BIG GULP Gravitational waves may have revealed a black hole in the process of swallowing up a neutron star (illustrated). If confirmed, the event would be the first of its kind ever seen.
Category: cosmology – Page 362
SUPERNOVA SNOWFALL Scientists have found a fingerprint of exploding stars, or supernovas, in Antarctic snow that fell within the last 20 years. Here, part of a supernova remnant, Vela, is shown.
The EOR will also provide an unprecedented test for the current best model of cosmic evolution. Although there is plenty of evidence for dark matter, nobody has identified exactly what it is. Signals from the EOR would help to indicate whether dark matter consists of relatively sluggish, or ‘cold’, particles — the model that is currently favoured — or ‘warm’ ones that are lighter and faster, says Anna Bonaldi, an astrophysicist at the Square Kilometre Array (SKA) Organisation near Manchester, UK. “The exact nature of dark matter is one of the things at stake,” she says.
Radioastronomers look to hydrogen for insights into the Universe’s first billion years.
Figuring out how our reality took shape over billions of years is no easy task for scientists. Theories about how the Big Bang played out and the immediate aftermath are a dime a dozen, but researchers led by a team from the University of Arizona think they might stumble upon some of the secrets of galaxy formation by asking a supercomputer to simulate millions of virtual universes and seeing which ones come closest to what we see today.
In a new research paper published in Monthly Notices of the Royal Astronomical Society, the team explains how they used a supercomputer system nicknamed the “Universe Machine” to watch billions of (virtual) years of galaxy formation play out before their eyes.
Astronomer Dr David Whitehouse said the “enormous” black hole discovered by astronomers in South America showed the whole universe might one day be swallowed by a black hole. He told Sky News: “We’re beginning to realise that we had thought that there was a limit to the size of black holes in the centre of a galaxy because they can only swallow so many stars. Black holes grow by swallowing matter and gas and stars and dust.
A method for locating seams of gold and other heavy metals is the unlikely spin-off of Swinburne’s involvement in a huge experiment to detect dark matter down a mine in Stawell, Victoria.
Associate Professor Alan Duffy, from Swinburne’s Centre for Astrophysics and Supercomputing and a member of the Sodium iodide with Active Background REjection (SABRE) project, said cosmic radiation was effectively creating an X-ray of the Earth between the underground detector and the surface.
In the mine, the SABRE experiment seeks to detect particles of dark matter, something no one has conclusively achieved yet. Any signal from dark matter would be miniscule, and so the SABRE team created a phenomenally sensitive detector, which, it turns out, is also sensitive to a host of cosmic particles that can help us to locate gold.
Dark matter most likely makes up an incredible 80 percent of the universe’s mass. But this single fact is the extent of our knowledge about this mysterious, all pervasive substance, with scientists unsure exactly what it is and how it came to be. Now a groundbreaking study has revealed dark matter may be even more bizarre than first thought, as its origin may have actually pre-dated the beginning of the Universe – the Big Bang.
The supermassive black hole at the heart of our galaxy has suddenly started flashing brighter than we have ever seen it, and astronomers don’t know why.
Pour milk in coffee, and the eddies and tendrils of white soon fade to brown. In half an hour, the drink cools to room temperature. Left for days, the liquid evaporates. After centuries, the cup will disintegrate, and billions of years later, the entire planet, sun and solar system will disperse. Throughout the universe, all matter and energy is diffusing out of hot spots like coffee and stars, ultimately destined (after trillions of years) to spread uniformly through space. In other words, the same future awaits coffee and the cosmos.
This gradual spreading of matter and energy, called “thermalization,” aims the arrow of time. But the fact that time’s arrow is irreversible, so that hot coffee cools down but never spontaneously heats up, isn’t written into the underlying laws that govern the motion of the molecules in the coffee. Rather, thermalization is a statistical outcome: The coffee’s heat is far more likely to spread into the air than the cold air molecules are to concentrate energy into the coffee, just as shuffling a new deck of cards randomizes the cards’ order, and repeat shuffles will practically never re-sort them by suit and rank. Once coffee, cup and air reach thermal equilibrium, no more energy flows between them, and no further change occurs. Thus thermal equilibrium on a cosmic scale is dubbed the “heat death of the universe.”
But while it’s easy to see where thermalization leads (to tepid coffee and eventual heat death), it’s less obvious how the process begins. “If you start far from equilibrium, like in the early universe, how does the arrow of time emerge, starting from first principles?” said Jürgen Berges, a theoretical physicist at Heidelberg University in Germany who has studied this problem for more than a decade.
