You’re making an observation, and that causes the waveform to collapse.
Sources of the “parallel universe” idea?
How about “A Christmas Carol”–Scrooge apparently has a chance to alter his future, thus relegated the “former future” to some kind of parallel-universe mode.
The first more or less explicit parallel universe fictional treatment might be a novel by H. G. Wells, entitled MEN LIKE GODS. (Written in the 20’s.) British “types” are “rotated” into what is apparently an alternate earth (a Wellsian socialist utopia) by a device being tested by the other-earthlings.
But most of us probably were exposed to the concept via two or three episodes of THE TWILIGHT ZONE; “Mirror, Mirror” on the classic STAR TREK; and frequent use in comic books during the 60’s.
Parallel universe receive a formal philsophical treatment in a book titled ON THE PLURALITY OF WORLDS by David Lewis.
You mean, somewhere, sometime, someplace (outside this universe, of course), I could be dating Penelope Cruz?!!
Woohoo!
Wouldn’t this depend on how recently whatever universe you exist in broke off from the one you are now visiting? I think that your loved ones could just order a “new you” from the universe(s) that split off because of the decision/action you made that got you killed. Then you would be exactly the same as before, except you looked before crossing the street.
I’m home now. Nicholls and Clute’s Encyclopedia of Science Fiction has almost three columns on “Parallel Worlds”. Th earliest examples cited are J.H. Rosny’s “Un Autre Monde” (1895) and H.G. Wells’s “The Strange Case of Davidson’s Eyes” (also 1895) and “The Plattner Story” (1896). I have to agree that “A Christmas Caol” carries much of the Parallel World baggage, though.
The article also notes that the hazards of trading between parallel worlds are examined in Clifford D. Simak’s “Dusty zebra” (1954), and in Alan E,. Nourse’s “Tiger by the Tail” (1951).
I always like the alternate universe theory and think that Heinlein gave it excellent treatment in his last triology, starting with Number of the Beast where there are 3 dimensions of time to go along with the 3 dimensions of space.
oemama24_98
You mean, somewhere, sometime, someplace (outside this universe, of course), I could be dating Penelope Cruz?!!
Woohoo!
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Somewhere, sometime, someplace you could be dating Homer Simpson.
Disclaimer: IANAPhilosopher.
But then wouldn’t the new you disappear from the universe you were ordered from, thus the loved ones in the universe you just came from would need a “different” you to replace the one that just left for the universe that you died in…and then they’d order a new you, and so on. There’d always be one less of you than is needed to replace you in a universe that you died in, or disappeared from.
What you need to do is borrow a new “you” from one of the universes where “you” are still alive and move him to another universe with “you” alive, then make a quantum decision, splitting that universe in two. Now you’ve got four "you"s; one goes back to the universe you borrowed a “you” from, one to the universe of the deceased “you”, and two stay in the now split universe. Simple. 
Hey, its just a vacation…everybody goes back to their original reality.
Although this does bring up the notion of trans-reality
visas, illegal aliens, immigration & naturalization, fugitives, refugees, and other technicalities arising from the interaction of visitors with natives.
Having just discussed this in my GR class, I think I should add…
It is possible to use gravitational effects to travel backward in time. This is where we get into so-called “causation” paradoxes. If and when someone goes back in time either via wormhole or via whipping around two cosmic strings, the person will be able to return to the point at which she left. Then she will be able to determine unequivocally whether the universe is internally consistent with respect to time. If not, parallel universes here we come. If so, well, then, there’s another white ball in the box for the conservative theory (which is basically a deterministic materialism, if you ask me… but you didn’t).
Note that just because you go back and suddenly realize that you cannot kill your grandmother (for whatever reason) does not mean that parallel universes don’t exist. It might only mean that time-travel is not a way to get to them… but since causality is semi-important to discussions of quantum philosophy, we may have more on our hands than just that.