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  • richardmitnick 1:48 pm on January 3, 2021 Permalink | Reply
    Tags: "What if the Universe has no end?", , , , , , , , , In fact it’s possible that time has existed forever., Mirror Universe theory, Multiverse theory, , , , Roger Penrose’s “Conformal Cyclic Cosmology” theory (CCC)   

    From BBC (UK): “What if the Universe has no end?” 

    From BBC (UK)

    19th January 2020 [Year End Wrap Up]
    Patchen Barss

    Credit: Getty Images.

    The Big Bang is widely accepted as being the beginning of everything we see around us, but other theories that are gathering support among scientists are suggesting otherwise.

    The usual story of the Universe has a beginning, middle, and an end.

    It began with the Big Bang 13.8 billion years ago when the Universe was tiny, hot, and dense. In less than a billionth of a billionth of a second, that pinpoint of a universe expanded to more than a billion, billion times its original size through a process called “cosmological inflation”.

    Next came “the graceful exit”, when inflation stopped. The universe carried on expanding and cooling, but at a fraction of the initial rate. For the next 380,000 years, the Universe was so dense that not even light could move through it – the cosmos was an opaque, superhot plasma of scattered particles. When things finally cooled enough for the first hydrogen atoms to form, the Universe swiftly became transparent. Radiation burst out in every direction, and the Universe was on its way to becoming the lumpy entity we see today, with vast swaths of empty space punctuated by clumps of particles, dust, stars, black holes, galaxies, radiation, and other forms of matter and energy.

    Eventually these lumps of matter will drift so far apart that they will slowly disappear, according to some models. The Universe will become a cold, uniform soup of isolated photons.

    The Universe we can currently see is made up of clumps of particles, dust, stars, black holes, galaxies, radiation. Credit: NASA/JPL-Caltech/ESA/CXC/STScI.

    It’s not a particularly dramatic ending, although it does have a satisfying finality.

    But what if the Big Bang wasn’t actually the start of it all?

    Perhaps the Big Bang was more of a “Big Bounce”, a turning point in an ongoing cycle of contraction and expansion. Or, it could be more like a point of reflection, with a mirror image of our universe expanding out the “other side”, where antimatter replaces matter, and time itself flows backwards. (There might even be a “mirror you” pondering what life looks like on this side.)

    Or, the Big Bang might be a transition point in a universe that has always been – and always will be – expanding. All of these theories sit outside mainstream cosmology, but all are supported by influential scientists.

    The growing number of these competing theories suggests that it might now be time to let go of the idea that the Big Bang marked the beginning of space and time. And, indeed, that it may even have an end.

    Many competing Big Bang alternatives stem from deep dissatisfaction with the idea of cosmological inflation.

    Scars left by the Big Bang in a weak microwave radiation that permeates the entire cosmos provides clues about what the early Universe looked like. Credit: NASA.

    “I have to confess, I never liked inflation from the beginning,” says Neil Turok, the former director of the Perimeter Institute for Theoretical Physics in Waterloo, Canada.

    “The inflationary paradigm has failed,” adds Paul Steinhardt, Albert Einstein professor in science at Princeton University, and proponent of a “Big Bounce” model.

    “I always regarded inflation as a very artificial theory,” says Roger Penrose, emeritus Rouse Ball professor of mathematics at Oxford University. “The main reason that it didn’t die at birth is that it was the only thing people could think of to explain what they call the ‘scale invariance of the Cosmic Microwave Background temperature fluctuations’.”

    The Cosmic Microwave Background (or “CMB”) has been a fundamental factor in every model of the Universe since it was first observed in 1965.

    CMB per ESA/Planck.

    It’s a faint, ambient radiation found everywhere in the observable Universe that dates back to that moment when the Universe first became transparent to radiation.

    The CMB is a major source of information about what the early Universe looked like. It is also a tantalising mystery for physicists. In every direction scientists point a radio telescope, the CMB looks the same, even in regions that seemingly could never have interacted with one another at any point in the history of a 13.8 billion-year- old universe.

    “The CMB temperature is the same on opposite sides of the sky and those parts of the sky would never have been in causal contact,” says Katie Mack, a cosmologist at North Carolina State University. “Something had to connect those two regions of the Universe in the past. Something had to tell that part of the sky to be the same temperature as that part of the sky.”

    Without some mechanism to even out the temperature across the observable Universe, scientists would expect to see much larger variations in different regions.

    Inflation offers a way to solve this so-called “homogeneity problem”. With a period of insane expansion stretching out the Universe so rapidly that almost the entire thing ended up far beyond the region we can observe and interact with. Our observable universe expanded from one tiny homogeneous region within that primordial hot mess, producing the uniform CMB. Other regions beyond what we can observe might look very different.

    Theoretical physicists are increasingly finding that inflation theory fails to account for the spread of matter and energy observed in the Universe. Credit: NASA, ESA.

    “Inflation seems to be the thing that has enough support from the data that we can take it as the default,” says Mack. ”It’s the one I teach in my classes. But I always say that we don’t know for sure that this happened. But it seems to fit the data pretty well, and is what most people would say is most likely.”


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

    HPHS Owls

    Lamda Cold Dark Matter Accerated Expansion of The universe http scinotions.com the-cosmic-inflation-suggests-the-existence-of-parallel-universes
    Alex Mittelmann, Coldcreation

    Alan Guth’s notes:

    Alan Guth’s original notes on inflation

    But there have always been shortcomings with the theory. Notably, there is no definitive mechanism to trigger inflationary expansion, or a testable explanation for how the graceful ending could happen. One idea put forward by proponents of inflation is that theoretical particles made up something called an “inflation field” that drove inflation and then decayed into the particles we see around us today.

    But even with tweaks like this, inflation makes predictions that have, at least thus far, not been confirmed. The theory says spacetime should be warped by primordial gravitational waves that ricocheted out across the Universe with the Big Bang. But while certain types of gravitational waves have been detected, none of these primordial ones have yet been found to support the theory.

    Quantum physics also forces inflation theories into very messy territory. Rare quantum fluctuations are predicted to cause inflation to break space up into an infinite number of patches with wildly different properties – a “multiverse” in which literally every imaginable outcome occurs.

    “The theory is completely indecisive,” says Steinhardt. “It can only say that the observable Universe might be like this or that or any other possibility you can imagine, depending on where we happen to be in the multiverse. Nothing is ruled out that is physically conceivable.”

    Steinhardt, who was one of the original architects of inflationary theory, ultimately got fed up with the lack of predictiveness and untestability.

    “Do we really need to imagine that there exist an infinite number of messy universes that we have never seen and never will see in order to explain the one simple and remarkably smooth Universe we actually observe?” he asks. “I say no. We have to look for a better idea.”

    Rather than being a beginning, the Big Bang could have been a moment of transition from one period of space and time to another – more of a bounce. Credit: Alamy.

    The problem might have to do with the Big Bang itself, and with the idea that there was a beginning to space and time.

    The “Big Bounce” theory agrees with the Big Bang picture of a hot, dense universe 13.8 billion years ago that began to expand and cool. But rather than being the beginning of space and time, that was a moment of transition from an earlier phase during which space was contracting.

    With a bounce rather than a bang, Steinhardt says, distant parts of the cosmos would have plenty of time to interact with each other, and to form a single smooth universe in which the sources of CMB radiation would have had a chance to even out.

    In fact, it’s possible that time has existed forever.

    “And if a bounce happened in our past, why could there not have been many of them?” says Steinhardt. “In that case, it is plausible that there is one in our future. Our expanding universe could start to contract, returning to that dense state and starting the bounce cycle again.”

    Steinhardt and Turok worked together on some early versions of the Big Bounce model, in which the Universe shrunk to such a tiny size that quantum physics took over from classical physics, leaving the predictions uncertain. But more recently, another of Steinhardt’s collaborators, Anna Ijjas, developed a model in which the Universe never gets so small that quantum physics dominates.

    “It’s a rather prosaic, conservative idea described at all times by classical equations,” Steinhardt says. “Inflation says there’s a multiverse, that there’s an infinite number of ways the Universe might come out, and we just happen to live in the one that is smooth and flat. That’s possible but not likely. This Big Bounce model says this is how the Universe must be.”

    Neil Turok has also been exploring another avenue for a simpler alternative to inflationary theory, the “Mirror Universe”. It predicts that another universe dominated by antimatter, but governed by the same physical laws as our own, is expanding outwards on the other side of the Big Bang – a kind of “anti-universe”, if you like.

    “I take one thing away from the observations of the last 30 years, which is that the Universe is unbelievably simple,” he says. “At large scales, it is not chaotic. It is not random. It’s incredibly ordered and regular and requires very few numbers to describe everything.”

    Our forward-time flowing universe could have a perfect reflection that also extends out in reverse from the event we call the Big Bang. Credit: Alamy.

    With this in mind, Turok sees no place for a multiverse, higher dimensions, or new particles to explain what can be seen when we look up at the heavens. The Mirror Universe offers all that – and might also solve one of the Universe’s big mysteries.

    If you add up all the known mass in a galaxy – stars, nebulae, black holes and so on – the total doesn’t create enough gravity to explain the motion within and between galaxies. The remainder seems to be made up of something we cannot currently see – Dark Matter. This mysterious stuff accounts for about 85% of the matter in the universe.

    The Mirror Universe model predicts that the Big Bang produced a particle known as “right-handed neutrinos” in abundance. While particle physicists have yet to directly see any of these particles, they are pretty sure they exist. And it is these that make up dark matter, according to those who support the Mirror Universe theory.

    “It’s the only particle on that list (of particles in the Standard Model) that has the two requisite properties that we haven’t directly observed it yet, and it could be stable,” says Latham Boyle, another leading proponent of the Mirror Universe theory and a colleague of Turok at the Perimeter Institute.

    Perhaps the most challenging alternative to the Big Bang and inflation is Roger Penrose’s “Conformal Cyclic Cosmology” theory (CCC). Like the Big Bounce, it involves a universe that might have existed forever. But in CCC, it never goes through a period of contraction – it only ever expands.

    “The view I have is that the Big Bang was not the beginning,” says Penrose. “The entire picture of what we know nowadays, the whole history of the Universe, is what I call one ‘aeon’ in a succession of aeons.”

    Penrose’s model predicts that much of the matter in the Universe will eventually be dragged into ultra-massive black holes. As the Universe expands and cools to near absolute zero, those black holes will “boil away” through a phenomenon called Hawking Radiation.

    “You have to think in terms of something like a googol years, which means a number one with 100 zeros,” says Penrose. “That’s the number of years or more for the really big ones to finally evaporate away. And then you’ve got a universe really dominated by photons (particles of light).”

    Penrose says at this point, the Universe begins to look much as it did at its start, setting the stage for the start of another aeon.

    Conformal Cyclic Cosmology predicts that much of the Universe will be pulled into enormous black holes that will then boil away. Credit: NASA/JPL-Caltech.

    One of the predictions of CCC is that there might be a record of the previous aeon in the cosmic microwave background radiation that originally inspired the inflation model. When hyper-massive black holes collide, the impact creates a huge release of energy in the form of gravitational waves. When giant black holes finally evaporate, they release a huge amount of energy in the form of low-frequency photons. Both of these phenomena are so powerful, Penrose says, that they can “burst through to the other side” of a transition from one aeon to the next, each leaving its own kind of “signal” embedded in the CMB like an echo from the past.

    Penrose calls the patterns left behind by evaporating black holes “Hawking Points”.

    For the first 380,000 years of the current aeon, these would have been nothing more than tiny points in the cosmos, but as the Universe has expanded, they would appear as “splotches” across the sky.

    Penrose has been working with Polish, Korean and Armenian cosmologists to see if these patterns can actually be found by comparing measurements of the CMB with thousands of random patterns.

    “The conclusion we come to is that we see these spots in the sky with 99.98% confidence,” Penrose says. The physics world has, however, remained largely skeptical of these results to date and there has been limited interest among cosmologists about even attempting to replicate Penrose’s analysis.

    It is unlikely that we will ever be able to directly observe what happened in the first moments after the Big Bang, let alone the moments before. The opaque superheated plasma that existed in the early moments will likely forever obscure our view. But there are other potentially observable phenomena such as primordial gravitational waves, primordial black holes, right-handed neutrinos, that could provide us some clues about which of the theories about our universe are correct.

    “As we develop new theories and new models of cosmology, those will give us other interesting predictions that can that we can look for,” says Mack. “The hope is not necessarily that we’re going to see the beginning more directly, but that maybe through some roundabout way we’ll better understand the structure of physics itself.”

    Until then, the story of our universe, its beginnings and whether it has an end, will continue to be debated.

    See the full article here .


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  • richardmitnick 10:18 am on May 14, 2018 Permalink | Reply
    Tags: , , , Multiverse theory, University of Sidney   

    From University of Sidney and Durham University via COSMOS: “Multiverse theory cops a blow after dark energy findings” 


    U Sidney bloc

    University of Sidney


    Durham U bloc

    Durham University



    14 May 2018
    Andrew Masterson

    Each universe in a multiverse contains different levels of dark energy, according to the dominant theory. Credit: Stolk/Getty Images

    The question of dark energy in one universe does not require others to provide an answer.

    A hypothetical multiverse seems less likely after modelling by researchers in Australia and the UK threw one of its key assumptions into doubt.

    The multiverse concept suggests that our universe is but one of many. It finds support among some of the world’s most accomplished physicists, including Brian Greene, Max Tegmark, Neil deGrasse Tyson and the late Stephen Hawking.

    One of the prime attractions of the idea is that it potentially accounts for an anomaly in calculations for dark energy.

    The mysterious force is thought to be responsible for the accelerating expansion of our own universe. Current theories, however, predict there should be rather more of it around than there appears to be. This throws up another set of problems: if the amount of dark energy around was as much as equations require – and that is many trillions of times the level that seems to exist – the universe would expand so rapidly that stars and planets would not form – and life, thus, would not be possible.

    The multiverse idea to an extent accounts for and accommodates this oddly small – but life-permitting – dark energy quotient. Essentially it permits a curiously self-serving explanation: there are a vast number of universes all with differing amounts of dark energy. We exist in one that has an amount low enough to permit stars and so on to form, and thus life to exist. (And we find ourselves here, runs the logic, because we couldn’t find ourselves anywhere else.)

    So far, so anthropic. But now a group of astronomers, including Luke Barnes from the University of Sydney in Australia and Jaime Salcido from Durham University in the UK, has published two papers in the journal Monthly Notices of the Royal Astronomical Society [Galaxy formation efficiency and the multiverse explanation of the cosmological constant with EAGLE simulations and The impact of dark energy on galaxy formation. What does the future of our Universe hold? that show the dark energy and star formation balance isn’t quite as fine as previous estimates have suggested.

    The team created simulations of the universe using the supercomputer architecture contained within the Evolution and Assembly of GaLaxies and their Environments (EAGLE) project. This is a UK-based collaboration that models some 10,000 galaxies over a distance of 300 million-light years, and compares the results with actual observations from the Hubble Telescope and other observatories.

    The simulations allowed the researchers to adjust the amount of dark energy in the universe and watch what happened.

    The results were a surprise. The research revealed that the amount of dark energy could be increased a couple of hundred times – or reduced equally drastically – without substantially affecting anything else.

    “For many physicists, the unexplained but seemingly special amount of dark energy in our universe is a frustrating puzzle,” says Salcido.

    “Our simulations show that even if there was much more dark energy or even very little in the universe then it would only have a minimal effect on star and planet formation.”

    And this, he suggests, implies that life could potentially exist in many multiverse universes – ironically enough, an uncomfortable conclusion.

    “The multiverse was previously thought to explain the observed value of dark energy as a lottery – we have a lucky ticket and live in the universe that forms beautiful galaxies which permit life as we know it,” says Barnes.

    “Our work shows that our ticket seems a little too lucky, so to speak. It’s more special than it needs to be for life. This is a problem for the multiverse; a puzzle remains.”

    It is a puzzle that goes right to the heart of the matter: if the dark energy assumptions are flawed, does a multiverse even exist? The researchers acknowledge that their results do not preclude it – but they do diminish the likelihood.

    “The formation of stars in a universe is a battle between the attraction of gravity, and the repulsion of dark energy,” says co-author Richard Bower, also from Durham University.

    “We have found in our simulations that universes with much more dark energy than ours can happily form stars. So why such a paltry amount of dark energy in our universe?

    “I think we should be looking for a new law of physics to explain this strange property of our universe, and the multiverse theory does little to rescue physicists’ discomfort.”

    See the full article here .

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    Durham U campus

    Durham University is distinctive – a residential collegiate university with long traditions and modern values. We seek the highest distinction in research and scholarship and are committed to excellence in all aspects of education and transmission of knowledge. Our research and scholarship affect every continent. We are proud to be an international scholarly community which reflects the ambitions of cultures from around the world. We promote individual participation, providing a rounded education in which students, staff and alumni gain both the academic and the personal skills required to flourish.

    U Sidney campus

    Our founding principle as Australia’s first university was that we would be a modern and progressive institution. It’s an ideal we still hold dear today.

    When Charles William Wentworth proposed the idea of Australia’s first university, University of Sidney, in 1850, he imagined “the opportunity for the child of every class to become great and useful in the destinies of this country”.

    We’ve stayed true to that original value and purpose by promoting inclusion and diversity for the past 160 years.

    It’s the reason that, as early as 1881, we admitted women on an equal footing to male students. Oxford University didn’t follow suit until 30 years later, and Jesus College at Cambridge University did not begin admitting female students until 1974.

    It’s also why, from the very start, talented students of all backgrounds were given the chance to access further education through bursaries and scholarships.

    Today we offer hundreds of scholarships to support and encourage talented students, and a range of grants and bursaries to those who need a financial helping hand.

  • richardmitnick 2:17 pm on February 24, 2018 Permalink | Reply
    Tags: , , , , , , Multiverse theory, Why Haven't We Bumped Into Another Universe Yet?   

    From Ethan Siegel: “Why Haven’t We Bumped Into Another Universe Yet?” 

    From Ethan Siegel
    Feb 24, 2018

    The multiverse idea states that there are an arbitrarily large number of Universes like our own, but that doesn’t necessarily mean there’s another version of us out there, and it certainly doesn’t mean there’s any chance of running into an alternate version of yourself… or anything from another Universe at all. Lee Davy / flickr.

    The Universe we inhabit is vast, full of matter and energy, and expanding at a tremendous clip. Looking billions of light years away, we can see billions of years into our ancient past, finding evidence of newly-forming planets, stars, and galaxies. We’ve seen so far back that we’ve identified clouds of gas that have never yet formed a single star, and found galaxies from when the Universe was only 3% of its current age. Most spectacularly, we can actually see the leftover glow from the Big Bang, from a time when the Universe was a mere 380,000 years old. Yet in all of this cosmic enormity, we’ve never found evidence that our Universe has bumped into another one in this vast Multiverse. Why not? That’s what Rod Russo wants to know:

    “If the Multiverse Theory is true, shouldn’t our expanding universe have bumped into another universe by now? After all, our universe is now so large that some describe it as “infinite” in size.”

    This is not only what logic dictates, it’s what no less an authority than Roger Penrose has claimed. But Penrose — and conventional wisdom — are both wrong here. Our Universe is, and should be, isolated and alone in the Multiverse.

    Artist’s logarithmic scale conception of the observable universe. Note that we’re limited in how far we can see back by the amount of time that’s occurred since the hot Big Bang: 13.8 billion years, or (including the expansion of the Universe) 46 billion light years. Anyone living in our Universe, at any location, would see almost exactly the same thing from their vantage point. Wikipedia user Pablo Carlos Budassi.

    Although there’s a lot of hype and controversy surrounding it, there’s an extremely strong physical motivation for the existence of the Multiverse. If you combine two of our leading ideas about how the Universe works, cosmic inflation and quantum physics, it’s all but inescapable that we’ll conclude that our Universe resides in a Multiverse. Coming along for the ride is another conclusion: that every single Universe that gets created — that every hot Big Bang that ensues — is immediately and forever causally disconnected from all the others, eternally into the future. Here’s how that happens, and here’s how we know.

    The expanding Universe, full of galaxies and the complex structure we observe today, arose from a smaller, hotter, denser, more uniform state. But what lies outside the observable Universe, by definition, cannot be observed. C. Faucher-Giguère, A. Lidz, and L. Hernquist, Science 319, 5859 (47).

    Cosmic inflation came about as an add-on to the Big Bang, successfully providing a mechanism for explaining why it began with certain conditions.

    Alan Guth, Highland Park High School 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

    Alan Guth’s notes:

    In particular, inflation provided answer to the questions of:

    why the Universe was the same temperature everywhere,
    why it was so spatially flat,
    and why there were no leftover high-energy relics like magnetic monopoles,

    while simultaneously making new predictions that could be tested. These predictions included a specific spectrum for the density fluctuations the Universe was born with, a maximum temperature that the Universe achieved in the early stages of the hot Big Bang, the existence of fluctuations on scales larger than the cosmic horizon, and a particular spectrum of gravitational wave fluctuations. All of these, except the very last, have since been observationally confirmed.

    Inflation set up the hot Big Bang and gave rise to the observable Universe we have access to, but we can only measure the last tiny fraction of a second of inflation’s impact on our Universe. This is enough, however, to give us a large slew of predictions to go out an look for, many of which have already been observationally confirmed. E. Siegel, with images derived from ESA/Planck and the DoE/NASA/ NSF interagency task force on CMB research

    What cosmic inflation is, exactly, is a period prior [?*] to the Big Bang where the Universe is dominated by the energy inherent to space itself. Unlike today, where the value of dark energy is extremely small, inflation posits that it was extremely large: larger by far than even the energy density when the Universe was full of matter and radiation in the extremely hot, early stages after the Big Bang. Since the expansion was dominated by the energy inherent to space, the rate of expansion was exponential, meaning that new space was continuously and rapidly created. If the Universe doubled in size after a certain amount of time, then after ten times that amount of time passed, it’d be 210, or over 1000, times as large in all dimensions. In extremely short order, any non-flat, matter-containing region of space would become indistinguishable from flat, and would have all the matter particles inflated away so that no two would ever meet.

    Inflation causes space to expand exponentially, which can very quickly result in any pre-existing curved space appearing flat. E. Siegel (L); Ned Wright’s cosmology tutorial (R).

    On the other hand, inflation must come to an end at some point. The energy inherent to space cannot remain there forever, otherwise the Big Bang never would have occurred [?*], and the Universe as we know it would never have come to be. Somehow, that energy needs to get transferred from the fabric of space itself and dumped into matter and radiation. A nice way to visualize this is to view inflation as a field that occurs when a ball is at the top of a hill. As long as the ball remains up high, inflation, and this exponential expansion, continues. But in order for inflation to end, whatever quantum field is responsible for it has to roll from the high-energy, unstable state that drives inflation down into a low-energy, equilibrium state. That transition, and “rolling” down into the valley, is what causes inflation to come to an end, and create the hot Big Bang.

    When cosmic inflation occurs, the energy inherent in space is large, as it is at the top of this hill. As the ball rolls down into the valley, that energy converts into particles. E. Siegel.

    But here’s the kicker: what I just described is how a classical field works, but we just said that inflation has to be, like all physical fields, an inherently quantum one. Like all quantum fields, it’s described by a wavefunction, with the probability of that wave spreading out over time. If the value of the field is rolling slowly-enough down the hill, then the quantum spreading of the wavefunction will be faster than the roll, meaning that it’s possible — even probable — for inflation to wind up farther away from ending and giving rise to a Big Bang as time goes on.

    If inflation is a quantum field, then the field value spreads out over time, with different regions of space taking different realizations of the field value. In many regions, the field value will wind up in the bottom of the valley, ending inflation, but in many more, inflation will continue, arbitrarily far into the future. E. Siegel / Beyond The Galaxy.

    Because space is expanding at an exponential rate during inflation, this means that exponentially more regions of space are being created as time goes on. The thing is, inflation isn’t compelled to end everywhere at once; different regions will see the value of their quantum fields spread out by different amounts and in different directions over time! In a few regions, inflation will come to an end, as long as the field rolls down into the valley. But in others, inflation will continue on, giving rise to more and more space, where it continues to expand exponentially.

    Wherever inflation occurs (blue cubes), it gives rise to exponentially more regions of space with each step forward in time. Even if there are many cubes where inflation ends (red Xs), there are far more regions where inflation will continue on into the future. The fact that this never comes to an end is what makes inflation ‘eternal’ once it begins. E. Siegel / Beyond The Galaxy.

    This is where the phenomenon known as eternal inflation, and the idea of a multiverse, comes from. Where inflation ends, we get a hot Big Bang and a Universe — of which we can observe part of the one we’re in — very much like our own. (Denoted by the red “X” above.) But surrounding each of those regions where a hot Big Bang occurs is one where inflation doesn’t end, and the exponential expansion continues. In those regions, more inflating space is produced, driving apart the regions where inflation ended at a faster rate than they’re capable of expanding at. This gives rise to other regions that will have hot Big Bangs, but each and every one of them will be causally disconnected from our own, at the moment of the hot Big Bang and forever into the future.

    If you picture the Multiverse as an enormous ocean, you can picture the individual Universes where a hot Big Bang occurs as little bubbles appearing in it. The bubbles, like real air bubbles that rise from the bottom of the ocean, will expand as time goes on, just as our own Universe is expanding. But unlike the liquid water of the ocean, the “ocean” of inflating spacetime keeps on expanding at a faster rate than the bubbles themselves can ever expand. As long as the space between them continues to inflate, and inflation predicts they will for an eternity, no two bubbles should ever collide. Unlike the boiling water on your stove, the bubbles don’t percolate.

    It would be an enormous surprise that runs counter to inflation and quantum theory’s predictions if any two Universes ever did collide. While bubble-wall collisions might leave a telltale sign on our Universe, we’ve examined the leftover glow from the Big Bang in gory detail, and no evidence for such a collision exists. Thankfully for our most robust theories of the early Universe, this is exactly in line with what’s been predicted. The reason we don’t see evidence for our Universe colliding with another is because our Universe has never collided with another one, just as our leading theories predict. Anyone who tells you otherwise has got some serious explaining to do.

    *I question Siegel’s assertion that inflation occurred prior to the Big Bang. I have never seen that and Alan Guth did not see that. From Wikipedia:

    “In physical cosmology, cosmic inflation, cosmological inflation, or just inflation, is a theory of exponential expansion of space in the early universe. The inflationary epoch lasted from 10−36 seconds after the conjectured Big Bang singularity to sometime between 10^−33 and 10^−32 seconds after the singularity. Following the inflationary period, the Universe continues to expand, but at a less rapid rate…As a junior particle physicist, [Alan] Guth developed the idea of cosmic inflation in 1979 at Cornell and gave his first seminar on the subject in January 1980.Moving on to Stanford University Guth formally proposed the idea of cosmic inflation in 1981, the idea that the nascent universe passed through a phase of exponential expansion that was driven by a positive vacuum energy density (negative vacuum pressure). The results of the WMAP mission in 2006 made the case for cosmic inflation very compelling.”

    I mean really, Ethan, how can you post inflation prior to the Big Bang? I have seen no one posit this before.

    See the full article here .

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    “Starts With A Bang! is a blog/video blog about cosmology, physics, astronomy, and anything else I find interesting enough to write about. I am a firm believer that the highest good in life is learning, and the greatest evil is willful ignorance. The goal of everything on this site is to help inform you about our world, how we came to be here, and to understand how it all works. As I write these pages for you, I hope to not only explain to you what we know, think, and believe, but how we know it, and why we draw the conclusions we do. It is my hope that you find this interesting, informative, and accessible,” says Ethan

  • richardmitnick 1:49 pm on February 1, 2018 Permalink | Reply
    Tags: , Multiverse theory, , Universes with no weak force might still have stars and life   

    From ScienceNews: “Universes with no weak force might still have stars and life” 


    January 30, 2018
    Lisa Grossman

    An alternate cosmos could do without one of the fundamental forces, physicists say.

    MANY WORLDS Alternate universes with different laws of physics could still host galaxies, stars and planets, a new study suggests. Juergen Faelchle/Shutterstock

    Not all fundamental forces are created equal. An alternate universe that lacks the weak nuclear force — one of the four fundamental forces that govern all matter in our universe — could still form galaxies, stars, planets and perhaps life, according to calculations published online January 18 at arXiv.org.

    Scientists have long thought that our universe wouldn’t exist, or at least wouldn’t support life, without certain physical laws. For instance, if gravity were much stronger than it is, most matter would collapse into black holes; if it were weaker, the universe wouldn’t form structures such as galaxies or planets. The strong nuclear force holds atomic nuclei together, and the electromagnetic force carries light across the universe.

    “Those three forces, gravity, strong and electromagnetic, are part of the deal,” says theoretical physicist Fred Adams of the University of Michigan in Ann Arbor. But the weak nuclear force — responsible for making neutrons decay into protons, electrons and neutrinos — might not be so essential (SN: 4/29/17, p. 22). “That’s the only one you can get rid of entirely without messing everything up,” he says.

    A previous study [Physical Review D] had argued that a universe lacking the weak force could exist. Some physicists think our universe is just one in an infinite multiverse, where many different cosmoses exist side-by-side, possibly governed by different physical rules. We live in this one simply because we couldn’t live anywhere else (SN Online: 10/10/14), some scientists say.

    “People talk about universes like they’re very fine-tuned; if you changed things just a little bit, life would die,” Adams says. But “the universe and stars have a lot more pathways to success.”

    In the new research, he and his colleagues simulated how matter was created in the Big Bang and then condensed into stars, but without the effects of the weak nuclear force. In our universe, one consequence of neutron decay is that most of the universe is made of hydrogen, which consists of a single proton and electron. Stars, in their hot cores, fuse protons into helium and heavier elements and then scatter them into space, helping to create everything from planets to physicists. But with no weak force, a universe would be filled with neutrons that didn’t decay — a dead end for building heavier elements.

    The only way such a universe could create complex matter would be to have started out with fewer neutrons and more free protons than our universe did. That way, neutrons and protons could link up and make deuterium, also called heavy hydrogen. So Adams and his colleagues tweaked the simulated universe’s initial neutron and proton content, too.

    Stars fueled with deuterium would still shine, the simulations showed, but the objects would look different. Burning deuterium is more efficient than burning hydrogen, so these stars would be a little hotter, larger and redder than our stars. But the stars could still create all the elements of the periodic table up to iron, and stellar winds could carry those elements out into space.

    Any planets that formed would have water made with deuterium instead of hydrogen, which is toxic to life in our universe. “But if life had to evolve with deuterated water … it might be OK,” Adams says.

    Adams and his colleagues are some of the first to explore the consequences of a “weakless” universe seriously by tweaking the numbers, says Martin Rees of the University of Cambridge, who was not involved in either study.

    The paper does not help figure out if the multiverse is real, though. “We hope that eventually we’ll know,” Rees says, but “I’m not holding my breath.”

    See the full article here .

    Science News is edited for an educated readership of professionals, scientists and other science enthusiasts. Written by a staff of experienced science journalists, it treats science as news, reporting accurately and placing findings in perspective. Science News and its writers have won many awards for their work; here’s a list of many of them.

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  • richardmitnick 8:27 am on September 14, 2017 Permalink | Reply
    Tags: , Brian Greene, Cosmology- origins of the universe, , Multiverse theory, , , , , Unified theory of physics,   

    From Harvard Gazette: “A master of explaining the universe” 

    Harvard University
    Harvard University

    September 13, 2017
    Colleen Walsh

    Brian Greene ’84, a Columbia University theoretical physicist and mathematician, has made it his mission to illuminate the wonders of the universe for non-scientists. Photo by Greg Kessler/World Science Festival

    Harvard Overseer and Columbia physicist Brian Greene seeks wider audience for the wonders of science.

    He is the founder of the World Science Festival, the author of numerous best-selling books, including the Pulitzer Prize finalist “The Elegant Universe,” and an expert at explaining knotty concepts. Now he’s back at Harvard. On Sept. 19, Brian Greene ’84, Harvard Overseer and Columbia University theoretical physicist and mathematician, will explore shifting ideas of space, time, and reality in a talk at the Radcliffe Institute for Advanced Study. The Gazette caught up with Greene to ask him about his years at Harvard, his passion for science, and how he defines superstring theory in a tweet.

    GAZETTE: Where did your initial interest in math and physics come from?

    GREENE: When I was a kid growing up in Manhattan I was deeply fascinated with mathematics, and at a young age my dad taught me the basics of arithmetic. I was captivated from then on by the ability to use a few simple rules to undertake calculations that no one had ever done before. Now, most of these calculations weren’t ever done because they weren’t interesting, but for a kid to be able to do something new is deeply thrilling. Later on, when I learned in high school and most forcefully when I got to college at Harvard that math isn’t merely a game but it’s something that can help you understand what happens out there in the real universe, then I was kind of hooked for life.

    GAZETTE: Were there any classes or professors that had a big impact on you at Harvard?

    GREENE: Oh, huge. Howard Georgi was my freshman physics professor, and he had a deep impact on my love of the subject. There’s now a mathematician who wasn’t at Harvard when I was an undergrad but whom I worked with extensively as a graduate student and then he moved to Harvard, Shing-Tung Yau in the Mathematics Department. He had a deep impact on me. The Harvard faculty had quite a formative impact on me across the years.

    GAZETTE: I know you are famous for being able to explain awesome scientific concepts. In the age of social media, can you define superstring theory in a tweet?

    GREENE: Superstring theory is our best attempt to realize Einstein’s dream of the unified theory. #unification.

    GAZETTE: So break that down for me, and this doesn’t have to be in a tweet format. What is the unified theory of physics and why is it so important?

    GREENE: Einstein envisioned that there might be a master law of physics, perhaps captured by a single mathematical equation that would be so powerful that in principle it could describe every physical process in the universe — the big stuff, the small stuff, and everything in between. And he believed it so deeply that he pursued it relentlessly for the last 30 years of his life. On various occasions Einstein announced that he had the unified theory, always, however, to have to retract that sometime later when he realized that his latest proposal didn’t quite work. In the end it was a very frustrating experience for him. And when he died, that dream of unification died with him. But about 10 or 15 years later some scientist stumbled upon a new approach — this approach called superstring theory — and over the course of decades realized that this may in fact be the unified theory that Einstein was looking for. And that’s what we have been developing ever since.

    GAZETTE: What has been the main focus of your work for the last several years?

    GREENE: I have been working on issues of cosmology, origins of the universe. I’ve been working on the possibility of a multiverse — that we might live in a reality that comprises more than one universe. I’ve been working on some strange features of quantum mechanics called quantum entanglement, where distant objects can somehow act as though they are sitting right next to each other. Again this is a discovery that sort of goes back to Einstein himself, so things in that domain have been my main focus of late.

    GAZETTE: Tell me more about multiple universes.

    GREENE: Well, it’s a curious idea because for most people the word universe means everything: all that there is. But developments over the past couple of decades have convinced many of us that there is at least a possibility that what we have long thought to be everything is actually perhaps just a small part of a much bigger reality. And that bigger reality might have other realms that would rightly be called universes of their own, and if that’s the case then the grand picture of reality involves a whole collection of universes, and that’s why we no longer use the word universe to describe all there is … we speak of “multi” — there are multiverses because of this multiplicity of universes.

    GAZETTE: Is there current or future research that you could see really changing the nature of how we see the universe?

    GREENE: My own feeling, and it’s shared by colleagues, is that the next breakthrough will come when we deeply understand the fundamental ingredients of space and time themselves. And this is an open question. Just like matter is made up of atoms and molecules, could it be that space and time are themselves made up of more fundamental constituents? In fact, this is what I will be talking about at Radcliffe, recent work that at least hints at an answer to what the ingredients of space and time might actually be.

    GAZETTE: What has inspired you to work to make science understandable?

    GREENE: My view of science is not that it’s merely an effort to unearth the basic laws of physics, but I view it more as a very human undertaking to see how we fit into the grand scheme of things and to answer the questions that have been asked since the time we could ask questions: Where did we come from? What are we made of? How did the universe come to be? What is time? What will happen in the distant future? All these questions I think speak deeply to who we are as a species, and for the vast majority of people to be cut off from the most up-to-date thinking on these deep questions because they don’t speak mathematics, they don’t have a graduate degree in physics, I think that’s tragic. So for decades now I’ve felt that part of my charge is to bring these ideas to a wider audience, to make them available to anyone who has a curiosity and a little bit of stick-to-itiveness to push through some deep, difficult, but ultimately gratifying ideas.

    GAZETTE: If you weren’t a physicist what would you be?

    GREENE: Well, if I was starting out today I think I would probably go into neuroscience. I like to think of the big questions. Where did the universe come from? Where did life come from? And where does mind come from? And for those I think the time is really ripe to understand the nature of intelligence and thought. I think there are going to be great, great breakthroughs in that area in the next couple of decades.

    GAZETTE: Favorite physicist?

    GREENE: There’s nobody who compares with Isaac Newton in terms of the leap that he pushed humanity through from the way we understood the world before he began to think about it until after he existed.

    GAZETTE: What is your take on Voyager?

    GREENE: The “Star Trek” version or the real version?

    GAZETTE: The real version.

    GREENE: I think it’s a great symbol of who we are as a species. We are explorers. We are deeply committed to understanding the universe, and to envision these little spacecraft that have left the solar system and they are floating out there in the great unknown as harbingers, if you will, of human life back on the planet is a deeply moving picture and one that really captures who we are.

    See the full article here .

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    Harvard University campus
    Harvard is the oldest institution of higher education in the United States, established in 1636 by vote of the Great and General Court of the Massachusetts Bay Colony. It was named after the College’s first benefactor, the young minister John Harvard of Charlestown, who upon his death in 1638 left his library and half his estate to the institution. A statue of John Harvard stands today in front of University Hall in Harvard Yard, and is perhaps the University’s best known landmark.

    Harvard University has 12 degree-granting Schools in addition to the Radcliffe Institute for Advanced Study. The University has grown from nine students with a single master to an enrollment of more than 20,000 degree candidates including undergraduate, graduate, and professional students. There are more than 360,000 living alumni in the U.S. and over 190 other countries.

  • richardmitnick 6:32 am on June 14, 2017 Permalink | Reply
    Tags: , , , , , Multiverse theory, Philosophy ans Philosophers   

    From aeon: “The idea of creating a new universe in the lab is no joke” 



    Zeeya Merali

    Artwork illustrating the concept of an alternate ‘bubble’ universe in which our universe (left) is not the only one. Some scientists think that bubble universes may pop into existence all the time, and occasionally nudge ours. NASA/JPL-Caltech/R. Hurt (IPAC)

    Physicists aren’t often reprimanded for using risqué humour in their academic writings, but in 1991 that is exactly what happened to the cosmologist Andrei Linde at Stanford University. He had submitted a draft article entitled Hard Art of the Universe Creation to the journal Nuclear Physics B. In it, he outlined the possibility of creating a universe in a laboratory: a whole new cosmos that might one day evolve its own stars, planets and intelligent life. Near the end, Linde made a seemingly flippant suggestion that our Universe itself might have been knocked together by an alien ‘physicist hacker’. The paper’s referees objected to this ‘dirty joke’; religious people might be offended that scientists were aiming to steal the feat of universe-making out of the hands of God, they worried. Linde changed the paper’s title and abstract but held firm over the line that our Universe could have been made by an alien scientist. ‘I am not so sure that this is just a joke,’ he told me.

    Fast-forward a quarter of a century, and the notion of universe-making – or ‘cosmogenesis’ as I dub it – seems less comical than ever. I’ve travelled the world talking to physicists who take the concept seriously, and who have even sketched out rough blueprints for how humanity might one day achieve it. Linde’s referees might have been right to be concerned, but they were asking the wrong questions. The issue is not who might be offended by cosmogenesis, but what would happen if it were truly possible. How would we handle the theological implications? What moral responsibilities would come with fallible humans taking on the role of cosmic creators?

    Theoretical physicists have grappled for years with related questions as part of their considerations of how our own Universe began. In the 1980s, the cosmologist Alex Vilenkin at Tufts University in Massachusetts came up with a mechanism through which the laws of quantum mechanics could have generated an inflating universe from a state in which there was no time, no space and no matter. There’s an established principle in quantum theory that pairs of particles can spontaneously, momentarily pop out of empty space. Vilenkin took this notion a step further, arguing [Physical Review D] that quantum rules could also enable a minuscule bubble of space itself to burst into being from nothing, with the impetus to then inflate to astronomical scales. Our cosmos could thus have been burped into being by the laws of physics alone. To Vilenkin, this result put an end to the question of what came before the Big Bang: nothing. Many cosmologists have made peace with the notion of a universe without a prime mover, divine or otherwise.

    At the other end of the philosophical spectrum, I met with Don Page, a physicist and evangelical Christian at the University of Alberta in Canada, noted for his early collaboration with Stephen Hawking [Physical Review D] on the nature of black holes. To Page, the salient point is that God created the Universe ex nihilo – from absolutely nothing. The kind of cosmogenesis envisioned by Linde, in contrast, would require physicists to cook up their cosmos in a highly technical laboratory, using a far more powerful cousin of the Large Hadron Collider near Geneva. It would also require a seed particle called a ‘monopole’ (which is hypothesised to exist by some models of physics, but has yet to be found). The idea goes that if we could impart enough energy to a monopole, it will start to inflate.

    Rather than growing in size within our Universe, the expanding monopole would bend spacetime within the accelerator to create a tiny wormhole tunnel leading to a separate region of space. From within our lab we would see only the mouth of the wormhole; it would appear to us as a mini black hole, so small as to be utterly harmless. But if we could travel into that wormhole, we would pass through a gateway into a rapidly expanding baby universe that we had created.

    We have no reason to believe that even the most advanced physics hackers could conjure a cosmos from nothing at all, Page argues. Linde’s concept of cosmogenesis, audacious as it might be, is still fundamentally technological. Page, therefore, sees little threat to his faith. On this first issue, then, cosmogenesis would not necessarily upset existing theological views.

    But flipping the problem around, I started to wonder: what are the implications of humans even considering the possibility of one day making a universe that could become inhabited by intelligent life? As I discuss in my book A Big Bang in a Little Room (2017), current theory suggests that, once we have created a new universe, we would have little ability to control its evolution or the potential suffering of any of its residents. Wouldn’t that make us irresponsible and reckless deities? I posed the question to Eduardo Guendelman, a physicist at Ben Gurion University in Israel, who was one of the architects of the cosmogenesis model back in the 1980s. Today, Guendelman is engaged in research that could bring baby-universe-making within practical grasp. I was surprised to find that the moral issues did not cause him any discomfort. Guendelman likens scientists pondering their responsibility over making a baby universe to parents deciding whether or not to have children, knowing they will inevitably introduce them to a life filled with pain as well as joy.

    Other physicists are more wary. Nobuyuki Sakai of Yamaguchi University in Japan, one of the theorists who proposed [Phys.Rev. D] that a monopole could serve as the seed for a baby universe, admitted that cosmogenesis is a thorny issue that we should ‘worry’ about as a society in the future. But he absolved himself of any ethical concerns today. Although he is performing the calculations that could allow cosmogenesis, he notes that it will be decades before such an experiment might feasibly be realised. Ethical concerns can wait.

    Many of the physicists I approached were reluctant to wade into such potential philosophical quandaries. So I turned to a philosopher, Anders Sandberg at the University of Oxford, who contemplates the moral implications of creating artificial sentient life in computer simulations. He argues that the proliferation of intelligent life, regardless of form, can be taken as something that has inherent value. In that case, cosmogenesis might actually be a moral obligation.

    Looking back on my numerous conversations with scientists and philosophers on these issues, I’ve concluded that the editors at Nuclear Physics B did a disservice both to physics and to theology. Their little act of censorship served only to stifle an important discussion. The real danger lies in fostering an air of hostility between the two sides, leaving scientists afraid to speak honestly about the religious and ethical consequences of their work out of concerns of professional reprisal or ridicule.

    We will not be creating baby universes anytime soon, but scientists in all areas of research must feel able to freely articulate the implications of their work without concern for causing offence. Cosmogenesis is an extreme example that tests the principle. Parallel ethical issues are at stake in the more near-term prospects of creating artificial intelligence or developing new kinds of weapons, for instance. As Sandberg put it, although it is understandable that scientists shy away from philosophy, afraid of being thought weird for veering beyond their comfort zone, the unwanted result is that many of them keep quiet on things that really matter.

    As I was leaving Linde’s office at Stanford, after we’d spent a day riffing on the nature of God, the cosmos and baby universes, he pointed at my notes and commented ruefully: ‘If you want to have my reputation destroyed, I guess you have enough material.’ This sentiment was echoed by a number of the scientists I had met, whether they identified as atheists, agnostics, religious or none of the above. The irony was that if they felt able to share their thoughts with each other as openly as they had with me, they would know that they weren’t alone among their colleagues in pondering some of the biggest questions of our being.

    See the full article here .

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  • richardmitnick 8:57 pm on May 5, 2017 Permalink | Reply
    Tags: , , , Is this the only universe?, Multiverse theory,   

    From Symmetry: “Is this the only universe?” 

    Symmetry Mag


    07/28/15 [Never saw this before in social media.]
    Laura Dattaro

    No image credit

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

    Human history has been a journey toward insignificance.

    As we’ve gained more knowledge, we’ve had our planet downgraded from the center of the universe to a chunk of rock orbiting an average star in a galaxy that is one among billions.

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

    So it only makes sense that many physicists now believe that even our universe might be just a small piece of a greater whole. In fact, there may be infinitely many universes, bubbling into existence and growing exponentially. It’s a theory known as the multiverse.

    Multiverse. Image credit: public domain, retrieved from https://pixabay.com/

    One of the best pieces of evidence for the multiverse was first discovered in 1998, when physicists realized that the universe was expanding at ever increasing speed. They dubbed the force behind this acceleration dark energy.

    The universe has been expanding since the Big Bang kickstarted the growth about 13.8 billion years.

    The value of its energy density, also known as the cosmological constant [Λ], is bizarrely tiny: 120 orders of magnitude smaller than theory says it should be.

    For decades, physicists have sought an explanation for this disparity. The best one they’ve come up with so far, says Yasunori Nomura, a theoretical physicist at the University of California, Berkeley, is that it’s only small in our universe. There may be other universes where the number takes a different value, and it is only here that the rate of expansion is just right to form galaxies and stars and planets where people like us can observe it. “Only if this vacuum energy stayed to a very special value will we exist,” Nomura says. “There are no good other theories to understand why we observe this specific value.”

    For further evidence of a multiverse, just look to string theory, which posits that the fundamental laws of physics have their own phases, just like matter can exist as a solid, liquid or gas. If that’s correct, there should be other universes where the laws are in different phases from our own—which would affect seemingly fundamental values that we observe here in our universe, like the cosmological constant. “In that situation you’ll have a patchwork of regions, some in this phase, some in others,” says Matthew Kleban, a theoretical physicist at New York University.

    These regions could take the form of bubbles, with new universes popping into existence all the time. One of these bubbles could collide with our own, leaving traces that, if discovered, would prove other universes are out there. We haven’t seen one of these collisions yet, but physicists are hopeful that we might in the not so distant future.

    If we can’t find evidence of a collision, Kleban says, it may be possible to experimentally induce a phase change—an ultra-high-energy version of coaxing water into vapor by boiling it on the stove. You could effectively prove our universe is not the only one if you could produce phase-transitioned energy, though you would run the risk of it expanding out of control and destroying the Earth. “If those phases do exist—if they can be brought into being by some kind of experiment—then they certainly exist somewhere in the universe,” Kleban says.

    No one is yet trying to do this.

    There might be a (relatively) simpler way. Einstein’s general theory of relativity implies that our universe may have a “shape.” It could be either positively curved, like a sphere, or negatively curved, like a saddle. A negatively curved universe would be strong evidence of a multiverse, Nomura says. And a positively curved universe would show that there’s something wrong with our current theory of the multiverse, while not necessarily proving there’s only one. (Proving that is a next-to-impossible task. If there are other universes out there that don’t interact with ours in any sense, we can’t prove whether they exist.)

    In recent years, physicists have discovered that the universe appears almost entirely flat. But there’s still a possibility that it’s slightly curved in one direction or the other, and Nomura predicts that within the next few decades, measurements of the universe’s shape could be precise enough to detect a slight curvature. That would give physicists new evidence about the nature of the multiverse. “In fact, this evidence will be reasonably strong since we do not know any other theory which may naturally lead to a nonzero curvature at a level observable in the universe,” Nomura says.

    If the curvature turned out to be positive, theorists would face some very difficult questions. They would still be left without an explanation for why the expansion rate of the universe is what it is. The phases within string theory would also need re-examining. “We will face difficult problems,” Nomura says. “Our theory of dark energy is gone if it’s the wrong curvature.”

    But with the right curvature, a curved universe could reframe how physicists look at values that, at present, appear to be fundamental. If there were different universes with different phases of laws, we might not need to seek fundamental explanations for some of the properties our universe exhibits.

    And it would, of course, mean we are tinier still than we ever imagined. “It’s like another step in this kind of existential crisis,” Kleban says. “It would have a huge impact on people’s imaginations.”

    See the full article here .

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    Symmetry is a joint Fermilab/SLAC publication.

  • richardmitnick 12:39 pm on March 2, 2017 Permalink | Reply
    Tags: , Hugh Everett III, , Multiverse theory   

    From Nautilus: “Evil Triumphs in These Multiverses, and God Is Powerless” 



    March 2, 2017
    Dean Zimmerman

    The challenge that the multiverse poses for the idea of an all-good, all-powerful God is often focused on fine-tuning. If there are infinite universes, then we don’t need a fine tuner to explain why the conditions of our universe are perfect for life, so the argument goes. But some kinds of multiverse pose a more direct threat. The many-worlds interpretation of quantum physicist Hugh Everett III and the modal realism of cosmologist Max Tegmark include worlds that no sane, good God would ever tolerate. The theories are very different, but each predicts the existence of worlds filled with horror and misery.

    Of course, plenty of thoughtful people argue that the Earth alone contains too much pain and suffering to be the work of a good God. But many others have disagreed, finding fairly nuanced things to say about what might justify God’s creation of a world that includes a planet like ours. For example, there is no forgiveness, courage, or fortitude without at least the perception of wrongs, danger, and difficulty. The most impressive human moral achievements seem to require such obstacles.

    Still, many horrifying things happen with nothing seemingly gained from them. And, Everett’s many-worlds and Tegmark’s modal realism both seem to imply that there are huge numbers of horrific universes inhabited solely by such unfortunates. Someone like myself, who remains attracted to the traditional picture of God as loving creator, is bound to find such consequences shocking, and will wonder just how strong the evidence is for these theories.

    Mathematical Multiverse: According to Tegmark, for every possible way in which mathematical models dictate that matter can be consistently arranged to fill a spacetime universe, there exists such a universe. platonicsolids.info

    The many-worlds interpretation arises from a problem in quantum mechanics. The Schrödinger equation, the fundamental law of quantum theory, is a description of the evolving states of particles. But some of the states it predicts are combinations—“superpositions”—of seemingly incompatible states, such as a coin landing both on heads and tails. We can wonder: What explains the fact that we don’t ever observe the combined incompatible states, but only observe coins that land on heads or tails? One answer many theorists provide is that there is more going on than the Schrödinger equation describes. They add a process called “the collapse of the wave function,” which results in a definite outcome of heads or tails.

    But in the 1950s, Everett proposed a bold alternative. His theory has no collapses, but instead holds that all the parts of these combined—or “superposed”—states occur as parts of equally real but relatively isolated worlds. There are some complete copies of the universe in which the coin lands heads, and in others tails. And this applies to all other physical states—not just flipping coins. There are some universes where you make the train and get to work on time, and others where you don’t, and so on. These slight differences create multiple overlapping universes, all branching off from some initial state in a great world-tree.

    Old-fashioned quantum theory assigns a tiny likelihood to things going really badly in the future. It also implies that, from any point in our actual past, things could have gone much worse than they actually did. Since the many worlds interpretation takes these possibilities as actual occurrences, it predicts that there are branching universes in which things do go as awfully as possible.

    For example, whenever there is a minute chance of a catastrophe that leaves all human beings utterly miserable but just barely healthy enough to reproduce, there is a branch in the world-tree in which this sorry state of affairs actually happens, generation after generation. So there are worlds in which the emergence of the human race proves to be an unmitigated tragedy—or so it seems.

    A religious Everettian might hope that God would just prune the tree, and leave only those branches where good triumphs over evil. But as the philosopher Jason Turner of the University of Arizona has pointed out, such pruning undermines the Schrödinger equation. If God prevents the worst universes from emerging on the world-tree, then the deterministic law would not truly describe the evolution of the multiverse. Not all the superposed states that it predicts would actually occur, but only those that God judges to be “good enough.”

    Even if the pruning argument doesn’t work, there is another reason to think that the many-worlds interpretation doesn’t pose a serious threat to belief in God. Everett’s multiverse is just a much expanded physical world like this one, and finding we were in it would be like finding we were in a world with many more inhabited planets, some the amplified versions of the worst parts of our planet and others the amplified versions of the best parts. And so, even the worst parts of an Everettian multiverse are just particularly ugly versions of planet Earth. If an afterlife helps to explain our seemingly pointless suffering, then it would help explain the seemingly pointless suffering in even the worst of these Everett worlds, if we suppose that everyone in every branch, shows up in an afterlife.

    A theist may also take comfort in the fact that the many-worlds interpretation is still far from scientific orthodoxy. Although beloved by Oxford philosophers and accepted by a growing number of theoretical physicists, the theory remains highly controversial, and there are fundamental problems still being hashed out by the experts.

    The Everettian multiverse contains worlds that are hard to reconcile with a good God, but Tegmark’s multiverse might contain the worst. His theory, from his 2014 book Our Mathematical Universe, isn’t anchored in quantum mechanics but in modal realism, the doctrine proposed by philosopher David Lewis that every possible way that things could have gone—every consistent, total history of a universe—is as real as our own universe.

    Most philosophers talk about possible worlds as abstract things, like numbers, located outside of space and time, and as if they are very different from the actual world, which is substantial and made out of good old-fashioned matter. Tegmark agrees that other merely possible universes are abstract like numbers. But he denies that this makes them less real than the physical world. He thinks our universe is itself fundamentally a mathematical structure. Every physicist agrees that there is a set of mathematical entities standing in relations that perfectly models the distribution of fields and particles which a perfect physics would ascribe to our world. But Tegmark argues that our universe is identical to those mathematical things.

    If the world we inhabit is a purely mathematical structure, then all the other possible worlds we can imagine are equally real, their existence a necessary result of slightly different mathematical structures. For every possible way in which mathematical models dictate that matter can be consistently arranged to fill a spacetime universe, there exists such a universe.

    These possible arrangements of matter are bound to include ones corresponding to miserable universes full of pointless suffering—universes like all of the worst branches in the Everettian world-tree, and infinitely many more just as bad. But there would also be worlds that are worse. Unlike Everett’s worlds that are generated by a physical theory, Tegmark’s worlds are generated by mere possibility, which he identifies with mathematical consistency.

    Budding Universes: Everett’s many worlds interpretation holds that there are multiple overlapping universes, all branching off from some initial state in a great world-tree. Jacopo Werther

    According to Tegmark, every possible story about living creatures that can be told by means of a mathematical model of the underlying physical facts is a true story. This means that even if some of Tegmark’s universes last long enough to include episodes in which their inhabitants have an afterlife, the existence of mathematical structures with every possible shape and size requires shorter worlds, too. And, infinitely many of these worlds will not last long enough for their inhabitants to enjoy an afterlife.

    There is one way, then, in which Everett’s multiverse poses less of a challenge to the theist than Tegmark’s. Everett’s theory doesn’t predict that God won’t do anything for people with short, miserable lives, and it doesn’t predict that God won’t somehow compensate them in an afterlife. Rather, it only predicts that there will be many more short, miserable lives than just the ones in our universe; whereas Tegmark’s theory implies that there have to be worlds in which there are short miserable lives and no afterlife.

    Adding insult to injury, since the horrifying worlds are consequences of pure mathematics, they exist as a matter of absolute necessity—so there is nothing God can do about it! The resulting picture will remain offensive to pious ears: A God who loved all creatures, but was forced to watch infinitely many of them endure lives of inconsolable suffering, would be a God embroiled in a tragedy.

    But there is still hope for the theist.

    Unlike the Everettian many worlds, which issue from experimental theories in physics and so are harder to dismiss, Tegmark’s theory is based on frail philosophical arguments. Take, for example, his claim that the physical universe is a purely mathematical structure: Why should we accept this? Ordinarily, physicists use mathematical structures as models for how the physical world might work, but they do not identify the mathematical model with the world itself. Tegmark’s reason for taking the latter approach is his conviction that physics must be purged of anything but mathematical terms. Non-mathematical concepts, he says, are “anthropocentric baggage,” and must be eliminated for objectivity’s sake. But why think that the only objective descriptions that can truly apply to things as they are in themselves are mathematical descriptions? So far as I can see, he never justifies this assumption. And such a counterintuitive starting point isn’t enough to threaten one’s belief in a benevolent God.

    Apart from the threats posed by the awful worlds within the multiverses of Everett and Tegmark, the idea that we inhabit a multiverse doesn’t have to undermine a belief in God. Every theist should take seriously the possibility that there might exist more universes, simply on the grounds that God would have reason to create more good stuff. Indeed, an infinitely ingenious, resourceful, and creative Being might be expected to work on canvases the size of worlds—some filled with frenetic activity, others more like vast minimalist paintings, many maybe even featuring intelligent beings like ourselves. And the theories of physicists such as Alan Guth and Andrei Linde—whose multiverse is an eternally inflating field that spins off baby universes—or Paul Steinhardt and Neil Turok—whose multiverse amounts to an endless cyclical universe punctuated by big bangs and big crunches—are arguably compatible with this theological vision.

    It may turn out that our world is fairly middling, one among the many universes that were good enough for God to create. And the idea of a multiverse consisting of disconnected spacetime universes may make it easier to believe that our world—our universe—is a part of a larger one that is on balance very good and created by a perfectly benevolent deity.

    Dean Zimmerman is a professor of philosophy at Rutgers University. Follow him on Twitter @deanwallyz.

    Rutgers smaller

    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 11:55 am on September 2, 2016 Permalink | Reply
    Tags: , , , Multiverse theory,   

    From New Scientist: “Stars burning strangely make life in the multiverse more likely” 


    New Scientist

    1 September 2016
    Jacob Aron

    The answer’s in the stars. NASA, ESA, and E. Sabbi (ESA/STScI)

    Your existence depends on an improbable threesome. A delicate reaction within stars called the triple-alpha process, which creates carbon, is often used to support the idea of the multiverse. Now, two researchers argue that stars in other universes might have alternative ways of producing carbon, giving life as we know it a greater chance in multiple universes.

    The triple-alpha process gets its name from the three helium nuclei involved, which are also known as alpha particles. When the universe formed, it mostly consisted of hydrogen and helium, the simplest elements in the periodic table. Heavier elements were forged by the first stars, which fused the lighter nuclei together.

    There’s just one problem with this tidy model. Fuse two alpha particles together and you end up with a nucleus of four protons and four neutrons – namely beryllium-8, an isotope of the fourth element in the periodic table. But beryllium-8 is highly unstable and falls apart into two alpha particles within a fraction of a second. That means there isn’t much of it in our universe.

    “The natural stepping stone towards bigger elements is not present,” says Fred Adams of the University of Michigan in Ann Arbor.

    That’s no way to build a cosmos – yet puzzlingly, here we are. In the 1950s, astronomer Fred Hoyle figured out a solution. He argued that the abundance of carbon in the universe must be the result of a coincidence between the energy levels of alpha particles and carbon-12.

    Hoyle said that because the energy of three alpha particles creates carbon-12 with more energy than it needs, this extra energy must be equal to an excited state of carbon-12, allowing it to decay to its ground state and remain stable. This so-called “resonance” between the energy values makes it possible to form carbon by fusing three alpha particles together.

    Experiments later proved him right, but the resonance introduced its own problems. It occurs at a very particular value, 7.644 megaelectronvolts (MeV), and calculations show that the triple-alpha reaction is very sensitive to this value. Vary it by 0.1 MeV and the reaction will slow, producing less carbon, and a change of more than 0.3 MeV will halt carbon production altogether.

    Hoyle and others argued that this means our universe must have been fine-tuned for life. That resonance could have occurred at a range of energies, and the fact that it just happened to occur at the point we needed it to for our existence makes us astonishingly lucky.

    The odds of this happening at random are very low, and some argue that the only way to explain it is if our universe is just one of many in a multiverse. In that case, each universe could have slightly different values for the fundamental constants of physics. Life would arise only in suitable universes, meaning we shouldn’t be surprised to find ourselves in one of these.

    Another kind of universe

    But now Adams and his colleague Evan Grohs have argued that if other universes have different fundamental constants anyway, it’s possible to create a universe in which beryllium-8 is stable, thus making it easy to form carbon and the heavier elements.

    For this to happen would require a change in the binding energy of beryllium-8 of less than 0.1 MeV – something that the pair’s calculations show should be possible by slightly altering the strength of the strong force, which is responsible for holding nuclei together.

    Simulating how stars might burn in such a universe, they found that the stable beryllium-8 would produce an abundance of carbon, meaning life as we know it could potentially arise. “There are many more working universes than most people realise,” says Adams.

    These universes would arguably be more logical, he says, with stars steadily building elements along the periodic table without having to resort to the triple-alpha process. “We tend to think not only is our universe fine-tuned for us, we also think this is the best universe one could design,” says Adams. “In some sense, we’ve designed a better universe.”

    “It’s an interesting point, that there is another way of treating the physics that is no bigger than the tweaking you need to get rid of the carbon resonance,” says Martin Rees of the University of Cambridge.

    But Rees points out that we don’t really know if the multiverse exists, let alone if different universes would have different physics. “We need a measure of the relative probability of all those things to decide whether we should be surprised that we’re in the universe we are in,” he says.

    See the full article here .

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  • richardmitnick 5:46 pm on May 9, 2016 Permalink | Reply
    Tags: , , Multiverse theory,   

    From Science Alert: “WATCH: What’s outside the Universe?” 


    Science Alert

    If the Universe is expanding, what’s it expanding into?

    22 APR 2016

    You’ve probably read about how the Universe is expanding, and has been expanding since the beginning of time. Over the course of 13.8 billion years or so, it’s stretched from the size of a billionth of a proton to the vast, unknowable expanse it is today.

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

    In fact, recent research suggests that it’s actually expanding faster than our current laws of physics can explain, and that’s kind of a problem.

    But all of that aside, whenever someone mentions our expanding Universe, we get a big, fat (turtle-surfing) elephant in the room. Because if the Universe is expanding, what exactly is it expanding into?

    As Fraser Cain from Universe Today explains, one possibility is that it’s expanding into an unfathomable cosmic void called the multiverse, which harbours not just our own Universe, but a multitude of parallel universes.

    Multiverse. Image credit: public domain, retrieved from https://pixabay.com/
    Multiverse. Image credit: public domain, retrieved from https://pixabay.com/

    We kinda want this to be the right answer, because if parallel universes really do exist, shit’s about to get so weird.

    As the video above explains, the laws of physics as we know them wouldn’t necessarily apply in other universes. Things are fundamental to us and everything we know, such as the pull of gravity or the binding strength of atoms, that simply would not exist in other universes.

    “For each one of these basic constants, it’s as if the laws of physics randomly rolled the dice, and came up with our Universe,” says Cain. “Maybe in another universe, the force of gravity is repulsive, or green, or spawns unicorns.”

    For a universe to form with the right combination of physical laws to allow for life to evolve, it’s a monkeys and typewriters situation – roll the dice an infinite number of times, and you’ll eventually get it right.

    So let’s say there are multiple universes – what if our Universe actually expanded so close to a neighbouring universe, it bumped into it?

    Turns out, signs of such a ‘cosmic bruise’ do exist, and scientists have been trying to explain them for decades. In fact, there’s one region in our Universe that’s so confounding, scientists have literally called it the Axis of Evil.

    According to Cain, there are a bunch of explanations that could explain the weirdness of the Axis of Evil more reliably than it being the site of a great ‘meeting of the universes’, but we can’t throw that possibility out just yet. And if it really is the case, what’s happening to the poor aliens living in the universe that we’re so rudely overlapping?

    I’ll let the video above handle that one, but let’s just say it’s somewhere between whatever the average of seven and green is, and the sum of 26 and unicorn dreams. Thanks a lot, science.

    See the full article here .

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