Sorry science fiction lovers. In fact, you cannot survive the journey through a black hole. And if you try to dive into one of them, like Matthew McConaughey in the movie Interstellar, you will be torn apart long before you know what is on the other side.
Well, if it is more detailed, then …
What is a black hole?
To fully understand why you can't just dive a swan or pilot your spaceship into a black hole, you must first understand the basic properties of these gravitational Goliaths. Simply put, a black hole is a place where gravity is so strong that no light - or anything else, for that matter - can escape.
Black holes are so named because they usually do not reflect or emit light. They are only visible when they feed on stars or gas clouds that come too close to their boundary, called the event horizon. Beyond the event horizon is a truly tiny point called the singularity, where gravity is so strong that it infinitely bends spacetime itself. This is where the laws of physics, as we know them, break down, which means that all theories about what lies outside of them are just speculation.
Black holes seem exotic to most of us, but they are common to scientists. Physicists played with theories of similar objects for decades before Albert Einstein's general theory of relativity predicted their existence. However, this concept was not taken seriously until the 1960s, when extremely compact stars were discovered. Today, black holes are considered a common part of stellar evolution, and astronomers suspect that there are millions of black holes in our own Milky Way galaxy alone.
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Choose your own black hole adventure
Black holes come in different types and can be modeled with different levels of difficulty, for example, regardless of whether they are spinning or have an electrical charge. Therefore, if you jump into one of them, your exact fate may depend on which black hole you choose.
At the simplest level, there are three types of black holes: stellar mass black holes, supermassive black holes, and medium mass black holes.
Stellar mass black holes form when very large stars finish burning their fuel and collapse inward. Supermassive black holes live at the centers of most galaxies and are likely to grow to their extreme sizes - up to tens of billions of times more massive than our Sun - by swallowing stars and merging with other black holes. Medium-mass black holes are still mysterious and only a few alleged examples have been discovered, but astronomers believe they could form from a similar accretion process, only on a smaller scale.
Stellar mass black holes may be paltry compared to their larger cousins, but in fact they boast more extreme tidal forces just beyond the event horizon. This difference is due to a property of black holes that would probably surprise some casual observers. Smaller black holes actually have a sharper gravitational gradient than supermassive ones. In other words, you only need to fall a very short distance to experience an extremely noticeable difference in gravity.
Black hole spaghetti
If you floated freely in space next to a stellar mass black hole that was not feeding on anything, then the only hint of its existence could be the gravitational increase, or "lensing" that it could exert on background stars.
But as you flew closer to this strange place, you were pulled in some directions and crushed in others - a process that scientists call spaghettification. This is because the gravity of the black hole squeezes your body horizontally, while simultaneously pulling it like a taffy vertically. If you jumped feet first into a black hole, the gravitational force on your toes would be much stronger than the force pulling your head. Each piece of your body will also be pulled in a slightly different direction. You would literally look like a piece of spaghetti.
So when you fall into a stellar mass black hole, you probably won't be much worried about the existential secrets you might discover on the “other side.” You will be dead like a spaghetti-shaped door nail hundreds of miles before how you reach the singularity.
And this scenario is also not entirely based on theory and assumptions. Astronomers witnessed this "tidal disruption" back in 2014, when several space telescopes caught a star wandering too close to a black hole. The star was stretched and torn apart, causing some of the material to fall off the event horizon, while the rest was thrown back into space.
Step carefully into this black hole
Unlike falling into a stellar mass black hole, your experience of falling into a supermassive or intermediate black hole will be a little less nightmarish. While the end result, a gruesome death, will still be your destiny, you can actually go all the way to the event horizon and start falling into the singularity while you are still alive.
In this case, at least in theory, you could see the surrounding space. But no one will be able to see you once you go beyond the event horizon. Even if you held a flashlight in your hand and tried to shine it, the light would fall back into the singularity with you.
Meanwhile, you'll see that everything within the event horizon has been distorted by extreme gravitational forces, thanks to an effect astronomers call gravitational lensing. (Not to mention the wild time dilation effects.)
Of course, no matter which black hole you end up in, you will ultimately be torn apart by extreme gravity. No material, especially fleshy human bodies, could survive intact. Therefore, once you pass the edge of the event horizon, you are done. You can't get out of here. Even if you were still alive, you would have to move faster than the speed of light to be saved. But as we know, nothing in the known universe can do this.
But don't worry just yet: the closest known black hole to Earth is still a daunting thousand light-years away. However, astronomers suspect there are many more lurking much closer, perhaps just a few dozen light-years from Earth. In fact, some researchers believe that the hypothetical Ninth Planet of the distant solar system is actually a primordial black hole about the size of a baseball.
With this in mind, it is entirely possible (though unlikely) that if humans survive long enough to become the pioneers of advanced space travel technologies, we might be able to visit a black hole up close. And if we do that, we may even launch several probes into the black hole to check what is happening on the event horizon.
Unfortunately, since nothing can escape the event horizon, not even information, we can never know for sure what happens when matter reaches the point of no return. So even if you have the opportunity to make a cosmic dive into a black hole, for safety reasons you should probably resist this urge.