Category Archives: Quantum Physics

Subatomic particles can be linked to each other even if separated by billions of light-years of space.

But this strange and spooky phenomenon hadnt been proven until Walnut Creek-based physicist John Clauser performed a pioneering experiment at UC-Berkeley in 1972 an accomplishment that on Tuesday was honored with the Nobel Prize in Physics.

Clauser, 79, shares the $900,000 prize with two fellow physicists who followed in his footsteps: Alain Aspect of Universit Paris-Saclay and cole Polytechnique in France, and Anton Zeilinger, of the University of Vienna in Austria.

This discovery, now a core concept of quantum mechanics, could revolutionize computing, cryptography and the transfer of information via what is known as quantum teleportation, according to the Nobel committee.

Working independently, the three scientists conducted experiments that demonstrated quantum entanglement, an odd phenomenon in which one particle can instantaneously influence the behavior of other particles even if they are far away, such as at opposite sides of the universe.

Clausers work measured the behavior of pairs of tiny photons, which were entangled, or acting in concert. It showed, in essence, that nature is capable of sending signals faster than the speed of light.

This phenomenon, the foundation of todays quantum computers and other modern quantum technologies, is so weird that physicist Albert Einstein called it spooky action at a distance.

Today we honor three physicists whose pioneering experiments showed us that the strange quantum world of entanglement is not just the microworld of atoms, and certainly not a virtual world of mysticism or science fiction, but the real world we live in, said Thors Hans Hansson of the Nobel Committee for Physics during a news conference in Stockholm.

Clauser, now retired, spends his days racing his 40-foot yacht Bodacious in San Francisco Bay, the greatest place in the world for sailing.

In an interview Tuesday, he told the Bay Area News Grouphe was thrilled by the 3 a.m. news from Stockholm and the tsunami of congratulatory calls. It took me over an hour to get my pants on, he joked.

Clauser, born a year after Pearl Harbor in 1942, grew up in the suburbs of Baltimore where his father had been hired to create Johns Hopkins Universitys aeronautics department.

He credits his father with his love of electronic tinkering, an essential skill for future experimental discoveries.

After school, when he was supposed to be doing homework, mostly what I would do is just sort of wander around the lab and gawk at all of the nifty laboratory equipment, he said in an oral history recorded by the American Physics Institute.

My dad was absolutely a marvelous teacher, my whole formative years, he recalled. Every time I asked a question, he knew the answer and would answer it in gory detail so that I would understand it. I mean, he didnt force feed me, but he did it in such a way that I continuously hungered for more.

Clauser first came to California in the early 1960s to study physics at the California Institute of Technology, then earned his PhD at Columbia University.

The study of Advanced Quantum Mechanics a field he would later revolutionize initially daunted him. He didnt understand its mathematical manipulations, and repeated the class three times before earning the requisite B grade.

I just didnt really believe it all. I was convinced that there were things that were wrong, he said. My Dad had always taught me, Son, look at the data. People will have lots of fancy theories, but always go back to the original data and see if you come to the same conclusions. Whenever I do that, I come up with very different conclusions.

That skepticism paved the way for his future Nobel. While working at UC Berkeley, he stumbled upon a fascinating theory by Northern Irish physicist John Stewart Bell, which explored what entanglements spooky action said about photons behavior and the fundamental nature of reality.

But wheres the experimental evidence? Clauser wondered. He knew Bells theorem could be tested.

He told PBSs Nova how he rummaged around the hidden storage rooms of Lawrence Berkeley National Laboratory, scavenging for old equipment to design the experiments he needed.

There are two kinds of people, really. Those who kind of like to use old junk and/or build it themselves from scratch. And those who go out and buy shiny new boxes, he said. Ive gotten pretty good at dumpster diving.

He faced criticism from many fellow physicists. Everybody told me I was crazy, and I was going ruin my career by wasting his time on such a philosophical question, he recalled.

In an experiment in the sub-basement of UC Berkeleys Birge Hall, conducted alongside the late fundamental physicist Stuart Freedman, he measured quantum entanglement by firing thousands of photons in opposite directions. They showed that the photons could act in concert despite being physically separated.

The experimentwas so novel that it was completely underappreciated at the time, said Berkeley Lab Director Mike Witherell. It was 10 years before physicists started to realize how quantum entanglement could be exploited. That was when the next decisive experiments were done, leading to the new quantum era we are now experiencing.

Unable to find a job as a professor, Clauser moved to Lawrence Livermore National Laboratory to do controlled fusion plasma physics experiments but later left because he refused to do classified work.

His insights are now the scientific underpinning for todays efforts to develop quantum cryptography, a method of encryption that uses the properties of quantum mechanics to secure and transmit data in a way that cannot be hacked.

Such powerful commercial applications were inconceivable at the time, he said.

I was totally unaware of how much money and interest there was in cryptography, he said. Heck, most of my computers didnt even require passwords. The only reason I have them on now is because we have all of the ones in the house all networked, and you cant put it on a network without putting passwords on them.

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Bay Area physicist and quantum physics pioneer wins Nobel Prize

A mind-bending, jargon-free account of the popular interpretation of quantum mechanics.

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Quantum physics is strange. At least, it is strange to us, because the rules of the quantum world, which govern the way the world works at the level of atoms and subatomic particles (the behavior of light and matter, as the renowned physicist Richard Feynman put it), are not the rules that we are familiar with the rules of what we call common sense.

The quantum rules, which were mostly established by the end of the 1920s, seem to be telling us that a cat can be both alive and dead at the same time, while a particle can be in two places at once. But to the great distress of many physicists, let alone ordinary mortals, nobody (then or since) has been able to come up with a common-sense explanation of what is going on. More thoughtful physicists have sought solace in other ways, to be sure, namely coming up with a variety of more or less desperate remedies to explain what is going on in the quantum world.

These remedies, the quanta of solace, are called interpretations. At the level of the equations, none of these interpretations is better than any other, although the interpreters and their followers will each tell you that their own favored interpretation is the one true faith, and all those who follow other faiths are heretics. On the other hand, none of the interpretations is worse than any of the others, mathematically speaking. Most probably, this means that we are missing something. One day, a glorious new description of the world may be discovered that makes all the same predictions as present-day quantum theory, but also makes sense. Well, at least we can hope.

Meanwhile, I thought I might provide an agnostic overview of one of the more colorful of the hypotheses, the many-worlds, or multiple universes, theory. For overviews of the other five leading interpretations, I point you to my book, Six Impossible Things. I think youll find that all of them are crazy, compared with common sense, and some are more crazy than others. But in this world, crazy does not necessarily mean wrong, and being more crazy does not necessarily mean more wrong.

If you have heard of the Many Worlds Interpretation (MWI), the chances are you think that it was invented by the American Hugh Everett in the mid-1950s. In a way thats true. He did come up with the idea all by himself. But he was unaware that essentially the same idea had occurred to Erwin Schrdinger half a decade earlier. Everetts version is more mathematical, Schrdingers more philosophical, but the essential point is that both of them were motivated by a wish to get rid of the idea of the collapse of the wave function, and both of them succeeded.

As Schrdinger used to point out to anyone who would listen, there is nothing in the equations (including his famous wave equation) about collapse. That was something that Bohr bolted on to the theory to explain why we only see one outcome of an experiment a dead cat or a live cat not a mixture, a superposition of states. But because we only detect one outcome one solution to the wave function that need not mean that the alternative solutions do not exist. In a paper he published in 1952, Schrdinger pointed out the ridiculousness of expecting a quantum superposition to collapse just because we look at it. It was, he wrote, patently absurd that the wave function should be controlled in two entirely different ways, at times by the wave equation, but occasionally by direct interference of the observer, not controlled by the wave equation.

Although Schrdinger himself did not apply his idea to the famous cat, it neatly resolves that puzzle. Updating his terminology, there are two parallel universes, or worlds, in one of which the cat lives, and in one of which it dies. When the box is opened in one universe, a dead cat is revealed. In the other universe, there is a live cat. But there always were two worlds that had been identical to one another until the moment when the diabolical device determined the fate of the cat(s). There is no collapse of the wave function. Schrdinger anticipated the reaction of his colleagues in a talk he gave in Dublin, where he was then based, in 1952. After stressing that when his eponymous equation seems to describe different possibilities (they are not alternatives but all really happen simultaneously), he said:

Nearly every result [the quantum theorist] pronounces is about the probability of this or that or that happening with usually a great many alternatives. The idea that they may not be alternatives but all really happen simultaneously seems lunatic to him, just impossible. He thinks that if the laws of nature took this form for, let me say, a quarter of an hour, we should find our surroundings rapidly turning into a quagmire, or sort of a featureless jelly or plasma, all contours becoming blurred, we ourselves probably becoming jelly fish. It is strange that he should believe this. For I understand he grants that unobserved nature does behave this waynamely according to the wave equation. The aforesaid alternatives come into play only when we make an observation which need, of course, not be a scientific observation. Still it would seem that, according to the quantum theorist, nature is prevented from rapid jellification only by our perceiving or observing it it is a strange decision.

In fact, nobody responded to Schrdingers idea. It was ignored and forgotten, regarded as impossible. So Everett developed his own version of the MWI entirely independently, only for it to be almost as completely ignored. But it was Everett who introduced the idea of the Universe splitting into different versions of itself when faced with quantum choices, muddying the waters for decades.

It was Hugh Everett who introduced the idea of the Universe splitting into different versions of itself when faced with quantum choices, muddying the waters for decades.

Everett came up with the idea in 1955, when he was a PhD student at Princeton. In the original version of his idea, developed in a draft of his thesis, which was not published at the time, he compared the situation with an amoeba that splits into two daughter cells. If amoebas had brains, each daughter would remember an identical history up until the point of splitting, then have its own personal memories. In the familiar cat analogy, we have one universe, and one cat, before the diabolical device is triggered, then two universes, each with its own cat, and so on. Everetts PhD supervisor, John Wheeler, encouraged him to develop a mathematical description of his idea for his thesis, and for a paper published in the Reviews of Modern Physics in 1957, but along the way, the amoeba analogy was dropped and did not appear in print until later. But Everett did point out that since no observer would ever be aware of the existence of the other worlds, to claim that they cannot be there because we cannot see them is no more valid than claiming that the Earth cannot be orbiting around the Sun because we cannot feel the movement.

Everett himself never promoted the idea of the MWI. Even before he completed his PhD, he had accepted the offer of a job at the Pentagon working in the Weapons Systems Evaluation Group on the application of mathematical techniques (the innocently titled game theory) to secret Cold War problems (some of his work was so secret that it is still classified) and essentially disappeared from the academic radar. It wasnt until the late 1960s that the idea gained some momentum when it was taken up and enthusiastically promoted by Bryce DeWitt, of the University of North Carolina, who wrote: every quantum transition taking place in every star, in every galaxy, in every remote corner of the universe is splitting our local world on Earth into myriad copies of itself. This became too much for Wheeler, who backtracked from his original endorsement of the MWI, and in the 1970s, said: I have reluctantly had to give up my support of that point of view in the end because I am afraid it carries too great a load of metaphysical baggage. Ironically, just at that moment, the idea was being revived and transformed through applications in cosmology and quantum computing.

Every quantum transition taking place in every star, in every galaxy, in every remote corner of the universe is splitting our local world on Earth into myriad copies of itself.

The power of the interpretation began to be appreciated even by people reluctant to endorse it fully. John Bell noted that persons of course multiply with the world, and those in any particular branch would experience only what happens in that branch, and grudgingly admitted that there might be something in it:

The many worlds interpretation seems to me an extravagant, and above all an extravagantly vague, hypothesis. I could almost dismiss it as silly. And yet It may have something distinctive to say in connection with the Einstein Podolsky Rosen puzzle, and it would be worthwhile, I think, to formulate some precise version of it to see if this is really so. And the existence of all possible worlds may make us more comfortable about the existence of our own world which seems to be in some ways a highly improbable one.

The precise version of the MWI came from David Deutsch, in Oxford, and in effect put Schrdingers version of the idea on a secure footing, although when he formulated his interpretation, Deutsch was unaware of Schrdingers version. Deutsch worked with DeWitt in the 1970s, and in 1977, he met Everett at a conference organized by DeWitt the only time Everett ever presented his ideas to a large audience. Convinced that the MWI was the right way to understand the quantum world, Deutsch became a pioneer in the field of quantum computing, not through any interest in computers as such, but because of his belief that the existence of a working quantum computer would prove the reality of the MWI.

This is where we get back to a version of Schrdingers idea. In the Everett version of the cat puzzle, there is a single cat up to the point where the device is triggered. Then the entire Universe splits in two. Similarly, as DeWitt pointed out, an electron in a distant galaxy confronted with a choice of two (or more) quantum paths causes the entire Universe, including ourselves, to split. In the DeutschSchrdinger version, there is an infinite variety of universes (a Multiverse) corresponding to all possible solutions to the quantum wave function. As far as the cat experiment is concerned, there are many identical universes in which identical experimenters construct identical diabolical devices. These universes are identical up to the point where the device is triggered. Then, in some universes the cat dies, in some it lives, and the subsequent histories are correspondingly different. But the parallel worlds can never communicate with one another. Or can they?

Deutsch argues that when two or more previously identical universes are forced by quantum processes to become distinct, as in the experiment with two holes, there is a temporary interference between the universes, which becomes suppressed as they evolve. It is this interaction that causes the observed results of those experiments. His dream is to see the construction of an intelligent quantum machine a computer that would monitor some quantum phenomenon involving interference going on within its brain. Using a rather subtle argument, Deutsch claims that an intelligent quantum computer would be able to remember the experience of temporarily existing in parallel realities. This is far from being a practical experiment. But Deutsch also has a much simpler proof of the existence of the Multiverse.

What makes a quantum computer qualitatively different from a conventional computer is that the switches inside it exist in a superposition of states. A conventional computer is built up from a collection of switches (units in electrical circuits) that can be either on or off, corresponding to the digits 1 or 0. This makes it possible to carry out calculations by manipulating strings of numbers in binary code. Each switch is known as a bit, and the more bits there are, the more powerful the computer is. Eight bits make a byte, and computer memory today is measured in terms of billions of bytes gigabytes, or Gb. Strictly speaking, since we are dealing in binary, a gigabyte is 230 bytes, but that is usually taken as read. Each switch in a quantum computer, however, is an entity that can be in a superposition of states. These are usually atoms, but you can think of them as being electrons that are either spin up or spin down. The difference is that in the superposition, they are both spin up and spin down at the same time 0 and 1. Each switch is called a qbit, pronounced cubit.

Using a rather subtle argument, Deutsch claims that an intelligent quantum computer would be able to remember the experience of temporarily existing in parallel realities.

Because of this quantum property, each qbit is equivalent to two bits. This doesnt look impressive at first sight, but it is. If you have three qbits, for example, they can be arranged in eight ways: 000, 001, 010, 011, 100, 101, 110, 111. The superposition embraces all these possibilities. So three qbits are not equivalent to six bits (2 x 3), but to eight bits (2 raised to the power of 3). The equivalent number of bits is always 2 raised to the power of the number of qbits. Just 10 qbits would be equivalent to 210 bits, actually 1,024, but usually referred to as a kilobit. Exponentials like this rapidly run away with themselves. A computer with just 300 qbits would be equivalent to a conventional computer with more bits than there are atoms in the observable Universe. How could such a computer carry out calculations? The question is more pressing since simple quantum computers, incorporating a few qbits, have already been constructed and shown to work as expected. They really are more powerful than conventional computers with the same number of bits.

Deutschs answer is that the calculation is carried out simultaneously on identical computers in each of the parallel universes corresponding to the superpositions. For a three-qbit computer, that means eight superpositions of computer scientists working on the same problem using identical computers to get an answer. It is no surprise that they should collaborate in this way, since the experimenters are identical, with identical reasons for tackling the same problem. That isnt too difficult to visualize. But when we build a 300-qbit machinewhich will surely happenwe will, if Deutsch is right, be involving a collaboration between more universes than there are atoms in our visible Universe. It is a matter of choice whether you think that is too great a load of metaphysical baggage. But if you do, you will need some other way to explain why quantum computers work.

Most quantum computer scientists prefer not to think about these implications. But there is one group of scientists who are used to thinking of even more than six impossible things before breakfast the cosmologists. Some of them have espoused the Many Worlds Interpretation as the best way to explain the existence of the Universe itself.

Their jumping-off point is the fact, noted by Schrdinger, that there is nothing in the equations referring to a collapse of the wave function. And they do mean the wave function; just one, which describes the entire world as a superposition of states a Multiverse made up of a superposition of universes.

Some cosmologists have espoused the Many Worlds Interpretation as the best way to explain the existence of the Universe itself.

The first version of Everetts PhD thesis (later modified and shortened on the advice of Wheeler) was actually titled The Theory of the Universal Wave Function. And by universal he meant literally that, saying:

Since the universal validity of the state function description is asserted, one can regard the state functions themselves as the fundamental entities, and one can even consider the state function of the whole universe. In this sense this theory can be called the theory of the universal wave function, since all of physics is presumed to follow from this function alone.

where for the present purpose state function is another name for wave function. All of physics means everything, including us the observers in physics jargon. Cosmologists are excited by this, not because they are included in the wave function, but because this idea of a single, uncollapsed wave function is the only way in which the entire Universe can be described in quantum mechanical terms while still being compatible with the general theory of relativity. In the short version of his thesis published in 1957, Everett concluded that his formulation of quantum mechanics may therefore prove a fruitful framework for the quantization of general relativity. Although that dream has not yet been fulfilled, it has encouraged a great deal of work by cosmologists since the mid-1980s, when they latched on to the idea. But it does bring with it a lot of baggage.

The universal wave function describes the position of every particle in the Universe at a particular moment in time. But it also describes every possible location of those particles at that instant. And it also describes every possible location of every particle at any other instant of time, although the number of possibilities is restricted by the quantum graininess of space and time. Out of this myriad of possible universes, there will be many versions in which stable stars and planets, and people to live on those planets, cannot exist. But there will be at least some universes resembling our own, more or less accurately, in the way often portrayed in science fiction stories. Or, indeed, in other fiction. Deutsch has pointed out that according to the MWI, any world described in a work of fiction, provided it obeys the laws of physics, really does exist somewhere in the Multiverse. There really is, for example, a Wuthering Heights world (but not a Harry Potter world).

That isnt the end of it. The single wave function describes all possible universes at all possible times. But it doesnt say anything about changing from one state to another. Time does not flow. Sticking close to home, Everetts parameter, called a state vector, includes a description of a world in which we exist, and all the records of that worlds history, from our memories, to fossils, to light reaching us from distant galaxies, exist. There will also be another universe exactly the same except that the time step has been advanced by, say, one second (or one hour, or one year). But there is no suggestion that any universe moves along from one time step to another. There will be a me in this second universe, described by the universal wave function, who has all the memories I have at the first instant, plus those corresponding to a further second (or hour, or year, or whatever). But it is impossible to say that these versions of me are the same person. Different time states can be ordered in terms of the events they describe, defining the difference between past and future, but they do not change from one state to another. All the states just exist. Time, in the way we are used to thinking of it, does not flow in Everetts MWI.

John Gribbin, described by the Spectator as one of the finest and most prolific writers of popular science around, is the author of, among other books, In Search of Schrdingers Cat, The Universe: A Biography, and Six Impossible Things, from which this article is excerpted. He is a Visiting Fellow in Astronomy at the University of Sussex, UK.

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The Many-Worlds Theory, Explained | The MIT Press Reader

1. What quantum physics tells us about reality  Financial Times
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3. Does God play dice? A Note on the 2022 Nobel Prize in Physics  The Week
4. Nobel Prize in Physics Boosts Quantum Encryption  Security Boulevard
5. Physics Nobel Prize Awarded to Three Pioneers of Quantum Mechanics The European Conservative  The European Conservative
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What quantum physics tells us about reality - Financial Times

Physicist Carlo Rovelli explains the strange principles of relational quantum mechanics - which says objects don't exist in their own right - and how it could unlock major progress in fundamental physics

By Michael Brooks

Carlo Rovelli at the Cornelia Parker exhibition, Tate Britain

David Stock

Carlo Rovelli stands in front of an exploding shed. Fragments of its walls and shattered contents parts of a childs tricycle, a record player, a shredded Wellington boot hang in mid-air behind him. I have come to meet the physicist and bestselling author at an exhibition at the Tate Britain art gallery in London. The scattered objects are the work of Cornelia Parker, one of the UKs most acclaimed contemporary artists, known for her large-scale installations that reconfigure everyday objects.

For Rovelli, based at Aix-Marseille University in France, Parkers work is meaningful because it mirrors his take on the nature of reality. I connect with the process: of her coming up with the idea, producing the idea, telling us about the idea and of us reacting to it, he tells me. We dont understand Cornelia Parkers work just by looking at it, and we dont understand reality just by looking at objects.

Rovelli is an advocate of an idea known as relational quantum mechanics, the upshot of which is that objects dont exist independently of each other. It is a concept that defies easy understanding, so Parkers reality-challenging exhibition seemed like it might be a helpful setting for a conversation about it and about what else Rovelli is up to. It is a happy coincidence that Parkers shed is called Cold Dark Matter, a reference to the unidentified stuff that is thought to make up most of the universe. Because Rovelli now thinks he knows how we might finally pin

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Carlo Rovelli on the bizarre world of relational quantum mechanics - New Scientist

Have you ever wondered whether theres more to reality than what we can see, perceive, detect, or otherwise observe? One of the most intriguing but speculative ideas of 20th and 21st century physics is the notion that our Universe, which seems to consist of three spatial and one temporal dimension, might possess additional, extra dimensions beyond the ones we can see. Originally thought up independently by Theodr Kaluza and Oskar Klein in an attempt to unify Einsteins General Relativity with Maxwells electromagnetism, the idea lives on in the modern context of quantum field theory and a specific extension of its ideas: string theory.

But for all of its mathematical beauty and elegance, does it have anything to do with our physical Universe? Thats what our Patreon supporter Benhead, who was thinking about this recent New York Times piece, wrote to inquire about:

Ive never really bought into the holographic thing as a physical concept. Im not even sure how well it works as a mathematical abstraction in the analogy I thought we were the image but what was real was the film.

The idea that the Universe is a hologram also known as the holographic principle or the holographic Universe is more than 20 years old now, but remains both as curious and as problematic as ever. Heres an overview of the concept.

This hologram of a DNA molecules double helix structure is projected with the use of mirrors, displaying a true three-dimensional appearance from any angle. This is because its possible, through the use of coherent light, to create a map of the light field of an object and encode it onto a flat surface.

If youve ever seen a hologram before, youve truly beheld a wondrous application of the optical behavior of light. Printed onto a two-dimensional surface, a hologram when it catches the light just right shows you not a standard two-dimensional image like youd typically see, but a fully three-dimensional image. Not only can the third dimension, depth, be readily perceived by your eyes, but as you change your viewing angle with respect to the hologram, the relative distance from your eye to various parts of the encoded, holographic image appears to change correspondingly as well.

It appears as though, behind the surface of the hologram, a fully three-dimensional world exists, and you can see its details just as surely as you could see the three-dimensional world reflected in a mirror.

This is because a hologram isnt simply a static image, but rather a light map of the three dimensional object/setting that went into creating the hologram itself. Creating a hologram is itself an instructive look at how light, optics, and physics come together to encode a higher-dimensional set of information onto a lower-dimensional surface.

Although a photograph encodes an image of the three-dimensional world onto a two-dimensional surface, the three-dimensional information about depth is flattened and lost. The difference between a photograph and a hologram is all about having not just a light image, but a light field encoded and mapped onto the lower-dimensional surface.

The way a photograph works, by contrast to a hologram, is very simple. Take light thats emitted or reflected from an object, focus it through a lens, and record it onto a flat surface. Thats not only how photography works, but also how you physically see objects biologically, as the lens in your eyeball focuses the light onto your retina, where the rods and cones on the back of your eye record it, send it to your brain, and there it gets processed into an image.

But by using coherent light, such as that from a laser, and a special emulsion on the recording surface, youre no longer limited to recording a light image, but rather you can record and create a map of the entire light field. Part of the information encoded in a light field is the three-dimensional position of every object within the image, including features such as:

All of these properties are encoded in the light field, and are faithfully recorded onto the two-dimensional hologram surface. When that surface is then properly illuminated, it will display to any observer the full suite of recorded three-dimensional information, and will do so from every possible perspective that its viewable from. By printing this two-dimensional light field/map onto a metallic film, you can create a conventional hologram.

This photograph of a hologram at the MIT museum looks like a three-dimensional object, but is only a two-dimensional light field encoded onto the surface of a hologram. When properly illuminated, the three-dimensional properties can be clearly seen.

The big idea behind a hologram is actually ubiquitous in physics: the notion that you can examine a lower-dimensional surface and obtain not only substantial information about the higher-dimensional reality that is encoded on it, but complete information that reveals to you the full set of physical properties concerning that higher-dimensional reality. The key is to have the lower-dimensional surface serve as the boundary of your higher-dimensional space; if you can both:

you can then draw conclusions about the precise physical state that occurs inside that region, fully.

You can accomplish this in electromagnetism, for example, by measuring any of three properties on the surface enclosing the region: with Dirichlet, Neumann, or Robin boundary conditions. You can do something analogous in General Relativity, with the caveat that if youre not dealing with a closed spacetime manifold, you must add an additional boundary term. In many areas of physics, if you know the laws that govern the boundary and the region of space that it encloses, simply measuring enough of the properties encoded on the boundary enables you to determine the full set of physical properties that describe the inside.

This set of radiofrequency cavities within a linear accelerator in Australia consist of a very intricate electromagnetic setup. If you were to draw an imaginary two-dimensional boundary around any region either inside or outside this cavity, the information encoded on the surface, if you measured enough of it, could tell you what was going on in the volume inside that boundary as well.

This type of analysis even has applications to black holes, although theyve only ever been tested in quantum analogue systems, as we have yet to actually measure a black hole precisely enough to test the idea. In theory, whenever individual quanta fall into a black hole and remember, black holes are fundamentally entities that exist in our Universe with three spatial dimensions they carry all the quantum information that they previously possess with them into the black hole.

But when black holes decay, which they do via the emission of Hawking radiation, the radiation that comes out should simply possess a blackbody spectrum, with no memory of things like the mass, charge, spin, polarization, or baryon/lepton number of the quanta that went into creating them. This non-conservative property is known as the black hole information paradox, with the only two realistic possibilities being that either information is not conserved, after all, or that the information must somehow escape the black holes clutches during the process of evaporation.

Its possible, even likely, that theres a two dimensional surface, either on or interior to the event horizon, where all of the information that went into and radiated away from the black hole is preserved. Its possible that the holographic principle, as applied to black holes, can actually solve the black hole information paradox, preserving unitarity (the idea that the sum of the probabilities of all possible outcomes must add up to 1) in the process.

Encoded on the surface of the black hole can be bits of information, proportional to the event horizons surface area. When the black hole decays, it decays to a state of thermal radiation. Whether that information survives and is encoded in the radiation or not, and if so, how, is not a question that our current theories can provide the answer to.

Now, here we are, in what appears to us to be a four-dimensional spacetime: with three spatial and one temporal dimension. But what if this isnt representative of the full picture of reality; what if there are:

Its a wild idea, but one that has its roots in a seemingly unrelated discipline: String Theory.

String Theory grew from a proposalthe string modelto explain the strong interactions, as the insides of protons, neutrons and other baryons (and mesons) were known to have a composite structure. It gave a whole bunch of nonsensical predictions, though, that didnt correspond to experiments, including the existence of a spin-2 particle. But people recognized if you took that energy scale way up, toward the Planck scale, the string framework could unify the known fundamental forces with gravity, and thus String Theory was born.

The idea that the forces, particles, and interactions that we see today are all manifestations of a single, overarching theory is an attractive one, requiring extra dimensions and lots of new particles and interactions. The lack of a single verified prediction of String Theory thats distinct from what the Standard Model predicts, plus internal inconsistencies with the Universe as we understand it, both stand as enormous strikes against it.

A feature (or flaw, depending on how you look at it) of this attempt at a holy grail of physics is that it absolutely requires a large number of extra dimensions. So a big question then becomes how do we get our Universe, which has justthreespatial dimensions, out of a theory that gives us many others? And which string theory, since there are many possible realizations of string theory, is the right one?

Perhaps, the realization goes, the many different string theory models and scenarios that are out there are actually all different aspects of the same fundamental theory, seen from a different point of view. In mathematics, two systems that are equivalent to one another are known as dual, and one surprising discovery thats related to a hologram is that sometimes two systems that are dual to one another have different numbers of dimensions.

The reason physicists get very excited about this is that in 1997, physicist Juan Maldacena proposedthe AdS/CFT correspondence, which claimed that our three dimensional (plus time) Universe, with its quantum field theories describing elementary particles and their interactions, was dual to a higher-dimensional spacetime (anti-de Sitter space) that plays a role in quantum theories of gravity.

The idea that a higher-dimensional space, often called the bulk, is mathematically equivalent to a lower-dimensional space that defined the boundary of the bulk, known as the brane, is the core idea at the root of the AdS/CFT correspondence. This lower-dimensional analogue of the 5-to-4 dimensional relation derived by Juan Maldacena in 1997 is shown here.

For the past 25 years, physicists and mathematicians have explored this correspondence to the best of our abilities, and it turns out that it has been usefully applied to a number of condensed matter and solid state physical systems. As far as applications to our entire Universe, however, and specifically to a framework where we have to have at least 10 dimensions total (as required by String Theory), we run into a significant set of problems that have not been so easy to solve.

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For one, were very certain we dont live in anti-de Sitter space, because weve measured the effects of dark energy, and those effects show us that the Universes expansion is accelerating in a fashion thats consistent with a positive cosmological constant. A spacetime with a positive cosmological constant looks like de Sitter space, and specifically not like anti-de Sitter space, which would have a negative cosmological constant. Mathematically, because of a series of problems (like the bubble nucleation/percolation problem) that arise in de Sitter space and not in anti-de Sitter space, we cannot build that same correspondence.

The string landscape might be a fascinating idea thats full of theoretical potential, but it cannot explain why the value of such a finely-tuned parameter like the cosmological constant, the initial expansion rate, or the total energy density have the values that they do. One of the more important deficiencies of the AdS/CFT correspondence is that AdS stands for anti-de Sitter space, which requires a negative cosmological constant. However, the observed Universe has a positive cosmological constant, implying de Sitter space; there is no equivalent dS/CFT correspondence.

For another, the only dualities weve ever discovered relate the properties of the higher-dimensional space to its lower-dimensional boundary: a reduction in dimension by one. Two-dimensional holograms can only encode three-dimensional information; the four-dimensional conformal field theories (CFTs) that are part of the AdS/CFT correspondence only apply to five-dimensional anti-de Sitter spaces. The question of compactification of how you get down to no more than five dimensions in the first place remains unaddressed.

However, theres another aspect of the AdS/CFT correspondence that many find compelling. Sure, those two problems are real: we have the wrong sign for the cosmological constant and the wrong number of dimensions. However, when two spaces of different dimensions are mathematically dual to one another, one can sometimes obtain more information about the higher-dimensional space than you might initially think. Sure, theres less information available on a lower-dimensional boundary of a surface than inside the volume of the full space enclosed by the surface. That implies that when you measure one thing thats happening on the boundarys surface, you might wind up learning multiple things that are occurring inside of the larger, higher-dimensional volume.

The idea that two quanta could be instantaneously entangled with one another, even across large distances, is often talked about as the spookiest part of quantum physics. If reality were fundamentally deterministic and were governed by hidden variables, this spookiness could be removed. Unfortunately, attempts to do away with this type of quantum weirdness have all failed, but the AdS/CFT correspondence has led some to remain hopeful this could be possible by invoking extra dimensions.

One wild possibility potentially related to 2022s Nobel Prize in physics on quantum entanglement is that something occurring in the larger-dimensional space may wind up relating two disparate, seemingly disconnected regions along the lower-dimensional boundary. If youre bothered by the notion that measuring one entangled particle appears to give you information about the other entangled pair instantaneously, appearing as though communication is occurring faster-than-light, the holographic principle might be your best hope for a physically-rooted savior.

Nevertheless, the past 25 years have arguably brought us no closer to finding extra dimensions, understanding whether or not theyre relevant for our reality, or delivering any important theoretical insights that help us better comprehend our own Universe. Duality, however, cannot be denied: it is a mathematical fact. The AdS/CFT correspondence will continue to be mathematically interesting, but the two major problems with it:

loom large and remain unaddressed. The idea that the Universe is a hologram, known as the holographic Universe, may indeed someday lead us to quantum gravity. Until these puzzles are solved, however, its impossible to foresee how well get there.

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Research Fellow positions are open in the research group of Dr. Gong Xiao, at the Department of Electrical and Computer Engineering, National University of Singapore (NUS). The Research Fellows will work closely with the Principal Investigator (PI) on one or more research projects. The project aims to explore advanced photonics and electronic devices for future advanced integrated circuits and quantum technology.

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There are certain properties about the Universe that for better or worse we take for granted. The laws of physics, we presume, are the same at other locations in space and other moments in time as they are in the here-and-now. The fundamental constants that relate various physical properties of our Universe are assumed to truly possess the same, constant value at every time and place. The fact that the Universe appears to be consistent with these presumptions at least, to the limits of our observations seems to support this view, placing great constraints on how much its possible these various aspects of reality have evolved.

Wherever and whenever we can measure or infer the fundamental physical properties of the Universe, it appears that they do not change over time or space: they are the same for everybody. But earlier on, the Universe underwent transitions: from higher-energy states to lower-energy ones. Some of the conditions that arose spontaneously under those high-energy conditions could no longer persist at lower energies, rendering them unstable. Unstable states all have one thing in common: they decay. And in one of the most terrifying realizations of all, weve learned that the fabric of our Universe itself may inherently be one of those unstable things as well. Heres what we know, today, about how precarious our continued existence is.

Every planet orbiting a star has five location around it, Lagrange points, that co-orbit. An object precisely located at L1, L2, L3, L4, or L5 will continue to orbit the Sun with precisely the same period as Earth does, meaning that the Earth-spacecraft distance will be constant. L1, L2, and L3 are unstable points of equilibrium, requiring periodic course corrections to maintain a spacecrafts position there, while L4 and L5 are stable. The JWST, for example, successfully inserted itself in orbit around L2, and must always face away from the Sun for cooling purposes.

In any physical system that is, a system made up of particles that interact via one or more forces theres at least one way to configure them that is more stable than any other way to do it. This is what we call the lowest-energy state, or the ground-state, of a system.

When we see something like a ball balanced precariously atop a hill, this appears to be what we call a finely-tuned state, or a state of unstable equilibrium. A much more stable position is for the ball to be down somewhere at the bottom of the valley. Whenever we encounter a finely-tuned physical situation, there are good reasons to seek a physically-motivated explanation for it; when we have hills with false minima on them, its possible to get caught up in one and not arrive at the true minimum.

Only, that last example has a catch to it: sometimes, if your conditions arent precisely right, your ball wont end up in the lowest-energy state possible. Rather, it can roll into a valley thats still lower than where it started, but that doesnt represent the true ground state of the system. This state can happen naturally for a great variety of physical systems, and we generally think about it as though the system is hung up in some sort of false minimum. Even though it would be more energetically stable in the ground state, or in its true minimum, it cant necessarily get there on its own.

What can you do when youre stuck in a false minimum?

If youre a classical system, the only solution is Sisyphean: you have to input enough energy into your system irrespective of whether thats kinetic energy, chemical energy, electrical energy, etc. to kick that system out of the false minimum. If you can overcome the next energy barrier, you have the opportunity to wind up in an even more stable state: a state that takes you down closer to, and possible even all the way to, the ground state. Only in the true ground state is it impossible to transition down to an even lower-energy state.

If you draw out any potential, it will have a profile where at least one point corresponds to the lowest-energy, or true vacuum, state. If there is a false minimum at any point, that can be considered a false vacuum. In the classical world, you must overcome the hill or barrier confining you to the false minimum to arrive elsewhere. But, assuming this is a quantum field, its possible to quantum tunnel directly from the false vacuum to the true vacuum state.

Thats whats true for a classical system. But the Universe isnt purely classical in nature; rather, we live in a quantum Universe. Inherently quantum systems not only undergo these same types of reorganizations as classical systems where inputting energy can kick them out of unstable equilibrium states but they have another effect that theyre subject to: quantum tunneling.

Quantum tunneling is a probabilistic venture, but one that doesnt require what you might think of as activation energy to get over that hump keeping you in that unstable equilibrium state. Instead, dependent on specifics like how far your field is from the true equilibrium state and how high the barrier is preventing you from leaving the false minimum that youre stuck in, theres a certain probability that you can spontaneously leave your unstable equilibrium state and find yourself, all of a sudden, in a more stable (or even the true) minimum of your quantum system.

Unlike in the purely classical case, this can happen spontaneously, with no outside, energetic influence or impetus required.

This generic illustration of quantum tunneling assumes there is a high, thin, but finite barrier separating a quantum wavefunction on one side of the x-axis from the other. While most of the wavefunction, and hence the probability of the field/particle that its a proxy for, reflects and remains on the original side, there is a finite, non-zero probability of tunneling through to the other side of the barrier.

Some common examples of quantum systems that exhibit tunneling involve atoms and their constituent particles.

Heavy, unstable elements will radioactively decay, typically by emitting either an alpha particle (a helium nucleus) or by undergoing beta decay, as shown here, where a neutron converts into a proton, electron, and anti-electron neutrino. Both of these types of decays change the elements atomic number, yielding a new element different from the original, and result in a lower mass for the products than for the reactants. These quantum transitions are spontaneous but probabilistic and unpredictable in nature, but always take the overall system into a more stable, lower-energy state overall.

Well, you know what the ultimate quantum system is?

Empty space itself. Empty space even without any particles, quanta, or external fields present still appears to have a non-zero amount of energy inherent to it. This evidences itself through the observed effects of dark energy, and even though it corresponds to a very small energy density of barely more than a protons worth of energy per cubic meter of space, thats still a positive, finite, non-zero value.

We also know that regardless of how much you remove from any particular region of space, you cannot get rid of the fundamental quantum fields that describe the interactions and forces inherent to the Universe. Just as you cannot have space without the laws of physics, you cannot have a region without the presence of quantum fields owing to (at least) the forces of the Standard Model.

It had long been assumed, although it was untested, that because we do not know how to calculate the energy inherent to empty space what quantum field theorists call the vacuum expectation value in any way that doesnt yield complete nonsense, it probably all just cancels out. But the measurement of dark energy, and that it affects the expansion of the Universe and must have a positive, non-zero value, tells us that it cannot all cancel out. The quantum fields permeating all of space give a positive, non-zero value to the quantum vacuum.

Even in the vacuum of empty space, devoid of masses, charges, curved space, and any external fields, the laws of nature and the quantum fields underlying them still exist. If you calculate the lowest-energy state, you may find that it is not exactly zero; the zero-point (or vacuum) energy of the Universe appears to be positive and finite, although small. We do not know whether this is a true vacuum state or not.

Now, heres the big question: is the value that were measuring for dark energy, today, the same value that the Universe recognizes as its true minimum for the contributions of the quantum vacuum to the energy density of space?

If it is, then great: the Universe will be stable forever and ever, as theres no lower-energy state for it to ever quantum tunnel into.

But if were not in a true minimum, and there is a true minimum out there that actually represents a more stable, lower-energy configuration than the one we currently find ourselves (and the entire Universe) in, then theres always a probability that well eventually quantum tunnel into that true vacuum state.

This latter option, unfortunately, is not so great. The vacuum state of the Universe, remember, depends on the fundamental laws, quanta, and constants that underlie our Universe. If we spontaneously transitioned from our current vacuum state to a different, lower-energy one, it isnt just that space would now take on a different configuration. In fact, by necessity, wed have at least one of:

If this change were to spontaneously occur, what happened next would be a Universe-ending catastrophe.

In the far future, its conceivable that the quantum vacuum will decay from its current state to a lower-energy, still more stable state. If such an event were to occur, every proton, neutron, atom, and other composite structure in the Universe would spontaneously destroy itself in a remarkably destructive event, whose effects would propagate and ripple outward in a sphere at the speed of light. This bubble of destruction would be unnoticeable until it arrived.

Wherever the quantum vacuum transitioned from this false vacuum state into the true vacuum state, everything that we recognize as a bound state of quanta things like protons-and-neutrons, atomic nuclei, atoms, and everything that they make up, for example would immediately be destroyed. As the fundamental particles that compose reality rearrange themselves according to these new rules, everything from molecules to planets to stars to galaxies would come undone, including human beings and any living organisms.

Without knowing what the true vacuum state is and what these new sets of laws, interactions, and constants our current ones would be replaced with, we have no way of predicting what sorts of new structures would emerge. But we can know that not only would the ones we see today cease to exist, but that wherever this transition occurred, it would propagate outward at the speed of light, infecting space as it expanded with a great bubble of destruction. Even with the Universe expanding, and even with that expansion accelerating due to dark energy, if a vacuum decay event such as the one envisioned here occurred anywhere within 18 billion light-years of us, at present, it would eventually reach us, destroying every atom at the speed of light in a Ghostbusters-level event when it did.

The size of our visible Universe (yellow), along with the amount we can reach (magenta) if we left, today, on a journey at the speed of light. The limit of the visible Universe is 46.1 billion light-years, as thats the limit of how far away an object that emitted light that would just be reaching us today would be after expanding away from us for 13.8 billion years. Anything that occurs, right now, within a radius of 18 billion light-years of us will eventually reach and affect us; anything beyond that point will not.

Is this something we actually have to worry about?

Maybe. There are consistency conditions that must be obeyed by the laws of physics, and there are parameters that we need to measure in order to find out whether we live in a:

In the context of quantum field theory, this means that if we take the properties of the Standard Model, including the particle content of the Universe, the interactions that exist between particles, and the relationships that govern the overarching rules, then we can measure the parameters of the particles within it (such as the rest masses of the particles), and determine what type of Universe we live in.

Right now, the two most important parameters in performing such a calculation are the mass of the top quark and the Higgs boson. The best value we have for the top mass is 171.770.38 GeV, and the best value we have for the Higgs mass is 125.380.14 GeV. This appears extremely close to the metastable/stable border, where the blue dot and the three blue circles below represent 1-sigma, 2-sigma, and 3-sigma departures from the mean value.

Based on the masses of the top quark and the Higgs boson, we could either live in a region where the quantum vacuum is stable (true vacuum), metastable (false vacuum), or unstable (where it cannot stably remain). The evidence suggested, but did not prove, that we occupy a false vacuum at the time this figure was published: in 2018. Since then, as of 2022, the values of the top mass and the Higgs mass have shifted the best-fit contours closer to the region of stability.

Does this mean the Universe is really in a metastable state, and the quantum vacuum may actually someday decay where we are, ending the Universe in a catastrophic fashion thats very different from the slow, gradual heat death wed otherwise expect?

Travel the Universe with astrophysicist Ethan Siegel. Subscribers will get the newsletter every Saturday. All aboard!

That depends. It depends on which side of that curve were on, and that depends on whether weve correctly identified all of the underlying laws of physics and the contributors to the quantum vacuum, whether weve done our calculations correctly assuming weve written down the underlying equations properly, and whether our measurements for the masses of the constituent particles of the Universe are accurate and precise. If we want to know for certain, we know at least this much: we need a better determination of these measurable parameters, and that means creating more top quarks and Higgs bosons, measured to at least the best precision we can currently muster.

The Universe may fundamentally be unstable, but if it is, well never see this bubble of destruction caused by vacuum decay coming our way. No information-carrying signal can travel faster-than-light, and that means that if the vacuum does decay, our first warning of its arrival will coincide with our instantaneous demise. Nevertheless, if our Universe truly is fundamentally unstable, Id want to know. Would you?

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Is the Universe fundamentally unstable? - Big Think

This weeks Good News bulletin brings you everything you need to know about the people who won the Nobel Awards, the people who as well as contributing to the significant progress of humanity can also give us a lesson in humility and determination.

Good News is highlighting the Nobel prizes, though they dont represent one-off news events, because they reward the slow and broader developments that have reshaped the world we live in.

The 2022 Nobel Prize in Chemistry

The Royal Swedish Academy of Sciences awarded the 2022 Nobel Prize in Chemistry in equal shares to Carolyn Bertozzi, Stanford University, California, USA; Morton Meldal, University of Copenhagen, Denmark; and Barry Sharpless, Scripps Research, La Jolla, California, USA.

They received the prize for the development of click chemistry and bioorthogonal chemistry.

Click chemistry, coined in 2000, is partly explained by its name. Its basically snapping molecules together.

They say: imagine if you could attach small chemical buckles to different types of building blocks. Then imagine you could link these buckles together and produce molecules of greater complexity and variation. Thats clicking chemistry.

The other part of the chemistry prize, for the concept of bioorthogonal chemistry, is still in its early phases.

I think there are probably many new reactions to be discovered and invented, said Carolyn Bertozzi in a statement.

The biotech industry, the pharmaceutical industry and the medical industry with new approaches to treating and diagnosing diseases will be strongly impacted by click chemistry, says Bertozzi.

Its basically a superpower that opens the door to all kinds of interesting applications.

Bertozzi says that before the advent of bioorthogonal chemistry and then the related click chemistry developed by professors Sharpless and Meldal, there was really no way to study certain biological processes. They were just invisible to the scientists. But these chemistries make those processes visible.

Because the Nobel Academy is in northern Europe, and the winners are announced in the morning, laureates in the Americas are usually woken up to the incredible news.

Watch the video above to see the laureates reactions after being told in the early hours of the morning they had won a Nobel Prize.

Immediately I thought, maybe, maybe it's not real. Maybe it's something, you know. But it was real, said Morten Meldal, who won the award jointly with Carolyn Bertozzi and Barry Sharpless.

Meldal says his hope is that the award will help persuade young people to take chemistry as a discipline, which is a little bit difficult at the moment. He thinks chemistry is the solution to many of our challenges.

Barry Sharpless, the third recipient of the Nobel Prize in Chemistry, said he just wanted to create a chemistry that worked "in hours instead of days."

"I guess I've always been impatient. I like to go in the lab, mix up some things that work, and I go on from there. If I have to wait a day or two, I just can't. That's not good. So I'm trying to create a chemistry that moves in hours instead of days," he said.

The 2022 Nobel Prize in Medicine

The Royal Swedish Academy of Sciences awarded the 2022 Nobel Prize in Medicine to Svante Pbo, a Swedish scientist, for his discoveries in human evolution.

Pbos sequencing of the DNA of Neanderthals proved that our ancestors had sex and children with them.

"What we do is to look for the genetic material, for DNA from people who have lived here long before us and try to see how they are related to us, and how they are related to other forms of humans that were also here, such as Neanderthals, he said.

He retrieved genetic material from 40,000-year-old bones, producing a complete Neanderthal genome and opening up the study of ancient DNA as a field.

The scientist, like many of the other laureates, said that what drives his work is mere curiosity. It is as if you do an archaeological excavation to find out about the past. We make excavations in the human genome.

But his curiosity had a deep impact; his research has provided key insights into our immune system and what makes us unique compared to our extinct cousins.

We have discovered, for example, that in the COVID pandemic the greatest risk factor to becoming severely ill and even dying when you're infected with the virus has come over to modern people from Neanderthals, says Pbo.

Nils-Gran Larsson, a Nobel Assembly member, has called it "a basic scientific discovery.

We already know that it affects our defence against different types of infections for instance, or how we can cope with high altitudes, but like all great discoveries in basic science, more and more insights will come over the next decades."

The 2022 Nobel Prize in Physics

The joint winners of the 2022 Nobel Prize in Physics were Alain Aspect, from the Universite Paris-Saclay and cole Polytechnique Palaiseau, France; John F Clauser, J.F. Clauser and Associates, Walnut Creek, California, USA; and to Anton Zeilinger, from University of Vienna, Austria.

The award celebrates their work in quantum information science and their discoveries on how unseen particles, such as tiny bits of matter, can be linked, or "entangled", with each other, even when they are separated by large distances.

Clauser developed quantum theories first put forward in the 1960s into a practical experiment. Aspect closed a loophole in those theories, and Zeilinger demonstrated a phenomenon called quantum teleportation that effectively allows information to be transmitted over distances.

Their research has provided the foundations for many practical applications of quantum science, particularly encryption.

Clauser said the Nobel had been awarded for work he did more than 50 years ago when he was just a graduate student.

I wrote a paper in 1969 proposing to do an original experiment testing the foundations of quantum mechanics everybody told me I was nuts, that I would ruin my career.

Zeilinger also made reference to the way his work had been dismissed in the past.

During the first experiments I was sometimes asked by the press, 'What is all of this supposed to be good for?' And I told them: 'I can tell you with pride this is good for nothing. I am only doing this out of curiosity because I have been excited by quantum physics from the very moment I first heard about it. Because of the mathematical beauty of this description.

Zeilinger, who is based at the University of Vienna, said he was grateful to Austrian and European taxpayers, as they have enabled him to pursue his work regardless of the possible benefits it might have.

Alain Aspect, the third winner of the Nobel Prize in Physics, thinks quantum is fantastic.

[Quantum] has been on the agenda for more than one century and there are still a lot of mysteries, of stranger things to discover in the quantum. It shows that the quantum is still alive. Because of course this prize today, in my opinion, is anticipating, one that will one day be on quantum technologies."

The 2022 Nobel Prize in Literature

The highest literary prize went to French author Annie Ernaux. She is the first female French Nobel literature winner and just the 17th woman among the 119 Nobel literature laureates.

Anders Olsson, chairman of the Nobel Committee for literature, said Ernaux's writing is subordinated throughout the process of time, adding that Nowhere else does the power of social conventions over our lives play such an important role as in Les Annes.

Published in English in 2008, The Years has been called the first collective autobiography.

Ernaux gave a moving speech at the Nobel academy: It is enormous luck that I was able to accomplish this. The Nobel Prize does not seem part of reality for me just yet, but it is true that I feel it brings a new responsibility," she said.

"I will fight until my last breath so that women can choose to be mothers or not to be mothers. It is a fundamental right.

The 2022 Nobel Peace Prize

The Peace Prize, considered the most significant of them all, and which is awarded to those who have conferred the greatest benefit to humankind, was given to Ales Bialiatski, a Belarusian human rights defender; the Russian human rights organisation Memorial, and the Ukrainian human rights organisation Center for Civil Liberties, which has worked to document Russian war crimes against Ukrainian civilians.

Oleksandra Romantsova, executive director of the Center for Civil Liberties, took to the stage to make a powerful condemnation of the war in Ukraine and the oppressive Belarusian government:

"The absence of respect towards human rights sooner or later led to the war. Lukashenko and Putin, the whole regime, and all people who commit war crimes with their own hands against humanity must be punished," she said.

Ales Bialiatski is currently in prison, but his recognition was nonetheless applauded.

I am really honoured and delighted this award was given to Ales Bialiatski He is a wonderful person, and in 1995 he established the Human Rights Center Viasna in Belarus. He, many times, was in prison for his views, for his intention to protect people and human rights in our country. And, of course, he deserves to be the winner of the Peace Prize," said Sviatlana Tsikhanouskaya, a Belarusian opposition leader.

Tsikhanouskaya said the award to Ales Bialiatski would help to bring more attention to the humanitarian situation in Belarus.

Ales Bialiatski has now been in prison for more than one year, and he is suffering a lot in punishment cells in prison. But there are thousands of other people who are detained because of their political views.

Tatyana Glushkova, board member of the Russian Memorial human rights centre, the third laureate of the award, said that after everything that happened in the past several months, the award was a sign that their work, whether it is recognised by Russian authorities or not, it is important, It is important for the world. It is important for people in Russia."

And thats all from this special edition of the Good News round-up. If you felt inspired by these extraordinary and passionate people, share this episode with your friends.

See you next time, and remember, some news can be good news.

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Whoever said, You cant get something from nothing must never have learned quantum physics. As long as you have empty space the ultimate in physical nothingness simply manipulating it in the right way will inevitably cause something to emerge. Collide two particles in the abyss of empty space, and sometimes additional particle-antiparticle pairs emerge. Take a meson and try to rip the quark away from the antiquark, and a new set of particle-antiparticle pairs will get pulled out of the empty space between them. And in theory, a strong enough electromagnetic field can rip particles and antiparticles out of the vacuum itself, even without any initial particles or antiparticles at all.

Previously, it was thought that the highest particle energies of all would be needed to produce these effects: the kind only obtainable at high-energy particle physics experiments or in extreme astrophysical environments. But in early 2022, strong enough electric fields were created in a simple laboratory setup leveraging the unique properties of graphene, enabling the spontaneous creation of particle-antiparticle pairs from nothing at all. The prediction that this should be possible is 70 years old: dating back to one of the founders of quantum field theory, Julian Schwinger. The Schwinger effect is now verified, and teaches us how the Universe truly makes something from nothing.

This chart of the particles and interactions details how the particles of the Standard Model interact according to the three fundamental forces that Quantum Field Theory describes. When gravity is added into the mix, we obtain the observable Universe that we see, with the laws, parameters, and constants that we know of governing it. Mysteries, such as dark matter and dark energy, still remain.

In the Universe we inhabit, its truly impossible to create nothing in any sort of satisfactory way. Everything that exists, down at a fundamental level, can be decomposed into individual entities quanta that cannot be broken down further. These elementary particles include quarks, electrons, the electrons heavier cousins (muons and taus), neutrinos, as well as all of their antimatter counterparts, plus photons, gluons, and the heavy bosons: the W+, W-, Z0, and the Higgs. If you take all of them away, however, the empty space that remains isnt quite empty in many physical senses.

For one, even in the absence of particles, quantum fields remain. Just as we cannot take the laws of physics away from the Universe, we cannot take the quantum fields that permeate the Universe away from it.

For another, no matter how far away we move any sources of matter, there are two long-range forces whose effects will still remain: electromagnetism and gravitation. While we can make clever setups that ensure that the electromagnetic field strength in a region is zero, we cannot do that for gravitation; space cannot be entirely emptied in any real sense in this regard.

Instead of an empty, blank, three-dimensional grid, putting a mass down causes what would have been straight lines to instead become curved by a specific amount. No matter how far away you get from a point mass, the curvature of space never reaches zero, but always remains, even at infinite range.

But even for the electromagnetic force even if you completely zero out the electric and magnetic fields within a region of space theres an experiment you can perform to demonstrate that empty space isnt truly empty. Even if you create a perfect vacuum, devoid of all particles and antiparticles of all types, where the electric and magnetic fields are zero, theres clearly something thats present in this region of what a physicist might call, from a physical perspective, maximum nothingness.

Travel the Universe with astrophysicist Ethan Siegel. Subscribers will get the newsletter every Saturday. All aboard!

All you need to do is place a set of parallel conducting plates in this region of space. Whereas you might expect that the only force theyd experience between them would be gravity, set by their mutual gravitational attraction, what actually winds up happening is that the plates attract by a much greater amount than gravity predicts.

This physical phenomenon is known as the Casimir effect, and was demonstrated to be true by Steve Lamoreaux in 1996: 48 years after it was calculated and proposed by Hendrik Casimir.

The Casimir effect, illustrated here for two parallel conducting plates, excludes certain electromagnetic modes from the interior of the conducting plates while permitting them outside of the plates. As a result, the plates attract, as predicted by Casimir in the 1940s and verified experimentally by Lamoreaux in the 1990s.

Similarly, in 1951, Julian Schwinger, already a co-founder of the quantum field theory that describes electrons and the electromagnetic force, gave a complete theoretical description of how matter could be created from nothing: simply by applying a strong electric field. Although others had proposed the idea back in the 1930s, including Fritz Sauter, Werner Heisenberg, and Hans Euler, Schwinger himself did the heavy lifting to quantify precisely under what conditions this effect should emerge, and henceforth its been primarily known as the Schwinger effect.

Normally, we expect there to be quantum fluctuations in empty space: excitations of any and all quantum fields that may be present. The Heisenberg uncertainty principle dictates that certain quantities cannot be known in tandem to arbitrary precision, and that includes things like:

While we normally express the uncertainty principle in terms of the first two entities, alone, the other applications can have consequences that are equally profound.

This diagram illustrates the inherent uncertainty relation between position and momentum. When one is known more accurately, the other is inherently less able to be known accurately. Every time you accurately measure one, you ensure a greater uncertainty in the corresponding complementary quantity.

Recall that, for any force that exists, we can describe that force in terms of a field: where the force experienced by a particle is its charge multiplied by some property of the field. If a particle passes through a region of space where the field is non-zero, it can experience a force, depending on its charge and (sometimes) its motion. The stronger the field, the greater the force, and the stronger the field, the greater the amount of field energy exists in that particular region of space.

Even in purely empty space, and even in the absence of external fields, there will still be some non-zero amount of field energy that exists in any such region of space. If there are quantum fields everywhere, then simply by Heisenbergs uncertainty principle, for any duration of time that we choose to measure this region over, there will be an inherently uncertain amount of energy present within that region during that time period.

The shorter the time period were looking at, the greater the uncertainty in the amount of energy in that region. Applying this to all allowable quantum states, we can begin to visualize the fluctuating fields, as well as fluctuating particle-antiparticle pairs, that pop in-and-out of existence due to all of the Universes quantum forces.

Even in the vacuum of empty space, devoid of masses, charges, curved space, and any external fields, the laws of nature and the quantum fields underlying them still exist. If you calculate the lowest-energy state, you may find that it is not exactly zero; the zero-point (or vacuum) energy of the Universe appears to be positive and finite, although small.

Now, lets imagine turning up the electric field. Turn it up, higher and higher, and what will happen?

Lets take an easier case first, and imagine theres a specific type of particle already present: a meson. A meson is made of one quark and one antiquark, connected to one another through the strong force and the exchange of gluons. Quarks come in six different flavors: up, down, strange, charm, bottom, and top, while the anti-quarks are simply anti-versions of each of them, with opposite electric charges.

The quark-antiquark pairs within a meson sometimes have opposite charges to one another: either + and - (for up, charm, and top) or + and - (for down, strange, and bottom). If you apply an electric field to such a meson, the positively charged end and the negatively charged end will be pulled in opposite directions. If the field strength is great enough, its possible to pull the quark and antiquark away from one another sufficiently so that new particle-antiparticle pairs are ripped out of the empty space between them. When this occurs, we wind up with two mesons instead of one, with the energy required to create the extra mass (via E = mc) coming from the electric field energy that ripped the meson apart in the first place.

When a meson, such as a charm-anticharm particle shown here, has its two constituent particles pulled apart by too great an amount, it becomes energetically favorable to rip a new (light) quark/antiquark pair out of the vacuum and create two mesons where there was one before. A strong enough electric field, for long-enough lived mesons, can cause this to occur, with the needed energy for creating more massive particles coming from the underlying electric field.

Now, with all of that as background in our minds, lets imagine weve got a very, very strong electric field: stronger than anything we could ever hope to make on Earth. Something so strong that it would be like taking a full Coulomb of charge around ~1019 electrons and protons and condensing each of them into a tiny ball, one purely of positive charge and one purely of negative charge, and separating them by only a meter. The quantum vacuum, in this region of space, is going to be extremely strongly polarized.

Strong polarization means a strong separation between positive and negative charges. If your electric field in a region of space is strong enough, then when you create a virtual particle-antiparticle pair of the lightest charged particle of all (electrons and positrons), you have a finite probability of those pairs being separated by large enough amounts due to the force from the field that they can no longer reannihilate one another. Instead, they become real particles, stealing energy from the underlying electric field in order to keep energy conserved.

As a result, new particle-antiparticle pairs come to exist, and the energy required to make them, from E = mc, reduces the exterior electric field strength by the appropriate amount.

As illustrated here, particle-antiparticle pairs normally pop out of the quantum vacuum as a consequences of Heisenberg uncertainty. In the presence of a strong enough electric field, however, these pairs can be ripped apart in opposite directions, causing them to be unable to reannihilate and forcing them to become real: at the expense of energy from the underlying electric field.

Thats what the Schwinger effect is, and unsurprisingly, its never been observed in a laboratory setting. In fact, the only places where it was theorized to occur was in the highest-energy astrophysical regions to exist in the Universe: in the environments surrounding (or even interior to) black holes and neutron stars. But at the great cosmic distances separating us from even the nearest black holes and neutron stars, even this remains conjecture. The strongest electric fields weve created on Earth are at laser facilities, and even with the strongest, most intense lasers at the shortest pulse times, we still arent even close.

Normally, whenever you have a conducting material, its only the valence electrons that are free to move, contributing to conduction. If you could achieve large enough electric fields, however, you could get all of the electrons to join the flow. In January of 2022, researchers at the University of Manchester were able to leverage an intricate and clever setup involving graphene an incredibly strong material that consists of carbon atoms bound together in geometrically optimal states to achieve this property with relatively small, experimentally accessible magnetic field. In doing so, they also witnesses the Schwinger effect in action: producing the analogue of electron-positron pairs in this quantum system.

Graphene has many fascinating properties, but one of them is a unique electronic band structure. There are conduction bands and valence bands, and they can overlap with zero band gap, enabling both holes and electrons to emerge and flow.

Graphene is an odd material in a lot of ways, and one of those ways is that sheets of it behave effectively as a two-dimensional structure. By reducing the number of (effective) dimensions, many degrees of freedom present in three-dimensional materials are taken away, leaving far fewer options for the quantum particles inside, as well as reducing the set of quantum states available for them to occupy.

Leveraging a graphene-based structure known as a superlattice where multiple layers of materials create periodic structures the authors of this study applied an electric field and induced the very behavior described above: where electrons from not just the highest partially-occupied energy state flow as part of the materials conduction, but where electrons from lower, completely filled bands join the flow as well.

Once this occurs, a lot of exotic behaviors arise in this material, but one was seen for the first time ever: the Schwinger effect. Instead of producing electrons and positrons, it produced electrons and the condensed-matter analogue of positrons: holes, where a missing electron in a lattice flows in the opposite directions to the electron flow. The only way to explain the observed currents were with this additional process of spontaneous production of electrons and holes, and the details of the process agreed with Schwingers predictions from all the way back in 1951.

Atomic and molecular configurations come in a near-infinite number of possible combinations, but the specific combinations found in any material determine its properties. Graphene, which is an individual, single-atom sheet of the material shown here, is the hardest material known to humanity, and in pairs-of-sheets it can create a type of material known as a superlattice, with many intricate and counterintuitive properties.

There are many ways of studying the Universe, and quantum analogue systems where the same mathematics that describes an otherwise inaccessible physical regime applies to a system that can be created and studied in a laboratory are some of the most powerful probes we have of exotic physics. Its very difficult to foresee how the Schwinger effect could be tested in its pure form, but thanks to the extreme properties of graphene, including its ability to withstand spectacularly large electric fields and currents, it arose for the very first time in any form: in this particular quantum system. As coauthor Dr. Roshan Krishna Kumar put it:

When we first saw the spectacular characteristics of our superlattice devices, we thought wow it could be some sort of new superconductivity. Although the response closely resembles those routinely observed in superconductors, we soon found that the puzzling behavior was not superconductivity but rather something in the domain of astrophysics and particle physics. It is curious to see such parallels between distant disciplines.

With electrons and positrons (or holes) being created out of literally nothing, just ripped out of the quantum vacuum by electric fields themselves, its yet another way that the Universe demonstrates the seemingly impossible: we really can make something from absolutely nothing!

Originally posted here:

How the Universe really makes something from nothing - Big Think

The researchers show frequencies of spatially separated clocks can be compared more precisely

The researchers show frequencies of spatially separated clocks can be compared more precisely

An experiment carried out by the University of Oxford researchers combines two unique and one can say even mind-boggling discoveries, namely, high-precision atomic clocks and quantum entanglement, to achieve two atomic clocks that are entangled. This means the inherent uncertainty in measuring their frequencies simultaneously is highly reduced.

While this is a proof-of-concept experiment, it has the potential for use in probing dark matter, precision geodesy and other such applications. The two-node network that they build is extendable to more nodes, the researchers write, in an article on this work published in Nature recently.

Atomic clocks grew in accuracy and became so dependable that in 1967, the definition of a second was revised to be the time taken by 9,19,26,31,770 oscillations of a cesium atom. At the start of the 21st century, the cesium clocks that were available were so accurate that they would gain or lose a second only once in about 20 million years. At present, even this record has been broken and there are optical lattice clocks that are so precise that they lose a second only once in 15 billion years. To give some perspective, that is more than the age of the universe, which is 13.8 billion years.

The more mundane uses to which these clocks can be put include accurate time keeping in GPS, or monitoring stuff remotely on Mars.

If you can measure the frequency difference between these two clocks that are in different locations, that opens up a host of applications, says Raghavendra Srinivas, from the Department of Physics, Clarendon Laboratory, University of Oxford, U.K., who is an author of the Nature paper.

Their work is a proof-of-principle demonstration that two strontium atoms separated in space by a small distance, can be pushed into an entangled state so that a comparison of their frequencies becomes more precise. Potential applications of this when extended in space and including more nodes than two, are in studying the space-time variation of the fundamental constants and probing dark matter deep questions in physics.

In quantum physics, entanglement is a weird phenomenon described as a spooky action at a distance by Albert Einstein. Normally, when you consider two systems separated in space that are also independent and you wished to compare some physical attribute of the two systems, you would make separate measurements of that attribute and this would involve a fundamental limitation to how precisely you can compare the two for two separate measurements have to be made.

On the other hand, if the two were entangled, it is a way of saying that their physical attributes, say spin, or in this case, the frequency, vary in tandem. Measuring the attribute on one system, tells you about the other system. This in turn improves the precision of the measurement to the ultimate limit allowed by quantum theory.

Quantum networks of this kind have been demonstrated earlier, but this is the first demonstration of quantum entanglement of optical atomic clocks.

Dr. Srinivas says, The key development here is that we could improve the fidelity and the rate of this remote entanglement to the point where its actually useful for other applications, like in this clock experiment.

For their demonstration, the researchers used strontium atoms for the ease in generating remote entanglement. They plan to try this with better clocks such as those that use calcium.

We showed that you can now generate remote entanglement in a practical way. At some point, it might be useful for state-of-the art systems, says Dr. Srinivas.

See the rest here:

Using spooky action at a distance to link atomic clocks - The Hindu