<p>Taking into consideration the big bang theory and the followed expansion of our Universe, was there a time when density of the Universe created an event horizon?
If so, then for how long and how is it that it kept expanding despite such an enormous density and space-time deformation?</p>
<p>I did a very brief estimation for only barionic and dark matter taking into account that there are about 1e11 estimated galaxies in observable Universe and there are about 1e11 stars per galaxy (red dwarfs are most common, but I used the Sun's mass) and that the dark matter equals about 4 time barionic matter - the online calculator showed an event horizon as ~1e11 ly.</p>
<p>Was this result in the right ballpark and what does it imply if so?</p>
<p>PS. I've seen similar questions here, so pointing to some articles will be fine, explaining consequences will be even better</p>
<p>PS. My question does not seem to be answered by the one mentioned in the closing comment, as suggested to me I edit to reopen it.</p>
<p>Edit (3/25)
As far as I understood the &quot;duplicate&quot; question is about potential event horizon if the Universe's density was at a point, i.e. if the Universe was a black hole, which it obviously is not (as I read somewhere), my question was that some time in the past the Universe had to be dense enough to be one, if not why not, if yes, why it kept expanding and what happened to the event horizon.</p>
<p>I see it as either eternal inflation is the case and there has never been a singularity or the early Universe had something black holes do not, which made it to keep expanding, or simply just the fact that space-time arose from the singularity it has never been a black hole.</p>
<p>Just wanted to ask what the current theories (especially GR) can say about it.</p>
<p>thanks</p>

CC BY-SA 4.0
2021-03-01T02:08:28.617Z
I don't think the question is closed correctly. This question looks to be asking whether the density of the early universe formed a black hole event horizon, while the linked duplicate question is asking about a mostly unrelated coincidence.
BMF
CC BY-SA 4.0
2021-03-24T16:59:53.183Z
Yes, thank you. I am asking about the event horizon of the early universe, which had to be dense enough at some point (was it? did it disappear? if not - why?). An eternal inflation would've possibly solved it, but I would welcome some comments on this.
Radoslaw Garbacz
CC BY-SA 4.0
2021-03-24T17:14:37.407Z
I think you should make an edit to the question to bring it back onto the site's activity feed. That way it might be reopened (or perhaps closed correctly if there is a duplicate on this site--though I can't find one).
BMF
CC BY-SA 4.0
2021-03-25T02:25:32.263Z
Radoslaw, I don't understand why the accepted answer to the duplicate question doesn't provide what you need. It estimates the Schwarzschild radius (i.e. the event horizon) of the observable universe at 475 Gly – about 4x the estimate you give. This should imply that the observable universe is *already* inside a black hole (i.e. there's no need to look back to the early universe for the necessary density), but the answer explains why this isn't so. I don't think your current edit is sufficient to warrant reopening your question.
Chappo Hasn't Forgotten
CC BY-SA 4.0
2021-03-25T02:31:26.083Z
If the duplicate's answer doesn't provide the explanation you're looking for, then I recommend you *substantially* edit your own question. Add a link to the duplicate, and *explain in some detail what you're looking for* that the duplicate's accepted answer doesn't address.
Chappo Hasn't Forgotten
CC BY-SA 4.0
2021-03-25T02:39:19.357Z
Yes, as the previous comment suggest, please help by adding to the edit explaining what it is that still needs to be addressed. *Thanks!*
uhoh
CC BY-SA 4.0
2021-03-25T02:39:41.277Z
See also the [linked Physics.SE question in a comment on the duplicate](https://physics.stackexchange.com/questions/174665/how-can-the-schwarzschild-radius-of-the-universe-be-13-7-billion-light-years), the answer to which makes it clear that it's meaningless to apply the Schwarzschild metric to the universe as a whole. [It also gives an estimate of the radius of the event horizon for a mass equivalent to that of the observable universe and comes up with ~500 Gly, which is very close to the estimate in the duplicate question.] :-)
Chappo Hasn't Forgotten
CC BY-SA 4.0
2021-03-25T17:35:37.107Z
Thank you for the comments, as far as I understood the "duplicate" question is about potential event horizon if the Universe's density was at a point, i.e. if the Universe was a black hole, which it obviously is not, my question was that some time in the past the Universe had to be dense enough to be one, if not why not, if yes, why it kept expanding and what happened to the event horizon. However I will review the referred question/answer more detail, in case I misunderstood (I am not an astrophysicist).
Radoslaw Garbacz
<big-bang-theory><event-horizon>
Early (high density) Universe's event horizon
Radoslaw Garbacz
# Early (high density) Universe's event horizon

(Asked by: username_0 on 2021-02-25)

Taking into consideration the big bang theory and the followed expansion of our Universe, was there a time when density of the Universe created an event horizon?
If so, then for how long and how is it that it kept expanding despite such an enormous density and space-time deformation?

I did a very brief estimation for only barionic and dark matter taking into account that there are about 1e11 estimated galaxies in observable Universe and there are about 1e11 stars per galaxy (red dwarfs are most common, but I used the Sun's mass) and that the dark matter equals about 4 time barionic matter - the online calculator showed an event horizon as ~1e11 ly.

Was this result in the right ballpark and what does it imply if so?

PS. I've seen similar questions here, so pointing to some articles will be fine, explaining consequences will be even better

PS. My question does not seem to be answered by the one mentioned in the closing comment, as suggested to me I edit to reopen it.

Edit (3/25)
As far as I understood the "duplicate" question is about potential event horizon if the Universe's density was at a point, i.e. if the Universe was a black hole, which it obviously is not (as I read somewhere), my question was that some time in the past the Universe had to be dense enough to be one, if not why not, if yes, why it kept expanding and what happened to the event horizon.

I see it as either eternal inflation is the case and there has never been a singularity or the early Universe had something black holes do not, which made it to keep expanding, or simply just the fact that space-time arose from the singularity it has never been a black hole.

Just wanted to ask what the current theories (especially GR) can say about it.

thanks

**Tags:** big-bang-theory, event-horizon
> **Comments:**
> **username_1**: I don't think the question is closed correctly. This question looks to be asking whether the density of the early universe formed a black hole event horizon, while the linked duplicate question is asking about a mostly unrelated coincidence.  
> **username_0**: Yes, thank you. I am asking about the event horizon of the early universe, which had to be dense enough at some point (was it? did it disappear? if not - why?). An eternal inflation would've possibly solved it, but I would welcome some comments on this.  
> **username_1**: I think you should make an edit to the question to bring it back onto the site's activity feed. That way it might be reopened (or perhaps closed correctly if there is a duplicate on this site--though I can't find one).  
> **username_2**: Radoslaw, I don't understand why the accepted answer to the duplicate question doesn't provide what you need. It estimates the Schwarzschild radius (i.e. the event horizon) of the observable universe at 475 Gly – about 4x the estimate you give. This should imply that the observable universe is *already* inside a black hole (i.e. there's no need to look back to the early universe for the necessary density), but the answer explains why this isn't so. I don't think your current edit is sufficient to warrant reopening your question.  
> **username_2**: If the duplicate's answer doesn't provide the explanation you're looking for, then I recommend you *substantially* edit your own question. Add a link to the duplicate, and *explain in some detail what you're looking for* that the duplicate's accepted answer doesn't address.  
> **username_3**: Yes, as the previous comment suggest, please help by adding to the edit explaining what it is that still needs to be addressed. *Thanks!*  
> **username_2**: See also the [linked Physics.SE question in a comment on the duplicate](https://physics.stackexchange.com/questions/174665/how-can-the-schwarzschild-radius-of-the-universe-be-13-7-billion-light-years), the answer to which makes it clear that it's meaningless to apply the Schwarzschild metric to the universe as a whole. [It also gives an estimate of the radius of the event horizon for a mass equivalent to that of the observable universe and comes up with ~500 Gly, which is very close to the estimate in the duplicate question.] :-)  
> **username_0**: Thank you for the comments, as far as I understood the "duplicate" question is about potential event horizon if the Universe's density was at a point, i.e. if the Universe was a black hole, which it obviously is not, my question was that some time in the past the Universe had to be dense enough to be one, if not why not, if yes, why it kept expanding and what happened to the event horizon. However I will review the referred question/answer more detail, in case I misunderstood (I am not an astrophysicist).  

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