4 ms·
Wait, what? So admitedly, a few (bilion) years back, when the universe had a radius smaller than ~14B ly, it was sufficiently dense to be a black hole? I mean
by xgbi 10y ago
Wait, what?
So admitedly, a few (bilion) years back, when the universe had a radius smaller than ~14B ly, it was sufficiently dense to be a black hole?
I mean, what ? Our universe did not lose mass in between (if we admit that it is a "closed" system), so at some point in the past, it grew out of being a black hole when it expanded above its Schwartzschild radius?
- Retric 10y agoAs long as you have ~uniform density out to the edge of the observable universe you get zero net gravity. Move over 1 light year and that particle also sees ~uniform density out to the edge of it's observable universe and you don't get a vast black hole.
- pdonis 10y ago> a few (bilion) years back, when the universe had a radius smaller than ~14B ly, it was sufficiently dense to be a black hole? > at some point in the past, it grew out of being a black hole when it expanded above its Schwartzschild radius? No and no. The calculations of the "Schwarzschild radius" corresponding to a given mass assume that the mass is static. They do not apply to an expanding universe.