A black hole is not only one of the most powerful and dangerous regions in space, it is also one of the most mysterious. Think about it—even though physicists like Einstein predicted that they existed almost 100 years ago, we only just got an actual photo of one in 2019!
The key to all of this mystery is that nothing—not even light—is fast enough to escape a black hole. Once something is inside a black hole, it's there forever. In addition, once something crosses the border of a black hole—also known as the event horizon—a process known as spaghettification would begin. Essentially, whatever passed this border would be stretched and pulled apart by the atoms until it was ripped apart.
Yikes. Sounds like a good reason to stay away if you ask us!
But, what if you could go inside a black hole and study it? In fact, what if you actually can?
Entering the unknown
That was a question asked by Pulkeet, a 12-year-old from Bahadurgarh, Haryana, India. She submitted it to a really neat website called Curious Kids, and her question was answered by a pair of physicists—Leo and Shanshan Rodriguez—from Grinnell College in Iowa. Their answer?
In short, if the conditions were right, a human likely could enter a black hole and study it. The only thing? That person would never be able to leave. And neither would any of the data that they found. But the fact that a person could safely enter a black hole was news to us!
So let's look at why these experts think it would be possible.
The right type of black hole
First off, a human couldn't fly up to just any black hole and expect to safely get inside. For one, it would need to be an isolated black hole without anything nearby. Why? Because black holes just love to suck up matter around them and create a huge swirling cloud known as an accretion disk. The matter in this disk is moving at a high speed and is super hot—much like the plasma in a star. So your chances of getting through that are basically zero!
Next, the black hole could not be a stellar mass, or smaller, black hole. To be able to enter the black hole, it would instead need to be a supermassive black hole—one with a mass of over a million Suns. Funny. That seems backwards. Why is the far more powerful black hole the safe one to enter?
The reason has to do with how far from the centre—or singularity—of the black hole you would be when you passed the event horizon. Remember, this is the border of the black hole.
In a stellar mass black hole, the event horizon might only be a couple miles from its centre. A couple miles might feel kind of far on Earth, but when you're dealing with a gravitational force that is black-hole strong, it's super close. And it would be getting stronger with every 'step' you took toward it. Say you reached your arm out toward the centre. The pull on you fingertips would be hundreds of billions of times more powerful than it would be on the rest of your body. That would be too much for the body to take!
And so it would be spaghetti time!
Getting some distance
But what about that supermassive black hole? Overall, it is much, much, much more powerful than a stellar mass black hole. These are the black holes that power ENTIRE GALAXIES! And yet ...
The distance between its event horizon and its centre is absolutely huge—several billions of miles. (And that's just with the 'small' supermassive black holes!) So when you crossed its event horizon, each step would not give you the same kind of huge increase in gravity. Instead, the force would remain about the same as you drifted forward—spaghettification would not occur. Now you could pass into the black hole ... and see what was inside.
Again, keep in mind: once inside the event horizon, you could never leave. And everything that you saw? You'd never be able to send a message about it to anyone.
But would you survive getting in there? If the conditions were absolutely right, the answer seems to be yes!