Okay, there’s this story about a blackhole that is “hurtling” towards our general area.
I don’t get it.
Actually, I don’t get it to the point where I’m not sure how to ask my question… “Spawned a black hole?” Black holes move? And why would it move faster than its neighbours?
I thought when stars went supernova, it was kind of like an explosion so everything started moving outwards (sort of spherically) and then it sort of re-imploded into a teensy-weensy super-dense point. At least that’s how I’ve always pictured it in my head.
Can someone explain the “cannonball balck hole” theory to me?
It turns out that supernovae are not always symmetrical. Sometimes the blast happens more on one side of the star than the other. When that happens, the resulting neutron star/black hole is given a big kick in the opposite direction.
The whole moving black hole kind of boggles my mind – being so massive, I never actually conceptualized them moving at all except for continuing roughly along the original path of the star.
I can visualize that off-centered kaboom though.
So is this thing totally interfering with the motions of other bodies out there or is there enough distance between stars and major celestial bodies that it won’t cause that many problems? (I’m picturing a giant Pac Man gobbling up everything in its path.)
It shouldn’t disrupt any other stars, unless by chance it happens to run directly into one. Just coming close will not result in the other star being gobbled up, although depending on how close it came, it might disrupt the orbits of any planets. But the odds against even coming that close to another star are literally astronomical since there is lots and lots of space between stellar systems.
It seems to be a common misconception that black holes have some kind of magical infinite gravity, whereby they can suck up anything around them, however distant. In fact, the gravity of a black hole is no different than that of any other body of equivalent mass.
November’s Scientific American did an article on collisions between stars, black holes and neutron stars; the chances of such a collision are minute in an area of the galaxy such as ours, but significant closer to the galactic center and in globular clusters. A black hole hitting the sun would be as bad news for us as if it had directly hit the earth.
I once saw an article in Family Weekly which stated that black holes would start drawing other matter in space toward them; it ended, “Eventually black holes will swallow the universe.” Now that’s a disturbing thought.
Actually, it is thought that all black holes will eventually evaporate through Hawking radiation and the universe will die an entropy death in which all matter has decayed to elementary particles swimming ina random soup at a temperature approaching asymptotically to absolute 0. Does that console you. Of course that won’t happen for quite some time yet, something like 10^120 years.
dougie_monty, please tell me you’re kidding with that reference.
Black holes do draw matter towards them - in exactly the same way any body in the universe attracts and is attracted by any other body - gravity. The attraction is dependent on the mass of the two bodies in question (the black hole and the other body) as well as the (square of) the distance between them, as long as you don’t get too close to the event horizon. Here’s a link from our own Bad Astronomer explaining it very well.
As to whether, in the very, very long run everything will end up getting sucked into BHs, I suspect that depends on the Hubble constant and whether the quantity of dark matter is enough to arrest the expansion of the universe and bring everything back together - I’m not sure which way cosmologists are currently leaning on that.
An interesting scenario I read of once would be that of living on a planet which is unfortunate enough to be within the event horizon of a supermassive black hole. Because the BH is supermassive, ‘spaghettification’/tidal forces wouldn’t be such a problem, so presumably if it were massive enough we could be living inside the EH. Imagine that - seeing a patch of sky that you are being inexorably being drawn towards, knowing that that singularity is in your future. <Shiver>
You seem to have a pretty good understanding of how this all works, but I believe (geez, I’ve had this in enough classes; I should know by now) that this is not totally accurate even for a spherically symmetric supernova. The core collapses (or implodes, if you like) into a neutron star or black hole, but the ejected envelope does not fall back onto it; it escapes.
Don’t worry. We’ve got like 10[sup]80[/sup] years to figure out how to violate the fundamental laws of thermodynamics. I’m sure we’ll be able to throw something together in that amount of time.
>>I suspect that depends on the Hubble constant and whether the quantity of dark matter is enough to arrest the expansion of the universe and bring everything back together - I’m not sure which way cosmologists are currently leaning on that.
I read, not in Family Weekly, that it is “looking” like there is enough matter. Sorry no cite. I believe it was from an astrophysics text book.
Jeez, Bob, what the hell have we been doing for the last 10[sup]79[/sup] years? We’ve got to solve this entropy death thing, and stat! Looks like it’ll be an all-nighter.
To Hari, Darren and others: I think this is my point. I get the same meaning–the same as what Hawking has expressed–from fundamentalists who claim that some day in the distant future the earth will be burned up. (Compare Psalm 37:11. Not that getting sucked into a black hole, or losing the sun’s energy and being in total darkness, or undergoing “entropy death” will be any more comforting,. )
Throughout this thread everyone has talked about massive blackholes. My understanding (which I cheerfully admit isn’t all that good) is that black holes do not need to be all that massive. In fact any mass at will do nicely, thank you. It just has to be compressed enough that the excape velocity requred is greater than the speed of light. I suspect that the BHs with small mass aren’t all that common because of the difficulity of attaining enough force to get the needed compression. Gravity decreases in force inversely as the square of the distance between two objects, and the reverse is true as you get closer.
Isaac Asimov wrote a great short story titled, “The Last Question,” based on the quote above. Check it out, literally, most libraries should have it.
Here’s a question. Is life possible in a Black Hole?
Except for the fact that a black hole with the mass of the Universe would be about three billion light years across, more if the “missing mass” is in fact there and just not observable. In essence, the inside of such a black hole would very closely resemble the Universe that we live in.
Now that’s a disturbing thought.