The big bang poses a big question: if it was indeed the cataclysm that blasted our universe into existence 13.7 billion years ago, what sparked it? Three researchers at the Perimeter Institute for Theoretical Physics and the University of Waterloo propose that the big bang could be the three-dimensional “mirage” of a collapsing star in a universe profoundly different than our own.
An international team of astronomers have discovered a ‘cosmic one-two punch’ in the night sky that has never been seen before. In one image, the team managed to spot a supermassive black hole and two gigantic galaxy clusters colliding at the same time.
Matter ejected from the black hole gets caught up inside the violent galactic collisions, turning this dynamic duo into one hell of an enormous cosmic particle accelerator.
“We have seen each of these spectacular phenomena separately in many places,” said team leader Reinout van Weeren, from the Harvard-Smithsonian Centre for Astrophysics.
NASA’s Chandra X-ray Observatory has completed the deepest X-ray image ever obtained, made with over 7 million seconds of observing time revealing the best picture ever at the growth of black holes over billions of years beginning soon after the Big Bang. The central region of the image contains the highest concentration of supermassive black holes ever seen, equivalent to about 5,000 objects that would fit into the area of the full Moon and about a billion over the entire sky.
We examine the effect of the stress tensor of a quantum matter field, such as the electromagnetic field, on the spectrum of primordial gravity waves expected in inflationary cosmology. We find that the net effect is a small reduction in the power spectrum, especially at higher frequencies, but which has a different form from that described by the usual spectral index. Thus this effect has a characteristic signature, and is in principle observable. The net effect is a sum of two contributions, one of which is due to quantum fluctuations of the matter field stress tensor. The other is a quantum correction to the graviton field due to coupling to the expectation value of this stress tensor. Both contributions are sensitive to initial conditions in the very early universe, so this effect has the potential to act as a probe of these initial conditions.
J. Hsiang, L. Ford, K. Ng, et. al. Thu, 5 Jan 17 31/58.
The 2015 Planck data release tightened the region of the allowed inflationary models. Inflationary models with convex potentials have now been ruled out since they produce a large tensor to scalar ratio. Meanwhile the same data offers interesting hints on possible deviations from the standard picture of CMB perturbations. Here we revisit the predictions of the theory of the origin of the universe from the landscape multiverse for the case of exponential inflation, for two reasons: firstly to check the status of the anomalies associated with this theory, in the light of the recent Planck data; secondly, to search for a counterexample whereby new physics modifications may bring convex inflationary potentials, thought to have been ruled out, back into the region of potentials allowed by data. Using the exponential inflation as an example of convex potentials, we find that the answer to both tests is positive: modifications to the perturbation spectrum and to the Newtonian potential of the universe originating from the quantum entanglement, bring the exponential potential, back within the allowed region of current data; and, the series of anomalies previously predicted in this theory, is still in good agreement with current data. Hence our finding for this convex potential comes at the price of allowing for additional thermal relic particles, equivalently dark radiation, in the early universe.
E. Valentino and L. Mersini-Houghton Wed, 28 Dec 16 26/46.
A new supercomputer has been deployed at the Jülich Supercomputing Center (JSC) in Germany. Called QPACE3, the new 447 Teraflop machine is named for “QCD Parallel Computing on the Cell.”
QPACE3 is being used by the University of Regensburg for a joint research project with the University of Wuppertal and the Jülich Supercomputing Center for numerical simulations of quantum chromodynamics (QCD), which is one of the fundamental theories of elementary particle physics. Such simulations serve, among other things, to understand the state of the universe shortly after the Big Bang, for which a very high computing power is required.
The demand for high performance computers to solve complex applications has risen exponentially, but unfortunately so has their consumption of power. Many supercomputers require more than a megawatt of electricity to operate and annual electricity costs can easily run into millions of Euros. The energy supply is therefore a significant part of the operating costs of a data center. According to recent analyst studies, this represents the second-largest factor in addition to personnel and maintenance costs. The upcoming boom with (3D) video streaming, augmented reality, image recognition and artificial intelligence is driving up the demand for data center capabilities, thereby placing new challenges in the power supply sector.
Dark matter is a mysterious substance composing most of the material universe, now widely thought to be some form of massive exotic particle. An intriguing alternative view is that dark matter is made of black holes formed during the first second of our universe’s existence, known as primordial black holes.
Verlinde’s emergent gravity theory makes one very important implication: dark matter does not exist. His research makes sense of the behavior of gravity without the need for the existence of a dark matter particle.
Researchers from the Leiden Observatory have studied more than 33,000 galaxies to see if Verlinde’s theory checks out—and the results show that it is, in fact, more accurate at confirming the universe’s gravity distribution than Einstein’s theory of relativity.
Watch the video below to know more about Verlinde’s alternate explanation to gravity.
