Category Archives: Quantum Physics
Theory of Everything? One of These Theories Could Explain the Very Nature of Our Universe… Maybe – Interesting Engineering
What if aliens showed up today? Not just any run-of-the-mill group of aliens either. We are talking about a group of highly intelligent creatures that have cracked all the mysteries our universe holds. These alleged aliens would know everything about the nature of reality. If they were to try to explain these ideas, do you think humans would be able to understand them? Better yet, would our leading ideas in science line up with what the aliens have to say? With our present-day understanding of the universe, how close would we be?
Most physicists would tell you that we are on the right path, but we still have some progress to make. In humanity's relentless pursuit to understand our reality, we have come up with testable and astoundingly accurate theories that explain events happening in an unimaginably small scale and an infinitely expansive universe. However, the current mathematical frameworks explaining the colossal and the minuscule do not agree with each other. For the past century, leading physicists have placed their hopes in the ever so elusive unified field theory or theory of everything (TOE). But, should they?
SEE ALSO: THE QUANTUM WORLD DOES NOT REALLY MAKE SENSE
In particle physics, a unified field theory, or grand unified theory, isan attempt to describe all fundamental forces and the relationships between elementary particles in terms of a single theoretical framework.
In the mid-19th century,James Clerk Maxwellformulated the first field theory in his theory ofelectromagnetism, which demonstrated the relationship between the forces of electricity and magnetism. Then, in the early 20th century,Albert Einsteindevelopedgeneral relativity, a field theory ofgravitation. Later, Einstein and others attempted to construct a unified field theory that incorporated both electromagnetism and gravity as different aspects of a single fundamental field.
Some researchers say that a unified theory is chasing a unicorn. Nevertheless, a vocal majority, including Einstein, believe it is possible to bridge the gap between the electromagnetic force, the strong and the weak nuclear forces, and gravity.
As the Cosmologist and particle physicistJohn Barrowof the University of Cambridge in the UK wrote, "Finding a theory of everything is quite conceivable. The laws of nature are rather few, they're simple and symmetrical, and there are only four fundamental forces." However, we are getting ahead of ourselves. You may be asking what exactly is a theory of everything?
The universe and everything in it are held together by four fundamental forces; the electromagnetic force, the strong and the weak nuclear force, and the gravity. The first three forces form the standard model of particle physics, which is the world of quantum mechanics in a nutshell. You are probably familiar with some aspects of the quantum world, like quantum entanglement and the uncertainty principle. Gravity is the black sheep of this family of forces, walking around like an unruly child, making things verydifficult for everyone.
The gravitational force explains the behavior of all things with mass or energy.In 1915, Albert Einstein proposed hisgeneral theory of relativity, which describes gravity not as aforce, but as a consequence of thecurvature of spacetimecaused by the uneven distribution of mass.
However, things (mostly math) fall apart when both quantum mechanics and relativity are applied together. A theory of everything would bring everything together, mathematically, and hopefully in a beautifully unified theory. However, this is immensely difficult. Although our understanding of physics has expanded since Einstein's contributions (i.e., strong and weak nuclear forces).
As the famed physicist once said to a student, "I want to know how God created this world. I'm not interested in this or that phenomenon, in the spectrum of this or that element. I want to know his thoughts; the rest are just details." So how much closer are we to knowing the mind of God? Well, it depends on who you ask. There are multiple candidates for a theory of everything, each with their own peculiarities, but each of them is equally mind-boggling. For this article, we will focus on the core ideas of these theories. Let's begin.
String theory is probably one of the strongest candidates on our list, as it is one of the most-explored potential theories of everything. You may have heard of it before in pop culture, or perhaps you have a friend who loves talking about it when drunk.
However, the world of string theory is a deep rabbit hole that can be a little brain-melting. String theory posits that particles are actually one-dimensional strings that vibrate at the very basic level.
According to String Theory, these strings vibrate at different levels determining particle types and properties, such as mass and charge. But, for this theory to work mathematically, extra spatial dimensions that cannot be experienced directly by humans need to be taken into the equation.
Though radical, the idea is an elegant approach to the conundrums mentioned above. However, there are multiple issues with string theory. We are going to focus on two big ones.
First and foremost, string theory is just that, "a theory," and theorists are having a hard time finding ways to properly test this idea, with some physicists going as far as to say that string theory is pseudoscience. This may change very soon. Leading physicists from institutions likeHarvard UniversityandStony Brook Universitybelieve the key to constructing a TOE over string theory revolves around the concept of inflation.
Inflation is thought to have played a major role in the Big Bang's earliest moments, explaining why the universe looks the way it does, and why it went through a phase of extreme expansion. If string theory can eventually be made to explain inflation, it may be one step closer to becoming the grand unified theory that we have been looking for all these years. However, this leads to our next issue.
At the moment, there are too many variants to the theory. Physicists have taken a shot at unifying multiple string theory ideas, creating a more general framework dubbed M-theory. However, M-theory just opens the doors to 10^ 500 universes. Some believe that this could be proof thatthere are multiple universes, or that the theory is untestable. String theory appears to have a long way to go before the scientific community can embrace it.
LQG or loop quantum gravity is currently one of string theory's biggest contesters for the title of "theory of everything". The general idea for loop quantum gravity is that space is not continuous but is broken up into tiny chunks or quantas: gravitational fields about 10^-35 meters across. These quantas of space are then connected by links to form the space that we experience. When these links get tangled into "braids" and "knots", they produce elementary particles. LQG has some bold claims, including describing how the universe may have formed after the collapse of a previous universe. Unlike string theory, LQG does not introduce extra dimensions and does not try to unify all forces. The theory could be used to explain some big real-world ideas and help clarifythe beginning of our universe.
However, most versions of loop quantum gravity struggle to incorporate gravity, and in fact, some don't even attempt to. Instead, they make an effort to quantize the gravitational field while it is kept separate from the other forces
This is the point on the list where things begin to get a bit weird, moving beyond mainstream science to more fringe areas of science or full-on thought experiments. Fotini Markopoulou and her colleagues at the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada aim to throw many universal assumptions out the window on their quest to find a theory of everything. Dubbed Quantum Graphity, Markopoulou believes that when the universe formed in the Big Bang, space did not exist as we know it.
According to this theory, the universe as we know it was once an abstract network of "nodes" of space. Each node was connected to one other. However, soon after the Big Bang, the universe collapsed, creating the principles that govern our reality today.
RESEARCHERS USE RICHARD FEYNMAN'S IDEAS TO DEVELOP A WORKING 'THEORY OF EVERYTHING'
One of the biggest issues with connecting gravity to the world of quantum mechanics is what happens to gravity on very small scales. Things get a little weird. The current models we have suggest that gravity is a very weak force. The same models would also have you believe that the closer two objects are to each other, the stronger the gravitational attraction between them. But this breaks down on the quantum level. Quantum Einstein gravity could be a potential explanation to this puzzle, and another candidate for a theory of everything. Proposed by Martin Reuter of the University of Mainz, Germany, this idea could open the doors to a quantum theory of gravity.
Garrett Lisi's paper "An Exceptionally Simple Theory of Everything" is controversial, elegant, and beautiful. According to the physicist's E8 theory, the 248-dimensional mathematical object above is the key to understanding the universe. The physicist and surfer's potential theory of everything can be summarized with an E8 Lie Group. Lisi created this structure by graphing the fundamental particles of a chart marking the electro-weak force, the hypercharge, and the charges in the Higgs field. After plotting all these particles on a 3D graph, this complex eight-dimensional mathematical pattern emerged with 248 points. Again, every single one of these dots are fundamental particles with different properties.
This is where things get interesting. There are a handful of particles on the diagram with specific properties that are "missing." This means that we can test and look for particles with these specific properties. Even more so, it is believed that these particles would correlate with gravity bridging our quantum and general relativity gap. Of course, this theory should be taken with a grain of salt, and even Lisi still believes the idea needs some work. However, he thinks it has a better chance of being a theory of everything than string theory. Shots fired.
As you have probably noticed, a lot of these theories float on the fringes of science. Even our most promising candidate string theory still struggles with finding practical ways of being tested. A grand unifying theory is based on the assumption that nature has an elegant, symmetrical mathematical solution to the principles that govern our reality. However, science shows us time and time again, that this is rarely the case. In an article for Nautilus, Sabine Hossenfelder, a Research Fellow at the Frankfurt Institute for Advanced Studies, the researcher stated that "This whole idea of a theory of everything is based on an unscientific premise."
"This is simply not a good strategy to develop scientific theories, and no, it is most certainly not standard methodology. Indeed, the opposite is the case. Relying on beauty in theory development has historically worked badly."
At times, the theory of everything seems to be as elusive as a shiny Pokemon and as mythical as a unicorn. Do you think one of the theories above will explain the nature of reality? Or do we still have a long way to go? What other ideas or approaches should we consider?
The rest is here:
Dr Katie Mack on how the Universe is going to end – BBC Focus Magazine
Sara Rigby: Could you give us a quick description of what your book is about, please?
Katie Mack: Yeah. My book is about the end of the universe. So in the book, I go through several different possibilities for how the universe might end and talk about how we are trying to figure that out in physics and astronomy and what it would look like if you were there to see it.
SR: Why does the universe have to end at all? Why can we not keep on as we are? It seems seems to be doing pretty well to me.
KM: Yeah. Yeah. Well, for a long time, though, there was an idea that maybe the universe could just be in a steady state and, you know, unchanging forever. But once the Big Bang was discovered, once it was found that the universe started out in this sort of hot, dense state and thats been expanding since then, it became clear that that the universe changes and evolves over time. And then the number of possibilities for its remaining sort of reasonably pleasant decreased rapidly now.
Now, its at the point where we can see that the universe is expanding and we can see that, in fact, the universe is expanding faster and faster all the time. And when you get to that point, its just the natural evolution is toward something where things that exist in the universe now will all be destroyed at some point in the future.
And there are a few different possibilities for how that can happen. But the idea that everythings just going to kind of keep going as as is does not does not work in the kind of universe we live in.
SR: We havent any idea of when this is going to happen. Id like to get this out of the way. Yeah. Is this something thats going to happen within a reasonable human timescale?
KM: Theres theres no theres no reasonable expectation that its something that wouldnt be in the very, very, very far distant future. So technically, theres a lot we dont understand about the universe and things could happen unexpectedly.
And in one of the one of the possible end of universe scenarios I talk about in the book, vacuum decay is based on a random process. But that in principle could happen at any time. But based on our understanding of how that physics works, we wouldnt expect it to occur anytime within the next ten to the power of one hundred years.
And even then, were not sure if its possible at all. So, you know, people do get worried about, you know, oh, it could happen in a moment. There are a lot of things that could technically happen in a moment that we dont worry about. And this one we very much should not worry about. For the most part, were talking about things that are so many trillions and trillions of years in the future that its its hard to even come up with words to explain that sort of timescale.
SR: Right. So if its not something that, you know, we even expect necessarily humans will even be around for. Why do you think its important to us to care about whats going to happen at the end of the universe?
KM: I dont know if its important that we care. But I think that we do. I think that its just part of human nature that we are interested in where we came from and were interested in where were going. And we use we in this case to mean that the bigger picture, that much larger universe.
But I think that were were interested in our our environment and in our story and in how we fit into the story of the cosmos and to the whole the whole narrative of of existence. And so its something that I think were just basically curious about. And there are reasons why, as a physicist, its an interesting thing to study because by extrapolating a theory to its ultimate conclusion to take stretching it to the limits you do. It does help you learn something about the theory about how the physics works.
Its a useful exercise to go through in any theory or model of the universe. So its a useful thing to do from a physics perspective to do these sort of thought experiments and to to extrapolate. But I think just as as people, we just we just want to know this stuff.
SR: And if so, there are in your book, you cover five different ways that the universe can end. Could you just give us a very, very brief outline of what those five different ways are?
KM: Sure, sure. So the first one I talk about is the big crunch. This is the idea that the current expansion of the universe might at some point reverse and everything could come crashing back together, creating conditions very much like the sort of hot, primordial soup we came out of initially. And that was unlikely. Now, based on our understanding of how the universe is expanding and speeding up in its expansion.
So that leads us to thats when the heat death, which is the one that we think is probably most likely if you talk to physicists and cosmologists, the heat death is it sounds counterintuitive to call it the heat death. Ill explain what that heat there refers to. But its also sometimes called the big freeze is where the universe continues expanding and expanding faster and faster indefinitely into the future.
And what that does is it kind of just dilutes everything and it makes galaxies move farther and farther apart from each other and everything gets more and more separated and isolated. And you end up with each galaxy sort of in its own sort of sphere of darkness where it cant see other galaxies. And and at some point, stars burn out and black holes evaporate and matter decays. And you just end up in this sort of cold, dark, empty, lonely universe.
And the only thing left in that universe is like a tiny amount of sort of waste heat from creation, sort of. All thats left is this this extremely low level radiation. Thats just the leftover leftover sort of detritus from from everything that ever was. And thats called the heat death.
And thats thats the saddest story. It does seem to be the kind of consensus model based on just extrapolating our current expansion into the future. And then the other the other three are sort of more speculative ideas that for various reasons people talk about in in the cosmology literature.
So one of them is called the big rip, where whatever is making the universe expand faster. Right now, we call that dark energy, depending on what kind of dark energy it is. It could be something that doesnt just separate galaxies apart and make them more isolated, but could actually pull the stars off of galaxies.
It could become more powerful over time and start disrupting structures in the universe sometime in the future. And it would pull galaxies apart, would pull planets away from their stars. And eventually, at the sort of final moments, it would destroy planets and stars and atoms and rip apart space itself.
And thats something that is not the most favourite idea. But its a its something that we cant rule out based on the data yet. But all we can say about it really is that we were fairly sure. Sure. It cant happen within the next two and a billion years or something like that. So, you know, as we get better data, well probably just push that number back and back. But we may not ever be able to say for certain that dark energy wont get weird at the end and destroy the universe that way.
And then the next one is called vacuum decay. And this is the one I mentioned that could technically happen at any moment. But again, dont worry about it. It almost certainly wont. Its where theres a sort of instability built into the universe.
And it means that the universes is vulnerable to a kind of quantum event occurring somewhere in space that would create a bubble of a different kind of space, that would expand through the universe at about the speed of light and destroy everything in its path. And thats a thats a fun one to me because it combines some interesting ideas in particle physics and cosmology.
And its just this very sudden, unexpected thing where at some moment the universe would basically just cease to exist. You know, there would just be this bubble. It would destroy everything that everythings done. So thats an interesting one. And my personal favourite, because its the most dramatic. And then the final the final one I talk about is really a set of different ideas that all have in common some kind of cycling cosmology.
So I call that the scenario bounce, but its really just some any kind of idea where you have an end of the universe. That then transitions to a new beginning and so on. Over and over again. Or even just previous ones. Maybe something that has. There was a previous universe before ours that led to our universe. Or at the end of our universe, there you new once some kind of idea like that.
And there are several possibilities for that. Somewhere you have kind of a big crunch that leads to a big bang. Somewhere you have. He does. That leads to a new big bang. So theres that theres a variety of ways you can get to that. But those ones are interesting because in principle, in certain models, you could have some information passing from the previous stage to the next one. And so it brings up a kind of way that something could live on past the end of the universe, which to many, is it an appealing idea?
SR: Wow. So theres a sort of rebirth of the universe in that sense?
KM:Yeah, yeah. I mean, it would be it would be a different universe, you know, and probably there would be no trace of anything of us. But the idea that there could be is is intriguing, I think, to a lot of people, including a lot of physicists.
SR: Right. So I sort of think if the big crunch, the big rip and the big bounces all being kind of related in a sense, which is right.
KM: In the sense that theyre all sort of based on the dramatic motions of the. Yes, it to me.
SR: So it sounds like they all are a result of the way that the universe is is expanding and moving at the minute. Yeah. So its like, well, you know, given that we know how were expanding in a minute, whats going to happen? Is it going to come back on itself? Is going to rip? Or is it going to say is that the mechanism which determine whether the universe, which sort of turned back on itself and into the big crunch or whether which, you know. Right.
KM: Yeah. So it all for the really for the heat death. And the big rip and the and the big crunch.
The thing thats governing the possible the possibility is there is dark energy. So, you know, we dont know what dark energy is. All we know is that as of about five billion years ago, the expansion of the universe was speeding up. And theres no theres nothing in sort of ordinary matter or energy that could do that. And so dark energy is is some component of the universe that makes space expand faster.
That sort of counteracts the gravity of everything thats kind of trying to pull matter in to pull space back in. And so we know because we dont know what dark energy is. We dont know for sure how its going to act in the future. Our sort of baseline assumption is that dark energy is just a cosmological constant. Its just a property of the cosmos. That space has this sort of stretching is built into it. And that leads you to a heat death where the universe expands faster and faster and just fades away eventually.
But if dark energy is something more dynamical, more interesting, that changes over time and some in some interesting way, then you could end up with something where dark energy gets more powerful and rips the universe part or changes nature, changes direction and pulls the universe back together. Maybe that could lead to some kind of bounce as well, although some of the bounce models have sort of extra components or extra things involved to make those stuff happen.
But yeah, so dark energy is the big kind of question in in trying to figure out whats going on with the future expansion of the universe. And then when it comes to vacuum decay, the big question there is trying to better understand particle physics and how that works in our universe, because thats what would break down and create this this change in in how, you know, the new kind of space would be a kind of space where particle physics acts differently. And thats that would be the the thing that would destroy everything.
SR: Basically, just like to go back to a dark energy for a moment. If thats the sort of mediating factor, the thing that we dont know enough about, how are we going about learning about the dark energy? And like, do we have any good theories about what it could be at the minute?
KM:Well, yeah. I mean, aside from a cosmological constant, theres the other ideas. The dark energy is whats called a scalar field, which is a kind of a kind of field that has some some value all throughout space.
Weve only we dont we will we only have evidence of scalar fields existing in physics in one other context. And thats the Higgs field thats associated with the Higgs boson, which is this particle that that the Large Hadron Collider discovered. It has something to do with how particles get mass. So a kind of stuff called a scalar field. Were pretty sure that those things can exist in in nature.
And if dark energy is something like that, then it could be something thats changing over time that does weird things to the universe. And and we also have reason to believe maybe there was a scalar field that was involved in the very early universe for for a very rapid expansion phase called inflation. So theres theres a theoretical construct for what what dark energy could be if its not just a property of space.
But as for figuring out, you know, the properties of dark energy, theres there arent that many possibilities to do that. Its actually quite hard to study because whether its a cosmological constant or a scalar field, its something that seems to be totally uniform throughout space. Invisible, untouchable. And all it does is make the universe expand faster. And so thats not an easy thing to study.
You cant capture that in the lab.
And so the the tools we have to study it are the expansion rate of the universe, which we study by looking at very, very distant objects, which were seeing as they were in the past, and see how theyre moving through the universe.
And then by looking at the how things like clusters of galaxies built up over time. By looking again deep into the past.
And those kinds of things allow us to to study the the effects the dark energy has had on the cosmos over time. And that gives us some clues as to how it works. There are also some possibilities that if it is some kind of new aspect of physics, like like a scalar field, there are certain versions of that that could interact with things in laboratories.
So there are some laboratory experiments that are looking for specific, specific kinds of dark energy or things associated with dark energy. So there are some laboratory possibilities, but it is a hard thing to study. And right now our best tools are things like galaxy surveys and there are some of those that are coming up that will help us to much better study the the evolution of the cosmos over time.
SR:So what do you look for in a Galaxy survey?
So you just you look at as many galaxies as you can find and you try and measure how theyre moving, how old they are, how far away they are and so on as a way to kind of trace out the expansion history of the universe. So theres a new instrument being built. The bureau, Rubin Observatory.
Its going to carry out a survey called the LSST, and that will be studying something like billions of galaxies through the universe. And its a survey of galaxies in the hopes that will the part of the sky that the telescope can see. And it will be it will be telling us a lot more about how just how matter is distributed through through our cosmos.
Then there are other tools we have, like studying the cosmic microwave background, which is the sort of afterglow of the big bang. And by looking at that, we can learn something about the early universe. We can learn something about the components of the universe. And that can also give us some more clues about dark energy and how its behaved over time as well.
SR:I think in your book, you described the cosmic microwave background as being a way to look directly at the Big Bang. Is that right?
KM: Yeah, yeah, yeah. So its its a its a wild thing. When we when we look out into the cosmos, when we look at very distant objects, were looking back in time because the light from those distant objects took a long time to get to us. So if we look at a galaxy thats billions of light years away, then it took the light billions of years to get to us. And if we look farther and farther away than we see parts of the universe that are so far away that it could take, you know, thirteen point eight billion years for the light to get to us the universe.
Thats how old the universe is. And so if we think that the universe started as this hot, dense sort of space filled with sort of roiling plasma, which is what which is sort of what the Big Bang Theory is built on, that the universe was hot and dense in its early times. But hot and dense everywhere.
It wasnt just a single point. It was the whole universe was hot, intense at some at some early time. Then it sends the reason that if we look anywhere in the universe, if we look far enough away, we will see parts of the universe that are so far in the past that they are still on fire.
From my perspective, theyre still in that hot, dense phase. And so we can actually look out into the cosmos and see that that primordial fire from which all of our cosmos was born and the light that we see in every direction, if we look for one of way, is this this leftover light from the big bang, the light directly coming from that fire to us travelling across billions of light years to come to us. Were seeing the final stages of that primordial fire when we look out into the coals. And I think thats I think thats amazing that we cant see that.
SR: And lets lets get back to the heat death of the universe. So how thats related to thermodynamics, isnt it? Yeah. Yeah.
KM: So, yeah, technically, you dont get to heat death until you get to the maximum entropy state of the cosmos. So entropy is a sort of measure of disorder. So the more disorder something is, the higher the entropy. Sotheres this very strict rule in physics called the second law of thermodynamics.
And what this says is that over time in any closed system and we think in the universe as well, the entropy can only increase. And this is why, you know, you cant have a perfectly efficient machine. You always lose a little bit of energy to to friction or something. You cant have an a perpetual motion machine because entropy increases. Theres always a little more disorder.
You always lose a little bit of energy to waste heat or something like that. And. So if thats the case in the universe, which it seems to be, then over time. All of the processes in the universe will be a little bit inefficient and things will degrade and decay and sort of fall apart. And so in the far, far, far future of the universe, you get closer and closer to the maximum entropy of the cosmos.
So you get to the point where entropy can no longer increase because everything is degraded. Everything is is dissipated into pure waste heat. All of the energy is disordered. And when you get to that point, when you have the maximum entropy state, then that is truly the heat death, because that means that basically nothing can happen anymore.
If if entropy has to increase, thats thats just a totally total solid law of physics that entropy can only increase. Then you cant get to maximum entropy and then do something that would create more entropy. So so at that point, you know, there can be little random fluctuations or something that might, you know, rearrange energy a little bit.
And then it would come back down to this. This magic moment, you say. But you cant you cant do anything productive. You cant build anything anymore. You cant even blink. You can you can do technical calculations that say you cant even think anymore.
Everything will be, you know, totally disordered.
SR: Is the heat death the same as saying that the universe will be the same temperature everywhere?
KM: Yeah, itll be itll be a uniform temperature. There might be, you know, random fluctuations here and there. That would settle out again. But, yeah, everything would be this this uniform temperature. And its and its a calculable temperature of kind of the background of the universe after after it reaches maximum entropy.
Its a very small number.
SR: So why is that the most likely explanation for whats going to happen to our universe?
Well, we think thats the most likely just because if you take the kind of expansion were having now where the universe is expanding and its speeding up in its expansion, then what that does is it kind of separates everything out and. And every sort of galaxy can only go through. So, you know, its own evolution with stars dying and things like that.
And then things will decay. And thats thats just part of its just kind of itll all sort of decay into entropy in its own space. And then once everything in each region decays, then all thats left is you basically you actually get a tiny, tiny bit of radiation from the cosmic horizon, which is sort of the.
A region around each point out to which that information cant pass anymore, but that theres a theres a kind of horizon that occurs in a space that thats expanding faster and faster all the time.
And that that kind of horizon has a little bit of radiation associated with it. And that that ends up being all thats left in the universe is just this tiny little bit of radiation thats basically, you know, just its just waste heat, more or less.
SR: All right. Thats something to look forward to.
KM:Yeah, its a bit of a its a bit of a sad, sad ending.
There are there are some interesting theories about how you could have random fluctuations that could lead to a new big bang or or even weird little entities fluctuating out of this this empty heat death universe.
So there are some interesting theories about about strange things that can happen if you just have a universe thats basically empty. But you leave it alone for an infinite amount of time. All the weird things can occur. And so in the book, I talk about some of the stranger hypotheses in there.
SR: So what can you give us an example?
KM: Yeah. So theres this theres this really weird sort of thought experiment thats been around for a while where if you think that if you want to have a universe that sort of where you you kind of randomly fluctuate out of a heat death universe and create a new big bang, if thats if thats an idea that you want for the origin of the cosmos, which which would make sense if you want a universe where you have an end of universe and the new beginnings here and there and branching out of some larger space, then the problem with that is that you can calculate that, that thats a very unlikely thing to happen, right.
To have that random fluctuation of a whole new universe. Its its its its very improbable. Much more probable is that only just like one galaxy would randomly fluctuate out of the sort of soup. And more more probable even than that. Its just one planet. Would would fluctuate out of it and then more probable than even that.
Just just one person or or even even more probable because it requires getting fewer particles together would be just a single brain, like a single human brain that thinks that its living in an entire universe with a whole past that had a big bang and in the cosmic evolution and everything like that. And this is actually this is actually a problem in physics that that that because that single human brain is more probable to occur than the entire universe.
You cant you cant say for sure that that we you know, we are not just imagining all of cosmic history. This is a fairly bizarre problem. Its called the Boltzmann brain problem. Right. And and its not that its not a problem because, you know, because you we actually think these these things would happen. But its a problem because its hard to figure out how these probabilities make sense.
If if you calculate that thats something more likely to happen than the universe, existing problems like that, and I know it is that we have to be we have to be really careful with how we how we suppose a universe might might come out of this kind of state. And. And you have to if you if you set up a system where where its more likely that were just imagining the cosmic history, then that that cosmic history actually existed, then youve probably set up a bad problem in physics.
And so its one of these things that physicists worry about when when constructing possible models of the universe.
SR: Now, lets talk a bit more about vacuum decay.You mentioned earlier that its the result of an instability in the universe, which brings about what you call in the book a quantum bubble of death. But I think thats what makes it my favourite theory.So what exactly is this instability?
KM: Right. So, OK, so I mentioned before the Higgs field, which is a kind of an energy field that pervades all of space. And the Higgs goes on. Is this particle that was discovered at the Large Hadron Collider that is somehow associated with this Higgs field?
Now, the Higgs boson was was called by some the God particle because because the Higgs field was associated with how particles got mass in the early universe. And so, you know, sort of the creation of of matter in some way has something to do with with the Higgs particle through the Higgs field.
But the Higgs field is really the important thing, not the particle itself. But because weve detected the particle, we can learn something about the Higgs field by measuring the mass of the particle and how it interacts with other particles and so on. And unfortunately, what we seem to be learning about the Higgs field is that it it looks like based on current data, it has a vulnerability to changing its value.
So the Higgs field, its this energy field that pervades all space. It has some value associated with it, some sort of number. And the value the Higgs field has determines how. Physics works how particles work together. The masses of the particles, which particles even exist, how the fields, how the forces of nature work together. And in the very early universe, the Higgs field had a different value and there were different mix of particles, different kinds of forces of nature. And.
And, you know, matter, atoms and molecules and things couldnt exist at that time because the laws of physics just werent set up that way. When the Higgs field changed to the value it has now, that allowed the creation of protons and neutrons, electrons and molecules and all of these things. Right. So if the Higgs field were to change again, that would be very bad for us as as creatures built out of atoms, molecules.
Because we we want our particles all together. We want physics to work the way it does. So unfortunately, the data currently point to the idea that theres that the current value of the Higgs field is not sort of the value that the universe would in some sense prefer that that there theres some other value that if you if you disturb the Higgs field enough, it would it would switch to that at that other value and be more stable.
There means that if you could somehow cause the Higgs field to change value at one point in space, then every point around it would also change value and would create a bubble of this kind of space with different laws of physics, different mix of particles and so on, that would then expand out at the speed of light and destroy everything because it would turn. It would put it into this this different kind of space.
This is called a true vacuum with different laws of physics. Now, fortunately, disturbing the Higgs field seems to be something that we cannot do, that even, you know, astrophysical events cannot do that. That doesnt seem to be plausible, but Im not sure wed want to either.
No, we wouldnt want to. But Im just saying, dont worry about particle colliders. They cant do this. Dont worry about that. About that.
But but one what can do that? What can switch the Higgs field to this other value? Is quantum tunnelling, which is a a process that happens all the time with with subatomic particles. We we we find quantum tunnelling in laboratories where a particle might be on one side of a barrier and then suddenly appear on the other side. And thats thats just something that happens in quantum mechanics.
And we we even use this in all our electronics and things like flash memory. We use it for certain kinds of microscopes. We make use of the fact that quantum tunnelling happens as a way to kind of slowly leak particles into into the machines and so on. Like there are quantum tunnelling is thing that totally happens all the time in in physics. And unfortunately, it could also happen to something like the Higgs field.
And if it did, if the Higgs field quantum tunnelled, its different to a different state, its somewhere in the cosmos, then that would also create this cascade, that would create this bubble, that would expand and destroy everything. And because quantum tunnelling is not something that we can deterministically predict, we cant say exactly when it will happen or where that means that its its just a random event that we we cant we cant say when or if it might occur, but we can put a timescale on it because there are sort of probabilities associated with that.
So we can say that its very, very unlikely to occur within the next ten to the power of one hundred years or maybe five hundred. So thats a long time, much longer than the age of the universe. We probably dont have to worry about it, but its intriguing because we dont know when it would happen if it if it were going to happen. We dont know for sure if it could happen, because the calculations that lead to the idea that the vacuum decay is even possible are based on assuming that we understand particle physics in all its detail.
And were we know that theres theres aspects of particle physics that we dont understand yet. So there might be something that comes into this picture and changes it entirely. But but its an intriguing possibility. And it is something that physicists worry about.
You know, how, how or what kinds of assumptions were making about. About particle physics and about cosmology.
Continued here:
Dr Katie Mack on how the Universe is going to end - BBC Focus Magazine
Quantum mechanics is immune to the butterfly effect – The Economist
That could help with the design of quantum computers
Aug 15th 2020
IN RAY BRADBURYs science-fiction story A Sound of Thunder, a character time-travels far into the past and inadvertently crushes a butterfly underfoot. The consequences of that minuscule change ripple through reality such that, upon the time-travellers return, the present has been dramatically changed.
The butterfly effect describes the high sensitivity of many systems to tiny changes in their starting conditions. But while it is a feature of classical physics, it has been unclear whether it also applies to quantum mechanics, which governs the interactions of tiny objects like atoms and fundamental particles. Bin Yan and Nikolai Sinitsyn, a pair of physicists at Los Alamos National Laboratory, decided to find out. As they report in Physical Review Letters, quantum-mechanical systems seem to be more resilient than classical ones. Strangely, they seem to have the capacity to repair damage done in the past as time unfolds.
To perform their experiment, Drs Yan and Sinitsyn ran simulations on a small quantum computer made by IBM. They constructed a simple quantum system consisting of qubitsthe quantum analogue of the familiar one-or-zero bits used by classical computers. Like an ordinary bit, a qubit can be either one or zero. But it can also exist in superposition, a chimerical mix of both states at once.
Having established the system, the authors prepared a particular qubit by setting its state to zero. That qubit was then allowed to interact with the others in a process called quantum scrambling which, in this case, mimics the effect of evolving a quantum system backwards in time. Once this virtual foray into the past was completed, the authors disturbed the chosen qubit, destroying its local information and its correlations with the other qubits. Finally, the authors performed a reversed scrambling process on the now-damaged system. This was analogous to running the quantum system all the way forwards in time to where it all began.
They then checked to see how similar the final state of the chosen qubit was to the zero-state it had been assigned at the beginning of the experiment. The classical butterfly effect suggests that the researchers meddling should have changed it quite drastically. In the event, the qubits original state had been almost entirely recovered. Its state was not quite zero, but it was, in quantum-mechanical terms, 98.3% of the way there, a difference that was deemed insignificant. The final output state after the forward evolution is essentially the same as the input state before backward evolution, says Dr Sinitsyn. It can be viewed as the same input state plus some small background noise. Oddest of all was the fact that the further back in simulated time the damage was done, the greater the rate of recoveryas if the quantum system was repairing itself with time.
The mechanism behind all this is known as entanglement. As quantum objects interact, their states become highly correlatedentangledin a way that serves to diffuse localised information about the state of one quantum object across the system as a whole. Damage to one part of the system does not destroy information in the same way as it would with a classical system. Instead of losing your work when your laptop crashes, having a highly entangled system is a bit like having back-ups stashed in every room of the house. Even though the information held in the disturbed qubit is lost, its links with the other qubits in the system can act to restore it.
The upshot is that the butterfly effect seems not to apply to quantum systems. Besides making life safe for tiny time-travellers, that may have implications for quantum computing, too, a field into which companies and countries are investing billions of dollars. We think of quantum systems, especially in quantum computing, as very fragile, says Natalia Ares, a physicist at the University of Oxford. That this result demonstrates that quantum systems can in fact be unexpectedly robust is an encouraging finding, and bodes well for potential future advances in the field.
This article appeared in the Science & technology section of the print edition under the headline "A flutter in time"
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Quantum mechanics is immune to the butterfly effect - The Economist
Major quantum computational breakthrough is shaking up physics and maths – The Conversation UK
MIP* = RE is not a typo. It is a groundbreaking discovery and the catchy title of a recent paper in the field of quantum complexity theory. Complexity theory is a zoo of complexity classes collections of computational problems of which MIP* and RE are but two.
The 165-page paper shows that these two classes are the same. That may seem like an insignificant detail in an abstract theory without any real-world application. But physicists and mathematicians are flocking to visit the zoo, even though they probably dont understand it all. Because it turns out the discovery has astonishing consequences for their own disciplines.
In 1936, Alan Turing showed that the Halting Problem algorithmically deciding whether a computer program halts or loops forever cannot be solved. Modern computer science was born. Its success made the impression that soon all practical problems would yield to the tremendous power of the computer.
But it soon became apparent that, while some problems can be solved algorithmically, the actual computation will last long after our Sun will have engulfed the computer performing the computation. Figuring out how to solve a problem algorithmically was not enough. It was vital to classify solutions by efficiency. Complexity theory classifies problems according to how hard it is to solve them. The hardness of a problem is measured in terms of how long the computation lasts.
RE stands for problems that can be solved by a computer. It is the zoo. Lets have a look at some subclasses.
The class P consists of problems which a known algorithm can solve quickly (technically, in polynomial time). For instance, multiplying two numbers belongs to P since long multiplication is an efficient algorithm to solve the problem. The problem of finding the prime factors of a number is not known to be in P; the problem can certainly be solved by a computer but no known algorithm can do so efficiently. A related problem, deciding if a given number is a prime, was in similar limbo until 2004 when an efficient algorithm showed that this problem is in P.
Another complexity class is NP. Imagine a maze. Is there a way out of this maze? is a yes/no question. If the answer is yes, then there is a simple way to convince us: simply give us the directions, well follow them, and well find the exit. If the answer is no, however, wed have to traverse the entire maze without ever finding a way out to be convinced.
Such yes/no problems for which, if the answer is yes, we can efficiently demonstrate that, belong to NP. Any solution to a problem serves to convince us of the answer, and so P is contained in NP. Surprisingly, a million dollar question is whether P=NP. Nobody knows.
The classes described so far represent problems faced by a normal computer. But computers are fundamentally changing quantum computers are being developed. But if a new type of computer comes along and claims to solve one of our problems, how can we trust it is correct?
Imagine an interaction between two entities, an interrogator and a prover. In a police interrogation, the prover may be a suspect attempting to prove their innocence. The interrogator must decide whether the prover is sufficiently convincing. There is an imbalance; knowledge-wise the interrogator is in an inferior position.
In complexity theory, the interrogator is the person, with limited computational power, trying to solve the problem. The prover is the new computer, which is assumed to have immense computational power. An interactive proof system is a protocol that the interrogator can use in order to determine, at least with high probability, whether the prover should be believed. By analogy, these are crimes that the police may not be able to solve, but at least innocents can convince the police of their innocence. This is the class IP.
If multiple provers can be interrogated, and the provers are not allowed to coordinate their answers (as is typically the case when the police interrogates multiple suspects), then we get to the class MIP. Such interrogations, via cross examining the provers responses, provide the interrogator with greater power, so MIP contains IP.
Quantum communication is a new form of communication carried out with qubits. Entanglement a quantum feature in which qubits are spookishly entangled, even if separated makes quantum communication fundamentally different to ordinary communication. Allowing the provers of MIP to share an entangled qubit leads to the class MIP*.
It seems obvious that communication between the provers can only serve to help the provers coordinate lies rather than assist the interrogator in discovering truth. For that reason, nobody expected that allowing more communication would make computational problems more reliable and solvable. Surprisingly, we now know that MIP* = RE. This means that quantum communication behaves wildly differently to normal communication.
In the 1970s, Alain Connes formulated what became known as the Connes Embedding Problem. Grossly simplified, this asked whether infinite matrices can be approximated by finite matrices. This new paper has now proved this isnt possible an important finding for pure mathematicians.
In 1993, meanwhile, Boris Tsirelson pinpointed a problem in physics now known as Tsirelsons Problem. This was about two different mathematical formalisms of a single situation in quantum mechanics to date an incredibly successful theory that explains the subatomic world. Being two different descriptions of the same phenomenon it was to be expected that the two formalisms were mathematically equivalent.
But the new paper now shows that they arent. Exactly how they can both still yield the same results and both describe the same physical reality is unknown, but it is why physicists are also suddenly taking an interest.
Time will tell what other unanswered scientific questions will yield to the study of complexity. Undoubtedly, MIP* = RE is a great leap forward.
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Major quantum computational breakthrough is shaking up physics and maths - The Conversation UK
6 new degrees approved, including graduate degrees in biostatistics and quantum information science: News at IU – IU Newsroom
The Indiana University Board of Trustees has approved six new degrees, four of which are graduate level.
All of the new graduate degrees are on the Bloomington campus:
Also approved were a Bachelor of Arts in theater, film and television at IUPUI and a Bachelor of Science in accounting at IU East.
The master's and doctoral degrees in biostatistics are offered by the Department of Epidemiology and Biostatistics in the School of Public Health-Bloomington. They will focus on rural public health issues and specialized areas in public health research, such as the opioid epidemic.
Biostatistics is considered a high-demand job field. Both degrees are intended to meet the labor market and educational and research needs of the state, which is trying to reduce negative health outcomes. Biostatisticians typically are hired by state and local health departments, federal government agencies, medical centers, medical device companies and pharmaceutical companies, among others.
The Master of Science in quantum information science will involve an intensive, one-year, multidisciplinary program with tracks that tie into physics, chemistry, mathematics, computer science, engineering and business. It's offered through the Office of Multidisciplinary Graduate Programs in the University Graduate School. The degree was proposed by the College of Arts and Sciences, the Luddy School of Informatics, Computing and Engineering, and the Kelley School of Business.
Most of the faculty who will teach the classes are members of the newly established IU Quantum Science and Engineering Center.
Students who earn the Master of Science in quantum information science can pursue careers with computer and software companies that are active with quantum computation, and national labs involved in quantum information science, among other opportunities.
The Master of International Affairs is a joint degree by the O'Neill School of Public and Environmental Affairs and the Hamilton-Lugar School of Global and International Studies. The degree is the first of its kind offered by any IU campus and meets student demand for professional master's programs having an international focus.
Featured components of the degree include the study of international relations and public administration. Graduates can expect to find employment in the federal government, such as the Department of State, the Department of Treasury or the U.S. intelligence community, or with private-sector firms in fields such as high-tech, global trade and finance.
The Bachelor of Arts in theater, film and television combines existing programs and provides them a more visible home in the School of Liberal Arts at IUPUI. The degree features three distinct concentrations:
Applied theater is a growing field that emphasizes and works with organizations around issues of social justice, social change, diversity and inclusion.
IU East's Bachelor of Science in accounting degree, offered through the School of Business and Economics, helps meet projected high demand in the accounting industry. It also will prepare students to take the certified public accountant or certified managerial accountant exams, or enter graduate programs in accounting or business.
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Students in the news | Announcements – Indiana Gazette
An Indiana native has been named a Fulbright Scholar.
The U.S. Department of State and the J. William Fulbright Foreign Scholarship Board have announced that Dr. Thomas E. Baker, who studies at University de Sherbrooke in Quebec, Canada, has received a Fulbright U.S. Scholar Program award to the United Kingdom.
Baker will research and provide mentorship at the University of York as part of a project to study the exact properties of density functional theory. Density functional theory was discovered in 1964 and has provided a way to simulate the quantum physics of large systems, especially to simulate materials. While density functional theory is proven to be exact, the theory requires approximations to use and approximations can give inaccurate results. Baker seeks to improve the theory by discovering more with modern methods from the broader field of condensed matter physics.
The son of John and Kathy Baker, of Indiana, he is a 2005 graduate of Indiana Area Senior High School.
The Fulbright program is the flagship international educational exchange program sponsored by the U.S. government and is designed to forge lasting connections between the people of the United States and the people of other countries, counter misunderstandings, and help people and nations work together toward common goals. The program was established in 1946.
The following Indiana County-area graduates were recognized as members of the class of 2020 of Edinboro University:
Julie E. Shirley, of Blairsville, who earned a Bachelor of Arts in criminal justice, with honors
Teresa A. Shields, of Clarksburg, who earned a Bachelor of Science in education middle level education, with honors
Makayla Dawn Murray, of Dayton, who earned a Master of Arts in communication studies
Nearly 1,200 students were named to the spring 2020 deans list at Edinboro University. The following Indiana County-area students are among them:
Ashleigh P. Bowman, of Indiana
Julie E. Shirley, of Blairsville
Rachael Duncan, of Blairsville
Teresa A Shields, of Clarksburg
Aubrie R. Putt, of Home
Matthew Anthony Wehrle, of Rossiter
Gabrielle M. LaBovick, of Saltsburg
In order to attain this academic honor, students must maintain a quality-point average of 3.4 or higher, complete a minimum of 12 semester hours of credit and receive no grade lower than a C in any course.
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A time traveler’s guide to the end of the universe – The Next Web
In this series well take a science and technology-based overhead view of the future from the perspective of a time traveler. This edition focuses on what youd see if you traveled far enough into the future to watch the universe end.
So youve decided to visit the end of the universe? Well, bully for you. Some folks might call it a spoiler, but I say we should skip to the end just to see where all of this is going.
Luckily for us Matt Caplan, a theoretical physicist from Illinois State University, recently conducted a study to determine how the end of the universe is likely to go down.
Ill save you some jargon: The universe ends not with a bang, kiss, or even a whimper, but with a Gothic rollicking finale.
As Caplan put it in his research paper:
In the far future long after star formation has ceased the universe will be populated by sparse degenerate remnants, mostly white dwarfs, though their ultimate fate is an open question. These white dwarfs will cool and freeze solid into black dwarfs while pycnonuclear fusion will slowly process their composition to iron-56.
However, due to the declining electron fraction the Chandrasekhar limit of these stars will be decreasing and will eventually be below that of the most massive black dwarfs. As such, isolated dwarf stars with masses greater than 1.2M will collapse in the far future due to the slow accumulation of iron-56 in their cores.
A long, long time from now (think of the number one followed by the word trillion a hundred times, thats how many years) the universes stars will all have either gone supernova or frozen. Those big enough to explode will shower the universe in light. Those too small to go supernova will slowly cool off until they reach ambient temperature.
Some of those cold stars will become a hypothetical kind of mass called a black dwarf. These dont exist yet but, as Michael Irving writes in New Atlas:
Its been calculated that this process would take trillions of years, and since the universe itself is only 13.4 billion years old, scientists dont expect any black dwarfs to exist yet. The oldest known white dwarfs are still shining brightly.
Irving continues:
A black dwarf was basically thought to be the end of the story, but according to Caplan, theres still some life to be found in these objects. Fusion can still occur at very cold temperatures it just takes an incredibly long time and requires some help from quantum mechanics.
In essence, these black dwarfs are just dead stars put out to pasture for eternity. If Caplans wrong about what happens next, the universe would end like The Sopranos did here, if you havent seen it and dont mind the spoiler.
But if Caplans right, it would mean that a small percentage of those dead black dwarf stars would come back to life just long enough to go supernova before everything goes quiet.
Heres how: quantum mechanics allows for weird stuff to happen that defies our laws of physics. Even though the black dwarfs are dead, they still contain all the necessary particles for quantum mechanics to work. Every once in a while, say over a few trillion years, a particle might tunnel (think teleportation) through other particles and have a tiny reaction.
[Read: Quantum physicists say time travelers dont have to worry about the butterfly effect]
Over trillions upon trillions of years these reactions could, as expert Vince Neil puts it kickstart the stars heart. Once the star rises from the dead it would then go supernova and produce the universes final interesting event: A muted Gothic ballet of tiny black supernovas.
Its impossible to know exactly what that would look like and, sadly, theres no guarantee youll get to see it happen no matter how far into the future you travel. By the time the black dwarfs are all thats left, the universe will be cold and dark. Those stars that come back to life will be spread out across what could potentially be an infinite blackness.
So dont be surprised if your trip to the end of the universe is a just a black screen. The good news is, if you wait around long enough you may just catch the next big bang.
Read next: EA renames its subscription service to EA Play
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A time traveler's guide to the end of the universe - The Next Web
Physicists watch quantum particles tunnel through solid barriers. Here’s what they found. – Space.com
The quantum world is a pretty wild one, where the seemingly impossible happens all the time: Teensy objects separated by miles are tied to one another, and particles can even be in two places at once. But one of the most perplexing quantum superpowers is the movement of particles through seemingly impenetrable barriers.
Now, a team of physicists has devised a simple way to measure the duration of this bizarre phenomenon, called quantum tunneling. And they figured out how long the tunneling takes from start to finish from the moment a particle enters the barrier, tunnels through and comes out the other side, they reported online July 22 in the journal Nature.
Quantum tunneling is a phenomenon where an atom or a subatomic particle can appear on the opposite side of a barrier that should be impossible for the particle to penetrate. It's as if you were walking and encountered a 10-foot-tall (3 meters) wall extending as far as the eye can see. Without a ladder or Spider-man climbing skills, the wall would make it impossible for you to continue.
Related: The 18 biggest unsolved mysteries in physics
However, in the quantum world, it is rare, but possible, for an atom or electron to simply "appear" on the other side, as if a tunnel had been dug through the wall. "Quantum tunneling is one of the most puzzling of quantum phenomena," said study co-author Aephraim Steinberg, co-director of the Quantum Information Science Program at Canadian Institute for Advanced Research. "And it is fantastic that we're now able to actually study it in this way."
Quantum tunneling is not new to physicists. It forms the basis of many modern technologies such as electronic chips, called tunnel diodes, which allow for the movement of electricity through a circuit in one direction but not the other. Scanning tunneling microscopes (STM) also use tunneling to literally show individual atoms on the surface of a solid. Shortly after the first STM was invented, researchers at IBM reported using the device to spell out the letters IBM using 35 xenon atoms on a nickel substrate.
While the laws of quantum mechanics allow for quantum tunneling, researchers still don't know exactly what happens while a subatomic particle is undergoing the tunneling process. Indeed, some researchers thought that the particle appears instantaneously on the other side of the barrier as if it instantaneously teleported there, Sci-News.com reported.
Researchers had previously tried to measure the amount of time it takes for tunneling to occur, with varying results. One of the difficulties in earlier versions of this type of experiment is identifying the moment tunneling starts and stops. To simplify the methodology, the researchers used magnets to create a new kind of "clock" that would tick only while the particle was tunneling.
Subatomic particles all have magnetic properties and when magnets are in an external magnetic field, they rotate like a spinning top. The amount of rotation (also called precession) depends on how long the particle is bathed in that magnetic field. Knowing that, the Toronto group used a magnetic field to form their barrier. When particles are inside the barrier, they precess. Outside it, they don't. So measuring how long the particles precess told the researchers how long those atoms took to tunnel through the barrier.
Related: 18 times quantum particles blew our minds
"The experiment is a breathtaking technical achievement," said Drew Alton, physics professor at Augustana University, in South Dakota.
The researchers prepared approximately 8,000 rubidium atoms, cooled them to a billionth of a degree above absolute zero. The atoms needed to be this temperature, otherwise they would have moved around randomly at high speeds, rather than staying in a small clump. The scientists used a laser to create the magnetic barrier; they focused the laser so that the barrier was 1.3 micrometers (microns) thick, or the thickness of about 2,500 rubidium atoms. (So if you were a foot thick, front to back, this barrier would be the equivalent of about half a mile thick.) Using another laser, the scientists nudged the rubidium atoms toward the barrier, moving them about 0.15 inches per second (4 millimeters/s).
As expected, most of the rubidium atoms bounced off the barrier. However, due to quantum tunneling, about 3% of the atoms penetrated the barrier and appeared on the other side. Based on the precession of those atoms, it took them about 0.6 milliseconds to traverse the barrier.
Chad Orzel, an associate professor of physics at Union College in New York, who was not part of the study, applauded the experiment, "Their experiment is ingeniously constructed to make it difficult to interpret as anything other than what they say," said Orzel, author of "How to Teach Quantum Mechanics to Your Dog" (Scribner, 2010) It "is one of the best examples you'll see of a thought experiment made real," he added.
Experiments exploring quantum tunneling are difficult and further research is needed to understand the implications of this study. The Toronto group is already considering improvements to their apparatus to not only determine the duration of the tunneling process, but to also see if they can learn anything about velocity of the atoms at different points inside the barrier. "We're working on a new measurement where we make the barrier thicker and then determine the amount of precession at different depths," Steinberg said. "It will be very interesting to see if the atoms' speed is constant or not."
In many interpretations of quantum mechanics, it is impossible even in principle to determine a subatomic particle's trajectory. Such a measurement could lead to insights into the confusing world of quantum theory. The quantum world is very different from the world we're familiar with. Experiments like these will help make it a little less mysterious.
Originally published on Live Science.
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This is the way the universe ends: not with a whimper, but a bang – Science Magazine
An artists impression of a black dwarf, a cooled-down stellar remnant that could form in trillions of years
By Adam MannAug. 11, 2020 , 5:35 PM
In the unimaginably far future, cold stellar remnants known as black dwarfs will begin to explode in a spectacular series of supernovae, providing the final fireworks of all time. Thats the conclusion of a new study, which posits that the universe will experience one last hurrah before everything goes dark forever.
Astronomers have long contemplated the ultimate end of the cosmos. The known laws of physics suggest that by about 10100 (the No. 1 followed by 100 zeros) years from now, star birth will cease, galaxies will go dark, and even black holes will evaporate through a process known as Hawking radiation, leaving little more than simple subatomic particles and energy. The expansion of space will cool that energy nearly to 0 kelvin, or absolute zero, signaling the heat death of the universe and total entropy.
But while teaching an astrophysics class this spring, theoretical physicist Matt Caplan of Illinois State University realized the fate of one last group of entities had never been accounted for. After exhausting their thermonuclear fuel, low mass stars like the Sun dont pop off in dramatic supernovae; rather, they slowly shed their outer layers and leave behind a scorching Earth-size core known as a white dwarf.
They are essentially pans that have been taken off the stove, Caplan says. Theyre going to cool and cool and cool, basically forever.
White dwarfs crushing gravitational weight is counterbalanced by a force called electron degeneracy pressure. Squeeze electrons together, and the laws of quantum mechanics prevent them from occupying the same state, allowing them to push back and hold up the remnants mass.
The particles in a white dwarf stay locked in a crystalline lattice that radiates heat for trillions of years, far longer than the current age of the universe. But eventually, these relics cool off and become a black dwarf.
Because black dwarfs lack energy to drive nuclear reactions, little happens inside them. Fusion requires charged atomic nuclei to overcome a powerful electrostatic repulsion and merge. Yet over long time periods, quantum mechanics allows particles to tunnel through energetic barriers, meaningfusion can still occur, albeit at extremely low rates.
When atoms such as silicon and nickel fuse toward iron, they produce positrons, the antiparticle of an electron. These positrons would ever-so-slowly destroy some of the electrons in a black dwarfs center and weaken its degeneracy pressure. For stars between roughly 1.2 and 1.4 times the Suns massabout 1% of all stars in the universe todaythis weakening would eventually result in a catastrophic gravitational collapse that drives a colossal explosion similar to the supernovae of higher mass stars, Caplan reports this month in the Monthly Notices of the Royal Astronomical Society.
Caplan says the dramatic detonations will begin to occurabout 101100 years from now, a number the human brain can scarcely comprehend. The already unfathomable number 10100 is known as a googol, so 101100 would be a googol googol googol googol googol googol googol googol googol googol googol years. The explosions would continue until 1032000 years from now, which would require most of a magazine page to represent in a similar fashion.
A time traveler hoping to witness this last cosmic display would be disappointed. By the start of this era, the mysterious substance acting in opposition to gravity called dark energy will have driven everything in the universe apart so much that each individual black dwarf would be surrounded by vast darkness: The supernovae would even be unobservable to each another.
In fact, Caplan showed that the radius of the observable universe will have by then grown by about e10^1100 (where e is approximately 2.72), a figure immensely larger than either of those given above. This is the biggest number Im ever going to have to seriously work with in my career, he says.
Gregory Laughlin, an astrophysicist at Yale University, praises the research as a fun thought experiment. The value of contemplating these mind-boggling timescales is that they allow scientists to consider physical processes that havent had enough time to unfold in the current era, he says.
Still, I think its important to stress that any investigations of the far future are necessarily tongue in cheek, Laughlin says. Our view of the extremely distant future is a reflection of our current understanding, and that view will change from one year to the next.
For example, some of the grand unified theories of physics suggest the proton eventually will decay. This would dissolve Caplans black dwarfs long before they would explode. And some cosmological models have hypothesized that the universe could collapse back in on itself in a big crunch, precluding the final light show.
Caplan himself enjoys peering into the distant future. I think our awareness of our own mortality definitely motivates some fascination with the end of the universe, he says. You can always reassure yourself, when things go wrong, that it wont matter once entropy is maximized.
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This is the way the universe ends: not with a whimper, but a bang - Science Magazine
Quantum Computing for the Next Generation of Computer Scientists and Researchers – Campus Technology
C-Level View | Feature
A Q&A with Travis Humble
Travis Humble is a distinguished scientist and director of the Quantum Computing Institute at Oak Ridge National Laboratory. The institute is a lab-wide organization that brings together all of ORNL's capabilities to address the development of quantum computers. Humble is also an academic, holding a joint faculty appointment at the University of Tennessee, where he is an assistant professor with the Bredesen Center for Interdisciplinary Research and Graduate Education. In the following Q&A, Humble gives CT his unique perspectives on the advancement of quantum computing and its entry into higher education curricula and research.
"It's an exciting area that's largely understaffed. There are far more opportunities than there are people currently qualified to approach quantum computing." Travis Humble
Mary Grush: Working at the Oak Ridge National Laboratory as a scientist and at the University of Tennessee as an academic, you are in a remarkable position to watch both the development of the field of quantum computing and its growing importance in higher education curricula and research. First, let me ask about your role at the Bredesen Center for Interdisciplinary Research and Graduate Education. The Bredesen Center draws on resources from both ORNL and UT. Does the center help move quantum computing into the realm of higher education?
Travis Humble: Yes. The point of the Bredesen Center is to do interdisciplinary research, to educate graduate students, and to address the interfaces and frontiers of science that don't fall within the conventional departments.
For me, those objectives are strongly related to my role at the laboratory, where I am a scientist working in quantum information. And the joint work ORNL and UT do in quantum computing is training the next generation of the workforce that's going to be able to take advantage of the tools and research that we're developing at the laboratory.
Grush: Are ORNL and UT connected to bring students to the national lab to experience quantum computing?
Humble: They are so tightly connected that it works very well for us to have graduate students onsite performing research in these topics, while at the same time advancing their education through the university.
Grush: How does ORNL's Quantum Computing Institute, where you are director, promote quantum computing?
Humble: As part of my work with the Quantum Computing Institute, I manage research portfolios and direct resources towards our most critical needs at the moment. But I also use that responsibility as a gateway to get people involved with quantum computing: It's an exciting area that's largely understaffed. There are far more opportunities than there are people currently qualified to approach quantum computing.
The institute is a kind of storefront through which people from many different areas of science and engineering can become involved in quantum computing. It is there to help them get involved.
Grush: Let's get a bit of perspective on quantum computing why is it important?
Humble: Quantum computing is a new approach to the ways we could build computers and solve problems. This approach uses quantum mechanics that support the most fundamental theories of physics. We've had a lot of success in understanding quantum mechanics it's the technology that lasers, transistors, and a lot of things that we rely on today were built on.
But it turns out there's a lot of untapped potential there: We could take further advantage of some of the features of quantum physics, by building new types of technologies.
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Quantum Computing for the Next Generation of Computer Scientists and Researchers - Campus Technology