Cymek said:
The central idea is that the visible, three-dimensional universe is restricted to a brane inside a higher-dimensional space, called the “bulk” (also known as “hyperspace”). If the additional dimensions are compact, then the observed universe contains the extra dimension, and then no reference to the bulk is appropriate. In the bulk model, at least some of the extra dimensions are extensive (possibly infinite), and other branes may be moving through this bulk. Interactions with the bulk, and possibly with other branes, can influence our brane and thus introduce effects not seen in more standard cosmological models.
Some versions of brane cosmology, based on the large extra dimension idea, can explain the weakness of gravity relative to the other fundamental forces of nature, thus solving the hierarchy problem. In the brane picture, the electromagnetic, weak and strong nuclear force are localized on the brane, but gravity has no such constraint and propagates on the full spacetime, called bulk. Much of the gravitational attractive power “leaks” into the bulk.
Could black holes lead and/or leak into the bulk mentioned in brane cosmology ?
Several ideas here. The first paragraph is a bit difficult to sort out, so I’ll skip it.
> Some versions of brane cosmology, based on the large extra dimension idea, can explain the weakness of gravity relative to the other fundamental forces of nature, thus solving the hierarchy problem. Much of the gravitational attractive power “leaks” into the bulk.
You don’t need large extra dimension(s) to explain the weakness of gravity. If all extra dimensions are compact then that works just as well.
What large extra dimensions do is reduce the minimum energy needed to produce a black hole, and at the same time increase the size of the smallest black holes. That’s why the LHC was looking for black holes. Not because they were expected, but because not finding them would help to rule out the “large extra dimensions” idea.
> Could black holes lead and/or leak into the bulk mentioned in brane cosmology ?
Leak into, definitely.
Lead to … I hadn’t thought about that. That’s not such a trivial question to answer.
Even though an electron is “point like” it is still way too big, physically, to fit into a small black hole.
As a black hole becomes bigger, it becomes more and more confined to conventional 3-D space because it simply becomes bigger than the extra curled-up dimensions.
