Brain Teasers
Black Holes
Black holes can "eat" each other. A scientist, in an effort to destroy all but the biggest black hole, sends them all traveling toward each other. However, at the last moment he aborts this process. Why?
Answer
The black holes wouldn't destroy one another, but instead fuse together, making a bigger hole. Since Stephen Hawking states that the surface area of the final hole is bigger than the surface area of the two original holes, he would end up making a monster black hole, capable of destroying entire galaxies.Hide Answer Show Answer
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Comments
Oct 23, 2002
Awesome teaser.
Why are you so amazing??
I CANT BELIEVE I GOT IT
theoretically a large mass of 'Black Hole' could not merge, as the extreme gravity pull experienced around the 'Black Hole' is due to the indescribably small, and dense singularity at the centre. Simple maths can dectate that the mass to density ratio will be effected and so in the gravitional force of the 'Black Hole' would decrease immensly.
But totally original, and i am just stressing a point because my brother got the right answer! lol
But totally original, and i am just stressing a point because my brother got the right answer! lol
I like that teaser.I got it right beacause i actually just finished a report on black holes, but how could the scientist move the black holes even if he didn't abort his mission?
Good teaser! Black holes are a very perplexing topic. But, not too hard. Keep up the good work.
Very interesting. Got me thinking....maybe I need to learn more about black holes, as they are fascinating realy
That's scary...
There's a Super black hole heading for us right now...
Also an asteroid, the size of the moon...
There's a Super black hole heading for us right now...
Also an asteroid, the size of the moon...
I guess it wouldn't have hurt for the scientist to realize that a little earlier...?? Great teaser anyways, and very interesting!
nice!!!! but a monster black hole is scary. instant death from being torn apart. well, enjoy your last best moments of being a non- spaghetti
Fun, fun riddle. Totally valid answer.
But a couple of other things our scientist might want to consider:
On the one hand...
The universal aggregate black hole radius (being proportional to the aggregate mass) stays constant. So, like you said, he's increasing the surface area (4 pi r^2). But he's not changing the cross-sectional area (2 pi r). I think the latter figure is more important when considering navigational dangers.
So what's the benefit? Well, all black holes cause tidal effects (spaghettification) in some region of space around them. But it's only for smaller black holes that this region is *outside* the event horizon. If our scientist (engineer?) puts all of the black holes in the universe together, then all of the tidally dangerous areas will be *within* the event horizon, thus reducing the amount of dangerous space. We should be able to chart a safe trajectory that passes very near the event horizon.
On the other hand...
Our scientist is vastly, horribly, massively increasing the amount of entropy in the universe. That's a lot of gravitational potential energy gone to waste, unless he's devised a means to harness it when the black holes combine.
On the third hand, maybe I shouldn't argue with a guy who's figured out how to move black holes. :-)
-J
But a couple of other things our scientist might want to consider:
On the one hand...
The universal aggregate black hole radius (being proportional to the aggregate mass) stays constant. So, like you said, he's increasing the surface area (4 pi r^2). But he's not changing the cross-sectional area (2 pi r). I think the latter figure is more important when considering navigational dangers.
So what's the benefit? Well, all black holes cause tidal effects (spaghettification) in some region of space around them. But it's only for smaller black holes that this region is *outside* the event horizon. If our scientist (engineer?) puts all of the black holes in the universe together, then all of the tidally dangerous areas will be *within* the event horizon, thus reducing the amount of dangerous space. We should be able to chart a safe trajectory that passes very near the event horizon.
On the other hand...
Our scientist is vastly, horribly, massively increasing the amount of entropy in the universe. That's a lot of gravitational potential energy gone to waste, unless he's devised a means to harness it when the black holes combine.
On the third hand, maybe I shouldn't argue with a guy who's figured out how to move black holes. :-)
-J
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