Category Archives: Quantum Physics

Scientists have finally found traces of the axion, an elusive particle that rarely interacts with normal matter. The axion was first predicted over 40 years ago but has never been seen until now.

Scientists have suggested that dark matter, the invisible matter that permeates our universe, may be made of axions. But rather than finding a dark matter axion deep in outer space, researchers have discovered mathematical signatures of an axion in an exotic material here on Earth.

The newly discovered axion isn't quite a particle as we normally think of it: It acts as a wave of electrons in a supercooled material known as a semimetal. But the discovery could be the first step in addressing one of the major unsolved problems in particle physics.

Related: The 18 Biggest Unsolved Mysteries in Physics

The axion is a candidate for dark matter, since, just like dark matter, it can't really interact with regular matter. This aloofness also makes the axion, if it exists, extremely difficult to detect. This strange particle could also help solve a long-standing conundrum in physics known as "the strong CP problem." For some reason, the laws of physics seem to act the same on particles and their antimatter partners, even when their spatial coordinates are inverted.This phenomenon is known as charge-parity symmetry, but existing physics theory says there's no reason this symmetry has to exist. The unexpected symmetry can be explained by the existence of a special field; detecting an axion would prove that this field exists, solving this mystery.

Because scientists believe that the ghostly, neutral particle barely interacts with ordinary matter, they have assumed that it would be hard to detect using existing space telescopes. So the researchers decided to try something more down to Earth, using a strange material known as condensed matter.

Condensed-matter experiments like the one the researchers conducted have been used to "find" elusive predicted particles in several well-known cases, including that of the majorana fermion. The particles are not detected in the usual sense, but are instead found as collective vibrations in materials that behave and respond exactly as the particle would.

"The problem with looking at outer space is that you cannot control your experimental environment very well," said study co-author Johannes Gooth, a physicist at the Max Planck Institute for Chemical Physics of Solids in Germany. "You wait for an event to happen and try to detect it. I think one of the beautiful things of getting these concepts of high-energy physics into condensed matter is that you can actually do much more."

The research team worked with a Weyl semimetal, a special and strange material in which electrons behave as if they have no mass, don't interact with each other and are split into two types: right-handed and left-handed. The property of being either right- or left-handed is called chirality; chirality in Weyl semimetals is conserved, meaning there are equal numbers of right- and left-handed electrons. Cooling the semimetal to 12 degrees Fahrenheit (minus 11 degrees Celsius) allowed the electrons to interact and to condense themselves into a crystal of their own.

Waves of vibrations traveling through crystals are called phonons. Since the strange laws of quantum mechanics dictate that particles can also behave as waves, there are certain phonons that have the same properties as common quantum particles, such as electrons and photons. Gooth and his colleagues observed phonons in the electron crystal that responded to electric and magnetic fields exactly like axions are predicted to. These quasiparticles also did not have equal numbers of right- and left-handed particles. (Physicists also predicted that axions would break conservation of chirality.)

"It's encouraging that these equations [describing the axion] are so natural and compelling that they are realized in nature in at least one circumstance," said MIT theoretical physicist and Nobel laureate Frank Wilczek, who originally named the axion in 1977. "If we know that there are some materials that host axions, well, maybe the material we call space also houses axions." Wilczek, who was not involved in the current study, also suggested that a material like Weyl semimetal could one day be used as a kind of "antenna" for detecting fundamental axions, or axions that exist in their own right as particles in the universe, rather than as collective vibrations.

While the search for the axion as an independent, lone particle will continue, experiments like this help more traditional detection experiments by providing limits on and estimates of the particle's properties, such as mass. This gives other experimentalists a better idea of where to look for these particles. It also robustly demonstrates that the particle's existence is possible.

"A theory first is a mathematical concept," said Gooth. "And the beauty of these condensed-matter physics experiments is that we can show that this kind of mathematics exists in nature at all."

The research was published online Oct. 7 in the journal Nature.

Originally published on Live Science.

Editor's Note: This second paragraph of this story was updated at 10:05 a.m. E.D.T. to clarify that what was found in this study was a mathematical signature of an axion and not a dark matter axion found in space.

Here is the original post:

Physicists Have Finally Seen Traces of a Long-Sought Particle. Here's Why That's a Big Deal. - Livescience.com

Is our fundamental reality continuous or is it chopped up into tiny, discrete bits?

Asked another way, is space-time smooth or chunky? The question cuts to the heart of the most fundamental theories of physics, linking together the way space and time intersect with the material of our everyday existence.

However, experimentally testing the nature of space and time has been impossible, because of the extreme energies needed to probe such tiny scales in the universe. That is until now. A team of astronomers has proposed an ambitious new plan to use a fleet of tiny spacecraft to detect subtle changes in the speed of light, a hallmark of some of the most mind-bending theories of the cosmos. If space and time are indeed broken up into little bits, the research could pave the way for a completely new understanding of reality.

Related: The 18 Biggest Unsolved Mysteries in Physics

The question of "what is space and time?" goes back thousands of years, and our modern understanding rests on two strangely incompatible pillars: quantum mechanics and Einstein's theory of general relativity.

In general relativity, space and time are woven together into the unified fabric of space-time, the four-dimensional stage that underpins our universe. This space-time is continuous, which means that there are no gaps anywhere; it's all a smooth texture. Space-time isn't just a platform for us to act our parts, however; it's also a player too: The bending and warping of space-time gives us our experience of gravity.

Related: 8 Ways You Can See Einstein's Theory of Relativity in Real Life

In the opposite corner, a set of rules called quantum mechanics governs the interactions of the very tiny things in the universe. Quantum mechanics rests on the idea that not much of our everyday experience is smooth and continuous, but chunky. In other words, it's quantized. Energy, momentum, spin and so many other properties of matter come in only discrete little packets.

What's more, quantum mechanics itself also splits itself into two camps. On one hand, we have the familiar particles of our everyday existence, such as electrons and protons, that interact and do other interesting things. These are obviously very chunky, as they're discrete "things." On the other hand, we have the quantum fields. In the subatomic world, each kind of particle has its own field that spreads throughout space-time; when we think of particles, we think of little vibrations in their fields, which in turn interact with other particles, and do some other interesting things. The fields are understandably very smooth.

So, we have some smooth pictures of our universe and some chunky ones. When it comes to space-time itself, we can easily imagine extending the concepts of quantum mechanics all the way to their logical conclusion, and ruling that space and time are discrete: The very fabric of reality is divided up like pixels on a computer screen, and what we experience as smooth, continuous movement is nothing but a grid of discrete pixels at the tiniest of scales.

Related: The Illusion of Time: What's Real?

Many theories of merging together quantum mechanics and general relativity, like string theory and loop quantum gravity, predict some form of discrete space-time (although the precise predictions, interpretations and implications of that chunkiness are still poorly understood). If we could find evidence for discrete space-time, it would not only completely rewrite our understanding of reality, but also open the door to a revolution in physics.

This discreteness can reveal itself only in the most subtle ways; otherwise we would've spotted it by now. Various theories have predicted that if space-time were indeed chunky, then the speed of light may not be entirely constant it may shift ever so slightly depending on the energy of that light. Higher energy light has a shorter wavelength, and when the wavelength becomes small enough, it can "see" the chunkiness of spacetime. Imagine walking down sidewalk: with big feet you don't notice any small cracks or bumps, but if you had microscopic feet you would trip over every little imperfection, slowing you down. But this shift is incredibly tiny; if space-time is discrete, it's on a scale more than a billion times smaller than what we can currently probe in our most powerful experiments.

Enter GrailQuest: the Gamma-ray Astronomy International Laboratory for Quantum Exploration of Space-Time. A team of astronomers submitted a proposal for this mission in response to a call for new space-time-hunting ideas from the European Space Agency (ESA). Their proposal is detailed in the arXiv database, meaning that it hasn't yet been reviewed by peers in the field.

Here's the scoop: In order to see if the speed of light changes with different energies, we need to collect a huge amount of the highest-energy light in the universe, and GrailQuest hopes to do just that.

GrailQuest consists of a fleet of small, simple spacecraft (the exact number varies, from just a few dozen if the satellites are larger to well over a few thousand if they're smaller) to constantly monitor the sky for gamma-ray bursts. These are some of the most powerful explosions in the universe. Like their name suggests, these bursts release copious amounts of high-energy photons, a.k.a. gamma rays. These gamma rays travel across billions of years before reaching the fleet of spacecraft, which record the energy of the gamma rays and the differences in timings as the burst washes over the fleet.

With enough accuracy, GrailQuest might be able to reveal if space-time is discrete. At least, it has the right setup: It's examining the highest-energy light (which is affected the most in theories that predict that space-time is chunky); the gamma rays have been traveling for billions of light-years (allowing the effect to build up over time); and the spacecraft are simple enough to produce en masse (so the entire fleet can see as many events as possible, all across the sky).

How would our conceptions of reality change if GrailQuest were to find evidence for the discreteness of space-time? It's impossible to say our current theories are all over the map when it comes to implications. But no matter what, we're going to have to wait. This round of ESA proposals is for launches sometime between 2035 and 2050. While we're waiting, we can debate if the time elapsed between now and then is fundamentally smooth or chunky.

Paul M. Sutteris an astrophysicist at The Ohio State University, host of Ask a Spaceman and Space Radio, and author of Your Place in the Universe.

Originally published on Live Science.

Read the original here:

What If Space-Time Were 'Chunky'? It Would Forever Change the Nature of Reality. - Livescience.com

Its rather unfortunate that the education system not just in India but across the world ends up laying too much emphasis on securing good marks or landing good grades. However, its not always about the grades as a A tweet from a PhD student from University of California, Berkeley highlighted. The tweet received a surprising mention from none other than Google CEO Sundar Pichai. Saraphina Nance, who is an astrophysics student, two days back tweeted about an incident on how she scored 0 on a quantum physics exam. She tweeted, 4 years ago I got a 0 on a quantum physics exam. i met with my professor fearing i needed to change my major & quit physics. today, im in a top tier astrophysics Ph.D program & published 2 papers. STEM is hard for everyonegrades dont mean youre not good enough to do it.'; var randomNumber = Math.random(); var isIndia = (window.geoinfo && window.geoinfo.CountryCode === 'IN') && (window.location.href.indexOf('outsideindia') === -1 ); console.log(isIndia && randomNumber The tweet caught the attention of Sundar Pichai, who replied to her tweet and said, well said, and so inspiring. Last year Pichai had shared his views on education in an article for NBC News. We should make sure that the next generation of jobs are good jobs, in every sense, Pichai wrote. Rather than thinking of education as the opening act, we need to make sure it's a constant, natural and simple act across life -- with lightweight, flexible courses, skills and programs available to everyone.He also said that with the advent of technology, it was vital to make education a continuous process. Pichai wrote, In the past, people were educated, and learned job skills, and that was enough for a lifetime. Now, with technology changing rapidly and new job areas emerging and transforming constantly, thats no longer the case. We need to focus on making lightweight, continuous education widely available. This is just as crucial to making sure that everyone can find opportunities in the future workplace.

Continue reading here:

Google CEO Sundar Pichai is inspired by a woman who scored a 0 in her physics exam - Times of India

In the Standard Model, the neutron's electric dipole moment is predicted to be a factor of ten... [+] billion larger than our observational limits show. The only explanation is that somehow, something beyond the Standard Model is protecting this CP symmetry in the strong interactions. We can demonstrate a lot of things in science, but proving that CP is conserved in the strong interactions can never be done. However, solving the strong CP problem may be closer on the horizon than almost anyone realizes.

If you ask a physicist what the biggest unsolved problem facing the field today is, you're likely to get a variety of answers. Some will point to the hierarchy problem, wondering why the masses of the Standard Model particles have the (small) values we observe. Others will ask about baryogenesis, asking why the Universe is filled with matter but not antimatter. Other popular answers are just as puzzling: dark matter, dark energy, quantum gravity, the origin of the Universe, and whether there's an ultimate theory of everything for us to discover.

But one puzzle that never gets the attention it deserves has been known for nearly half a century: the strong CP problem. Unlike most of the problems that demand new physics that goes beyond the Standard Model, the strong CP problem is a problem with the Standard Model itself. Here's the lowdown on a problem everyone should be paying more attention to.

The Standard Model of particle physics accounts for three of the four forces (excepting gravity),... [+] the full suite of discovered particles, and all of their interactions. Whether there are additional particles and/or interactions that are discoverable with colliders we can build on Earth is a debatable subject, but there are still many puzzles that remain unanswered, such as the observed absence of strong CP violation, with the Standard Model in its current form.

When most of us think of the Standard Model, we think about the fundamental particles that make up the Universe and the interactions that occur between them. On the particle side, we have the quarks and leptons, along with the force-carrying particles that govern the electromagnetic, weak, and strong interactions.

There are six types of quarks (and antiquarks), each with electric and color charges, and six types of leptons (and anti-leptons), three of which have electric charges (like the electron and its heavier cousins) and three of which don't (the neutrinos). But whereas the electromagnetic force only has one force-carrying particle associated with it (the photon), the weak nuclear force and the strong nuclear force have many: three gauge bosons (the W+, W- and Z) for the weak interaction and eight of them (the eight different gluons) for the strong interaction.

The particles and antiparticles of the Standard Model have now all been directly detected, with the... [+] last holdout, the Higgs Boson, falling at the LHC earlier this decade. All of these particles can be created at LHC energies, and the masses of the particles lead to fundamental constants that are absolutely necessary to describe them fully. These particles can be well-described by the physics of the quantum field theories underlying the Standard Model, but they do not describe everything, like dark matter, or why there is no CP violation in the strong interactions.

Why so many? This is where things get interesting. In most of the conventional mathematics we use, including most of the mathematics we use to model simple physical systems, all the operations are what we call commutative. Simply put, commutative means it doesn't matter what order you do your operations in. 2 + 3 is the same as 3 + 2, and 5 * 8 is the same as 8 * 5; both are commutative.

But other things fundamentally don't commute. For example, take your cellphone and hold it so that the screen is facing your face. Now, try doing each of the following two things:

The same two rotations, but in the opposite order, lead to a wildly different end result.

The author's last cellphone in the pre-smartphone era exemplifies how rotations in 3D space do not... [+] commute. At left, the top and bottom rows begin in the same configuration. At top, a 90 degree counterclockwise rotation in the plane of the photograph is followed by a 90 degree clockwise rotation around the vertical axis. At bottom, the same two rotations are performed but in the opposite order. This demonstrates the non-commutativity of rotations.

When it comes to the Standard Model, the interactions we use are a little more mathematically complicated than addition, multiplication, or even rotations, but the concept is the same. Instead of talking about whether a set of operations is commutative or non-commutative, we talk about whether the group (from mathematical group theory) describing these interactions is abelian or non-abelian, named after the great mathematician Niels Abel.

In the Standard Model, electromagnetism is simply abelian, while the nuclear forces, both weak and strong, are non-abelian. Instead of addition, multiplication, or rotations, the difference between abelian and non-abelian shows up in symmetries. Abelian theories shouldhave interactions that are symmetric under:

while non-abelian theories should show differences.

Unstable particles, like the big red particle pictured above, will decay through either the strong,... [+] electromagnetic, or weak interactions, producing 'daughter' particles when they do. If the process that occurs in our Universe occurs at a different rate or with different properties if you look at the mirror-image decay process, that violates Parity, or P-symmetry. If the mirrored process is the same in all ways, then P-symmetry is conserved. Replacing particles with antiparticles is a test of C-symmetry, while doing both simultaneously is a test of CP-symmetry.

For the electromagnetic interactions, C, P, and T are all individually conserved, and are also conserved in any combination (CP, PT, CT, and CPT). For the weak interactions, C, P, and T have all been found to be violated individually, as are the combinations of any two (CP, PT, and CT) but not all three together (CPT).

This is where the problem comes in. In the Standard Model, certain interactions are forbidden, while others are allowed. For the electromagnetic interaction, violations of C, P, and T are all individually forbidden. For the weak and strong interactions, the violation of all three in tandem (CPT) is forbidden. But the combination of C and P together (CP), while allowed in both the weak and strong interactions, has only ever been seen in the weak interaction. The fact that it's allowed in the strong interaction, but not seen, is the strong CP problem.

Changing particles for antiparticles and reflecting them in a mirror simultaneously represents CP... [+] symmetry. If the anti-mirror decays are different from the normal decays, CP is violated. Time reversal symmetry, known as T, must also be violated if CP is violated. Nobody knows why CP violation, which is fully allowed to occur in both the strong and weak interactions in the Standard Model, only appears experimentally in the weak interactions.

Way back in 1956, when writing about quantum physics, Murray Gell-Mann coined what is now known as the totalitarian principle: "Everything not forbidden is compulsory." Although it's often woefully misinterpreted, it's 100% correct if we take it to mean that if there isn't a conservation law forbidding an interaction from occurring, then there is a finite, non-zero probability that this interaction will occur.

In the weak interactions, CP violation occurs at approximately the 1-in-1,000 level, and perhaps one would naively expect that it occurs in the strong interactions at approximately the same level. Yet we've looked for CP violation extensively and to no avail. If it does occur, it's suppressed by more than a factor of one billion (109), something so surprising that it would be unscientific to simply chalk this up to chance alone.

When we see something like a ball balanced precariously atop a hill, this appears to be what we call... [+] a finely-tuned state, or a state of unstable equilibrium. A much more stable position is for the ball to be down somewhere at the bottom of the valley. Whenever we encounter a finely-tuned physical situation, there are good reasons to seek a physically-motivated explanation for it.

If you've been trained in theoretical physics, your first instinct would be to propose a new symmetry that suppresses CP-violating terms in the strong interactions, and indeed physicists Roberto Peccei and Helen Quinn first concocted such a symmetry in 1977.Like most theories, it hypothesizes a new parameter (in this case, a new scalar field) to solve the problem. But unlike many toy models, this one can be put to the test.

If Peccei and Quinn's new idea were correct, it should predict the existence of a new particle: the axion. The axion should be extremely light, should have no charge, and should be extraordinarily abundant in number. It makes for a perfect dark matter candidate particle, in fact. And in 1983, theoretical physicist Pierre Sikivie* recognized that one of the consequences of such an axion would be that the right experiment could feasibly detect them right here in a terrestrial laboratory.

The cryogenic setup of one of the experiments looking to exploit the hypothetical interactions... [+] between dark matter and electromagnetism, focused on a low-mass candidate: the axion. Yet if dark matter doesn't have the specific properties that current experiments are testing for, none of the ones we've even imagined will ever see it directly: further motivation to seek out all the indirect evidence possible.

This marked the birth of what would become the Axion Dark Matter eXperiment (ADMX), which has been searching for axions for the past two decades. It has placed tremendously good constraints on the existence and properties of axions, ruling out the original formulation of Peccei and Quinn but leaving open the room that either an extended Peccei-Quinn symmetry or a number of quality alternatives could both solve the strong CP problem and lead to a compelling dark matter candidate.

As of 2019, no evidence for axions has been seen, but the constraints are better than ever and the experiment is presently being upgraded to search for numerous varieties of axion and axion-like particles. If even a fraction of the dark matter is made of such a particle, ADMX, leveraging (what I know as) a Sikivie cavity, will be the first to discover it directly.

As the ADMX detector is removed from its magnet, the liquid helium used to cool the experiment forms... [+] vapor. ADMX is the premiere experiment in the world dedicated to the search for axions as a potential dark matter candidate, motivated by a possible solution to the strong CP problem.

Earlier this month, it was announced that Pierre Sikivie will be the 2020 recipient of the Sakurai Prize,one of the most prestigious awards in physics. Yet despite the theoretical predictions surrounding the axion, the search for its existence and the quest to measure its properties, it's eminently possible that all of this is based on a compelling, beautiful, elegant, but non-physical idea.

The solution to the strong CP problem may not lie in a new symmetry akin to the one proposed by Peccei and Quinn, and axions (or axion-like particles) may not exist in our Universe at all. This is all the more reason to examine the Universe in every possible way at our technological disposal: in theoretical physics, there are a near-infinite number of possible solutions to any puzzle we can identify. Only through experiment and observation can we hope to discover which one applies to our Universe.

Our galaxy is thought to be embedded in an enormous, diffuse dark matter halo, indicating that there... [+] must be dark matter flowing through the solar system. Although we have yet to detect dark matter directly, the fact that it's all around us makes the possibility of detecting it, if we can surmise its properties correctly, a real possibility in the 21st century.

At almost every frontier in theoretical physics, scientists are struggling to explain what we observe. We don't know what composes dark matter; we don't know what's responsible for dark energy; we don't know how matter won out over antimatter in the early stages of the Universe. But the strong CP problem is different: it's a puzzle not because of something we observe, but because of the observed absence of something that's so thoroughly expected.

Why, in the strong interactions, do particles that decay match exactly the decays of antiparticles in a mirror-image configuration?Why does the neutron not have an electric dipole moment? Many alternative solutions to a new symmetry, such as one of the quarks being massless, are now ruled out. Does nature just exist this way,in defiance of our expectations?

Through the right developments in theoretical and experimental physics, and with a little help from nature, we just might find out.

* Author's disclosure: Pierre Sikivie was the author's professor and a member of his dissertation committee in graduate school during the early 2000s. Ethan Siegel claims no further conflict of interest.

View post:

The 'Strong CP Problem' Is The Most Underrated Puzzle In All Of Physics - Forbes

Physicists have long known of four fundamental forces of nature: gravity, electromagnetism, the strong nuclear force, and the weak nuclear force.

Now, they might have evidence of a fifth force.

The discovery of a fifth force of nature could help explain the mystery of dark matter, which is proposed to make up around 85 percent of the universe's mass. It could also pave the way for a unified fifth force theory, one that joins together electromagnetic, strong and weak nuclear forces as "manifestations of one grander, more fundamental force," as theoretical physicist Jonathan Feng put it in 2016.

The new findings build upon a study published in 2016 that offered the first hint of a fifth force.

In 2015, a team of physicists at Hungary's Institute for Nuclear Research was looking for "dark photons," which are hypothetical particles believed to "carry" dark matter. To catch a glimpse of these strange forces at work, the team used a particle accelerator to shoot particles through a vacuum tube at high speeds. The goal was to observe the way isotopes decay after thrust into high-energy states anomalies in the way particles behave could suggest the presence of unknown forces.

So, the team closely watched the radioactive decay of beryllium-8, an unstable isotope. When the particles from beryllium-8 decayed, the team observed unexpected light emissions: The electrons and positrons from the unstable isotope tended to burst away from each other at exactly 140 degrees. This shouldn't have happened, according to the law of conservation of energy. The results suggested that an unknown particle was created in the decay.

A team of researchers at the University of California, Irvine (UCI), proposed that the unknown particle was not a dark photon, but rather a boson specifically, a "protophobic X boson," which would be indicative of a fifth fundamental force. In simple terms, bosons are particles in quantum mechanics that carry energy, and function as the "glue" that holds matter together and controls the interactions between physical forces.

As Big Think's Robby Berman wrote in 2016:

"[In] the Standard Model of Physics, each of the four fundamental forces has a boson to go with it - the strong force has gluons, the electromagnetic force is carried by particles of light, or photons, and the weak force is carried by W and Z bosons. The new boson proposed by the UCI researchers is unlike others and as such may point to a new force. The new boson has the intriguing characteristic of interacting only with electrons and neutrons at short distances, while electromagnetic forces normally act on protons and electrons."

In the new paper, published on the preprint archive arXiv, the Hungarian team observed similar evidence for a new boson, which they refer to as the X17 particle, as its mass is calculated to be about 17 megaelectronvolts. This time, however, the observations come from the decay of an isotope of helium.

"This feature is similar to the anomaly observed in 8Be, and seems to be in agreement with the X17 boson decay scenario," the researchers wrote in their paper. "We are expecting more, independent experimental results to come for the X17 particle in the coming years."

The discovery of a fifth force of nature would provide a glimpse into the "dark sector", which in general describes yet-unobservable forces that can't readily be described by the Standard Model. Strangely, the subatomic particles in this hidden layer of our universe hardly interact with the more observable particles of the Standard Model.

A fifth force could scientists better understand how these two layers coexist.

"If true, it's revolutionary," Weng said in 2016. "For decades, we've known of four fundamental forces: gravitation, electromagnetism, and the strong and weak nuclear forces. If confirmed by further experiments, this discovery of a possible fifth force would completely change our understanding of the universe, with consequences for the unification of forces and dark matter."

Related Articles Around the Web

Link:

The X17 particle: Scientists may have discovered the fifth force of nature - Big Think

From the breakthroughs of Einstein and Dirac to contemporary physicists and mathematicians who are shedding light on the blossoming and revolutionary interaction between mathematics and physics, Graham Farmelos new book takes readers on an adventure through the two fields relationship.

Farmelo, a renowned physicist and writer, led a discussion surrounding topics covered in his book, The Universe Speaks in Numbers: How Modern Maths Reveals Natures Deepest Secrets, Nov. 14 at Snell Engineering Center. Farmelo is a fellow at Churchill College at the University of Cambridge as well as an affiliated professor at Northeastern.

Nima Arkani-Hamed, one of the nations leading theoretical physicists and a professor in the School of Natural Sciences at the Institute for Advanced Study in Princeton, New Jersey, was Farmelos guest speaker for the event. He arrived a couple of minutes late to the event and still received a round of applause from the audience as he walked through the door.

The talk began with Farmelo introducing Arkani-Hamed as the best theoretical physicist ever produced by McDonalds, referencing the fact that Arkani-Hamed had worked two summers in the fast-food chain in his youth.

Arkani-Hamed explained that within the independent development in physics and mathematics, theres more and more understanding of the deep and mysterious relationship between them. He said order can be made of our seemingly chaotic world and could be captured in succinct mathematical language.

Farmelo shared some of the foundational history of the field, beginning with Sir Isaac Newton, most well-known for his development of the three laws of motion. Farmelo explained that Newton wouldve never described himself as a theoretical physicist. Newton became one of the first to think that physicists should aim to make predictions about the world and that they could do so using defined mathematical calculations.

This proposal was a radical agenda for the scientific community at the time, though it has since laid the foundation for the impetus of physics that was to follow, Farmelo said.

Arkani-Hamed then interjected, saying one of his pet peeves is when people talk about theorists who are proven to be wrong about a certain theory, as if they are completely dumb, irrational or illogical for thinking that way.

He gave the example of the theory of luminiferous ether, a hypothetical medium for transmitting light and radiation, filling all unoccupied space. Ultimately, Einsteins theory of relativity eliminated the need for a light-transmitting medium, disproving the existence of the ether.

The luminiferous ether was a concept proposed by Newton who is, as aforementioned, a world-renowned physicist. Though Newton build the wrong scaffolding, it still lent way to the correct equations eventually, Arkani-Hamed said.

According to Arkani-Hamed, quantum mechanics is the most revolutionary theory of the 20th century. Put simply, quantum mechanics is the application of quantum theory: the theoretical basis of modern physics that explains the nature and behavior of matter and energy on the atomic and subatomic level.

To give an example of how mathematics and physics are intrinsically intertwined, Farmelo and Arkani-Hamed talked about how British physicist Paul Diracs work gave way to something once thought unfeasible.

In 1928, Dirac wrote an equation that combined quantum theory and special relativity to describe the behavior of an electron moving at a relativistic speed. This equation posed a problem in the classical physics practice. Even Einstein is known to have said he couldnt imagine any points of intersection between these two fundamental theories.

Dirac proposed the concept of antiparticles, which are particles that have all the same qualities as another particle but have an opposite electrical charge. This is the only way known to current physicists on how to successfully marry the theories of quantum mechanics and special relativity.

This intersection between two outrageously different theories is a relatively new revelation in the field of physics, and speaks to the deep, intricate and seemingly ever-growing connection between the worlds of mathematics and physics.

There is a giant Truth with a capital T of the world out there that physics is constantly working towards, that is also somehow enlaced with a giant Truth with a capital T of the mathematical world, Arkani-Hamed said.

Both Farmelo and Arkani-Hamed said they are excited by the impact of these two fields work in collaboration and believe there is much more to discover from their combination.

We dont actually know what reality is about. We are still learning, and we have to go into it with an open mind. Often, what we predict or assume something to be, can more easily be proven wrong than proven right, Arkani-Hamed said.

Read more here:

The Universe Speaks in Numbers: The deep relationship between math and physics - The Huntington News

Michael Inkpen underwent treatment for lymphoma, played indie rock and studied chemistry internationally before joining USC Dornsife. [4 min read]

While making scientific inroads to molecular electronics and energy storage, chemist Michael Inkpen also aims to be a science communicator. (Photo: Rhonda Hillbery.)

Ten years ago, Michael Inkpen had a busy schedule, shuttling from the chemistry lab where he pursued his Ph.D. studies by day to the London clubs and bars where he performed with an indie rock band well into the night. That changed abruptly when one day he felt a lump in his neck.

In retrospect, Inkpen sees something worthwhile in the life-interrupting diagnosis of Hodgkin lymphoma that followed. His cancer turned out to be highly treatable, and experiencing serious illness firsthand elicited a philosophical outlook that has stuck with him in the years since.

Life is too short to get hung up on small things, said Inkpen, assistant professor of chemistry at the USC Dornsife College of Letters, Arts and Sciences. It was a humbling journey, realizing that youre essentially just a bag of water, and amazing, really, that youre here at all.

After chemotherapy and radiation treatment, Inkpens cancer was in remission. He returned to juggling chemistry and club gigs before ultimately pulling back from performing to focus entirely on earning his Ph.D. Then, after a postdoctoral stint at Imperial College in the U.K., he spent two years at Columbia University in New York and one year at the University of Rennes 1 in France on an EU-funded Marie Skodowska-Curie Postdoctoral Global Individual Fellowship. This past January, his path led to Los Angeles, where he joined USC Dornsife and set about designing his own lab.

Moving to Los Angeles and joining USC offered a dream opportunity to design and build my own independent lab and create a research group at a top university in a world-class city, Inkpen said.

Building blocks

Inkpens research is located at the interface of chemistry and physics; his goal is to better understand how molecular systems can be used to transport electric charges. Building on his interdisciplinary training, he aims to both synthesize new materials and then study their properties by connecting them between tiny, nanoscale electrodes.

His approach is reminiscent of LEGO bricks he explores relationships between individual molecular building blocks and their extended, assembled chemical structures in one, two and three dimensions. This research might eventually bring about insights into and breakthroughs in energy storage or molecular-scale electronics.

Moores Law famously predicted in the 1960s that improvements in microchip transistor manufacturing would yield ever smaller components, resulting in steadily increasing computing capability. This principle has so far held true, as seen in todays compact, more powerful devices. (Think smartphones.)

If you extrapolate Moores Law, you eventually get to molecular-sized circuit components, Inkpen said. In addition to their small size, molecular components are highly customizable and demonstrate unique properties tied to quantum mechanics. Today there is growing interest in exploring what molecules can do that traditional silicon-based technologies cannot.

Inkpen is particularly interested in how the introduction of positive or negative charges may change the electronic properties of materials. This is akin to how charging a balloon by rubbing it against hair will let it stick to a wall, whereas, demonstrating a different behavior, an uncharged balloon simply falls to the ground.

Scientific storytelling

Beyond the science itself, Inkpen is fascinated by how science can be shared with diverse audiences in innovative, creative ways. Human connection is important in science, he said, and the desire for it is what led him to cofound a band so many years ago.

The Ph.D. can sometimes be a lonely business, particularly when your experiments arent working out and you dont know why, Inkpen said. Writing songs and gigging was fun, and provided a healthy counterpoint to long hours at the chemistry bench.

Today, Inkpen attends science cafes and follows science bloggers and vloggers, including Derek Lowe of In The Pipeline, Dianna Cowern of Physics Girl, and the University of Nottinghams Periodic Videos. Inkpen is a fan of the late physicist Richard Feynman, legendary for popularizing science in unique ways as well as for bongo drumming. Feynman, a Nobel laureate, published accessible works on the philosophy of science and delivered TV interviews and lectures in a timeless, inimitable style.

These scientific rock stars didnt stay in their ivory towers doing experiments, they embraced unconventional approaches to show millions of people why what they do, and how they think, is fascinating and relevant, Inkpen said.

Its no surprise that besides teaching and mentoring graduate students, Inkpen enjoys occasionally blogging about chemistry and life as a researcher and plans to boost his involvement in science outreach to K-12 and underserved college populations.

For me, being a scientist is not only about the results and hard data; you are part of a community, he said. I have frequently been inspired over the years by captivating school experiments, science documentaries, blog posts or even simple tweets, and I am determined to pay it forward.

See the original post here:

Cancer experience inspires chemist both as a researcher and a science communicator > News > USC Dornsife - USC Dornsife College of Letters, Arts...

Chunky Or Smooth?

A team of astronomers has a plan to launch a massive swarm of tiny spacecraft and investigate the fabric of our reality.

The mission, GrailQuest, aims to settle a longstanding debate among physicists, according to Live Science: whether spacetime is the continuous fabric described by general relativity or the chunky, pixelated jumble of discrete objects described by quantum mechanics. If it pans out, it could completely upend our understanding of the universe.

GrailQuest is still in its early stages Live Science reports that the fleet of satellites would launch sometime between 2035 and 2050, so we have plenty of time before we have to rewrite the physics textbooks.

At the moment, the project exists as a European Space Agency proposal shared to the preprint server ArXiv. The size and number of satellites hasnt been sorted out yet, but the idea is to position them in a wide array so that they can measure gamma rays that have been hurtling through space for billions of years.

If those measurements suggest that the speed of those light rays has shifted away from the, well, speed of light, then it could be interpreted as evidence that spacetime is discrete. If not, then it would support the smooth fabric hypothesis.

But part of the challenge is equipping the spacecraft with sensitive enough equipment to spot the difference Live Science reports that theyll have to be a billion times more sensitive than todays best sensors.

READ MORE: What If Space-Time Were Chunky? It Would Forever Change the Nature of Reality. [Live Science]

More on spacetime: Bizarre Black Hole Drags Spacetime, Blasts Wobbling Plasma Jets

Continued here:

Satellite Mission Will Investigate Whether Reality Is Pixelated - Futurism

If you could look closely enough at the objects that surround you, zooming in at magnifications far beyond those you could ever see with most microscopes, you would eventually get to a point where the familiar rules of your everyday experiences break down. At scales where blood cells and viruses seem enormous and molecules come into view, things are no longer subject to the simple laws of physics that we learn in high school.

Atomsand the electrons, protons and neutrons they are made ofdont exist in the same way a marble does. Instead they are smeared in clouds that are difficult to understand and impossible to describe without the complex mathematics of quantum mechanics.

And yet atoms make up molecules, which, in turn, are the building blocks of marbles and everything else we touch and see each day. Nature has clearly found some way of suppressing quantum behavior when quantum objects are assembled into the familiar ones all around us.

How can things that obey the classical laws of physicssuch as a pitched baseball or a bumblebee in flightbe composed of parts that are subject to quantum rules at minute levels? That is one of the deepest questions in modern physics. In pursuit of an answer, recent researchwith funding from the High Energy Physics program at the Department of Energys Office of Scienceshould help shed light on how the classical world emerges from the underlying quantum one.

A quantum-computing algorithm, developed by scientists at Los Alamos National Laboratory and the University of California, Davisincluding both of usopens a new window on the connection between the quantum and classical worlds and the transition that must occur as we zoom out from the smallest scales.

To study the quantum-to-classical transition, physicists need to evaluate how close a quantum system is to acting classically. Among other effects, physicists must consider the fact that quantum objects are subject to wave-particle duality. Things we often think of as particles, such electrons, can act like waves in some circumstances. And things we think of as waves, such as light, can act like particles, which are called photons. In a quantum system, the wavelike states of particles can interfere with one another in much the same way that ocean waves can sometimes add together or cancel one another out.

A quantum system lacking interference can be described using classical rules rather than quantum ones. The newly developed algorithm searches out interference-free solutions, known as consistent histories, which are those we ultimately observe in the classical world we inhabit.

For systems of a few atoms, finding consistent histories is fairly trivial. For systems made up of many pieces, however, quantum-to-classical transition calculations are notoriously difficult to solve. The number of equations involved grows drastically with each added atom. In fact, for systems of more than just a few atoms, calculations rapidly become intractable on even the most powerful supercomputers.

Appropriately enough, the new consistent-histories algorithm relies on a quantum computer to overcome the computational explosion and gauge how close to classical a quantum system is behaving. Unlike conventional computers that manipulate data made up of 1s and 0s, quantum computers store and manipulate data as quantum combinations of numbers. Similar to how an atom exists as a quantum cloud rather than at a single point, data in a quantum computer is not a single number but a superposition of many numbers.

While quantum computers powerful enough to solve meaningful problems dont exist just yet, it has been theoretically shown that they can achieve remarkable calculations, performing, in principle, exponentially faster than conventional computers. Using the consistent-histories algorithm, quantum computers have the potential to tame the difficulties of studying the quantum-to-classical transition precisely because they operate under the same rules that govern atoms and other quantum entitiesan elegant potential solution to a problem that has vexed physicists for decades.

View post:

Using Quantum Computers to Test the Fundamentals of Physics - Scientific American

Scientists at Google on Wednesday declared, via a paper in the journal Nature, that theyd done something extraordinary. In building a quantum computer that solved an incredibly hard problem in 200 seconds a problem the worlds fastest supercomputer would take 10,000 years to solve theyd achieved quantum supremacy. That is: Googles quantum computer did something that no conventional computer could reasonably do.

Computer scientists have seen quantum supremacy the moment when a quantum computer could perform an action a conventional computer couldnt as an elusive, important milestone for their field. There are many research groups working on quantum computers and applications, but it appears Google has beaten its rivals to this milestone.

According to John Preskill, the Caltech particle physicist who coined the term quantum supremacy, Googles quantum computer is something new in the exploration of nature. These systems are doing things that are unprecedented.

Of note: Some researchers at IBM contest the supremacy claim, saying that a traditional supercomputer could solve the problem in 2.5 days, not 10,000 years. Still, 200 seconds is a lot quicker than 2.5 days. If the quantum computer isnt supreme, its still extremely impressive because its so small and so efficient. They got one little chip in the quantum computer and the supercomputer is covering a basketball court, Preskill says.

It sounds all very gee-whiz. And some scientists think these computers will one day lead to discoveries of new drugs and possibly whole new fields of chemistry. Others fear theyll be used one day to crack the toughest security protocols.

But if youve never heard of a quantum computer or know what it does or what its used for, youre not alone. So lets break it down.

Before we discuss what a quantum computer is, its helpful to think about what a traditional computer is.

Traditional computers utilize the flow of electricity and can be turned on or off at switches inside circuits. Whether a switch is on or off generates the ones and zeros that underlie all computer code. This is what Alan Turing discovered in his pioneering work: Simple rules for turning those switches on and off can be used to solve any mathematical problem. These zeros and ones are called bits, and they are the smallest bit of information a computer stores.

To recap: Traditional computers use the physics of electricity, namely the fact that its flow can be turned on and off at switches, to run everything.

Quantum computers, on the other hand, are not built upon using the flow of electricity. They rely instead on the physical properties of electrons, photons, and other tiny bits of matter that are subject to the laws of quantum mechanics.

These bits of matter can do a lot more than just be turned on and off. Actually, on and off arent really words that make sense in quantum physics.

This kind of tiny matter is best described in states called amplitudes (like waves, since the tiniest bits of matter can act as both particles and waves). A particle can have two different amplitudes at the same time a state called superposition. They can also be entangled, meaning a change in one particle instantly changes another. The amplitudes of particles can also cancel one another out like opposing waves in water would. Also, the smallest particles in nature dont really exist in a point in space but they exist as a probability of existing.

For a great video explainer on quantum mechanics, check out this video by physicist Dominic Walliman.

Its all weird stuff that defies normal logic! Yet, there is a logic to it. Out of this chaotic mess of entanglement, superposition, and interference, our stable world arises.

Quantum mechanics are the rules that make reality, says Scott Aaronson, a theoretical computer scientist who studies quantum computing at the University of Texas Austin. Take an electron, he says. According to classical physics (think Newtons laws of motion), electrons should spiral into the center of atoms, rendering them useless. What quantum mechanics ultimately says is there are all these pathways where the electron can spiral into the nucleus, but they all cancel each other out.

Its hard to think about, no doubt. Its staggering what were talking about, Aaronson says. Its like the electron itself is a computer, sorting through all the possible paths it can take before finding the right ones. In a sense, the electron has solved the problem of its own existence.

Amazingly, what quantum computer engineers are doing is tapping into the chaotic logic of the quantum world to solve problems. Like a normal computer with its switches to control the flow of electricity, they build hardware to influence quantum states. (A part of the research into quantum computing is figuring out what the optimal hardware should be.) Theyre trying to choreograph quantum interactions in a way so the wrong answers to big problems get canceled out.

In a normal computer, a bit can be in two states on or off. Zero or one. But a qubit a.k.a. a quantum bit can be in many states at once. That means a single qubit can contain exponentially more information than a normal bit.

Thats a bit like having four regular computers running side by side, Cosmos magazine explains. If you add more bits to a regular computer, it can still only deal with one state at a time. But as you add qubits, the power of your quantum computer grows exponentially.

What it boils down to is that a quantum computer can crunch through some enormous problems really quickly. For instance, a lot of cybersecurity depends on computers multiplying huge prime numbers. Its really really hard for traditional computers to reverse this process, to find the prime numbers that resulted in the bigger number and crack the encryption. But quantum computers could. In a quantum computing world, we may need even stronger security protections, perhaps even those derived from quantum mechanics itself.

Scientists hope quantum computers may lead to better, quicker ways to solve optimization problems. When you have many different choices in front of you, how do you choose the ideal path? These types of questions strain traditional computers but could, potentially, be a breeze for quantum computers, which could sort through all the possible parts at once. A traditional computer has to try out each path one at a time. Though, were not going to be able to run applications like that for a while because the hardware just isnt advanced enough, Preskill adds.

Quantum computers are hard to build, are prone to generating errors, and their components are often unstable. Right now, Preskill says, what Google has shown is a proof of concept: that quantum computers can solve problems in a way traditional computers cant. Its machine runs 54 qubits. But this is a tiny fraction of the one million qubits that could be needed for a general-purpose machine, a news article at Nature states.

Quantum computers dont really do anything practical yet. The test problem Google ran for their paper was and this is a simplification to see if a random number generator was truly random.

Theyre validating that their hardware is doing what they think its supposed to be doing, Preskill says, checking that with the quantum computer they can perform the computation with many fewer steps and much faster than a classical computer.

Perhaps most of the more immediate uses would just be to use quantum computers to simulate the frenzied world of quantum mechanics and better understand it.

We can use a quantum computer as a general simulator of nature on the microscopic scale, Aaronson says, and use it to predict what a protein will do, help design a drug that will bind to a receptor in the right way, and help design new chemical reactions ... design better batteries. You would only need one or two successes to make this whole thing worthwhile.

Read more from the original source:

Google claims it reached quantum supremacy. What the heck does that mean? - Vox.com