In a landmark series of calculations, physicists have proved that black holes can shed information, which seems impossible by definition. The work appears to resolve a paradox that Stephen Hawking first described five decades ago.
Category: cosmology
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Cosmic Loners
The problem with the GEODE hypothesis is that the strange objects need to resemble but not act like black holes. The only way that GEODEs could expand the universe without destroying everything around them is if they were isolated in empty pockets of the cosmos. But black holes often sit smack dab in the middle of galaxies.
“This becomes a problem if you want to explain the accelerating expansion of the universe,” lead author Kevin Croker said in a press release. “If they moved like black holes, staying close to visible matter, galaxies like our own Milky Way would have been disrupted.”
The catalogue also provides information on how the black holes spin, which holds the key to understanding how the objects came to orbit each other before they merged. It shows that, in some binary systems, the two black holes have misaligned axes of rotation, which would imply that they formed separately. But many other binaries appear to have roughly aligned axes of rotation, which is what astrophysicists expect when the two black holes began their lives as a binary star system. Two schools of thought in astrophysics have each favoured one of the two scenarios, but it now appears that both were correct, Fishbach says.
Astrophysicists now have enough black-hole mergers to map their frequency over the cosmos’s history.
Only a few years ago, scientists the world over celebrated as the first-ever gravitational waves were detected—confirming a long-held scientific theory and opening up an entirely new field of research.
Now, the international research team responsible for detecting gravitational waves has announced a further 39 gravitational wave events, bringing the total number of confirmed detections to 50.
The Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo Collaborations, which include researchers from the University of Portsmouth, have today published a series of papers that record events including the mergers of binary black holes, binary neutron stars and, possibly, neutron star-black holes.
An international team of astronomers has identified one of the rarest known classes of gamma-ray emitting galaxies, called BL Lacertae, within the first 2 billion years of the age of the Universe. The team, that has used one of the largest optical telescope in the world, Gran Telescopio Canarias (GTC), located at the Observatorio del Roque de los Muchachos (Garafía, La Palma), consists of researchers from the Universidad Complutense de Madrid (UCM, Spain), DESY (Germany), University of California Riverside and Clemson University (USA). Their finding is published in The Astrophysical Journal Letters.
Only a small fraction of galaxies emits gamma rays, which are the most extreme form of light. Astronomers believe that these highly energetic photons originate from the vicinity of a supermassive black hole residing at the centers of these galaxies. When this happens, they are known as active galaxies. The black hole swallows matter from its surroundings and emits jets or, in other words, collimated streams of matter and radiation. Few of these active galaxies (less than 1%) have their jets pointing by chance toward Earth. Scientists call them blazars and are one of the most powerful sources of radiation in the universe.
Blazars come in two flavors: BL Lacertae (BL Lac) and flat-spectrum radio-quasars (FSRQs). Our current understanding about these mysterious astronomical objects is that FSRQs are relatively young active galaxies, rich in dust and gas that surround the central black hole. As time passes, the amount of matter available to feed the black hole is consumed and the FSRQ evolves to become a BL Lac object. “In other words, BL Lacs may represent the elderly and evolved phase of a blazar’s life, while FSRQs resemble an adult,” explains Vaidehi Paliya, a DESY researcher who participated in this program.
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:
A team of scientists have created a white paint that’s so white, they say, that it reflects 95.5 percent of sunlight that reaches its surface.
Essentially, it’s the exact opposite of Vantablack, the substance that makes objects appear so dark, by absorbing close to 100 percent of light that hits them, that it’s as if you’re staring into a black hole.
The team is hoping their invention could allow buildings to passively reflect most sunlight, thereby “rejecting heat.” In other words, it could allow us to keep interiors nice and cool without running energy-gobbling air conditioners.
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.
The team caught a glimpse of a process that takes 18,000,000,000,000,000,000,000 years.
Earlier this month, Roger Penrose, Reinhard Genzel, and Andrea Ghez split the 2020 physics Nobel Prize for decades of work on black holes. Click here to learn more about their monumental achievement and about the history of our understanding of these exotic objects in space.
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 fundamental constants. 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.