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Category: particle physics – Page 352

Experiments Deliver Superposition Of Photon Going Forward And Backward In Time

Two different groups have tested a seemingly counter-intuitive property of the quantum world: That it’s possible to put a photon, a particle of light, in a superposition of states going forward and backward in time. This is not time travel and won’t lead to communicating with the past – but it is an intriguing demonstration of how time can be thought to work at a quantum level.

Unless you have a TARDIS or a DeLorean, time only flows in one direction (forward) for us. This annoying little fact that protects us from all sorts of paradoxes is called the arrow of time. It is believed to be related to the concept of entropy (which always increases in an isolated system like the universe) but it doesn’t seem to be as fundamental at the quantum level.

Instead, something that appears to be fundamental is the so-called CPT symmetry (charge, parity, and time reversal symmetry). This holds for all physical phenomena, and if a combination of two of them is violated (such as famously the CP violations) there ought to be a violation in time symmetry as well.

Four common misconceptions about quantum physics

Quantum mechanics, the theory which rules the microworld of atoms and particles, certainly has the X factor. Unlike many other areas of physics, it is bizarre and counter-intuitive, which makes it dazzling and intriguing. When the 2022 Nobel prize in physics was awarded to Alain Aspect, John Clauser and Anton Zeilinger for research shedding light on quantum mechanics, it sparked excitement and discussion.

But debates about —be they on chat forums, in the media or in science fiction—can often get muddled thanks to a number of persistent myths and misconceptions. Here are four.

Gamma Ray Generation Using High-Powered Lasers

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This article focuses on the concept of gamma rays, their sources and emitters. It then focuses on the presence of gamma rays in the cosmos and how they are generated. Finally, it talks about joint research between facilities in the US and Czech Republic and how they would benefit the gamma-ray generation process.

Image Credit: sakkmesterke/Shutterstock.com

What are Gamma Rays?

In simple terms, gamma rays can be defined as packets of electromagnetic energies which are emitted after radioactive decay. In the electromagnetic spectrum, gamma rays are deemed to be the most radioactive rays of all. Gamma rays can often be confused with X rays, but the key difference is that an excited nucleus produces gamma rays in an atom instead of an excited electron.

Matter–antimatter gigaelectron volt gamma ray laser rocket propulsion

face_with_colon_three circa 2012.

It is shown that the idea of a photon rocket through the complete annihilation of matter with antimatter, first proposed by Sänger, is not a utopian scheme as it is widely believed. Its feasibility appears to be possible by the radiative collapse of a relativistic high current pinch discharge in a hydrogen–antihydrogen ambiplasma down to a radius determined by Heisenberg’s uncertainty principle. Through this collapse to ultrahigh densities the proton–antiproton pairs in the center of the pinch can become the upper gigaelectron volt laser level for the transition into a coherent gamma ray beam by proton–antiproton annihilation, with the magnetic field of the collapsed pinch discharge absorbing the recoil momentum of the beam and transmitting it by the Moessbauer effect to the spacecraft. The gamma ray laser beam is launched as a photon avalanche from one end of the pinch discharge channel. Because of the enormous technical problems to produce and store large amounts of anti-matter, such a propulsion concept may find its first realization in small unmanned space probes to explore nearby solar systems. The laboratory demonstration of a gigaelectron volt gamma ray laser by comparison requiring small amounts of anti-matter may be much closer.

An early universe analog built in a lab in Germany

A team of researchers at Universität Heidelberg has built an early universe analog in their laboratory using chilled potassium atoms. In their paper published in the journal Nature, the group describes their simulator and how it might be used. Silke Weinfurtner, with the University of Nottingham, has published a News & Views piece in the same journal issue outlining the work done by the team in Germany.

Understanding what occurred during the first few moments after the Big Bang is difficult due to the lack of evidence left behind. That leaves astrophysicists with nothing but theory to describe what might have happened. To give credence to their theories, scientists have built models that theoretically represent the conditions being described. In this new effort, the researchers used a new approach to build a in their laboratory to simulate conditions just after the Big Bang.

Beginning with the theory that that the Big Bang gave rise to an , the researchers sought to create what they describe as a “quantum field simulator.” Since most theories suggest it was likely that the was very cold, near absolute zero, the researchers created an environment that was very cold. They then added potassium atoms to represent the universe they were trying to simulate.

Scientists use a quantum state of matter to simulate the early universe’s expansion

The scientists said their spacetime simulation “agrees very well with theory.”

A team of physicists used a “quantum field simulator” to simulate a tiny expanding universe made out of ultracold atoms, a report from VICE

Simulating spacetime.

Pixelparticle/iStock.

The scientists conducted the experiment to simulate the early rapid expansion of the universe following the Big Bang. Their work could lead to accurate representations of the universe in future experiments, allowing for the testing of countless models of the early evolution of the cosmos.

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