All you need to know about…. Black Holes!
April 17, 2017
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In the center of the Milky Way, a behemoth 4 million times larger than the sun resides. Sagittarius A is a supermassive black hole that lies 53.5 million light years away from Earth, which scientists are attempting to photograph with new radio technology. The history of black holes is intense and full of debate, and most of the things which have been discovered have only lead to more questions to be answered. Black holes are full of mysteries, where do they come from, what would happen if you fell into one, how do we know they exist if they can’t be photographed, and what are they are just a few.
A black hole is not actually a hole, it is an extraordinarily compact object with enough mass in a small volume to create a gravitational pull strong enough that nothing, even light, can escape. Using the basic laws of gravity the theory of black holes was first proposed in the 18th century by John Michell and Pierre-Simon Laplace who worked independently. Although Pierre-Simon Laplace is often credited with the discovery of the black hole, John Michell actually made the discovery a couple of years before him. John Michell worked off of Newton’s laws of gravity, mainly the equation he designed which calculated the escape velocityVesc=2GM/d. He discovered that if an object had a large enough mass in a small enough volume that not even something as fast as light could escape. He called his discovery a dark star, but this theory is the basic concept between the black hole.
The sizes of black holes can vary, and in theory scientists believe that they can range from the size of an atom to supermassive black holes which can be several million times larger than the sun. The current theory is that there are three classifications of black holes, stellar, supermassive and miniature. A stellar black hole is created when an enormous star collapses in on itself. This process occurs during a supernova explosion as the core of the star collapses inward when energy production stops. If the mass of the star is 2-3 solar masses than the pressure of the collapse is not able to be stopped and a black hole will form. Supermassive black holes contain between a million and billion times as much mass as the average stellar black hole. Various sources have found that they radiate up to a trillion times more energy than our sun in an area about the size of the solar system, and that a supermassive black hole is located in the center of every large galaxy. No miniature black holes have been proven to exist but they may have been created during the big bang and have the width of an atom.
Near the center of a black hole is something called an event boundary, or the point at which even light cannot escape and is inevitably pulled in. Outside of the event horizon, if something is fast enough it can escape, but because light is the fastest known thing to man*, past the event horizon nothing has the chance of escaping. Because of the fact that not even light can escape past the event horizon scientists have not been able to do much research about the actual contents of a black hole. Stephen Hawking does great research into the subject, and is particularly interested in whether information is either kept or lost in a black hole, and has concluded that it has to be. In his earlier research he concluded that the only information which a black hole retains is its state of rotation and the amount of mass it retains, based on his earlier more controversial hypothesis that photons are slowly leaked from black holes do to quantum fluctuations, called Hawking Radiation, which was eventually more widely accepted due to the support of other leading physicists.
Physicists argue over if information is lost within black holes, and Stephen Hawking came to the conclusion that in order to abide by the laws of physics, information had to be preserved within a black hole. He based this statement off of the law of physics that everything can be broken down into the storage of information, for example a binary code of 1s and 0s, because this is considered a law of the universe it would stand that information can’t be destroyed even by the extreme physical powers of black holes. Though there is an information paradox with the theory of general relativity Professor Hawking believes that the information is stored inside the event horizon. This greatly contrasts Einstein’s theory of general relativity, which compared the mass of stars and other objects such as black holes to marbles of different weights pulling down on a sheet of infinitely flexible material, whereas Professor Hawking has developed a hypothesis that there is no interior of a black hole. He suggests that through a process known as super translation this crucial information is transformed into a 2-D hologram and stored in a state that in the event that it was released it would have descended into a useless chaos. Though there is hardly consensus to this possibility, it is worth noting due to its relevance.
The Event Horizon Telescope is an international project, the goal of which is to observe the event boundary. If successful, this project will combine the data from radio telescopes all over the globe, essentially turning the planet into a giant radio disk. Radio waves are being used in order to attempt to photograph the center of the Milky Way because like other forms of image transmission, they can pierce through all of the objects and galactic dust separating Earth and Sagittarius A, which are the reason that no previous attempts at similar goals have been successful. Katie Bouman is a MIT graduate, and she is the one whose algorithms and image developing technology are making this possible. She has brought together several large organizations with radio telescopes and hopes that more will join the project in order to achieve a task that she compares to, “taking the image of a grapefruit on the moon.” Using multiple telescopes to overcome atmospheric noise and a widely successful program which uses a variety of previous images, particularly those of the galaxy, to enhance the data. Using these various techniques, programs, and theories each day progress is being made towards the first image of a black hole.
*It should be noted that the uncertainty relation (Heisenberg 1923) causes some of the contents of smaller black holes to move faster than the speed of light, causing one of the fluctuations which allow for some particles to escape as stated in the theory of Hawking Radiation. This would also cause smaller black holes to leak particles at a faster rate and therefore deteriorate faster.
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