Black Hole Affects Hours In A Day?

[Eli Grey]

Can light from a black hole affect the number of hours in a day? If two black holes collided, how long would it take for them to merge, and what would happen?

 

[chrispenycate]

There is no light from a black hole (unless it is a very little one, and evaporating); that's why it's called 'black'. Light from an accretion disc around a black hole is just that, light, and can only do what electromagnetic radiation can always do, which doesn't include modifying time. The only way in which a black hole can effect either duration or the rotation of a planet (ie. daylength) is through gravity waves, and these would be more destructive in other ways - when your tidal forces are ripping apart the crust of a planet, and the atmosphere has boiled off, you don't worry too much if it's eight forty six, or forty eight.

Colliding two black holes would give you one, more massive, black hole. The region around the phenomenon is a good one to be a long way away from. How long would depend on the position of the observer - from one of the black holes it would be forever, as time would be slowed asymptotically as the distance to the event horizon.

 

[Eli Grey]

So I can't have god like creatures passing through a black hole or passing through a light that comes from that black hole?

 

[chrispenycate]

So I can't have god like creatures passing through a black hole or passing through a light that comes from that black hole?

Assuming Hawking's equations are correct, a very small black hole (fraction of a millimetre event horizon) will evaporate, and there is no way to predict the form the few thousand tons of matter would take. Logic would expect a disorganised, randomised gas or plasma - but logic wasn't expecting the thing to evaporate in the first place. Personally, I wouldn't try it too close to a planet - a lightyear or two would seem reasonable with the energy levels we're talking about. So physics can't actually contradict a godlike being materialising from an evaporating black hole, but it can say the probability is only expressible in fairly impressively small exponentials.

 

[Eli Grey]

Thanks for explaining this.

 

[chrispenycate]

Thanks for explaining this.

Any time (dilated or otherwise). Oh, was that irony? (I'm just about a dwarf and suspect irony is metallic and a bit reflective) Personally I'm quite enthusiastic about the idea that one of the micro black holes CERN is supposed to be generating over here will evaporate into the eternal Cthulhu next to the airport.

Actually, the Services Industriels won't supply enough energy for anything more than a few milligrams of black hole (a lot less than an atomic nucleus in diameter) so it would be a tiny Cthulhu, perhaps a millimetre tall; not all that impressive, I'm afraid.