This is the best reply ever! It explains ‘the known universe’ AND it’s edge! Thanks, guy.
Tyrrell McAllister, dude-- I’m the person who called the Arcminute Cosmology Bolometer Array Receiver (had to look it up) a whoziwhatsit. This is also not the first time I called an astronomer an astrologist. You’d think I’d learn.
That’s ok, because I lied when I said I don’t like to nitpick :D.
As it has been explained to me there is no edge, merely a limit beyond which we cannot see, sort of like a horizon.
The pretty-well-known-by-now expansion rate shows that the further away things are from us the faster they are receding from us. It turns out that by the time you get out about 14.5 billion light years their recession velocity is the speed of light. Even if there were more universe out there we can never see it because it would be ouside our light cone.
I notice that Pochacco beat me to it, but to hell with it.
This is a total hijack, but I’m trying to figure out Tyrrell’s location. In English, it says, “x is an element of set S if and only if x is not equal to itself.” I don’t get it. Is it a reference to Russell’s Paradox? Are you from Essex? Maybe you had backwards sex with your ex and it ended in distress?
Despite a few minor disagreements, this is not so much a debate as a General Question. You might get even more good answers from the GQ denizens who choose to avoid GD.
Off to GQ.
There’s something about this question that disturbs me. You’re implying that the universe and its age and its size must conform to your own subjective preconceptions, that if we believe that the universe is *merely * 16 billion years old, then someone’s made a mistake. The universe’s age is what it is, regardless of your expectations. Of couse, in the future, we may have to revise our estimate, but it still has nothing to do with your feelings on the subject.
Suppose you’re standing in NYC, and someone tells you that San Francisco is almost three thousand miles away, and you reply, “That number is waaaaay too small for me. . . . There have got to be theories that make that distance much, much larger than three thousand miles.”
Just a little thought that I thought was neat.
I was watching one of them, “Tell us about the universe.” shows and Hawking was giving snippets and someone asked him what was beyond the edge of the universe. He replied with something like, “Why does there have to be anything beyond the edge?”
There ARE other theories out there that explain the universe differently than does the Big Bang. There are not other theories of measuring the distance from NY to SF, however.
Having said that-- of course the consensus of today’s leading scientists is what we know as ‘true’ today. However, less than 20 years ago, the leading scientists and mathematicians postulated the the universe was 3 or 4 billion years old. And that was wrong because we know that Earth is older than that. Hell, up until Hubble the leading scientist thought the Milky Way was the whole universe. When such great minds as Einstein and Hoyle felt uncomfortable with such a young universe, I don’t feel ill at ease stating the same.
IIRC an open universe that will expand forever, like ours is presently believed to be, is supposed to be infinite.
WAGs about the size of the entire Universe are a dime a dozen. There aren’t really any SWAGs, though. We know it’s bigger than what we can see, and that’s about all we know. It may or may not be infinite.
As for the age of the Universe, we think we’ve got that down pretty well, now. As recently as a decade ago, estimates of the age varied by a factor of two or more, and the best guess for the age of the Universe was shorter than the best guess for the age of the oldest stars. Great leaps and bounds have been made recently in astronomy, astrophysics, and cosmology, though, and we now have three or four completely independent lines of inquiry which all point at approximately the same age. Most notably, the Hubble Capstone Project, which measured distant supernovae, and the data from the Microwave Anisotropy Probe, which looked at the relic radiation from when the entire Universe was very hot, both agree to rather high precision.
Do we even know this? It’s possible that the radius of the universe is smaller than our observation range and we’re seeing the same distant galaxies “wrapped around” from one side of the universe to the other.
You may find this interesting: If the universe is infinite now, then it has always been infinite, even one gadzillionth of a pico second after the big bang.
I’d love to hear more on this.
It sounds more like an abstraction caused by human number system than a physical fact.
Can you explain?
I don’t think so. Infinite means, well, forever. There is no one gadzillionth of a pico second after infinity. There is no after, there is no before.
http://www.astro.washington.edu/bbeck/201/summaries/lecture/062696.html
If the Universe is infinite/finite now, it has always been infinite/finite. The critical density is decreasing with time.
http://ezra.cornell.edu/posting.php?timestamp=1026964800
In an open-infinite universe, 3-d space has ALWAYS been infinite, even at the ‘birth’ of the universe at the Big Bang.
http://www.astro.washington.edu/bbeck/201/summaries/section/062096.html
Furthermore, if it is infinite now, it has always been infinite, even immediately after the Big Bang.
If you still don’t think so I can probably find an infinite number of other cites. And yes these cites also existed at the time of the big bang. 
Sorry I didn’t see your question before.
I’m no cosmologist, but I can’t imagine how it would be possible for something to go from being finite to being infinite without an infinite amount of time passing.
Astronomers have considered this notion and firmly rejected it through observations.
I know i am going to get ass raped for this… however… this particular type of question is what makes me believe in the existence of a higher being. The deeper I delve into science… the more i am convinced that none of this could possibly be random. Now this is MY feeling and im not arguing anyone else’s feelings. But damn people there is so much we dont know. Sure in the future we will figure more things out… but i bet they only lead to more questions. Do you think there will be a one sentence answer at the end of all the questions? I do.
Biggirl writes:
> However, less than 20 years ago, the leading scientists and mathematicians
> postulated the the universe was 3 or 4 billion years old.
No, they didn’t. If anything, the standard estimate of the age of the universe was greater about twenty years ago. It was about 15 to 20 billion years, less accurate but slightly greater than the present estimate. I don’t know when scientists estimated the age of the universe as 3 to 4 billion years old, but it was more than forty years ago. I just checked a book published forty years ago and the standard estimate then was apparently 8 to 10 billion years old.