UnNews:Impossible black hole explained
| We have met the enemy, and he is us | ✪ | UnNews | ✪ | Friday, April 19, 2024, 04:22:59 (UTC) |
| Impossible black hole explained | 
|
3 September 2020
Los Angeles, California USA -- In a pleasant change from the colliding cultures of earthly politics, Professor Elmira Squint has announced the detection of two black holes merging earlier this year. Black holes apparently do this sort of thing but they stay out of sight as they are, well, black and very hard to see against the equally black space that they inhabit. Professor Squint has kindly consented to explain this fascinating bit of astrophysics to our readers.
UnNews: "Good evening, Professor Squint. Our thanks for your generous offer to fill us in on this amazing discovery."
Prof. Squint: "My pleasure, although it is actually 2:00 am in the morning here."
UnNews: "Oh, sorry. Forgot to look at World Clock before I rang. Now earlier this year you detected this collision of black holes. How far away was it?"
Prof. Squint: "Around 6.62 times 10 to the 21 kilometers, plus or minus a few billion."
UnNews: "Wow. that must have been pretty hard to see."
Prof. Squint: "Well, we didn't actually see it, we sort of felt it. You know how when there's an earth quake, you can feel the earth move? We have instruments that can detect very tiny little disturbances in the gravitational field. That's how we noticed it had happened."
UnNews: "So that's why nobody really noticed it this past May."
Prof. Squint: "It happened about seven billion years ago."
UnNews: "So how come it took us this long to notice it?"
Prof. Squint: "As I said, it's a long way from here and it takes that long for the gravitational waves to get here."
UnNews: "Right. Now in your paper you mentioned that one of these black holes was impossible. If it was impossible, how did it get there to meet the other black hole that we assume must have been possible?"
Prof. Squint: "We thought it was impossible in the sense that black holes form from the collapse of very big stars and the bigger black hole was more massive than the biggest star that we thought could exist."
UnNews: "Okay. But if these two black holes merged, the resulting black hole must have been even more massive."
Prof. Squint: "You've got it. Two smaller black holes must have merged to make the bigger black hole before it merged with the smaller black hole."
UnNews: "But you didn't notice that merger."
Prof. Squint: "There are a lot of black holes out there. We can't keep track of all of them at the moment. Besides, that merger might have happened millions of years before the one we noticed and the gravitational waves would have passed by while our ancestors were still writhing around in the primeval slime. Happens all the time, you know. Ooooh."
UnNews: "I see. Let's get on to the important question of how these black holes met."
Prof. Squint: "For that question I must refer you to my colleague Prunella Ponder, Professor of Astrophysical Sociology."
UnNews: "Won't Professor Ponder be in bed?"
Prof. Squint: "Not at all, we're just having a little party here in the staff room. Over to you Pruney. Oops."
Prof. Ponder: "Ouch. I'll get a bruise there, Ellie. Hi. You wanted to know how black holes meet?"
UnNews: "Uh, yeah, I guess so."
Prof. Ponder: "The current thinking on black hole social interactions is that they are quite similar to those observed in humans. You know, as below, so above. Space is a very big place and while black holes are just as keen to get together as we are there may not be a lot of other black holes nearby. So they have to wander around in space trying to find a Little Bang."
UnNews: "A Little Bang? Is that like the Big Bang?"
Prof. Ponder: "Yes, except a lot smaller and you don't get a universe. Just like us, they move around looking for Little Bangs. I think it's awfully romantic."
UnNews: "So all these black holes are cruising around space looking for each other. But if they're all black, how do they find each other?"
Prof. Ponder: "Gravity. Black holes have a lot of gravity. Think of it like an aura. When we pass by someone here on earth, we can kind of sense that person's aura. When two black holes get near each other, each one can tell how much gravity the other one has got. If there is enough gravity, they are irresistably drawn to one another. I often imagine them spiraling around each other until BANG, they become one."
UnNews: "So if these black holes are merging all the time, this must mean that the black holes are getting bigger and fewer."
Prof. Ponder: "So they are. You probably want to talk to the Professor of Astrophysical Economics, Krakotoly Akountovitch. Here you go, Krak."
Prof. Akountovitch: "Thanks, Pruney, just roll over for a minute, so I can talk properly. So you want to know about black hole mergers, eh? The simple dumb head model is that eventually, yeah, you get a monoholey. We can see it in the really big black holes at the middle of galaxies that have been sucking in stuff for ages. Because they are all trying to corner the gravity market, they compete for mass. This is good for the local monoholey with its economy of scale, but all the stuff that gets sucked in is not too happy about it. The more stuff you have inside, the harder it is to keep it in. Fortunately the increase in gravity has been enough to keep it in so far. But if you do get a monoholey of the whole universe, you face the situation of an infinite supply of gravity with no demand."
UnNews: "What happens then? Is that the Impossible Black Hole?"
Prof. Akountovitch: "Ah, you're really talking Astrophysical Philosophy there. Professor Oliver Omphalocentrum is the one you want. Ollie, can I have Pruney back again? Thanks."
Professor Omphalocentrum: "I'll try to make this brief Krak, looks like Ellie is free. When black holes merge, we have the identity problem. In the present case, GW190521 is neither of the two black holes that merged. No way we can get them back again, for all of their identifying features, which sum to how big they were, have vanished unless we can find reverse gear in time. So at some point, we can imagine all of the identities disappearing into one big identity. Since everything is in it, there is no way to verify that identity because there is nothing to observe it. So, if a black hole manages to become the only black hole and no one is there to observe it, is it still a black hole or does it perish from lack of attention? Does that answer your question?"
UnNews: "In a way. I suppose we should let all you professors get back to your party and thanks for all the interesting information about black holes."
Professor Omphalocentrum: "No worries. Hey, Ellie..."
Sources[edit]
- Genelle Weule "'Impossible' black hole causes biggest collision ever detected by gravitational waves". ABC News, September 3 2020