A new paradigm shift for the infant universe
A new paradigm for understanding the earliest eras in the history of the universe has been developed by scientists at Penn State University. Using techniques from an area of modern physics called loop quantum cosmology, developed at Penn State, the scientists now have extended analyses that include quantum physics farther back in time than ever before—all the way to the beginning. The new paradigm of loop quantum origins shows, for the first time, that the large-scale structures we now see in the universe evolved from fundamental fluctuations in the essential quantum nature of “space-time,” which existed even at the very beginning of the universe over 14 billion years ago. The achievement also provides new opportunities for testing competing theories of modern cosmology against breakthrough observations expected from next-generation telescopes. The research will be published on 11 December 2012 as an “Editor’s Suggestion” paper in the scientific journal Physical Review Letters.
Read more at: phys.org
Prediction and control of the dynamics of complex networks is a central problem in network science. Structural and dynamical similarities of different real networks suggest that some universal laws might accurately describe the dynamics of these networks, albeit the nature and common origin of such laws remain elusive. Here we show that the causal network representing the large-scale structure of spacetime in our accelerating universe is a power-law graph with strong clustering, similar to many complex networks such as the Internet, social, or biological networks. We prove that this structural similarity is a consequence of the asymptotic equivalence between the large-scale growth dynamics of complex networks and causal networks. This equivalence suggests that unexpectedly similar laws govern the dynamics of complex networks and spacetime in the universe, with implications to network science and cosmology.
Read more: nature.com
Although stars themselves are hot, they can only form out of the coldest gas when a massive cloud of hydrogen can collapse under its own gravity until nuclear fusion starts – the fusing of atoms together which releases the huge amounts of energy we see as starlight.
Astronomers have been puzzled as to why they could not detect this cold star-forming gas in the most distant, and hence older, regions of the Universe.
At such vast look-back times, astronomers expected the gas to be much more abundant as it has yet to be consumed by star formation.
Dr Stephen Curran, from the University of Sydney’s School of Physics and CAASTRO – the ARC Centre for All-sky Astrophysics – and Dr Matthew Whiting, from CSIRO Astronomy and Space Science, have addressed this problem by devising a model that shows how the supermassive black hole, lurking within the centre of each active galaxy, is able to ionise all of the surrounding gas even in the very largest galaxies.
When hydrogen gas is in this state, where the electron is ripped out of the atom, the gas it too agitated to allow the cloud to collapse and form stars. Also, when ionised, it cannot be detected through radio waves at 21-centimetres – the way cold star-forming gas is normally found. “Previously, we had not known just how much of the gas was ionised by the black hole accretions disks – we had thought that perhaps it was just enough to take the abundance of cool gas to below the detection threshold of current radio telescopes.
So we’d thought that it was maybe a telescope sensitivity issue,” said Dr Curran. Dr Curran and Dr Whiting’s latest research, published in The Astrophysical Journal on 10 November 2012, shows that the extreme ultra-violet radiation given off by the material being sucked in – at near light-speeds – to the black hole, is sufficient to ionise all of the gas in even the very largest galaxies. “In order to probe further back in time, we choose the most distant radio sources. What appears as faint light from these, to us on Earth, is actually extreme ultra-violet, dimmed and stretched (redshifted) to visible light on its several billion year journey to us,” explained Dr Curran. “Unfortunately, these are the only objects we know of at the very limits of the cosmos and within these the radiation from the central black hole is so intense as to heat all the gas to the point where it cannot form stars. “We have shown that rather than being a telescope sensitivity issue, all of the billions of suns worth of gas is indeed ionised.
This means that even the Square Kilometre Array – the biggest radio telescope, which is currently being built in Australia, New Zealand and southern Africa – will not be able to detect star-forming gas in these galaxies,” said Dr Curran. “The Square Kilometre Array will excel, however, in detecting very cold gas that is too faint to be detected by optical telescopes, which must have existed to give us the stars and galaxies we see today.”
Read more at: phys.org
Berkeley Lab’s Science at the Theater traveled across the Bay to San Francisco’s Herbst Theater on Oct. 22, 2012 for a star turn by two of the Lab’s Nobel laureates. George Smoot received the 2006 Nobel Prize in Physics for the “discovery of the blackbody form and anisotropy of the cosmic microwave background radiation.” Saul Perlmutter received the 2011 Nobel Prize in Physics for “for the discovery of the accelerating expansion of the Universe through observations of distant supernovae.” The host for the conversation was KQED’s Michael Krasny.
The Known Universe takes viewers from the Himalayas through our atmosphere and the inky black of space to the afterglow of the Big Bang. Every star, planet, and quasar seen in the film is possible because of the world’s most complete four-dimensional map of the universe, the Digital Universe Atlas that is maintained and updated by astrophysicists at the American Museum of Natural History.
The new film, created by the Museum, is part of an exhibition, Visions of the Cosmos: From the Milky Ocean to an Evolving Universe, at the Rubin Museum of Art in Manhattan through May 2010. Data: Digital Universe, American Museum of Natural History haydenplanetarium.org/universe/ Visualization Software: Uniview by SCISS Director: Carter Emmart Curator: Ben R. Oppenheimer Producer: Michael Hoffman Executive Producer: Ro Kinzler Co-Executive Producer: Martin Brauen Manager, Digital Universe Atlas: Brian Abbott Music: Suke Cerulo