There are few things in the entire Universe that are as terrifyingly awesome as a black hole. To have a region of space exist that contains gravitational forces so strong that literally nothing can escape it (whether it’s a particle, light, or any electromagnetic radiation for that matter) seems like a concept straight out of a sci-fi novel or scary space movie. The general idea is that a ton of matter is compressed and compacted into such a small space, generating a gravitational field that nothing can escape from it.
These regions of spacetime, known commonly as black holes, were first theorized back in the early 1900s based on Einstein’s theory of general relativity. In essence, his explanation demonstrates two important principles (listed below):
- Moving things follow curves in space (which are created by mass).
- Light travels at a constant speed, but it is affected gravity (meaning that if light changes speed, it’s traveling along a curve in spacetime).
From these two fundamental ideas behind general relativity, physicists and astronomers were able to conjecture that black holes can exist (Schwarzschild). With that in mind, they were also able to conclude that when massive stars die (as a result of running out of nuclear fuel), they leave behind small yet super dense cores. Depending on the composition of that core (whether or not it has enough mass), gravitational forces can overwhelm everything else acting on the core, producing a black hole.
What’s even crazier than the idea of a black hole is the fact that humans currently can’t even directly observe black holes (with any sort of telescope, no matter the type of electromagnetic radiation it looks for). Because black holes are inherently empty space, there’s “nothing” to actually observe. Instead, we’re able to determine the presence of black holes by monitoring their effects on space objects nearby. By looking at the effects that black holes have on different celestial objects (whether it’s interstellar matter, stars, etc.), physicists are able to make conclusions about black holes’ behavior and thereby learn more about them. More information can be found at the following link.
And lastly, it’d be remiss to not mention the recent photograph scientists were able to take of a black hole. Using the Event Horizon Telescope, scientists were able to image the supermassive black hole at the center of galaxy M87. The actual picture taken can be seen below!