4 ms·
That would add a directionality component as some objects closer to said black hole would accelerate faster. A more plausible but unprovable option is that we
by marcyb5st 5y ago
That would add a directionality component as some objects closer to said black hole would accelerate faster.
A more plausible but unprovable option is that we are close to the center of a big void (the density of the matter in our neighborhood is much lower than outside the observable universe). So the higher mass concentration attracts objects in our neighborhood giving the impression of an accelerating expansion.
The problem with this theory are that we would have to be almost at the center of this bubble of almost nothing (so the notion that earth is not in a special position is lost) and that if spacetime is not expanding we cannot explain why very distant galaxies recede from us faster than light. FTL travel though spacetime should be impossible but spacetime expanding faster than light is.
- gizmo686 5y agoIf we are within the event horizon, then the direction towards the center of the black hole is not a spatial direction, but a temporal one. The cental singularity is in the future. As it turns out, the temporal direction is the only direction of spacetime which is not symetric. Objects in the future are accelerating faster, which is presisly the prediction you made.
- AnimalMuppet 5y agoIf I understand correctly, if you add up the mass in the universe, the Schwarzchild radius of that mass is 13 billion light years, which is a really interesting number. If we were inside a universe-sized black hole, would we be able to tell? Can we experimentally distinguish a black hole universe from a not-black-hole universe?
- marcyb5st 5y agoGood point! However, inside an event horizon we should have a preferred direction in which all the light cones that can catch up to us actually catch up to us (if Penrose diagrams hold true within an event horizon). That would mean that looking in that direction the universe would appear brighter and given how smooth is the CMB that doesn't seem to happen. It could still work if we assume that when this black hole was created either everything or nothing was causally connected to us. Fascinating point!