Tagged: Physics Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 2:58 pm on June 30, 2016 Permalink | Reply
    Tags: , JQI, Physics, Solitons   

    From JQI: “Ultra-cold atoms may wade through quantum friction” 

    JQI bloc

    Joint Quantum Institute

    June 24, 2016

    Research Contact
    Dmitry Efimkin

    Victor Galitski

    Johannes Hofmann

    Media Contact
    Chris Cesare

    A soliton made of atoms rolls like a marble in a one-dimensional trap created by lasers. Credit: S. Kelley/NIST

    Theoretical physicists studying the behavior of ultra-cold atoms have discovered a new source of friction, dispensing with a century-old paradox in the process. Their prediction, which experimenters may soon try to verify, was reported recently in Physical Review Letters.

    The friction afflicts certain arrangements of atoms in a Bose-Einstein Condensate (BEC), a quantum state of matter in which the atoms behave in lockstep. In this state, well-tuned magnetic fields can cause the atoms to attract one another and even bunch together, forming a single composite particle known as a soliton.

    Solitons appear in many areas of physics and are exceptionally stable. They can travel freely, without losing energy or dispersing, allowing theorists to treat them like everyday, non-quantum objects. Solitons composed of photons—rather than atoms—are even used for communication over optical fibers.

    Studying the theoretical properties of solitons can be a fruitful avenue of research, notes Dmitry Efimkin, the lead author of the paper and a former JQI postdoctoral researcher now at the University of Texas at Austin. “Friction is very fundamental, and quantum mechanics is now quite a well-tested theory,” Efimkin says. “This work investigates the problem of quantum friction for solitons and marries these two fundamental areas of research.”

    Efimkin, along with JQI Fellow Victor Galitski and Johannes Hofmann, a physicist at the University of Cambridge, sought to answer a basic question about soliton BECs: Does an idealized model of a soliton have any intrinsic friction?

    Prior studies seemed to say no. Friction arising from billiard-ball-like collisions between a soliton and stray quantum particles was a possibility, but the mathematics prohibited it. For a long time, then, theorists believed that the soliton moved through its cloudy quantum surroundings essentially untouched.

    But those prior studies did not give the problem a full quantum consideration, Hofmann says. “The new work sets up a rigorous quantum-mechanical treatment of the system,” he says, adding that this theoretical approach is what revealed the new frictional force.

    It’s friction that is familiar from a very different branch of physics. When a charged particle, such as an electron, is accelerated, it emits radiation. A long-known consequence is that the electron will experience a friction force as it is accelerated, caused by the recoil from the radiation it releases.

    Instead of being proportional to the speed of the electron, as is friction like air resistance, this force instead depends on the jerk—the rate at which the electron’s acceleration is changing. Intriguingly, this is the same frictional force that appears in the quantum treatment of the soliton, with the soliton’s absorption and emission of quantum quasiparticles replacing the electron’s emission of radiation.

    Infographic credit: S. Kelley/NIST and C. Cesare/JQI

    At the heart of this frictional force, however, lurks a problem. Including it in the equations describing the soliton’s motion—or an accelerated electron’s—reveals that the motion in the present depends on events in the future, a result that inverts the standard concept of causality. It’s a situation that has puzzled physicists for decades.

    The team tracked down the origin of these time-bending predictions and dispensed with the paradox. The problem arises from a step in the calculation that assumes the friction force only depends on the current state of the soliton. If, instead, it also depends on the soliton’s past trajectory, the paradox disappears.

    Including this dependence on the soliton’s history leads to nearly the same equations governing its motion, and those equations still include the new friction. It’s as if the quantum background retains a memory of the soliton’s path.

    Hofmann says that BECs provide a pristine system to search for the friction. Experimenters can apply lasers that set the atomic soliton in motion, much like a marble rolling around a bowl—although the bowl is tightly squeezed in one dimension. Observing the frequency and amplitude of this motion, as well as how it changes over time, could reveal the friction’s signature. “Using some typical experimental parameters, we think that the magnitude of this force is large enough to be observable in current experiments,” Hofmann says.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    We are on the verge of a new technological revolution as the strange and unique properties of quantum physics become relevant and exploitable in the context of information science and technology.

    The Joint Quantum Institute (JQI) is pursuing that goal through the work of leading quantum scientists from the Department of Physics of the University of Maryland (UMD), the National Institute of Standards and Technology (NIST) and the Laboratory for Physical Sciences (LPS). Each institution brings to JQI major experimental and theoretical research programs that are dedicated to the goals of controlling and exploiting quantum systems.

    See the full article here .

  • richardmitnick 5:53 pm on June 26, 2016 Permalink | Reply
    Tags: , Lawrence Krauss, Philosophy and Religion, Physics   

    From The Atlantic: “Has Physics Made Philosophy and Religion Obsolete?” 2012 but Very Important 

    Atlantic Magazine

    The Atlantic Magazine

    Apr 23, 2012
    Ross Andersen

    No image caption. No image credit.

    It is hard to know how our future descendants will regard the little sliver of history that we live in. It is hard to know what events will seem important to them, what the narrative of now will look like to the twenty-fifth century mind. We tend to think of our time as one uniquely shaped by the advance of technology, but more and more I suspect that this will be remembered as an age of cosmology—as the moment when the human mind first internalized the cosmos that gave rise to it. Over the past century, since the discovery that our universe is expanding, science has quietly begun to sketch the structure of the entire cosmos, extending its explanatory powers across a hundred billion galaxies, to the dawn of space and time itself. It is breathtaking to consider how quickly we have come to understand the basics of everything from star formation to galaxy formation to universe formation. And now, equipped with the predictive power of quantum physics, theoretical physicists are beginning to push even further, into new universes and new physics, into controversies once thought to be squarely within the domain of theology or philosophy.

    In January, Lawrence Krauss, a theoretical physicist and Director of the Origins Institute at Arizona State University, published A Universe From Nothing: Why There Is Something Rather Than Nothing, a book that, as its title suggests, purports to explain how something—and not just any something, but the entire universe—could have emerged from nothing, the kind of nothing implicated by quantum field theory. But before attempting to do so, the book first tells the story of modern cosmology, whipping its way through the big bang to microwave background radiation and the discovery of dark energy. It’s a story that Krauss is well positioned to tell; in recent years he has emerged as an unusually gifted explainer of astrophysics. One of his lectures has been viewed over a million times on YouTube and his cultural reach extends to some unlikely places—last year Miley Cyrus came under fire when she tweeted a quote from Krauss that some Christians found offensive. Krauss’ book quickly became a bestseller, drawing raves from popular atheists like Sam Harris and Richard Dawkins, the latter of which even compared it to The Origin of Species for the way its final chapters were supposed to finally upend the “last trump card of the theologian.”

    By early spring, media coverage of A Universe From Nothing seemed to have run its course, but then on March 23rd the New York Times ran a blistering review of the book, written by David Albert, a philosopher of physics from Columbia University. Albert, who has a PhD in theoretical physics, argued that Krauss’ “nothing” was in fact a something and did so in uncompromising terms:

    “The particular, eternally persisting, elementary physical stuff of the world, according to the standard presentations of relativistic quantum field theories, consists (unsurprisingly) of relativistic quantum fields… they have nothing whatsoever to say on the subject of where those fields came from, or of why the world should have consisted of the particular kinds of fields it does, or of why it should have consisted of fields at all, or of why there should have been a world in the first place. Period. Case closed. End of story.”

    Because the story of modern cosmology has such deep implications for the way that we humans see ourselves and the universe, it must be told correctly and without exaggeration—in the classroom, in the press and in works of popular science. To see two academics, both versed in theoretical physics, disagreeing so intensely on such a fundamental point is troubling. Not because scientists shouldn’t disagree with each other, but because here they’re disagreeing about a claim being disseminated to the public as a legitimate scientific discovery. Readers of popular science often assume that what they’re reading is backed by a strong consensus. Having recently interviewed Krauss for a different project, I reached out to him to see if he was interested in discussing Albert’s criticisms with me. He said that he was, and mentioned that he would be traveling to New York on April 20th to speak at a memorial service for Christopher Hitchens. As it happened, I was also due to be in New York that weekend and so, last Friday, we were able to sit down for the extensive, and at times contentious, conversation that follows.

    I know that you’re just coming from Christopher Hitchens’ memorial service. How did that go?

    Krauss: It was a remarkable event for a remarkable man, and I felt very fortunate to be there. I was invited to give the opening presentation in front of all of these literary figures and dignitaries of various sorts, and so I began the only way I think you can begin, and that’s with music from Monty Python. That got me over my initial stage fright and my concern about what to say about someone as extraordinary as Christopher. I was able to talk about a lot of the aspects of Christopher that people may not know about, including the fact that he was fascinated by science. And I also got to talk about what it felt like to be his friend.

    I closed with an anecdote, a true story about the last time I was with him. I was reading the New York Times at his kitchen table, and there was an article about the ongoing effort to keep Catholic students at elite colleges like Yale from losing their faith. The article said something like “faced with Nietzsche, coed dorms, Hitchens, and beer pong, students are likely to stray.” There are two really amazing aspects of that. For one, to be so culturally ubiquitous that you can be mentioned in a sentence like that without any further explanation is pretty exceptional. But also to be sandwiched between “Nietzsche” and “beer pong” is an honor that very few of us can ever aspire to.

    I want to start with a general question about the relationship between philosophy and physics. There has been a fair amount of sniping between these two disciplines over the past few years. Why the sudden, public antagonism between philosophy and physics?

    Krauss: That’s a good question. I expect it’s because physics has encroached on philosophy. Philosophy used to be a field that had content, but then “natural philosophy” became physics, and physics has only continued to make inroads. Every time there’s a leap in physics, it encroaches on these areas that philosophers have carefully sequestered away to themselves, and so then you have this natural resentment on the part of philosophers. This sense that somehow physicists, because they can’t spell the word “philosophy,” aren’t justified in talking about these things, or haven’t thought deeply about them—

    Is that really a claim that you see often?

    Krauss: It is. Philosophy is a field that, unfortunately, reminds me of that old Woody Allen joke, “those that can’t do, teach, and those that can’t teach, teach gym.” And the worst part of philosophy is the philosophy of science; the only people, as far as I can tell, that read work by philosophers of science are other philosophers of science. It has no impact on physics what so ever, and I doubt that other philosophers read it because it’s fairly technical. And so it’s really hard to understand what justifies it. And so I’d say that this tension occurs because people in philosophy feel threatened, and they have every right to feel threatened, because science progresses and philosophy doesn’t.

    Lawrence Krauss, author of A Universe From Nothing: Why There Is Something Rather Than Nothing

    On that note, you were recently quoted as saying that philosophy “hasn’t progressed in two thousand years.” But computer science, particularly research into artificial intelligence was to a large degree built on foundational work done by philosophers in logic and other formal languages. And certainly philosophers like John Rawls have been immensely influential in fields like political science and public policy. Do you view those as legitimate achievements?

    Krauss: Well, yeah, I mean, look I was being provocative, as I tend to do every now and then in order to get people’s attention. There are areas of philosophy that are important, but I think of them as being subsumed by other fields. In the case of descriptive philosophy you have literature or logic, which in my view is really mathematics. Formal logic is mathematics, and there are philosophers like Wittgenstein that are very mathematical, but what they’re really doing is mathematics—it’s not talking about things that have affected computer science, it’s mathematical logic. And again, I think of the interesting work in philosophy as being subsumed by other disciplines like history, literature, and to some extent political science insofar as ethics can be said to fall under that heading. To me what philosophy does best is reflect on knowledge that’s generated in other areas.

    I’m not sure that’s right. I think that in some cases philosophy actually generates new fields. Computer science is a perfect example. Certainly philosophical work in logic can be said to have been subsumed by computer science, but subsumed might be the wrong word—

    Krauss: Well, you name me the philosophers that did key work for computer science; I think of John Von Neumann and other mathematicians, and—

    But Bertrand Russell paved the way for Von Neumann.

    Krauss: But Bertrand Russell was a mathematician. I mean, he was a philosopher too and he was interested in the philosophical foundations of mathematics, but by the way, when he wrote about the philosophical foundations of mathematics, what did he do? He got it wrong.

    But Einstein got it wrong, too—

    Krauss: Sure, but the difference is that scientists are really happy when they get it wrong, because it means that there’s more to learn. And look, one can play semantic games, but I think that if you look at the people whose work really pushed the computer revolution from Turing to Von Neumann and, you’re right, Bertrand Russell in some general way, I think you’ll find it’s the mathematicians who had the big impact. And logic can certainly be claimed to be a part of philosophy, but to me the content of logic is mathematical.

    Do you find this same tension between theoretical and empirical physics?

    Krauss: Sometimes, but it shouldn’t be there. Physics is an empirical science. As a theoretical physicist I can tell you that I recognize that it’s the experiment that drives the field, and it’s very rare to have it go the other way; Einstein is of course the obvious exception, but even he was guided by observation. It’s usually the universe that’s surprising us, not the other way around.

    Moving on to your book “A Universe From Nothing,” what did you hope to accomplish when you set out to write it?

    Krauss: Every time I write a book, I try and think of a hook. People are interested in science, but they don’t always know they’re interested in science, and so I try to find a way to get them interested. Teaching and writing, to me, is really just seduction; you go to where people are and you find something that they’re interested in and you try and use that to convince them that they should be interested in what you have to say.

    The religious question “why is there something rather than nothing,” has been around since people have been around, and now we’re actually reaching a point where science is beginning to address that question. And so I figured I could use that question as a way to celebrate the revolutionary changes that we’ve achieved in refining our picture of the universe. I didn’t write the book to attack religion, per se. The purpose of the book is to point out all of these amazing things that we now know about the universe. Reading some of the reactions to the book, it seems like you automatically become strident the minute you try to explain something naturally.

    Richard Dawkins wrote the afterword for the book—and I thought it was pretentious at the time, but I just decided to go with it—where he compares the book to The Origin of Species. And of course as a scientific work it doesn’t some close to The Origin of Species, which is one of the greatest scientific works ever produced. And I say that as a physicist; I’ve often argued that Darwin was a greater scientist than Einstein. But there is one similarity between my book and Darwin’s—before Darwin life was a miracle; every aspect of life was a miracle, every species was designed, etc. And then what Darwin showed was that simple laws could, in principle, plausibly explain the incredible diversity of life. And while we don’t yet know the ultimate origin of life, for most people it’s plausible that at some point chemistry became biology. What’s amazing to me is that we’re now at a point where we can plausibly argue that a universe full of stuff came from a very simple beginning, the simplest of all beginnings: nothing. That’s been driven by profound revolutions in our understanding of the universe, and that seemed to me to be something worth celebrating, and so what I wanted to do was use this question to get people to face this remarkable universe that we live in.

    Your book argues that physics has definitively demonstrated how something can come from nothing. Do you mean that physics has explained how particles can emerge from so-called empty space, or are you making a deeper claim?

    Krauss: I’m making a deeper claim, but at the same time I think you’re overstating what I argued. I don’t think I argued that physics has definitively shown how something could come from nothing; physics has shown how plausible physical mechanisms might cause this to happen. I try to be intellectually honest in everything that I write, especially about what we know and what we don’t know. If you’re writing for the public, the one thing you can’t do is overstate your claim, because people are going to believe you. They see I’m a physicist and so if I say that protons are little pink elephants, people might believe me. And so I try to be very careful and responsible. We don’t know how something can come from nothing, but we do know some plausible ways that it might.

    But I am certainly claiming a lot more than just that. That it’s possible to create particles from no particles is remarkable—that you can do that with impunity, without violating the conservation of energy and all that, is a remarkable thing. The fact that “nothing,” namely empty space, is unstable is amazing. But I’ll be the first to say that empty space as I’m describing it isn’t necessarily nothing, although I will add that it was plenty good enough for Augustine and the people who wrote the Bible. For them an eternal empty void was the definition of nothing, and certainly I show that that kind of nothing ain’t nothing anymore.

    But debating physics with Augustine might not be an interesting thing to do in 2012.

    Krauss: It might be more interesting than debating some of the moronic philosophers that have written about my book. Given what we know about quantum gravity, or what we presume about quantum gravity, we know you can create space from where there was no space. And so you’ve got a situation where there were no particles in space, but also there was no space. That’s a lot closer to “nothing.”

    But of course then people say that’s not “nothing,” because you can create something from it. They ask, justifiably, where the laws come from. And the last part of the book argues that we’ve been driven to this notion—a notion that I don’t like—that the laws of physics themselves could be an environmental accident. On that theory, physics itself becomes an environmental science, and the laws of physics come into being when the universe comes into being. And to me that’s the last nail in the coffin for “nothingness.”

    It sounds like you’re arguing that ‘nothing’ is really a quantum vacuum, and that a quantum vacuum is unstable in such a way as to make the production of matter and space inevitable. But a quantum vacuum has properties. For one, it is subject to the equations of quantum field theory. Why should we think of it as nothing?

    Krauss: That would be a legitimate argument if that were all I was arguing. By the way it’s a nebulous term to say that something is a quantum vacuum in this way. That’s another term that these theologians and philosophers have started using because they don’t know what the hell it is, but it makes them sound like they know what they’re talking about. When I talk about empty space, I am talking about a quantum vacuum, but when I’m talking about no space whatsoever, I don’t see how you can call it a quantum vacuum. It’s true that I’m applying the laws of quantum mechanics to it, but I’m applying it to nothing, to literally nothing. No space, no time, nothing. There may have been meta-laws that created it, but how you can call that universe that didn’t exist “something” is beyond me. When you go to the level of creating space, you have to argue that if there was no space and no time, there wasn’t any pre-existing quantum vacuum. That’s a later stage.

    Even if you accept this argument that nothing is not nothing, you have to acknowledge that nothing is being used in a philosophical sense. But I don’t really give a damn about what “nothing” means to philosophers; I care about the “nothing” of reality. And if the “nothing” of reality is full of stuff, then I’ll go with that.

    But I don’t have to accept that argument, because space didn’t exist in the state I’m talking about, and of course then you’ll say that the laws of quantum mechanics existed, and that those are something. But I don’t know what laws existed then. In fact, most of the laws of nature didn’t exist before the universe was created; they were created along with the universe, at least in the multiverse picture. The forces of nature, the definition of particles—all these things come into existence with the universe, and in a different universe, different forces and different particles might exist. We don’t yet have the mathematics to describe a multiverse, and so I don’t know what laws are fixed. I also don’t have a quantum theory of gravity, so I can’t tell you for certain how space comes into existence, but to make the argument that a quantum vacuum that has particles is the same as one that doesn’t have particles is to not understand field theory.

    I’m not sure that anyone is arguing that they’re the same thing–

    Krauss: Well, I read a moronic philosopher who did a review of my book in the New York Times who somehow said that having particles and no particles is the same thing, and it’s not. The quantum state of the universe can change and it’s dynamical. He didn’t understand that when you apply quantum field theory to a dynamic universe, things change and you can go from one kind of vacuum to another. When you go from no particles to particles, it means something.

    I think the problem for me, coming at this as a layperson, is that when you’re talking about the explanatory power of science, for every stage where you have a “something,”—even if it’s just a wisp of something, or even just a set of laws—there has to be a further question about the origins of that “something.” And so when I read the title of your book, I read it as “questions about origins are over.”

    Krauss: Well, if that hook gets you into the book that’s great. But in all seriousness, I never make that claim. In fact, in the preface I tried to be really clear that you can keep asking “Why?” forever. At some level there might be ultimate questions that we can’t answer, but if we can answer the “How?” questions, we should, because those are the questions that matter. And it may just be an infinite set of questions, but what I point out at the end of the book is that the multiverse may resolve all of those questions. From Aristotle’s prime mover to the Catholic Church’s first cause, we’re always driven to the idea of something eternal. If the multiverse really exists, then you could have an infinite object—infinite in time and space as opposed to our universe, which is finite. That may beg the question as to where the multiverse came from, but if it’s infinite, it’s infinite. You might not be able to answer that final question, and I try to be honest about that in the book. But if you can show how a set of physical mechanisms can bring about our universe, that itself is an amazing thing and it’s worth celebrating. I don’t ever claim to resolve that infinite regress of why-why-why-why-why; as far as I’m concerned it’s turtles all the way down. The multiverse could explain it by being eternal, in the same way that God explains it by being eternal, but there’s a huge difference: the multiverse is well motivated and God is just an invention of lazy minds.

    In the past you’ve spoken quite eloquently about the Multiverse, this idea that our universe might be one of many universes, perhaps an infinite number. In your view does theoretical physics give a convincing account of how such a structure could come to exist?

    Krauss: In certain ways, yes—in other ways, no. There are a variety of multiverses that people in physics talk about. The most convincing one derives from something called inflation, which we’re pretty certain happened because it produces effects that agree with almost everything we can observe. From what we know about particle physics, it seems quite likely that the universe underwent a period of exponential expansion early on. But inflation, insofar as we understand it, never ends—it only ends in certain regions and then those regions become a universe like ours. You can show that in an inflationary universe, you produce a multiverse, you produce an infinite number of causally separated universes over time, and the laws of physics are different in each one. There’s a real mechanism where you can calculate it.

    And all of that comes, theoretically, from a very small region of space that becomes infinitely large over time. There’s a calculable multiverse; it’s almost required for inflation—it’s very hard to get around it. All the evidence suggests that our universe resulted from a period of inflation, and it’s strongly suggestive that well beyond our horizon there are other universes that are being created out of inflation, and that most of the multiverse is still expanding exponentially.

    Is there an empirical frontier for this? How do we observe a multiverse?

    Krauss: Right. How do you tell that there’s a multiverse if the rest of the universes are outside your causal horizon? It sounds like philosophy. At best. But imagine that we had a fundamental particle theory that explained why there are three generations of fundamental particles, and why the proton is two thousand times heavier than the electron, and why there are four forces of nature, etc. And it also predicted a period of inflation in the early universe, and it predicts everything that we see and you can follow it through the entire evolution of the early universe to see how we got here. Such a theory might, in addition to predicting everything we see, also predict a host of universes that we don’t see. If we had such a theory, the accurate predictions it makes about what we can see would also make its predictions about what we can’t see extremely likely. And so I could see empirical evidence internal to this universe validating the existence of a multiverse, even if we could never see it directly.

    You have said that your book is meant to describe “the remarkable revolutions that have taken place in our understanding of the universe over the past 50 years–revolutions that should be celebrated as the pinnacle of our intellectual experience.” I think that’s a worthy project and, like you, I find it lamentable that some of physics’ most extraordinary discoveries have yet to fully penetrate our culture. But might it be possible to communicate the beauty of those discoveries without tacking on an assault on previous belief systems, especially when those belief systems aren’t necessarily scientific?

    Krauss: Well, yes. I’m sympathetic to your point in one sense, and I’ve had this debate with Richard Dawkins; I’ve often said to him that if you want people to listen to you, the best way is not to go up to them and say, “You’re stupid.” Somehow it doesn’t get through.

    It’s a fine line and it’s hard to tell where to fall on this one. What drove me to write this book was this discovery that the nature of “nothing” had changed, that we’ve discovered that “nothing” is almost everything and that it has properties. That to me is an amazing discovery. So how do I frame that? I frame it in terms of this question about something coming from nothing. And part of that is a reaction to these really pompous theologians who say, “out of nothing, nothing comes,” because those are just empty words. I think at some point you need to provoke people. Science is meant to make people uncomfortable. And whether I went too far on one side or another of that line is an interesting question, but I suspect that if I can get people to be upset about that issue, then on some level I’ve raised awareness of it.

    The unfortunate aspect of it is, and I’ve come to realize this recently, is that some people feel they don’t even need to read the book, because they think I’ve missed the point of the fundamental theological question. But I suspect that those people weren’t open to it anyway. I think Steven Weinberg said it best when he said that science doesn’t make it impossible to believe in God, it just makes it possible to not believe in God. That’s a profoundly important point, and to the extent that cosmology is bringing us to a place where we can address those very questions, it’s undoubtedly going to make people uncomfortable. It was a judgment call on my part and I can’t go back on it, so it’s hard to know.

    You’ve developed this wonderful ability to translate difficult scientific concepts into language that can enlighten, and even inspire a layperson. There are people in faith communities who are genuinely curious about physics and cosmology, and your book might be just the thing to quench and multiply that curiosity. But I worry that by framing these discoveries in language that is in some sense borrowed from the culture war, that you run the risk of shrinking the potential audience for them—and that could ultimately be a disservice to the ideas.

    Krauss: Ultimately, it might be. I’ve gone to these fundamentalist colleges and I’ve gone to Fox News and it’s interesting, the biggest impact I’ve ever had is when I said, “you don’t have to be an atheist to believe in evolution.” I’ve had young kids come up to me and say that affected them deeply. So yes it’s nice to point that out, but I actually think that if you read my book I never say that we know all the answers, I say that it’s pompous to say that we can’t know the answers. And so yeah I think that maybe there will be some people who are craving this stuff and who won’t pick up my book because of the way I’ve framed it, but at the same time I do think that people need to be aware that they can be brave enough to ask the question “Is it possible to understand the universe without God?” And so you’re right that I’m going to lose some people, but I’m hoping that at the same time I’ll gain some people who are going to be brave enough to come out of the closet and ask that question. And that’s what amazes me, that nowadays when you simply ask the question you’re told that you’re offending people.

    But let me bring that back full circle. You opened this conversation talking about seduction. You’re not giving an account of seduction right now.

    Krauss: That’s true, but let me take it back full circle to Hitchens. What Christopher had was charm, humor, wit and culture as weapons against nonsense, and in my own small way what I try and do in my books is exactly that. I try and infuse them with humor and culture and that’s the seduction part. And in this case the seduction might be causing people to ask, “How can he say that? How can he have the temerity to suggest that it’s possible to get something from nothing? Let me see what’s wrong with these arguments.” If I’d just titled the book “A Marvelous Universe,” not as many people would have been attracted to it. But it’s hard to know. I’m acutely aware of this seduction problem, and my hope is that what I can do is get people to listen long enough to where I can show some of what’s going on, and at the same time make them laugh.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    • makingsenseofcomplications 9:26 am on June 27, 2016 Permalink | Reply

      I haven’t read this yet, but believe the three address different facets of the (necessarily) human experience. I prefer the scientific realm, but religion and philosophy are unmistakable elements of the human experience, however illogical or off-base they may be.


  • richardmitnick 2:57 pm on June 23, 2016 Permalink | Reply
    Tags: , , Physics   

    From Carnegie: “Probing giant planets’ dark hydrogen” 

    Carnegie Institution for Science
    Carnegie Institution for Science

    June 23, 2016
    Alexander Goncharov

    An illustration of the layer of dark hydrogen the team’s lab mimicry indicates would be found beneath the surface of gas giant planets like Jupiter, courtesy of Stewart McWilliams.

    Hydrogen is the most-abundant element in the universe. It’s also the simplest—sporting only a single electron in each atom. But that simplicity is deceptive, because there is still so much we have to learn about hydrogen.

    One of the biggest unknowns is its transformation under the extreme pressures and temperatures found in the interiors of giant planets, where it is squeezed until it becomes liquid metal, capable of conducting electricity. New work published in Physical Review Letters by Carnegie’s Alexander Goncharov and University of Edinburgh’s Stewart McWilliams measures the conditions under which hydrogen undergoes this transition in the lab and finds an intermediate state between gas and metal, which they’re calling “dark hydrogen.”

    On the surface of giant planets like Jupiter, hydrogen is a gas. But between this gaseous surface and the liquid metal hydrogen in the planet’s core lies a layer of dark hydrogen, according to findings gleaned from the team’s lab mimicry.

    Using a laser-heated diamond anvil cell to create the conditions likely to be found in gas giant planetary interiors, the team probed the physics of hydrogen under a range of pressures from 10,000 to 1.5 million times normal atmospheric pressure and up to 10,000 degrees Fahrenheit.

    They discovered this unexpected intermediate phase, which does not reflect or transmit visible light, but does transmit infrared radiation, or heat.

    “This observation would explain how heat can easily escape from gas giant planets like Saturn,” explained Goncharov.

    They also found that this intermediate dark hydrogen is somewhat metallic, meaning it can conduct an electric current, albeit poorly. This means that it could play a role in the process by which churning metallic hydrogen in gas giant planetary cores produces a magnetic field around these bodies, in the same way that the motion of liquid iron in Earth’s core created and sustains our own magnetic field.

    “This dark hydrogen layer was unexpected and inconsistent with what modeling research had led us to believe about the change from hydrogen gas to metallic hydrogen inside of celestial objects,” Goncharov added.

    The team also included Carnegie’s Allen Dalton and Howard University’s Mohammad Mahmood.

    This work was supported by the NSF Major Research Instrumentation program, the Army Research Office, the Carnegie Institution for Science, the Deep Carbon Observatory Instrumentation grant, the British Council Researcher Links programme, the DOE NNSA Carnegie/DOE Alliance Center, and the DOE EFRC for Energy Frontier Research in Extreme Environments.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Carnegie Institution of Washington Bldg

    Andrew Carnegie established a unique organization dedicated to scientific discovery “to encourage, in the broadest and most liberal manner, investigation, research, and discovery and the application of knowledge to the improvement of mankind…” The philosophy was and is to devote the institution’s resources to “exceptional” individuals so that they can explore the most intriguing scientific questions in an atmosphere of complete freedom. Carnegie and his trustees realized that flexibility and freedom were essential to the institution’s success and that tradition is the foundation of the institution today as it supports research in the Earth, space, and life sciences.

  • richardmitnick 2:38 pm on June 21, 2016 Permalink | Reply
    Tags: , , Physics, , Twisted light   

    From Science Alert: “Physicists just sent ‘twisted light’ 143 kilometres to set a new world record” 


    Science Alert

    21 JUN 2016

    Zellinger Group

    Sending telescope
    Observatorio del Roque de los Muchachos, La Palma

    Receiving telescope
    Observatorio de El Teide, Tenerife


    Scientists have broken the world record for optical data transfer, beaming what’s called ‘twisted light’ over a distance of 143 kilometres (almost 90 miles).

    If you’re scratching your head over what twisted light is, it’s actually exactly what it sounds like: a beam of light where the particles aren’t all travelling forward in a linear block, but are twisting as they go, like a corkscrew through the air.

    The new milestone represents a 50-fold improvement on the previous record, according to researchers from the University of Vienna in Austria, and while they’re not ready for real-world applications yet, these twisted beams of light could one day be used to send large volumes of data at blisteringly high speeds.

    Also called an optical vortex, twisted light could improve current fibre optic technology because it allows more data to be sent simultaneously – separate channels of information could be broadcast at the same time, using different amounts of twist.

    Scientists are still figuring out the practicalities of how such a system would work, because right now, one problem is beaming an optical vortex without the light (and therefore the data) being scrambled along the way.

    Having been trained using data from beams distorted by turbulence, their computer-powered neural network was able to successfully decode messages about 80 percent of the time.

    That figure – and the overall distance – should get higher over time, as the technology and methods are further refined. The team used a green laser beam at the sending station in La Palmer, with the resulting magnified light collected on the wall of the Observatorio del Teide in Tenerife.

    The experiment took 10 days in total, which means there’s clearly room for improvement, seeing as that’s about as fast as a smoke signal. Still, in science, you’ve gotta start somewhere.

    In the future, this kind of technology could eventually allow for high-speed data transmission between satellites and Earth’s surface, the scientists say.

    “We don’t consider this method as real communication, but merely the demonstration of the transmission quality of modes,” write the researchers. “However, the application of state-of-the-art adaptive optics such as those used in simple and efficient intensity-based methods could further improve the link quality.”

    A paper detailing the research has been published on pre-print website arXiv.org, is currently awaiting peer-review.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

  • richardmitnick 11:45 am on June 21, 2016 Permalink | Reply
    Tags: , Four fundamental forces of nature, , Physics,   

    From Symmetry: “All four one and one for all” 

    Symmetry Mag

    Matthew R. Francis

    A theory of everything would unite the four forces of nature, but is such a thing possible?


    Over the centuries, physicists have made giant strides in understanding and predicting the physical world by connecting phenomena that look very different on the surface.

    One of the great success stories in physics is the unification of electricity and magnetism into the electromagnetic force in the 19th century. Experiments showed that electrical currents could deflect magnetic compass needles and that moving magnets could produce currents.

    Then physicists linked another force, the weak force, with that electromagnetic force, forming a theory of electroweak interactions. Some physicists think the logical next step is merging all four fundamental forces—gravity, electromagnetism, the weak force and the strong force—into a single mathematical framework: a theory of everything.

    Those four fundamental forces of nature are radically different in strength and behavior. And while reality has cooperated with the human habit of finding patterns so far, creating a theory of everything is perhaps the most difficult endeavor in physics.

    “On some level we don’t necessarily have to expect that [a theory of everything] exists,” says Cynthia Keeler, a string theorist at the Niels Bohr Institute in Denmark. “I have a little optimism about it because historically, we have been able to make various unifications. None of those had to be true.”

    Despite the difficulty, the potential rewards of unification are great enough to keep physicists searching. Along the way, they’ve discovered new things they wouldn’t have learned had it not been for the quest to find a theory of everything.

    CERN/ATLAS http://atlasexperiment.org

    United we hope to stand

    No one has yet crafted a complete theory of everything.

    It’s hard to unify all of the forces when you can’t even get all of them to work at the same scale. Gravity in particular tends to be a tricky force, and no one has come up with a way of describing the force at the smallest (quantum) level.

    Physicists such as Albert Einstein thought seriously about whether gravity could be unified with the electromagnetic force. After all, general relativity had shown that electric and magnetic fields produce gravity and that gravity should also make electromagnetic waves, or light. But combining gravity and electromagnetism, a mission called unified field theory, turned out to be far more complicated than making the electromagnetic theory work. This was partly because there was (and is) no good theory of quantum gravity, but also because physicists needed to incorporate the strong and weak forces.

    A different idea, quantum field theory, combines Einstein’s special theory of relativity with quantum mechanics to explain the behavior of particles, but it fails horribly for gravity. That’s largely because anything with energy (or mass, thanks to relativity) creates a gravitational attraction—including gravity itself. To oversimplify somewhat, the gravitational interaction between two particles has a certain amount of energy, which produces an additional gravitational interaction with its own energy, and so on, spiraling to higher energies with each extra piece.

    “One of the first things you learn about quantum gravity is that quantum field theory probably isn’t the answer,” says Robert McNees, a physicist at Loyola University Chicago. “Quantum gravity is hard because we have to come up with something new.”


    An evolution of theories

    The best-known candidate for a theory of everything is string theory, in which the fundamental objects are not particles but strings that stretch out in one dimension.

    Calabi yau.jpg

    Strings were proposed in the 1970s to try to explain the strong force. This first string theory proved to be unnecessary, but physicists realized it could be joined to the another theory called Kaluza-Klein theory as a possible explanation of quantum gravity.

    String theory expresses quantum gravity in two dimensions rather than the four, bypassing all the problems of the quantum field theory approach but introducing other complications, namely an extra six dimensions that must be curled up on a scale too small to detect.

    Unfortunately, string theory has yet to reproduce the well-tested predictions of the Standard Model.

    Another well-known idea is the sci-fi-sounding “loop quantum gravity,” in which space-time on the smallest scales is made of tiny loops in a flexible mesh that produces gravity as we know it.

    The idea that space-time is made up of smaller objects, just as matter is made of particles, is not unique to the theory. There are many others with equally Jabberwockian names: twistors, causal set theory, quantum graphity and so on. Granular space-time might even explain why our universe has four dimensions rather than some other number.

    Loop quantum gravity’s trouble is that it can’t replicate gravity at large scales, such as the size of the solar system, as described by general relativity.

    None of these theories has yet succeeded in producing a theory of everything, in part because it’s so hard to test them.

    “Quantum gravity is expected to kick in only at energies higher than anything that we can currently produce in a lab,” says Lisa Glaser, who works on causal set quantum gravity at the University of Nottingham. “The hope in many theories is now to predict cumulative effects,” such as unexpected black hole behavior during collisions like the ones detected recently by LIGO.

    Today, many of the theories first proposed as theories of everything have moved beyond unifying the forces. For example, much of the current research in string theory is potentially important for understanding the hot soup of particles known as the quark-gluon plasma, along with the complex behavior of electrons in very cold materials like superconductors—something seemingly as far removed from quantum gravity as could be.

    “On a day-to-day basis, I may not be doing a calculation that has anything directly to do with string theory,” Keeler says. “But it’s all about these ideas that came from string theory.”

    Finding a theory of everything is unlikely to change the way most of us go about our business, even if our business is science. That’s the normal way of things: Chemists and electricians don’t need to use quantum electrodynamics, even though that theory underlies their work. But finding such a theory could change the way we think of the universe on a fundamental level.

    Even a successful theory of everything is unlikely to be a final theory. If we’ve learned anything from 150 years of unification, it’s that each step toward bringing theories together uncovers something new to learn.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 8:53 am on June 18, 2016 Permalink | Reply
    Tags: , Cheerios Effect, , Physics   

    From GIZMODO: “Physicists Turn the Cheerios Effect Inside Out” 

    GIZMODO bloc


    Jennifer Ouellette

    Image: Vlue/Shutterstock

    We’ve all noticed how those last few Cheerios in the cereal bowl seem to cluster together in the center and along the edges. It’s called the “Cheerios effect.” Now an international team of physicists has discovered a reverse Cheerios effect. They described their results in a new paper in the Proceedings of the National Academy of Sciences.

    The Cheerios effect may not be an especially exotic phenomenon—we also see it in pollen floating atop a pond, and the foamy heads of beer—but the actual physical mechanisms at work weren’t clearly outlined until a 2005 paper in the American Journal of Physics. The culprits: buoyancy, surface tension, and something called the “meniscus effect.”

    Buoyancy is what determines whether something will sink or float, while surface tension is a property arising from water molecules pulling on one another in a dance of mutual attraction. The liquids essentially cling to each other so tightly that they form a kind of skin over the top of the liquid.

    The meniscus effect is what happens when you place a single Cheerio in a bowl of milk. Its mass will form a dent in the milk’s surface. Place a second Cheerio in the bowl, and it will do the same. If the two Cheerios are close enough together, they will drift toward each other. It’s a microcosm of general relativity, whereby the mass of the Sun warps the fabric of spacetime, pulling the planets into orbit around it. Place yet another Cheerio near the edge of the bowl, and it will follow the curve of that meniscus, looking for all the world like it’s clinging to the edge of the bowl.

    And now there’s a way to get an inverted Cheerios effect, by swapping the roles of Cheerio and liquid. This latest work explores what happens when you have liquid drops resting on a soft solid surface. Even better, the physicists discovered they could actually control how those liquid drops clustered together across that surface, simply by making the surfaces softer or harder, or changing the thickness of that soft layer.

    “The droplets deform the surface on which they live, and due to this deformation, they interact—somewhat reminiscent of general relativity, from which we know that galaxies or black holes interact by deforming space around them,” co-author Stefan Karpitschka, now at Stanford University, said in a statement.. “What is remarkable about our case though is the fact that the direction of the interaction can be tuned by the medium, without modifying the particles themselves.”

    The original Cheerios effect led to advanced materials and insight into how galaxies collapse via gravity. Its inverse also has lots of potential applications, according to co-author Lorenzo Botto of Queen Mary University of London. “[T]he physical phenomena we have highlighted in this paper suggest ways to design surfaces that prevent fogging or control heat transfer,” he said. This would make it possible to “create car windows that are always transparent despite high humidity or surfaces that improve heat management in conditioners or boilers.”

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    “We come from the future.”

    GIZMOGO pictorial

  • richardmitnick 2:55 pm on June 17, 2016 Permalink | Reply
    Tags: , , E.O. Lawrence, Physics,   

    From SURF: A giant among men 

    SURF logo
    Sanford Underground levels

    Sanford Underground Research facility

    March 23, 2015 [Just appeared in social media]
    Constance Walter

    Ernest Orlando Lawrence sitting on a hillside above the 184-inch cyclotron, circa 1950s. Photo courtesy of Berkeley Lab

    South Dakota native won Nobel Prize 75 years ago

    In 1928, 27-year-old Ernest Lawrence left the security of Yale to become an assistant professor in the University of California, Berkeley’s fledgling physics department. Friends predicted he would “quickly go to seed in the unscientific climate of the west,” Luis Alvarez wrote in a biography of Lawrence.

    They couldn’t have been more wrong. Just 11 years later, Lawrence received the Nobel Prize in Physics for his invention of the cyclotron, the world’s first particle accelerator.

    Lawrence grew up in Canton, S.D., where his father served as superintendent of schools. After graduating from high school, Lawrence attended college at St. Olaf’s in Northfield, Minn. but returned to his native state one year later to finish his bachelor’s degree. He went on to receive his Ph.D. from Yale in 1925.

    From early childhood, Lawrence demonstrated scientific ingenuity and daring, wrote Alvarez, a Nobel Laureate. Lawrence and his childhood friend Merle Tuve built and flew gliders and constructed a very early short-wave radio transmitting station. They “carried the friendly rivalry of their boyhood days into the formative stages of American nuclear physics, and all nuclear physicists have benefitted greatly from the results,” Alvarez wrote.

    This year marks 75 years since Lawrence accepted the Nobel. His work in the field of nuclear science runs deep—all the way back to South Dakota and Sanford Lab. Lawrence Livermore National Laboratory (LLNL) and Lawrence Berkeley National Laboratory (LBNL) are named for him and both are connected to the Large Underground Xenon (LUX) experiment. “The particle accelerator principles developed by Lawrence will be reflected in LBNF and used to study neutrinos,” said Jaret Heise, Director of Science at Sanford Lab.

    LLNL Plate

    LBL Big

    LUX Xenon experiment at SURF
    LUX Xenon experiment at SURF

    Lawrence called his first cyclotron, which had a 5-inch accelerating chamber, his proton merry-go-round. Lynn Yarris, a writer for LBNL, described it as “a pie-shaped concoction of glass, sealing wax, and bronze. A kitchen chair and a wire-coiled clothes tree were also enlisted to make the device work.” Despite it’s crude appearance, Lawrence proved that accelerating particles to very high velocities was the best way to smash open atomic nuclei.

    Lawrence would go on to develop far more sophisticated cyclotrons that required more space. In 1931, Berkeley turned over its Civil Engineering Testing Lab to Lawrence and renamed it the Radiation Laboratory. It housed the 27-inch, 36-inch, and 60-inch cyclotrons. In 1946, a new facility was built for his 184-inch cyclotron.

    During World War II, Lawrence worked on the Manhattan Project, which produced the first atomic bombs. Later, Lawrence was part of an effort that sought an international agreement to suspend atomic bomb testing.

    On February 29, 1940, Ernest Lawrence accepted the Nobel for his invention in a ceremony held at UC Berkeley—the war made international travel nearly impossible. In his acceptance speech, he expressed “a profound feeling of gratitude and appreciation for this great honor, which I share with all those outside who have contributed to make our work possible and above all with my valued colleagues and co-workers both past and present.”

    Lawrence died on August 27, 1958, of a chronic illness. He was 57 years old. Alvarez, his friend and colleague, wrote, “For those who had the good fortune to be close to him both personally and scientifically he will always seem a giant among men. He will always be remembered as the inventor of the cyclotron, but more importantly, he should be remembered as the inventor of the modern way of doing science.”

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon

    Stem Education Coalition

    About us.
    The Sanford Underground Research Facility in Lead, South Dakota, advances our understanding of the universe by providing laboratory space deep underground, where sensitive physics experiments can be shielded from cosmic radiation. Researchers at the Sanford Lab explore some of the most challenging questions facing 21st century physics, such as the origin of matter, the nature of dark matter and the properties of neutrinos. The facility also hosts experiments in other disciplines—including geology, biology and engineering.

    The Sanford Lab is located at the former Homestake gold mine, which was a physics landmark long before being converted into a dedicated science facility. Nuclear chemist Ray Davis earned a share of the Nobel Prize for Physics in 2002 for a solar neutrino experiment he installed 4,850 feet underground in the mine.

    Homestake closed in 2003, but the company donated the property to South Dakota in 2006 for use as an underground laboratory. That same year, philanthropist T. Denny Sanford donated $70 million to the project. The South Dakota Legislature also created the South Dakota Science and Technology Authority to operate the lab. The state Legislature has committed more than $40 million in state funds to the project, and South Dakota also obtained a $10 million Community Development Block Grant to help rehabilitate the facility.

    In 2007, after the National Science Foundation named Homestake as the preferred site for a proposed national Deep Underground Science and Engineering Laboratory (DUSEL), the South Dakota Science and Technology Authority (SDSTA) began reopening the former gold mine.

    In December 2010, the National Science Board decided not to fund further design of DUSEL. However, in 2011 the Department of Energy, through the Lawrence Berkeley National Laboratory, agreed to support ongoing science operations at Sanford Lab, while investigating how to use the underground research facility for other longer-term experiments. The SDSTA, which owns Sanford Lab, continues to operate the facility under that agreement with Berkeley Lab.

    The first two major physics experiments at the Sanford Lab are 4,850 feet underground in an area called the Davis Campus, named for the late Ray Davis. The Large Underground Xenon (LUX) experiment is housed in the same cavern excavated for Ray Davis’s experiment in the 1960s.
    LUX/Dark matter experiment at SURFLUX/Dark matter experiment at SURF

    In October 2013, after an initial run of 80 days, LUX was determined to be the most sensitive detector yet to search for dark matter—a mysterious, yet-to-be-detected substance thought to be the most prevalent matter in the universe. The Majorana Demonstrator experiment, also on the 4850 Level, is searching for a rare phenomenon called “neutrinoless double-beta decay” that could reveal whether subatomic particles called neutrinos can be their own antiparticle. Detection of neutrinoless double-beta decay could help determine why matter prevailed over antimatter. The Majorana Demonstrator experiment is adjacent to the original Davis cavern.

    Another major experiment, the Long Baseline Neutrino Experiment (LBNE)—a collaboration with Fermi National Accelerator Laboratory (Fermilab) and Sanford Lab, is in the preliminary design stages. The project got a major boost last year when Congress approved and the president signed an Omnibus Appropriations bill that will fund LBNE operations through FY 2014. Called the “next frontier of particle physics,” LBNE will follow neutrinos as they travel 800 miles through the earth, from FermiLab in Batavia, Ill., to Sanford Lab.

    Fermilab LBNE

  • richardmitnick 11:24 am on June 17, 2016 Permalink | Reply
    Tags: , , , Physics   

    From CERN: “First beam enters unique AWAKE experiment” 

    Cern New Bloc

    Cern New Particle Event

    CERN New Masthead


    17 Jun 2016
    Harriet Kim Jarlett

    CERN Awake schematic
    CERN Awake schematic

    The team in the control room on the 16 June 2016 as the first beam of particles are sent through the proton beam line to the AWAKE experiment (Image: Ans Pardons/CERN)

    For the first time a beam of particles has been sent through the pioneering AWAKE experiment signaling the next stage of its commissioning.

    This is a test beam, meaning its purpose is to see whether all the parts of the beam line to the experiment are working correctly, and that the magnets are aligning the beam in the correct way.

    AWAKE (the Advanced Proton Driven Plasma Wakefield Acceleration Experiment) will be the first accelerator of its kind in the world. It is currently under construction, but hopes to test the concept that plasma wakefields driven by a proton beam could accelerate charged particles.

    The proton beam has to travel along around 800 m of proton beam line through the 10 m plasma cell, which at the moment is just an empty tube as the plasma is not filled yet, then downstream are several detectors.

    “What was really nice is that when we first sent the beam down the proton line to the experiment area, it immediately hit the last detector, verifying our calculations and installation. We can now move onto the next stage of commissioning. There is a strong and wonderful team behind this success,” explains Edda Gschwendtner, the project leader.

    The beam comes from CERN’s Super Proton Synchrotron (SPS), which just celebrated its fortieth birthday.

    CERN  Super Proton Synchrotron
    CERN Super Proton Synchrotron

    “Now we have to do the real work, checking all the details, but it’s great that the very first test showed everything is very consistent. Yes, now we have the beam but we still have to measure and calibrate everything, like the beam instrumentation along the beam line,” says Edda.

    AWAKE hopes to start collecting physics data by the end of the year. Next the team will finalise installation of the experiment, the laser and the full plasma cell.

    If it works this technology will mean linear colliders in the future could be much shorter, and even table-top accelerators could be possible.

    ILC schematic
    ILC schematic

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Meet CERN in a variety of places:

    Cern Courier




    CERN CMS New

    CERN LHCb New II


    CERN LHC Map
    CERN LHC Grand Tunnel

    CERN LHC particles

    Quantum Diaries

  • richardmitnick 10:10 am on June 16, 2016 Permalink | Reply
    Tags: , , Light and matter mixed in a tiny golden trap, Physics   

    From ICL: “Light and matter mixed in a tiny golden trap” 

    Imperial College London
    Imperial College London

    13 June 2016
    Hayley Dunning

    R Chikkaraddy/J Baumberg
    Scientists have mixed a molecule with light between gold particles, creating a new way to manipulate the physical and chemical properties of matter.

    Light and matter are usually separate and have distinct properties. However, molecules of matter can emit particles of light called photons. Normally, emitted photons leave the molecule and the two do not mix again.

    Now, scientists have trapped a single molecule in such a tiny space that when it emits a photon, the photon cannot escape. This produces an oscillation of energy between the molecule and the photon, creating a mixing of the properties of matter and light.

    This unusual interaction of a molecule with light will provide new ways to manipulate the physical and chemical properties of matter, and could be used to process quantum information, aid in the understanding of complex processes at work in photosynthesis, or even manipulate the chemical bonds between atoms.

    The mixing – called ‘strong coupling’ – was achieved at the University of Cambridge following theoretical simulations by scientists from Imperial College London and Kings College London. The results of the experiment are published today in the journal Nature.

    Nature and theory

    To trap the photon, researchers created a ‘nanopore’ – an extremely small cavity of only a billionth of a metre (one nanometre) wide. The cavity is formed between a tiny sphere of gold and a gold film, which creates a mirror image of the sphere. In between the sphere and its mirror image, a dye molecule is caught. This molecule emits the photon that becomes trapped.

    Image: R Chikkaraddy/J Baumberg

    “The cavity is so small that light doesn’t have a choice but to come together with matter,” said Professor Ortwin Hess from Imperial’s Department of Physics, who led in the theory of how to achieve strong coupling and how to interpret the result.

    Photons are packages of light that can behave both like particles and like waves, in a way that is described as ‘quantum’. “The experiment is a test that light is quantum in nature and indeed it showed the quantum effects we predicted,” said Professor Hess. “This is a remarkable crossing of theory and experiment. It’s amazing how much nature behaves like the theory.”

    Whole new experiments

    Strong coupling has been achieved before, but it has previously required extreme cooling. This is the first time strong coupling with a single molecule has been achieved at room temperature, making the process “chemically easy to access” according to Professor Hess.

    “We can now do a whole range of experiments on matter and light that would have been costly and difficult before,” said Professor Hess. “We could use light to change chemical structures, molecule by molecule.

    “It could also be useful in quantum technologies. Light carries quantum information, and we could use this strong coupling to copy the information over to matter and back.”

    Professor Hess and his research team at Imperial are exploring the theory of such strong coupling interactions for use in creating the smallest ever lasers by stopping light in in its tracks.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Imperial College London

    Imperial College London is a science-based university with an international reputation for excellence in teaching and research. Consistently rated amongst the world’s best universities, Imperial is committed to developing the next generation of researchers, scientists and academics through collaboration across disciplines. Located in the heart of London, Imperial is a multidisciplinary space for education, research, translation and commercialisation, harnessing science and innovation to tackle global challenges.

  • richardmitnick 11:51 am on June 15, 2016 Permalink | Reply
    Tags: , , , BNL sPHENIX, , , , Physics   

    From BNL: “Introducing…sPHENIX!” 

    Brookhaven Lab

    June 15, 2016
    Karen McNulty Walsh

    Members of the new sPHENIX collaboration at a meeting held at Brookhaven Lab in May 2016, with co-spokespersons Dave Morrison (green T-shirt, jeans) and Gunther Roland (blue shirt, black jeans) front and center.

    From the very beginning, there were hints that particle collisions at the Relativistic Heavy Ion Collider (RHIC) were producing something unusual. This U.S. Department of Energy (DOE) Office of Science User Facility at Brookhaven National Laboratory was designed to recreate the incredibly hot and dense conditions of matter in the early universe by colliding atomic nuclei at high enough energies to “melt” their constituent protons and neutrons. The collisions would “free” those particles’ inner building blocks—quarks and gluons—so nuclear physicists could study their behavior unbound from ordinary matter.

    Results from RHIC show that these particle smashups have indeed created a superhot primordial soup called “quark-gluon plasma” (QGP)—but one in which the quarks and gluons, though liberated from their protons and neutrons, continue to interact strongly. These strong interactions make the plasma flow like a nearly “perfect” liquid.

    RHIC’s discovery of the perfect liquid set off a decade-long and very successful effort to characterize its remarkable properties—both at RHIC and at Europe’s Large Hadron Collider (LHC), where physicists conduct complementary studies of quark-gluon plasma for a few weeks of each year. But understanding exactly how the QGP’s perfect fluidity and other collective properties emerge from its point-like constituent particles remains a compelling mystery.

    To address that mystery, a group of nuclear physicists has formed a new scientific collaboration that will expand on discoveries made by RHIC’s existing STAR and PHENIX research groups. This new collaboration, made up of veterans of the field and researchers just beginning their careers, has precise ideas about the measurements its members would like to make—and hopes of upgrading the PHENIX detector to make those measurements at RHIC.

    “What remains to be done is to understand how the QGP’s properties arise or emerge from the underlying quark and gluon interactions,” said Massachusetts Institute of Technology physicist Gunther Roland, a longtime RHIC and LHC collaborator and now a co-spokesperson for the new collaboration..

    Brookhaven physicist Dave Morrison, the other co-spokesperson, agrees: “On the one hand we have a very successful theory that describes the quarks and gluons as free point-like particles. On the other hand, we have a whole set of measurements that describe the collective properties of the QGP. What we’d like to do is connect the two—the microscopic to the not-so-microscopic.”

    For now, the collaboration goes by the name sPHENIX: “s” for its focus on the strongly interacting particles and PHENIX for the anticipated use of key detector components and that experiment’s location in the RHIC ring once the existing PHENIX systems complete their data-taking lifetime at the end of this year’s run. But the collaboration leaders emphasize that there’s no need for members to be previously affiliated with PHENIX—or indeed with prior research at RHIC.

    “This is a new collaboration, and, if we get the go-ahead for this upgrade, this detector will have brand new capabilities,” Morrison said.

    A schematic of the proposed sPHENIX detector, showing several key components: outer and inner hadronic calorimeters (HCal), electromagnetic (EM) calorimeter, tracking systems, and coils of the superconducting solenoid magnet

    BNL/RHIC Phenix

    BNL/ Phenix
    BNL/ Phenix another view

    Tracking probes from within the plasma

    Figuring out how the QGP’s properties emerge from its smallest particles requires a detector that can make more—and more precise—measurements of what’s going on in the plasma at different length scales.

    “Think about looking at a pond that behaves like a liquid,” Morrison explained. “You might see waves and flowing water. If you had a microscope that could dial down, at some point you would see water molecules—the particles that make up the water. If you know a lot about those particles and how they behave, you can try to understand how the properties of the pond arise from the properties of the molecules. That’s what we’d like to do with the QGP.”

    Particle detectors are the microscopes nuclear physicists use to dive down into the details of subatomic matter. But instead of shining visible light, electrons, or x-rays on the sample, particle detectors pick up signals from particles created within the collisions. Measuring how these particles move through and lose energy by interacting with the plasma will reveal information about the QGP at scales between the level of individual quarks and the long-scale collective behavior.

    “There has to be an evolution from the short-wavelength behavior to the long-wavelength behavior, and we want to probe that transition,” Roland said.

    Fast detector for precision measurements

    One set of particles sPHENIX physicists are interested in tracking are upsilons—each made of two heavy quarks bound together. Each different bound state has a different mass. The sPHENIX scientists want to understand how upsilons with different masses form and disassociate and otherwise interact with the plasma.

    They’re also interested in analyzing collimated streams of particles called jets—created as the energy of individual fast-moving quarks and gluons is transformed into a cascade of new particles. Measuring how much energy is lost by higher- and lower-energy jets will convey information about both the individual particle scale deep within the plasma and its long-range characteristics.

    “The higher the momentum, the more rarely it is produced. So you need a very fast detector that can capture a lot of collisions to increase the chances of spotting these important events,” Roland said.

    By removing outdated components from PHENIX and replacing them with new, custom-designed systems, the sPHENIX collaboration would transform that experiment into a “new” state-of-the-art detector that can capture as many as 15,000 events per second—a significant increase over STAR’s current capture rate of 2,000 events per second, or PHENIX’s 5,000—with all the components needed to differentiate among the three mass states of upsilons and tease apart the full energy scale of jets.

    “This transformed detector would be suited to record a huge fraction of what RHIC can produce,” Morrison said.

    Testing essential detector components

    Physicists and engineers at Brookhaven and elsewhere have already begun building prototypes and testing components that could be used to achieve the anticipated transformation. And this endeavor is attracting a new generation of physicists eager to get in on the ground floor of a new experiment.

    “I worked on PHENIX as grad student at Stony Brook University. Then, as a postdoc at Yale, I worked on the ALICE experiment at the LHC,” said Megan Connors, a RIKEN-BNL Research Center Fellow at Brookhaven Lab who will begin teaching and forming her own research group at Georgia State University next year. “When I came on the scene, both colliders were already up and running. So this is a chance to be involved from the start—to see how these experiments come to life, to be part of the formation of the collaboration and get involved in building the hardware in addition to analyzing the data.”

    Megan Connors and Anne Sickles checking out calorimeter components at Brookhaven Lab.

    The piece of hardware that currently has her attention is a prototype “calorimeter” that would track and reconstruct the sprays of particles that make up jets, which recently underwent extensive testing at Fermi National Accelerator Laboratory.

    “A typical jet may contain 10 or 15 particles, but you need to tease those out from the hundreds of particles coming out of a heavy ion collision event,” Connors said. “And you need to capture all the particles to be able to reconstruct the jet and see how much energy it loses as it travels through the plasma.”

    You also need to know how much energy the jet had to start with. Most of the time jets are formed in back-to-back pairs. Both jets lose energy in the plasma. However sometimes, instead, a particle of light called a photon gets produced back-to-back with a jet. But unlike the jet particles, the photon shooting off in the opposite direction does not interact with the quarks and gluons in the plasma, so it doesn’t lose any energy.

    “If you have a photon going one way, and a jet going the other way, the jet and the photon had the same starting energy,” explained Anne Sickles, an sPHENIX collaborator from the University of Illinois at Urbana-Champaign who was also involved in the calorimeter design and testing. “So measuring the photon’s energy gives you the starting point. Measuring the particles that make up the jet and subtracting from the photon energy tells you how much energy the jet lost.”

    Using Fermilab’s Test Beam Facility, Sickles and some of her students shot a beam of electrons through portions of an “electromagnetic” calorimeter they designed to track photons and some of the other particles that make up jets. For the initial tests, the electrons—pure electromagnetic particles like photons—served as stand-ins for the photons. The aim of the tests was to be sure all areas of the detector respond in a similar way, and that there’s no variation between pieces built by Sickles and her students in Illinois and pieces constructed by an outside contractor.

    Next, the physicists added components of a “hadronic” calorimeter for tracking hadrons (particles made of more than one quark), which Connors and her team had been working on. They placed the hadron detectors directly behind the electromagnetic calorimeter—just as the two components will be arranged in the actual detector. This outer layer is designed to catch the larger hadron particles that make it through the first layer so physicists can account for the full energy of each jet.

    Building the calorimeter thick enough to “catch” all the particles is one way that the design of sPHENIX benefits from the 16 years of operating RHIC and several years experience at LHC.

    “Before RHIC was built, we didn’t even know how many particles would be produced. We had to build the detectors to cover a wide range of possibilities,” Morrison said. “Now, knowing what the collisions look like and the kinds of particles produced, we can build a detector tailored to do the measurements that are focused on the specific important questions we’d like to answer.”

    Mighty magnet

    Testing is also underway on a 20-ton solenoid magnet acquired from a former physics experiment at DOE’s SLAC National Accelerator Laboratory. This magnet would form the heart of the sPHENIX detector, completely surrounding the collision zone like the cylindrical magnet at the center of RHIC’s STAR detector. Like STAR’s, the sPHENIX magnet would bend the trajectories of charged particles as they emerge from the collisions. But with three times the bending power of STAR, sPHENIX should be able to separate out the signals from the three types of upsilon particles, whose masses differ by only a few percent.

    “Upsilons don’t make it all the way to the magnet,” Morrison explained. “These are heavy particles that decay, often into an electron and an antielectron, which have a lot of energy when they come out. You need a powerful magnetic field to bend these charged particles so you can get a better measurement of their velocity and momentum, and tease out small differences to separate the electrons that come from the different-size upsilons.”

    So far, a team of engineers and physicists in Brookhaven’s Superconducting Magnet Division, Collider-Accelerator Department, and Physics Department has cooled the superconducting magnet down to its near-absolute-zero operating temperature of 4.2 Kelvin and tested it with 100 amperes of current.

    “We needed to test the overall health and integrity of the magnet to make sure all the joints and couplings are in place, in case they got jostled while being transported cross-country,” said lead magnet engineer Piyush Joshi. They also tested systems Joshi designed to shut the magnet down in a controlled manner if the field between the magnet’s two layers of coils ever gets out of balance. “You want to detect any imbalance very quickly so you can extract the energy before it causes any damage to the magnet,” he said. He originally wrote the algorithms for an LHC magnet project, but they proved to be just as useful for the sPHENIX tests.

    With the initial, low-field tests complete, the group will next use steel recycled from another older experiment at Brookhaven to surround the magnet to contain its most powerful field—and ramp it up to a full 4,600 amps.

    Engineers and physicists involved in testing the 20-ton superconducting solenoid expected to form the heart of the sPHENIX upgrade: Kin Yip, Collider-Accelerator Department (CAD); Piyush Joshi, Superconducting Magnet Division (SMD); Richard Meier, CAD cryo group; Brian Van Kuik, CAD main control room operations coordinator; Ray Ceruti, SMD; Sonny Dimaiuta, SMD; Dominick Milidantri, SMD.

    Path forward

    By reusing equipment and tools developed with funding for RHIC and the LHC, and inspiring university collaborators to chip in their expertise, the nascent collaboration has taken these early steps on the path toward transforming PHENIX into sPHENIX. But the team hopes to get an official seal of approval—and, eventually, a budget—from DOE.

    The 2015 Long Range Plan for Nuclear Science—a set of recommendations made by the nation’s Nuclear Science Advisory Committee to leaders at DOE and the National Science Foundation—identifies the sPHENIX “state-of-the-art jet detector” as “essential” to probing the inner workings of QGP at shorter and shorter length scales, one of two “central goals” noted in the report for completing the scientific mission at RHIC. The report also notes that there is significant international interest in sPHENIX.

    “Right now we have a collaboration of 183 people, and growing,” Morrison said, with those scientists representing 58 institutions in 10 countries.

    Looking ahead and continuing the tradition of making the most of our nation’s investments in science, the physicists designing the sPHENIX upgrades say this transformed detector could largely be reused as a detector for a future Electron Ion Collider—the next priority nuclear physics project identified in the Long Range Plan.

    “Transforming PHENIX into sPHENIX would maximize the benefits derived from the investments already made to build RHIC by allowing us to fully understand the quark-gluon plasma,” Morrison said. “It’s what we need to do to complete the story of QGP discovery and to prepare for the coming research directions in nuclear physics.”

    sPHENIX R&D is supported by the DOE Office of Science and also by Brookhaven Lab’s Laboratory Directed Research and Development program, BNL Program Development, and in-kind contributions from collaborating universities.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition
    BNL Campus

    One of ten national laboratories overseen and primarily funded by the Office of Science of the U.S. Department of Energy (DOE), Brookhaven National Laboratory conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies and national security. Brookhaven Lab also builds and operates major scientific facilities available to university, industry and government researchers. The Laboratory’s almost 3,000 scientists, engineers, and support staff are joined each year by more than 5,000 visiting researchers from around the world.Brookhaven is operated and managed for DOE’s Office of Science by Brookhaven Science Associates, a limited-liability company founded by Stony Brook University, the largest academic user of Laboratory facilities, and Battelle, a nonprofit, applied science and technology organization.

Compose new post
Next post/Next comment
Previous post/Previous comment
Show/Hide comments
Go to top
Go to login
Show/Hide help
shift + esc

Get every new post delivered to your Inbox.

Join 574 other followers

%d bloggers like this: