By DiMarkco Chandler:
The average layman is usually confused when it comes to understanding Black Holes. Most believe that once an object is captured by these collapsed stars that it’s impossible for them to escape. While this is presently true on a macroscopic scale, theoretical physicist Edward Witten is challenging its microscopic probability. In order to grasp Witten’s claim, it’s important to have a comprehensive and unambiguous sense of what Black Holes are.
For one thing a Black Hole isn’t really a hole – it is an object that is so highly compressed that its escape velocity exceeds the speed of light. What this means in layman’s terms is that nothing can escape or perhaps more specifically, nothing can escape its gravitational pull.
A clearer understanding of this idea might be best expressed by our common understanding of earth’s gravitational pull. No object can escape beyond Earth’s gravitational field unless the speed of that object exceeds Earth’s escape velocity. For instance, if NASA launches a rocket that is unable to reach Earth’s escape velocity, measured in terms of speed, it will fall back to Earth. Thus, Black Holes are best understood in terms of their escape velocity.
The escape velocity from the surface of an astronomical object depends on the strength of the gravitational field of the object’s surface. If you want to know the formula for calculating escape velocity you need to know the object’s total mass and radius. Black Holes are formed when a star collapse to a smaller size while keeping the same mass. Since the consequence of collapse gives the star a higher density, its escape velocity increases. Once a star collapses to an extreme degree, the escape velocity from the surface eventually reaches the speed of light. At this point, the star becomes a black hole.
According to Einstein’s special relativity theory, the speed of light is the ultimate speed limit in the universe. Nothing can travel faster than the speed of light. Light is by definition massless and therefore travels at light speed. Any particle or object having mass can travel close to, but never reach or exceed the speed of light. Hence when a star collapses to the point that its escape velocity exceeds the speed of light, nothing can escape? Wrong; nothing can escape its surface.
A black hole is therefore simply a star, or other object, that has collapsed to the point where its escape velocity exceeds the speed of light. Nothing, not even light, can escape from a black hole. Anything that falls into a black hole is in theory trapped forever.
However, Edward Witten says; not so fast. The stated fact that nothing can escape from a Black Hole has led to a very common misunderstanding of them. My argument here attempts sets the record straight, and reiterate that nothing can escape its surface. In other words, an object has to be close enough to be impacted by its gravitational pull; any object at a distance is protected by its own gravitational pull that tugs in the opposite direction.
Nevertheless, Witten has moved beyond this theory or should I say, he is attempting to disprove it by demonstrating the theory’s incompatibility with the theory of quantum mechanics.
Witten argues that the basic theory, which suggest nothing can escape a Black Hole, contradict the laws of quantum mechanics, governing the universe’s tiniest elements.
“What you get from classical general relativity, and also what everyone understands about a black hole, is that it can absorb anything that comes near, but it can’t emit anything. But quantum mechanics doesn’t allow such an object to exist,” Witten said in this week’s Science podcast.
In quantum mechanics, if a reaction is possible, the opposite reaction is also possible, Witten explained. Processes should be reversible. Thus, if a person can be swallowed by a black hole to create a slightly heavier black hole, a heavy black hole should be able to spit out a person and become a slightly lighter black hole. Yet nothing is supposed to escape from black holes.
To solve the dilemma, physicists looked to the idea of entropy, a measurement of disorder or randomness. The laws of thermodynamics state that in the macroscopic world, it’s impossible to reduce the entropy of the universe — it can only increase. If a person were to fall into a black hole, entropy would increase. If the person were to pop back out of it, the universal entropy tally would go down. For the same reason, water can spill out of a cup onto the floor, but it won’t flow from the floor into a cup.
This principle seems to explain why the process of matter falling into a black hole cannot be reversed, yet it only applies on a macroscopic level.
Physicist Stephen Hawking famously realized that on the microscopic, quantum mechanical level, things can escape from black holes. He predicted that black holes will spontaneously emit particles in a process he dubbed Hawking radiation. Thus, quantum mechanics refuted one of the basic tenets of black holes: that nothing can escape.
“Although a black hole will never emit an astronaut or a table or a chair, in practice, it can definitely emit an ordinary elementary particle or an atom,” Witten explained.
However, scientists have yet to observe Hawking radiation.
“Unfortunately, the usual astrophysical black holes, formed from stellar collapse or in the centers of galaxies, are much too big and too far away for their microscopic details to be relevant,” Witten wrote.
It would seem that relativity could play a major role in the future of our understanding of Black Holes and how they function. Perhaps, macro object and micro objects could interchange in terms of their category relative to the observer of these elements. Just a thought.