The universe can be a very sticky place, but just how sticky is a matter of debate. That is because for decades cosmologists have had trouble reconciling the classic notion of viscosity based on the laws of thermodynamics with Einstein's general theory of relativity. However, a team from Vanderbilt University has come up with a fundamentally new mathematical formulation of the problem that appears to bridge this long-standing gap.
NASA's Swift satellite detected a rising tide of high-energy X-rays from the constellation Cygnus on June 15, just before 2:32 p.m. EDT. About 10 minutes later, the Japanese experiment on the International Space Station called the Monitor of All-sky X-ray Image (MAXI) also picked up the flare.
Four hundred years ago, the astronomer Galileo's discovery of Jupiter's four large moons forever changed humanity's view of the universe, helping to bring about the understanding that Earth was not the center of all motion. Today one of these Galilean moons could again revolutionize science and our sense of place, for hidden beneath Europa's icy surface is perhaps the most promising place to look for present-day environments that are suitable for life.
There is growing interaction of the biosphere with the 'technosphere' - a concept pioneered by Peter Haff of Duke University - the sum total of all human-made manufactured machines and objects, and the systems that control them. In total, an international team of scientists team suggests that these changes represent a planetary transformation as fundamental as the one that saw the evolution of the photosynthetic microbes which oxygenated the planet 2.4 billion years ago, or that saw the transition from a microbial Earth to one dominated by multicellular organisms half a billion years ago.
One of the biggest questions in astrophysics is: does life exists beyond earth? To even begin answering this, we need to know how many planets like ours exist out there, and when they formed. However determining ages of stars (and thus of their orbiting planets) is extremely difficult; precise ages are only available for a handful of host stars thanks to asteroseismic observations made with the Kepler satellite.
The universe has slowed down and speeded up, not just once, but 7 times in the last 13.8 billion years, on average emulating dark matter in the process. “The ringing has been decaying and is now very small – much like striking a crystal glass and hearing it ring down," say physicists Lawrence Mead and Harry Ringermacher at The University of Southern Mississippi, who have discovered that the universe might not only be expanding, but also oscillating or “ringing” at the same time.
"The Planck data confirm the basic predictions that quantum fluctuations are at the origin of all structures in the Universe," said Jean-Loup Puget, Principal Investigator for the HFI-instrument on the Planck satellite. Viatcheslav Mukhanov, a cosmologist at Ludwig-Maximilians-Universitaet (LMU) in Munich, an expert in the field of Theoretical Cosmology., who first published his model in 1981 and joined the Physics Faculty at LMU in 1997, said: "I couldn't hope for a better verification of my theory."
For a planet, this would be like a day at the spa. After years of growing old, a massive planet could, in theory, brighten up with a radiant, youthful glow. Rejuvenated planets, as they are nicknamed, are only hypothetical. But new research from NASA's Spitzer Space Telescope has identified one such candidate, seemingly looking billions of years younger than its actual age.
New work from Carnegie's Alan Boss offers a potential solution to a longstanding problem in the prevailing theory of how rocky planets formed in our own Solar System, as well as in others. The snag he's untangling: how dust grains in the matter orbiting a young protostar avoid getting dragged into the star before they accumulate into bodies large enough that their own gravity allows them to rapidly attract enough material to grow into planets.
"Even if we never reach the stars by our own efforts, in the millions of years that lie ahead it is almost certain that the stars will come to us. Isolationism is neither a practical policy on the national or cosmic scale. And when the first contact with the outer universe is made, one would like to think that Mankind played an active and not merely a passive role—that we were the discoverers, not the discovered."
Astronomers expect that galaxies grow by swallowing smaller galaxies. But the evidence is usually not easy to see -- just as the remains of the water thrown from a glass into a pond will quickly merge with the pond water, the stars in the infalling galaxy merge in with the very similar stars of the bigger galaxy leaving no trace. Such is the case with Messier 87 lies at the center of the Virgo Cluster of galaxies. It is a vast ball of stars with a total mass more than a million million times that of the Sun, lying about 50 million light-years away.
"This cloud is very spectacular, though the evaporation rate does not threaten the planet right now," explains David Ehrenreich of the Observatory of the University of Geneva in Switzerland. "But we know that in the past, the star, which is a faint red dwarf, was more active. This means that the planet evaporated faster during its first billion years of existence because of the strong radiation from the young star. Overall, we estimate that it may have lost up to 10 percent of its atmosphere over the past several billion years."
When galaxies first assembled, during a period often referred to as 'Cosmic Dawn,' most of the space between the stars was filled with a mixture of hydrogen and helium produced in the Big Bang. As subsequent generations of massive stars ended their brief but brilliant lives as supernovas, they seeded the interstellar medium with a fine dust of heavy elements, mostly carbon, silicon, and oxygen, which are forged in their nuclear furnaces.
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In late 2013, when the neutron star at the heart of one of our galaxy's oddest supernovae gave off a massive burst of X-rays, the resulting echoes -- created when the X-rays bounced off clouds of dust in interstellar space -- yielded a surprising new measuring stick for astronomers. Circinus X-1 is a freak of the Milky Way. Located in the plane of the galaxy, it is the glowing husk of a binary star system that exploded a mere 2,500 years ago. The system consists of a nebula and a neutron star, the incredibly dense collapsed core of the exploded star, still in the orbital embrace of its companion star.
A new NASA computer simulation shows that dark matter particles colliding in the extreme gravity of a black hole can produce strong, potentially observable gamma-ray light. Detecting this emission would provide astronomers with a new tool for understanding both black holes and the nature of dark matter, an elusive substance accounting for most of the mass of the universe that neither reflects, absorbs nor emits light.
A group of researchers from the Stony Brook University (the State University of New York) and the National Astronomical Observatory of Japan has discovered 854 "ultra dark galaxies" in the Coma Cluster by analyzing archival data from the Subaru Telescope. The discovery of 47 such mysterious dark galaxies was a surprising find in 2014, and the new discovery of more than 800 suggests galaxy clusters as the key environment for the evolution of these mysterious dark galaxies. "Not only these galaxies appear very diffuse," said Jin Koda, principal investigator of the study, "but they are very likely enveloped by something very massive."
“In 5 billion years, the expansion of the universe will have progressed to the point where all other galaxies will have receded beyond detection. Indeed, they will be receding faster than the speed of light, so detection will be impossible. Future civilizations will discover science and all its laws, and never know about other galaxies or the cosmic background radiation. They will inevitably come to the wrong conclusion about the universe......We live in a special time, the only time, where we can observationally verify that we live in a special time.”
"It is hard to know how our future descendants will regard the little sliver of history that we live in. It is hard to know what events will seem important to them, what the narrative of now will look like to the twenty-fifth century mind. We tend to think of our time as one uniquely shaped by the advance of technology, but more and more I suspect that this will be remembered as an age of cosmology---as the moment when the human mind first internalized the cosmos that gave rise to it.
A swarm of 10,000 or more black holes may be orbiting the Milky Way's supermassive black hole, according to results from NASA's Chandra X-ray Observatory. This would represent the highest concentration of black holes anywhere in the Galaxy. These relatively small, stellar-mass black holes, along with neutron stars, appear to have migrated into the Galactic Center over the course of several billion years.
"A big misconception is that a black hole is made of matter that has just been compacted to a very small size. That's not true. A black hole is made from warped space and time. It may have been created by an imploding star [where the gravity becomes so concentrated that nothing, not even light, can escape]. But the star's matter is destroyed at the hole's center, where space-time is infinitely warped. There's nothing left anywhere but warped space-time.
It is thought that a majority of the galaxies in the universe have a massive black hole in the galactic center. Since these black holes have masses of several millions to tens of billions of solar masses, they are called "supermassive black holes (SMBHs)". Recent observation results suggest the correlation between the SMBH mass and the central bulge mass/luminosity of the host galaxy. Such correlation indicates that SMBHs may have played a key role in the growth and evolution of galaxies.
According to the professor of physics at The Ohio State University, the recently proposed idea that black holes have “firewalls” that destroy all they touch has a loophole. In a paper posted online to the arXiv preprint server, Mathur takes issue with the firewall theory, and proves mathematically that black holes are not necessarily arbiters of doom.In fact, he says the world could be captured by a black hole, and we wouldn’t even notice.