That quantum physics theory that holds that, in essence, any time you bite into a McDonalds burger, one "you" contracts food poisoning and dies, and another "you" survives to take another bite. -- JonGreen

The above is not accurate since it gives human-level decisions undue emphasis (exactly what the theory tries to avoid) but it's close enough. It's better known under ManyWorldsInterpretation since "Many-Universes" could refer to, say, Andrei Linde's cosmic foam theory.

----

Anyone know of more background on why this is viable? I love it, don't get me wrong. It's fun MindCandy, much better than "one hand clapping". However, it's got me curious: what is the scientific/observable basis?

I'm fine with an answer that says, "Aww, you need to know a bunch of stuff before it would even start to make sense," so long as it comes with some pointers to where I can learn a bunch of stuff from. Thanks!

''Briefly the reason why many worlds is viable is that it is what you get if you believe that human beings can be modelled as a quantum mechanical system. For instance in SchroedingersCat before we open the box the cat is both alive and dead. After we open it the cat is STILL both alive and dead - and we both saw it alive and saw it dead! There are 2 copies of us that observed different things which cannot (for understood thermodynamic reasons) manage to tell each other that, "Hey you! I didn't see what you did!"''

''In other words many worlds is Alexander's solution to the Gordian knot of observation. Everett asked why we need to assume that collapse happens upon observation, and found that there is absolutely no reason (other than human prejudice) to believe that it does. The many worlds interpretation is the result.''

''(For far fuller explanations see the links elsewhere on the page.)''

''-- BenTilly''

'''''NOOOO!''' Seeing this nonsense repeated really, really hurts. The cat is NOT both dead and alive as long as the box is not opened. The superposition collapsed way before that instant through interaction with the environment, there is NO half-dead cat to be seen and seeing it doesn't cause any mystical collapse or the splitting of the universe in two.

----

There is a very extensive FAQ at:

http://www.hedweb.com/everett/everett.htm

In particular, see Q36, claiming that Many-Worlds theory makes some unique predications (and would therefore classify as a scientific theory/hypothesis according to Popper).

Or try http://www.station1.net/DouglasJones/many.htm.

''But be careful with the FAQ - it takes a very aggressive line in claiming that there are no alternative scientific interpretations. Don't take Q3's word for it - check out the TransactionalInterpretationOfQuantumMechanics at http://mist.npl.washington.edu/npl/int_rep/tiqm/TI_toc.html to see at least one logically satisfying and potentially testable alternative.''
----
CategoryPhysics