Black holes are essentially places where the rules of spacetime break down, and as such they are extremely intriguing. This article explains black holes in a way that is easily understandable to the general public. Find out how black holes got their name, how they form, and what might possibly be happening beyond their event horizons.
The cosmic objects known as black holes are one of those scientific findings that have captured the popular imagination. A black hole isn’t technically an object, but rather the name given to the region of spacetime around an extremely massive object. Black holes are very intriguing, and even a little scary!
How They Got Their Name
The best way to understand what black holes are is to take a close look at their very descriptive name, as they are quite literally “black holes.”
The “black” part of the name was given to these stellar anomalies because they are so massive that no light can escape them. It has since been found that black holes do indeed emit a small amount of radiation (dubbed “Hawking radiation”), but this radiation is very weak and impossible to detect, at least with our current and foreseeable technology.
The “hole” part of the name comes from the fact that these objects act like holes in observable spacetime. Any matter that goes into a black hole effectively “falls” down the hole and cannot be observed from the other side anymore.
The point at which any object or any information can no longer be observed after falling into a black hole is called the event horizon. This is the exact point at which the escape velocity (the speed at which an object would have to travel to escape) exceeds the speed of light. According to relativity, nothing can go faster than the speed of light, and so once something falls past the event horizon of a black hole, it can never escape.
How Big Is A Black Hole?
So how big, exactly, is a black hole? When speaking about the size of a black hole, scientists refer specifically to the radius of its event horizon, which is commonly called the Schwarzschild radius. The Schwarzschild radius depends only on one factor – on how massive the object was before it became a black hole. To give you some perspective, a black hole that formed from an object the mass of our sun would have a Schwarzschild radius of 3 km.
Black Hole Formation. Event Horizon.
Black holes are formed when a star collapses to the point where it is smaller than its own Schwarzschild radius. Since light cannot escape the event horizon, the star essentially vanishes. Though the star may visually disappear, its mass remains exactly the same and continues to exert the same amount of gravitational force.
Since the event horizon creates a barrier between the inside of a black hole and the observable universe, we have no real way of knowing what exactly happens to the matter that falls in. Based on the laws of physics, however, it is possible to infer that it gets crushed into an infinitely dense and infinitely small point known as a singularity.
While the idea of a singularity is mind-boggling enough, recent decades have seen certain scientists propose that black holes may in fact lead to other universes. This idea has grown out of quantum mechanics and the multiverse theory.
Whatever it is that really takes place beyond the event horizon, black holes are certain to remain at the forefront of scientific research about the nature of the cosmos. Everyone, scientist and non-scientist alike, will continue to be captivated as new findings come out about these “massive” mysteries.