[mcswell]

>> The black hole in the parent universe must be much much bigger than >> anything we see in ours

>> Yes and no. You're not thinking about contraction. With relativity >> we can fit a 100ft ladder inside a 10ft barn.

I believe the OP was talking about mass, not linear dimension. (And if he wasn't, I am.) Unless somehow mass inside a black hole is not constant? (ignoring accretion)

[godelski]

Relativity applies to mass too. Accelerate and you become heavier.

Remember, mathematically, a blackhole is mass in an infinitely small point. You are dividing by 0. I don't know the answer, but if someone is saying that from the outside the apparent mass is different than from the inside, that doesn't set off any alarm bells. We literally are talking about Dr Who style "it's bigger on the inside". Even the ladder example should make you think about mass. Without relativistic effects the mass inside the barn is only part of the ladder. With relativity, the whole ladder, and thus mass, is inside. So yeah, weird things happen.

[blamestross]

*aparent mass goes up

Things don't get more mass, they just take more energy to accelerate which looks a lot like more mass.

It doesn't imply for example, a high speed mass would cause more gravitational attraction than a slow one.

If that was the case, a black hole would be even worse as it accelerates matter towards itself and it gains "bonus mass"

[kosh2]

Black holes have the same mass and information as the stars that formed them.

Unless the theory also breaks mass and information conservation, the star that gave birth to our black hole must have been as massive as our entire universe.

I doubt we have any theory how a star that size can have formed.

[godelski]

I meant apparent mass. Just dropped the apparent because we're on HN and anyone familiar with relativity is likely going to know what I mean. I mean if actual mass went up we'd be violating conservation of energy. It's all about your frame of reference and you can treat these things as local systems.