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Category: cosmology – Page 285

CREATING ARTIFICIAL SKIES IN UNDERGROUND HABITATS ON MARS & MERCURY. This will be an interesting subject for much deliberation in the future: how to best create artificial skies in sealed habitats. Metamaterial vantablack is a surface so perfectly dark that if you stood in a room where the ceiling, walls and floor were covered with it, you would feel like you were floating in black space. Disneyland must get off its butt and create a big room like this. Now a new paint (not quite the opposite of vantablack as it claims) has been invented, which will reflect back nearly 100% of light hitting it, an interesting way to augment existing lighting in a building by painting the ceiling with the stuff.

And here is something which I told you before: if the human eye stares at a totally uniform color, with no discernable features it doesn’t know where to focus, and psychologically can see this as a kind of “sky.” Since there is nothing to focus on, the eye assumes it is the far away sky and focusses to infinity or goes into its least-energetic focusing mode, as in looking at a blank sky.

View a large computer screen with a totally uniform color, through a tube which blocks the edge of the screen from view. You already see this effect with this small experiment.

New paint reflects nearly all light hitting it, can help cool down space probes:

Continue reading “This Whiter-Than-White Paint Is Like the Opposite of Vantablack” | >

Crews working on the largest U.S. experiment designed to directly detect dark matter completed a major milestone last month, and are now turning their sights toward startup after experiencing some delays due to global pandemic precautions.

U.S. Department of Energy officials on Sept. 21 formally signed off on project completion for LUX-ZEPLIN, or LZ: an ultrasensitive experiment that will use 10 metric tons of liquid xenon to hunt for signals of interactions with theorized dark matter particles called WIMPs, or weakly interacting massive particles. DOE’s project completion milestone is called Critical Decision 4, or CD-4.

Dark matter makes up an estimated 85 percent of all matter in the universe. We know it’s there because of its observed gravitational effects on normal matter, but we don’t yet know what it is. LZ is designed to detect the two flashes of light that occur if a WIMP interacts with the nucleus of a xenon atom.

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Optical clocks are so accurate that it would take an estimated 20 billion years—longer than the age of the universe—to lose or gain a second. Now, researchers in the U.S. led by Jun Ye’s group at the National Institute of Standards and Technology and the University of Colorado have exploited the precision and accuracy of their optical clock and the unprecedented stability of their crystalline silicon optical cavity to tighten the constraints on any possible coupling between particles and fields in the standard model of physics and the so-far elusive components of dark matter.

The existence of dark matter is indirectly evident from gravitational effects at galactic and cosmological scales, but beyond that, little is known of its nature. One of the effects that falls out of theoretical analysis of dark matter coupling to particles in the standard model of physics is a resulting oscillation in . Ye and collaborators figured that if their world-class metrology equipment could not detect these oscillations, then this apparently null result would be useful confirmation that the strength of dark matter interactions with particles in the standard model of physics must be even lower than dictated by the constraints so far on record.

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A recent study from the University of Melbourne proposes a new theory for the origin of dark matter, helping experimentalists in Australia and abroad in the search for the mysterious new matter.

The work has been published in Physical Review Letters and describes how expanding bubbles in the early universe may be the key to understanding dark matter.

“Our proposed mechanism suggests that the dark matter abundance may have been determined in a cosmological phase transition,” said Dr. Michael Baker, a postdoctoral research fellow at the University of Melbourne and one of the authors.

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Look into the night sky and you’ll glimpse the stars from hundreds of billions of galaxies. Some galaxies are swirling blue disks like our own Milky Way, others are red spheres or misshapen, clumpy messes or something in between. Why the different configurations? It turns out that a galaxy’s shape tells us something about the events in that galaxy’s ultra-long life.

At the very basic level there are two classifications for galaxy shapes: disk and elliptical. A disk galaxy, also called a spiral galaxy, is shaped like a fried egg, said Cameron Hummels, theoretical astrophysicist at Caltech. These galaxies have a more spherical center, like the yolk, surrounded by a disk of gas and stars — the egg white. The Milky Way and our nearest galaxy neighbor Andromeda fall into this category.

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Circa 2010

Until the LHC finally gets up to full speed, Brookhaven National Lab’s Relativistic Heavy Ion Collider (RHIC) remains the world’s most powerful heavy ion smasher. And on Monday, they showed off some of that power by announcing that a recent collision resulted in the hottest matter ever recorded. Coming in at a scorching 7.2 trillion degrees Fahrenheit, the plasma not only recreated the environment of the Big Bang, but might have also resulted in the temporary formation of a bubble within which some normal laws of physics did not apply.

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Black holes are perhaps the most mysterious objects in nature. They warp space and time in extreme ways and contain a mathematical impossibility, a singularity – an infinitely hot and dense object within. But if black holes exist and are truly black, how exactly would we ever be able to make an observation?

This morning the Nobel Committee announced that the 2020 Nobel Prize in physics will be awarded to three scientists – Sir Roger Penrose, Reinhard Genzel and Andrea Ghez – who helped discover the answers to such profound questions. Andrea Ghez is only the fourth woman to win the Nobel Prize in physics.

Robert Penrose is a theoretical physicist who works on black holes, and his work has influenced not just me but my entire generation through his series of popular books that are loaded with his exquisite hand-drawn illustrations of deep physical concepts.

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