Over the weekend, I was flipping channels and caught about 15 minutes of some documentary program on The History Channel (I don’t know what it was called – maybe “The Universe” or something).
The program was on the theory of parallel universes, either within or apart from our existing universe. The idea was that IF the universe(s) is/are infinite, then everthing that is physically possible to occur has occurred, or is occurring somewhere. So, somewhere in the universe/multiverse, there exists an exact replica of earth except there is ocean where Rhode Island should be. Or somewhere there exists an exact replica of earth, but intelligent life evolved from salamanders. Or somewhere there exists an exact replica of earth, and all of human history is exactly the same as it is here, except my counterpart just lifted his left arm up, whereas I just lifted my right arm up (trust me).
You see where I’m going with this. It just seems…loony.
Since this is general questions, not GD, here are my questions relate to the existence of this theory, rather than whether or not the theory is correct.
Did I get the gist of it right? I realize this would be much easier to answer if you had actually seen the same History Channel program (which some of you may have), but if not, does this sound like an actual theory?
If so, do intelligent, scientific-type people actually believe this? They did have talking heads in the documentary, but I missed if they were identified as professors, researchers, or former “Star Trek” writers.
If (1) and (2), can anyone recommend any good books on the subject? While I do find it loony, I also find it hard to stop thinking about.
As I understand it, that’s the gist of it, but it’s an over-simplification. I believe the actual theory is that at the quantum level everything that can have two outcomes actually generates separate alternate universes, one for each outcome. As I understand it, it resolves, among other things, the Schrödinger’s cat paradox (?) by stating that the cat is both alive and dead in alternate universes, but you don’t know which universe you’re in until you look.
Before we go any further, let’s get one key question out of the way: Can something be said to “exist” if there’s no way it could possibly have any effect whatsoever on you, nor you on it?
This reminds me of Zeno’s Paradox which, while seemingly rational in theory, does not pan out in reality.
Supposing that the universe is infinite, then there is also a chance that there’s a universe out there that remains unchanged for its entire history, since that is possible. That totally contradicts a universe where everything is different, because for every attempt at a different universe, there exists the possibility that the stable universe IS the unstable one. When one ponders infinities, the only infinite thing is confusion
Your understanding is mostly correct. It is scientific in the sense that it’s taking what we currently understand to the extreme logical conclusion. It’s unlikely that the exact shape of RI would be carved out, with it’s square borders and all. So that universe probably doesn’t exist. Neither is there one where Kansas is all ocean. But there could be ones where Florida is an island.
Read some of Greg Egan’s books and short stories. Right now, I’m finishing Neal Stephenson’s Anathem, which is essentially Egan’s Quarantine, only it takes longer to get the quantum stuff.
Yes, although I believe that the Copenhagen Interpretation is still the most accepted explanation (who said science doesn’t involve consensus.)
If one can accept the notion that Creation is ultimately random then it’s not such a broad leap to believe in the infinite number of worlds. The universe that we currently take for granted would have boggled Galileo with its immenseness.
Another way people can view this is: can something exist if there is no way to prove whether it exists? The current MWI theories indicate that there is no experiment possible where the outcome is dependent on other universes.
Zeno’s Paradox seems a rational extrapolation of simple math equations, but when applied to the real world, it falls apart. Just as in math we can have negative numbers, but in real life, we can’t have negative distance or in math imaginary number i but no equivalent in reality.
What I tried to explain in that second paragraph was that though it is mathematically possible to have infinite variations within an infinite universe, if you applied that to real life, things just don’t work out that way. If you could have infinite universes, then by definition we can have a completely stable and unchanging universe, occupying space x, for example, and a completely unstable and chaotic universe occupying space y. However, nothing makes it impossible to have both universes occupying the same space z, but in that case, it would logically rule out both. In math, they can exist, but in real life, they cannot
To be clear, here, the OP isn’t asking about the Many Worlds interpretation of quantum mechanics, but rather about locations in our own Universe, which are just unimaginably distant. You don’t need any particular interpretation of quantum mechanics (or even quantum mechanics at all) to get those.
Of course something makes it impossible to have both of those universes occupying the same space: The fact that they’re two different universes. That’s like saying that you and I can’t logically both exist, because there’s nothing stopping us from being in the same place, but we’re not.
The problem with Zeno’s paradox isn’t that math crumbles when applied to the real world; the problem with Zeno’s paradox is that its reasoning isn’t even mathematically sound.
Negative numbers and imaginary numbers correspond to reality just as well as positive numbers; you’re just picking the wrong correspondences.
No doubt you are familiar with the technique of using positive numbers to represent distance along a single axis in one direction and negative numbers to represent distance in the opposite direction, so I find it very odd that you dismiss negative numbers as having no equivalent in reality. Sure, you might say “Well, that’s really just a positive number with a little tag on it saying ‘I’m in the other direction’”, but what else is a negative number anyway? (In the same vein, we can naturally use negative numbers to describe changes in distance over time, and so forth)
As for complex numbers, the most immediate correspondence they have is to quantities which combine rotation and scaling (an angle and an amplitude). Making a 90 degree turn would then correspond to i, and the fact that i^2 = -1 is nothing more than the fact that turning 90 degrees in the same direction twice is the same as turning around. (In the same vein, we can naturally use i to describe the difference between two waves of the same amplitude but out of sync by 1/4 of their period and so forth)
If, indeed the Universe is infinite, in fact not only will there be a duplicate of you that just raised his left hand, but also an exact duplicate of you, mimicking your every move, every thought, etc. I.e., if you go far enough away, every possibility has occurred, so the possibilities start repeating themselves.
Anyway, listen to the episode; I think you’ll find it fascinating.
I haven’t read about any multiple universe theories, but on the face of it I’m not quite convinced that an infinite number of universes means an inifinite number of possibilities. Is this due to the probabilistic nature of quantum mechanics? Consider the set of natural numbers {1,2,3,…}, there are an inifinite number of elements there, but not every number is represented. 1/2, for instance, is not there.
I’m a bit over my head here, but I believe this conjecture is false if we assume that these other universes are simply a part of a large three (or 11 or 12 or more but finite number of) dimension space that has been causally separated from our portion by inflation. I believe this is the theory proposed.
The cardinality of any finite dimensional space is the same as the cardinality of the number of points on a line (or the real numbers). This cardinality is usually denoted aleph-one. Therefore there cannot be “more than” aleph-one separate universes in this type of multiverse.
But it would seem to me that the description of different universes you are describing must have a large cardinality. The cardinality of the number of curves is aleph-two. So right there we have more borders of Rhode Island than we can fit.
However another way to describe this, I think, is assume there are a finite number n of types of elementary particles (including excited states and the null elementary particle for vacuum). Then each point of space can be in one of n states so there are Aleph-one^n different universes. But aleph-one^n = aleph-one .
Sure. Think of it this way; imagine that there is indeed another universe, with intelligent life, that can never affect us. Now, imagine that some creature in that universe asks the same question you have. Clearly, the answer is yes - we are here, regardless of the opinion of an extrauniversal alien. And by the same token, they exist whether or not we will ever know of them or believe in them.
Meh. I don’t think the OP’s proposition has been stated formally enough for us to really be dragging in discussions of cardinality, but here’s my pedantic response anyway:
You’ve made a slight but common notational mistake: The number of points on a line is usually denoted beth_1 (or 2^{aleph_0}, or simply c). The proposition that beth_1 is equal to aleph_1 is known as the Continuum Hypothesis; it is neither provable nor disprovable from the standard foundational axioms of set theory, though most who would say there is some Platonic truth to the matter feel that beth_1 is much, much larger than aleph_1.
Depends on what you mean by curves. E.g., if we are talking about arbitrary functions from angles to radii, or similar things, then there are indeed beth_2 many of these. But if we restrict ourselves to continuous ones, then there are only beth_1 many of these, and there is no immediate difficulty.
You’re a little off on that calculation; if each point can be in one of n many states, and there are K many points, then there are n^K many configurations, not K^n. And n^K > K whenever n > 1, even in the transfinite case. So this is indeed a stumbling block to having every possible configuration of the entire universe actually realized as some subuniverse of it. But is that really what was being proposed? I took the OP to merely be saying something like “Every possible 1 meter cube is realized somewhere within the universe”, which cannot be defeated by cardinality arguments.
Well, your first supposition is begging the question: Chronos is asking something like whether it’s meaningful to even imagine there is indeed another universe, with intelligent life, that can never affect us. If one was skeptical about this to begin with, then it would be like trying to imagine a four-sided triangle.