The Secret World Of Black Holes - Dr Becky Smethurst

People ask me questions like, "What's on the other side of a black hole?" Which doesn't make any sense when you realize that black holes aren't holes. They are 3D objects that were once stars that have just been crushed down until they are so, so dense that the gravity is so strong that nothing can escape from them anymore, not even light. (wind blows)

What is your problem with the name black holes?

(laughs) This is the thing. This is something I've spent my entire life, like, trying to understand, and yet I hate the name for them. I hate it so much. I don't think there's any other words in physics that have caused more misconceptions than black holes, because they are neither black nor are they holes. (laughs) Black holes. And this is, this is what bugs me about them. So, you know, people picture a black hole as this physical hole in space that stuff is, like, lost down. You know, people ask me questions like, "What's on the other side of a black hole?" Which doesn't make any sense when you realize that black holes aren't holes. They are 3D objects that were once stars that have just been crushed down until they are so, so dense that the gravity is so strong that nothing can escape it, from them anymore, not even light. They're almost like prisons for light, and I often say that a better name for them was probably dark star, but even that's not, not perfect either. So, it, I mean, I'm sure a lot of listeners could probably come up with their own (laughs) better names for them, but black hole especially is one that just, if I could go back and be like, "No, let's not call it that," back to the sort of '60s and '70s, I would. (laughs)

Who was the guy that called them black holes? What was the story with him?

Yeah. So it comes from a, a bit of a harrowing part of history, actually. Um, are you familiar with the Black Hole of Calcutta?

No.

No. So the Black Hole of Calcutta is a prison cell, um, in an old Fort William in Calcutta in India. And, um, there is this sort of tale from history where British soldiers were imprisoned in this prison cell, which was the size of three double beds. And there was about 70 soldiers imprisoned overnight in this one very cramped, tight space, and, uh, historians sort of claims estimate, you know, that around about 20 of them actually survived that one single night after being imprisoned in this such incredibly cramped quarters. And there was a physicist called, um, Robert Dicke in the '60s, who was studying what then were known as gravitationally completely collapsed objects, or GCCOs, which, again, is a term I'm quite glad that didn't stick. Um, and him and his family used to say that, you know, if something was lost in their house, "Oh, it's gone to the Black Hole of Calcutta." And so, he started to use this phrase, you know, in his academic talks as sort of, you know, as like, almost like brevity and advertising value essentially was how it was described by the physicist, uh, called Wheeler as well. And, uh, essentially, he compared the crush of matter down to the, the crush of these soldiers in this prison cell as well in the Black Hole of Calcutta. And I think when people hear about the Black Hole of Calcutta, there's lots of memorials still in Calcutta in India today, they think that the prison got its name from the astronomical object, but in fact, it's the other way around, which I think people don't realize.