Journeyman

I can't remember what kind of laws they've listed for things past the event horizon, but I think there's something on there about no information getting leaked.

So, if I have a black hole (very large one) at a location in space, and then throw, say, a neutron star at it from the left, then once the neutron stars last bit is within the event horizon, it should leave no trace at all. But, since there is a distance between the event horizon and the singularity, that star still travels fromt EH to S before being gobbled up.

What I'm saying is this: Wouldn't the mass of the neutron star pull the black hole in it's direction while the star is inside of the EH, changing the BH's velocity and thus leaving a trace of itself?

Giltwist

I believe the neutron star's gravity is insignificant in comparison to the black hole. THe neutron star bends spacetime, but the singularity rips it a new one.

shred_head

I'd imagine that the neutron star would go into an orbit around the black hole and that the black hole would slowly pull material off the neutron star. So this would mean that the neutron star would be all around the black hole so the overall effect would keep the black hole virtually in the same place. Though it would depend on the ratio of the masses between the two objects. However, I'm not sure how a neutron star would react to itselt being pulled apart since its just degenerate neutrons.

Even if the black hole's velocity changed there would still be no information left over about the neutron star. You wouldn't be able to tell what caused the black hole's velocity to change.

I'm quite possibly just blowing a lot of smoke and making no real sense and/or just being completely wrong. Either way, its still interesting stuff.

__________________
"Great spirits have always encountered violent opposition from mediocre minds" -- Albert Einstein

"A clear indication of women's superiority over man is their refusal to play air guitar." --Frank Zappa

shakran

The neutron star pulls the black hole toward it all the time until it reaches the center of the black hole - the same way every object in the universe pulls every other object toward it. The moon is pulling the earth toward it. You are pulling the earth toward you. Only thing is, we don't notice because the earth is so much larger that you have a negligible effect on it while it has a very noticible effect on you.

As for going into orbit, it all depends on its initial trajectory. If the neutron star were heading straight for the black hole, it'd just fall in. It'd have to be heading toward the black hole at an angle at just the right speed to go into an orbit - too fast or too wide of an angle and it'll race off into space. Too narrow and it'll get pulled in by the black hole.

locoslomo

Assuming the neutron star was heading straight at the blackhole, would the "noodle" effect happen inside or outside of the EH...i.e. would the star break apart before reaching the EH?

shred_head

No I don't think it would. The star wouldn't feel anything as it passed over the event horizon. Not until it becomes close enough to the singularity would it start to become stretched and break apart. However, if it was in abort around the black hole the tidal forces it might tear it apart before it even reached the event horizon, just like comet Shoemaker-Levy 9 did before it struck Jupiter (though that didn't involve a particularly large event horizon).

__________________
"Great spirits have always encountered violent opposition from mediocre minds" -- Albert Einstein

"A clear indication of women's superiority over man is their refusal to play air guitar." --Frank Zappa

shakran

it may not even happen until (relatively) long after it crosses the EH. It depends on the rate of increase of gravity. It has to be a high rate before there's enough gravity on the leading edge to stretch the object.

stingc

Your reasoning has two problems. First of all, a black hole does not exist at a point, so its trajectory isn't even definable on small scales. Second, the event horizon is not a fixed surface around a point singularity. This is true only for an isolated static black hole. Anything with a neutron star crashing into it certainly doesn't fit that description. An event horizon technically isn't even definable without knowing the future, so it isn't a very useful concept in this sort of situation.

rsl12

1st point: black holes CAN move. the evidence is all about the universe--there are plenty of binary systems (solar systems w/ 2 stars) where one star has collapsed into a black hole and both the black hole and the visible star are wheeling around each other.

2nd point. when the two stars (visible/black hole) are wheeling around each other, it's possible to determine the "mass" of the black hole based on the orbits of the two. i don't think this can really be called information "escaping" from the black hole--if that's considered information, then the emission of x-rays from the black hole would have to be considered some kind of information as well. similarly, even if an indestructible neutron star were to hit the black hole and cause it to bobble, i don't think that would be considered information being leaked.

3rd point. from our point of view, watching this indestructible neutron star, as the star approaches the event horizon, it will appear to move slower and slower, due to special relativity. even after infinite time, it will NOT EVER appear cross the event horizon. so the point is moot.

__________________
oh baby oh baby, i like gravy.

Sapper

Where is Stephen Hawking when you need him?

[edit: typo]

__________________
rm -f /bin/laden