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Category: quantum physics – Page 495

►Is faster-than-light (FTL) travel possible? In most discussions of this, we get hung up on the physics of particular ideas, such as wormholes or warp drives. But today, we take a more zoomed out approach that addresses all FTL propulsion — as well as FTL messaging. Because it turns out that they all allow for time travel. Join us today as we explore why this is so and the profound consequences that ensue. Special thanks to Prof Matt.

Written & presented by Prof David Kipping. Special thanks to Prof Matt Buckley for fact checking and his great blog article that inspired this video (http://www.physicsmatt.com/blog/2016/8/25/why-ftl-implies-time-travel)

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::References::
► Alcubierre, M., 1994, “The warp drive: hyper-fast travel within general relativity”, Classical and Quantum Gravity, 11 L73: https://arxiv.org/abs/gr-qc/0009013
► Pfenning, M. & Ford, L., 1997, “The unphysical nature of Warp Drive”, Classical and Quantum Gravity, 14, 1743: https://arxiv.org/abs/gr-qc/9702026
► Finazzi, S., Liberati, S., Barceló, C., 2009, “Semiclassical instability of dynamical warp drives”, Physical Review D., 79, 124017: https://arxiv.org/abs/0904.0141
► McMonigal, B., Lewis, G., O’Byrne, P., 2012, “Alcubierre warp drive: On the matter of matter”, Physical Review D., 85, 064024: https://arxiv.org/abs/1202.5708
► Everett, A., 1996, “Warp drive and causality”, Physical Review D, 53, 7365: https://journals.aps.org/prd/abstract/10.1103/PhysRevD.53.

::Music::

Continue reading “Why Going Faster-Than-Light Leads to Time Paradoxes” | >

A new method of identifying gravitational wave signals using quantum computing could provide a valuable new tool for future astrophysicists.

A team from the University of Glasgow’s School of Physics & Astronomy have developed a to drastically cut down the time it takes to match gravitational wave signals against a vast databank of templates.

This process, known as matched filtering, is part of the methodology that underpins some of the gravitational wave signal discoveries from detectors like the Laser Interferometer Gravitational Observatory (LIGO) in America and Virgo in Italy.

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In the new field of quantum computing, magnetic interactions could play a role in relaying quantum information.

In new research, Argonne scientists achieved efficient quantum coupling between two distant magnetic devices, which which may be useful for creating new quantum information technology devices — https://bit.ly/3uk88Q3

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What do quantum computers have to do with smog-filled London streets, flying submarines, waistcoats, petticoats, Sherlock Holmesian mysteries, and brass goggles?

A whole lot, according to Nicole Yunger Halpern. Last week, the joined Jacob Barandes, co-director of graduate studies for physics, to discuss her new book, “Quantum Steampunk: The Physics of Yesterday’s Tomorrow.” In it, Yunger Halpern dissects a new branch of science—quantum thermodynamics, or quantum steampunk as she calls it—by fusing steampunk fiction with nonfiction and Victorian-era thermodynamics (the heat and energy that gets pumping) with . Yunger Halpern presents a whimsical lens through which readers can watch a “scientific revolution that’s happening in real time,” Barandes said, exploring mysteries even Holmes couldn’t hope to solve, such as why time flows in only one direction.

“This fusion of old and new creates a wonderful sense of nostalgia and adventure, romance and exploration,” Yunger Halpern said during a virtual Harvard Science Book Talk presented by the University’s Division of Science, Cabot Science Library, and Harvard Book Store. In steampunk, she continued, “fans dress up in costumes full of top hats and goggles and gears and gather at conventions. What they dream, I have the immense privilege of having the opportunity to live.”

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A new theoretical paper has tackled the phenomenon of quantum decoherence.

A new theoretical paper has tackled the phenomenon of quantum decoherence, the process by which objects slip out of the quantum world and start behaving classically. The paper approaches this in a new way by applying an effect of general relativity to decoherence. The paper claims that gravity is the key to the disparity between the weird quantum world and the everyday, familiar world of human-sized objects in which we live.

Schrödinger’s cat is an example of a quantum system which might decohere due to time dilation — and myriad other interactions.

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Quantum information theory: Quantum complexity grows linearly for an exponentially long time.

Physicists know about the huge chasm between quantum physics and the theory of gravity. However, in recent decades, theoretical physics has provided some plausible conjecture to bridge this gap and to describe the behavior of complex quantum many-body systems, for example black holes and wormholes in the universe. Now, a theory group at Freie Universität Berlin and HZB, together with Harvard University, USA, has proven a mathematical conjecture about the behavior of complexity in such systems, increasing the viability of this bridge. The work is published in Nature Physics.

“We have found a surprisingly simple solution to an important problem in physics,” says Prof. Jens Eisert, a theoretical physicist at Freie Universität Berlin and HZB. “Our results provide a solid basis for understanding the physical properties of chaotic quantum systems, from black holes to complex many-body systems,” Eisert adds.

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When a bubble pops in a liquid, it can produce a flash of light, which we now know is thanks to quantum mechanics.

Sonoluminescence is a phenomenon in which small bubbles, produced and fixed in place by an ultrasound wave in a liquid, collapse and make particles of light, or photons. Physicists have known about this process for decades, but the mechanisms behind it weren’t fully known.

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The information paradox may finally be resolved with the help of the holographic theory – but this time on a fractal scale.

Ever since Hawking predicted the thermal emission of black holes and their subsequent evaporation, the question arose as to where this information goes. In the context of the Copenhagen interpretation of quantum mechanics – which states that the information about a system is entirely encoded in its wave function – information is always conserved. Thus, any loss in information, like that predicted by Hawking and his evaporating black holes, would violate quantum theory. This problem is known as the information paradox.

To resolve this paradox, physicists have been actively looking for a mechanism to explain how the information of the infalling particles re-emerges in the outgoing radiation. To begin, they need to determine the entropy of the Hawking radiation.

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Researchers uncovered new information about an important subatomic particle and a long-theorized fifth force of nature.

A group of researchers have used a groundbreaking new technique to reveal previously unrecognized properties of technologically crucial silicon crystals and uncovered new information about an important subatomic particle and a long-theorized fifth force of nature.

The research was an international collaboration conducted at the National Institute of Standards and Technology (NIST). Dmitry Pushin, a member of the University of Waterloo’s Institute for Quantum Computing and a faculty member in Waterloo’s Department of Physics and Astronomy, was the only Canadian researcher involved in the study. Pushin was interested in producing high-quality quantum sensors out of perfect crystals.

By aiming subatomic particles known as neutrons at silicon crystals and monitoring the outcome with exquisite sensitivity, researchers were able to obtain three extraordinary results: the first measurement of a key neutron property in 20 years using a unique method; the highest-precision measurements of the effects of heat-related vibrations in a silicon crystal; and limits on the strength of a possible “fifth force” beyond standard physics theories.

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