Parallel Universes

[Rhovineth]

I think this is the right forum for this (it looks like the least wrong one ...)

I'm not too familiar with quantum physics but I've read John and Mary Gribbins' "The science of HDM" which gives a good accessible overview. I still have a question though. The people who talk of parallel universes also talk about universes of twelve dimensions. Does this mean parallel universes exist in different dimensions?

If they don't ... then surely they are part of our universe? But if they do ... they must be pretty odd places not near replicas of Earth? I suspect this dilemma is just another case of logic leading someone astray, but I can't see a way out of it.

Can anyone enlighten me?

[Gabe]

Well (going with string theory), you have the three dimensions of space and one of time, but also several other dimensions...since they don't seem particularly noticeable, they're thought to be very small. The four dimensions we are well aware of may actually be looped. From a distance the loop appears to be just one dimension (like a tube when viewed from a distance appears to only have length) but on closer inspection there's another smaller dimension...that is, the circumference of the tube.

As far as multiple universes, however, the ones predicted by quantum mechanics are like our universe...that is, they aren't things that exist in other dimensions of our universe, they are completely separate universes (complete with dimensions and physics just like ours) that are just kinda floating out there next to ours. There is an infinite number of them where everything happens...every possible thing that could happen, happens in one of those universes (which means many of them are nearly identical to ours, and most are completely different).

Then of course you also have the ones in string theory where actual physics can be completely different...really freaky stuff there.

Really, HDM's universes are so connected and similar they're not exactly separate universes at all... *cough*

[Ian]

Really, HDM's universes are so connected and similar they're not exactly separate universes at all... *cough*

So are all the universes which are parallel, actually sort of hanging there in one big universe for all the other universes? (sorry if this is stupid question, but I don't really get physics)

[Gabe]

So are all the universes which are parallel, actually sort of hanging there in one big universe for all the other universes? (sorry if this is stupid question, but I don't really get physics)

Erm, well HDM's universes were kinda made up by PP using actual multiple universe theories for inspiration...there's a big long thing I could go into, but er...I'm tired right at the moment. basically though, for the moment forget about HDM's universes because they muddle things up a bit (though it can be straightened out so it's all fine).

Think of a universe as a sphere...this contains everything in our universe (even though the universe may be infinite...you have to remember that imagining it as a sphere is not a literal representation of what the universe really is, since it obviously has a lot more dimensions...the point is that it's all blobbed together). Other universes (where you have things happen differently) are other spheres...they're just kind of out there...there's no space outside of the universes, so they're not exactly really next to each other, but it's easier to think of it that way. So all the universes are all just sort of out there in nothing...they aren't in anything.

HDM universes don't work like that, however, which makes a bit of a sticky situation (yeah right...quite convenient actually )...they're too connected and there has to be a finite number...they can't satisfy quantum mechanics. In other words, these are not the universes we're looking for...move along, move along. *Falls asleep*

[Huginn]

HDM universes don't work like that, however, which makes a bit of a sticky situation (yeah right...quite convenient actually )...they're too connected and there has to be a finite number...they can't satisfy quantum mechanics. In other words, these are not the universes we're looking for...move along, move along. *Falls asleep*

I could quibble with this: I think the closest multiverse model that fits HDM would be a classic level 1 multiverse, in which separate universes are just different arrangements of the same amount of matter/energy. In this scenario, there could be infinitely many universes, but since there is only a finite number of ways to arrange the stuff in the universe at any given time, the universes must repeat after a while, ensuring that there is a double of each universe (and more, of course).

However, the travel between universes exhibited in HDM would upset this fragile balance, which makes me lean toward something more complex...perhaps some kind of travel through the 11th dimension, akin to the bleed-through of gravity that is already suspected (though this is all highly speculative).

[lirael]

i don't know much if anything about quantum physics but i have a kind of theory for parallel universes.

here goes

in our universe there are countless other universes co-existing but no of them are exactly the same, and millions more come in to existence all the time because they are formed by decisions i.e if one person makes a decision to walk to work but they have they choice of driving a parallel universe is made where they take the second option as apposed to the first and because they are identical up until on point they exist almost in the same place in time and space.

well thats my theory for whats its worth. and it might work for the books.

[krebbe]

i don't know much if anything about quantum physics but i have a kind of theory for parallel universes.

Then it's a belief, not a theory.

[Rhovineth]

Thanks, all! I'm much clearer about that now. Universes are compartmentalised off from each other, not because they are in different dimensions, but because they simply are different universes. They appear to human eyes to be largely composed of the same dimensions as ours. They have the extra dimensions, as has ours, they're just not readily apparent.

I asked because I'm working on a "conworld" constructed world as a setting for an imaginary language [uh, huh ...] and want the world to be in a parallel universe. I'm putting the whole thing on a website and want the physics to be right!

Actually, the physics is (are?) a bit speculative too. Like Huginn, I'm saying travel between universes is possible using the 11th dimension and like Lirael says I'm saying universes branch off from each other as different choices are made.