Is our universe inside a blackhole?

[Haktarfone]

Let's start off with what we know about black holes; It is formed through a colossal explosion of a star. So, I want you and your silly little friends that work in the Physics department to think about this deliberately: The Big Bang tells you that the universe was formed through a explosion that laid out the stuff that make you, me and also your monitor screen.

So, is it possible that we are a product of an explosion of a giant star (that turned into a black hole) in some other universe?

 

[Jimmy]

See the following entry in the https://www.physicsforums.com/forumdisplay.php?f=206:

https://www.physicsforums.com/showthread.php?t=506992

 

[phinds]

Let's start off with what we know about black holes; It is formed through a colossal explosion of a star. So, I want you and your silly little friends that work in the Physics department to think about this deliberately: The Big Bang tells you that the universe was formed through a explosion that laid out the stuff that make you, me and also your monitor screen.

So, is it possible that we are a product of an explosion of a giant star (that turned into a black hole) in some other universe?

For this, and many other basic questions, you should get in the habit of doing a forum search. This particular question gets asked/answered at least a couple of time a month.

 

[PeroK]

This particular question gets asked/answered at least a couple of time a month.

But usually without the condescension.

 

[phinds]

But usually without the condescension.

Huh?

 

[Chronos]

New ideas get discussed here when they are published in a peer reviewed paper. Otherwise, it just looks like a personal theory. See forum rules for further details.

 

[vociferous]

Is it possible? Well yes, in science we recognize anything is possible, even if it is extremely unlikely.

There are a number of different multiverse proofs that explain the big bang and some of them involve black holes. I'm not sure any of them would qualify as a fully legitimate scientific theory at this point because they are difficult or impossible to corroborate or disprove.

From the wikipedia article on the subject:

Pathria, R. K. (1972). "The Universe as a Black Hole". Nature 240 (5379): 298–299.

Good, I. J. (July 1972). "Chinese universes". Physics Today 25 (7): 15.

Landsberg, P. T. (1984). "Mass Scales and the Cosmological Coincidences". Annalen der Physik 496 (2): 88–92.

Popławski, N. J. (2010). "Radial motion into an Einstein-Rosen bridge". Physics Letters B 687 (2–3): 110–113. arXiv:0902.1994.

Popławski, N. J. (2010). "Cosmology with torsion: An alternative to cosmic inflation". Physics Letters B 694 (3): 181–185. arXiv:1007.0587

Popławski, N. (2012). "Nonsingular, big-bounce cosmology from spinor-torsion coupling". Physical Review D 85 (10): 107502. arXiv:1111.4595

 

[Drakkith]

But usually without the condescension.

Huh?

The OP's post comes off as a little condescending, whether they intended to be or not.

 

[phinds]

The OP's post comes off as a little condescending, whether they intended to be or not.

Oh, yeah, it did at that. I don't pay much attention to that stuff sometimes but this one was a bit over the top.

 

[Drakkith]

Let's start off with what we know about black holes; It is formed through a colossal explosion of a star.

Actually a black hole is not formed from an explosion, but an implosion. It is possible for a black hole to form without a supernova, and many supernova occur without the formation of a black hole (type 1a supernovas for example).

 

[tadchem]

The "No-Hair" Theorem applies. It is a mathematical statement that demonstrates that a BH can only have a very limited number of properties, and no internal structure of any kind. Basically, a BH is a quantum mechanical object on a cosmic scale, with charge, mass, and angular momentum, but no quadrupole or higher magnetic or electrostatic moments, no shape, no entropy, no other thermodynamic properties.

 

[MattRob]

For this, and many other basic questions, you should get in the habit of doing a forum search. This particular question gets asked/answered at least a couple of time a month.

How often do physicists approach the question and analyze it?

If it gets asked on here a couple of times a month, I get the impression it's something that's been mulled over quite a bit and has had quite a bit of academic material published on it?

It seems like an intriguing question, though. I'm aiming to become a relativist myself, and it looks like the sort of thing I'd love to do original research on.

Heh, I'm not sure whether I'm disheartened by the thought of it being something that a huge number of people have already worked on and thus beat me to any conclusions I can make or any insights I can provide - or if I'm excited at the prospect to be able to build off of their work and go further by standing on their shoulders, so to speak.
Actually, I wasn't planning to hit on the question itself, but reading the links here, I've found a thing I'm curious about...

From here, which was linked from https://www.physicsforums.com/showthread.php?t=506992.

...The short answer is that the Big Bang gets away with it because it is expanding rapidly near the beginning and the rate of expansion is slowing down...

Isn't that only true in the original Big Bang model, though? I thought the core feature of Inflationary Cosmology was that the rate of expansion increases in the first moments, allowing for the universe to come so close to thermal equilibrium to create the mostly thermally homogeneous universe that we observe.
That being said, I'm not too confused, though, thanks to Greg's explanation in addition to that one... It makes sense to me that there'd be a huge difference in-between a region of high density surrounded by flat spacetime, as opposed to an entire universe of extreme density. After all, what region would an event horizon form and enclose, if all of space is homogeneously past critical density?

That being said, if there were some sort of space outside the space of our universe (however that would work; let's call this "outer space"), then I guess our universe would be a black hole there, because the event horizon would enclose the region of space associated with all of our space.

Thought: "all of our space" may be infinite, but finite within "outer space" because of how a dimension of time has swapped roles with a dimension of space upon crossing the event horizon. It's not just the singularity that I find uncannily similar to a black hole and our universe - it's other features, such as this, as well - how the bubble universes of a "Swiss Cheese" inflationary cosmology multiverse, when viewed from outside, have a number of similarities to black holes (can be bigger on the inside, outermost regions correspond to first moments in time, involve extremely dense matter, etc.).

 

[Chronos]

Good luck in proving the existence of an 'outer space' in your version of the BB. I look forward to reading your peer reviewed papers on this topic.

 

[MattRob]

Good luck in proving the existence of an 'outer space' in your version of the BB. I look forward to reading your peer reviewed papers on this topic.

On further thought, Inflationary Cosmology already has an 'outer space', doesn't it? The point where the quantum uncertainty initiates a "big bang" that causes a region of space to expand; the space outside of that expanding region might qualify?

Heh. That's an interesting thing, actually... The region inside a black hole is disconnected from its exterior, isn't it? Nothing, traveling along spacetime, can escape the event horizon, so I wonder if anything outside can ever catch up to anything that's already passed the event horizon? In other words, could an observer inside a black hole ever probe the space outside the black hole? I don't think so. From an outside frame of reference; escaping the event horizon is simply impossible without modifying the black hole's structure. From an inside frame of reference, it would be analogous to going back in time to before the first moments of the big bang, if I understand the time-space swapping roles thing correctly.

Not to say it wouldn't have implications and effects on the universe that could otherwise be used to discover its presence...

Thank you, though it may be awhile since I'm only a lowly undergrad Sophomore that really shouldn't know any of this (I sure do love jumping in over my head!). Doesn't mean I can't bother my professor about things like this, though, heh (But then I'm not attending for the current semester for medical reasons, so it'll even be a few months before I even have an astronomy professor to bother, unfortunately). Or talk about these things on these forums, which seems to be my only option at the moment for a two-way discussion on these sorts of things.

When I look at the kinds of mathematics required for solutions to GR, though, I don't think I can ever forget a line from Kip Thorne's Black Holes and Time Warps: apparently at one point Grossman (I think Marcel Grossman) told Einstein that Differential Geometry is "a terrible mess which physicists should not be involved with." Trying to read about it on Wikipedia, I think I see why he said that. It's both very daunting and exciting.

 

[phinds]

How often do physicists approach the question and analyze it?
...

As far as I'm aware, just about none. Apparently it's pretty immediately apparent to serious cosmologists that it does not describe reality so why would they waste time on it?