Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: thedoc on 23/09/2012 19:30:01
-
CATHERINE asked the Naked Scientists:
Could parallel universes exist? Is there any evidence for them?
What do you think?
-
There's actually evidence for them.
If you do the twin slit experiment you find that the photon has gone through both slits.
The theory is that there's essentially two different universes that split off ours, and the photons in each universe both ended up in the same place, and then the universes joined back together again. You can see that this has happened in the statistics when you do the experiment.
What we don't know for sure is what happens to the photons in the two universes when they don't end up at the same place; perhaps they never existed if they weren't going to join up, but it's impossible to see how they would know that. Or else perhaps they got pruned somehow, or perhaps they're still out there in their parallel universes diverging from ours, and thus unable to join back again. This actually seems to be the simplest idea since we don't know of anything that would prune it.
So this is actually evidence for parallel universes, but it stops short of proof.
-
Parallel universes are absolutely unnecessary to explain the double slit experiment. The photons interact as particles but they move as waves. It is possible that there is parallel universe but it is unlikely. Everything can be explained without them.
-
Well, Hawking has stated that parallel universes are a trivial consequence if the universe has a state that is described by a quantum mechanical wavefunction, and that kind of wavefunction is consistent with the dual slit experiment.
-
This is only an interpretation where you need many worlds to conserve causality (probabilistic universe). This is an ancient idea if you want my opinion. The pilot wave theory does not need it. But science-fiction is a best seller...
-
Although many mainstream physicists believe in some sort of multiverse theory, there is no single mainstream theory of multiple universes. They all should be discussed in the New Theories forum, regardless of which reputable physicist or cosmologist believes in them.
There is some disagreement on the meaning of "universe". Is it everything that exists? If it can have no effect on us, does that mean it doesn't exist for us? If it doesn't exist for us, does it exist at all? Does my imagination exist? Is it part of the universe? If I imagine another universe, does that become part of this universe? Did that other universe exist before I imagined it? I'm getting out of the realm of science and into the realm of philosophy.
If something happens in another universe, it cannot be directly observed from this universe. We can only speculate the the other universe exists because it helps to make sense of what we observe in our universe. It may help to resolve apparent paradoxes.
If we ever do directly observe something from another universe, it will no longer be another universe. We will have to redefine our universe to be more inclusive.
-
This is only an interpretation where you need many worlds to conserve causality (probabilistic universe). This is an ancient idea if you want my opinion. The pilot wave theory does not need it. But science-fiction is a best seller...
The existence of pilot waves is an extra assumption, that has no particular experimental support. The existence of parallel universes is not an extra assumption, as Hawking says, it's built into QM theory unless you add extra assumptions (quantum wavefunction collapse being another way).
-
Not to pick a fight with Hawking, but isn't the existence of parallel universes an extra assumption above and beyond the math? The math doesn't say anything about additional universes, just what the result of measurements is. In fact, the multi-universe interpretations of the math were developed to match the theory, so the fact that theory (or experiment) agrees with them isn't really evidence that they're correct, is it?
This is why, I thought, the Copenhagen interpretation was the most widely accepted, while the others introduce extra complexity.
(I say this, by the way, as someone who prefers the many-worlds interpretation...)
-
Parallel universes was the simplest way to make the Copenhagen interpretation causal by adding all possibilities in many worlds. This is in fact a total lack of imagination and laziness. The Copenhagen interpretation is telling you to stop to think, you are not allowed to ask, the world is probabilistic!!! No way!!! Einstein was right! The world is not probabilistic, although experimentally it is. See my theory:
http://www.thenakedscientists.com/forum/index.php?topic=34413.175
-
sorry JP, i didn't read your post before posting myself. You shouldn't hide my post though. Just cut my link if it is in disagreement with the rules...?
I have nothing against Hawking, in the contrary.
-
Not to pick a fight with Hawking, but isn't the existence of parallel universes an extra assumption above and beyond the math?
No, it's the other way around, you have to add an assumption to get rid of them, like pilot waves, wavefunction collapse.
The math doesn't say anything about additional universes, just what the result of measurements is. In fact, the multi-universe interpretations of the math were developed to match the theory, so the fact that theory (or experiment) agrees with them isn't really evidence that they're correct, is it?
We know that we have many universes looking backwards in time, 'many histories'. That's really the standard model, like in dual slits it went through BOTH slits, so in that sense at the very least, there's parallel universes, 100% definitely.
This is why, I thought, the Copenhagen interpretation was the most widely accepted, while the others introduce extra complexity.
No, the 'wavefunction collapse' that there can be only one, is an extra assumption.
-
sorry JP, i didn't read your post before posting myself. You shouldn't hide my post though. Just cut my link if it is in disagreement with the rules...?
I have nothing against Hawking, in the contrary.
Interesting, can you provide that link? if you can't here due to rules, send me a personal message, thank you.
PS: I'm saving all my replies because some of it, were deleted.
-
sorry JP, i didn't read your post before posting myself. You shouldn't hide my post though. Just cut my link if it is in disagreement with the rules...?
I have nothing against Hawking, in the contrary.
Sorry, CPT ArkAngel. The new "shrink post" feature renders them unreadable. I shrank your post because I judged it to be essentially an attack on science advertising your new theory.
If you'd like to put the link back up with a note that you have an alternative explanation (without being so aggressive against science's explanation), that's fine.
-
Not to pick a fight with Hawking, but isn't the existence of parallel universes an extra assumption above and beyond the math?
No, it's the other way around, you have to add an assumption to get rid of them, like pilot waves, wavefunction collapse.
I think we just fell down this rabbit hole in a couple of threads about SR lately. The math of the theory says nothing at all about extra dimensions. It's an added assumption, just like wavefunction collapse, if you believe wavefunctions are a real thing that are actually collapsing.
The math just tells you that somehow a particle goes from being described mathematically as a superposition of states to suddenly being in one state when you take a measurement. How you interpret this (wavefunction collapse, many-worlds, pilot waves) is an entirely different matter and not scientifically testable.
-
You might consider the 'many worlds' scenario from several points of view. One is the pearl-bands of universes consisting of probabilities that 'splits' in ones measurement, leaving for me just the one observable, with those others that I never will see, as their probabilities disappeared for me in the outcome of my observation existing 'somewhere else'. In a way it is a very comforting universe as we all somewhere got all we wanted, probably that is :) Using 'locality' each observation made is unique too, and the descriptions you use will never be mine. There we also could consider 'splits' but now with a common nominator, radiation (and uniform motion), unifying our direct observations/experiments into 'one picture'. But it also has to do with those dar*d 'degrees of freedom' aka 'dimensions'. Because defining it so, what would those degrees of freedom mean, as we all have a different universe to observe?