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# If the universe doubled in size, would it actually be any bigger?

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1. But then if spacetime is STRECHED, then the speed of light has also doubled
so we might not notice any extra relativistic effects..

if you do this,

gamma = 1/[1-(V^2/c^2)]
double V because V=x/t and x doubles
double c because light travels twice as fast (remember V only doubles if we STRECH space, if we just add another universe sized chunk onto the side none of this will change)

new gamma = 1/{1-[(2V)^2/(2c)^2]} = 1/[1-(4V^2/4c^2)] = 1/[1-(V^2/c^2)] = old gamma

so no effect (in special relativity)
I THINK!"
2. If EVERYTHING was doubled it wouldt have changed, and it wouldt be diffrent.

Say your house was doubled, if the things inside were not then yes there would be a diffrence.

If your house AND all the things inside your house was doubled, it would not make a diffrence and you would not notice.

or somthing, i duno i just made that up

infinity x infinity = infinity
3. (Original post by BhArJ)
infinity x infinity = infinity
surely...

n x n = ?
4. (Original post by technik)
surely...

n x n = ?
hmmm but infinity is never ending, how can you have somthing which never ends doubeld?
5. (Original post by technik)
surely...

n x n = ?
But that is squaring infinity, surely it would be 2n since it would be n x 2.
6. (Original post by wiwarin_mir)
But that is squaring infinity, surely it would be 2n since it would be n x 2.
n + n = 2n

n * n = n^2
7. what does this have to do with space doubling? it is a finite length across, so why worry.
8. (Original post by BhArJ)
hmmm but infinity is never ending, how can you have somthing which never ends doubeld?
im going to modify your post...see if it makes sense :

"hmmm but infinity is never ending, how can you have somthing which never ends"

pickler
9. (Original post by technik)
im going to modify your post...see if it makes sense :

"hmmm but infinity is never ending, how can you have somthing which never ends"

pickler
lol good point, but what about numbers? you can not have a end number, so its Infinite, isnt it?
10. oh shyte the actual question is about the universe length doubling.
so no, it would be the same! ie as the universe is thought be be expanding, nothing is changing?
11. (Original post by technik)
surely...

n x n = ?
Wasn't the thread about what would happen if the universe was doubled though, in which case it would be simply:

n + n or n x 2, both of which = 2n, not n^2.

Given the fact that what you're trying to do equates to, basically, n+n (ie. infinity plus infinity), it must be impossible*, since you can't add to an infinite series.

(*assuming that the universe is infinite - I don't know about these things, but that seems to be what the clever-sounding physics people are saying!)

ZarathustraX
12. Like I first said it depends if you simply add another univrseon the side, or the current one is streched to double its volume.
13. (Original post by technik)
"hmmm but infinity is never ending, how can you have somthing which never ends"

pickler
Do you mean in the temporal or spatial sense? I think something could exist without an end in time, as long as it existed outside of time (ie. outside of our universe in which time applies). But then I guess that doesn't apply to the question at hand, unless you can argue that time applies within the universe but not to the universe as a whole. You probably can't argue that...

*hoping someone more competent will pick up one of these threads*

ZarathustraX
14. As yet no one had defined what they mean by bigger. The Universe has a finite amount of energy in it and if you doubled that, then the Universe would be larger than it is now. This would probably led to an open universe.

Until someone actuals defines what they are making bigger this question is completely nonsensical.
15. (Original post by technik)
surely...

n x n = ?
no as you failed to understand the concept of infinity
16. So conclusion,
i) if the universe is infinite, then you are doing infinite+infinite = infinite. =>no change.

ii) if the universe is finite, consider that the universe is expanding and and we dont experience any changes => no change.
17. (Original post by mik1a)
Like I first said it depends if you simply add another univrseon the side, or the current one is streched to double its volume.
If you "added another universe" in such a way as to make them both merge together into one, then you'd be back to "adding to infinity" (if the universe was already infinite), which leads back to my earlier point.
If you "added another universe" in such a way that really all you had was two universes next to each other, then the universe wouldn't have doubled in size anyway.

ZarathustraX
18. (Original post by Speciez99)
no as you failed to understand the concept of infinity
There is however such a thing as "big infinity".
19. (Original post by Zarathustra)
Do you mean in the temporal or extended sense? I think something could exist without an end in time, as long as it existed outside of time (ie. outside of our universe in which time applies). But then I guess that doesn't apply to the question at hand, unless you can argue that time applies within the universe but not to the universe as a whole. You probably can't argue that...

*hoping someone more competent will pick up one of these threads*

ZarathustraX
i mean in a rational sense. where you cant have something that never ends. if it doesnt end it isnt a tangible "thing"
20. (Original post by mik1a)
Like I first said it depends if you simply add another univrseon the side, or the current one is streched to double its volume.
Considering the fact the universe started off as a singularity in most theories, spatial dimensions are pretty meaningless. The universe is constantly expanding so in x time it will be so many time larger. What you surely want to change is the amount of energy the universe has and the way in which it expanded. (rate)

Updated: February 14, 2005
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