Posted on 08/03/2006 12:52:54 PM PDT by PatrickHenry
Our universe (and there may well be many more universes besides our own) isn't infinite, but there also isn't anything "outside" the universe - the universe is defined as space itself, but space itself has been expanding since the Big Bang. There's no "empty space" outside the universe it's expanding into, though.
I realize it all makes your brain hurt...try reading any of the books from Brian Greene or Michio Kaku.
There may be other universes, but by "the universe" astronomers and physicists mean all the matter (and the space it occupies) that we will ever be able to see, know about or communicate with. According to our current understanding of the laws of nature, if other universes exist there is no way for light, or anything else, to travel from them to us, or any part of our universe, or we to them.
It is a consequence of the theory of General Relativity that our Universe is finite, but it does not exclude the possibility of other universes.
Good thing I filled up before I left town!
For what it's worth, the age of the universe during Einstein's time was 1.5 billion years. Now it is ten times that.
I hope they get a lot more data points.
The reason it makes your brain hurt is that it does't make sense. Space is space. Nothingness is space too. Why can't the scientists just use the magic words: "I DON'T KNOW!"?
This makes more sense, explained this way.
Here is what you are missing. According to Greene, mentioned above, the radius of the universe is 25 billion times bigger than the Hubble radius. The Hubble radius is as far as the Hubble telescope can see, which is nearly all the universe that can ever be seen since the rest of it is leaving us faster than the speed of light. That is, we can see a grain of sand and take that for the entire earth--similar relative scale.
By two years, at least.
Any such "other" universes would have to be strictly orthogonal to our own (no interaction allowed). If you can in any way sense or detect another universe then it's not another universe, it's more of this one.
Which means that there can be no provable nor useful science about "other universes". Any observation of another universe is - by definition - not an observation of another universe.
We should probably stop throwing these loose Star-Trek tropes around IMO. "Parallel Universes", "Alternate Universes" etc - they're fine if you're a lazy SciFi writer and want a quick plot line about evil Spock or a leather-clad Intendant Kira (Freepers will know the DS9 episode I mean!) but they're appalling science.
It can be so red shifted as to be very hard to observe.
This could be very bad news for the universe
Why not? Is that what they told you?
Hmmm...this seems to not be news. Bonanos, Stanek, et al.'s estimate is 61 km per second per million parsecs.
http://csep10.phys.utk.edu/astr162/lect/cosmology/hubble_constant.html
has it between 50 and 100.
There's an interesting essay by Isaac Asimov -- "The Proton-Reckoner" -- published in 1966 -- Hubble's constant was thought to lie between 75 and 175. Asimov takes the lower limit of 75 and calculates an observable universe of radius equal to 13 billion light years. A value of 50 would indicate an observable universe equal to 20 billion light years.
Actually, GR sort of does exclude other universes. It works like this: the laws of our universe are 'balanced' (defined) by the conditions of our universe, thus our particular space and time are fundamental to the definitions of the laws, but prior to the big bang there is no space and time, so ours is the only universe of reality related to space and time ... IOW, it is impossible to experiment or produce data to verify the existence of other universes. Now if you mean to say branes instead of 'other universes' you may have a point there.
No, the universe is definitely finite, though the 'radius' of a 15 billion year old universe might be 40+ billion years thus the horizon is beyond our ever getting information from it. For all we know, the whole 'shebang' may be contracting at some where/when out beyond our information horizon, and in a few million or billion years, we'll be 'incorporated' in the 'renormalization' (collapse).
And...when was it that "they" removed your brain?
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.