The whole subject baffles me. I don’t understand it and I don’t understand what the purpose of it would be. Don’t we have enough problems with just one?
Purpose?
Max Tegmark in the Physics department of the University of Pennsylvania seems to have done pretty wide ranging work establishing the field, though it may be later than many of the people throwing ideas around.
To oversimplify this a bit, a lot of this depends on mathematics. You do your problems and the results give you answers.
You then are presented with a choice. In this case multiple universes. Now one can simply say 'That’s wrong." And that is that, or one can continue to examine “why can’t we have it.”
That’s where the discussion starts.
It’s like when someone says “nothing moves faster than the speed of light (in a vaccum”). This seems to make no sense, why can’t it just move “a little” faster. Of course if you spend a few hours with a good physics books it does make sense, but at first glance it seems to fly in the face of common sense.
Same with multiple universes. It seems to fly in the face of common sense.
Is it real? We don’t know yet? But as long as the mathematics are not flawed we have to either disprove the math or accept it as a possiblity.
Just remember just because something is POSSIBLE doens’t mean it HAS TO be.
It all started when Barry Allen inadvertently vibrated his molecules at the frequency of a parallel universe, thereby traveling from Earth-One to Earth-Two in Flash #123 (Sept 1961).
The original purpose was to reconcile the differences between what we now regard as the Golden and Silver Ages, by establishing the premise that they constitute different universes which exist simultaneously and largely independently of each other.
This premise was later extended to include a variety of other parallels such as the morally inverted Earth-Three (home of the Crime Syndicate of America), Earth-Prime (our own reality), and Earth-C (home of Captain Carrot and his Amazing Zoo Crew).
The “Many-Worlds” interpretation in quantum mechanics basically addresses the same problem, but involves more math.
Rest assured, you are not the first to find this theory unduly intricate and unwieldy; but ultimately it is useful in addressing certain problems which can only be solved by an annual team-up between the Justice League and the Justice Society.
You win one internets, sir. And you owe me a new cup of coffee and keyboard.
To amplify the not-quite-as-awesome-cool part of Terrifel’s response, if by “theory of multiple universes” you mean the many-world interpretation of quantum mechanics, it is (well, as the previous phrase implies) an interpretation that tries to make sense of some of the counter-intuitive results of quantum mechanics. It’s probably hard to understand what is going on without knowing a little bit of quantum mechanics (do you know about Schroedinger’s cat at least?), but I could give it a shot, or you might try posting in GQ for people who explain better than I do 
There’s a Nova special, called “Parallel Worlds, Parallel Lives” about it.
The inventor of the Many Worlds Interpretation was Hugh Everett, in 1957. His son Mark Everett is the lead singer for the indie band Eels, and didn’t know much about physics or his dad. Its a very interesting program and explains the theory for the non-scientist.
Scanning down the MPSIMS thread list, I originally read the title as referring to multiple orgasms. Viewed in that light, this thread has been a disappointment.
Although … I suppose there’s a universe out there where this thread does refer to multiple orgasms.
snort
One of the simplest arguments for multiple universes is, why wouldn’t there be? We live in the evidence that a process exists that can create a universe; why would we assume that it would just stop with one?
Great. Thanks. You’ve just convinced me to be a theist. Look out GD!
:dubious: Um, why ?
What do you mean by “multiple universes?” Are you talking about just the concept in quantum mechanics or in other areas? There have been other sorts of multiple universe theories:
http://en.wikipedia.org/wiki/Multiverse_(science)
It might be traced back to the ideas of Giordano Bruno, for instance.
You know, it would help if you explain what you’re talking about in the OP rather than just throwing out a term and expecting that we know which theory you mean.
(Handing Der Trihs a Chick Tract) Well, you see, one of the simplest arguments for God, is, why wouldn’t he exist?
Because God violates physical laws? Because we have no example of a god actually existing, while we do have an example of a universe existing? Because we already know a universe is possible since we are in one, but have no evidence that a god is possible? Because God is clearly nothing but a human ego fantasy, while the universe is objectively real?
The two things are not even remotely alike.
I’m pretty sure the *literary *(not scientific) concept was invented by early fantasy writers who wanted their characters to go to places that were both very close and very far. Places like Oz, Wonderland and Neverland are all proto-parallel universes. They’re like alien planets, except you don’t have to use a spaceship to go there.
But if God created the Universe…who created God? I’d prefer to worship God’s creator, especially since God clearly has bipolar disorder.
P.S. What’s a Chick Tract?
I highly recommend this Nova episode. Mark talks to several of his Father’s colleagues, and gets them to explain the Parallel Universe Theory in such a way so he (very much NOT a physicist) can understand it.