Physicists can’t agree.
Physicists define black holes according to their field’s needs.
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Category: physics – Page 258
An invisible force is having an effect on our Universe. We can’t see it, and we can’t detect it — but we can observe how it interacts gravitationally with the things we can see and detect, such as light.
Now an international team of astronomers has used one of the world’s most powerful telescopes to analyse that effect across 10 million galaxies in the context of Einstein’s general relativity. The result? The most comprehensive map of dark matter across the history of the Universe to date.
It has yet to complete peer-review, but the map has suggested something unexpected — that dark matter structures might be evolving more slowly than previously predicted.
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In a finding that runs counter to a common assumption in physics, researchers at the University of Michigan ran a light emitting diode (LED) with electrodes reversed in order to cool another device mere nanometers away.
The approach could lead to new solid-state cooling technology for future microprocessors, which will have so many transistors packed into a small space that current methods can’t remove heat quickly enough.
“We have demonstrated a second method for using photons to cool devices,” said Pramod Reddy, who co-led the work with Edgar Meyhofer, both professors of mechanical engineering.
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What they found was surprising. The new map, published on the preprint server arXiv, suggests that the huge structure of dark matter in the universe formed more slowly that previously believed — results that “appear to challenge current understanding of the fundamental laws of physics,” according to the press release.
Road Ahead
But before physicists throw out the rulebook, Hikage cautioned that the new map needs to be corroborated.
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Why does time seem to move forward? It’s a riddle that’s puzzled physicists for well over a century, and they’ve come up with numerous theories to explain time’s arrow. The latest, though, suggests that while time moves forward in our universe, it may run backwards in another, mirror universe that was created on the “other side” of the Big Bang.
Two leading theories propose to explain the direction of time by way of the relatively uniform conditions of the Big Bang. At the very start, what is now the universe was homogeneously hot, so much so that matter didn’t really exist. It was all just a superheated soup. But as the universe expanded and cooled, stars, galaxies, planets, and other celestial bodies formed, birthing the universe’s irregular structure and raising its entropy.
One theory, proposed in 2004 by Sean Carroll, now a professor at Caltech, and Jennifer Chen, then his graduate student, says that time moves forward because of the contrast in entropy between then and now, with an emphasis on the fact that the future universe will so much more disordered than the past. That movement toward high entropy gives time its direction.
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In the early 1990s, I was lucky enough to get some time on a 60 MeV linear accelerator as part of an undergraduate lab course. Having had this experience, I can feel for the scientists at CERN who have had to make do with their current 13 TeV accelerator, which only manages energies some 200,000 times larger. So, I read with great interest when they announced the publication of the initial design concept for the Future Circular Collider (FCC), which promises collisions nearly an order of magnitude more energetic. The plan, which has been in the works since 2014, includes three proposals for accelerators which would succeed CERN’s current big iron, the LHC.
Want to know what’s on the horizon in high-energy physics?
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There’s a renewed interest right now in Earth’s magnetic poles – specifically, whether or not they’re about to flip, and what may happen. The consequences of this seemingly rapid geomagnetic backflip may sound a little ominous, but don’t worry: we’re not sure when the next reversal will happen, and even when it does, the risks aren’t likely to be as scary as you may think.
Let’s start with the basics.
As Earth’s liquid, iron-rich outer core gradually cools, it sloshes around through colossal convection currents, which are also somewhat warped by Earth’s own rotation. Thanks to a quirk of physics known as the dynamo theory, this generates a powerful magnetic field, with a north and south end.
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Many of today’s methods of purifying water rely on filters and chemicals that need regular replenishing or maintenance. Millions of people, however, live in areas with limited access to such materials, leading the research community to explore new options of purifying water in using plasmas. Many plasma-based approaches are expensive, but a new class of plasma devices may change that.
Researchers at the University of Alabama in Huntsville have been studying a new type of plasma generator for water purification. The new generator pulses voltage signals to ionize gas at atmospheric pressure and produce many useful byproducts, including hydroxyl radicals, which cause a cascade of reactions that lead to purer water samples.
“We’re finding ways to speed up the purification process,” said Ryan Gott, a doctoral candidate in aerospace engineering at UAH who will present the research next week at the American Physical Society 71st Annual Gaseous Electronics Conference and the 60th Annual meeting of the APS Division of Plasma Physics, which will take place Nov. 5–9 at the Oregon Convention Center in Portland.
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Researchers at the University of South Carolina in Columbia have demonstrated an experimental plasma device capable of cleaning gas samples of D4, one of the most common siloxanes. Drawing on a technique for creating plasma called dielectric barrier discharge, the group was able to significantly reduce the amount of D4 samples after treating it with a helium-based plasma.
The findings point to a new potential solution for accommodating landfill gas rich in siloxanes. They will be presented at the American Physical Society 71st Annual Gaseous Electronics Conference and 60th Annual meeting of the APS Division of Plasma Physics, which takes place Nov. 5–9 at the Oregon Convention Center in Portland.
“This is the first time dielectric barrier discharge has been used to remove volatile organic silicate compounds,” said Malik Tahiyat, one of the researchers involved with the study. “In our case, there’s no wait for removing it or material that has to be thrown out after a certain amount of time.”
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