Alternate universes are popular among science fiction and comic book writers, who frequently use them as plot devices when fanboys want to see a good character acting evil or vice versa. See also: "What If?"
To keep my overactive mind from troubling me too much, I hold my silly fantasy of alternate universes. For everything that has gone wrong in my life there is a universe where it didn't. There is a universe where my childhood dog runs through my yard and sits under the shade tree with me in the summer. There is a universe where I'm still with my first love. There is a universe where I get to be with all the people I wish I could've known more about. These alternate universes are perpetually happy. They hold those perfect moments that we experience forever. I realize this is a cheesy, sentimental idea, but sometimes it makes me feel better. It often reassures me to think that no matter what happens somewhere there is a me that lives the lives I never could.
This is a scientific theory that seeks to describe how quantum physics can function. There is also the Copenhagen Interpretation, the Hidden Variables interpretation and many others (mostly variations on the three main ideas). Many worlds is the idea that every quantum event splits the whole universe so that each possibility is played out in a daughter universe. This would be transparent to people in the universe but raises some interesting ideas.
It is this idea that gives us the idea that conscious decisions or other macro events create universes, whereas there are so many universes being created that there are a lot for each decision. It's safe to assume that there are a relatively high number of almost identical universes though (i.e. down to the position of a single photon in a single double-slit experiment 50 years ago).
Ok, imagine the universe is infinitely big and contains a lot more energy than we suspect (specifically infinite energy). As information is bound by the universal speed limit of the speed of light we can't know about anything above a certain threshold away. It's possible that the universe consists of localised centres of mass that we call the observable universe. As it's got infinite energy, there are an infinite number of these centres, so an infinite number of observable universes. As the probability of you existing is not infinitesimal there are likely to be infinite copies of you with varying amounts of congruence to your life. But then, if there's even a small difference are you the same person? Twins are different people, so arguably you're different and just very similar.
Sounds familiar, right? Two options, both with seemingly infinite universes. Except under many-worlds the number is growing, in the latter it is static. Whether many-worlds is an infinite number of worlds or merely a growing finite number depends on whether all quantum events have a finite number of outcomes or not. The granularity of spacetime seems to be the big issue here. No matter what you do you cannot split your universe. Also, you cannot visit another universe without being able to exceed c. All probabilities still play out, as there are an infinite number of worlds currently identical to yours that will later diverge.
God I hate infinite numbers.
As the above explanation of many-worlds, if you can leave your own universe you'll have a very difficult time getting back as there'll be more than one version of you and more than one home-world. Not only might there be a difference in numbers, but getting exactly one version of you per universe would be a logistical nightmare.
Everyone knows this plot line, there's an alternate universe with all the same characters who have completely different personal histories, not to mention the huge political differences in the whole galaxy. If our whole civilisation was changed hundreds of years ago we wouldn't be here. People would be, but they'd have different ancestors. Even if we did have the same ancestors, which has such a small chance it's not worth considering, unless the exact same sperm/egg pair met we'd have significant differences. Just look at non-identical twins.
Well, nobody knows! Personally I lean towards the hidden variables idea ("God doesn't play dice" and all) but Copenhagen seems more likely than many-worlds. If you really believe in many-worlds you can prove it to yourself, but I really wouldn't recommend it. Basically, hook up a gun to a quantum random number generator and run it until there's a million-to-one chance of surviving. If you experience life for much longer chances are you're in one of a very small number of worlds in a many-worlds universe.
If you want to talk about multiple universes, feel free, but remember than a huge number of scientists prefer the Copenhagen interpretation which doesn't automatically means there are multiple universes.
Maybe I shouldn't have watched that episode of sliders today.
I don't know how big this Universe -- the one we inhabit right now -- is, but assuming it's really, really big so that it can be considered more or less infinite, extending an uncountable number of units in any given direction from any given point, then the whole idea of alternate universes could all exist without lots and lots of other universes.
Our existence is governed by a finite improbability. The fact that I'm typing here is due to the tiniest chance that the earth was formed, and from that, the tiniest chance that life developed, and the tiniest chance that life developed into an intelligent species that invented the Internet. But the fact remains that it's obviously possible for it to happen, because I'm witnessing the results of it happening.
But if the Universe is (or is nearly) infinite, then if we take that teeny-tiny chance, one in a bajillion, and multiply it across the countless stars and planets in the Universe, shouldn't exactly what happened on our planet have happened somewhere else? And moreover, shouldn't there be worlds that are almost exactly the same only different in some respects? Entire galaxies exactly identical to others, or even, entire "observable Universe"s that are exactly or nearly identical, because of what happens if you multiply a really small chance by enough trials?
Taking it a step further, if we believe in the whole quantum mechanics, Schroedinger's cat thing, where time and space must exist in two states at once, until they are observed, and upon observing them, we create and decide their outcomes, if the Universe, just this one, not even taking into account the possibility of alternate ones, is big enough, and there are enough trials, there must be at least two scientists doing the same experiment. And not only would both outcomes (I'm using the cat in a box idea, because it works) occur, there should be an infinite number of dead cats, and an infinite number of living cats, because of how massively big the Universe is. Therefore, it doesn't matter how your cat turned out, because chances are somewhere else someone else's cat is alive.
The point is, if the Universe is infinite, if it's really as massively big as they say it is, then the entirety of the theories of alternate Universes and how they're created is a moot point, since whether or not you created an entire observable Universe based on taking one elevator or another, chances are, another, exactly identical one exists only, in that one, you took the wrong elevator. If the Universe is infinite, there should be an infinite number of you, or people who are exactly like you, who have taken every possible elevator in existence. Infinity is scary.
printable version chaos
Everything2 Help
