Black holes occasionally reveal themselves when passing stars get ripped apart by their gravity. These tidal disruption events have created a new way for astronomers to map the hidden cosmos.
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Category: cosmology
Next time you eat a blueberry (or chocolate chip) muffin consider what happened to the blueberries in the batter as it was baked. The blueberries started off all squished together, but as the muffin expanded they started to move away from each other. If you could sit on one blueberry you would see all the others moving away from you, but the same would be true for any blueberry you chose. In this sense galaxies are a lot like blueberries.
Since the Big Bang, the universe has been expanding. The strange fact is that there is no single place from which the universe is expanding, but rather all galaxies are (on average) moving away from all the others. From our perspective in the Milky Way galaxy, it seems as though most galaxies are moving away from us – as if we are the centre of our muffin-like universe. But it would look exactly the same from any other galaxy – everything is moving away from everything else.
To make matters even more confusing, new observations suggest that the rate of this expansion in the universe may be different depending on how far away you look back in time. This new data, published in the Astrophysical Journal, indicates that it may time to revise our understanding of the cosmos.
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Much research on black holes is theoretical since it is difficult to make actual measurements on real black holes. Such experiments also need to be undertaken over decades or longer. Physicists are therefore keen to create laboratory systems that are analogous to these cosmic entities. New theoretical calculations by a team in Canada, the US, UK and Israel have now revealed that a material as simple as a graphene flake with an irregular boundary subjected to an intense external magnetic field can be used to create a quantum hologram that faithfully reproduces some of the signature characteristics of a black hole. This is because the electrons in the carbon material behave according to the Sachdev-Ye-Kitaev model.
Some of the most important unresolved mysteries in modern physics come from the “incompatibility” between Einstein’s theory of general relativity and the theory of quantum mechanics. General relativity describes the physics of the very big (the force of gravity and all that it affects: spacetime, planets, galaxies and the expansion of the Universe). The theory of quantum mechanics is the physics of the very small – and the other three forces, electromagnetism and the two nuclear forces.
“In recent years, physicists have gleaned important new insights into these questions through the study of the SYK model,” explains Marcel Franz of the University of British Columbia in Canada, who led this research effort. “This model is an illustration of a type of ‘holographic duality’ in which a lower-dimensional system can be represented by a higher dimensional one. In our calculations, the former is N graphene electrons in (0+1) dimensions and the latter the dilation gravity of a black hole in (1+1) dimensional anti-de Sitter (AdS2) space.
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This video takes the viewer on a tour of a 3D image of the supernova 1987 A, created using data collected by the international astronomy facility ALMA. The p urple area indicates emission from SiO molecules and the yellow area indicates emission from CO molecules. The blue ring is NASA/ESA Hubble Space Telescope data that has been artificially expanded into 3D.
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Observations made with ESO’s Very Large Telescope have for the first time revealed the effects predicted by Einstein’s general relativity on the motion of a star passing through the extreme gravitational field near the supermassive black hole in the center of the Milky Way. This long-sought result represents the climax of a 26-year-long observation campaign using ESO’s telescopes in Chile.
Credit: European Space Observatory
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Love is a burning thing and it makes a fiery ring. Black holes, however, do not.
New research disproves the so-called “firewall” theory, which suggests the ring of fire around a supernova would incinerate anything sucked into its gravitational pull.
A team from Ohio State University determined what would actually happen if an electron fell into a black hole with a mass as big as the Sun.
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With more than 5.6 million articles, Wikipedia is an invaluable resource, whether you’re throwing a term paper together at the last minute, or doing legal research on whether it can really be considered assault if your victim habitually made the “cows outstanding in their field” joke. We explore some of Wikipedia’s oddities in our 5,690,195-week series, Wiki Wormhole.
This week’s entry: Vertical farming
What it’s about: Ah, the farmer’s life. The smell of the soil, the green of the leaves, the view from the 45th floor. Yes, like bathrooms before them, farms are moving into the future by moving indoors. Hydroponic farming has made vertical farms possible, in which floor after floor of a building is devoted to growing food. One such farm in Buffalo, New York contains 17 million plans, and a “windowless farm” in Kyoto produces 6 million heads of lettuce a year.
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