Does the UNIVERSE have a boundary or OUTER LIMIT?

A boundary is an illusion.
If time had a beginning, then time was created, at which point creation would require time itself. See the paradox here? Even for existence to sponateously assemble from nothing, it would need time to do so. It has changed states, and therefore time. Even "vibrations" (string theory)require time to "vibrate". Time is infinite.

Can time have an end?... well... does infinity have an end? Not likely hence "infinity".

Can "space" have a boundary?

The universe has infinite spatial volume even if there was a "big bang". Energy needs space and time to expand. What could the universe be expanding into? The only boundary to space is one where time is not present. In which case existence becomes stagnant, motionless. But time is infinite, so space must be also, they co-exist. We percieve vacuous space in the absence of light and that's where dark matter comes in. We cannot see it, but it's there.

Could time-space (the universe) expand into nothing? Could existence expand into non-existence, or vice versa?

For time-space to have a boundary, it must be surrounded by non-existence, no space-time, essentially nothing, in which case there isn't a boundary, only a percieved boundary.

I would say that the universe (existence) has no boundaries, but we humans always search for beginnings and ends, and this is where logic breaks down. Giving a beginning and an end to infinity is impossible.

Infinite expansion is the same as infinite contraction.

People have this funny idea that space will 'stop' expanding, and then begin to contract...haha...

It's happening at the same time (and I am loathe to use the word time).


Did I mention that the English language has not a future tense?

~Wen typed:~ Infinite expansion is the same as infinite contraction. ~regarding the total volume perhaps, but the average spacing between galaxies 8 billion light years apart is definitely affected.
Personally I hope we will go with a finite volume, boundaries and a center as in usual human visualization, but I suppose the Universe is little interested in my hopes.
I picture a double boundary; perhaps 30 light years from the center marked by the farthest reaching sub atomic particle; and a boundary about 30.01 billion light years marked by the farthest reaching photon or neutrino. Both boundaries are moving outward at nearly light speed as a photon becomes matter occasionally, and a particle emits a photon occasionally. The most distant planet size body may be only 20 billion light years from the center. Not much of interest would be happening in that outer ten billion light years. That means we could be up to 8 billion light years from the center if the farthest we can see is 12 billion light years.
There may be nothing interesting happening at the center, or new matter may come into existence more often there than elsewhere, but that also seems counter intuitive. Neil~

Yes I know, old topic, but about this Big Bang theory like stated, if it was started as a pinprick and then expanded in all directions, what was there FIRST to hold this material and how big is it!? Ever think about that?

Cosmological guesswork. That's all that these topics can ever be!

Consider that "Knowledge", direct, substantiated, experiential reference of observed phenomona, depends first and foremost on observation. Only that which can be substantiably observed, or be in academically valid manner deduced through correllation of substantiable observations, may be "Known".

That which is beyond current observational capability by definition cannot be known. In regard to the universe in which we find ourselves, all that may be said with any confidence or precision is that the universe in which we find ourselves has observable limits.

To be considered as well is the fact that as mankind's grasp of technology has increased, so too have increased the boundaries of that which is observable. Whatever there may be to know, there is much we have yet to know, and much we will come to know.

I know! :wink:

I have a theory which I would not be able to back up due to the ignorance on the topic but here we go...

I think that black holes suck in space matter and in order for the universe to not be completely sucked up they replace the matter back into the universe...or something like that...comment all those who know to tell me how it is...

So is the Black Hole the boundary then?

maybe...I don't know...thats what I thought could be...mayby it sucks in and places at the beginning the same matter...a continuem...

As one A2K member said on another thread..."Our Universe sucks!"

Looks like you may be onto something. :wink:

Thats why I posted it, I would like to see what people believe on this theory...I am no expert, so experts go ahead....

Why don't you invite Rosborne979 over...he's knowledgeable on this subject?

I'll give him a buzz.

furiousflee, see Ted Bunn's Black Hole FAQ

You might also wanna learn a little about Hawking Radiation

I will check it out some other time....don't have alot of time....but hey...what do you think about the theory?

re the theory, I'm no expert, but I'd say its got some holes in it :wink:

Hi Furiousflee,

Bib asked me to comment on your theory...



I don't know of any universal requirement for a balance between what goes into a black hole and what has to come back out of it.

Also, if a black hole were required to "replace" all that is absorbed, then they probably wouldn't form in the first place because it's the accumulation of mass itself which is the black hole.

As an aside to the general idea of "balance", Hawking proposed "evaporation" of black holes due to an imbalance of virtual particles which are captured by the event horizon. And recently Hawking announced that black holes do indeed disgorge information at some point in their lives/deaths, but that the information is in "raw" (torn apart) form. I'm not quite sure I understand what Hawking was talking about with that latest announcement, but the virtual particle thing makes sense.

Hope that helps

Ros: my understanding of Hawking's latest thoughts on Black Hole Cosmology, with respect to raw data being disgorged, is the massive gravitational forces which are resultant from the build up of ever-increasing matter accumulation, are so destructive during the exhaust phase, that what is ejected is literally raw material.

Yeh, but what I don't understand is the concept of an "exhaust" phase itself. As far as I know, there is no way for "anything" to escape a black hole, and the hole doesn't require any additional input to perpetuate itself.

I understand the part about imbalanced virtual particles escaping, but that's because one of the two particles is postulated to come in to existance "outside" the event horizon, which would allow its escape.

Other than that, I don't know how Hawking proposes anything escaping the hole, but he seems to be saying there is a way. I'll figure it out eventually (I hope)

Best Regards,

From what I gather, he's saying it will happen after enough mass is lost by the BH for the singularity to break up. At that point the material sucked in during the life of the BH would be expelled in a raw form. By raw I think he means like subatomic raw. It would take a very long time for it to happen, it's doubtful the universe is even old enough for it to have happened at all yet. Still, sounds like a better idea than "mini universes" to me.