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Category: physics – Page 193

Stephen Hawking thought an asteroid impact posed the greatest threat to life on Earth. Thanks to Kiwico for sponsoring this video. For 50% off your first month of any crate, go to https://kiwico.com/veritasium50
For other potential world ending catastrophes, check out Domain of Science: https://ve42.co/DoS

Special thanks to:
Prof. Dave Jewitt from UCLA Earth, Planetary, and Space Sciences.
Prof. Mark Boslough from Sandia National Labs.
Scott Manley: https://www.youtube.com/user/szyzyg.
Ryan Wyatt at Morrison Planetarium.
Prof. Amy Mainzer.
Alexandr Ivanov for the opening shot of Chelyabinsk Meteor.

Maps of Asteroid Impacts —https://ve42.co/Map.

Time passing animation from Universe Sandbox — http://universesandbox.com/

Continue reading “These are the asteroids to worry about” | >

Topological insulators have notable manifestations of electronic properties. The helicity-dependent photocurrents in such devices are underpinned by spin momentum-locking of surface Dirac electrons that are weak and easily overshadowed by bulk contributions. In a new report now published on Science Advances, X. Sun and a research team in photonic technologies, physics and photonic metamaterials in Singapore and the U.K. showed how the chiral response of materials could be enhanced via nanostructuring. The tight confinement of electromagnetic fields in the resonant nanostructures enhanced the photoexcitation of spin-polarized surface states of a topological insulator to allow an 11-fold increase of the circular photogalvanic effect and a previously unobserved photocurrent dichroism at room temperature. Using this method, Sun et al. controlled the spin transport in topological materials via structural design, a hitherto unrecognized ability of metamaterials. The work bridges the gap between nanophotonics and spin electronics to provide opportunities to develop polarization-sensitive photodetectors.

Chirality

Chirality is a ubiquitous and fascinating natural phenomenon in nature, describing the difference of an object from its mirror image. The process manifests in a variety of scales and forms from galaxies to nanotubes and from organic molecules to inorganic compounds. Chirality can be detected at the atomic and molecular level in fundamental sciences, including chemistry, biology and crystallography, as well as in practice, such as in the food and pharmaceutical industry. To detect chirality, scientists can use interactions with electromagnetic fields, although the process can be hindered by a large mismatch between the wavelength of light and the size of most molecules at nanoscale dimensions. Designer metamaterials with structural features comparable to the wavelength of light can provide an independent approach to devise optical properties on demand to enhance the light-matter interaction to create and enhance the optical chirality of metamaterials. In this work, Sun et al.

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O,.o arc reactor.

The Plasma Science and Fusion Center (PSFC) seeks to provide research and educational opportunities for expanding the scientific understanding of the physics of plasmas, and to use that knowledge to develop both fusion power and non-fusion applications.

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Using intuition, educated guesswork and computer simulations, condensed matter physicists have become better at figuring out which quasiparticles are theoretically possible. Meanwhile in the lab, as physicists push novel materials to new extremes, the quasiparticle zoo has grown quickly and become more and more exotic. “It really is a towering intellectual achievement,” said Natelson.

Recent discoveries include pi-tons, immovable fractons and warped wrinklons. “We now think about quasiparticles with properties that we never really dreamt of before,” said Steve Simon, a theoretical condensed matter physicist at the University of Oxford.

Here are a few of the most curious and potentially useful quasiparticles.

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A team of theoretical physicists working with Microsoft today published an amazing pre-print research paper describing the universe as a self-learning system of evolutionary laws.

In other words: We live inside a computer that learns.

The big idea: Bostrom’s Simulation Argument has been a hot topic in science circles lately. We published “What if you’re living in a simulation, but there’s no computer” recently to posit a different theory, but Microsoft’s pulled a cosmic “hold my beer” with this paper.

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Nature’s strongest material now has some stiff competition. For the first time, researchers have hard evidence that human-made hexagonal diamonds are stiffer than the common cubic diamonds found in nature and often used in jewelry.

Named for their six-sided , hexagonal diamonds have been found at some meteorite impact sites, and others have been made briefly in labs, but these were either too small or had too short of an existence to be measured.

Now scientists at Washington State University’s Institute for Shock Physics created hexagonal diamonds large enough to measure their stiffness using . Their findings are detailed in a recent paper in Physical Review B.

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The center of the Milky Way is mysteriously glowing.

Sure, there’s a whole bunch of stars there, along with a black hole 4 million times the mass of the Sun — but subtract the light from all that, and we’re still left with this mysterious excess gamma radiation that suffuses the region.

It’s called the Galactic Center GeV Excess (GCE), and it’s puzzled scientists since its discovery by physicists Lisa Goodenough and Dan Hooper in 2009. In data from NASA’s Fermi telescope, they found excess gamma radiation — some of the most energetic light in the Universe — and we haven’t been able to directly detect whatever is causing it.

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