Nov 28, 2019
Why Humans Should Be Thankful That Our Universe Has Dark Matter
Posted by Paul Battista in category: cosmology
Without this one ingredient, there wouldn’t be enough ‘glue’ to hold the Universe together.
Without this one ingredient, there wouldn’t be enough ‘glue’ to hold the Universe together.
The problem of surviving the end of the observable universe may seem very remote, but there are several reasons it may be important now: a) we may need to define soon the final goals of runaway space colonization and of superintelligent AI, b) the possibility of the solution will prove the plausibility of indefinite life extension, and с) the understanding of risks of the universe’s end will help us to escape dangers like artificial false vacuum decay. A possible solution depends on the type of the universe’s ending that may be expected: very slow heat death or some abrupt end, like a Big Rip or Big Crunch. We have reviewed the literature and identified several possible ways of survival the end of the universe, and also suggest several new ones. There are seven main approaches to escape the end of the universe: use the energy of the catastrophic process for computations, move to a parallel world, prevent the end, survive the end, manipulate time, avoid the problem entirely or find some meta-level solution.
A new black hole search method has just yielded fruit, and boy is it juicy. Astronomers have found a stellar-mass black hole clocking in at around 70 times the mass of the Sun — but according to current models of stellar evolution, its size is impossible, at least in the Milky Way.
The chemical composition of our galaxy’s most massive stars suggests that they lose most of their mass at the end of their lives through explosions and powerful stellar winds, before the star’s core collapses into a black hole.
The hefty stars in the mass range that could produce a black hole are expected to end their lives in what is called a pair-instability supernova that completely obliterates the stellar core. So astronomers are scratching their heads trying to figure out how the black hole — named LB-1 — got so chonky.
A pair of physicists from Immanuel Kant Baltic Federal University (IKBFU) in Russia recently proposed an entirely new view of the cosmos. Their research takes the wacky idea that we’re living in a computer simulation and mashes it up with the mind-boggling “many worlds” theory to say that, essentially, our entire universe is part of an immeasurably large quantum system spanning “uncountable” multiverses.
When you think about quantum systems, like IBM and Google’s quantum computers, we usually imagine a device that’s designed to work with subatomic particles – qubits – to perform quantum calculations.
Here might be cracks in space-time, but humanity’s telescopes can’t see them.
The cracks, if they exist, are old, remnants of a time shortly after the Big Bang. But a new paper shows they might be too faint to detect.
New books by a physicist and science journalist mount aggressive but ultimately unpersuasive defenses of multiverses.
Supermassive black holes are true monsters of the Universe. From millions to even billions of times the mass of the Sun, there’s one in the very center of every big galaxy in the cosmos, and in fact each galaxy itself formed and grew along with its black hole; they affect each other profoundly. As matter falls onto the black hole it falls into an accretion disk, heats up, and emits huge amounts of energy and can also blow a fierce wind of material back into the galaxy (we call such galaxies with actively feeding supermassive black holes active galaxies). This wind can push away gas and dust that would otherwise fall onto the black hole, regulating its growth.
Under some conditions this wind can also compress the gas in the galaxy, which can increase the number of stars forming in the galaxy. But too much wind and the gas is blown right out of the galaxy. Even at some levels in between, it can heat the gas up enough that star formation is much harder. It’s like a pressure valve in the galaxy.
This is how it usually works, at least. Astronomers have found a compact group of galaxies clustered around an active galaxy, and that central galaxy’s black hole is so powerful it’s blowing a wind that’s causing star formation in the galaxies around it!
A typical but existentially terrifying feature of almost every galaxy is a monster lurking at its center: A supermassive black hole which can be hundreds or even billions of times the mass of our sun. The supermassive black hole sucks in dust and gas from the surrounding galaxy, leaving an empty spheroid shape right in the middle of the galaxy from which not even light can escape.
Very occasionally, astronomers spot not one but two of these hungry giants moving together, typically when they observe two galaxies merging. But now, researchers have spotted something utterly unprecedented: A galaxy with three supermassive black holes at its heart.
Dr. Peter Weilbacher, one of the researchers from the Leibniz Institute for Astrophysics Potsdam, underlined the significance of this finding: “Up until now, such a concentration of three supermassive black holes had never been discovered in the universe,” he said.
The shape of our Universe has long been recognized to be flat. But that isn’t the only possibility.