, homogeneous universe. At the next instant our delusions are extremely likely to be shattered, and we will discover that there are no other stars in the universe. If our state of delusion lasts long enough for this article to appear, you can safely discard the theory.

    What are we to conclude? Evidently, the whole universe is not like a box of gas after all. A crucial assumption in Boltzmann’s argument is that there are only a finite (if very large) number of molecular configurations. This assumption must be incorrect. Otherwise, we would be Boltzmann brains.

    2
    DON’T WAKE ME UP: Hibernation thought-experiments reveal a deep paradox with probability in an infinite multiverse. Twentieth Century Fox-Film Corporation / Photofest

    So, we must seek a new approach to making predictions in cosmology. The second option on our list is that the universe has an infinite number of states available to it. Then the tools that Boltzmann developed are no longer useful in calculating the probability of different things happening.

    But then we’re back to the problem of initial conditions. Unlike a finite box of gas, which forgets about its initial conditions as the molecules scramble themselves, a system with an infinite number of available states cannot forget its initial conditions, because it takes an infinite time to explore all of its available states. To make predictions, we would need a theory of initial conditions. Right now, we don’t have one. Whereas our present theories take the prior state of the universe as an input, a theory of initial conditions would have to give this state as an output. It would thus require a profound shift in the way physicists think.

    The multiverse offers a third way—that is part of its appeal. It allows us to make cosmological predictions in a statistical way within the current theoretical framework of physics. In the multiverse, the volume of space grows indefinitely, all the while producing expanding bubbles with a variety of states inside. Crucially, the predictions do not depend on the initial conditions. The expansion approaches a steady-state behavior, with the expanding high-energy state continually expanding and budding off lower-energy regions. The overall volume of space is growing, and the number of bubbles of every type is growing, but the ratio (and the probabilities) remain fixed.

    The basic idea of how to make predictions in such a theory is simple. We count how many observers in the multiverse measure a physical quantity to have a given value. The probability of our observing a given outcome equals the proportion of observers in the multiverse who observe that outcome.

    For instance, if 10 percent of observers live in regions of the multiverse where dark matter is made out of light particles (such as axions), while 90 percent of observers live in regions where dark matter is made out of heavy particles (which, counterintuitively, are called WIMPs), then we have a 10 percent chance of discovering that dark matter is made of light particles.

    The very best reason to believe this type of argument is that Steven Weinberg of the University of Texas at Austin used it to successfully predict the value of the cosmological constant a decade before it was observed. The combination of a theoretically convincing motivation with Weinberg’s remarkable success made the multiverse idea attractive enough that a number of researchers, including me, have spent years trying to work it out in detail.

    The major problem we faced is that, since the volume of space grows without bound, the number of observers observing any given thing is infinite, making it difficult to characterize which events are more or less likely to occur. This amounts to an ambiguity in how to characterize the steady-state behavior, known as the measure problem.

    Roughly, the procedure to make predictions goes as follows. We imagine that the universe evolves for a large but finite amount of time and count all of the observations. Then we calculate what happens when the time becomes arbitrarily large. That should tell us the steady-state behavior. The trouble is that there is no unique way to do this, because there is no universal way to define a moment in time. Observers in distant parts of spacetime are too far apart and accelerating away from each other too fast to be able to send signals to each other, so they cannot synchronize their clocks. Mathematically, we can choose many different conceivable ways to synchronize clocks across these large regions of space, and these different choices lead to different predictions for what types of observations are likely or unlikely.

    One prescription for synchronizing clocks tells us that most of the volume will be taken up by the state that expands the fastest. Another tells us that most of the volume will be taken up by the state the decays the slowest. Worse, many of these prescriptions predict that the vast majority of observers are Boltzmann brains. A problem we thought we had eliminated came rushing back in.

    When Don Page at the University of Alberta pointed out the potential problems with Boltzmann brains in a paper in 2006, Raphael Bousso at U.C. Berkeley and I were thrilled to realize that we could turn the problem on its head. We found we could use Boltzmann brains as a tool—a way to decide among differing prescriptions for how to synchronize clocks. Any proposal that predicts that we are Boltzmann brains must perforce be wrong. We were so excited (and worried that someone else would have the same idea) that we wrote our paper in just two days after Page’s paper appeared. Over the course of several years, persistent work by a relatively small group of researchers succeeded in using these types of tests to eliminate many proposals and to form something of a consensus in the field on a nearly unique solution to the measure problem. We felt that we had learned how to tame the frightening infinities of the theory.

    Just when things were looking good, we encountered a conceptual problem that I see no escape from within our current understanding: the end-of-time problem. Put simply, the theory predicts that the universe is on the verge of self-destruction.

    The issue came into focus via a thought experiment suggested by Alan Guth of the Massachusetts Institute of Technology and Vitaly Vanchurin at the University of Michigan in Duluth. This experiment is unusual even by the standards of theoretical physics. Suppose that you flip a coin and do not see the result. Then you are put into a cryogenic freezer. If the coin came up heads, the experimenters wake you up after one year. If the coin came up tails, the experimenters instruct their descendants to wake you up after 50 billion years. Now suppose you have just woken up and have a chance to bet whether you have been asleep for 1 year or 50 billion years. Common sense tells us that the odds for such a bet should be 50/50 if the coin is fair.

    But when we apply our rules for how to do calculations in an eternally expanding universe, we find that you should bet that you only slept for one year. This strange effect occurs because the volume of space is exponentially expanding and never stops. So the number of sleeper experiments beginning at any given time is always increasing. A lot more experiments started a year ago than 50 billion years ago, so most of the people waking up today were asleep for a short time.

    The scenario may sound extreme, even silly. But that’s just because the conditions we are dealing with in cosmology are extreme, involving spans of times and volumes of space that are outside human experience. You can understand the problem by thinking about a simpler scenario that is mathematically identical. Suppose that the population of Earth doubles every 30 years—forever. From time to time, people perform these sleeper experiments, except now the subjects sleep either for 1 year or for 100 years. Suppose that every day 1 percent of the population takes part.

    Now suppose you are just waking up in your cryogenic freezer and are asked to bet how long you were asleep. On the one hand, you might argue that obviously the odds are 50/50. On the other, on any given day, far more people wake up from short naps than from long naps. For example, in the year 2016, sleepers who went to sleep for a short time in 2015 will wake up, as will sleepers who began a long nap in 1916. But since far more people started the experiment in 2015 than in 1916 (always 1 percent of the population), the vast majority of people who wake up in 2016 slept for a short time. So it might be natural to guess that you are waking from a short nap.

    The fact that two logical lines of argument yield contradictory answers tells us that the problem is not well-defined. It just isn’t a sensible problem to calculate probabilities under the assumption that the human population grows exponentially forever, and indeed it is impossible for the population to grow forever. What is needed in this case is some additional information about how the exponential growth stops.

    Consider two options. In the first, one day no more babies are born, but every sleeper experiment that has begun eventually finishes. In the second, a huge meteor suddenly destroys the planet, terminating all sleeper experiments. You will find that in option one, half of all observers who ever wake up do so from short naps, while in option two, most observers who ever wake up do so from short naps. It’s dangerous to take a long nap in the second option, because you might be killed by a meteor while sleeping. Therefore, when you wake up, it’s reasonable to bet that you most likely took a short nap. Once the theory becomes well-defined by making the total number of people finite, probability questions have unique, sensible answers.

    In eternal expansion, more sleepers wake up from short naps. Bousso, Stefan Leichenauer at Berkeley, Vladimir Rosenhaus at the Kavli Institute for Theoretical Physics, and I pointed out that these strange results have a simple physical interpretation: The reason that more sleepers wake up from short naps is that living in an eternally expanding universe is dangerous, because one can run into the end of time. Once we realized this, it became clear that this end-of-time effect was an inherent characteristic of the recipe we were using to calculate probabilities, and it is there whether or not anyone actually decides to undertake these strange sleeper experiments. In fact, given the parameters that define our universe, we calculated that there is about a 50 percent probability of encountering the end of time in the next 5 billion years.

    To be clear about the conclusion: No one thinks that time suddenly ends in spacetimes like ours, let alone that we should be conducting peculiar hibernation experiments. Instead, the point is that our recipe for calculating probabilities accidentally injected a novel type of catastrophe into the theory. This problem indicates that we are missing major pieces in our understanding of physics over large distances and long times.

    To put it all together: Theoretical and observational evidence suggests that we are living in an enormous, eternally expanding multiverse where the constants of nature vary from place to place. In this context, we can only make statistical predictions.

    If the universe, like a box of gas, can exist in only a finite number of available states, theory predicts that we are Boltzmann brains, which conflicts with observations, not to mention common sense. If, on the contrary, the universe has an infinite number of available states, then our usual statistical techniques are not predictive, and we are stuck. The multiverse appears to offer a middle way. The universe has an infinite number of states available, avoiding the Boltzmann brain problem, yet approaches a steady-state behavior, allowing for a straightforward statistical analysis. But then we still find ourselves making absurd predictions. In order to make any of these three options work, I think we will need a revolutionary advance in our understanding of physics.

    See the full article here .

    Please help promote STEM in your local schools.

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    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

     
  • richardmitnick 9:08 am on June 8, 2017 Permalink | Reply
    Tags: , , Craig Kaplan, Johnson solids, Nautilus, Polygons, The Impossible Mathematics of the Real World   

    From Nautilus: “The Impossible Mathematics of the Real World” 

    Nautilus

    Nautilus

    June 8, 2017
    Evelyn Lamb

    Using stiff paper and transparent tape, Craig Kaplan assembles a beautiful roundish shape that looks like a Buckminster Fuller creation or a fancy new kind of soccer ball. It consists of four regular dodecagons (12-sided polygons with all angles and sides the same) and 12 decagons (10-sided), with 28 little gaps in the shape of equilateral triangles. There’s just one problem. This figure should be impossible. That set of polygons won’t meet at the vertices. The shape can’t close up.

    Kaplan’s model works only because of the wiggle room you get when you assemble it with paper. The sides can warp a little bit, almost imperceptibly. “The fudge factor that arises just from working in the real world with paper means that things that ought to be impossible actually aren’t,” says Kaplan, a computer scientist at the University of Waterloo in Canada.

    1
    Impossibly real: This shape, which mathematician Craig Kaplan built using paper polygons, is only able to close because of subtle warping of the paper. Craig Kaplan

    It is a new example of an unexpected class of mathematical objects that the American mathematician Norman Johnson stumbled upon in the 1960s. Johnson was working to complete a project started over 2,000 years earlier by Plato: to catalog geometric perfection. Among the infinite variety of three-dimensional shapes, just five can be constructed out of identical regular polygons: the tetrahedron, cube, octahedron, dodecahedron, and icosahedron. If you mix and match polygons, you can form another 13 shapes from regular polygons that meet the same way at every vertex—the Archimedean solids—as well as prisms (two identical polygons connected by squares) and “anti-prisms” (two identical polygons connected by equilateral triangles).

    In 1966 Johnson, then at Michigan State University, found another 92 solids composed only of regular polygons, now called the Johnson solids. And with that, he exhausted all the possibilities, as the Russian mathematician Viktor Zalgaller, then at Leningrad State University, proved a few years later. It is impossible to form any other closed shapes out of regular polygons.

    Yet in completing the inventory of polyhedra, Johnson noticed something odd. He discovered his shapes by building models from cardboard and rubber bands. Because there are relatively few possible polyhedra, he expected that any new ones would quickly reveal themselves. Once he started to put the sides into place, the shape should click together as a matter of necessity. But that didn’t happen. “It wasn’t always obvious, when you assembled a bunch of polygons, that what was assembled was a legitimate figure,” Johnson recalls.

    A model could appear to fit together, but “if you did some calculations, you could see that it didn’t quite stand up,” he says. On closer inspection, what had seemed like a square wasn’t quite a square, or one of the faces didn’t quite lie flat. If you trimmed the faces, they would fit together exactly, but then they’d no longer be exactly regular.

    Intent on enumerating the perfect solids, Johnson didn’t give these near misses much attention. “I sort of set them aside and concentrated on the ones that were valid,” he says. But not only does this niggling near-perfection draw the interest of Kaplan and other math enthusiasts today, it is part of a large class of near-miss mathematics.

    There’s no precise definition of a near miss. There can’t be. A hard and fast rule doesn’t make sense in the wobbly real world. For now, Kaplan relies on a rule of thumb when looking for new near-miss Johnson solids: “the real, mathematical error inherent in the solid is comparable to the practical error that comes from working with real-world materials and your imperfect hands.” In other words, if you succeed in building an impossible polyhedron—if it’s so close to being possible that you can fudge it—then that polyhedron is a near miss. In other parts of mathematics, a near miss is something that is close enough to surprise or fool you, a mathematical joke or prank.

    Some mathematical near misses are, like near-miss Johnson solids, little more than curiosities, while others have deeper significance for mathematics and physics.

    he ancient problems of squaring the circle and doubling the cube both fall under the umbrella of near misses. They look tantalizingly open to solution, but ultimately prove impossible, like a geometric figure that seems as though it must close, but can’t. Some of the compass-and-straight-edge constructions by Leonardo da Vinci and Albrecht Dürer fudged the angles, producing nearly regular pentagons rather than the real thing.

    2
    Shell game: When the top shape is cut up into four pieces and rearranged, a gap appears, due to warping. Wikipedia

    Then there’s the missing-square puzzle. In this one (above), a right triangle is cut up into four pieces. When the pieces are rearranged, a gap appears. Where’d it come from? It’s a near miss. Neither “triangle” is really a triangle. The hypotenuse is not a straight line, but has a little bend where the slope changes from 0.4 in the blue triangle to 0.375 in the red triangle. The defect is almost imperceptible, which is why the illusion is so striking.

    A numerical coincidence is perhaps the most useful near miss in daily life: 27/12 is almost equal to 3/2. This near miss is the reason pianos have 12 keys in an octave and the basis for the equal-temperament system in Western music. It strikes a compromise between the two most important musical intervals: an octave (a frequency ratio of 2:1) and a fifth (a ratio of 3:2). It is numerically impossible to subdivide an octave in a way that ensures all the fifths will be perfect. But you can get very close by dividing the octave into 12 equal half-steps, seven of which give you a frequency ratio of 1.498. That’s good enough for most people.

    Sometimes near misses arise within the realm of mathematics, almost as if mathematics is playing a trick on itself. In the episode “Treehouse of Horror VI” of The Simpsons, mathematically inclined viewers may have noticed something surprising: the equation 178212 + 184112 = 192212. It seemed for a moment that the screenwriters had disproved Fermat’s Last Theorem, which states that an equation of the form xn + yn = zn has no integer solution when n is larger than 2. If you punch those numbers into a pocket calculator, the equation seems valid. But if you do the calculation with more precision than most hand calculators can manage, you will find that the twelfth root of the left side of the equation is 1921.999999955867 …, not 1922, and Fermat can rest in peace. It is a striking near miss—off by less than a 10-millionth.

    But near misses are more than just jokes. “The ones that are the most compelling to me are the ones where they’re potentially a clue that there’s a big story,” says University of California-Riverside mathematician John Baez. That’s the case for a number sometimes called the Ramanujan constant. This number is eπ √163, which equals approximately 262,537,412,640,768,743.99999999999925—amazingly close to a whole number. A priori, there’s no reason we should expect that these three irrational numbers—e, π, and √163—should somehow combine to form a rational number, let alone a perfect integer. There’s a reason they get so close. “It’s not some coincidence we have no understanding of,” says mathematician John Baez of the University of California, Riverside. “It’s a clue to a deep piece of mathematics.” The precise explanation is complicated, but hinges on the fact that 163 is what is called a Heegner number. Exponentials related to these numbers are nearly integers.

    Or take the mathematical relationship fancifully known as “Monstrous Moonshine.” The story goes that in 1978 mathematician John McKay made an observation both completely trivial and oddly specific: 196,884 = 196,883 + 1. The first number, 196,884, had come up as a coefficient in an important polynomial called the j-invariant, and 196,883 came up in relation to an enormous mathematical object called the Monster group. Many people probably would have shrugged and moved along, but the observations intrigued some mathematicians, who decided to take a closer look. They uncovered connections between two seemingly unrelated subjects: number theory and the symmetries of the Monster group. These linkages may even have broader, as yet ungrasped, significance for other subjects. The physicist Edward Witten has argued that the Monster group may be related to quantum gravity and the deep structure of spacetime.

    Mathematical near misses show the power and playfulness of the human touch in mathematics. Johnson, Kaplan, and others made their discoveries by trial and error—by exploring, like biologists trudging through the rainforest to look for new species. But with mathematics it can be easier to search systematically. For instance, Jim McNeill, a mathematical hobbyist who collects near misses on his website, and Robert Webb, a computer programmer, have developed software for creating and studying polyhedra.

    Near misses live in the murky boundary between idealistic, unyielding mathematics and our indulgent, practical senses. They invert the logic of approximation. Normally the real world is an imperfect shadow of the Platonic realm. The perfection of the underlying mathematics is lost under realizable conditions. But with near misses, the real world is the perfect shadow of an imperfect realm. An approximation is “a not-right estimate of a right answer,” Kaplan says, whereas “a near-miss is an exact representation of an almost-right answer.”

    In this way, near misses transform the mathematician’s and mathematical physicist’s relationship with the natural world. “I am grateful for the imperfections of the real world because it allows me to achieve a kind of quasi-perfection with objects that I know are intrinsically not perfect,” Kaplan says. “It allows me to overcome the limitations of mathematics because of the beautiful brokenness of reality.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

     
  • richardmitnick 9:21 am on May 25, 2017 Permalink | Reply
    Tags: "Unleashing the Power of Synthetic Proteins, , Nautilus, , ,   

    From Nautilus: “Unleashing the Power of Synthetic Proteins” 

    Nautilus

    Nautilus

    March 2017
    David Baker, Baker Lab, U Washngton, BOINC Rosetta@home project



    Dr. David Baker


    Rosetta@home project



    The opportunities for the design of synthetic proteins are endless.

    Proteins are the workhorses of all living creatures, fulfilling the instructions of DNA. They occur in a wide variety of complex structures and carry out all the important functions in our body and in all living organisms—digesting food, building tissue, transporting oxygen through the bloodstream, dividing cells, firing neurons, and powering muscles. Remarkably, this versatility comes from different combinations, or sequences, of just 20 amino acid molecules. How these linear sequences fold up into complex structures is just now beginning to be well understood (see box).

    Even more remarkably, nature seems to have made use of only a tiny fraction of the potential protein structures available—and there are many. Therein lies an amazing set of opportunities to design novel proteins with unique structures: synthetic proteins that do not occur in nature, but are made from the same set of naturally-occurring amino acids. These synthetic proteins can be “manufactured” by harnessing the genetic machinery of living things, such as in bacteria given appropriate DNA that specify the desired amino acid sequence. The ability to create and explore such synthetic proteins with atomic level accuracy—which we have demonstrated—has the potential to unlock new areas of basic research and to create practical applications in a wide range of fields.

    The design process starts by envisioning a novel structure to solve a particular problem or accomplish a specific function, and then works backwards to identify possible amino acid sequences that can fold up to this structure. The Rosetta protein modelling and design software identifies the most likely candidates—those that fold to the lowest energy state for the desired structure. Those sequences then move from the computer to the lab, where the synthetic protein is created and tested—preferably in partnership with other research teams that bring domain expertise for the type of protein being created.

    At present no other advanced technology can beat the remarkable precision with which proteins carry out their unique and beautiful functions. The methods of protein design expand the reach of protein technology, because the possibilities to create new synthetic proteins are essentially unlimited. We illustrate that claim with some of the new proteins we have already developed using this design process, and with examples of the fundamental research challenges and areas of practical application that they exemplify:

    2
    This image shows a designed synthetic protein of a type known as a TIM-barrel. Naturally occurring TIM-barrel proteins are found in a majority of enzymes, the catalysts that facilitate biochemical reactions in our bodies, in part because the circular cup-like or barrel shape at their core provides an appropriate space for the reaction to occur. The synthetic protein shown here has an idealized TIM-barrel template or blueprint that can be customized with pockets and binding sites and catalytic agents specific to particular reactants; the eight helical arms of the protein enhance the reaction space. This process can be used to design whole new classes of enzymes that do not occur in nature. Illustration and protein design prepared by Possu Huang in David Baker’s laboratory, University of Washington.

    Catalysts for clean energy and medicine. Protein enzymes are the most efficient catalysts known, far more so than any synthesized by inorganic chemists. Part of that efficiency comes from their ability to accurately position key parts of the enzyme in relation to reacting molecules, providing an environment that accelerates a reaction or lowers the energy needed for it to occur. Exactly how this occurs remains a fundamental problem which more experience with synthetic proteins may help to resolve.

    Already we have produced synthetic enzymes that catalyze potentially useful new metabolic pathways. These include: reactions that take carbon dioxide from the atmosphere and convert it into organic molecules, such as fuels, more efficiently than any inorganic catalyst, potentially enabling a carbon-neutral source of fuels; and reactions that address unsolved medical problems, including a potential oral therapeutic drug for patients with celiac disease that breaks down gluten in the stomach and other synthetic proteins to neutralize toxic amyloids found in Alzheimer’s disease.

    We have also begun to understand how to design, de novo, scaffolds that are the basis for entire superfamilies of known enzymes (Fig. 1) and other proteins known to bind the smaller molecules involved in basic biochemistry. This has opened the door for potential methods to degrade pollutants or toxins that threaten food safety.

    New super-strong materials. A potentially very useful new class of materials is that formed by hybrids of organic and inorganic matter. One naturally occurring example is abalone shell, which is made up of a combination of calcium carbonate bonded with proteins that results in a uniquely tough material. Apparently, other proteins involved in the process of forming the shell change the way in which the inorganic material precipitates onto the binding protein and also help organize the overall structure of the material. Synthetic proteins could potentially duplicate this process and expand this class of materials. Another class of materials are analogous to spider silk—organic materials that are both very strong and yet biodegradable—for which synthetic proteins might be uniquely suited, although how these are formed is not yet understood. We have also made synthetic proteins that create an interlocking pattern to form a surface only one molecule thick, which suggest possibilities for new anti-corrosion films or novel organic solar cells.

    Targeted therapeutic delivery. Self-assembling protein materials make a wide variety of containers or external barriers for living things, from protein shells for viruses to the exterior wall of virtually all living cells. We have developed a way to design and build similar containers: very small cage-like structures—protein nanoparticles—that self-assemble from one or two synthetic protein building blocks (Fig. 2). We do this extremely precisely, with control at the atomic level. Current work focuses on building these protein nanoparticles to carry a desired cargo—a drug or other therapeutic—inside the cage, while also incorporating other proteins of interest on their surface. The surface protein is chosen to bind to a similar protein on target cells.

    These self-assembling particles are a completely new way of delivering drugs to cells in a targeted fashion, avoiding harmful effects elsewhere in the body. Other nanoparticles might be designed to penetrate the blood-brain barrier, in order to deliver drugs or other therapies for brain diseases. We have also generated methods to design proteins that disrupt protein-protein interactions and proteins that bind to small molecules for use in biosensing applications, such as identifying pathogens. More fundamentally, synthetic proteins may well provide the tools that enable improved targeting of drugs and other therapies, as well as an improved ability to bond therapeutic packages tightly to a target cell wall.

    5
    A tiny 20-sided protein nanoparticle that can deliver drugs or other therapies to specific cells in the body with minimal side effects. The nanoparticle self-assembles from two types of synthetic proteins. Illustration and protein design prepared by Jacob Bale in David Baker’s laboratory, University of Washington.

    Novel vaccines for viral diseases. In addition to drug delivery, self-assembling protein nanoparticles are a promising foundation for the design of vaccines. By displaying stabilized versions of viral proteins on the surfaces of designed nanoparticles, we hope to elicit strong and specific immune responses in cells to neutralize viruses like HIV and influenza. We are currently investigating the potential of these nanoparticles as vaccines against a number of viruses. The thermal stability of these designer vaccines should help eliminate the need for complicated cold chain storage systems, broadening global access to life saving vaccines and supporting goals for eradication of viral diseases. The ability to shape these designed vaccines with atomic level accuracy also enables a systematic study of how immune systems recognize and defend against pathogens. In turn, the findings will support development of tolerizing vaccines, which could train the immune system to stop attacking host tissues in autoimmune disease or over-reacting to allergens in asthma.

    New peptide medicines. Most approved drugs are either bulky proteins or small molecules. Naturally occurring peptides (amino acid compounds) that are constrained or stabilized so that they precisely complement their biological target are intermediate in size, and are among the most potent pharmacological compounds known. In effect, they have the advantages of both proteins and small molecule drugs. The antibiotic cyclosporine is a familiar example. Unfortunately such peptides are few in number.

    We have recently demonstrated a new computational design method that can generate two broad classes of peptides that have exceptional stability against heat or chemical degradation. These include peptides that can be genetically encoded (and can be produced by bacteria) as well as some that include amino acids that do not occur in nature. Such peptides are, in effect, scaffolds or design templates for creating whole new classes of peptide medicines.

    In addition, we have developed general methods for designing small and stable proteins that bind strongly to pathogenic proteins. One such designed protein binds the viral glycoprotein hemagglutinin, which is responsible for influenza entry into cells. These designed proteins protect infected mice in both a prophylactic and therapeutic manner and therefore are potentially very powerful anti-flu medicines. Similar methods are being applied to design therapeutic proteins against the Ebola virus and other targets that are relevant in cancer or autoimmune diseases. More fundamentally, synthetic proteins may be useful as test probes in working out the detailed molecular chemistry of the immune system.

    Protein logic systems. The brain is a very energy-efficient logic system based entirely on proteins. Might it be possible to build a logic system—a computer—from synthetic proteins that would self-assemble and be both cheaper and more efficient than silicon logic systems? Naturally occurring protein switches are well studied, but building synthetic switches remains an unsolved challenge. Quite apart from bio-technology applications, understanding protein logic systems may have more fundamental results, such as clarifying how our brains make decisions or initiate processes.

    The opportunities for the design of synthetic proteins are endless, with new research frontiers and a huge variety of practical applications to be explored. In effect, we have an emerging ability to design new molecules to solve specific problems—just as modern technology does outside the realm of biology. This could not be a more exciting time for protein design.

    Predicting Protein Structure

    If we were unable to predict the structure that results from a given sequence of amino acids, synthetic protein design would be an almost impossible task. There are 20 naturally-occurring amino acids, which can be linked in any order and can fold into an astronomical number of potential structures. Fortunately the structure prediction problem is now well on the way toward being solved by the Rosetta protein modeling software.

    The Rosetta tool evaluates possible structures, calculates their energy states, and identifies the lowest energy structure—usually, the one that occurs in a living organism. For smaller proteins, Rosetta predictions are already reasonably accurate. The power and accuracy of the Rosetta algorithms are steadily improving thanks to the work of a cooperative global network of several hundred protein scientists. New discoveries—such as identifying amino acid pairs that co-evolve in living systems and thus are likely to be co-located in protein structures—are also helping to improve prediction accuracy.

    Our research team has already revealed the structures for more than a thousand protein families, and we expect to be able to predict the structure for nearly any protein within a few years. This is an important achievement with direct significance for basic biology and biomedical science, since understanding structure leads to understanding the function of the myriad proteins found in the human body and in all living things. Moreover, predicting protein structure is also the critical enabling tool for designing novel, “synthetic” proteins that do not occur in nature.

    How to Create Synthetic Proteins that Solve Important Problems

    6
    A graduate student in the Baker lab and a researcher at the Institute for Protein Design discuss a bacterial culture (in the Petri dish) that is producing synthetic proteins. Source: Laboratory of David Baker, University of Washington.

    Now that it is possible to design a variety of new proteins from scratch, it is imperative to identify the most pressing problems that need to be solved, and focus on designing the types of proteins that are needed to address these problems. Protein design researchers need to collaborate with experts in a wide variety of fields to take our work from initial protein design to the next stages of development. As the examples above suggest, those partners should include experts in industrial scale catalysis, fundamental materials science and materials processing, biomedical therapeutics and diagnostics, immunology and vaccine design, and both neural systems and computer logic. The partnerships should be sustained over multiple years in order to prioritize the most important problems and test successive potential solutions.

    A funding level of $100M over five years would propel protein design to the forefront of biomedical research, supporting multiple and parallel collaborations with experts worldwide to arrive at breakthroughs in medicine, energy, and technology, while also furthering a basic understanding of biological processes. Current funding is unable to meet the demands of this rapidly growing field and does not allow for the design and production of new proteins at an appropriate scale for testing and ultimately production, distribution, and implementation. Private philanthropy could overcome this deficit and allow us to jump ahead to the next generation of proteins—and thus to use the full capacity of the amino acid legacy that evolution has provided us.

    My BOINC

    See the full article here .

    Please help promote STEM in your local schools.

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    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

     
  • richardmitnick 8:58 am on May 25, 2017 Permalink | Reply
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    From Nautilus: “Opening a New Window into the Universe” 

    Nautilus

    Nautilus

    April 2017
    Andrea Ghez, UCLA, UCO

    7
    Andrea Ghez. PBS NOVA

    The UCO Lick C. Donald Shane telescope is a 120-inch (3.0-meter) reflecting telescope located at the Lick Observatory, Mt Hamilton, in San Jose, California

    Keck Observatory, Mauna Kea, Hawaii, USA

    New technology could bring new insights into the nature of black holes, dark matter, and extrasolar planets.

    Earthbound telescopes see stars and other astronomical objects through a haze. The light waves they gather have traveled unimpeded through space for billions of years, only to be distorted in the last millisecond by the Earth’s turbulent atmosphere. That distortion is now even more important, because scientists are preparing to build the three largest telescopes on Earth, each with light-gathering surfaces of 20 to 40 meters across.

    The new giant telescopes:

    ESO/E-ELT,to be on top of Cerro Armazones in the Atacama Desert of northern Chile


    TMT-Thirty Meter Telescope, proposed for Mauna Kea, Hawaii, USA


    Giant Magellan Telescope, to be at Las Campanas Observatory, to be built some 115 km (71 mi) north-northeast of La Serena, Chile

    In principle, the larger the telescope, the higher the resolution of astronomical images. In practice, the distorting veil of the atmosphere has always limited what can be achieved. Now, a rapidly evolving technology known as adaptive optics can strip away the veil and enable astronomers to take full advantage of current and future large telescopes. Indeed, adaptive optics is already making possible important discoveries and observations, including: the discovery of the supermassive black hole at the center of our galaxy, proving that such exotic objects exist; the first images and spectra of planetary systems around other stars; and high-resolution observations of galaxies forming in the early universe.

    But adaptive optics has still not delivered its full scientific potential.

    ESO 4LGSF Adaptive Optics Facility (AOF)

    Existing technology can only partially correct the atmospheric blurring and cannot provide any correction for large portions of the sky or for the majority of the objects astronomers want to study.

    The project we propose here to fully exploit the potential of adaptive optics by taking the technology to the next level would boost research on a number of critical astrophysical questions, including:

    What are supermassive black holes and how do they work? Adaptive Optics has opened a new approach to studying supermassive black holes—through stellar orbits—but only the brightest stars, the tip of the iceberg, have been measured. With next generation adaptive optics we will be able to take the next leap forward in our studies of these poorly understood objects that are believed to play a central role in our universe. The space near the massive black hole at the center of our galaxy, for example, is a place where gravitational forces reach extreme levels. Does Einstein’s general theory of relativity still apply, or do exotic new physical phenomena emerge? How do these massive black holes shape their host galaxies? Early adaptive optics observations at the galactic center have revealed a completely unexpected environment, challenging our notions on the relationship between black holes and galaxies, which are a fundamental ingredient to cosmological models. One way to answer both of these questions is to find and measure the orbits of faint stars that are closer to the black hole than any known so far—which advanced adaptive optics would make possible.
    The first direct images of an extrasolar planet—obtained with adaptive optics—has raised fundamental questions about star and planet formation. How exactly do new stars form and then spawn planets from the gaseous disks around them? New, higher resolution images of this process—with undistorted data from larger telescopes—can help answer this question, and may also reveal how our solar system was formed. In addition, although only a handful of new-born planets has been found to date, advanced adaptive optics will enable astronomers to find many more and help determine their composition and life-bearing potential.
    Dark matter and dark energy are still completely mysterious, even though they constitute most of the universe.


    Dark Energy Camera [DECam], built at FNAL


    NOAO/CTIO Victor M Blanco 4m Telescope which houses the DECam at Cerro Tololo, Chile, housing DECam

    But detailed observations using adaptive optics of how light from distant galaxies is refracted around a closer galaxy to form multiple images—so-called gravitational lensing—can help scientists understand how dark matter and dark energy change space itself.

    In addition, it is clear that telescopes endowed with advanced adaptive optics technology will inspire a whole generation of astronomers to design and carry out a multitude of innovative research projects that were previously not possible.

    4
    The laser system used to make artificial guide stars that sense the blurring effects of the Earth’s atmosphere being used on both Keck I and Keck II during adaptive optics observations of the center of our Galaxy. Next Generation Adaptive Optics would have multiple laser beams for each telescope. Ethan Tweedie

    Sag A* NASA Chandra X-Ray Observatory 23 July 2014, the supermassive black hole at the center of the Milky Way

    The technology of adaptive optics is quite simple, in principle. First, astronomers measure the instantaneous turbulence in the atmosphere by looking at the light from a bright, known object—a “guide star”—or by using a laser tuned to make sodium atoms in a thin layer of the upper atmosphere fluoresce and glow as an artificial guide star.

    6
    ESO VLT Adaptive Optics new Guide Star laser light

    The turbulence measurements are used to compute (also instantaneously) the distortions that turbulence creates in the incoming light waves. Those distortions are then counteracted by rapidly morphing the surface of a deformable mirror in the telescope. Measurements and corrections are done hundreds of times per second—which is only possible with powerful computing capability, sophisticated opto-mechanical linkages, and a real-time control system. We know how to build these tools.

    Of course, telescopes that operate above the atmosphere, such as the Hubble Space Telescope, don’t need adaptive optics.

    NASA/ESA Hubble Telescope

    But both the Hubble and the coming next generation of space telescopes are small compared to the enormous earth-based telescopes now being planned.


    LSST Camera, built at SLAC



    LSST telescope, currently under construction at Cerro Pachón Chile, a 2,682-meter-high mountain in Coquimbo Region, in northern Chile, alongside the existing Gemini South and Southern Astrophysical Research Telescopes.

    And for the kinds of research that require very high resolution, such as the topics mentioned above and many others, there is really no substitute for the light-gathering power of telescopes too huge to be put into space.

    The next generation of adaptive optics could effectively take even the largest earth-bound telescopes “above the atmosphere” and make them truly amazing new windows on the universe. We know how to create this capability—the technology is in hand and the teams are assembled. It is time to put advanced adaptive optics to work.

    Creating Next Generation Adaptive Optics

    Adaptive optics (AO) imaging technology is used to improve the performance of optical systems by correcting distortions on light waves that have traveled through a turbulent medium. The technology has revolutionized fields from ophthalmology and vision science to laser communications. In astronomy, AO uses sophisticated, deformable mirrors controlled by fast computers to correct, in real-time, the distortion caused by the turbulence of the Earth’s atmosphere. Telescopes equipped with AO are already producing sharper, clearer views of distant astronomical objects than had ever before been possible, even from space. But current AO systems only partially correct for the effects of atmospheric blurring, and only when telescopes are pointed in certain directions. The aim of Next Generation Adaptive Optics is to overcome these limitations and provide precise correction for atmospheric blurring anywhere in the sky.

    One current limitation is the laser guide star that energizes sodium atoms in the upper atmosphere and causes them to glow as an artificial star used to measure the atmospheric distortions. This guide “star” is relatively close, only about 90 kilometers above the Earth’s surface, so the technique only probes a conical volume of the atmosphere above the telescope, and not the full cylinder of air through which genuine star light must pass to reach the telescope. Consequently, much of the distorting atmospheric structure is not measured. The next generation AO we propose will employ seven laser guide stars, providing full coverage of the entire cylindrical path travelled by light from the astronomical object being studied.

    6
    The next generation of adaptive optics will have several laser-created artificial guide stars, better optics, higher performance computers, and more advanced science instruments. Such a system will deliver the highest-definition images and spectra over nearly the entire sky and will enable unique new means of measuring the properties of stars, planets, galaxies, and black holes.
    J.Lu (U of Hawaii) & T. Do (UCLA)

    This technique can map the 3-D structure of the atmosphere, similar to how MRI medical imaging maps the human body. Simulations demonstrate that the resulting corrections will be excellent and stable, yielding revolutionary improvements in imaging. For example, the light from a star will be concentrated into a tiny area of the focal plane camera, and be far less spread out than it is with current systems, giving sharp, crisp images that show the finest detail possible.

    This will be particularly important for existing large telescopes such as the W. M. Keck Observatory (WMKO) [above]—currently the world’s leading AO platform in astronomy. Both our team—the UCLA Galactic Center Group (GCG)—and the WMKO staff have been deeply involved in the development of next generation AO systems.

    The quantum leap in the quality of both imaging and spectroscopy that next generation AO can bring to the Keck telescopes will likely pave the way for advanced AO systems on telescopes around the globe. For the next generation of extremely large telescopes, however, these AO advances will be critical. This is because the cylindrical volume of atmosphere through which light must pass to reach the mirrors in such large telescopes is so broad that present AO techniques will not be able to provide satisfactory corrections. For that reason, next generation AO techniques are critical to the future of infrared astronomy, and eventually of optical astronomy as well.

    The total proposed budget is $80 million over five years. The three major components necessary to take the leap in science capability include the laser guide star system, the adaptive optics system, and a powerful new science instrument, consisting of an infrared imager and an infrared spectrograph, that provides the observing capability to take advantage of the new adaptive optics system. This investment in adaptive optics will also help develop a strong workforce for other critical science and technology industries, as many students are actively recruited into industry positions in laser communications, bio-medical optics, big-data analytics for finance and business, image sensing and optics for government and defense applications, and the space industry. This investment will also help keep the U.S. in the scientific and technological lead. Well-funded European groups have recognized the power of AO and are developing competitive systems, though the next generation AO project described here will set an altogether new standard.

    Federal funding agencies find the science case for this work compelling, but they have made clear that it is beyond present budgetary means. Therefore, this is an extraordinary opportunity for private philanthropy—for visionaries outside the government to help bring this ambitious breakthrough project to reality and open a new window into the universe.

    Andrea Ghez is the Lauren B. Leichtman & Arthur E. Levine Chair in Astrophysics Director, UCLA Galactic Center Group.

    See the full article here .

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    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

     
  • richardmitnick 8:25 am on May 25, 2017 Permalink | Reply
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    From Nautilus: “The Origin of the Universe” 

    Nautilus

    Nautilus

    April 2017
    John Carlstrom

    1
    The current South Pole telescope measuring small variations in the cosmic microwave background radiation that permeates the universe. Multiple telescopes with upgraded detectors could unlock additional secrets about the origins of the universe. Jason Gallicchio

    Measuring tiny variations in the cosmic microwave background will enable major discoveries about the origin of the universe.

    CMB per ESA/Planck


    ESA/Planck

    How is it possible to know in detail about things that happened nearly 14 billion years ago? The answer, remarkably, could come from new measurements of the cosmic microwave radiation that today permeates all space, but which was emitted shortly after the universe was formed.

    Previous measurements of the microwave background showed that the early universe was remarkably uniform, but not perfectly so: There are small variations in the intensity (or temperature) and polarization of the background radiation. These faint patterns show close agreement with predictions from what is now the standard theoretical model of how the universe began. That model describes an extremely energetic event—the Big Bang—followed within a tiny fraction of a second by a period of very accelerated expansion of the universe called cosmic inflation.

    4
    Alan Guth, Highland Park High School, NJ, USA and M.I.T., who first proposed cosmic inflation

    HPHS Owls

    Lambda-Cold Dark Matter, Accelerated Expansion of the Universe, Big Bang-Inflation (timeline of the universe) Date 2010 Credit: Alex MittelmannColdcreation

    5
    Alan Guth’s notes. http://www.bestchinanews.com/Explore/4730.html

    During this expansion, small quantum fluctuations were stretched to astrophysical scales, becoming the seeds that gave rise to the galaxies and other large-scale structures of the universe visible today.

    Universe map Sloan Digital Sky Survey (SDSS) 2dF Galaxy Redshift Survey

    After the cosmic inflation ended, the expansion began to slow and the primordial plasma of radiation and high-energy sub-atomic particles began to cool. Within a few hundred thousand years, the plasma had cooled sufficiently for atoms to form, for the universe to become transparent to light, and for the first light to be released. That first light has since been shifted—its wavelengths stretched 1,000-fold into the microwave spectrum by the continuing expansion of the universe—and is what we now measure as the microwave background [see above].

    Inflationary Universe. NASA/WMAP

    Recently the development of new superconducting detectors and more powerful telescopes are providing the tools to conduct an even more detailed study of the microwave background. And the payoff could be immense, including additional confirmation that cosmic inflation actually occurred, when it occurred, and how energetic it was, in addition to providing new insights into the quantum nature of gravity. Specifically the new research we propose can address a wide range of fundamental questions:

    1. The accelerated expansion of the universe in the first fraction of a second of its existence, as described by the inflation model, would have created a sea of gravitational waves. These distortions in spacetime would in turn would have left a distinct pattern in the polarization of the microwave background. Detecting that pattern would thus provide a key test of the inflation model, because the level of the polarization links directly to the time of inflation and its energy scale.
    2. Investigating the cosmic gravitational wave background would build on the stunning recent discovery of gravity waves, apparently from colliding black holes, helping to further the new field of gravitational wave astronomy.
    3. These investigations would provide a valuable window on physics at unimaginably high energy scales, a trillion times more energetic than the reach of the most powerful Earth-based accelerators.
    4. The cosmic microwave background provides a backlight on all structure in the universe. Its precise measurement will illuminate the evolution of the universe to the present day, allowing unprecedented insights and constraints on its still mysterious contents and the laws that govern them.

    The origin of the universe was a fantastic event. To gain an understanding of that beginning as an inconceivably small speck of spacetime and its subsequent evolution is central to unraveling continuing mysteries such as dark matter and dark energy. It can shed light on how the two great theories of general relativity and quantum mechanics relate to each other. And it can help us gain a clearer perspective on our human place within the universe. That is the opportunity that a new generation of telescopes and detectors can unlock.

    How to Measure Variations in the Microwave Background with Unparalleled Precision

    2
    Figure 1Ultra-sensitive superconducting bolometer detectors manufactured with thin-film techniques. The project proposes to deploy 500,000 such detectors. Chrystian Posada Arbelaez.

    The time for the next generation cosmic microwave background experiment is now. Transformational improvements have been made in both the sensitivity of microwave detectors and the ability to manufacture them in large numbers at low cost. The advance stems from the development of ultra-sensitive superconducting detectors called bolometers. These devices (Figure 1) essentially eliminate thermal noise by operating at a temperature close to absolute zero, but also are designed to make sophisticated use of electrothermal feedback—adjusting the current to the detectors when incoming radiation deposits energy, so as to keep the detector at its critical superconducting transition temperature under all operating conditions. The sensitivity of these detectors is limited only by the noise of the incoming signal—they generate an insignificant amount of noise of their own.

    Equally important are the production advances. These new ultra-sensitive detectors are manufactured with thin film techniques adapted from Silicon Valley—although using exotic superconducting materials—so that they can be rapidly and uniformly produced at greatly reduced cost. That’s important, because the proposed project needs to deploy about 500,000 detectors in all—something that would not be possible with hand-assembled devices as in the past. Moreover, the manufacturing techniques allow these sophisticated detectors to automatically filter the incoming signals for the desired wavelength sensitivity.

    3
    Figure 2The current focal plane on the South Pole Telescope with seven wafers of detectors plus hand-assembled individual detectors. A single detector wafer of the advanced design proposed here would provide more sensitivity and frequency coverage than this entire focal plane; the project would deploy several hundred such wafers across 10 or more telescopes. Jason Henning.

    To deploy the detectors, new telescopes are needed that have a wide enough focal plane to accommodate a large number of detectors—about 10,000 per telescope to capture enough incoming photons and see a wide enough area of the sky (Figure 2). They need to be placed at high altitude, exceedingly dry locations, so as to minimize the water vapor in the atmosphere that interferes with the incoming photons. The plan is to build on the two sites already established for ongoing background observations, the high Antarctic plateau at the geographic South Pole, and the high Atacama plateau in Chile. Discussions are underway with the Chinese about developing a site in Tibet; Greenland is also under consideration. In all, about 10 specialized telescopes will be needed, and will need to operate for roughly 5 years to accomplish the scientific goals described above. Equally important, the science teams that have come together to do this project will need significant upgrades to their fabrication and testing capabilities.

    The resources needed to accomplish this project are estimated at $100 million over 10 years, in addition to continuation of current federal funding. The technology is already proven and the upgrade path understood. Equally important, a cadre of young, enthusiastic, and well-trained scientists are eager to move forward. Unfortunately, constraints on the federal funding situation are already putting enormous stress on the ability of existing teams just to continue, and the expanded resources to accomplish the objectives described above are not available. This is thus an extraordinary opportunity for private philanthropy—an opportunity to “see” back in time to the very beginning of the universe and to understand the phenomena that shaped our world.

    See the full article here .

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    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

     
  • richardmitnick 9:41 pm on May 18, 2017 Permalink | Reply
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    From Nautilus: “The Physicist Who Denies Dark Matter” Revised and Improved from post of 2017/03/01 

    Nautilus

    Nautilus

    May 18, 2017
    Oded Carmeli

    4
    Mordehai Milgrom. Cosmos on Nautilus

    Maybe Newtonian physics doesn’t need dark matter to work.

    He is one of those dark matter people,” Mordehai Milgrom said about a colleague stopping by his office at the Weizmann Institute of Science. Milgrom introduced us, telling me that his friend is searching for evidence of dark matter in a project taking place just down the hall.

    “There are no ‘dark matter people’ and ‘MOND people,’ ” his colleague retorted.

    7
    http://www.astro.umd.edu/~ssm/mond/

    “I am ‘MOND people,’” Milgrom proudly proclaimed, referring to Modified Newtonian Dynamics, his theory that fixes Newtonian physics instead of postulating the existence of dark matter and dark energy—two things that, according to the standard model of cosmology, constitute 95.1 percent of the total mass-energy content of the universe.

    This friendly incident is indicative of (“Moti”) Milgrom’s calmly quixotic character. There is something almost misleading about the 70-year-old physicist wearing shorts in the hot Israeli summer, whose soft voice breaks whenever he gets excited. Nothing about his pleasant demeanor reveals that this man claims to be the third person to correct Newtonian physics: First Max Planck (with quantum theory), then Einstein (with relativity), now Milgrom.

    This year marks Milgrom’s 50th year at the Weizmann.


    Weizmann Institute Campus

    I visited him there to learn more about how it feels to be a science maverick, what he appreciates about Thomas Kuhn’s The Structure of Scientific Revolutions, and why he thinks dark matter and dark energy don’t exist.

    1
    NASA

    What inspired you to dedicate your life to the motion of stars?

    I remember very vividly the way physics struck me. I was 16 and I thought: Here is a way to understand how things work, far beyond the understanding of my peers. It wasn’t a long-term plan. It was a daily attraction. I simply loved physics, the same way other people love art or sports. I never dreamed of one day making a major discovery, like correcting Newton.

    I had a terrific physics teacher at school, but when you study textbook material, you’re studying done deals. You still don’t see the effort that goes into making breakthrough science, when things are unclear and advances are made intuitively and often go wrong. They don’t teach you that at school. They teach you that science always goes forward: You have a body of knowledge, and then someone discovers something and expands that body of knowledge. But it doesn’t really work that way. The progress of science is never linear.

    How did you get involved with the problem of dark matter?

    Toward the end of my Ph.D., the physics department here wanted to expand. So they asked three top Ph.D. students working on particle physics to choose a new field. We chose astrophysics, and the Weizmann Institute pulled some strings with institutions abroad so they would accept us as postdocs. And so I went to Cornell to fill my gaps in astrophysics.

    After a few years in high energy astrophysics, working on the physics of X-ray radiation in space, I decided to move to yet another field: The dynamics of galaxies. It was a few years after the first detailed measurements of the speed of stars orbiting spiral galaxies came in. And, well, there was a problem with the measurements.

    To understand this problem, one needs to wrap one’s head around some celestial rotations. Our planet orbits the sun, which, in turn, orbits the center of the Milky Way galaxy. Inside solar systems, the gravitational pull from the mass of the sun and the speed of the planets are in balance. By Newton’s laws, this is why Mercury, the innermost planet in our solar system, orbits the sun at over 100,000 miles per hour, while the outermost plant, Neptune, is crawling at just over 10,000 miles per hour.

    Milky Way NASA/JPL-Caltech /ESO R. Hurt

    Now, you might assume that the same logic would apply to galaxies: The farther away the star is from the galaxy’s center, the slower it revolves around it; however, while at smaller radiuses the measurements were as predicted by Newtonian physics, farther stars proved to move much faster than predicted from the gravitational pull of the mass we see in these galaxies. The observed gap got a lot wider when, in the late 1970s, radio telescopes were able to detect and measure the cold gas clouds at the outskirts of galaxies. These clouds orbit the galactic center five times farther than the stars, and thus the anomaly grew to become a major scientific puzzle.

    One way to solve this puzzle is to simply add more matter. If there is too little visible mass at the center of galaxies to account for the speed of stars and gas, perhaps there is more matter than meets the eye, matter that we cannot see, dark matter.

    What made you first question the very existence of dark matter?

    What struck me was some regularity in the anomaly. The rotational velocities were not just larger than expected, they became constant with radius. Why? Sure, if there was dark matter, the speed of stars would be greater, but the rotation curves, meaning the rotational speed drawn as a function of the radius, could still go up and down depending on its distribution. But they didn’t. That really struck me as odd. So, in 1980, I went on my Sabbatical in the Institute for Advance Studies in Princeton with the following hunch: If the rotational speeds are constant, then perhaps we’re looking at a new law of nature. If Newtonian physics can’t predict the fixed curves, perhaps we should fix Newton, instead of making up a whole new class of matter just to fit our measurements.

    If you’re going to change the laws of nature that work so well in our own solar system, you need to find a property that differentiates solar systems from galaxies. So I made up a chart of different properties, such as size, mass, speed of rotation, etc. For each parameter, I put in the Earth, the solar system and some galaxies. For example, galaxies are bigger than solar systems, so perhaps Newton’s laws don’t work over large distances? But if this was the case, you would expect the rotation anomaly to grow bigger in bigger galaxies, while, in fact, it is not. So I crossed that one out and moved on to the next properties.

    I finally struck gold with acceleration: The pace at which the velocity of objects changes.

    3
    NASA

    We usually think of earthbound cars that accelerate in the same direction, but imagine a merry-go-round. You could be going in circles and still accelerate. Otherwise, you would simply fall off. The same goes for celestial merry-go-rounds. And it’s in acceleration that we find a big difference in scales, one that justifies modifying Newton: The normal acceleration for a star orbiting the center of a galaxy is about a hundred million times smaller than that of the Earth orbiting the sun.

    For those small accelerations, MOND introduces a new constant of nature, called a0. If you studied physics in high school, you probably remember Newton’s second law: force equals mass times acceleration, or F=ma. While this is a perfectly good tool when dealing with accelerations much greater than a0, such as those of the planets around our sun, I suggested that at significantly lower accelerations, lower even than that of our sun around the galactic center, force becomes proportional to the square of the acceleration, or F=ma2/a0.

    To put it in other words: According to Newton’s laws, the rotation speed of stars around galactic centers should decrease the farther the star is from the center of mass. If MOND is correct, it should reach a constant value, thus eliminating the need for dark matter.

    What did your colleagues at Princeton think about all this?

    I didn’t share these thoughts with my colleagues at Princeton. I was afraid to come across as, well, crazy. And then, in 1981, when I already had a clear idea of MOND, I didn’t want anyone to jump on my wagon, so to speak, which is even crazier when you think about it. Needless to say [laughs] no one jumped on my wagon, even when I desperately wanted them to.

    Well, you were 35 and you proposed to fix Newton.

    Why not? What’s the big deal? If something doesn’t work, fix it. I wasn’t trying to be bold. I was very naïve at the time. I didn’t understand that scientists are just as swayed as other people by conventions and interests.

    Like Thomas Kuhn’s The Structure of Scientific Revolutions.

    10

    I love that book. I read it several times. It showed me how my life’s story has happened to so many others scientists throughout history. Sure, it’s easy to make fun of people who once objected to what we now know is good science, but are we any different? Kuhn stresses that these objectors are usually good scientists with good reasons to object. It is just that the dissenters usually have a unique point of view of things that is not shared by most others. I laugh about it now, because MOND has made such progress, but there were times when I felt depressed and isolated.

    What’s it like being a science maverick?

    By and large, the last 35 years have been exciting and rewarding exactly because I have been advocating a maverick paradigm. I am a loner by nature, and despite the daunting and doubting times, I much prefer this to being carried with the general flow. I was quite confident in the basic validity of MOND from the very start, which helped me a lot in taking all this in stride, but there are two great advantages to the lingering opposition to MOND: Firstly, it gave me time to make more contributions to MOND than I would had the community jumped on the MOND wagon early on. Secondly, once MOND is accepted, the long and wide resistance to it will only have proven how nontrivial an idea it is.

    By the end of my sabbatical in Princeton, I had secretly written three papers introducing MOND to the world. Publishing them, however, was a whole different story. At first I sent my kernel paper to journals such as Nature and Astrophysical Journal Letters, and it got rejected almost off-hand. It took a long time until all three papers were published, side by side, in Astrophysical Journal.

    The first person to hear about MOND was my wife Yvonne. Frankly, tears come to my eyes when I say this. Yvonne is not a scientist, but she has been my greatest supporter.

    The first scientist to back MOND was another physics maverick: The late Professor Jacob Bekenstein, who was the first to suggest that black holes should have a well-defined entropy, later dubbed the Bekenstein-Hawking entropy. After I submitted the initial MOND trilogy, I sent the preprints to several astrophysicists, but Jacob was the first scientist I discussed MOND with. He was enthusiastic and encouraging from the very start.

    Slowly but surely, this tiny opposition to dark matter grew from just two physicists to several hundred proponents, or at least scientists who take MOND seriously. Dark matter is still the scientific consensus, but MOND is now a formidable opponent that proclaims the emperor has no clothes, that dark matter is our generation’s ether.

    So what happened? As far as dark matter is concerned, nothing really. A host of experiments searching for dark matter, including the Large Hadron Collider, many underground experiments and several space missions, have failed to directly observe its very existence. Meanwhile, MOND was able to accurately predict the rotation of more and more spiral galaxies—over 150 galaxies to date, to be precise.

    All of them? Some papers claim that MOND wasn’t able to predict the dynamics of certain galaxies.

    That’s true and it’s perfectly fine, because MOND’s predictions are based on measurements. Given the distribution of regular, visible matter alone, MOND can predict the dynamics of galaxies. But that prediction is based on our initial measurements. We measure the light coming in from a galaxy to calculate its mass, but we often don’t know the distance to that galaxy for sure, so we don’t know for certain just how massive that galaxy really is. And there are other variables, such as molecular gas, that we can’t observe at all. So yes, some galaxies don’t perfectly match MOND’s predictions, but all in all, it’s almost a miracle that we have enough data on galaxies to prove MOND right, over and over again.

    Your opponents say MOND’s greatest flaw is its incompatibility with relativistic physics.

    In 2004, Bekenstein proposed his TeVeS, or Relativistic Gravitational Theory for MOND.

    12
    http://astroweb.case.edu/ssm/mond/

    Since then, several different relativistic MOND formulations have been put forth, including one by me, called Bimetric MOND, or BIMOND.

    So, no, incorporating MOND into Einsteinian physics is no longer a challenge. I hear this statement still made, but only from people who parrot others, who themselves are not abreast with the developments of the last 10 years. There are several relativistic versions of MOND. What remains a challenge is demonstrating that MOND can account for the mass anomalies in cosmology.

    Another argument that cosmologists often make is that dark matter is needed not just for motion within galaxies, but on even larger scales. What does MOND have to say about that?

    According to the Big Bang theory, the universe began as a uniform singularity 13.8 billion years ago. And, just as in galaxies, observations made of the cosmic background radiation from the early universe suggest that the gravity of all the matter in the universe is simply not enough to form the different patterns we currently see, like galaxies and stars, in just 13.8 billion years. Once again, dark matter was called to the rescue: It does not emit radiation, but it does engage visible material with gravitation. And so, starting from the 1980s, the new cosmological dogma was that dark matter constituted a staggering 95 percent of all matter in the universe. That lasted, well, right until the bomb hit us in 1998.

    It turned out that the expansion of the universe is accelerating, not decelerating like all of us originally thought.

    13
    Timeline of the universe, assuming a cosmological constant. Coldcreation/wikimedia, CC BY-SA

    Any form of genuine matter, dark or not, should have slowed down acceleration. And so a whole new type of entity was invented: Dark energy. Now the accepted cosmology is that the universe is made up of 70 percent dark energy, 25 percent dark matter, and 5 percent regular matter..

    Dark energy depiction. Image: Volker Springle/Max Planck Institute for Astrophysics/SP)

    But dark energy is just a quick fix, the same as dark matter is. And just as in galaxies, you can either invent a whole new type of energy and then spend years trying to understand its properties, or you can try fixing your theory.

    Among other things, MOND points to a very deep connection between structure and dynamics in galaxies and cosmology. This is not expected in accepted physics. Galaxies are tiny structures within the grand scale of the universe, and those structures can behave differently without contradicting the current cosmological consensus. However, MOND creates this connection, binding the two.

    This connection is surprising: For whatever reason, the MOND constant of a0 is close to the acceleration that characterizes the universe itself. In fact, MOND’s constant equals the speed of light squared, divided by the radius of universe.

    So, indeed, to your question, the conundrum pointed to is valid at present. MOND doesn’t have a sufficient cosmology yet, but we’re working on it. And once we fully understand MOND, I believe we’ll also fully understand the expansion of the universe, and vice versa: A new cosmological theory would explain MOND. Wouldn’t that be amazing?

    What do you think about the proposed unified theories of physics, which merge MOND with quantum mechanics?

    These all hark back to my 1999 paper on MOND as a vacuum effect, where it was pointed out that the quantum vacuum in a universe such as ours may produce MOND behavior within galaxies, with the cosmological constant appearing in the guise of the MOND acceleration constant, a0. But I am greatly gratified to see these propositions put forth, especially because they are made by people outside the traditional MOND community. It is very important that researchers from other backgrounds become interested in MOND and bring new ideas to further our understanding of its origin.

    And what if you had a unified theory of physics that explains everything? What then?

    You know, I’m not a religious person, but I often think about our tiny blue dot, and the painstaking work we physicists do here. Who knows? Perhaps somewhere out there, in one of those galaxies I spent my life researching, there already is a known unified theory of physics, with a variation of MOND built into it. But then I think: So what? We still had fun doing the math. We still had the thrill of trying to wrap our heads around the universe, even if the universe never noticed it at all.

    See the full article here .

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    Welcome to Nautilus. We are delighted you joined us. We are here to tell you about science and its endless connections to our lives. Each month we choose a single topic. And each Thursday we publish a new chapter on that topic online. Each issue combines the sciences, culture and philosophy into a single story told by the world’s leading thinkers and writers. We follow the story wherever it leads us. Read our essays, investigative reports, and blogs. Fiction, too. Take in our games, videos, and graphic stories. Stop in for a minute, or an hour. Nautilus lets science spill over its usual borders. We are science, connected.

     
  • richardmitnick 1:32 pm on May 11, 2017 Permalink | Reply
    Tags: Defy the Stars, Nautilus, SciFi   

    From Nautilus: “Defy the Stars” spoiler alert, this is SciFi. 

    Nautilus

    Nautilus

    May 11, 2017
    Claudia Gray

    Count to five, Noemi decides. If she’s cracking up—if the terror of the past few minutes has scrambled her mind to the point where she’s hallucinating—then this will all go away in a couple of seconds. If this is for real, the mech will be standing here waiting for orders when she’s done.

    One. The mech remains still, expression curious and patient.

    Two. Noemi takes a deep breath. She remains in her crouch, hand clutching her blaster so tightly her fingers have begun to cramp.

    Three. Abel. The mech said its name was Abel. We were taught that there are twenty-five models of mech in the Mansfield Cybernetics line, alphabetical from B to Z. A was for a prototype.

    Four. Abel’s face and posture haven’t shifted in the slightest. Would it stand here for an hour? A whole day? At any rate, it hasn’t made any move to get its weapon back.

    Five.

    Noemi grabs Abel’s blaster. “My friend in the docking bay—she needs medical help, now.”

    “Understood. I’ll bring her to sick bay.” Abel takes off down the hallway so quickly that Noemi first thinks it’s escaping—but it’s apparently following her orders, just like it said it would.

    Shoving herself to her feet, Noemi runs after the mech, unwilling to let the thing out of her sight even though she knows she can’t possibly keep up.

    1
    No image caption or credit.

    From Darius Akide’s lectures on mechs, Noemi knows the A model was an experimental model never put into mass production. Could the mech be lying about what it is? Its programming could potentially allow it to lie. But like everyone else on Genesis, she has memorized the faces of every single model of mech. According to her history books, they used to fear infiltration, in the early days of the Liberty War. What if the machines had walked among them, pretending to be human, spying on them all?

    While the Queens and Charlies are most familiar to her, Noemi could identify any of Mansfield’s mechs on sight—and she’s never seen this Abel’s face before.

    Okay, you found a prototype. It doesn’t matter how it got out here as long as you can use it. Take care of Esther and worry about the rest later.

    Her footsteps pound a staccato drumbeat along the corridor as Noemi dashes back to the docking bay. Panting, she stops in the doorway to stare at the scene in front of her. Abel leans over Esther’s damaged fighter, gently scooping her into its arms. Esther’s head lolls back as she murmurs, “Who—who are—”

    “It’s a mech,” Noemi calls as she ditches her nearly dead blaster, then holsters Abel’s to her side. “The ship has a fully equipped sick bay. See? We can take care of you.”

    Abel moves slowly, deliberately, until Esther rests against its chest in a firm embrace. Then Noemi barely has time to get out of the way before it rushes out, moving at a speed no human could match.

    When she gets all the way back up to sick bay, Esther’s lying on a biobed. Abel’s deft fingers move across the controls so swiftly they seem to blur. Noemi goes to Esther’s side and takes her hand.

    “The sensors are still assessing her condition,” Abel reports. “But I predict they’ll confirm preliminary findings of internal bleeding, multiple pelvic fractures, and a mild-to-moderate concussion. If internal bleeding is confirmed, she’ll need an immediate transfusion. I’ve administered pain medication.”

    Enough medication to leave Esther dazed, her eyes half closed and her facial muscles slack—Good, Noemi thinks. Esther needs that. And the nauseous weight in her gut lessens, because those injuries sound survivable. Fixable. At least, if this Abel mech actually knows what it’s doing. “How are you—” She has to stop and gulp in another few breaths before she can continue talking. “You’re one of the medical models? I thought—thought that was the Tare mech.”

    “To the best of my knowledge, the Tare mech remains the primary medical model,” Abel says, as amiably as if they were having tea. The ozone-seared air still stinks of their battle only minutes before. “However, I am programmed with the knowledge, skills, and specialties of the entire Mansfield Cybernetics line.” It glances over from the readouts to study Noemi’s face for a moment. “You’re experiencing extreme shortness of breath. This shouldn’t represent an emergency unless you have any underlying medical conditions. Do you?”

    “What? No.” It’s so strange, talking to a mech. Standing beside one. It feels just like standing next to a person, even though nothing could be further from the truth. “I just— pushed myself. That’s all.”

    “You could’ve remained in sick bay instead of following me down,” it points out.

    “I don’t trust you.”

    “I wasn’t asking for a justification for your actions. Humans have many reasons for behaving in an inefficient or irrational manner.” Abel’s tone is so mild that it takes Noemi a moment to recognize the insult.

    But that’s stupid. She’s anthropomorphizing a mech—a recruit’s mistake, one she should be past. Apparently this prototype’s innovations don’t include tact.

    The dark, glistening stuff in the bags Abel brings out must be synthetic blood. He’s very sure about that transfusion. Some faiths on Genesis won’t use synthetic blood, others won’t accept transfusions at all, but Esther’s family doesn’t belong to one of those.

    Noemi imagines the Gatsons standing before her, tall and pale, their expressions disapproving. How could you let this happen? they might say. You were supposed to protect our daughter. After everything we did for you, how could you let her be hurt?

    Smoothly, the mech slips the needle into Esther’s skin. Not a flicker of discomfort shows on her face. Is she that doped up, or is the mech that good? Probably both, Noemi decides. While Abel works, she studies its—his face in greater depth. There really is something different about this one. He looks younger than most mechs, as if he’s perhaps two or three years older she is. Instead of the customary, blandly appealing mech features, he has a distinctive face with piercing blue eyes, a strong nose, and, if she recalls correctly, a slightly asymmetrical smile.

    Why make a mech so … specific? And so advanced? Akide had told them that mechs were calibrated to the level of intelligence they required for their duties, nothing more. Extra intelligence would only be a complication, another way for a mech to break down. There were even laws against developing mech intelligence too far, or there had been, the last anyone on Genesis heard about Earth laws. If Abel is telling her the truth—and by now she believes he is—he represents a significant step forward in cybernetics development.

    Except that he can’t be. This ship was abandoned many years ago. As she brushes a strand of hair away from Esther’s cheek, Noemi asks, “How long have you been aboard the Daedalus?”

    “Not quite thirty years,” Abel says. “I can provide the exact time down to the nanosecond if required.”

    “It isn’t.” It so, so isn’t.

    “I doubted it would be.” Abel turns away from the medical readouts to face her directly. “Upon further examination, the patient’s liver appears to be ruptured, and the internal bleeding is more severe than initially indicated. Surgery will be required.”

    Noemi’s abdomen knots in sympathetic pain. “But—if Esther loses her liver, she won’t survive.”

    Abel walks away from the biobed, toward various storage chambers—even past a few cryosleep pods against the wall. “The Daedalus is stocked with artificial organs in case emergency transplants are needed.”

    She bites her lower lip. Although Genesis has retained more medical technology than any other kind, artificial organs are used very rarely. Yes, life is precious and must be preserved, but death is accepted as a part of life. Unnaturally avoiding death is seen as an act of futility, sometimes even one of cowardice. The Gatsons are particularly strict about these things. They spent weeks debating whether or not Mr. Gatson should even have laser surgery on his eyes.

    This is different. Esther’s only seventeen! She was injured trying to protect our world. Noemi didn’t sign up for the Masada Run only to have Esther die anyway. “All right,” she says. “All right. Do it.”

    From the biobed comes a whisper: “Don’t.”

    Noemi looks down to see Esther gazing up. Her skin, always fair, has turned waxen. One of her pale green eyes is horribly marred, deep red where it ought to be white. But she’s awake.

    “It’s okay.” Noemi tries to smile. “I’m here. Do you need more pain meds?”

    “It doesn’t hurt.” Esther sighs deeply. Her eyelids droop, but for only a moment. She’s fighting so hard to stay awake. “No transplant.”

    It’s like the chill of space outside the ship’s hull rushed in to freeze Noemi’s blood. She feels adrift, exposed, vulnerable. Like she’s the one in mortal danger instead of Esther. “No, no, it’s all right. This is an emergency—”

    “It would make me part machine. That isn’t human life. Not the life I was given.”

    Please, God, no. God doesn’t speak to Noemi’s heart, no matter how often she prays for guidance. But maybe he’ll speak to Esther’s. Show her it’s more important to stay alive no matter what. The Gatsons raised them so strictly, and Esther’s always obeyed her parents. Now, though—who could argue with this?

    “Esther, please.” Noemi’s voice has begun to shake. “If you don’t have the transplant, you’ll die.”

    “I know.” Esther feebly moves her hand, searching for Noemi’s; Noemi takes it and hangs on tight. Esther’s skin is growing cold. “I knew as soon as the mech tore through my ship. Please—don’t argue while we’re saying good-bye—”

    “To hell with good-bye!” Noemi will make this up to Esther later. “You. Abel. Perform the transplant.”

    Abel, who’s been standing in the middle of sick bay through this entire conversation, shakes his head no. “I’m sorry, but I can’t.”

    “You just said you had all the talents of every mech ever! Were you lying?”

    “I don’t mean that I am incapable of performing the transplant.” If she didn’t know better, she’d think Abel was offended. “And I cannot lie to you, as my commander.”

    “That’s right. I’m your commander.” Noemi seizes onto this, the one weapon she has that might make Abel stop arguing and move, dammit. “So you have to follow my orders, and I’m ordering you to perform the transplant.”

    “Noemi—” Esther whispers. The weakness in her voice slices through Noemi like a blade, but she doesn’t let herself look away from the mech. Abel is Esther’s only hope.

    He doesn’t take a single step closer as he says, “Your authority over me is subject to a few strictly limited exceptions. One of those exceptions is that I must obey the wishes of a medical patient regarding end-of-life decisions. Esther’s choice is therefore final.”

    2
    No image caption or credit.

    Damn, damn, damn! The same programming that saved her life is endangering Esther’s. Why would Mansfield build legions of killing machines and then program them with mock morality? Just one more way the people of Earth fool themselves into accepting the machines in their midst, like the human skin and hair. Noemi wants to scream at Abel but knows it would do no good. Programming is final. Absolute.

    Instead she bends closer to Esther, brushing her friend’s pale-gold hair away from her face. “If you won’t do it for yourself, then do it for me. We’re on this spaceship out in the middle of nowhere, and I need your help to—to—”

    But it’s not help she needs. It’s Esther herself. Noemi knows she’s only made one real friend in her life, but she only ever needed one, because it was Esther, who knew every awful thing about her and loved her anyhow. Noemi’s bad temper and awkwardness and distrust—the same stuff that pushed Mr. and Mrs. Gatson and Jemuel and everybody else away—Esther was the only person who didn’t think those things mattered. The only one who ever would.

    A sob bubbles up in Noemi’s throat, but she chokes it back to whisper, once again, “Please. You’re supposed to be the one who goes back. You’re the one who’s going to make it.” The one who can be happy. The one who can be good, who can love and be loved. Noemi can only be the one left over.

    “You were willing to die for me,” Esther says. For one moment she’s really able to focus on Noemi; maybe the blood flowing into her is helping a little. “At least now you won’t have to. Not if you take your name off the list. You can now. Promise me you will.”

    “Esther—”

    “Tell Mom and Dad I love them.”

    Abel chooses this moment to interrupt. “I had a thought.”

    “Is it about getting around your idiotic programming?” Noemi snaps. Oh, why did she have to say it like that? She doesn’t want Esther to hear her being mean, not now.

    “Cryosleep.” Abel points at the pods against the wall. “Often even severely injured people can be successfully put into cryosleep. If she weren’t brought out of it until an organ could be cloned, perhaps—”

    Esther wouldn’t agree to cloning either, but cryosleep would be okay. What they’d do after that … Noemi doesn’t have to think of that now. She can leave it to the doctors once they’re back on Genesis. “Yes! Please, yes, put her in cryosleep!”

    “I’ll check on the pods.” Abel’s on it in an instant, finally making himself useful again. But after a few moments, he pauses. “I’m afraid the cryosleep pods’ power source was damaged in the attack on the Daedalus thirty years ago.”

    “Isn’t there any way around it?” On a ship this size, Noemi knows, every vital system should have backup.

    “Normally the ship’s main grid would provide backup power, but I took that offline.”

    “I thought you were supposed to be helping me!”

    “I am now,” Abel says, his tone maddeningly even. “I wasn’t when you first boarded the ship. At that point you were considered an intruder and—”

    “It doesn’t matter!” Noemi’s almost screaming by now, and she doesn’t care. “Just bring the main grid back up!”

    Abel nods and rushes toward sick bay’s main computer interface. Noemi takes a deep breath to steady herself before she leans back down toward Esther. “It’s going to be all right,” she whispers. “We’ve got a plan now. …”

    Esther’s eyes are closed. She doesn’t hear. Noemi looks up at the biobed and sees the dark truth the sensors reveal: Esther is dying. Right now. This moment.

    “Esther?” Noemi touches her friend’s shoulder, stricken. “Can you hear me?”

    Nothing.

    Please, God, please, if you won’t give me anything else, at least let me tell her good-bye. He’s never answered Noemi before, but if he does now, she’ll believe forever. I have to tell her good-bye.

    The sensors flatline. Esther is gone.

    In the very next instant, every computer interface in sick bay brightens to full illumination. The damned mech brought power back online just as soon as it was too late to save Esther.

    Noemi stands as if frozen, staring down at Esther. Her eyes well with tears, but it’s like they’re crying without her. Instead of sobbing or shaking, she feels as if she’ll never move again.

    She’s in heaven now. Noemi should believe that. She does, mostly, but the knowledge doesn’t comfort her. The words only echo in the hollow space that has replaced her heart. She finds herself remembering her family’s funeral more vividly than she has in years—the high winds that blew, tugging at everyone’s hair and clothes, and stealing the priest’s words before Noemi could really hear them. The way Noemi stared down into the grave and tried to imagine her parents lying there, baby Rafael between them, looking up at the sky for the last time before they were covered by dirt forever. More than anything else, she remembers Esther standing near her, all in black, crying as hard and loud as Noemi herself. Years later Esther had revealed that she made herself cry, so Noemi wouldn’t be alone.

    Now Esther’s gone, too, and instead of being held close and told she was loved, she had to die listening to Noemi shriek at someone in anger. That ugly moment was the last one Esther ever knew.

    It’s dangerous—being angry at God—but Noemi can’t deny the bitter rage she feels at this one last proof that she isn’t enough for God, for the Gatsons, for anyone at all.

    The long silence is broken by Abel’s voice. “I didn’t attempt resuscitation because failure was all but certain. Her internal blood loss was too great. We would’ve had to begin the transfusion much earlier to save her.”

    “Or we could’ve gotten her into cryosleep.” Noemi turns to stare at the mech. He stands near the computer interface, very still, so obviously unsure what to do that he looks almost human. This doesn’t move her; it enrages her. “If you hadn’t wasted time trying to kill me, Esther might still be alive! We could have put her into cryosleep and saved her!”

    Abel doesn’t respond at first. But finally he says, “You are correct.”

    As many times as Noemi has gone into battle against Earth forces—as many times as she’s seen friends and fellow soldiers torn apart by their mechs—she thought she knew how to hate with her whole heart. But she didn’t.

    Now, only now, as she stares at the machine responsible for her best friend’s death, does Noemi feel what hatred really is.

    Abel’s programming covers many situations involving interpersonal conflict.

    Not this one.

    The Genesis warrior—the dead one called her Noemi—stands next to the corpse, shaking with anger. Like all mechs, he has been constructed to endure human wrath in both its emotional and physical forms, and yet he finds himself uncertain. Wary. Even … worried.

    Noemi has command over him unless and until he is released by someone with the authority to override her. Therefore, her power over him is all but absolute. It doesn’t matter that he could outrun her, outshoot her, that he could kill her with a single hand: He cannot defend himself against her any more than he can disobey her. Abel is at his commander’s mercy.

    She takes a deep breath, stops trembling, and goes very still. He isn’t sure how, but he knows that’s worse.

    “Where’s the nearest air lock?” Noemi asks.

    “The equipment pod bay approximately halfway down the main ship’s corridor.” In other words, the cell in which Abel just spent the past three decades. Noemi seems unlikely to be interested in this information, so he says nothing else.

    Noemi nods. “Walk toward it.”

    Abel does so. She follows a few steps behind. Although she could potentially have many reasons for needing an air lock, he immediately understands which of her potential purposes is most likely—namely, his destruction. She will release him into the cold void of space, where he will cease operations.

    Not instantaneously. Abel is built to withstand even the near-absolute-zero temperatures of outer space … for a time. But within seven to ten minutes, the damage to his organic tissues will be permanent. Total mechanical malfunction will swiftly follow.

    He isn’t afraid to die. And yet, as he walks along the corridor to his doom, his executioner’s steps echoing behind him, Abel feels that this is wrong. Unjust, somehow.

    Is this another of his strange emotional malfunctions? Perhaps his pride is occupying too large a part of his thoughts, because it galls Abel to think that he—the most complex mech ever created—is about to be tossed out an air lock like human refuse, for no reason other than the pique of an unhappy Genesis soldier.

    After some consideration, he decides that yes, his pride is interfering with effective analysis of the situation. He is from Earth, and therefore he is this girl’s enemy. Although he knows how powerfully his programming controls him, she probably doesn’t trust it. If Genesis has held true to its anti-technology stance, then Noemi has probably never been in the same room with a mech before. She’d only have met them in battle. No wonder she finds him frightening. Taking into account the fact that he attacked and very nearly killed her not half an hour before, her decision to space him appears more reasonable. Almost logical.

    That doesn’t make him feel any better about it.

    When Abel reaches the equipment pod bay, he steps without hesitation through the door he was so grateful to escape not even an hour ago. He can see the irony of having been freed from this place only to come back here to die. In his mind he finds himself running through scenarios, possibilities—the seven different ways he could kill the Genesis soldier this instant. Why?

    Then Abel realizes what it is: It’s not that he doesn’t want to die. It’s that he wants to live.

    He wants more time. To learn more things, to travel through the galaxy and see all the colony worlds of the Loop, to return back home to Earth for at least one day. To find out what has become of Burton Mansfield and perhaps speak with his “father” once more. To watch Casablanca properly again instead of merely retelling himself the story. To ask more questions, even if he never gets the answers.

    But what a mech wants doesn’t matter.

    3
    No image caption or credit.

    Abel turns to face Noemi before she can hit the controls that will seal this door, allowing her to open the outer hatch and vent him into space. He went so long without seeing a human face or speaking to anyone. It helps him to look at her, even if that means watching her take the steps that will kill him. Although he doesn’t expect this to affect her in any way, her dark-brown eyes widen when they’re face-to-face again.

    Noemi doesn’t speak. She lifts her hand to the control panel … and does nothing.

    Seconds tick by. When Abel judges that this pause has gone on an inordinately long time, he ventures, “Do you need help understanding the controls?”

    “I understand the controls.” Her voice is thick from the tears she’s still holding back.

    Abel cocks his head. “Have I misinterpreted your purpose in bringing me here?”

    “What do you think my purpose is?”

    “To space me.”

    “You got it.” Her smile is twisted by grief. “That’s why we came here.”

    “Then may I ask why you have not yet done so?”

    “Because it’s stupid,” Noemi says. “Hating you. I want to hate you because you might’ve saved Esther and you didn’t—but what’s the point? You’re not a person. You don’t have a soul. You obey your programming, because you have to, and without free will there can be no sin.” She breathes out sharply in frustration, looks up at the ceiling as if that will keep the tears from trickling beyond her eyes. “I might as well hate a wheel.”

    A few more seconds elapse before Abel feels emboldened to say, “May I now step out of the air lock door?”

    Noemi moves back, making room for him. This reads as permission, and so Abel steps out of the equipment pod bay with profound relief. Only then does Noemi hit the controls, once again sealing off the bay.

    He offers, “If you would feel safer with me immobilized, the cryosleep pods would be effective. Mechs cannot be put in true cryosleep, but exposure to the chemicals activates our dormant mode.”

    “I don’t need you to be dormant. I need you to be useful.” She wipes at her eyes, attempts to act like the soldier she is. “We’ll—I’ll take care of Esther later. First I have to make a plan. Wasn’t the bridge back that way?”

    “Yes, ma’am.”

    She winces. “Please don’t call me that.”

    “How should I address you?”

    She’s still pulling herself together. “My name is Noemi Vidal.”

    “Yes, Captain Vidal.”

    “Noemi’s fine.” She turns and trudges toward the bridge. Her voice is hoarse, her exhaustion and grief obvious, but she remains focused on survival. “Follow me, Abel.”

    She’ll let me use her first name, Abel thinks. No human being has ever allowed him that much liberty before. The thought pleases him, though he can’t determine why.

    Nor does he know the reason why he glances over his shoulder, back at the equipment pod bay he has escaped twice today. Surely after thirty years he has seen enough of it.

    Perhaps it’s just because it feels so good to leave that place behind.

    This is the navigational position for the pilot, right?” Noemi runs her hands through her hair as they stand on the Daedalus’ bridge. The curved walls allow the ship’s viewscreen to wrap almost entirely around and above them, displaying the surrounding starfield in such detail that the bridge appears to be a dull metallic platform in the middle of outer space. “The captain’s chair is obvious, and I figure this is for external communications. And that’s the ops station.”

    “Correct. Your technological sophistication is surprising for a soldier of Genesis.”

    She turns toward him, frowning. “We limit technology by choice, not out of ignorance.”

    “Of course. But in time, the first must inevitably lead to the second.”

    “Why do you have to act so superior?”

    Abel considers her assertion. “I am superior, in most respects.”

    Noemi’s hands close around the back of the captain’s chair, gripping it too hard, and when she speaks again, she grinds out every word. “Could you. Knock it. Off.”

    “Modesty is not one of my chief operating modes,” he admits, “but I will try.”

    She sighs. “I’ll take what I can get.”

    4
    No image caption or credit.

    He assesses her as she paces the length of the bridge, her formfitting emerald-green exosuit outlining her athletic body vividly against the blackness of space. Amid the stars glow the larger, gently shaded planets of the Genesis system. Abel can make out the circle that is Genesis itself, brilliant green and blue, with its two moons visible as tiny pinpoints of white.

    “Do we have fuel?” Noemi asks. “Can the Daedalus get back home?”

    Abel replies, “Fuel stores are sufficient for full-ship operations lasting two years, ten months, five days, ten hours, and six minutes.” He leaves out the seconds and milliseconds. “The ship took damage in its final battle, but the damage doesn’t appear to have been extreme.” Hardly even threatening. He frowns at the readouts scrolling past on the console. Did Captain Gee panic? Did she convince Mansfield to abandon ship when there was no real need? “Travel through a Gate would be difficult—”

    “We’re not going through a Gate. We’re going home.”

    Of course. Earth is Abel’s home, not Noemi’s. He continues, “After minor repairs with instruments we have on hand, we should be able to reach Genesis without difficulty.”

    “Good.”

    What will become of him on Genesis? Will he be dismantled? Sent back out into space? Made to serve in their armies? Abel cannot guess, and thinks it would be a bad idea to ask. He has no control over the situation. He may as well learn his fate when it comes to pass.

    Noemi sits heavily in the nearest chair, the one at the ops station, which like all the stations aboard the Daedalus is thickly padded and covered with soft black material. Running her hand along it, she frowns. “Was this some kind of luxury cruiser or something? Regular Earth ships can’t all be like this … can they?”

    “The Daedalus is a research vessel, customized especially for its owner and my creator, Burton Mansfield.”

    “Did you say Burton Mansfield?” She sits up straight and gapes at him. “The Burton Mansfield?”

    At last. It’s good to see Noemi finally responding with appropriate awe. “The founder and architect of the Mansfield Cybernetics line? Yes.”

    He watches for her reaction, anticipating her amazement—and instead sees her scowl. “That son of a bitch. This is his ship? You’re his mech?”

    “… yes.” How dare she call his father such names? But Abel can’t object, so he forces himself not to think of it any longer.

    “I can’t believe it,” Noemi mutters. “You’re telling me Mansfield himself came to this system thirty years ago, and he got away?”

    “All humans aboard abandoned ship,” Abel answers as simply as he can. “As I wasn’t on the bridge at that time, I cannot know how successful their escape was, nor their reasons for abandoning a functional ship.”

    “We scared them. That’s why they ran.” Energized, Noemi gets to her feet and reexamines every station on the bridge, as if it requires further consideration now that she knows who it belongs to. “But why would Burton Mansfield come to the Genesis system to start with? Why would he throw himself into the middle of a war?”

    And there it is—the question Abel had hoped Noemi would not think to ask.

    As long as she’s his commander, he cannot lie to her. However, he has enough discretion to … omit certain facts, as long as her questions are not direct.

    He tries indirection first. “Mansfield had undertaken critical scientific research.”

    “In a war zone? What was he researching?”

    A direct question: Full disclosure is now required. “Mansfield was studying a potential vulnerability in the Gate between Genesis and Earth.”

    Noemi goes very still. She’s realizing the true significance of what she’s found. “By vulnerability—do you mean a potential malfunction, or—tell me, exactly, what?”

    Abel remembers the day Mansfield realized the worst. The endless hours of research and sensor readings required, the immense leap of insight it took for Mansfield to grasp the answer: All of this, Abel now has to deliver to a soldier of Genesis. “By vulnerability, I mean he was investigating a way a Gate could be destroyed.”

    Noemi’s face lights up. Under different circumstances, Abel would be pleased to have brought his commander so much joy. “Did you find one?”

    They ought to have foreseen it, Abel thinks. They shouldn’t have left me here. It was … tactically unwise.

    Because I have no choice but to betray them.

    “Answer me,” Noemi says. “Did you find a way to destroy a Gate?”

    Abel admits, “Yes.”

    He’s lying.

    Noemi knows the mech—Abel—can’t lie to her while she’s his commander, which somehow she is. But the enormity of what he’s said makes it feel like the ship’s gravity is shifting beneath her feet, forcing her off-balance. Her grief for Esther weighs on her too heavily to allow for the sudden, staggering return of hope.

    “How?” She takes one step toward Abel. The viewscreen dome shows re-fog trails of the galaxy’s arm, stretching their glowing tendrils overhead. “How can anyone destroy a Gate?”

    “Gates are capable of creating and stabilizing wormholes, which are essentially shortcuts in space-time,” he begins, talking down to her again. “When a wormhole is fully stable, a ship can travel through, thereby crossing enormous distances in an instant.”

    The Masada Run will destabilize the Genesis Gate, but only for a while. Months, probably. Two or three years, if they’re lucky. Possibly just a matter of weeks. All those lives, including her own, will be spent for the mere chance that Genesis might gain an opportunity to rebuild and rearm itself, to beat their plowshares into swords, and then to plunge back into a war that they almost certainly can’t win.

    Abel continues, “A wormhole can only be permanently stabilized through the use of so-called exotic matter. In the Gates, this exotic matter takes the form of supercooled gases kept even colder than the space beyond it, mere nanokelvins above absolute zero.”

    Colder than outer space. Noemi has tried to imagine that before, but she can’t. The intensity of that chill is beyond any human reckoning.

    Abel continues, “These gases are cooled by magnetic fields generated by several powerful electromagnets that make up the components of the Gate—”

    “But all those components—they’re programmed to reinforce one another. It’s almost impossible to destroy one while the others are backing it up.”

    He cocks his head. “You understand more about the components of a Gate than I would have thought.”

    “What, you thought nobody from Genesis would’ve learned about this?”

    “To judge by the extremely outdated and dilapidated condition of your current ships and armaments, Genesis appears to have all but abandoned scientific and technological advancement.”

    From anyone else, that would be an insult. From Abel, it’s a simple, factual assessment. The insult would’ve been easier to take. “Apparently not, because I understand how a Gate works. Which means I know they’re supposed to be invulnerable. You say they’re not. How do we destroy one?”

    He hesitates, and his reluctance is uncannily genuine. Too genuine, in Noemi’s opinion; Mansfield was showing off with this one. “Most efforts to damage or destroy a Gate are targeted at destroying the magnetic fields inside. However, it is not necessary to destroy the fields to collapse the Gate. Only to disrupt them.”

    Noemi shakes her head. “But we can’t even manage that, not with every component supporting one another.”

    “You’ve failed to see the obvious alternative.” Abel catches himself. “You shouldn’t feel that this failure reflects negatively on you. Relatively few humans are capable of the insight necessary to—”

    “Just tell me.”

    “Disrupting the fields doesn’t have to mean weakening or destroying them. It can also mean strengthening them.”

    She opens her mouth to object. Strengthen it? How can making the Gate stronger possibly help them? Then the answer takes shape in her mind. “Strengthening the fields would warm the gases inside. When the exotic matter becomes too warm, the Gate will implode.”

    Abel inclines his head, not quite a nod. “And destroy the wormhole forever.”

    Noemi sinks into the nearest station, overwhelmed by the possibilities and problems she now sees. “But—any device powerful enough to overcome the Gate’s magnetic fields—where would we get that? Do any of those even exist?”

    “There are thermomagnetic devices capable of creating that level of heat on their own. Not many, of course. The practical applications are limited.”

    “But they are out there? We could find one?”

    “Yes.”

    She wants to hope—wants it so badly she can taste it—but Noemi can see all the problems with this plan already. “You’d have to activate it on the verge of the Gate. Otherwise the heat would melt your ship before you even reach the Gate. And you can’t just launch it remotely either. You’d have to have a pilot to work around the Gate’s defenses.”

    “You understand a great deal about piloting for someone from a planet that has stubbornly refused to go anywhere.”

    And that reminds her of the guilty longings she sometimes feels when she sees the speed of Earth ships, the complexity of the Gate, even the inhuman reflexes of their mechs. Noemi doesn’t want to be like people from Earth, but … she can’t help wanting to know what they know. To discover. To explore.

    Her next flash of insight eclipses all those old dreams in an instant. “No human could do it. A human pilot would lose control or die from the heat too quickly.”

    “True. Also, even if the human pilot could succeed, the Gate’s implosion would kill her instantly.”

    Noemi hadn’t bothered worrying about that. Collapsing the Gate—saving her world—it’s worth one life. Her willingness to make that sacrifice is irrelevant if she would only fail. But there’s another possibility. “A mech could do it, right?”

    Abel hesitates before answering, just long enough for her to be aware of it. “Not most mechs. They’re programmed to go into basic utility mode during self-damaging tasks. You’d need an advanced model. One capable of thinking even at the point of destruction.”

    “An advanced model like you.”

    He straightens. “Yes.”

    Abel clearly has no instinct for self-preservation that overrides the orders given by his commander. The air lock proved that. If she tells him to destroy the Gate and be destroyed along with it, he will.

    Noemi would gladly lay down her life to save Genesis. So she can ask a mech to give up … whatever it is he has.

    Slowly she rises from the chair. The projected starlight shines softly around her, making the moment even more dreamlike than it already is.

    Her only plan had been steering the Daedalus toward Genesis and bringing Esther’s body home. She’d had a vague idea of turning the ship and the mech over to her superior officers, in case they could be used in the war effort. Some small contributions that would outlive her, that could go on serving after the Masada Run.

    Instead she’s found a mech not only aware of how to destroy a Gate but also capable of helping her do it. And a ship that could take her through the Loop to find the device she needs—Earth would come after any Genesis ship, she thinks, but they won’t be on the lookout for this one. This could actually work.

    It means throwing herself through the galaxy, to planets she’s never seen before. It means risking her life, maybe even winding up in an Earth prison, defeated and helpless—which would be so much worse than dying in the Masada Run. It means leaving Genesis behind, maybe forever.

    She turns to Abel. “We’re going to destroy this Gate.”

    “Very well,” he replies as easily as if she’d asked him the time. “We should run an in-depth diagnostic on the Daedalus. Although my initial scans indicate that she remains fully fueled and in good condition, we will want to be certain of that before we begin to travel. It should take no more than an hour or two.”

    It startles her that he understands they’re about to travel through the Gates to other worlds, but of course he does. Abel would’ve realized the implications as soon as he explained the Gate’s flaw to her. However, there’s one thing he doesn’t understand yet. “We have to wait.”

    Abel gives her a look. “So you want to end a deadly and destructive war, but there’s … no rush?”

    Noemi’s not sure why Mansfield decided to give a mech the capacity for sarcasm. “I’m only an ensign,” she says, tapping the single gray stripe on the cuff of her green exosuit sleeve. “This mission—it’s risky, and there could be drawbacks I haven’t seen—”

    “I would have seen them.” His expression is so smug that Noemi wishes she had something in her hands to throw at him.

    “Yeah, well, you’re Burton Mansfield’s mech. So forgive me if I don’t trust you completely.”

    “If you don’t trust me, why are you undertaking this mission on my word alone?” Abel seems almost irritated. “If I could lie to you about the risks, I could also lie to you about the potential.”

    That’s not a bad point, but Noemi doesn’t bother justifying herself to a mech. “My point is, I should run this by my superior officers if I can.”

    “Do you wish to fly directly to Genesis?”
Noemi opens her mouth to give the order, then thinks better of it. Yes, she should run this by Captain Baz at least—probably the whole Elder Council. She can imagine standing in their white marble chamber in her dress uniform, looking up at Darius Akide and the other elders, showing them this one chance they have to save their world.

    And she can imagine them saying no.

    They might not trust Abel’s word. What would it take to convince the Elder Council? They’re so sure the Masada Run is the only way—

    She thinks about the various speeches that have been given, the vids they’ve seen in support of the Masada Run. Sacrifice your lives, they say. Sacrifice your children. Only through sacrifice can Genesis survive.

    Now she’d be coming back to tell all of Genesis and the Council that there’s another way out. That the Masada Run isn’t necessary and never was. She, Noemi Vidal, a seventeen-year-old ensign, orphaned and newly friendless, backed up only by a mech.

    Would the Elder Council even believe her? Worse, would they refuse to back down just to avoid admitting they were wrong?

    It’s not that Noemi never doubted the Council before—but this is the first time she’s ever allowed herself to think that they might fail her world so completely. She’s not sure she really believes they would. But they could, and that risk alone is enough.

    “Belay that order,” she says slowly. “Run the diagnostic. See if the ship’s ready to travel through the Gates.”

    Abel raises one eyebrow. “Does that mean we’re proceeding without approval from your superiors?”

    Noemi’s been taking orders her whole life. From the Gatsons, because they were good enough to take her into their family and deserved her obedience. From her teachers, from her commanding officers. She’s tried to obey all of them and the Word of God, too, despite all her doubts and confusion, putting aside her own dreams, because that’s her duty.

    But her duty to protect Genesis goes beyond any of that.

    “Yes,” Noemi says, staring out at the stars that will guide her. “We’re going to destroy the Gate on our own.”

    To save her world, she must learn to stand alone.

    See the full article here .

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