Category Archives: Quantum Physics

Quantum gravity has fascinated scientists for over a century. The term refers to any theory that seeks to describe gravity in the regimes in which quantum effects cannot be disregarded. Scientists have proposed string theory, loop quantum gravity, and many other theories, but none has achieved universal recognition or been confirmed by the evidence. In that sense, when we speak about quantum gravity, we are speaking not about any single theory, but about one of the great unsolved scientific problems. According to ScitechDaily, a new theory has emerged to compete with these research programs, and it is one that many people will instinctively understand: the universe is pixelated.

ScitechDaily suggests that as digital images become more pixelated the closer you zoom into them, the universe may have a similar structure. Rana Adhikari is one of many scientists who believe that the universe is not perfectly smooth, but is made up of infinitesimally small, discrete units. These spacetime pixels are so small that if they were enlarged to the size of grains of sand, then atoms would become as large as galaxies.

If scientists can find evidence of pixelation, it will be a predictor of quantum gravity. Quantum gravity is important because it unifies two types of physics: the physics of Newton and Einstein, with the physics of Niels Bohr, Erwin Schrdinger, Werner Heisenberg, Max Born and others. It is about bringing together the physics of mass structures, such as the solar system, which are governed by general relativity, with the physics of the very small, which is governed by quantum physics.For many scientists, there has always been a feeling of unease at the fact that there is no unifying principle that brings these two together. If gravity can be quantized, then that great problem is solved and this uneasy state of affairs comes to an end.

Although many people get the impression that these two parts of physics cannot be reconciled, this is in fact not true. There is ample evidence that quantum mechanics exists on this planet, and that alone is evidence of consistency. The problem for many scientists comes when questions around black holes arise, and when they are asked to explain the two in terms o a unified framework in very short distance scales.

This problem has proved so challenging that many scientists do not believe that it can be solved in the next generation. This has not prevented scientists from looking for ways to find evidence of quantum gravity, around black holes, or the early universe, or by using the famed LIGO gravitational wave interferometer.

Yet, there still has not been any evidence of quantum gravity, The absence of evidence is not the evidence of absence. We know from first principles that quantum gravity exists. Indeed, this is also a philosophical problem about the nature of science. Although the Science for Dummies version of what science is about, highlights the importance of evidence, often, there are technological or financial, or other barriers to finding evidence. For example, until LIGO detected gravitational waves in 2016, there was no evidence of them, even though Einsteins work told us that there should be such evidence. A century passed without anything to prove Einstein right.

A new project funded by the Heising-Simon Foundation, and headed by Kathryn Zurek, is attempting to find the evidence that science has been sorely awaiting. Tasked with finding evidence of quantum gravity, the Quantum gRavity and Its Observational Signatures (QuRIOS) is composed of a medley of complimentary talents. There are string theorists, who understand the formal tools of the subject, but typically have no experimental expertise, and particle theorists and model builders, who have a great understanding of experimental design, but little understanding of quantum gravitys formal tools.

Zurek is aware that mainstream science does not believe that you can look for observable features of quantum gravity. This has not dissuaded her or her team. She believes that unless we can link quantum gravity with the world we live in, we will not be able to make any meaningful advances. Observational signatures bring theorists together and allow for more concrete progress to be made.

Zurek and Adhikari will work together in order to design an experiment, the Gravity from Quantum, Entanglement of Space-Time (GQuEST), using tabletop instruments, which, it is hoped, will detect, not so much discrete spacetime pixels, but the connections between them that lead to observable signatures.

The process, akin to tuning an old television set, could bring us closer to observable signatures. The team understands that there are no guarantees. At this stage, what they have is an idea, and it could turn out to be a very bad idea, but the point of science is to experiment, even at the risk of falsifying theories, in the quest for robust theories of how our world works. Truth itself is provisional, in the scientific world. Scientists exist in a perpetual state of experimentation.

Excerpt from:

Quantum Gravity And The Search For A Unified Physics - Science 2.0

PROVIDENCE, R.I. [Brown University] Scientists understand quite well how temperature affects electrical conductance in most everyday metals like copper or silver. But in recent years, researchers have turned their attention to a class of materials that do not seem to follow the traditional electrical rules. Understanding these so-called strange metals could provide fundamental insights into the quantum world, and potentially help scientists understand strange phenomena like high-temperature superconductivity.

Now, a research team co-led by a Brown University physicist has added a new discovery to the strange metal mix. In research published in the journal Nature, the team found strange metal behavior in a material in which electrical charge is carried not by electrons, but by more wave-like entities called Cooper pairs.

While electrons belong to a class of particles called fermions, Cooper pairs act as bosons, which follow very different rules from fermions. This is the first time strange metal behavior has been seen in a bosonic system, and researchers are hopeful that the discovery might be helpful in finding an explanation for how strange metals work something that has eluded scientists for decades.

We have these two fundamentally different types of particles whose behaviors converge around a mystery, said Jim Valles, a professor of physics at Brown and the studys corresponding author. What this says is that any theory to explain strange metal behavior cant be specific to either type of particle. It needs to be more fundamental than that.

Strange metal behavior was first discovered around 30 years ago in a class of materials called cuprates. These copper-oxide materials are most famous for being high-temperature superconductors, meaning they conduct electricity with zero resistance at temperatures far above that of normal superconductors. But even at temperatures above the critical temperature for superconductivity, cuprates act strangely compared to other metals.

As their temperature increases, cuprates resistance increases in a strictly linear fashion. In normal metals, the resistance increases only so far, becoming constant at high temperatures in accord with what's known as Fermi liquid theory. Resistance arises when electrons flowing in a metal bang into the metals vibrating atomic structure, causing them to scatter. Fermi-liquid theory sets a maximum rate at which electron scattering can occur. But strange metals dont follow the Fermi-liquid rules, and no one is sure how they work. What scientists do know is that the temperature-resistance relationship in strange metals appears to be related to two fundamental constants of nature: Boltzmanns constant, which represents the energy produced by random thermal motion, and Plancks constant, which relates to the energy of a photon (a particle of light).

To try to understand whats happening in these strange metals, people have applied mathematical approaches similar to those used to understand black holes, Valles said. So theres some very fundamental physics happening in these materials.

In recent years, Valles and his colleagues have been studying electrical activity in which the charge carriers are not electrons. In 1952, Nobel Laureate Leon Cooper, now a Brown professor emeritus of physics, discovered that in normal superconductors (not the high-temperature kind discovered later), electrons team up to form Cooper pairs, which can glide through an atomic lattice with no resistance. Despite being formed by two electrons, which are fermions, Cooper pairs can act as bosons.

Fermion and boson systems usually behave very differently, Valles said. Unlike individual fermions, bosons are allowed to share the same quantum state, which means they can move collectively like water molecules in the ripples of a wave.

In 2019, Valles and his colleagues showed that Cooper pair bosons can produce metallic behavior, meaning they can conduct electricity with some amount of resistance. That in itself was a surprising finding, the researchers say, because elements of quantum theory suggested that the phenomenon shouldnt be possible. For this latest research, the team wanted to see if bosonic Cooper-pair metals were also strange metals.

The team used a cuprate material called yttrium barium copper oxide patterned with tiny holes that induce the Cooper-pair metallic state. The team cooled the material down to just above its superconducting temperature to observe changes in its conductance. They found, like fermionic strange metals, a Cooper-pair metal conductance that is linear with temperature.

The researchers say this new discovery will give theorists something new to chew on as they try to understand strange metal behavior.

Its been a challenge for theoreticians to come up with an explanation for what we see in strange metals, Valles said. Our work shows that if youre going to model charge transport in strange metals, that model must apply to both fermions and bosons even though these types of particles follow fundamentally different rules.

Ultimately, a theory of strange metals could have massive implications. Strange metal behavior could hold the key to understanding high-temperature superconductivity, which has vast potential for things like lossless power grids and quantum computers. And because strange metal behavior seems to be related to fundamental constants of the universe, understanding their behavior could shed light on basic truths of how the physical world works.

Go here to read the rest:

Newly discovered type of 'strange metal' could lead to deep insights - Brown University

A new study aims to solve Stephen Hawkings black hole information paradox and contrast the black hole fuzzball or wormhole debate. Credit: Shree Luitel | Lantern Reporter

A Dec. 28, 2021, study aims to solve theoretical physicist Stephen Hawkings black hole information paradox and end the black hole fuzzball or wormhole debate.

Researchers at Ohio State have found that string theory, which states that particles at their smallest are made of vibrating strings that can stretch within a black hole, might be the answer to Hawkings paradox.

Samir Mathur, professor of physics at Ohio State and lead author of the study, said this suggests that the information paradox is better explained by what he calls the fuzzball theory along with string theory.

The black hole information paradox arises from Hawkings conclusion that information that enters a black hole can never leave.

Madhur Mehta, a Ph.D. candidate in physics and a researcher on the study, said any information captured within a black hole vanishes at the end of the holes life. However, this theory violates quantum mechanics.

Eventually, as the black hole starts to evaporate, it will collapse and vanish. Hence, the information is lost, Mehta said. However, quantum mechanics says that information is always preserved in the universe, and this gives rise to the information paradox.

Such a paradox threatens not only quantum mechanics, but all of physics.

Mathur said this conclusion poses a significant issue to scientists because quantum mechanics is essential to physics.

If black holes are going to destroy quantum mechanics, then we have lost the basic pillar of physics, Mathur said.

Physicists tried to reconcile Hawkings conclusions with what is called the wormhole theory, which states that gravity forces information to the black holes center until it emerges at another point in space.

Mathur said the study found this to be inconsistent with visible physics. Rather, when using string theory, the researchers found radiation emitted by black holes comes from near the horizon, its edge, rather than the center.

When we did try to make a black hole from string theory, we found that gravity did not end up pulling everything to the center, Mathur said. But these particles get stretched into these strings and fluff up like a big ball of strings that fills up the entirety of the black hole.

Mathur said rather than go through a wormhole, the particles captured by a black hole stretch out in a ball of these strings. This explains why radiation is detected near the black holes edge rather than its center.

Mathur said there have been many possible explanations to the information paradox, but the study heavily supported the fuzzball theory.

People in the string theory community looked for many different solutions to the information paradox, Mathur said. However, in every case, the fuzzball theory just became more and more confirmed.

This finding will not only be used to explain the information paradox, Mehta said, but will help researchers explain other phenomena.

Mehta said this study could resolve the unknown reason for the expansion of the universe at an accelerated rate.

We are trying to use ideas from the fuzzballs and apply it to the cosmological models, and try to understand how fuzzballs could lead to a solution to dark energy, Mehta said.

See original here:

Ohio State study finds string theory may be solution to Stephen Hawking's black hole information paradox - OSU - The Lantern

Swami Vivekanandas insemination of Vedantic thoughts may have influenced the development of quantum physics and modern-day cosmology. I hope to prove that to my readers by the end of this blog. While many civilizations and their achievements have influenced science, but few are as dramatic as that of Vedanta. This was the first record of intermingling of a ten thousand old philosophy with modern science. Science does not always progress through reductionism by getting things proved in the laboratory! Einsteins concepts of relativity and bending of light waves were established decades after he enunciated the theory. Tesla dreamt of an alternate current that is probably the number one ingredient that runs present civilization on this planet. He did not work in a laboratory to develop it.

The biggest names in science during Swami Vivekanandas time listened to and respected him, including Lord Kelvin and Tesla. On 1st Feb 1896, Swamiji wrote about his interaction with Nicholas Tesla Mr. Tesla was charmed to hear about the Vedantic Prana, Akasha & the Kalpas, which according to him, are the only theories modern science can entertain. He further stated, what we call matter does not exist at all; it is only a certain state of force It took science another decade to accept the fact that only energy exists. The matter is only a form of energy. Prana (Energy) is the only existence. Vivekananda as explained in his book Raja Yoga clearly states that it is vibration that started in the initial dormant form of energy that led to the creation of our visible universe. Almost seventy years later Carl Sagan the famous astronomer conceded that the whole concept of big bang and periodically expanding and contracting universe came from the Vedantic concept of Kalpas.

Just like a modern-day scientist awakening from deep meditation below an old peepul tree beside a stream near Almora (Uttarakhand, India), he jotted down his vision as to how the universe is created. He wrote, the scheme of the universe of both micro-world and macro-world are built on the same plan. Of course, as we all know that the macroworld of giant stars, planets, galaxies, and black holes is totally different from the microworld of quantum fuzziness, but modern-day physics is working on how these two can be connected. Einstein died having failed to create a Theory of Everything-that will bring together many such discordant realities. The string theory which is yet to be proved answers some of these. This theory hypothesizes the presence of small strings at the end point of creation. All matter is created by vibration of such strings. When confronted with the realities of quantum mechanics, even Einstein protested that the universe behaves in this weird way saying, God does not play dice. In other words, if you are sitting in Alpha Centauri our neighboring triple star system and I need to communicate with you based on Einsteinian concepts since light is the fastest medium it will take four and half year to send you any message! However, we know that an entangled electron can know the position of its entangled pair in the other end of the universe. As Einstein suggested, if it did communicate using light, that would take millions of light years for that communication to reach. But this is instantaneous. Experiment has shown this phenomenon even at a macro level in entangled entities.

The truth is that as Swami Vivekananda factually demonstrated to one of his favorite disciples that the universe is a limitless form of energy vibrating. Therefore, all we see as matter is only vibrations that our brain deciphers as reality: chairs, tables, etc. Today a group of neuroscientists calls that controlled hallucination. Yes, our brain converts the reality that is the timeless foam of vibration into the matter we comprehend in our daily lives. Imagine this was what Swami Ji mentioned almost a century back when modern science was still obsessed with the matter being made of an indivisible unit called atoms where electrons rotated around the nucleus as planets revolve around the sun.

It is indeed astounding that some of the current thoughts in modern physics and cosmology are in consonance to what he said a century back Absolute is manifesting itself as many through the veil of Time, space and causation. Time is entirely a dependent existence; it changes with every change of our mind. ..So with space. it cannot exist separate from anything else. So, with causation. John Archibald Wheeler the American physicist put it is more scientific terms, Nothing exists until observed. Thus, as Vedanta contends reality is created by us the observer.

From Einstein to David Bohm, everyone was influenced by such Vedantic thoughts that we know from their own writing. Thus, while we do not want to trivialize the achievements of great minds in the twentieth century that gave us a proper understanding of the universe, we live in. It is true that using meditation and powerful yogic practices, giants like Buddha and Swami Vivekananda had a peek into the truth of creation way before even science thought in those lines.

The question is, how? Richard Davidson, a professor ofpsychologyandpsychiatryat theUniversity of WisconsinMadison,has studied the brains of hundreds of meditators. People with hundreds of hours of meditation can completely change their brains. Everything is possible, from decreasing aging to growing your brain to keeping you healthy. As Swami Vivekananda himself explains, Yet, just as by the telescope and the microscope we can increase the scope of our vision; similarly, we can by Yoga bring ourselves to the state of the vibration of another plane, and thus enable ourselves to see what is going on there.

Views expressed above are the author's own.

END OF ARTICLE

See the original post:

Did Vedantic thoughts influence Twentieth Century Physics? A perspective on Swami Vivekananda - The Times of India Blog

January 7, 2022

Professor Cheng Chin has received the 2122 Marian and Stuart Rice Research Award, a Divisional honor that provides $100,000 for intellectually exciting and innovative research ventures that enable new research directions.

Chin joined the University of Chicago in 2005 and has been a full professor in the Department of Physics, the Enrico Fermi Institute, and the James Franck Institute since 2012. He is a pioneer in using ultracold atoms to study the quantum phenomena that underlie the behavior of other particles in the universe.

I am very excited about this generous support from the PSD, and especially from Stuart Rice, he said. The fund will enable a brand new research line into molecular quantum matter, on which my students and I are very excited to begin.

Chin's research team explores molecules and their reactions at the extremely low temperatures of 10 billionth of a degree above absolute zero. Molecules at such temperatures condense into a single quantum state with new forms of matter and reactions yet unknown to the molecular physics community. Their proposed experimental research will pursue the emergence of novel molecular quantum matter and quantum reactions.

The first research goal, Chin said, is to characterize these ultracold molecules and investigate their fundamental properties. They are predicted to form novel phases of chemical matter unlike their higher temperature counterparts.

Another goal is to study the conjectured regime of "quantum super chemistry." Similar to superconductors where electrons form super-current that flows without resistance, these Bose condensed molecules can react and interact without friction and energy cost. Chin proposes to study some of the fundamental chemical processes: composition, decomposition, replacement, and dissociation in the quantum super chemistry regime.

The great hope is that these studies will reveal new guiding principles and exciting prospects to control reaction pathways, he said. Novel applications might include inducing chemical reactions without energy dissipation, as in superconducting current; stimulated production of molecules, as in laser operation; and quantum information processing with molecular qubits.

Chin said the award will be used to upgrade the cold atom and molecule experiment to enhance the capability to manipulate and image molecules. Funds will be used to acquire experimental equipment for the proposed research as well as to attract students in physics and chemistry to perform the experiments.

The proposed research builds on work that has shaped and defined atomic, molecular, and optical physics. In 2011, Chin was recognized as the first physicist to observe the Efimov molecules at the ultracold temperature. More recently, in 2019, he designed an experiment that demonstrated a novel way to simulate physics in curved spacetimes, observing emissions that offer a view into the quantum origin of Unruh radiation. Last year, the discovery that multiple molecules can be brought at once into a single quantum state came from Chin labaccomplishing one of the most important goals in quantum physics.

The Marian and Stuart Rice Research Award was established by the family of Stuart Alan Rice, the Frank P. Hixon Distinguished Service Professor Emeritus in Chemistry and former chairman of the Department of Chemistry and dean of the Physical Sciences (1981-1995). It is awarded annually to promote new directions of research in the physical and mathematical sciences at the University of Chicago.

Awards, Faculty

See original here:

Cheng Chin receives '21'22 Marian and Stuart Rice Research Award | News | Physical Sciences Division | The University of Chicago - UChicago News

Heres a brain teaser for you: scientists are suggesting spacetime may be made out of individual spacetime pixels, instead of being smooth and continuous like it seems.

Rana Adhikari, a professor of physics at Caltech, suggested in a new press blurb that these pixels would be so small that if you were to enlarge things so that it becomes the size of a grain of sand, then atoms would be as large as galaxies.

Adhikaris goal is to reconcile the conventional laws of physics, as determined by general relativity, with the more mysterious world of quantum physics.

Its a seriously mind-bending theory that attempts to explain whether gravity can actually be split up into its individual components, a question that has been keeping quantum physicists up at night for a long time.

Sometimes there is a misinterpretation in science communication that implies quantum mechanics and gravity are irreconcilable, said Cliff Cheung, a Caltech professor of theoretical physics whos working with Adhikari, in the statement. But we know from experiments that we can do quantum mechanics on this planet, which has gravity, so clearly they are consistent.

The devil, as always, is in the detail.

The problems come up when you ask subtle questions about black holes or try to merge the theories at very short distance scales, Cheung added.

In other words, if you were to zoom in on spacetime, would you also find individual photons, which make up light, according to the laws of quantum mechanics? Or would it be a continuous spectrum?

Some scientists suggest individual hypothetical gravitons could make up gravity on the smallest scale. Gravitons are a component of string theory that would resonate at a particular frequency.

But on an even smaller scale than that, scientists are still scratching their heads as to how to unify the laws of general relativity and quantum physics.

If I drop my coffee mug and it falls, Id like to think thats gravity, Adhikari quipped. But, in the same way that temperature is not real but describes how a bunch of molecules are vibrating, spacetime might not be a real thing.

The same may go for spacetime.

It may be that something that arises out of the pixelation of spacetime has just been given the name gravity because we dont yet understand what the guts of spacetime are, he added.

READ MORE: Is Space Pixelated? The Quest for Quantum Gravity [California Institute of Technology]

More on quantum physics: Scientist Claims That Aliens May Be Communicating via Starlight

Care about supporting clean energy adoption? Find out how much money (and planet!) you could save by switching to solar power at UnderstandSolar.com. By signing up through this link, Futurism.com may receive a small commission.

Read more here:

Scientists Say the Universe Itself May Be "Pixelated" - Futurism

Jody DruceNews Editor

Some staff in the School of Physics are to call for the Erwin Schrdinger lecture theatre to be renamed in light of revelations about the physicists abuse of young women and girls.

Two staff members in the School confirmed to The University Times that a meeting will be held to discuss the possibility of renaming the theatre, after an Irish Times article published in December detailed Schrdingers record as a sexual predator. The meeting was supposed to be held today but was postponed.

A petition published last month calling for Schrdingers removal from the School of Physics lecture theatres name, has garnered 51 signatures. The petition is being shared among staff in the school, but it was not created by a staff member.

The physicist, known for his contributions to quantum theory, worked in Trinity for nearly 20 years and became a naturalised Irish citizen.

The article names three girls who were teenagers or pre-adolescents when Schrdinger became infatuated with them.

According to the 2012 biography Erwin Schrdinger and the Quantum Revolution by John Gribbin, which is cited in the article, Schrdinger groomed a 14-year-old girl named Itha Junger after he became her mathematics tutor. Schrdinger, then in his mid forties, wrote that he fell in love with the girl and admitted to having intercourse with her when she was 17.

In the same year, Junger became pregnant and had a disastrous abortion that left her sterile according to the Irish Times. The relationship ended soon after.

In Schrdinger, Life and Thought, Walter Moore describes how Schrdinger became infatuated with a 12-year-old girl named Barbara. While Schrdinger agreed not to pursue the child after one of her family members raised concerns, he wrote in his diaries that she was among the unrequited loves of his life.

Moore wrote that the physicists attitude towards women was essentially that of a male supremacist.

The petition said: It seems in bad taste that a modern college such as Trinity one that holds lectures to both men and women, one that (hopefully) rejects the abuse of women, of young girls or, indeed, of anyone would honour this man with an entire building.

It added: The School of Physics is, and always should be, a welcoming, inclusive place of learning. Who we choose to honour our places of study with should reflect that.

We can acknowledge the great mark Schrodinger has left on science through our study, and this petition does not wish to diminish the impact his lectures or ideas had in physics.

If you have been affected by, or would like to discuss issues concerning sexual assault or non-consensual behaviour, you can contact the Welfare Officer of Trinity College Dublin Students Union by emailing [emailprotected] Emergency appointments with the Student Counselling Service are also available. You can phone Niteline, the student listening service, every night of term from 9pm2:30am on 1800 793 793, or the Samaritans at any time on 116 123. The Dublin Rape Crisis Centre can be reached at 1800 778 888.

Follow this link:

Physics Staff to Call for Schrdinger Theatre to be Renamed - The University Times

The last star will slowly cool and fade away. With its passing, the universe will become once more a void, without light or life or meaning. So warned the physicist Brian Cox in the recent BBC series Universe. The fading of that last star will only be the beginning of an infinitely long, dark epoch. All matter will eventually be consumed by monstrous black holes, which in their turn will evaporate away into the dimmest glimmers of light. Space will expand ever outwards until even that dim light becomes too spread out to interact. Activity will cease.

Or will it? Strangely enough, some cosmologists believe a previous, cold dark empty universe like the one which lies in our far future could have been the source of our very own Big Bang.

But before we get to that, lets take a look at how material physical matter first came about. If we are aiming to explain the origins of stable matter made of atoms or molecules, there was certainly none of that around at the Big Bang nor for hundreds of thousands of years afterwards. We do in fact have a pretty detailed understanding of how the first atoms formed out of simpler particles once conditions cooled down enough for complex matter to be stable, and how these atoms were later fused into heavier elements inside stars. But that understanding doesnt address the question of whether something came from nothing.

So lets think further back. The first long-lived matter particles of any kind were protons and neutrons, which together make up the atomic nucleus. These came into existence around one ten-thousandth of a second after the Big Bang. Before that point, there was really no material in any familiar sense of the word. But physics lets us keep on tracing the timeline backwards to physical processes which predate any stable matter.

This takes us to the so-called grand unified epoch. By now, we are well into the realm of speculative physics, as we cant produce enough energy in our experiments to probe the sort of processes that were going on at the time. But a plausible hypothesis is that the physical world was made up of a soup of short-lived elementary particles including quarks, the building blocks of protons and neutrons. There was both matter and antimatter in roughly equal quantities: each type of matter particle, such as the quark, has an antimatter mirror image companion, which is near identical to itself, differing only in one aspect. However, matter and antimatter annihilate in a flash of energy when they meet, meaning these particles were constantly created and destroyed.

But how did these particles come to exist in the first place? Quantum field theory tells us that even a vacuum, supposedly corresponding to empty spacetime, is full of physical activity in the form of energy fluctuations. These fluctuations can give rise to particles popping out, only to be disappear shortly after. This may sound like a mathematical quirk rather than real physics, but such particles have been spotted in countless experiments.

The spacetime vacuum state is seething with particles constantly being created and destroyed, apparently out of nothing. But perhaps all this really tells us is that the quantum vacuum is (despite its name) a something rather than a nothing. The philosopher David Albert has memorably criticised accounts of the Big Bang which promise to get something from nothing in this way.

Suppose we ask: where did spacetime itself arise from? Then we can go on turning the clock yet further back, into the truly ancient Planck epoch a period so early in the universes history that our best theories of physics break down. This era occurred only one ten-millionth of a trillionth of a trillionth of a trillionth of a second after the Big Bang. At this point, space and time themselves became subject to quantum fluctuations. Physicists ordinarily work separately with quantum mechanics, which rules the microworld of particles, and with general relativity, which applies on large, cosmic scales. But to truly understand the Planck epoch, we need a complete theory of quantum gravity, merging the two.

We still dont have a perfect theory of quantum gravity, but there are attempts like string theory and loop quantum gravity. In these attempts, ordinary space and time are typically seen as emergent, like the waves on the surface of a deep ocean. What we experience as space and time are the product of quantum processes operating at a deeper, microscopic level processes that dont make much sense to us as creatures rooted in the macroscopic world.

In the Planck epoch, our ordinary understanding of space and time breaks down, so we cant any longer rely on our ordinary understanding of cause and effect either. Despite this, all candidate theories of quantum gravity describe something physical that was going on in the Planck epoch some quantum precursor of ordinary space and time. But where did that come from?

Even if causality no longer applies in any ordinary fashion, it might still be possible to explain one component of the Planck-epoch universe in terms of another. Unfortunately, by now even our best physics fails completely to provide answers. Until we make further progress towards a theory of everything, we wont be able to give any definitive answer. The most we can say with confidence at this stage is that physics has so far found no confirmed instances of something arising from nothing.

Paradoxical though it might seem, a total absence of matter might have managed to give rise to all the matter we see around us in our universe

To truly answer the question of how something could arise from nothing, we would need to explain the quantum state of the entire universe at the beginning of the Planck epoch. All attempts to do this remain highly speculative. Some of them appeal to supernatural forces like a designer. But other candidate explanations remain within the realm of physics such as a multiverse, which contains an infinite number of parallel universes, or cyclical models of the universe, being born and reborn again.

The 2020 Nobel Prize-winning physicist Roger Penrose has proposed one intriguing but controversial model for a cyclical universe dubbed conformal cyclic cosmology. Penrose was inspired by an interesting mathematical connection between a very hot, dense, small state of the universe as it was at the Big Bang and an extremely cold, empty, expanded state of the universe as it will be in the far future. His radical theory to explain this correspondence is that those states become mathematically identical when taken to their limits. Paradoxical though it might seem, a total absence of matter might have managed to give rise to all the matter we see around us in our universe.

In this view, the Big Bang arises from an almost nothing. Thats whats left over when all the matter in a universe has been consumed into black holes, which have in turn boiled away into photons lost in a void. The whole universe thus arises from something that viewed from another physical perspective is as close as one can get to nothing at all. But that nothing is still a kind of something. It is still a physical universe, however empty.

How can the very same state be a cold, empty universe from one perspective and a hot dense universe from another? The answer lies in a complex mathematical procedure called conformal rescaling, a geometrical transformation which in effect alters the size of an object but leaves its shape unchanged.

Penrose showed how the cold dense state and the hot dense state could be related by such rescaling so that they match with respect to the shapes of their spacetimes although not to their sizes. It is, admittedly, difficult to grasp how two objects can be identical in this way when they have different sizes but Penrose argues size as a concept ceases to make sense in such extreme physical environments.

In conformal cyclic cosmology, the direction of explanation goes from old and cold to young and hot: the hot dense state exists because of the cold empty state. But this because is not the familiar one of a cause followed in time by its effect. It is not only size that ceases to be relevant in these extreme states: time does too. The cold dense state and the hot dense state are in effect located on different timelines. The cold empty state would continue on forever from the perspective of an observer in its own temporal geometry, but the hot dense state it gives rise to effectively inhabits a new timeline all its own.

It may help to understand the hot dense state as produced from the cold empty state in some non-causal way. Perhaps we should say that the hot dense state emerges from, or is grounded in, or realised by the cold, empty state. These are distinctively metaphysical ideas which have been explored by philosophers of science extensively, especially in the context of quantum gravity where ordinary cause and effect seem to break down. At the limits of our knowledge, physics and philosophy become hard to disentangle.

Conformal cyclic cosmology offers some detailed, albeit speculative, answers to the question of where our Big Bang came from. But even if Penroses vision is vindicated by the future progress of cosmology, we might think that we still wouldnt have answered a deeper philosophical question a question about where physical reality itself came from. How did the whole system of cycles come about?Then we finally end up with the pure question of why there is something rather than nothing one of the biggest questions of metaphysics.

But our focus here is on explanations which remain within the realm of physics. There are three broad options to the deeper question of how the cycles began. It could have no physical explanation at all. Or there could be endlessly repeating cycles, each a universe in its own right, with the initial quantum state of each universe explained by some feature of the universe before. Or there could be one single cycle, and one single repeating universe, with the beginning of that cycle explained by some feature of its own end. The latter two approaches avoid the need for any uncaused events and this gives them a distinctive appeal. Nothing would be left unexplained by physics.

Penrose envisages a sequence of endless new cycles for reasons partly linked to his own preferred interpretation of quantum theory. In quantum mechanics, a physical system exists in a superposition of many different states at the same time, and only picks one randomly, when we measure it. For Penrose, each cycle involves random quantum events turning out a different way meaning each cycle will differ from those before and after it. This is actually good news for experimental physicists, because it might allow us to glimpse the old universe that gave rise to ours through faint traces, or anomalies, in the leftover radiation from the Big Bang seen by the Planck satellite.

Penrose and his collaborators believe they may have spotted these traces already, attributing patterns in the Planck data to radiation from supermassive black holes in the previous universe. However, their claimed observations have been challenged by other physicists and the jury remains out.

Endless new cycles are key to Penroses own vision. But there is a natural way to convert conformal cyclic cosmology from a multi-cycle to a one-cycle form. Then physical reality consists in a single cycling around through the Big Bang to a maximally empty state in the far future and then around again to the very same Big Bang, giving rise to the very same universe all over again.

Some people believe parallel universes may be observable in cosmological data, as imprints caused by another universe colliding with ours

This latter possibility is consistent with another interpretation of quantum mechanics, dubbed the many-worlds interpretation. The many-worlds interpretation tells us that each time we measure a system that is in superposition, this measurement doesnt randomly select a state. Instead, the measurement result we see is just one possibility the one that plays out in our own universe. The other measurement results all play out in other universes in a multiverse, effectively cut off from our own. So no matter how small the chance of something occurring, if it has a non-zero chance then it occurs in some quantum parallel world. There are people just like you out there in other worlds who have won the lottery, or have been swept up into the clouds by a freak typhoon, or have spontaneously ignited, or have done all three simultaneously.

Some people believe such parallel universes may also be observable in cosmological data, as imprints caused by another universe colliding with ours.

Many-worlds quantum theory gives a new twist on conformal cyclic cosmology, though not one that Penrose agrees with. Our Big Bang might be the rebirth of one single quantum multiverse, containing infinitely many different universes all occurring together. Everything possible happens then it happens again and again and again.

For a philosopher of science, Penroses vision is fascinating. It opens up new possibilities for explaining the Big Bang, taking our explanations beyond ordinary cause and effect. It is therefore a great test case for exploring the different ways physics can explain our world. It deserves more attention from philosophers.

For a lover of myth, Penroses vision is beautiful. In Penroses preferred multi-cycle form, it promises endless new worlds born from the ashes of their ancestors. In its one-cycle form, it is a striking modern re-invocation of the ancient idea of the ouroboros, or world-serpent. In Norse mythology, the serpent Jrmungandr is a child of Loki, a clever trickster, and the giant Angrboda. Jrmungandr consumes its own tail, and the circle created sustains the balance of the world. But the ouroboros myth has been documented all over the world including as far back as ancient Egypt.

The ouroboros of the one cyclic universe is majestic indeed. It contains within its belly our own universe, as well as every one of the weird and wonderful alternative possible universes allowed by quantum physics and at the point where its head meets its tail, it is completely empty yet also coursing with energy at temperatures of a hundred thousand million billion trillion degrees Celsius. Even Loki, the shapeshifter, would be impressed.

View post:

How could the Big Bang arise from nothing? - TechCentral

Winter/Spring2022Virtual Science Inquiry Lecture SeriesExplore cutting-edge science topics, their latest developments, and their relevance to society. Sponsored by the Gallatin Valley Friends of the Sciences, and co-sponsored by the non-profit community service organization Hopa Mountain andMuseum of the Rockies, talks for the 2022 winter/spring serieswill be presented virtually via the Zoom video conferencing platformon Wednesday evenings at 7 pm, followed by a brief question-and-answer period using the Zoom chat function.

Quantum Materials and the MonArk Quantum FoundryHow does quantum mechanics work, and how can it be applied to practical, everyday use?Dr. Yves Idzerda, MSU Professor of Physics and Dean of the College of Letters and Science, will discuss the latest advances in quantum technology and how MSUs NSF-funded quantum foundry will research and develop quantum materials and devices that will connect science and industry.

Free and open to the public via Zoom.Visit theGallatin Valley Friends of the Sciences websitefor the Zoom link for this lecture.

Here is the original post:

Science Inquiry Lecture: Quantum Materials and the MonArk Quantum Foundry - Montana State University

Professor Stephen Hawkings final theory on the origin of the universe, which he worked on in collaboration with Professor Thomas Hertog from KU Leuven, was published in 2018 in the Journal of High Energy Physics.

The theory, which was submitted for publication before Hawkings death earlier in 2018, is based on string theory and predicts the universe is finite and far simpler than many current theories about the big bang say.

Professor Hertog, whose work has been supported by the European Research Council, first announced the new theory at a conference at the University of Cambridge in July of 2017, organized on the occasion of Professor Hawkings 75th birthday.

Modern theories of the big bang predict that our local universe came into existence with a brief burst of inflation in other words, a tiny fraction of a second after the big bang itself, the universe expanded at an exponential rate. It is widely believed, however, that once inflation starts, there are regions where it never stops. It is thought that quantum effects can keep inflation going forever in some regions of the universe so that globally, inflation is eternal. The observable part of our universe would then be just a hospitable pocket universe, a region in which inflation has ended and stars and galaxies formed.

The usual theory of eternal inflation predicts that globally our universe is like an infinite fractal, with a mosaic of different pocket universes, separated by an inflating ocean, said Hawking in an interview in 2017. The local laws of physics and chemistry can differ from one pocket universe to another, which together would form a multiverse. But I have never been a fan of the multiverse. If the scale of different universes in the multiverse is large or infinite the theory cant be tested.

In their paper, Hawking and Hertog say this account of eternal inflation as a theory of the big bang is wrong. The problem with the usual account of eternal inflation is that it assumes an existing background universe that evolves according to Einsteins theory of general relativity and treats the quantum effects as small fluctuations around this, said Hertog. However, the dynamics of eternal inflation wipes out the separation between classical and quantum physics. As a consequence, Einsteins theory breaks down in eternal inflation.

We predict that our universe, on the largest scales, is reasonably smooth and globally finite. So it is not a fractal structure, said Hawking.

The theory of eternal inflation that Hawking and Hertog put forward is based on string theory: a branch of theoretical physics that attempts to reconcile gravity and general relativity with quantum physics, in part by describing the fundamental constituents of the universe as tiny vibrating strings. Their approach uses the string theory concept of holography, which postulates that the universe is a large and complex hologram: physical reality in certain 3D spaces can be mathematically reduced to 2D projections on a surface.

Hawking and Hertog developed a variation of this concept of holography to project out the time dimension in eternal inflation. This enabled them to describe eternal inflation without having to rely on Einsteins theory. In the new theory, eternal inflation is reduced to a timeless state defined on a spatial surface at the beginning of time.

When we trace the evolution of our universe backwards in time, at some point we arrive at the threshold of eternal inflation, where our familiar notion of time ceases to have any meaning, said Hertog.

Hawkings earlier no boundary theory predicted that if you go back in time to the beginning of the universe, the universe shrinks and closes off like a sphere, but this new theory represents a step away from the earlier work. Now were saying that there is a boundary in our past, said Hertog.

Hertog and Hawking used their new theory to derive more reliable predictions about the global structure of the universe. They predicted the universe that emerges from eternal inflation on the past boundary is finite and far simpler than the infinite fractal structure predicted by the old theory of eternal inflation.

Their results, if confirmed by further work, would have far-reaching implications for the multiverse paradigm. We are not down to a single, unique universe, but our findings imply a significant reduction of the multiverse, to a much smaller range of possible universes, said Hawking.

This makes the theory more predictive and testable.

Hertog now plans to study the implications of the new theory on smaller scales that are within reach of our space telescopes. He believes that primordial gravitational waves ripples in spacetime generated at the exit from eternal inflation constitute the most promising smoking gun to test the model. The expansion of our universe since the beginning means such gravitational waves would have very long wavelengths, outside the range of the current LIGO detectors. But they might be heard by the planned European space-based gravitational wave observatory, LISA, or seen in future experiments measuring the cosmic microwave background.

Reference: A smooth exit from eternal inflation? by S. W. Hawking and Thomas Hertog, 27 April 2018, Journal of High Energy Physics.DOI: 10.1007/JHEP04(2018)147

Read more from the original source:

Constraining the Multiverse: Stephen Hawkings Final Theory About the Big Bang - SciTechDaily