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Category: particle physics – Page 283

The early 20th century saw the advent of quantum mechanics to describe the properties of small particles, such as electrons or atoms. Schrödinger’s equation in quantum mechanics can successfully predict the electronic structure of atoms or molecules. However, the “duality” of matter, referring to the dual “particle” and “wave” nature of electrons, remained a controversial issue. Physicists use a complex wavefunction to represent the wave nature of an electron.

“Complex” numbers are those that have both “real” and “imaginary” parts—the ratio of which is referred to as the “phase.” However, all directly measurable quantities must be “real”. This leads to the following challenge: when the electron hits a detector, the “complex” phase information of the disappears, leaving only the square of the amplitude of the wavefunction (a “real” value) to be recorded. This means that electrons are detected only as particles, which makes it difficult to explain their dual properties in atoms.

The ensuing century witnessed a new, evolving era of physics, namely, physics. The attosecond is a very short time scale, a billionth of a billionth of a second. “Attosecond physics opens a way to measure the phase of electrons. Achieving attosecond time-resolution, electron dynamics can be observed while freezing ,” explains Professor Hiromichi Niikura from the Department of Applied Physics, Waseda University, Japan, who, along with Professor D. M. Villeneuve—a principal research scientist at the Joint Attosecond Science Laboratory, National Research Council, and adjunct professor at University of Ottawa—pioneered the field of attosecond physics.

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Researchers have observed steric effects—the interactions of molecules depending on their spatial orientation (not just between their electrons involved in bonding)—in a chemical reaction involving non-polar molecules for the first time. The breakthrough opens the door to an entirely new way to control the products of chemical reactions.

A paper describing the research team’s findings was published in the journal Science on Jan. 12.

One of the central goals of chemistry is to develop new methods of controlling chemical reactions. For the most part, control of chemical reactions involves understanding of the interactions between the electrons of different atoms. These “electronic” effects govern many of the properties and behavior of chemicals and the changes they undergo during reactions.

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Of course, all stars are hot compared with anything we’re used to here on Earth. But while the Sun’s surface chills at a steady 6,000 degrees Kelvin, these stars’ extreme temperatures range from 100,000 to 180,000 degrees.

These are “stars which are a little bit outside the canonical evolution,” Klaus Werner of the University of Tuebingen’s Kepler Centre for Astro and Particle Physics, a co-author of the paper, tells Inverse. “These stars are strange.”

Even among the ultra-hot white dwarfs known by the designation PG1159, the selection that cropped up in this survey lack the helium normally found in their atmosphere: instead, they’ve burned it all away, fusing it into a solar atmosphere of pure carbon and oxygen.

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Silently churning away at the heart of every atom in the Universe is a swirling wind of particles that physics yearns to understand.

No probe, no microscope, and no X-ray machine can hope to make sense of the chaotic blur of quantum cogs whirring inside an atom, leaving physicists to theorize the best they can based on the debris of high-speed collisions inside particle colliders.

Researchers now have a new tool that is already providing them with a small glimpse into the protons and neutrons that form the nuclei of atoms, one based on the entanglement of particles produced as gold atoms brush past each other at speed.

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The world of the very, very small is a wonderland of strangeness. Molecules, atoms, and their constituent particles did not readily reveal their secrets to the scientists that wrestled with the physics of atoms in the early 20th century. Drama, frustration, anger, puzzlement, and nervous breakdowns abounded, and it is hard for us now, a full century later, to understand what was at stake. What happened was a continuous process of worldview demolition. You might have to give up believing everything you thought to be true about something. In the case of the quantum physics pioneers, that meant changing their understanding about the rules that dictate how matter behaves.

In 1913, Bohr devised a model for the atom that looked somewhat like a solar system in miniature. Electrons moved around the atomic nucleus in circular orbits. Bohr added a few twists to his model — twists that gave them a set of weird and mysterious properties. The twists were necessary for Bohr’s model to have explanatory power — that is, for it to be able to describe the results of experimental measurements. For example, electrons’ orbits were fixed like railroad tracks around the nucleus. The electron could not be in between orbits, otherwise it could fall into the nucleus. Once it got to the lowest rung in the orbital ladder, an electron stayed there unless it jumped to a higher orbit.

Clarity about why this happened started to come with de Broglie’s idea that electrons can be seen both as particles and waves. This wave-particle duality of light and matter was startling, and Heisenberg’s uncertainty principle gave it precision. The more precisely you localize the particle, the less precisely you know how fast it moves. Heisenberg had his own theory of quantum mechanics, a complex device to compute the possible outcomes of experiments. It was beautiful but extremely hard to calculate things with.

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In a first, physicists have now found interference between two dissimilar subatomic particles. Researchers made the observation at the Relativistic Heavy Ion Collider (RHIC), a colossal particle accelerator at Long Island’s Brookhaven National Laboratory. The finding broadens the way we understand entanglement and offers new opportunities to use it to study the subatomic world.

“With this new technique, we are able to measure the size and shape of the nucleus to about a tenth of a femtometer, a tenth of the size of an individual proton,” says James Daniel Brandenburg, a physicist at the Ohio State University and a member of RHIC’s STAR experiment, where the new phenomenon was seen. That’s 10 to 100 times more precise than previous measurements of high-energy atomic nuclei.

RHIC is designed to collide heavy ions, such as the nuclei of gold atoms. In this case, though, researchers were interested in near misses, not collisions. As the gold nuclei zing at near light speed through the collider, they create an electromagnetic field that generates photons. When two gold nuclei come close to one another but don’t collide, the photons may ping off the neighboring nuclei. These near misses used to be considered background noise, says STAR collaborator Raghav Kunnawalkam Elayavalli, a physicist at Vanderbilt University. But looking at the close-call events “opened up a whole new field of physics that initially was not accessible,” Kunnawalkam Elayavalli says.

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“Suppose you knew everything there was to know about a water molecule—the chemical formula, the bond angle, etc.,” says Joseph Thywissen, a professor in the Department of Physics and a member of the Centre for Quantum Information & Quantum Control at the University of Toronto.

“You might know everything about the molecule, but still not know there are waves on the ocean, much less how to surf them,” he says. “That’s because when you put a bunch of molecules together, they behave in a way you probably cannot anticipate.”

Thywissen is describing the concept in physics known as emergence: the relationship between the behavior and characteristics of individual particles and large numbers of those particles. He and his collaborators have taken a first step in understanding this transition from “one-to-many” particles by studying not one, not many, but two isolated, interacting particles, in this case potassium atoms.

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For the first time, scientists have performed an iconic physics experiment with a positron — the antimatter counterpart of an electron, one of the fundamental particles.

Not only did they get some truly interesting results, but this achievement could become the first step towards potentially revolutionary discoveries.

The experiment — an antimatter version of the famous double-slit setup — was carried out by researchers from Switzerland and Italy in order to lay the groundwork for a novel line of super-sensitive experiments that might help solve a mystery concerning the Universe’s two domains of matter.

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This week our guest is Meghan O’Gieblyn, who has written regularly for entities such as Wired, The New York Times, and The Guardian, in addition to authoring books such as Interior States and her latest book: God, Human, Animal, Machine: Technology, Metaphor, and the Search for Meaning.

Interestingly, much of Meghan’s work pulls on her experience losing her faith in religion while simultaneously being drawn into transhumanism from reading the Age of Spiritual Machines by Singularity’s very own Ray Kurzweil. This exploration of Meghan’s background and her latest book takes us on a journey through the ways in which technology and spirituality have historically woven together, the current ways in which they are conflicting, and the future philosophical questions we’re going to be forced to reconcile. For those of you interested in this subject, I highly recommend going and listening to episode 52 with Micah Redding, which lays a lot of the foundation that we build on her in this episode.

Find out more about Meghan through her website meghanogieblyn.com, or find her book on Amazon.

Host: steven parton — linkedin / twitter.

Music by: Amine el Filali.

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