If a black hole is hurtling towards Earth and we have 120 years until impact, what can we do that is
The typical answers seem to be either 1) deflect the black hole, or 2) they’re too massive to deflect, so just prepare to die. Some of the answers are well grounded scientifically, and some are just opinion. One was just an ideological rant against conservatives.
If a black hole is large enough to detect 120 years prior to intersection, it is really really big. We would have to discover it by its damage trail, which means it is killing stars triggering novae. After a kill the accretion disk would taper off in brightness quickly, so we wouldn’t see it directly most of the time. So let’s say it killed a star 30 light years away and had a calculated velocity of 1/4 light speed. That’s a really really big black hole moving really really fast.
UPDATE: Oops! Make that 1/5 light speed. It’ll take 150 years to get here, but we won’t know about its latest victim until 30 years after it happens, and only then if it triggers a nova or if a lucky astronomer notices a black hole burp (jet) and nothing else where a star used to be. Upon reviewing my math, a speed of .2c is wack, being almost 5 times the speed of the fastest known stellar mass object in our galaxy. So make it a starkill event 11Ly away, and travelling at the still whopping speed of 0.08c (roughly 50 million miles per hour compared to light’s speed of 670 million mph. That’s 11 years to observe, then another 120 or 130 years to anticipate our horrible tragic death.
Okay, can we apply reason just a little bit? You’re NOT going to deflect something bigger than a billion mountains with something less than a few earth-sized objects in mass. What are we going to do? Throw Jupiter at it?
Alternatively, we’re not going to just plan on dying on Guy Fawkes Day, 2207. It might happen anyway, but until it happens, we’ll keep on trying to find a way to survive it. And THAT is the question. What could we _theoretically_ do to survive. I have three theories.
First, assuming the killer black hole is passing through our solar system, but not hitting anything critical like, oh, the SUN, but is on a collision course with Earth, the answer is…don’t be there. If someone told you that in an hour a bullet would be passing through the spot where your head is while you do your normal daily routine, you would change your routine! Moving the Earth is no small task, of course, but given time, it may be possible. An increase of perhaps .1% of orbital speed (angular velocity?) would put Earth in a very different spot in 30 years or so. Might even be a small enough change to keep Earth inhabitable while it’s happening.
Second, move out of the Solar System. Just the people. Figure out nonlinear travel (moving from point A to point B without going through every point in between). Maybe only one in a million could be saved, but that’s enough for the continuation of the human race. Bye, Earth. We’ll miss you.
Third, what are we? Most of us reading this today will be dead in 120 years. So “we” must refer to humanity, right? What is humanity? A bunch of brains walking around in meat suits. Find a way to store minds in flash drives, put ’em on a Voyager-type ship with robotic…uh…chip readers than can put those flash drives into new bodies, or some replacement for meat suits. Sounds like a sucky meaningless existence, but it beats no existence.
And for dessert, a seriously outrageous suggestion. The mass of black holes is so immense that time itself slows to a slow crawl around it. Maybe we could figure out how to jump into a black hole without getting “spaghettified” (it’s a real word. look it up!) and a few million years later come out of it. Wouldn’t it be a hoot if we did that, and found another two dozen alien races had done the same thing? :)