infinite universe


by Supaiku
Tags: infinite, universe
shifty88
shifty88 is offline
#73
Nov8-11, 10:14 AM
P: 53
Would it be to much of a stretch to say that it would be impossible to ever determine the size and shape of our universe because we are naturally a part of the universe with a limited view.

If somehow we could detach ourselves from the universe (i.e an aerial view of the landscape reveals much more than being on the ground) then we would be able to determine the dimensions of the universe. Whilst we observe it as a whole
phinds
phinds is online now
#74
Nov8-11, 10:48 AM
PF Gold
phinds's Avatar
P: 5,691
Quote Quote by shifty88 View Post
If somehow we could detach ourselves from the universe (i.e an aerial view of the landscape reveals much more than being on the ground) then we would be able to determine the dimensions of the universe. Whilst we observe it as a whole
There IS no "outside" from which we can get such a vantage point, so your question is pretty much equivalent to asking if pigs had wings, could they fly?
Cosmo Novice
Cosmo Novice is offline
#75
Nov8-11, 10:56 AM
P: 366
Quote Quote by shifty88 View Post
Would it be to much of a stretch to say that it would be impossible to ever determine the size and shape of our universe because we are naturally a part of the universe with a limited view.

If somehow we could detach ourselves from the universe (i.e an aerial view of the landscape reveals much more than being on the ground) then we would be able to determine the dimensions of the universe. Whilst we observe it as a whole
What phinds says is correct. If the Universe had an "outside" then it would not be the Universe. The Universe can be defined as: "the totality of everything that exists" therefore if something exists, by definition it is part of the Universe.

For their to be an "outside" would also require a "center" and an "edge" which would invalidate the cosmological principle of isotropy.

We can, however, measure curvature from within the metric to determine if space is euclidean or not - unfornutaley the degree of error is rather small and it is entirely possible that out little patch of the Universe we can see (The Observable Universe) is too small a piece of the whole (Whether finite or not) to determine curvature with any acceptable margin of error.

Global curvature is the key to the "shape" of the Universe in my opinion.

Hope this helps.

Cosmo
shifty88
shifty88 is offline
#76
Nov8-11, 11:17 AM
P: 53
Quote Quote by phinds View Post
There IS no "outside" from which we can get such a vantage point.
Obviously. Therefore we can never know for sure what shape or size the universe it.
We can only use our best educated guess from what observations we can make.
Chronos
Chronos is offline
#77
Nov8-11, 06:01 PM
Sci Advisor
PF Gold
Chronos's Avatar
P: 9,182
The observable universe is obviously finite, so it can expand to its heart's content without offending our logical sensibilities. It is also very close to being dead flat - according to WMAP and supernova studies. This suggests the universe is much larger than the part observationally accessible to us. In is, however, possible the universe could be both flat and finite.
PatrickPowers
PatrickPowers is offline
#78
Nov8-11, 11:38 PM
P: 259
Quote Quote by shifty88 View Post
Would it be to much of a stretch to say that it would be impossible to ever determine the size and shape of our universe because we are naturally a part of the universe with a limited view.

If somehow we could detach ourselves from the universe (i.e an aerial view of the landscape reveals much more than being on the ground) then we would be able to determine the dimensions of the universe. Whilst we observe it as a whole
To me it seems impossible for a finite being to observe an infinity.

It would be possible though to deduce an infinity, by showing that a contradiction occurs if the infinity is not there.

Detaching ourselves from the Universe is by definition impossible. But it could be that our current conception of the Universe is wrongly limited, and there is another view within our Universe that would look at our current conception from outside. Indeed the geometry of spacetime is hyperbolic, and a hyperbolic geometry is one way to fit an infinity inside of a finite space. If there are more than four physical dimensions in our Universe it is possible that there is a perspective in which 4D spacetime is a bounded subset within some other space.
PatrickPowers
PatrickPowers is offline
#79
Nov8-11, 11:40 PM
P: 259
Quote Quote by Chronos View Post
The observable universe is obviously finite, so it can expand to its heart's content without offending our logical sensibilities. It is also very close to being dead flat - according to WMAP and supernova studies. This suggests the universe is much larger than the part observationally accessible to us. In is, however, possible the universe could be both flat and finite.

What do you mean? Spatially infinite but inhomogeneous with a finite amount of matter? That could be.
Chronos
Chronos is offline
#80
Nov9-11, 04:47 AM
Sci Advisor
PF Gold
Chronos's Avatar
P: 9,182
There are at least four possible topologies that are flat, finite and obey the cosmological principal.
vanvlizr
vanvlizr is offline
#81
Nov10-11, 08:46 AM
P: 16
The universe is finite but like explain earlier with an ant on a beach ball to the eye it would seem infinite because the only dimensions we can see is the ones we are in. If you were born and lived on an island all your life you might think that the island is all there is. So if you cannot see an edge to the universe it doesnt make it infinite. To be able to prove non mathematically that our universe is finite we would have to go beyond our own universe but since we cannot detect past the 4th dimension we are stuck.
phinds
phinds is online now
#82
Nov10-11, 09:02 AM
PF Gold
phinds's Avatar
P: 5,691
Quote Quote by vanvlizr View Post
The universe is finite
This is pure speculation on your part and should be stated as an unsupportable opinion, not a fact.
vanvlizr
vanvlizr is offline
#83
Nov10-11, 09:30 AM
P: 16
that is my unsupportable postion atleast with current technology, but it is a fathamable and possible theory. as of now there is no way to be sure, everything about this topic is speculation.
Radrook
Radrook is offline
#84
Nov16-11, 07:29 PM
P: 334
Quote Quote by phinds View Post
This sounds like philosophical nonsense run amuck, and should be posted in the philosophy section, not here where we base our statements on evidence.

Can you specify exactly what is so nonsensical about what he just said.
Radrook
Radrook is offline
#85
Nov16-11, 07:35 PM
P: 334
Quote Quote by phinds View Post
This is pure speculation on your part and should be stated as an unsupportable opinion, not a fact.

The question is why state opinion as if it were fact in the first place. If indeed the universe is finite then it is bounded. Which brings up the question as to what is outside those boundaries. If indeed there is nothing outside, then that answer itself becomes nonsensical because it is self contradictory. In short, it is identical to the "Who created God" paradox of infinite regression. The only way around it is to negate the existence of dimensionality and to declare its perception as a sensory illusion.
phinds
phinds is online now
#86
Nov16-11, 07:58 PM
PF Gold
phinds's Avatar
P: 5,691
Quote Quote by Radrook View Post
Can you specify exactly what is so nonsensical about what he just said.
Uh ... did you READ the post that was in response to???
genius01
genius01 is offline
#87
Jan6-12, 02:12 PM
P: 4
Its hard to actually understand how exactly did they measure the size of the universe? I am also quite concerned with the fact that there could still be an outer void of nothingness located somewhere out of the universe. What if dimensions aren't tightly packed like said in string theory

1: is a straight line that has 2 directions of spatial freedom and is infinte (is also infinitely thin)
2: is a combination of two 1 dimensional lines and has 4 directions of spatial freedom it is also infinitely thin (because it has no depth)
3:It is an increase in spatial freedom in which is depth is the increase (since it has depth then we would now assume it is not infinetly thin
4: Now there is the temporary dimension which is used for measurement of physical change and then there is the spatial dimension which is a tesseract.
now it may seem pointless to have told you this but its confusing how we would consider dimensions tightly compressed. So why does string theory assume its tightly compressed as moving forwards in dimensional states increases physical state ?
ccarey221
ccarey221 is offline
#88
Nov15-12, 08:46 PM
P: 1
The outside of the universe is literally nothing. We observe the end of the universe, though it is not the true end of the universe because the time-space continuum doesn't allow us to view the true edge. The universe is forever expanding and new galaxies far away have been created, possibly billions of years ago, but because of the distance, the light reflecting off of those galaxies may not have reached us yet, allowing us not to view them, or if the light has recently reached us, we would view it as a new galaxy, though it was truly just too far to allow the reflected light to reach us. It is only logical that the universe is constantly expanding because the entropy within the universe is forever increasing. There is a good point made in this article http://www.allaboutscience.org/theory-of-relativity.htm
Only if we could go the speed of light could we determine the current dimensions of the universe


Register to reply

Related Discussions
The Universe - infinite or not ? Cosmology 139
the infinite universe Cosmology 2
Infinite-infinite universe explains all General Discussion 42
Does an infinite universe effect an infinite outlook? General Astronomy 11