Category Archives: Quantum Physics

Todays stories include Quantum Theory of Consciousness Challenged to Is Life on Earth the Standard Model for the Universe to The 50 Million-Year-Old Treasures of Fossil Lake, and much more.

What makes the human brain different? Yale study reveals clues What makes the human brain distinct from that of all other animals including even our closest primate relatives? In an analysis of cell types in the prefrontal cortex of four primate species, Yale researchers identified species-specific particularly human-specific features, they report Aug. 25 in the journal Science.

Seven Million Years Ago, the Oldest Known Early Human Was Already Walking, reports The Smithsonian. Analysis of a femur fossil indicates that a key species could already move somewhat like us.

Extraterrestrial Life Is Earth the Standard Model for the Universe? asks The Daily Galaxy. By the end of this century, says astrophysicist Martin Rees, we should be able to ask whether or not we live in a multiverse, and how much variety of the laws of physics its constituent universes display. The answer to this question, says Rees, will determine how we should interpret the biofriendly universe in which we live (sharing it with any aliens with whom we might one day make contact).

Unfathomable Abodes of Life? Water Worlds of the Milky WayBefore life appeared on land some 400 million years ago, all life on Earth including the mind evolved in the sea. Astronomers have recently conjectured that blue exoplanets with endless oceans may be orbiting many of the Milky Ways one trillion stars, reports The Daily Galaxy.

What Drives Galaxies? The Milky Ways Black Hole May Be the Key--What Drives Galaxies? The Milky Ways Black Hole May Be the Key. Supermassive black holes have come to the fore as engines of galactic evolution, but new observations of the Milky Way and its central hole dont yet hang together, reports Quanta.

Quantum theory of consciousness put in doubt by underground experiment, reports Physics World. A controversial theory put forward by physicist Roger Penrose and anesthesiologist Stuart Hameroff that posits consciousness to be a fundamentally quantum-mechanical phenomenon has been challenged by research looking at the role of gravity in the collapse of quantum wavefunctions.

How quantum physicists are looking for life on exoplanets, reports Northeastern University. News@Northeastern spoke to Gregory Fiete, a physics professor at Northeastern, about some of the broad applications of quantum research, from developing renewable energy sources and building more powerful computers, to advancing humanitys quest to discover life beyond the solar system.

The Plan to Look for Life on VenusWithout NASA--A private group of scientists and rocket engineers might be the first to find signs of extraterrestrial life on the second planet from the sun, reports The Daily Beast.

After Millennia of Agricultural Expansion, the World Has Passed Peak Agricultural Land, reports Dr. Hannah Ritchie for Singularity HubHumans have been reshaping the planets land for millennia by clearing wildlands to grow crops and raise livestock. As a result, humans have cleared one-third of the worlds forests and two-thirds of wild grasslands since the end of the last ice age.

The 50 Million-Year-Old Treasures of Fossil Lake In a forbidding Wyoming desert, scientists and fortune hunters search for the surprisingly intact remains of horses and other creatures that lived long ago, reports The Smithsonian..

Drought Exposes Dinosaur Tracks in Texas--The 113-million-year-old footprints were largely made by the carnivorous Acrocanthosaurus, reports The Smithsonian. A severe drought in Texas has revealed 113-million-year-old dinosaur tracks in Dinosaur Valley State Park. The prints are usually covered by the Paluxy Riverthe last time they were visible was in the year 2000, according to BBC News.

Doppelgngers Dont Just Look AlikeThey Also Share DNANew research finds genetic and lifestyle similarities between unrelated pairs of virtual twins, reports the Smithsonian. People with very similar faces also share many of the same genes and lifestyle traits, according to a new paper published Tuesday in the journal Cell Reports.

Shape of human brain has barely changed in past 160,000 years An analysis of fossils suggests changes in the shape of the braincase during human evolution were linked to alterations in the face, rather than changes in the brain itself, reports New Scientist.

Humanity Is Woefully Unprepared for a Major Volcanic Eruption, reports Gizmodo. When the Hunga Tonga-Hunga Haapai volcano erupted in Tonga on January 15, the result was devastation. The eruption literally blew up an island, caused mass flooding in the surrounding areas, coated whole communities in a thick layer of ash, and took out telecommunications for weeks. Yet in that eruption, we got lucky, according to a new commentary article .

Scientists discovered a 5 million-year-old time capsule buried in Antarctica--Its an ice core with bubbles containing remains of ancient Earth atmosphere, reports ZME Science.

When will Chinas population peak? It depends who you ask--Data show the country is facing a demographic crisis, with an aging population and young couples having fewer children, reports Nature.

MIT professor wrongfully accused of spying for China helps make a major discovery Gang Chen, who was cleared after a lengthy DOJ investigation, said he is stepping away from federally funded research because of anxieties around being racially profiled, reports NBC.

Reconstructing ice age diets reveals an unraveling web of lifeWhile about 6% of land mammals have gone extinct in that time, we estimate that more than 50% of mammal food web links have disappeared, said ecologist Evan Fricke, lead author of the study. And the mammals most likely to decline, both in the past and now, are key for mammal food web complexity, reports Rice University.

Why Thinking Hard Wears You OutConcentrating for long periods builds up chemicals that disrupt brain functioning, reports Scientific American.

Tiny Caribbean crustaceans and their bioluminescent mating displays are shining new light on evolution, reports Science. No bigger than a grain of sand, ostracods abound in fresh and saltwater. They are very cute but also sort of bizarrelike a cross between a crab and a tiny spaceship, says Timothy Fallon, an evolutionary biochemist at the University of California (UC), San Diego.

The Biggest Offshore Wind Farm in the World Will Be Fully Online This Month, reports Singularity Hub. A massive offshore wind project has been underway off the coast of England for over four years. Construction of Hornsea One started in January 2018, and generated its first power a year and a half later. Meanwhile, construction of neighboring Hornsea Two got underway, with that site first coming online last December.

Eye movements in REM sleep mimic gazes in the dream world, reports the University of California, San Francisco. When our eyes move during REM sleep, were gazing at things in the dream world our brains have created, according to a new study by researchers at UC San Francisco. The findings shed light not only into how we dream, but also into how our imaginations work.

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What Makes the Human Brain Unique to How Quantum Physicists are Looking for Alien Life (Planet Earth Report) - The Daily Galaxy --Great Discoveries...

In some pockets of space, far beyond the limits of our observations, wrote cosmologist Dan Hooper at the University of Chicago in an email to The Daily Galaxy, referring to the theory of eternal inflation and the inflationary multiverse: the laws of physics could be very different from those we find in our local universe. Different forms of matter could exist, which experience different kinds of forces. In this sense, what we call the laws of physics, instead of being a universal fact of nature, could be an environmental fact, which varies from place to place, or from time to time.

I think I know how the universe was born, said Andrei Linde, Russian-American theoretical physicist and the Harald Trap Friis Professor of Physics at Stanford University. Linde is one of the main authors of the inflationary universe theory, as well as the theory of eternal inflation and inflationary multiverse.

According to quantum models, galaxies like the Milky Way grew from faint wrinkles in the fabric of spacetime. The density of matter in these wrinkles was slightly greater compared to surrounding areas and this difference was magnified during inflation, allowing them to attract even more matter. From these dense primordial seeds grew the cosmic structures we see today. Galaxies are children of random quantum fluctuations produced during the first 10-35 seconds after the birth of the universe, said Linde.

As a result, the universe becomes a multiverse, an eternally growing fractal consisting of exponentially many exponentially large parts, Linde wrote. These parts are so large that for all practical purposes they look like separate universes.

Late one summer night in 1981, while still a junior research fellow at Lebedev Physical Institute in Moscow, Andrei Linde was struck by a revelation. Unable to contain his excitement, he shook awake his wife, Renata Kallosh, and whispered to her in their native Russian, I think I know how the universe was born.

Kallosh, a theoretical physicist herself, muttered some encouraging words and fell back asleep. It wasnt until the next morning that I realized the full impact of what Andrei had told me, recalled Kallosh, now a professor of physics at the Stanford Institute for Theoretical Physics.

Lindes nocturnal eureka moment had to do with a problem in cosmology that he and other theorists, including Stephen Hawking, had struggled with.

A year earlier, a 32-year-old postdoc at SLAC National Accelerator Laboratory named Alan Guth shocked the physics community by proposing a bold modification to the Big Bang theory. According to Guths idea, which he called inflation, our universe erupted from a vacuum-like state and underwent a brief period of faster-than-light expansion. In less than a billionth of a trillionth of a trillionth of a second, space-time doubled more than 60 times from a subatomic speck to a volume many times larger than the observable universe.

Guth envisioned the powerful repulsive force fueling the universes exponential growth as a field of energy flooding space. As the universe unfurled, this inflation field decayed, and its shed energy was transfigured into a fiery bloom of matter and radiation. This pivot, from nothing to something and timelessness to time, marked the beginning of the Big Bang. It also prompted Guth to famously quip that the inflationary universe was the ultimate free lunch.

As theories go, inflation was a beauty. It explained in one fell swoop why the universe is so large, why it was born hot, and why its structure appears to be so flat and uniform over vast distances. There was just one problem it didnt work.

To conclude the unpacking of space-time, Guth borrowed a trick from quantum mechanics called tunneling to allow his inflation field to randomly and instantly skip from a higher, less stable energy state to a lower one, thus bypassing a barrier that could not be scaled by classical physics.

But closer inspection revealed that quantum tunneling caused the inflation field to decay quickly and unevenly, resulting in a universe that was neither flat nor uniform. Aware of the fatal flaw in his theory, Guth wrote at the end of his paper on inflation: I am publishing this paper in the hope that it will encourage others to find some way to avoid the undesirable features of the inflationary scenario.

Linde Answers Guth

Guths plea was answered by Linde, who on that fateful summer night realized that inflation didnt require quantum tunneling to work. Instead, the inflation field could be modeled as a ball rolling down a hill of potential energy that had a very shallow, nearly flat slope. While the ball rolls lazily downhill, the universe is inflating, and as it nears the bottom, inflation slows further and eventually ends. This provided a graceful exit to the inflationary state that was lacking in Guths model and produced a cosmos like the one we observe. To distinguish it from Guths original model while still paying homage to it, Linde dubbed his model new inflation.

Models of Inflation Theory

By the time Linde and Kallosh moved to Stanford in 1990, experiments had begun to catch up with the theory. Space missions were finding temperature variations in the energetic afterglow of the Big Bang called the cosmic microwave background radiation that confirmed a startling prediction made by the latest inflationary models. These updated models went by various names chaotic inflation, eternal inflation, eternal chaotic inflation and many more but they all shared in common the graceful exit that Linde pioneered.

Quantum Fluctuation Fingerprints

Inflation predicted that these quantum fluctuations would leave imprints on the universes background radiation in the form of hotter and colder regions, and this is precisely what two experiments dubbed COBE and WMAP found. After the COBE and WMAP experiments, inflation started to become part of the standard model of cosmology, Shamit Kachru said.

Pocket Universes New Inflating Regions in the Universe

Linde and others later realized that the same quantum fluctuations that produced galaxies can give rise to new inflating regions in the universe. Even though inflation ended in our local cosmic neighborhood 13.8 billion years ago it can still continue in disconnected regions of space beyond the limits of our observable universe The consequence is an ever-expanding sea of inflating space-time dotted with pocket universes like our own where inflation has ceased.

As a result, the universe becomes a multiverse, an eternally growing fractal consisting of exponentially many exponentially large parts, Linde wrote. These parts are so large that for all practical purposes they look like separate universes.

Linde took the multiverse idea even further by proposing that each pocket universe could have differing properties, a conclusion that some string theorists were also reaching independently.

Its not that the laws of physics are different in each universe, but their realizations, Linde said. An analogy is the relationship between liquid water and ice. Theyre both H2O but realized differently.

Lindes multiverse is like a cosmic funhouse filled with reality-distorting mirrors. Some pocket universes are resplendent with life, while others were stillborn because they were cursed with too few (or too many) dimensions, or with physics incompatible with the formation of stars and galaxies. An infinite number are exact replicas of ours, but infinitely more are only near-replicas. Right now, there could be countless versions of you inhabiting worlds with histories divergent from ours in ways large and small. In an infinitely expanding multiverse, anything that can happen will happen.

The inflationary universe is not just the ultimate free lunch, its the only lunch where all possible dishes are served, Linde said.

While disturbing to some, this eternal aspect of inflation was just what a small group of string theorists were looking for to help explain a surprise discovery that was upending the physics world dark energy.

The Last Word -Brian Keating and Avi Loeb

When asked, will Lindes pocket universes be subject to the same laws of physics as our Universe, Brian Keating, Distinguished Professor of Physics at the Center for Astrophysics & Space Sciences at University of California, San Diego, told The Daily Galaxy: No, not necessarily. Its not mandatory that the properties of space-time be consistent from universe to universe. Nor is it impossible that the laws of logic and mathematics be consistent throughout the universe. This has led some physicists such as Paul Steinhart claiming that the multiverse concept is not a self-consistent or proper subject with the traditions of the scientific method.

Not so certain of the existence of Lindes free lunch, Harvard astrophysicist Avi Loeb told The Daily Galaxy: Advances in scientific knowledge are enabled by experimental tests of theoretical ideas. Physics is a dialogue with nature, not a monologue. I am eagerly waiting for a proposed experimental test of the multiverse idea.

Avi Shporer, Research Scientist, with the MIT Kavli Institute for Astrophysics and Space Research via Dan Hooper, Brian Keating, Avi Loeb and Stanford University

The Galaxy Report newsletter brings you twice-weekly news of space and science that has the capacity to provide clues to the mystery of our existence and add a much needed cosmic perspective in our current Anthropocene Epoch.

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Avi Shporer,Research Scientist, MIT Kavli Institute for Astrophysics and Space Research. AGoogle Scholar, Avi was formerly aNASA Sagan Fellowat the Jet Propulsion Laboratory (JPL). His motto, not surprisingly, is a quote from Carl Sagan: Somewhere, something incredible is waiting to be known.

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Quantum Birth of the Universe (Weekend Feature) - The Daily Galaxy --Great Discoveries Channel

Protons may have more "charm" than we thought, new research suggests.

A proton is one of the subatomic particles that make up the nucleus of an atom. As small as protons are, they are composed of even tinier elementary particles (opens in new tab) known as quarks, which come in a variety of "flavors," or types: up, down, strange, charm, bottom and top. Typically, a proton is thought to be made of two up quarks and one down quark.

But a new study finds it's more complicated than that. Protons can also contain a charm quark, an elementary particle that's 1.5 times the mass of the proton itself. Even weirder, when the proton does contain the charm quark, the heavy particle still only carries about half the proton's mass.

The finding all comes down to the probabilistic world of quantum physics (opens in new tab). Though the charm quark is heavy, the chance of it popping into existence in a proton is fairly small, so the high mass and small chance basically cancel each other out. Put another way, the full mass of the charm quark doesn't get taken up by the proton, even if the charm quark is there, Science News reported (opens in new tab).

Though protons are fundamental to the structure of atoms (opens in new tab) which make up all matter they're also very complicated. Physicists don't actually know protons' fundamental structure. Quantum physics holds that beyond the up and down quarks known to be present, other quarks might pop into protons now and then, Stefano Forte, a physicist at the University of Milan, told the podcast Nature Briefing (opens in new tab). Forte was a co-author of the new paper showing evidence for the charm quark in protons, published in the journal Nature (opens in new tab) Aug. 17.

There are six types of quarks. Three are heavier than protons and three are lighter than protons. The charm quark is the lightest of the heavy batch, so researchers wanted to start with that one to find out whether a proton could contain a quark heavier than itself. They did this by taking a new approach to 35 years of particle-smashing data.

Related: Why physicists are interested in the mysterious quirks of the heftiest quark (opens in new tab)

To learn about the structure of subatomic and elementary particles, researchers fling particles against each other at blistering speeds at particle accelerators such as the Large Hadron Collider, the world's largest atom smasher, located near Geneva. Scientists with the nonprofit NNPDF collaboration gathered this particle-smashing data going back to the 1980s, including examples of experiments in which photons, electrons, muons, neutri (opens in new tab)nos and even other protons were crashed into protons. By looking at the debris from these collisions, researchers can reconstruct the original state of the particles.

In the new study, the scientists handed over all of this collision data to a machine-learning algorithm designed to look for patterns without any preconceived notions of how the structures might look. The algorithm returned possible structures and the likelihood that they might actually exist.

The study found a "small but not negligible" chance of finding a charm quark, Forte told Nature Briefing. The level of evidence wasn't high enough for the researchers to declare the undeniable discovery of the charm quark in protons, but the results are the "first solid evidence" that it can be there, Forte said.

The structure of the proton is important, Forte said, because to discover new elementary particles, physicists will have to uncover minuscule differences in what theories suggest and what's actually observed. This requires extremely precise measurements of subatomic structures.

For now, physicists still need more data on the elusive "charm" within a proton. Future experiments, such as the planned Electron-Ion Collider at Brookhaven National Laboratory in Upton, New York, may help, Tim Hobbs, a theoretical physicist at Fermilab in Batavia, Illinois, told Science News.

Originally published on Live Science.

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Weird quantum experiment shows protons have more 'charm' than we thought - Space.com

Some of the worlds brightest minds are gathering at a hotel conference centre in Vancouver this week to try to solve a question that has baffled physicists for decades.

The two pillars of modern physics the theories of quantum mechanics and general relativity have been used respectively to describe how matter behaves, as well as space, time and gravity.

The problem is that the theories dont appear to be compatible, said Peter Galison, a professor in history of science and physics at Harvard University.

These theories cant just harmoniously live in splendid isolation, one from the other. We know our account of the world is inadequate until we figure out how to make them play nicely together, he said in an interview after giving a talk on how black holes fit into the equation.

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Galison is among several leading thinkers who arrived at the Quantum Gravity Conference for the launch a new global research collaborative known as the Quantum Gravity Institute in Vancouver.

While speakers at the conference are primarily scientists, including Nobel laureates Jim Peebles, Sir Roger Penrose and Kip Thorne, those behind the institute come from less likely fields.

The Quantum Gravity Society represents a group of business, technology and community leaders. Founding members include Frank Giustra of Fiore Group, Terry Hui of Concord Pacific, Paul Lee and Moe Kermani of Vanedge Capital and Markus Frind of Frind Estate Winery. They are joined by physicists Penrose, Abhay Ashtekar, Philip Stamp, Bill Unruh and Birgitta Whaley.

During a panel discussion, Lee said hes been asked several times why Vancouver would host such an event or institute.

Why Vancouver? Because we can, Lee said.

Hui, who studied physics as part of his undergraduate degree, said organizing the conference and launching the institute felt like fulfilling a childhood dream.

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I left the field to pursue other things, you know, he said in an interview.

How do I put this? he said, before likening it to being a guy who never made the high school hockey team getting to hang out in the Canucks locker room.

Hui said he wanted to help and saw his role as philanthropic, adding he believed it would benefit Vancouver economically.

As a non-local and the founder of the Black Hole Initiative at Harvard, Galison said hes happy to see more interdisciplinary support for exploring some of the biggest questions in science. He called the conference an interesting event for bringing together people in technology and venture capitalism with scientists from varied fields. The launch of the institute is also meaningful, he said.

Its also a kickoff event for something much bigger and longer-lasting.

As for the central question of the conference, Galison said its an opportunity to explore where the theories overlap and where they dont from different angles.

One place they intersect is clearly at the beginning of the universe, early cosmology, because when energy is incredibly compressed, when you have enormous energy densities, youre at the limit where the bending of space and time creates so much energy that quantum effects come into play, he said.

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The theory of quantum mechanics, introduced in the 1920s, entered a world already shaken by Albert Einsteins theory of relativity, which inspired responses not just from scientists but from poets and philosophers, he said.

That these things are not compatible is really unnerving, Galison said.

Cracking the code for why isnt something that will happen in a moment, a week or a year, he said.

Theres a tremendous amount of work, he said. Its more like building a cathedral than throwing up a bicycle shed.

2022 The Canadian Press

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Physicists and business figures gather in Vancouver to crack theory of everything - Global News

We know that the universe is expanding, and our understanding of nature based on general relativity and the Standard Model of elementary particles is consistent with this observation. However, these theories of particles and their interactions break down when we try to apply them to the physical phenomena that occurred in the first moments following the Big Bang preventing us from reaching a complete understanding of the evolution of the universe.

Our theories fail because the temperature and density of matter just after the Big Bang were so high that a concept called quantum gravity is required to describe the physical processes that took place. The problem is that this theory requires a unification of general relativity and quantum mechanics. Though this has not yet been fully understood, there are some viable candidates for a theory of quantum gravity, such as string theory.

To address the problem of unknown quantum gravitational effects in the early universe, a team of theoretical physicists from Japan applied a string theory-inspired technique known as holographic duality. This allowed them to perform calculations using familiar methods of elementary particle physics rather than an impossibly complex computation usually required in quantum gravity applications.

The most difficult problem one encounters on the way to finding a correct theory of quantum gravity is a lack of experimental data. Fundamental interactions are usually studied with elementary particle accelerators, which smash together beams of particles moving at velocities close to the speed of light. From the velocities of the particles born in these collisions and the angles at which they leave, scientists can extract valuable information about their fundamental interactions.

The key issue here is that the gravitational effects in most elementary particle interactions are negligible (though not under the extreme conditions in the early universe!), and they cannot be measured using modern accelerators. For example, the gravitational attraction between two electrons is more than 42 orders of magnitude weaker than the electromagnetic repulsion between them. Because of this, studies of quantum gravity have so far been only theoretical.

For decades, the most promising approach to quantum gravity has been string theory, the main postulate of which is that elementary particles are not point-like, but are tiny, oscillating strings. Unique vibrational modes of these strings gives rise to a different elementary particle, such as electrons, quarks, and yet-to-be observed gravitons, which should mediate gravitational interactions similar to how photons mediate electromagnetic interactions.

Unfortunately, our current understanding of string theory is incomplete and doesnt allow us to study many quantum gravitational effects quantitatively.

Although string theory has not yet reached its full potential, research in this area has led to the development of many theoretical tools that can be used outside of it. The most radical and powerful, although not fully proven, is known as holographic duality or correspondence.

The holographic hypothesis claims that events inside a region of space that involve quantum gravity and are described by string theory can also be described by a gravity-free quantum theory defined on the surface of that region. The latter theory is sufficiently easier to deal with, and we have learned much about theories of this type by studying electromagnetic, weak, and strong interactions.

The existence of this duality means that for every measurable quantity in quantum gravitational theory there must be an analogue in the gravity-free alternative. The validity of holographic duality has been verified by hundreds of research papers through direct calculations of various quantities on both sides of the duality.

Since 1997, when the first version of holographic correspondence was proposed by Juan Maldacena, many more pairs of theories connected by this equivalence have been discovered and analyzed, but the rule that a higher-dimensional space includes gravity and a lower-dimensional one does not always remains satisfied.

Some of these theories of quantum gravity are known to be related to string theory, whereas the connection between the rest with strings has not yet been uncovered but is usually believed to exist.

An unfortunate feature of the holographic approach in studying quantum gravity in the real world is that in most known examples of the duality, the higher-dimensional theory mathematically describes quantum gravity in what is called anti-de Sitter space, which doesnt look like our expanding universe, and whose geometry corresponds to what mathematicians call de Sitter space.

The remarkable achievement of the new study is that the authors were able to find a non-gravitational theory equivalent to quantum gravity in a universe that is quite similar to our own. The most important difference is that it has only three dimensions two spatial directions and one time unlike our own universe, which is four-dimensional (three space dimensions and one time dimension).

Gravity in three dimensions is much simpler than in four, said Tadashi Takayanagi, a professor at the Yukawa Institute for Theoretical Physics and one of the authors of the study. However, we believe the basic mechanism of how the holography works in de Sitter space should not depend on the dimension.

The new theory is proposed as an equivalent to quantum gravity in a lower-dimensional expanding universe defined in one spatial and one temporal dimension, known as the Wess-Zumino-Witten model.

Although the three-dimensional universe they deal with is not exactly like ours, the authors think that their work is an important step towards understanding quantum gravity in the real world.

Since we do not know at all the basic mechanisms of how the holography in de Sitter spaces works, it is useful to start with constructing the most simple example, as we did in this work, said Takayanagi. At the same time, this helps us to verify whether a holographic duality exists for de Sitter spaces or not. Moreover, in our simple mode, we can take into account quantum corrections [to general relativity].

As is usual in this branch of theoretical physics, the scientists havent proven the duality because to do so, they would have to compute all possible physical quantities on both sides of the correspondence and compare the results. Instead, they computed some, and found an exact match from which they concluded that their guess was correct.

Most of the authors calculations ignored quantum effects on the gravitational side of duality and taking them into account will be the course of future work. If the scientists are successful in this, they plan to generalize their results and apply them to our four-dimensional universe.

If we can understand this question from our three-dimensional example, we hopewe can generalize the results to higher dimensions and finally challenge theproblem of explaining the emergence of our four-dimensional universe, concluded Takayanagi.

Reference: Yasuaki Hikida, et al., CFT duals of three-dimensional de Sitter gravity, Journal of High Energy Physics, (2022). DOI: 10.1007/JHEP05(2022)129

Image Credit: Johnson Martin Pixabay

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String theory used to describe the expanding universe - Advanced Science News

Of all the pricing games on the iconic television showThe Price Is Right, perhaps the most exciting of all isPlinko. Contestants play an initial pricing game to obtain up to 5 round, flat disksknown as Plinko chipswhich they then press flat against a pegboard wherever they choose, releasing it whenever they like. One-at-a-time, the Plinko chips cascade down the board, bouncing off of the pegs and moving horizontally as well as vertically, until they emerge at the bottom of the board, landing in one of the prize (or no prize) slots.

Quite notably, contestants who drop a chip that happens to land in the maximum prize slot, always found in the direct center of the board, often try to repeat the exact same drop with whatever remaining disks they possess. Despite their best efforts, however, and the fact that the initial positioning of the disks might be virtually identical, the ultimate paths the disks wind up traversing are almost never identical. Surprisingly, this game is a perfect illustration of chaos theory and helps explain the second law of thermodynamics in understandable terms. Heres the science behind it.

Trajectories of a particle in a box (also called an infinite square well) in classical mechanics (A) and quantum mechanics (B-F). In (A), the particle moves at constant velocity, bouncing back and forth. In (B-F), wavefunction solutions to the Time-Dependent Schrodinger Equation are shown for the same geometry and potential. The horizontal axis is position, the vertical axis is the real part (blue) or imaginary part (red) of the wavefunction. These stationary (B, C, D) and non-stationary (E, F) states only yield probabilities for the particle, rather than definitive answers for where it will be at a particular time.

At a fundamental level, the Universe is quantum mechanical in nature, full of an inherent indeterminism and uncertainty. If you take a particle like an electron, you might think to ask questions like:

Theyre all reasonable questions, and wed expect that theyd all have definitive answers.

But what actually transpires is so bizarre that its enormously unsettling, even to physicists whove spent their lifetimes studying it. If you make a measurement to precisely answer Where is this electron? you become more uncertain about its momentum: how fast and in what direction it moves. If you measure the momentum instead, you become more uncertain about its position. And because you need to know both momentum and position to predict where it will arrive with any certainty in the future, you can only predict a probability distribution for its future position. Youll need a measurement at that future time to determine where it actually is.

In Newtonian (or Einsteinian) mechanics, a system will evolve over time according to completely deterministic equations, which should mean that if you can know the initial conditions (like positions and momenta) for everything in your system, you should be able to evolve it, with no errors, arbitrarily forward in time. In practice, due to the inability to know the initial conditions to truly arbitrary precisions, this is not true.

Perhaps for Plinko, however, this quantum mechanical weirdness shouldnt matter. Quantum physics might have a fundamental indeterminism and uncertainty inherent to it, but for large-scale, macroscopic systems, Newtonian physics ought to be perfectly sufficient. Unlike the quantum mechanical equations that govern reality at a fundamental level, Newtonian physics is completely deterministic.

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According to Newtons laws of motionwhich can all be derived fromF= ma(force equals mass times acceleration)if you know the initial conditions, like position and momentum, you should be able to know exactly where your object is and what motion it will possess at any point in the future. The equationF= matells you what happens a moment later, and once that moment has elapsed, that same equation tells you what happens after the next moment has passed.

Any object for which quantum effects can be neglected obeys these rules, and Newtonian physics tells us how that object will continuously evolve over time.

However, even with perfectly deterministic equations,theres a limit to how well we can predict a Newtonian system. If this surprises you, know that youre not alone; most of the leading physicists who worked on Newtonian systems thought that there would be no such limit at all. In 1814, mathematician Pierre Laplace wrote a treatise entitled, A philosophical essay on probabilities, where he predicted that once we gained enough information to determine the state of the Universe at any moment in time, we could successfully use the laws of physics to predict the entire future of everything absolutely: with no uncertainty at all. In Laplaces own words:

An intellect which at a certain moment would know all forces that set nature in motion, and all positions of all items of which nature is composed, if this intellect were also vast enough to submit these data to analysis, it would embrace in a single formula the movements of the greatest bodies of the universe and those of the tiniest atom; for such an intellect nothing would be uncertain and the future just like the past would be present before its eyes.

A chaotic system is one where extraordinarily slight changes in initial conditions (blue and yellow) lead to similar behavior for a while, but that behavior then diverges after a relatively short amount of time.

And yet, the need to invoke probabilities in making predictions about the future doesnt necessarily stem from either ignorance (imperfect knowledge about the Universe) or from quantum phenomena (like Heisenbergs uncertainty principle), but rather arises as a cause of the classical phenomenon: chaos. No matter how well you know the initial conditions of your system, deterministic equationslike Newtons laws of motiondont always lead to a deterministic Universe.

This was first discovered back in the early 1960s, when Edward Lorenz, a meteorology professor at MIT, attempted to use a mainframe computer to help arrive at an accurate weather forecast. By using what he believed was a solid weather model, a complete set of measurable data (temperature, pressure, wind conditions, etc.), and an arbitrarily powerful computer, he attempted to predict weather conditions far into the future. He constructed a set of equations, programmed them into his computer, and waited for the results.

Then he re-entered the data, and ran the program for longer.

Two systems starting from an identical configuration, but with imperceptibly small differences in initial conditions (smaller than a single atom), will keep to the same behavior for a while, but over time, chaos will cause them to diverge. After enough time has gone by, their behavior will appear completely unrelated to one another.

Surprisingly, the second time he ran the program, the results diverged at one point by a very slight amount, and then diverged thereafter very quickly. The two systems, beyond that point, behaved as though they were entirely unrelated to one another, with their conditions evolving chaotically with respect to one another.

Eventually, Lorenz found the culprit: when Lorenz re-entered the data the second time,he used the computers printout from the first runfor the input parameters, which was rounded off after a finite number of decimal places. That tiny difference in initial conditions might have only corresponded to the width of an atom or less, but that was enough to dramatically alter the outcome, particularly if you time-evolved your system far enough into the future.

Small, imperceptible differences in the initial conditions led to dramatically different outcomes, a phenomenon colloquially known as the Butterfly Effect. Even in completely deterministic systems, chaos arises.

A scaled-down, casino-esque version of the game of Plinko, where instead of chips falling down a Plinko board, coins fall, with varying rewards available depending on where the coins land.

All of this brings us back to the Plinko board. Although there are many version of the game available, including at amusement parks and casinos, theyre all based on the idea of a Galton Board, where objects bounce one way or the other down an obstacle-filled ramp. The actual board used on The Price Is Right has somewhere around 1314 different vertical levels of pegs for each Plinko chip to potentially bounce off of. If youre aiming for the central spot, there are a lot of strategies you can employ, including:

Every time your chip hits a peg on the way down, it has the potential to knock you one-or-more spaces to either side, but every interaction is purely classical: governed by Newtons deterministic laws. If you could stumble upon a path that caused your chip to land exactly where you desired, then in theory, if you could recreate the initial conditions precisely enoughdown to the micron, the nanometer, or even the atomperhaps, even with 13 or 14 bounces, you might wind up with an identical-enough outcome, winning the big prize as a result.

But if you were to expand your Plinko board, the effects of chaos would become unavoidable. If the board were longer and had dozens, hundreds, thousands, or even millions of rows, youd quickly run into a situation where even two drops that were identical to within the Planck lengththefundamental quantum limit at which distances make sensein our Universeyoud start to see the behavior of two dropped Plinko chips diverging after a certain point.

In addition, widening the Plinko board allows for a greater number of possible outcomes, causing the distribution of final states to be greatly spread out. Put simply, the longer and wider the Plinko board is, the greater the odds of not only unequal outcomes, but of having unequal outcomes that display an enormous-magnitude difference between two dropped Plinko chips.

Even with down-to-the-atom initial precisions, three dropped Plinko chips with the same initial conditions (red, green, blue) will lead to vastly different outcomes by the end, so long as the variations are large enough, the number of steps to your Plinko board is great enough, and the number of possible outcomes is sufficiently large. With those conditions, chaotic outcomes are inevitable.

This doesnt just apply to Plinko, of course, but to any system with a large number of interactions: either discrete (like collisions) or continuous (such as from multiple gravitational forces acting simultaneously). If you take a system of air molecules where one side of a box is hot and the other side is cold, and you remove a divider between them, collisions between those molecules will spontaneously occur, causing the particles to exchange energy and momenta. Even in a small box, there would be more than 1020 particles; in short order, the entire box will have the same temperature, and will never separate into a hot side and a cold side again.

Even in space, justthree point masses is enough to fundamentally introduce chaos. Three massive black holes, bound within distances the scale of the planets in our Solar System, will evolve chaotically no matter how precisely their initial conditions are replicated. The fact that theres a cutoff in how small distances can get and still make senseagain, the Planck lengthensures that arbitrary accuracies on long-enough timescales can never be ensured.

By considering the evolution and details of a system with as few as three particles, scientists have been able to show that a fundamental time irreversibility arises in these systems under realistic physical conditions that the Universe is very likely to obey. If you cannot calculate distances meaningfully to arbitrary precisions, you cannot avoid chaos.

The key takeaway of chaos is this: even when your equations are perfectly deterministic, you cannot know the initial conditions to arbitrary sensitivities. Even placing a Plinko chip on the board and releasing it with down-to-the-atom precision wont be enough, with a large enough Plinko board, to guarantee that multiple chips would ever take identical paths. In fact, with a sufficiently large board, you can all but guarantee that no matter how many Plinko chips you dropped, youd never arrive at two truly identical paths. Eventually, theyd all diverge.

Minuscule variationsthe presence of air molecules moving from the hosts announcing, temperature variations arising from the contestants breath, vibrations from the studio audience propagating into the pegs, etc.introduce enough uncertainty so that, far enough down the line, these systems are effectively impossible to predict. Along with quantum randomness, this effective classical randomness prevents us from knowing the outcome of a complex system, no matter how much initial information we possess. Asphysicist Paul Halpern so eloquently put it, God plays dice in more ways thanone.

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To understand chaos theory, play a game of Plinko - Big Think

For those who pay attention, it will be noticed that there is a huge inconsistency in the world. Many people are deluded about a lot of things and are acting in opposition to what is logically consistent.

For example, there seems to be a disproportionate number of people who are meeting their demise lately, but no matter who it is, people are confident, based on their condolence comments, that the person is going to heaven. This includes people who would be known as trouble-makers while alive.

People do not stop to think that heaven will not accommodate car-jackers, backbiters, murderers and so many others who have created mayhem on Earth, if, indeed, heaven is a reality.

Another example of illogical behavior is demonstrated by those individuals who are so deluded that they actually believe former president Donald J. Trump was the best president ever, and that those who stormed the capital on January 6, 2021, were mere tourists.

Basically, the problem is that a lot of people are not thinking logically, and have unrealistic expectations that are counter to their actions. One of these is the notion of freedom among people who are not doing anything to ensure that it is achieved.

When considering the foregoing, it becomes evident that there is a great divide; a split between the idea of mind over matter. How we think and what we do lays the foundation for all of our outcomes, and when these are not in sync, chaos results.

Black people, in particular, need to understand this great divide. For example, some resent the use of the word ni**er by white people, but use it constantly among themselves and in public media, making it available for all to hear.

Likewise, those who commit heinous crimes in the Black community are often not blamed for their actions; condolences are publicly sent to families, and teddy bears, flowers and more are deposited at the locations where people lost their lives to violence, but people in the community who know the identities of the perpetrators refuse to reveal that information.

All of this points to the idea that freedom will not be available to us as long as there is a schism between mind and matter. The idea of freedom requires that mind and matter are in sync in order for manifestation to occur.

And just what is freedom? According to the Oxford Languages dictionary, freedom is the power or right to act, speak, or think as one wants without hindrance or restraint. A second definition is an absence of subjection to foreign domination or despotic government.

The problem with acquiring either or both of these forms of freedom is dependent upon how we think and what we do as a result. If people continue to think that they can act in exact opposition to what is mentally required for success, so-called freedom will never be achieved.

The newly deployed James Webb Space Telescope is opening up new vistas and is enabling humanity to see the universe with a clarity that has not been possible before. Mankind is becoming aware of the vastness of existence. This will hopefully result in the realization among the human family that our collective destiny will ultimately depend upon what we do and how we think in the here and now!

New discoveries in quantum physics are revealing a startling truth: that it is really quite possible that our lives are scripted by how effectively we are able to repair our mind/matter rift. In other words, when we focus on what we want to achieve and then act in accordance with our mental assertion, we can achieve our goals.

This idea can be applied to the notion of freedom.

All around us, there are examples of the efficacy of this strategy. For example, although economic success is not the only gauge to measure success, the existence of 15 living Black billionaires does demonstrate that there are Black people who have discovered the secret to making their dreams come true. They have been able to ensure that their actions are in sync with their ideas!

The formula for success, therefore, is for people to identify a goal and make sure their actions are in line with their ideas, with their thoughts, with their minds wishes regarding that goal.

This is how freedom must be attained, and its unrealistic to think that it will be acquired without considering both elements of the process, i.e., the mind and physical activities toward the accomplishment of the goal. A Luta Continua.

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FREEDOM AND THE MIND/MATTER CONNECTION - The Chicago Cusader

You might have noticed, if youve set foot in a cinema this year, that Hollywood has fallen in love with the multiverse. From Marvel to DC to Disney, alternate universes, realities and timelines are being written into scripts to wow audiences and make life a bit easier when A-list celebrities tire of yanking on the latex.

Its not just the big studios that are at it. The sublimely joyful indie film Everything Everywhere All At Once asks and answers, why, if everything is happening everywhere and all at once, should any of it matter?

Likewise, Rick And Morty, Dark and Man In The High Castle use the idea of alternate universes as a kind of funhouse mirror to ponder (sometimes) serious questions about our own Universe. And its fair to point out that the idea is nothing new. Who could forget Spocks evil doppelgnger with his suitably sinister goatee? Clearly, the idea of the multiverse has permeated the fabric of our culture. But what do the scientists think about multiverses? Is there the science to back them up?

Many physicists believe that multiverses could exist, ranging from universes lurking behind the event horizons of black holes, to growing universes expanding like bubbles in soap foam.

A multiverse is something which is really not that strange if you think of it historically, from the point of view of science, says Prof Ulf Danielsson, a theoretical physicist at Uppsala University, Sweden. Our horizons have continuously been expanding. At some time, we thought that Earth was the only planet and that this was the whole world. We now know theres a Universe full of other planets. Its also quite natural to speculate that there is another step and that our Universe is not the only one.

So what are some of the leading multiverse theories, and which of them could harbour an evil, possibly moustachioed, you.

Read more about the multiverse:

This is a theory that has grown out of cosmology, particularly from the discovery that our own Universe is expanding. This concept of a multiverse asks if the initial rapid inflation that our Universe underwent some 13.8 billion years ago, could be happening in distant regions of space-time disconnected from our Universe.

The basic idea is that our Universe is one particular patch of space-time that is evolving as a well-defined entity, explains astrophysicist Prof Fred Adams, from the University of Michigan. This region is homogeneous, isotropic [the same in all directions] and expanding in a well-defined manner. If you trace the evolution backward in time, then you find an age for the Universe of about 13.8 billion years from this initial expansion.

Adams, who wrote the book Our Living Multiverse and authored a Physics Report paper on the topic, also believes that other regions of the multiverse could be experiencing their own Big Bangs, and therefore their own expansions. This means that they are not able to affect our Universe. They are thus other universes and the collection of all such universes is the multiverse, Adams says.

This multiverse idea caught on in fiction because it is an excellent storytelling device. It became popular in cosmology because it could address lingering mysteries, while still fitting with existing physics.

One reason that the concept of the multiverse became popular is that it can naturally arise from the theory of inflation, explains Heling Deng, a postdoctoral researcher in cosmology, particle physics and astrophysics at Arizona University.

It was shown by [physicists] Andrei Linde and Alex Vilenkin, in separate works, that if inflation did occur, it could create infinite disconnected regions.

Although inflation ended 13.8 billion years ago in the Universe we are living in, Deng says that quantum effects can always bring inflation back in another region of space-time. This results in bouts of inflation never ending referred to as eternal inflation and the possibility of an infinite number of different universes.

Stages in the history of the Universe after the Big Bang Science Photo Library

Russian-American theoretical physicist Andrei Linde puts forward one suggestion for the arrangement of this multiverse. He sees the universes as bubbles expanding on something resembling a cosmic canvas, squeezing away from each other in bouts of eternal and chaotic inflation.

How these universes within a multiverse would differ is also currently the topic of speculation, but Adams suggests theres no reason to believe that the laws of physics would be the same in these separate regions.

One reason that these other universes are of interest is that they could have other versions of the laws of physics, he says. That variation could apply across a range of physical parameters, including gravity and the rate at which that universe expands.

That means some of these universes could have laws of physics that arent fit for the formation of large-scale structures like galaxies or stars. They may not even have the same fundamental particles.

Consequently, these universes arent variations of our Universe and thus could not host any life at all, never mind some version of you or I.

String theory is a suggestion put forward by physicists to connect quantum mechanics and General Relativity, which are the best descriptions we have of the infinitesimally small and incomprehensibly large. The underlying idea of string theory is that fundamental particles like quarks and electrons are actually a single point in one-dimensional strings, vibrating at different frequencies.

This string-landscape provides a popular setting for the multiverse, thanks to one of the key elements upon which string theory depends. In order to be mathematically sound, string theory needs extra dimensions to exist.

These arent parallel dimensions like we see in science fiction. Instead, string theorists believe these extra dimensions are curled up within the three traditional dimensions of space. They remain invisible to us, as we evolved only to see in three dimensions. These extra dimensions could offer a way in to the string theory multiverse.

String theory attempts to explain all the fundamental particles in nature by modelling them as tiny strings Science Photo Library

You need to have these extra dimensions, and the number of dimensions needed in total is 10 or 11, Danielsson says. It could also be that you would need to go into some extra dimension in order to get to these other universes.

Even if this was the case and a connection via these dimensions of space to other universes existed, they may still remain permanently out of reach and view, thanks to the fact that the inflation of the Universe means that there is a cosmic horizon beyond which we cant see. If there is no connectivity between universes in a multiverse, it makes the cosmological concept of a multiverse almost impossible to test experimentally.

The evidence to date is theoretical, not experimental. And, unfortunately, we just cannot do any direct experiments to verify or falsify what goes on in other universes, Adams explains.

Our inability to test these ideas is a double-edged sword. While the lack of ways to test a multiverse means we cant prove its existence, it also means we cant disprove it either.

At the end of a massive stars life, when it has run out of fuel for nuclear fusion, itll collapse into a black hole a region of space-time bounded by a surface called an event horizon from which nothing, not even light, can escape.

Einsteins General Theory of Relativity tells us that a large mass can curve space-time. The theory also says that the heart of a black hole has a singularity where the mass is so great that the space-time curvature becomes infinite and, consequently, the laws of physics break down. This is a concept that troubles physicists, but one hypothesis could do away with the singularity and replace it with an entire universe and in turn, a multiverse.

Singularities are unphysical because they cannot be measured. That means their existence indicates that a theory is incomplete, says theoretical physicist Dr Nikodem Poplawski, from the University of New Haven, Connecticut. In my hypothesis, every black hole produces a new, baby universe inside on the other side of the event horizon and becomes an Einstein-Rosen bridge, also known as a wormhole, that connects this infant universe to the parent universe in which the black hole exists.

Could a black hole spawn a new baby universe? This illustration is of a wormhole, a hypothetical shortcut connecting two separate points in space-time Science Photo Library

In this theory, when viewed from the new universe, the parent universe appears as the other side of a white hole, a region of space that cannot be entered from the outside and which can be thought of as the reverse of a black hole.

An analogy of the matter going to a black hole and ending up in a new universe could be blowing a soap bubble through a circular wand, Poplawski says. The wand is the event horizon albeit in one dimension less the soap liquid is the matter crossing the event horizon, and the surface of the bubble is the new universe.

In the hypothesis suggested by Poplawski, a universe may produce billions of black holes and each of them could produce a baby universe. In January of this year, researchers at the International School of Advanced Studies (SISSA) in Italy estimated that there could be as many as 40 trillion thats a four followed by 13 zeros black holes in our Universe alone. Thats a lot of baby universes!

These infant universes would be hidden from the occupants of their parent universe by the light-trapping surface of the event horizon, and once that event horizon is crossed theres no going back. That, and the fact nothing can enter a white hole (which is still purely theoretical but allowed by General Relativity), means no interaction between parent and infant.

According to Einstein's General Theory of Relativity, large objects cause space-time to curve Science Photo Library

However, if two black holes existed in the same universe, and each of these black holes created a new universe, then there is a possibility that these two sibling universes could merge, just as two black holes merge to create one black hole, says Poplawski.

He adds that this would manifest in a baby universe as a large-scale asymmetry in space. This means that if we ever discover some preferred direction in our Universe a direction with increasing matter and energy, for example it could be attributed to our Universe interacting with a sibling.

As for the possibility of an alternate version of you existing beyond the event horizon of a black hole, Poplawski concludes that chances are not good. There would be no alternate you. At any time, an object can only exist in one universe, he says.

But one pop culture mainstay reflects his concept: I think the closest thing could be the TARDIS in Doctor Who. You enter the police box and you realise that you are in something bigger than the box.

In quantum physics, which deals with the physical laws of the subatomic, the term multiverse doesnt exist. Alternate universes are instead referred to as many worlds and are part of a radically different concept, as these arent geographic in nature like the multiverses explored previously.

The many-worlds hypothesis was first suggested by the US physicist Hugh Everett III to explain how a quantum system can exist in seemingly contradictory states at the same time called a superposition and how these paradoxical states seem to vanish.

The effect of many worlds on the existence of a superposition of states can be imagined by considering Erwin Schrdingers infamous thought experiment, Schrdingers cat.

Schrdinger's cat can help explain superposition, but also quantum multiverses Science Photo Library

In the thought experiment, a hapless moggy is placed in a sealed box with a device containing a vial of lethal poison, released only if an atomic nucleus in the box decays. Treating the box, the cat and the device as a single quantum system, each state in this case, dead or alive is described by a wave. As waves can overlap to form a single wave function, the cat can exist in a superposition of states. This means that in quantum mechanics the cat is both simultaneously dead or alive.

This seemingly contradictory state persists only until the box is opened analogous to making a measurement on the system and the wave function collapses meaning the superposition is gone and the state is resolved. The cat is either dead or alive. Yet why measurement causes this collapse of superposition, also known as decoherence, is still a mystery.

The many-worlds hypothesis does away with decoherence altogether. Instead, it suggests that rather than the opening of the box collapsing the wave function, measurement causes it to grow exponentially and swallow the experimenter and eventually the entire Universe.

In the many-worlds formulation of quantum mechanics, each state of a system is a physically distinct world, says Prof Jeffrey Barrett, a philosopher of science at the University of California Irvine.

This means each flick of a light switch would create a near-infinity of worlds. One for each possible path of each photon as the light fills your living room, not just a world in which you didnt flick the switch at all.

That means that in terms of Schrdingers cat thought experiment, the experimenter isnt opening the box to discover if the cat is dead or alive. Rather, they are opening the box to discover if they are in a world in which the cat is dead, or one in which it lives.

At first, the worlds that comprise this quantum multiverse are similar, with infinitesimally small differences. But these changes grow from universe to universe, meaning those that diverged earlier could be strikingly different from each other.

The objects, events and physical records of observers are different in different worlds. There is a world where the Eiffel Tower is in Los Angeles, Barrett says. All of the worlds universes are part of a single global universe. It looks just like this universe from the perceptive of our branch world.

Barrett addresses the question of how likely it is that one of these many worlds would contain an alternate you. He reveals that it isnt just possible, its demanded.

It certainly would contain many alternate copies of me, he says. That is fundamental to how the theory addresses the quantum measurement problem.

All of this makes the quantum version of the multiverse the one that most closely resembles pop culture, at least in principle. This is because it doesnt just probably contain infinite versions of you, it definitely does.

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Evil doppelgngers, alternate timelines and infinite possibilities: the physics of the multiverse explained - BBC Science Focus Magazine

(09:20) And then we have a bunch of matter fields, they come in three groups of four. The most familiar ones are an electron field, two quark fields associated to the up and the down quark. The proton contains oh man, I hope we get this right two up and down and the neutron contains two down and an up, I think, Ive got that the right way around.

Strogatz (09:41): You could fool me either way. I can never remember.

Tong (09:43): Yeah, but the listeners are gonna know. And then a neutrino field. So theres this collection of four particles interacting with three forces. And then for a reason that we really do not understand, the universe decided to repeat those matter fields twice over. So there is a second collection of four particles called the muon, the strange the charm and another neutrino. We sort of ran out of good names for neutrinos, so we just call it the muon neutrino. And then you get another collection of four: the tau, the top quark, the bottom quark and, again, a tau neutrino. So nature has this way of repeating itself. And no one really knows why. I think that remains one of the big mysteries. But those collections of 12 particles interacting with three forces comprises the Standard Model.

(09:43) Oh, and I missed one. The one I missed is important. Its the Higgs boson. The Higgs boson sort of ties everything together.

Strogatz (10:37): All right, thats tantalizing. Maybe we should say a little what the Higgs boson does, what role does it play in the Standard Model.

Tong (10:43): It does something rather special. It gives a mass to all the other particles. I would love to have a good analogy to explain how it gives mass. I can give a bad analogy, but it really is a bad analogy. The bad analogy is that this Higgs field is spread throughout all of space, thats a true statement. And the bad analogy is it acts a little like treacle or molasses. The particles sort of have to push their way through this, this Higgs field to make any progress. And that sort of slows them down. They would naturally travel at the speed of light, and they get slowed down by the presence of this Higgs field. And that is responsible for the phenomenon that we call mass.

(11:22) A large part of what I just said is basically a lie. I mean, it sort of suggests that theres some friction force at play. And thats not true. But its one of those things where the equations are actually surprisingly easy. But its rather hard to come up with a compelling analogy that captures those equations.

Strogatz (11:36): Its an amazing statement that you made, that without the Higgs field or some, I guess, some analogous mechanism, everything would be moving at the speed of light. Did I hear you right?

Tong (11:47): Yes, except, as always, these things, its yes, with a caveat. The but is if the Higgs field turned off, the electron would move at the speed of light. So you know, atoms would not be particularly stable. The neutrino, which is almost massless anyway, would travel at the speed of light. But the proton or neutron, it turns out, would have basically the same masses that they have now. You know, the quarks inside them would be massless. But the mass of the quarks inside the proton or neutron, are totally trivial compared to the proton or neutron 0.1%, something like that. So the proton or neutron actually get their mass from a part of quantum field theory that we understand least, but wild fluctuations of quantum fields, is whats going on inside the proton or neutron and giving them their mass. So the elementary particles would become massless quarks, electrons but the stuff were made of neutrons and protons would not. They get their mass from this other mechanism.

Strogatz (12:42): Youre just full of interesting things. Lets see if I can say what Im thinking in response to that. And you can correct me if Ive got it completely wrong. So Ive got these strongly interacting quarks inside, say, a proton. And I keep in my mind guessing theres some E = mc2 connection going on here, that the powerful interactions are associated with some large amount of energy. And thats somehow translating into mass. Is it that, or is that theres virtual particles being created and then disappearing? And all of that is creating energy and therefore mass?

Tong (13:16): Its both of the things you just said. So we tell this lie when were in high school physics is all about telling lies when youre young and realizing that things are a bit more complicated as you grow older. The lie we tell, and I already said it earlier, is that there are three quarks inside each proton and each neutron. And its not true. The correct statement is that there are many hundreds of quarks and antiquarks and gluons inside a proton. And statement that there are really three quarks, the proper way of saying it is that at any given time, there are three more quarks than there are antiquarks. So theres sort of an additional three. But its an extraordinarily complicated object, the proton. It, its nothing nice and clean. It contains these hundreds, possibly even thousands of different particles interacting in some very complicated way. You could think about these quark-antiquark pairs as being, as you say, virtual particles, things that just pop out of the vacuum and pop back in again inside the proton. Or another way of thinking about it is just the fields themselves are excited in some complicated fashion inside the proton or neutron thrashing around and thats whats giving them their mass.

Strogatz (14:20): Earlier, I hinted that this is a very successful theory and mentioned something about 12 decimal places. Can you tell us about that? Because that is one of the great triumphs, I would say not just of quantum field theory, or even physics, but all of science. I mean, humanitys attempt to understand the universe, this is probably the best thing weve ever done. And from a quantitative standpoint, we as a species.

Tong (14:42): I think thats exactly right. Its kind of extraordinary. I should say that theres a few things we can calculate extraordinarily well, when we know what were doing, we can really do something spectacular.

Strogatz (14:42): Its enough to get you sort of in a philosophical mood, this question of the unreasonable effectiveness of mathematics.

Tong (14:52): So, the particular object or the particular quantity, that is the poster boy for quantum field theory, because we can calculate it very well albeit taking many, many decades to do these calculations, theyre not easy. But also importantly, we can measure it experimentally very well. So its a number called g-2 , its not particularly important in the grand scheme of things, but the number is the following. If you take an electron, then it has a spin. The electron spins about some axis not dissimilar to the way the Earth spins about its axis. Its more quantum than that, but its not a bad analogy to have in mind.

(14:59) And if you take the electron, and you put it in a magnetic field, the direction of that spin precesses over time, and this number g-2 just tells you how fast it precesses, the -2 is slightly odd. But you would naively think that this number would be 1. And [Paul] Dirac won the Nobel Prize in part for showing that actually this number is 2 to first approximation. Then [Julian] Schwinger won the Nobel Prize, together with [Richard] Feynman and [Sin-Itiro] Tomonaga, for showing that, you know, its not 2, its 2-point-something-something-something. Then over time, weve made that something-something-something with another nine somethings afterwards. As you said, its something that we now know extremely well theoretically and extremely well experimentally. And its just astonishing to see these numbers, digit after digit, agreeing with each other. Its something rather special.

(15:21) This is one of the things that pushes you in that direction is that its so good. Its so good that this isnt a model for the world, this is somehow much closer to the actual world, this equation.

Strogatz (16:31): So having sung the praises of quantum field theory, and it does deserve to be praised, we should also recognize that its an extremely complicated, and in some ways, problematic theory or set of theories. And so in this part of our discussion, I wonder if you could help us understand what reservation should we have? Or where the frontier is. Like, the theory is said to be incomplete. What is incomplete about it? What are the big remaining mysteries about quantum field theory?

Tong (17:01): You know, it really depends on what you subscribe to. If youre a physicist and you want to compute this number g-2, then theres nothing incomplete about quantum field theory. When the experiment gets better, you know, we calculate or we do better. You can really do as well as you want to. Theres several axes to this. So let me maybe focus on one to begin with.

(17:22) The problem comes when we talk to our pure mathematician friends, because our pure mathematician friends are smart people, and we think that we have this mathematical theory. But they dont understand what were talking about. And its not their fault, its ours. That the mathematics were dealing with is not something thats on a rigorous footing. Its something where were playing sort of fast and loose with various mathematical ideas. And were pretty sure we know what were doing as this agreement with experiments shows. But its certainly not at the level of rigor that, well, certainly mathematicians would be comfortable with. And I think increasingly that we physicists are also growing uncomfortable with.

(17:22) I should say that this isnt a new thing. Its always the case whenever there are new ideas, new mathematical tools, that often the physicists take these ideas and just run with them because they can solve things. And the mathematicians are always they like the word rigor, maybe the word pedantry is better. But now, theyre kind of going slower than us. They dot the is and cross the Ts. And somehow, with quantum field theory, I feel that, you know, its been so long, theres been so little progress that maybe were thinking about it incorrectly. So thats one nervousness is that it cant be made mathematically rigorous. And its not through want of trying.

Strogatz (18:33): Well, lets try to understand the nub of the difficulty. Or maybe there are many of them. But you spoke earlier about Michael Faraday. And at each point in space, we have a vector, a quantity that we could think of as an arrow, its got a direction and a magnitude, or if we prefer, we could think of it as three numbers maybe like an x, y and z component of each vector. But in quantum field theory, the objects defined at each point are, I suppose, more complicated than vectors or numbers.

Tong (18:33): They are. So the mathematical way of saying this is that at every single point, there is an operator some, if you like, infinite dimensional matrix that sits at each point in space, and acts on some Hilbert space, that itself is very complicated and very hard to define. So the mathematics is complicated. And in large part, its because of this issue that the world is a continuum, we think that space and time, space in particular, is continuous. And so you have to define really something at each point. And next to one point, infinitesimally close to that point is another point with another operator. So theres an infinity that appears when you look on smaller and smaller distance scales, not an infinity going outwards, but an infinity going inwards.

(19:44) Which suggests a way to get around it. One way to get around it is just to pretend for these purposes, that space isnt continuous. In fact, it might well be that space isnt continuous. So you could imagine thinking about having a lattice, what mathematicians call a lattice. So rather than have a continuous space, you think about a point, and then some finite distance away from it, another point. And some finite distance away from that, another point. So you discretize space, in other words, and then you think about what we call the degrees of freedom, the stuff that moves as just living on these lattice points rather than living in some continuum. Thats something that mathematicians have a much better handle on.

(19:44) But theres a problem if we try to do that. And I think its one of the deepest problems in theoretical physics, actually. Its that some quantum field theories, we simply cannot discretize in that way. There is a mathematical theorem that forbids you from writing down a discrete version of certain quantum field theories.

Strogatz (20:41): Oh, my eyebrows are raised at that one.

Tong (20:43): The theorem is called the Nielsen-Ninomiya theorem. Among the class of quantum field theories that you cannot discretize is the one that describes our universe, the Standard Model.

Strogatz (20:52): No kidding! Wow.

Tong (20:54): You know, if you take this theorem at face value, its telling us were not living in the Matrix. The way you simulate anything on a computer is by first discretizing it and then simulating. And yet theres a fundamental obstacle seemingly to discretizing the laws of physics as we know it. So we cant simulate the laws of physics, but it means no one else can either. So if you really buy this theorem, then were not living in the Matrix.

Strogatz (21:18): Im really enjoying myself, David. This is so, so interesting. I never had a chance to study quantum field theory. I did get to take quantum mechanics from Jim Peebles at Princeton. And that was wonderful. And I did enjoy that very much, but never continued. So quantum field theory, Im just in the position of many of our listeners here, just looking in agog at all the wonders that youre describing,

Tong (21:41): I can tell you a little more about the exact aspect of the Standard Model that makes it hard or impossible to simulate on a computer. Theres a nice tagline, I can add like a Hollywood tagline. The tagline is, Things can happen in the mirror that cannot happen in our world. In the 1950s, Chien-Shiung Wu discovered what we call parity violation. This is the statement that when you look at something happening in front of you, or you look at its image in a mirror, you can tell the difference, you can tell whether it was happening in real world or happening in the mirror. Its this aspect of the laws of physics, that what happens reflected in a mirror is different from what happens in reality, that turns out to be problematic. Its that aspect thats difficult or impossible to simulate, according to this theory.

Strogatz (22:28): Its hard to see why I mean, because the lattice itself wouldnt have any problem coping with the parity. But anyway, Im sure its a subtle theorem.

Tong (22:36): I can try to tell you a little bit about why every particle in our world electrons, quarks. They split into two different particles. Theyre called left-handed and right-handed. And its basically to do with how their spin is changing as they move. The laws of physics are such that the left-handed particles feel a different force from the right-handed particles. This is what leads to this parity violation.

(22:59) Now, it turns out that its challenging to write down mathematical theories that are consistent and have this property that left-handed particles and right-handed particles, experienced different forces. There are sort of loopholes that you have to jump through. Its called anomalies, or anomaly cancellation in quantum field theory. And these subtleties, these loopholes they come from, at least in certain ways of calculating the fact that space is continuous, you only see these loopholes when spaces, or these requirements when space is continuous. So the lattice knows nothing about this. The lattice knows nothing about these fancy anomalies.

(23:36) But you cant write down an inconsistent theory on the lattice. So somehow, the lattice has to cover its ass, it has to make sure that whatever it gives you is a consistent theory. And the way it does that is just by not allowing theories where left-handed and right-handed particles feel different forces.

Strogatz (23:50): All right, I think I get the flavor of it. Its something like that topology allows for some of the phenomena, these anomalies that are required to see what we see in the case of the weak force, that a discrete space would not permit. That something about the continuum is key.

Tong (24:06): You said it better than me, actually. Its all to do with topology. Thats exactly right. Yeah.

Strogatz (24:11): All right. Good. Thats a very nice segue for us actually, into where I was hoping we could go next, which is to talk about what quantum field theory has done for mathematics, because that is another one of the great success stories. Although, you know, for physicists who care about the universe, thats maybe not a primary concern, but for people in, in mathematics, were very grateful and also mystified at the great contributions that have been made by thinking about purely mathematical objects, as if they were informing them with insights from quantum field theory. Could you just tell us a little about some of that story starting, say, in the 1990s?

Tong (24:48): Yeah, this is really one of the wonderful things that come out of quantum field theory. And theres no small irony here. You know, the irony is that were using these mathematical techniques that mathematicians are extremely suspicious about because they dont think that, that theyre, theyre not rigorous. And yet at the same time, were sort of somehow able to leapfrog mathematicians and almost beat them at their own game in certain circumstances, where we can turn around and hand them results that theyre interested in, in their own area of specialty, and results that in some circumstances have utterly transformed some areas of mathematics.

(25:22) So I can try to give you some sense about how this works. The kind of area of mathematics that this has been most useful in is ideas to do with geometry. Its not the only one. But its, I think its the one that weve made most progress in thinking about as physicists. And of course, geometry has always been close to the heart of physicists. Einsteins theory of general relativity is really telling us that space and time are themselves some geometric object. So that what we do is we take what mathematicians call a manifold, its some geometric space. In your mind, you can think, firstly, of the surface of a soccer ball. And then maybe if the surface of a doughnut, where theres a hole in the middle. And then generalize to the surface of a pretzel, where theres a few holes in the middle. And then the big step is to take all of that and push it to some higher dimensions and think of some higher dimensional object with wrapped around on itself with higher dimensional holes, and, and so on.

(26:13) And so the kinds of questions mathematicians are asking us to classify objects like this, to ask whats special about different objects, what kind of holes they can have, the structures they can have on them, and so forth. And as physicists, we sort of come with some extra intuition.

(26:28) But in addition, we have this secret weapon of quantum field theory. We sort of have two secret weapons. We have quantum field theory; we have a willful disregard for rigor. Those two combine quite, quite nicely. And so we will ask questions like, take one of these spaces, and put a particle on it, and ask how does that particle respond to the space? Now with the particles or quantum particles, something quite interesting happens because it has a wave of probability which spreads over the space. And so because of this quantum nature, it has the option to sort of know about the global nature of the space. It can sort of feel out all of the space at once and figure out where the holes are and where the valleys are and where the peaks are. And so our quantum particles can do things like get stuck in certain holes. And in that way, tell us something about the topology of the spaces.

(27:18) So theres been a number of very major successes of applying quantum field theory to this one of the biggest ones was in the early 1990s, something called mirror symmetry, which revolutionized an area called symplectic geometry. A little later [Nathan] Seiberg and [Edward] Witten solved a particular four-dimensional quantum field theory, and that gave new insights into topology of four-dimensional spaces. Its really been a wonderfully fruitful program, where whats been happening for several decades now is physicists will come up with new ideas from quantum field theory, but utterly unable to prove them typically, because of this lack of rigor. And then mathematicians will come along, but its not just dotting eyes and crossing Ts, they typically take the ideas and they prove them in their own way, and introduce new ideas.

(28:02) And those new ideas are then feeding back into quantum field theory. And so theres been this really wonderful harmonious development between mathematics and physics. As it turns out, that were often asking the same questions, but using very different tools, and by talking to each other have made much more progress than we otherwise would have done.

Strogatz (28:18): I think the intuitive picture that you gave is very helpful that somehow thinking about this concept of a quantum field as something that is delocalized. You know, rather than a particle that we think of as point-like, you have this object that spreads over the whole of space and time, if theres time in the theory, or if were just doing geometry, I guess were just thinking of it as spreading over the whole of the space. These quantum fields are very neatly suited to detecting global features, as you said.

(28:47) And thats not a standard way of thinking in math. Were used to thinking a point and the neighborhood of a point, the infinitesimal neighborhood of a point. Thats our friend. Were like the most myopic creatures as mathematicians, whereas the physicists are so used to thinking of these automatically global sensing objects, these fields that can, as you say, sniff out the contours, the valleys, the peaks, the wholes of surfaces of global objects.

Tong (29:14): Yeah, thats exactly right. And part of the feedback into physics has been very important. So appreciating that topology is really underlying a lot of our ways of thinking in quantum field theory that we should think globally in quantum field theory as well as in, in geometry. And, you know, there are programs, for example, to build quantum computers and one of the most, well, perhaps its one of the more optimistic ways to build quantum computers.

(29:34) But if it could be made to work, one of the most powerful ways of building a quantum computer is to use topological ideas of quantum field theory, where information isnt stored in a local point but its stored globally over a space. The benefit being that if you nudge it somewhere at a point, you dont destroy the information because its not stored at one point. Its stored everywhere at once. So as I said, theres this really this wonderful interplay between mathematics and physics that Its happening as we speak.

Strogatz (30:01): Well, lets shift gears one last time back away from mathematics toward physics again, and maybe even a little bit of cosmology. So with regard to the success story of the physical theory, more of the constellation of theories that we call quantum field theory, weve had these experiments fairly recently at CERN. Is this, thats where the Large Hadron Collider is, is that right?

Tong (30:01): Thats right. Its in Geneva.

Strogatz (30:04): Okay. You mentioned about the discovery of the Higgs long predicted something like 50, 60 years ago, but its my understanding that physicists have been well, whats the right word? Disappointed, chagrined, puzzled. That some of the things that theyd hoped to see in the experiments at the Large Hadron Collider have not materialized. Supersymmetry, say, being one. Tell us a little about that story. Where are we hoping to see more from those experiments? How should we feel about not seeing more?

Tong (30:53): We were hoping to see more. I have no idea how we should feel though, that we havent seen. I could, I can tell you the story.

Tong (31:00): So the LHC was built. And it was built with the expectation that it would discover the Higgs boson, which it did. The Higgs boson was the last part of the Standard Model. And there were reasons to think that once we completed the Standard Model, the Higgs boson would also be the portal that led us to what comes next, the next layer of reality that what comes afterwards. And there are arguments that you can make, that when you discover the Higgs, you should discover sort of around in the same neighborhood, the same energy scale as the Higgs, some other particles that somehow stabilize the Higgs boson. The Higgs boson is special. Its the only particle in the Standard Model that doesnt spin. All other particles, the electron spins, the photon spins, its what we call the polarization. The Higgs boson is the only particle that doesnt spin. In some sense, its the simplest particle in the Standard Model.

(31:00) But there are arguments theoretical arguments that say that a particle that doesnt spin should have a very heavy mass. Very heavy means pushed up to the highest energy scale possible. These arguments are good arguments. We could use quantum field theory in many other situations, in materials described by quantum field theory. Its always true that if a particle doesnt spin, its called a scalar particle. And its got a light mass. Theres a reason why its masses light.

(32:25) And so we expected there to be a reason why the Higgs boson had the mass that it has. And we thought that reason would come with some extra particles that will sort of appear once the Higgs appeared. And maybe it was supersymmetry and maybe it was something called technicolor. And there were many, many theories out there. And we discovered the Higgs and the LHC I think this is important to add has exceeded all expectations when it comes to the operation of the machine and the experiments and the sensitivity of the detectors. And these people are absolute heroes who are doing the experiment.

(32:56) And the answer is theres just nothing else there at the energy scale that were currently exploring. And thats a puzzle. Its a puzzle to me. And its a puzzle to many others. We were clearly wrong; we were clearly wrong about the expectation that we should discover something new. But we dont know why were wrong. You know, we dont know what was wrong with those arguments. They still feel right, they still feel right to me. So theres something that were missing about quantum field theory, which is exciting. And you know, its good to be wrong in this area of science, because its only when youre wrong, you can finally be pushed in the right direction. But its fair to say that were not currently sure why were wrong.

Strogatz (33:32): Thats a good attitude to have, right, that so much progress has been made from these paradoxes, from what feels like disappointments at the time. But to be living through it and to be in a generation I mean, well, I dont want to say you could be washed up by the time this is figured out, but its a scary prospect.

Tong (33:50): Washed up would be fine. But Id like to be alive.

Strogatz (33:56): Yeah, I felt bad even saying that.

Going from the small to the big, why dont we think about some of the cosmological issues. Because some of the other great mysteries, things like dark matter, dark energy, the early universe. So you study as one of your own areas of great interest, the time right after the Big Bang, when we didnt really have particles yet. We just had, what, quantum fields?

Tong (34:22): There was a time after the Big Bang called inflation. So it was a time at which the universe expanded very, very rapidly. And there were quantum fields in the universe when this was happening. And what I think is really one of the most astonishing stories in all of science is that these quantum fields had fluctuations. Theyre always bouncing up and down, just because of quantum jitters, you know. Just as the Heisenberg uncertainty principle says a particle cant, cant be in a specific place because it will have infinite momentum, so you know, its always some uncertainty there. That the same is true for these fields. These quantum fields cant be exactly zero or exactly some value. Theyre always jittering up and down through quantum uncertainty.

(35:02) And what happened in these first few seconds seconds is way too long. First few 10-30 seconds, lets say, of the Big Bang is the universe expanded very rapidly. And these quantum fields sort of got caught in the act, that they were fluctuating, but then the universe dragged them apart to vast scales. And those fluctuations got stuck there. They couldnt fluctuate anymore, basically, because of causality reasons, because now they were spread so far that, you know, one part of the fluctuation didnt know what the other one was doing. So these fluctuations get stretched across the whole universe, way back in the day.

(35:43) And the wonderful story is that we can see them, we can see them now. And weve taken a photograph of them. So the photograph has a terrible name. Its called the cosmic microwave background radiation. You know this photograph, its the blue and red ripples. But its a photograph of the fireball that filled the universe 13.8 billion years ago, and theres ripples in there. And the ripples that we can see were seeded by these quantum fluctuations in the first few fractions of a second after the Big Bang. And we can do the calculation, you can calculate what the quantum fluctuations look like. And you can experimentally measure the fluctuations in the CMB. And they just agree. So its an astonishing story that we can take a photograph of these fluctuations.

(36:30) But theres also a level of disappointment here as well. The fluctuations that we see are fairly vanilla, theyre just those that you would get from free fields. And it would be nice if we could get more information, if we could see the statistical name is that the fluctuations are Gaussian. And it would be nice to see some non-Gaussianity, which will be telling us about the interactions between the fields back in the very, very early universe. And so again, the Planck satellite has, has flown and it has taken a snapshot of the CMB in ever clearer detail, and the non-Gaussianities that are there, if there are any there at all, are just smaller than, than the Planck satellite can detect.

(36:52) So theres hope for the future that theres other CMB experiments, theres also a hope that these non-Gaussianities might show up in the way that galaxies form, the statistical distribution of galaxies through the universe also holds a memory of these fluctuations that much we know is true, but that perhaps we might get more information from there. So it really is incredible that you can trace these fluctuations for 14 billion years, from the very earliest stages to the way the galaxies are distributed in the universe now,

Strogatz (37:36): Well, thats given me a lot of insight that I didnt have before about the imprint of these quantum fluctuations on the cosmic microwave background. Id always wondered. You mentioned that its the free theory, meaning what, tell us whats free means exactly? Theres no nothing right? I mean, its just, its the vacuum itself?

Tong (37:45): Its not just the vacuum, because these fields get excited as the universe expands. But its just a field that isnt interacting with any other fields or even with itself, its just bouncing up and down like a harmonic oscillator, basically. Each point is bouncing up and down like a spring. So its kind of the most boring field that you could imagine.

Strogatz (38:11): And so that means we didnt have to postulate any particular quantum field at the beginning of the universe. Its just, thats what you say, vanilla.

Tong (38:19): Its vanilla. So it would have been nice to get a better handle that these interactions are happening, or these interactions are happening, or the field had this particular property. And that doesnt seem maybe in the future, but at the moment, were not there yet.

Strogatz (38:32): So maybe we should then close with your personal hopes. Is there one, if you had to single out one thing that you would like to see solved personally, in the next few years, or for the future of research in quantum field theory, what would be your favorite? If you could dream.

Tong (38:48): There are so many

Strogatz: You can pick more.

Tong: Theres things on the mathematical side. So I would, I would love to understand, on the mathematical side, more about this Nielsen-Ninomiya theorem, the fact that you cannot discretize certain quantum field theories. And are there loopholes in the theorem? Are there assumptions we can throw out and somehow succeed in doing it?

(39:07) You know, theorems in physics, theyre usually called no-go theorems. You cant do this. But theyre often signposts about where you should look, because a mathematical theorem is, obviously its true, but therefore, it comes with very strict assumptions. And so maybe you can throw out this assumption or that assumption and, and make progress on that. So its on the mathematical side, I would love to see progress on that.

(39:28) On the experimental side, any of the things that weve spoken about some new particle, new hints of what lies beyond. And we are seeing hints fairly regularly. The most recent one is that the mass of the W boson on your side of the Atlantic is different from the mass of the W boson on my side of the Atlantic and that, that seems weird. Hints about dark matter, or dark matter. Whatever it is, is made of quantum fields. Theres no doubt about that.

(39:53) And the dark energy that you alluded to that there are predictions is too strong a word but there are suggestions from quantum field theory. at all those fluctuations of quantum fields should be driving the expansion of the universe. But in a way thats way, way bigger than were actually seeing.

(40:07) So, so the same puzzle thats there with the Higgs. Why is the Higgs so light? Its also there with dark energy. Why is the cosmological acceleration of the universe so small compared to what we, we think it is. So its a slightly odd situation to be in. I mean, we have this theory. Its completely amazing. But its also clear there are things we really dont understand.

Strogatz (40:26): I just want to thank you, David Tong, for this really wide-ranging and fascinating conversation. Thanks a lot for joining me today.

Tong (40:33): My pleasure. Thanks very much.

Announcer (40:39): If you like The Joy of Why, check out the Quanta Magazine Science Podcast, hosted by me, Susan Valot, one of the producers of this show. Also tell your friends about this podcast and give us a like or follow where you listen. It helps people find The Joy of Why podcast.

Steve Strogatz (41:03): The Joy of Why is a podcast from Quanta Magazine, an editorially independent publication supported by the Simons Foundation. Funding decisions by the Simons Foundation have no influence on the selection of topics, guests, or other editorial decisions in this podcast or in Quanta Magazine. The Joy of Why is produced by Susan Valot and Polly Stryker. Our editors are John Rennie and Thomas Lin, with support by Matt Carlstrom, Annie Melchor and Leila Sloman. Our theme music was composed by Richie Johnson. Our logo is by Jackie King, and artwork for the episodes is by Michael Driver and Samuel Velasco. Im your host, Steve Strogatz. If you have any questions or comments for us, please email us at quanta@simonsfoundation.org. Thanks for listening.

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What Is Quantum Field Theory and Why Is It Incomplete? - Quanta Magazine

Many people have had paranormal experiences that they can't explain, while others are quick to dismiss that ghosts exist.

Ghosts are the visual essence of those who have died. You may not think about it, or you may not have ever told anyone because you're afraid of how they will respond.

While many seek professional help after seeing ghosts, most arent that fortunate, often telling their doctors or therapists, who mistake psychic vision for psychosis; the wrongful diagnosis, medication, and hospitalizations do more harm than they realize.

In many cultures all around the world and throughout history, there has been a long-standing belief that a person's spirit can survive after death, transcending beyond the physical world.

Ghosts have been part of religion, folklore, and even the arts. And people who have had near-death experiences have said there is life after death, along with highly sensitive individuals whose empathic abilities allow them to see beyond the physical realm.

Despite there being some instances where alleged apparitions have appeared in film or photographs, the truth is that ghosts may exist, and they may not exist we truly don't know.

RELATED: If You Know Things Before They Happen, You Have This Magical Brain Quirk

With ghosts such a prevalent part of entertainment (shows like "Ghost Hunters" and movies like "Paranormal Activity"), it's no surprise that 46% of Americans believe in ghosts. But the reason may not have anything to do with the media we consume.

The main reason people believe in ghosts is because of having an experience with the paranormal. Perhaps they are sensitive to otherworldly presences, they grew up in a home that was said to be haunted, or have captured spirits on film.

The good news is if you're one of the people who can see ghosts or sense this type of energy, we're scientifically beginning to understand how seeing a ghost may be possible.

You see, whats happening is a paradigm shift in psychology. The same kind of shift that happened in physics after the discoveries in quantum physics. Its just that its taken psychology over a century to catch up, and really, the shift is only now beginning.

Well, the mainstream field of psychology has been based on the old (19th century and before) materialistic view of the world, that this material plane of reality is the only reality. This is what is referred to as old Newtonian physics.

And this is what most of us learned in school: that there are smaller and smaller physical building blocks out of which we are made. In fact, particle physicists specialize in hunting down and then finding smaller and smaller particles.

On the other hand, the new psychology is based on a more quantum understanding of the world, the view ushered in when quantum physics was born in the early 1920s. This is the science that is starting to help us understand that there is much more to our world that we cant see (estimated between 93-99.9999 percent of reality), than what we can see.

For a clue as to how this is possible, consider that the visible part of the electromagnetic light spectrum is just a tiny sliver of the entire range of frequencies of light.

The visible portion is what we see in a rainbow, the red to violet light. Slower or faster vibration than that, and we cant see it. (It's kind of like how dogs hear sounds we dont hear, or hear sounds that too are out of our range).

What were those discoveries that led to more quantum physics? And how is this related to ghosts?

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RELATED: 6 Signs A Spirit Is Trying To Warn You

Kind of like when we have an adult and a young kid nature inside of us. Sometimes we behave more like the child, and sometimes we behave more like the adult.

It's the same with light. Sometimes it behaves more like we would expect a wave of light to move, but at other times, it looks more as if it were a particle or photon of light.

Apparently, when we decide it moves like a wave, it does. When we decide its a particle, it is. This was called the observer effect, and launched a wave of new science, which began to take into account the role that our human consciousness plays in the creation of a physical reality.

The implications of this are huge, including how important each of us is in creating this world.

Even more mind-blowing is the finding that the observer effect works not only forward, but also backward in time. (And that both time and space are not absolute laws of nature that we once believed.)

This wave aspect is really about moving energy, and the patterns created when energy moves (look to the sky when a storm is forming, especially a tornado or hurricane, to get a deeper hint of this).

As it turns out, these wave patterns serve as a design template for the construction of the particle.

If you want to see a really great example, watch the video of cymatics, the work of Dr. Hans Jenny and his followers, and see how sound waves make patterns in various materials.

Now, realize that you have a wave-particle dual self, and that your wave self, the part of you that evidently exists first, is used as a template to make your body self. Starting to see what ghosts might really be?

Its possible that ghosts are the wave essence of a human being. The body may be gone, but the energy waves live on.

And this wave pattern may be what some of you can see, who have clairvoyant sight. Furthermore, those who experience clairvoyance may simply be more gifted in detecting a broader bandwidth of energy frequencies than the rest of us.

Physicist William A. Tiller might call you higher consciousness because you have a greater channel capacity than most of us kind of like the latest and greatest cable television ever.

So, if you see ghosts, know you're not alone and that there are many more transpersonal psychotherapists out there who believe you. We know you're likely not "crazy," just quantum both in vision and in reality.

RELATED: How Cats Protect You And Your Home From Ghosts And Negative Spirits, Based On Their Fur Color

Valerie Varan, MS, LPC, NCC is a holistic counselor and coach, and the author of 'Living in a Quantum Reality: Using Quantum Physics and Psychology to Embrace Your Higher Consciousness.' Follow her on Facebook or learn more about her holistic psychotherapy practice on her website.

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What Science & Quantum Physics Say About Whether Or Not Ghosts Are Real - YourTango