-1
$\begingroup$

When our entire section of the universe was in a single hot dark dense state, right before our big bang, what was the escape velocity?

$\endgroup$
10
  • 4
    $\begingroup$ You can’t escape from the universe. The universe doesn’t have an escape velocity, so the question is based on a false premise. $\endgroup$
    – Ghoster
    Commented Mar 20 at 23:52
  • $\begingroup$ I meant our section of the universe, not the universe. $\endgroup$
    – user394592
    Commented Mar 20 at 23:53
  • $\begingroup$ Plus, whether or not you can escape from the universe, can an escape velocity be calculated for a single hot dark dense state consisting of one big bang of mass anyway? $\endgroup$
    – user394592
    Commented Mar 20 at 23:57
  • 2
    $\begingroup$ There is no such thing as “one big bang of mass”. $\endgroup$
    – Ghoster
    Commented Mar 20 at 23:58
  • $\begingroup$ It isn’t clear what you’re talking about. I consider the Big Bang to have been the limit $t\to 0$ or $a\to 0$ in a Friedmann model. Talking about what was before this singularity is meaningless. Are you talking about immediately before inflation? If so, that’s vague because there are lots of inflationary models. $\endgroup$
    – Ghoster
    Commented Mar 21 at 0:01

1 Answer 1

2
$\begingroup$

To answer your question, it is worth noting that “escape velocity” is a term frequently used concerning objects within gravitational fields whereby an object opposes the gravitational pull of another. This point (in the case of the Big Bang singularity) represents the whole universe in an extremely dense form rather than a localized field of gravity consisting of distinct objects. Let us also consider the idea of the entire universe as one massive body (even though this is not wholly accurate) for argument's sake, then calculating its escape speed would be meaningless since there is no external field of gravitational force to escape from. The universe would amount to nothing else besides itself and thus cannot have any other thing against which to measure escape velocity. In the context of Big Bang, however, expansion does not need to achieve escape velocity in the usual sense. Instead, it occurs because space itself undergoes a rapid expansion as described by cosmic inflation theory and later by general relativity's description of accelerated expansion of the universe. Thereby, the existence of this expansion does not necessarily imply that universal magnitude has achieved a certain specific rate relative to some kind of external gravitational field but simply indicates that such motion characterizes its structure as it changes over time for all matter-energy with respect to inertia according to fabric physics nature.

$\endgroup$
6
  • $\begingroup$ Thank you for your answer, but if big bangs are natural and they occur somewhere in the universe then would there be an escape velocity from the single hot dark dense state with a mass of one big bang, and if so, what would that be? $\endgroup$
    – user394592
    Commented Mar 21 at 0:35
  • $\begingroup$ @MarkSwartz that's not how it works, and any velocity would be meaningless. $\endgroup$
    – JEB
    Commented Mar 21 at 0:38
  • $\begingroup$ @MarkSwartz You don't really understand what the Big Bang is. Try this video from Sabine Hossenfelder. $\endgroup$ Commented Mar 21 at 0:50
  • $\begingroup$ Thank you for the video $\endgroup$
    – user394592
    Commented Mar 21 at 1:17
  • $\begingroup$ Advertising thank you for your answer, but if after stellar collapse, the original space remains and only the matter is compressed, doesn't that imply that big bangs go into original space, and only the matter is bulkier? $\endgroup$
    – user394592
    Commented Mar 21 at 14:22