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Facts About Black Holes
The development of black hole theories is one that has taken place over a period of more than 200 years. There are several ways to look at black holes, but the simplest way of thinking of them is as a gravitational trap. The first theories recognized that there were areas of space, where light did not escape from. It took more than 100 years of science to accept that gravity could affect an electromagnetic wave like light. But, it was proven that light did not escape these gravity traps. Black holes also created some special language in relativistic physics and astrophysics. As the technology of observation evolved, scientists could see the effects of light passing near a large massive object, be it a black hole or a galaxy cluster, as it distorted the light coming from objects even more distant in what is known as gravitational lensing. This is light distortion, not actual light dropping into the black hole.
Today our Hubble telescope can indirectly identify a black hole by the effects on the motion of nearby stars, or the high energy x-rays emitted. We rely on this indirect evidence that black holes exist.
Black holes have mass, charge and angular momentum and a charge like an atomic mass.
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Theories About Black Holes
One of the most recent theories is that a black hole is a “deformation of spacetime" caused by a gravitational force in a region of space generated by a compact mass. Theoretically, a mass is so dense that it creates a gravitational trap that nothing can escape from. The theoretical mass of a black hole has never actually been observed. Gases appearing to superheat while falling into a black hole have been proven to be real. This has brought about a new term called an event horizon. The event horizon is a region around the black hole in which a mass or energy is trapped by the gravity of the black hole and cannot escape. Theoretically, this would be at the very edge of the black space surrounding the black hole.
The theoretical calculations about the masses behind these odd regions of gravity have calculated that it would take millions of solar masses to create some of these black holes. These calculations have confirmed that there is a massive black hole at the center of our Milky Way Galaxy. Scientists have also confirmed the presence of similar massive black holes at the center of other galaxies. While no theory has made a connection between galaxy centers and massive black holes, the question remains, could these black holes provide a necessary gravitational force (cold dark matter) for galaxies to form?
The fact that black holes have an event horizon creates an interesting scenario. When an object falls into a black hole, does the perspective of an observer outside of the event horizon and that of the fallen object remain the same? From the perspective of the observer, they would see the object approach the event horizon and get dimmer as it got closer to the horizon as the light from the object was more and more red shifted. The object's clock would slow down to a stop as it slowly fades from view. The object would not experience any of this but would pass through the event horizon, at which time it would begin to feel the gravitational tidal forces, which would tear it apart. Time, gravity and relativistic theories are interrelated. Einstein’s General Theory of Relativity can explain this relationship more fully.
There is much more to learn about black holes and the relationship between gravity, light and compact solar masses. Most of what we accept as true is actually theory. We will learn much more when we can travel to the event horizon of a black hole.
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