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Cosmology
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Conventional wisdom says that the Big Bang was the start of everything, including time, so questions about the Big Bang itself, or what came before, don't make sense. Or so we're told. But the breakdown in the laws of physics — the singularity problem — limits what we know about the starting conditions of the Universe. In the loop quantum universe everything is quantized, or discrete, including time. Freed from the singularity, Bojowald can now look back to a time 'before' the Big Bang. He finds an inverted universe on the other side — a mirror-image of ours — expanding outwards as time runs backwards.
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Scientists are incorporating the physics of black holes into a highly sophisticated model running on a powerful supercomputing system. The team has produced an unprecedented simulation of cosmic evolution that verifies and deepens our understanding of relationships between black holes and the galaxies in which they reside. Called BHCosmo, the simulation shows that black holes are integral to the structure of the cosmos and may help guide users of future telescopes, showing them what to look for as they aim to locate the earliest cosmic events and untangle the history of the universe.
"Ours is the first simulation to incorporate black hole physics. It is very computationally challenging, involving more calculations than any prior similar modeling of the cosmos, and the result offers us the best picture to date of how the cosmos formed."
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The mysterious dark matter that fills the universe could be made of the same particles that put the "big" in the big bang - explaining both inflation and dark matter in a single stroke.
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UK astronomers announced this month the discovery of cannibalistic stars that explain one of the mysteries surrounding the Big Bang. The stars are almost as old as the Universe and they reveal what space was like in the very beginning. The team from the Open University found that a group of 14-billion-year-old stars were all in a spin (literally) because of a nasty phase earlier in their lives. They were, in short, cannibalistic stars. Some of the stars that formed early in the life of the Universe were very unusual. They contained none of the metal lithium which astronomers believe is produced in the Big Bang.
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 The measurement of the cosmic microwave background has strongly constrained the cosmological parameters of the Universe. When the measured density of baryons (ordinary matter) is combined with standard Big Bang nucleosynthesis calculations, the amounts of hydrogen, helium and lithium produced shortly after the Big Bang can be predicted with unprecedented precision. The predicted primordial lithium abundance is a factor of two to three higher than the value measured in the atmospheres of old stars. With estimated errors of 10 to 25%, this cosmological lithium discrepancy seriously challenges our understanding of stellar physics, Big Bang nucleosynthesis or both. Certain modifications to nucleosynthesis have been proposed, but found experimentally not to be viable. Diffusion theory, however, predicts atmospheric abundances of stars to vary with time, which offers a possible explanation of the discrepancy. Here we report spectroscopic observations of stars in the metal-poor globular cluster NGC 6397 that reveal trends of atmospheric abundance with evolutionary stage for various elements. These element-specific trends are reproduced by stellar-evolution models with diffusion and turbulent mixing. We thus conclude that diffusion is predominantly responsible for the low apparent stellar lithium abundance in the atmospheres of old stars by transporting the lithium deep into the star.
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 Scientists have discovered a warm and rocky "second Earth" circling a star, a find they believe dramatically boosts the prospects that we are not alone.
The planet is the most Earth-like ever spotted and is thought to have perfect conditions for water, an essential ingredient for life. Researchers detected the planet orbiting one of Earth's nearest stars, a cool red dwarf called Gliese 581, 20 light years away in the constellation of Libra.
Measurements of the planet's celestial path suggest it is 1½ times the size of our home planet, and orbits close to its sun, with a year of just 13 days. The planet's orbit brings it 14 times closer to its star than Earth is to the sun. But Gliese 581 burns at only 3,000C, half the temperature of our own sun, making conditions on the planet comfortable for life, with average ground temperatures estimated at 0 to 40C. Researchers claim the planet is likely to have an atmosphere. The discovery follows a three-year search for habitable planets by the European Southern Observatory at La Silla in Chile.
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A giant hole in the Universe is devoid of galaxies, stars and even lacks dark matter, astronomers said on Thursday.
The team at the University of Minnesota said the void is nearly a billion light-years across and they have no idea why it is there.
"What we've found is not normal, based on either observational studies or on computer simulations of the large-scale evolution of the Universe."
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Happy birthday, Universe!
Kinda. It’s not really the Universe’s birthday, but now we do know to high accuracy just how old it is.
How?
NASA’s WMAP is the Wilkinson Microwave Anisotropy Probe (which is a mouthful, and why we just call it WMAP). It was designed to map the Universe with exquisite precision, detecting microwaves coming from the most distant source there is: the cooling fireball of the Big Bang itself.
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In our first semester of astronomy we were concerned primarily with our own Solar System. In this semester we broaden our perspective and consider the entire Universe. Much of the material for this semester is already on the Web at the Violence in the Cosmos site, but it is arranged in a different order than it will be when the following sequence is completed.
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Lithium is one of the elements (with deuterium) formed primarily during the primordial nucleosynthesis, a few minutes after the Big-Bang. Its abundance thus allows to determine the quantity of baryons in the Universe. It proves that the density of baryons deduced (or its value Omega-b normalized to the critical density to close the Universe) is much larger than the one visible by radiation. It is therefore essential to better constrain this density of baryons. A recent work on the ESO-VLT of an international consortium, in which take part several astronomers of the Paris Observatory, brings confirmation of the constancy of the lithium abundance in stars, which suggests that the abundance observed is quite close to the primordial abundance, and thus makes it possible to refine the determination of Omega-b.
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The Microwave Sky. Content of the Universe. Time Line of the Universe. Temperature Fluctuation by Angular Size.
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