"How The Universe Works" Are Black Holes Real(2... ((EXCLUSIVE))
Black holes are laboratories for testing fundamental theories that explain how the Universe works on the largest and the smallest scales (e.g., GR and Quantum Physics). While each of these theories works well in its respective regime, physicists currently do not understand how to create a single physical theory that would be universal and, hence, explain the physics of black holes in detail. With the EHT results, scientists are able to directly resolve the conditions of spacetime at the black hole boundary.
"How the Universe Works" Are black holes real(2...
Astronomers think that the energy that forms when galactic masses swirl and heat up around a black hole shoots out in X-ray beams that fuel quasars, supermassive black holes that are actively chomping down gas at the centers of distant galaxies.
In the search for the smallest particles in the universe, the consequential mini black holes that scientists might create in contained underground tubes would let them observe general relativity and quantum mechanics in action and may open the door to solving the firewall paradox.
Knowing how the laws of physics behave at the extremes of space and time, near a black hole or a neutron star, is also an important piece of the puzzle we must obtain if we are to understand how the universe works. Current observatories operating at X-ray and gamma-ray energies, such as the Chandra X-ray Observatory, NuSTAR, Fermi Gamma-ray Space Telescope, and ESA's XMM-Newton, are producing a wealth of information on the conditions of matter near compact sources, in extreme gravity fields unattainable on Earth.
Astronomers are hoping to tease out which of these origin stories is more likely by analyzing the 69 confirmed binaries detected to date. But a new study finds that for now, the current catalog of binaries is not enough to reveal anything fundamental about how black holes form.
"When you change the model and make it more flexible or make different assumptions, you get a different answer about how black holes formed in the universe," says study co-author Sylvia Biscoveanu, an MIT graduate student working in the LIGO Laboratory. "We show that people need to be careful because we are not yet at the stage with our data where we can believe what the model tells us."
Black holes in binary systems are thought to arise via one of two paths. The first is through "field binary evolution," in which two stars evolve together and eventually explode in supernovae, leaving behind two black holes that continue circling in a binary system. In this scenario, the black holes should have relatively aligned spins, as they would have had time -- first as stars, then black holes -- to pull and tug each other into similar orientations. If a binary's black holes have roughly the same spin, scientists believe they must have evolved in a relatively quiet environment, such as a galactic disk.
Black hole binaries can also form through "dynamical assembly," where two black holes evolve separately, each with its own distinct tilt and spin. By some extreme astrophysical processes, the black holes are eventually brought together, close enough to form a binary system. Such a dynamical pairing would likely occur not in a quiet galactic disk, but in a more dense environment, such as a globular cluster, where the interaction of thousands of stars can knock two black holes together. If a binary's black holes have randomly oriented spins, they likely formed in a globular cluster.
To date, astronomers have derived the spins of black holes in 69 binaries, which have been discovered by a network of gravitational-wave detectors including LIGO in the U.S., and its Italian counterpart Virgo. Each detector listens for signs of gravitational waves -- very subtle reverberations through space-time that are left over from extreme, astrophysical events such as the merging of massive black holes.
With each binary detection, astronomers have estimated the respective black hole's properties, including their mass and spin. They have worked the spin measurements into a generally accepted model of black hole formation, and found signs that binaries could have both a preferred, aligned spin, as well as random spins. That is, the universe could produce binaries in both galactic disks and globular clusters.
The team first reproduced LIGO's spin measurements in a widely used model of black hole formation. This model assumes that a fraction of binaries in the universe prefer to produce black holes with aligned spins, where the rest of the binaries have random spins. They found that the data appeared to agree with this model's assumptions and showed a peak where the model predicted there should be more black holes with similar spins.
They then tweaked the model slightly, altering its assumptions such that it predicted a slightly different orientation of preferred black hole spins. When they worked the same data into this tweaked model, they found the data shifted to line up with the new predictions. The data also made similar shifts in 10 other models, each with a different assumption of how black holes prefer to spin.
But let's step back for a second here and explain what gravitational waves actually are. According to Einstein's theory, the fabric of space-time can become curved by anything massive in the Universe. When cataclysmic events happen, such as black holes merging or stars exploding, these curves can ripple out elsewhere as gravitational waves, just like if someone had dropped a stone in a pond.
10.37am ET: We're watching a video of the two black holes spiralling around each other and eventually merging, triggering the gravitational waves. This is the first time a binary black hole merger has ever been seen.
10.38am ET: The black holes were about 30 times the mass of the Sun and accelerated to half the speed of light when they smashed into each other, just to give you a sense of how big the collision was!
11.06am ET: OK now we're seeing a simulation of how the gravitational waves actually originated from the merging of two black holes. The total power output in gravitational waves during the brief collision of these black holes was 50 times greater than all of the power put out by all of the stars of the Universe put together. Whoa.
It's an apt name, considering it's likely referencing a previous attempt to reconcile the two theories, the "no hair theorem" first suggested by American theoretical physicist John Wheeler in the 1960s. At the time, Wheeler claimed black holes were "bald" and had no other physical features beyond mass, electric charge, and spin.
To give you an example, on the second episode they state that there are massive black holes at the center of galaxies. From my perspective (i.e. of someone which is not an astronomer) if they say so it's because it's probably true. However, in the real world maybe this is a highly disputed theory and a lot of astronomers disagree with this stance, and they're note telling the audience about it. Why would they do that? I don't know. I don't know if they did, I'm just asking if someone knows whether it happened, or if anyone saw something in the series with which they disagree.
On Sept. 14, 2015, University of Chicago scientists were part of the international team to make the first direct detection of ripples in the fabric of space-time from the collision of two black holes 1.4 billion light years away.
"Black Holes and Baby Universes (opens in new tab)" (Bantam Press, 1993) is a collection of Hawking's essays, ranging from the scientific, such as the makeup of black holes, to the personal, such as his experiences growing up and life with a neurodegenerative disorder.
"How the Universe Works" is the ultimate cosmos operator's manual, a revealing look at the inner workings of outer space. Computer imagery allows viewers to explore black holes, supernovas, neutron stars, dark energy, and all of the other forces that produce what exists and what people see.
Imagine two very massive objects, such as black holes. If those objects were to collide, they could potentially create an extreme disturbance in the fabric of spacetime, moving outwards like the ripples in a pond. But how far away could such waves be felt? Einstein predicted that gravitational waves existed, but believed they would be too small to detect by the time they reached us here on Earth.
A PHY 442 Introduction to General Relativity (3)Review of Special Relativity. Introduction to tensor analysis and the geometry of curved spaces. Einstein's equations. Applications to gravitational waves, black holes and expanding universes. Prerequisite: A PHY 320.A PHY 443/443Y Introduction to Cosmology (3)An introduction to cosmology, the study of the structure and evolution of the Universe. Topics: Newtonian cosmology, elements of general relativity (metric, geodesics, Einstein equations), Friedman equations and their solutions, dark matter, dark energy, inflation, introduction to quantum gravity. Only one version may be taken for credit. Prerequisite(s): A PHY 320 or permission of instructor. 041b061a72