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Category: particle physics

Neutrinos may be the key to finally solving a mystery of the origins of our matter-dominated universe, and preparations for two major, billion-dollar experiments are underway to reveal the particles’ secrets. Now, a team of nuclear physicists have turned to the humble electron to provide insight for how these experiments can better prepare to capture critical information. Their research, which was carried out at the U.S. Department of Energy’s Thomas Jefferson National Accelerator Facility and recently published in Nature, reveals that major updates to neutrino models are needed for the experiments to achieve high-precision results.

Neutrinos are ubiquitous, generated in copious numbers by stars throughout our universe. Though prevalent, these shy particles rarely interact with matter, making them very difficult to study.

“There is this phenomenon of neutrinos changing from one type to another, and this phenomenon is called . It’s interesting to study this phenomenon, because it is not well understood,” said Mariana Khachatryan, a co-lead author on the study who was a graduate student at Old Dominion University in Professor and Eminent Scholar Larry Weinstein’s research group when she contributed to the research. She is now a postdoctoral research associate at Florida International University.

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Rarely does scientific software spark such sensational headlines. “One of biology’s biggest mysteries ‘largely solved’ by AI”, declared the BBC. Forbes called it “the most important achievement in AI — ever”. The buzz over the November 2020 debut of AlphaFold2, Google DeepMind’s (AI) system for predicting the 3D structure of proteins, has only intensified since the tool was made freely available in July.

The excitement relates to the software’s potential to solve one of biology’s thorniest problems — predicting the functional, folded structure of a protein molecule from its linear amino-acid sequence, right down to the position of each atom in 3D space. The underlying physicochemical rules for how proteins form their 3D structures remain too complicated for humans to parse, so this ‘protein-folding problem’ has remained unsolved for decades.

Researchers have worked out the structures of around 160,000 proteins from all kingdoms of life. They have been using experimental techniques, such as X-ray crystallography and cryo-electron microscopy (cryo-EM), and then depositing their 3D information in the Protein Data Bank. Computational biologists have made steady gains in developing software that complements these methods, and have correctly predicted the 3D shapes of some molecules from well-studied protein families.

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And that’s where physicists are getting stuck.

Zooming in to that hidden center involves virtual particles — quantum fluctuations that subtly influence each interaction’s outcome. The fleeting existence of the quark pair above, like many virtual events, is represented by a Feynman diagram with a closed “loop.” Loops confound physicists — they’re black boxes that introduce additional layers of infinite scenarios. To tally the possibilities implied by a loop, theorists must turn to a summing operation known as an integral. These integrals take on monstrous proportions in multi-loop Feynman diagrams, which come into play as researchers march down the line and fold in more complicated virtual interactions.

Physicists have algorithms to compute the probabilities of no-loop and one-loop scenarios, but many two-loop collisions bring computers to their knees. This imposes a ceiling on predictive precision — and on how well physicists can understand what quantum theory says.

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Work has potential applications in quantum computing, and introduces new way to plumb the secrets of superconductivity. MIT physicists and colleagues have demonstrated an exotic form of superconductivity in a new material the team synthesized only about a year ago. Although predicted in the 1960s.

“An important theme of our research is that new physics comes from new materials,” says Joseph Checkelsky, lead principal investigator of the work and the Mitsui Career Development Associate Professor of Physics. “Our initial report last year was of this new material. This new work reports the new physics.”

Checkelsky’s co-authors on the current paper include lead author Aravind Devarakonda PhD ’21, who is now at Columbia University. The work was a central part of Devarakonda’s thesis. Co-authors are Takehito Suzuki, a former research scientist at MIT now at Toho University in Japan; Shiang Fang, a postdoc in the MIT Department of Physics; Junbo Zhu, an MIT graduate student in physics; David Graf of the National High Magnetic Field Laboratory; Markus Kriener of the RIKEN Center for Emergent Matter Science in Japan; Liang Fu, an MIT associate professor of physics; and Efthimios Kaxiras of Harvard University.

New quantum material

Classical physics can be used to explain any number of phenomena that underlie our world — until things get exquisitely small. Subatomic particles like electrons and quarks behave differently, in ways that are still not fully understood. Enter quantum mechanics, the field that tries to explain their behavior and resulting effects.

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Scientists at the University of Birmingham have succeeded in creating an experimental model of an elusive kind of fundamental particle called a skyrmion in a beam of light.

The breakthrough provides physicists with a real system demonstrating the behavior of skyrmions, first proposed 60 years ago by a University of Birmingham mathematical physicist, Professor Tony Skyrme.

Skyrme’s idea used the structure of spheres in 4-dimensional space to guarantee the indivisible nature of a skyrmion particle in 3 dimensions. 3D particle-like skyrmions are theorized to tell us about the early origins of the Universe, or about the physics of exotic materials or cold atoms. However, despite being investigated for over 50 years, 3D skyrmions have been seen very rarely in experiments. The most current research into skyrmions focuses on 2D analogs, which shows promise for new technologies.

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Terraforming Mars is one of the great dreams of humanity. Mars has a lot going for it. Its day is about the same length as Earth’s, it has plenty of frozen water just under its surface, and it likely could be given a reasonably breathable atmosphere in time. But one of the things it lacks is a strong magnetic field. So if we want to make Mars a second Earth, we’ll have to give it an artificial one.

The reason magnetic fields are so important is that they can shield a planet from solar wind and ionizing particles. Earth’s magnetic field prevents most high-energy charged particles from reaching the surface. Instead, they are deflected from Earth, keeping us safe. The magnetic field also helps prevent solar winds from stripping Earth’s atmosphere over time. Early Mars had a thick, water-rich atmosphere, but it was gradually depleted without the protection of a strong magnetic field.

Unfortunately, we can’t just recreate Earth’s magnetic field on Mars. Our field is generated by a dynamo effect in Earth’s core, where the convection of iron alloys generates Earth’s geomagnetic field. The interior of Mars is smaller and cooler, and we can’t simply “start it up” to create a magnetic dynamo. But there are a few ways we can create an artificial magnetic field, as a recent study shows.

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Superconductivity occurs when electrons in a metal pair up and move through the material without resistance. But there may be more to the story than we thought, as scientists in Germany have now discovered that electrons can also group together into families of four, creating a new state of matter and, potentially, a new type of superconductivity.

Conductivity is a measure of how easily electrons (and therefore electricity) can move through a material. But even in materials that make good conductors, like gold, electrons will still encounter some resistance. Superconductors, however, remove all such barriers and provide zero resistance at ultracold temperatures.

The reason electrons can move through superconductors so easily is because they pair up through a quantum effect known as Cooper pairing. In doing so, they raise the minimum amount of energy it takes to interfere with the electrons – and if the material is cold enough, its atoms won’t have enough thermal energy to disturb these Cooper pairs, allowing the electrons to flow freely with no loss of energy.

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What is entanglement theory? It is a Mystery, and here is a potential solution. But its implications are so paradigm shattering that most scientists refuse to believe it. Maybe we can’t handle the truth?

Imagine you found a pair of dice such that no matter how you tossed them, they always added up to 7. Besides becoming the richest man in Vegas, what you would have there is something called an entangled pair of dice.

You could now separate these entangled dice. You could have your friend Alice take one of these to Macau, while the other one stays with you in Las Vegas. And as soon as you rolled your dice, the other one would always instantly show a number that added up to 7.

Since this happens instantly, did your dice communicate at faster than speed of light to Macau?

Scientists can create entangled photons, for example, by shining a laser on a nonlinear optical crystal. The Entanglement means that a pair of photons act like a single entity rather than two separate particles. To understand entanglement better, you first have to accept the fact that at the quantum scale, reality is fuzzy. Reality really doesn’t know what it is, until it is measured.

This is like a single dice tossed in the air that doesn’t have a distinct face until it lands. When tossed up, it is 1, 2, 3, 4, 5, and 6 all at once. Quantum particles are similar in that they do not have distinct properties until they are measured. Particles such as a photon exists in all possible states simultaneously. But when it is measured, it is in only one state. And if the photon is entangled, this measurement of one particle causes its entangled pair to simultaneously exhibit the opposite state, no matter what the distance is between them.

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Special offer for ArvinAsh viewers — Go to: https://brilliant.org/arvinash — you can sign up for free! The first 200 people will get 20% off their annual membership.

Background videos:
Fundamental forces: https://youtu.be/669QUJrF4u0
Electroweak theory: https://youtu.be/u05VK0pSc7I
Is Big Bang hidden in gravity waves: https://youtu.be/VXr1mzY2GnY
Cosmic Microwave background: https://youtu.be/XcXCrFIivyk.

Errata:
12:26 — Helium-3 has 2 protons and 1 Neutron.

Chapters:
0:00 — How many atoms are there?
1:01 — We don’t know what happened at or before t=0
3:34 — Cosmic inflation.
5:27 — What we do know.
8:29 — How protons and neutrons formed.
10:41 — How charged nucleons formed.
13:47 — How neutral atoms formed.
15:24 — How to learn more about atoms.

Summary:
Where did the first atom come from? The short answer is the big bang. In the early universe there was an immense amount of energy, The energy condensed, atoms formed. But there’s a lot more that happened, which will be explained here.

The big bang is often thought of as the theory explaining the beginning. but it’s not. We don’t know when the universe actually started, or whether it did. Our best theory of the early universe is the standard model of cosmology, We can only go back to one Planck time, about 10^−43 seconds. This is the smallest unit of time that can theoretically exist according to quantum mechanics. We don’t know what came before this.

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