The discussion centers around the question of why the early universe did not collapse into a black hole despite being extremely dense and small, particularly during the period of inflation. Participants explore concepts related to cosmology, gravitational forces, and the nature of the big bang.
Participants express a variety of views on the reasons behind the early universe's expansion and the absence of black hole formation, indicating that multiple competing perspectives remain. There is no clear consensus on the mechanisms at play or the nature of the initial conditions.
Some claims rely on specific definitions and assumptions about gravitational forces and cosmological models, which may not be universally accepted or understood among participants.
I'm missing some points in here; there was space in singularity, wasn't it? Quoting SciAm June 2008, page 53, "at the time of inflation, our observable universe was less than a centimeter across." That's space, no?
Yes, that's the size of the observable universe -- the patch of spacetime within which all events are causally related. However, the actual universe is a patchwork of these causal regions. The big bang was not a localized event -- it happened everywhere at once. Keep in mind, that the big bang model does not address the initial singularity -- it is believed that the singularity is signalling a breakdown of the mathematical theory at this time, rather than representing something physical. So the big bang is the cosmological model that describes how the early universe expanded from a hot, dense phase into a cooler, less dense phase. This expansion, by all accounts, has been uniform and isotropic because the energy density is uniform and isotropic. An energy density of this form does not give rise to a gravitational field, and therefore does not yield black hole solutions.shazdeh said:
Indeed, but I think it's important not to put too much focus on the amount of energy, or the rapidity of the expansion, or the strength of gravity. It's really a matter of symmetry -- a uniform spacetime of critical density will expand (or contract) -- it will not form a black hole.Naty1 said:
There will always be more mass "below" you than "above" you as fall towards the center of the earth. As Naty1 says, only at the very center will the net gravitational force be zero.shazdeh said:
If the hole is completely straight through the Earth, inertia would tend to carry a body on past the center where the gravitational force is zero.and into an oscillation mode through the center. But the rotation of the Earth would keep the body scraping the side of the hole which would eventually bring the remains to rest at the bottom.bapowell said:
CBLeffert said:
derek101 said: