Question about the big bang.

[Brattus]

Hi!
I am not very well educated. So please go easy on me.
I have a question about the big bang that created the universe.
Could the big bang have occurred in a vastly larger universe?
In other words, could our big bang be a very small bang inside a vastly larger universe?
If a child is lighting a firecracker and the firecracker goes bang then to the child the bang is very cool but very quick. The child then moves rather quickly to the next firecracker.
However if a conscious being was created within the chaos generated by the firecracker bang would that being then perceive the firecracker bang as infinity?
I'm not suggesting we are created in a firecracker, I'm only using that as an example.
I do not know. That's why I'm asking.

 

[Broes]

Hi Brattus,

I am no expert but have read my fair share about it. I hope I can be of some 'assistance'.

"Could the big bang have occurred in a vastly larger universe?"

It seems you assume there already was a universe before the bigbang.

Current belief is that 'before' or at the time of the bigbang our current perceptions on space and time fall apart, there was no universe present.

When you would get close to what we believe to be a black hole, our laws of physics break down. Space and time no longer hold any meaning.
If there would indeed have been a big bang (which seems to be our best assumption at the moment) then our known universe would have started out with singularity (a point in space with no size) with vastly more mass and energy then we can ever see or imagine. Since our normal laws of physics can no longer be applied here, we can also not speak of a 'before' big bang or smaller/larger big bangs.

Also "A vastly larger universe" seems to be a misunderstanding.

The universe as we can see it has no boundry. This can mean several things... either the universe has no boundry (an infinite universe) or the boundry is so far away that we are unable to perceive it (a finite universe).

If the universe is infinite, then you can not have a 'vastly larger' universe. There is no bigger then infinite.

We might hypothyse all we want about what caused the big bang or what was 'before' the big bang but I think we will never know for sure. It kinda all is moot if we have no longer any laws of physics to hold on too, to describe swhat we understand.

I have heard tons of possible scenario's ranging from higher dimensional membrems colliding to an ever recurring cycle of big bang->big crunch->big bang-> etc but it will always be making assumptions, some maybe more plausible then others... Nobody on our little rock we call earth will ever know for sure.

Bruce Jongejans

 

[to.by]

The universe as we can see it has no boundry. This can mean several things... either the universe has no boundry (an infinite universe) or the boundry is so far away that we are unable to perceive it (a finite universe).

No boundary does not necessarily mean infinite. In two dimensions the surface of a sphere has noe boundary, but nevertheless it is finite. Of course you need a third dimension to visualise it. According to GR the space/time continuum is not flat and there is a possibility of it bending back on itself. I seem to remember that Einstein once said that the universe is finite but unbounded.

 

[andyandy]

It seems you assume there already was a universe before the bigbang.

Current belief is that 'before' or at the time of the bigbang our current perceptions on space and time fall apart, there was no universe present.

An interesting idea here is one which challenges our notion of "universe" - ie that of chaotic inflation, in such a scenario, random quantum fluctuations create inflating bubble "universes" - which at the moment of inception lose their causal connection to the area of space in which they're formed - in this case there's no beginning of time, no absolute Big Bang, there just is and always has been and always will be an infinite number of inflating bubbles and post inflationary regions. In such a scenario, one could speak of a time before our own inflationary period (the Big Bang) in which the universe as we curently regard it was part of what is now a causally disjoint meta-universe.....

An article on Parallel Universes - by Tegmark....a really interesting read

 

[Broes]

No boundary does not necessarily mean infinite. In two dimensions the surface of a sphere has noe boundary, but nevertheless it is finite. Of course you need a third dimension to visualise it. According to GR the space/time continuum is not flat and there is a possibility of it bending back on itself. I seem to remember that Einstein once said that the universe is finite but unbounded.

Like I said, "..that we are unable to perceive it"

Another finite model would be an imaginary bubble universe that would expand with the speed of light. This way we would never be able to see the boundaries. This way, the universe would be finite but with unreachable boundaries... till you find a way to travel faster then light...

Bruce

 

[Dancing David]

Hello,
Not an uniformed question at all.

The answer to the question is definite but the meaning is ambiguos.

We don't know.


Due to the current theries of space time it is not possible for us to see outside the universe, know what is outside the universe. that extends back in time and through the future as well. So yes we could be a little universe inside a big universe.

But we can never know.

The real ambiguity comes in when we try to decide what it means to have a universe inside another universe.

And yes you can have an infinity that contains another infinity, a typical example is rational numbers, they are infinite in the size of the set. However they are a subset of the irrational numbers that are also infinite.

 

[Jarom]

And yes you can have an infinity that contains another infinity, a typical example is rational numbers, they are infinite in the size of the set. However they are a subset of the irrational numbers that are also infinite.

I'm sure you meant "subset of the real numbers that are also infinite. Just wanted to avoid any confusion for others reading this thread.

 

[Invidious]

Since blackholes were mentioned, I'd like to add a question about those. If blackholes suck in all this matter and energy and then compress it, what does it all become? I mean, if you take all the elements on the periodic table and squish them into their component parts (or tinier?) what is the resulting element soup called? Or is that not what happens?

Also, to try and tie this back to the OP, is there conjecture that this element soup has some similarity to the singularity speculated at Big Bang?

 

[RecoveringYuppy]

I mean, if you take all the elements on the periodic table and squish them into their component parts (or tinier?) what is the resulting element soup called?

It's no longer an element soup.
It's called a black hole and it appears to be a fundamental particle though some debate remains about whether it's a particle that can decay or not.

 

[rockoon]

There is no rule that black holes must "squish" things.

A black hole the size of the visible universe would be far less dense than water. The mass can easily avoid collapsing into a singularity in such a case, even though none of the mass can escape the mutual gravitation.

That is why there is a distinction between black holes and singularities, and why the search for the Omega constant was such a hot thing before 'dark energy' was detected.

 

[Invidious]

There is no rule that black holes must "squish" things.

A black hole the size of the visible universe would be far less dense than water. The mass can easily avoid collapsing into a singularity in such a case, even though none of the mass can escape the mutual gravitation.

That is why there is a distinction between black holes and singularities, and why the search for the Omega constant was such a hot thing before 'dark energy' was detected.

Okay, I'm halfway through the wikipedia article on this, and (recognizing that w'pedia isn't a great primary source) it seems to indicate that most or all black holes have accretion disks, if not outright spaghettification. From what the article says, it seems as though the forces at work in accretion disks would be enough to strip anything entering them into their component parts, never mind the black hole itself.

Also, thus far it hasn't mentioned the idea that the black hole itself is considered a particle, and also also says that all black holes have a singularity inside. Is this article out of date? (Don't worry about spoiling the end, I'm a ridiculously slow reader and I know the butler did it anyway)

And, so I don't feel so bad about this derail, here's an OP oriented question again: According to one of the relativity threads, space is entirely defined by the amount of time it takes to cross it. If this is the case, and singularities are considered to just be wicked* dense, did time travel faster after the singularity burped or whatever and its mass started to shoot out?

*like, wicked evil dense, not like light the wicked end of that holy candle

 

[blutoski]

Hi!
I am not very well educated. So please go easy on me.
I have a question about the big bang that created the universe.
Could the big bang have occurred in a vastly larger universe?
In other words, could our big bang be a very small bang inside a vastly larger universe?
If a child is lighting a firecracker and the firecracker goes bang then to the child the bang is very cool but very quick. The child then moves rather quickly to the next firecracker.
However if a conscious being was created within the chaos generated by the firecracker bang would that being then perceive the firecracker bang as infinity?
I'm not suggesting we are created in a firecracker, I'm only using that as an example.
I do not know. That's why I'm asking.

This is actually a good question, but the answer is "nobody knows."

The model is called 'multiverse'. Another interesting aspect of this model is that there's no reason to expect other big bang events to produce universes with identical properties. They may have a higher value for the gravitational constant, for example. They may not be able to form stars or planets.

There are related questions that are interesting, too. For example, since the universe is not only expanding, but acceleratingly so, there will come a time when we can't see objects that are very far away because they will be infinitely redshifted. Question: what if there are already objects out there that are travelling so fast they have redshifted to invisibility?

Realistically, we can't know about these other structures or big bang events, pretty much by definition. This makes discussion about them discussion of a 'model' rather than a 'theory'. More philosophy than astronomy.

 

[Invidious]

There are related questions that are interesting, too. For example, since the universe is not only expanding, but acceleratingly so, there will come a time when we can't see objects that are very far away because they will be infinitely redshifted. Question: what if there are already objects out there that are travelling so fast they have redshifted to invisibility?

Could there be objects that are travelling really fast so have redshifted towards invisibility but are travelling fast towards us and are blueshifted, so appear to be just travelling a normal speed?

 

[rockoon]

Okay, I'm halfway through the wikipedia article on this, and (recognizing that w'pedia isn't a great primary source) it seems to indicate that most or all black holes have accretion disks, if not outright spaghettification. From what the article says, it seems as though the forces at work in accretion disks would be enough to strip anything entering them into their component parts, never mind the black hole itself.

This assume that particles must enter through the event horizon of a small black hole. What about the original particles whos collective density became great enough to form an event horizon? Note that collapsing stars is only one way to form a black hole.

A black hole can form around you without you ever knowing that it happened given large enough numbers.

As I pointed out, the density of a black hole the size of the observable universe is much less than that of water. Infact, it is interrestingly near the actual observed density of the universe. (dramatic pause)

This is why there was a big push to find Omega: Will the universe expand forever, or must it eventualy collapse on itself?

You might want to read this:

http://www.mathpages.com/home/kmath339.htm

Also, thus far it hasn't mentioned the idea that the black hole itself is considered a particle, and also also says that all black holes have a singularity inside. Is this article out of date? (Don't worry about spoiling the end, I'm a ridiculously slow reader and I know the butler did it anyway)

This is an external description of a black hole, not an internal one.

Also, anything that tells you that a black hole must have a singularity is lying to you. Clearly an instant after a collapsing star is on its way to forming a singularity, a singularity does not exist yet an event horizon has been formed.

Infinite curvature AT the event horizon does not mean infinite curvature INSIDE the event horizon. That is to say, the curvature created by the mass is related to where that mass is and what shape it has taken. The curvature created by the mass of a dyson sphere (for instance) is equivilent to a single massive particle when taking measurements outside of it. Inside however, a dyson spheres mass does not create any curvature at all.

 

[rockoon]

Could there be objects that are travelling really fast so have redshifted towards invisibility but are travelling fast towards us and are blueshifted, so appear to be just travelling a normal speed?

It is only redshifted when moving AWAY, so no.

 

[RecoveringYuppy]

Question: what if there are already objects out there that are travelling so fast they have redshifted to invisibility?

There are reasons to think that is the case. One is that inflationary theories of the big bang hold that early stages of the big bang created the universe with regions already over our horizon. Another is that the expansion appears to be accelarating so we'd expect that objects are constantly disappearing over the horizon.

 

[Invidious]

It is only redshifted when moving AWAY, so no.

Thanks! Sorry for the dumb question; for some reason I had thought acceleration could cause a red or blue shift irrespective of direction. So much for gleaning physics through reading a forum. I might actually have to read a book (dammit).

 

[rockoon]

Another is that the expansion appears to be accelarating so we'd expect that objects are constantly disappearing over the horizon.

This doesnt sound right.

Our observation horizon is expanding at C and nothing should be able to overtake that, regardless of its acceleration.

 

[RecoveringYuppy]

Not the objects accelaration, the accelaration of the expansion of space.

 

[strathmeyer]

RecoveringYuppy, things aren't moving away from us and "disappearing over the horizon". The expansion of the universe is caused by more space forming between objects, like two dots on an inflated balloon moving apart. Does this make sense?