Multiverse theory incompatability

[Faradaympp]

Ok, assuming that multiverse theory is correct and there are a plethora of alternate universes out there each with their own potentially different physical laws. Is a universe that is incompatible with multivese theory possible?

[DropLogic]

I think Hack can take this one...

[Inevitable Droid]

I think Hack can take this one...

[hackenslash]

Short answer, no. Long answer, there can be no such thing as a universe that is incompatible with multiverse theory, because multiverse theory allows for every constant to be variable to some degree. Indeed, some of these hypotheses have been erected precisely to explain away the anthropic principle.

Much longer answer:

I really detest the word 'multiverse' and I even more detest the discussion of 'universes' plural, because there is and can only ever be one universe, because that's what the word means. That's not to say that our cosmic expansion is all that there is, but that whatever there is, it's part of the one single universe, which literally means 'that which is'.

I also have real problems accepting most of the things described under the rubric of 'multiverse' hypotheses (I won't dignify it with the word 'theory'), and especially those which have such features as the 'trousers of time'* in which each decision spawns a new 'universe', and such idiocy as Everett's 'many worlds' interpretation of quantum mechanics, along with the idea that there are a huge number of universes, each running with different physical constants. All of these ideas should get no further than Occam's Razor until such crap is supported by evidence.

In reality, there is no good reason to suppose that the physical constants we experience could actually have different values. Exploring such concepts can be useful in the sense that 'what if' thought experiments can tell us a good deal more about our universe than simply talking about what is. A good example of this is the behaviour of water. If we just look at water, we don't learn as much by simply observing that it always finds its own level as we do if we ask the question 'what would happen if we could heap it u, like a spoon of sugar'. Asking such questions forces us to look at phenomena in a different light, and raises questions that merely observing the phenomenon of energetic equilibrium would never raise, which is why we end up with terms like 'energetic equilibrium'.

Now, there are a few models for cosmic instantiation on the table that allow for multiple instantiation events, such as Guth's inflationary model, with bubble 'universes', and the Turok/Steinhardt 'brane-worlds' model, that give a plausible mechanism for instantiation under which more than one cosmic expansion is more parsimonious than only one. this would seem to violate Occam's Razor on the face of it, and many people actually think it does, but this arises from a misunderstanding of precisely what Occam's Razor deals with. Since we have evidence for the instantiation of at least one cosmic expansion, something would be required to act as a barrier to it happening again. It is this barrier that is a violation of Occam's Razor, because it constitutes a new kind of entity, and therefore an unnecessary multiplication of entities.

*© Terry Pratchett

[DropLogic]

Yeah...what he said.

[Thumpalumpacus]

... and such idiocy as ... the idea that there are a huge number of universes, each running with different physical constants.

I'm unclear why this should be considered idiocy.  Without putting yourself out too much, might you explain why?

[hackenslash]

Without putting myself out too much, parsimony.  

I'll explain in more detail when I've had more sleep and less to drink.

[Thumpalumpacus]

I understand parsimony.  I just don't see how it rules it out ... but then, I'm not the physicist here.  

[DropLogic]

I understand parsimony.  I just don't see how it rules it out ... but then, I'm not the physicist here.  

As a lay person here...I'm gonna go out on a limb and guess that the concept of the multi-verse is idiocy because it's identical to the concept of god.  Something we cannot see, nor have any proof of, yet is considered theory.  Well, god is a fact to his followers, but the point remains.

[hackenslash]

I understand parsimony.  I just don't see how it rules it out ...

Parsimony doesn't rule anything out, but it does provide a good means of determining which hypotheses are worth exploring and which should probably be left alone pending substantive evidence. In this case, since the constants we experience in our cosmos are constant, parsimony dictates that we should probably consider them constant everywhere. Those values are almost certainly what they are for very specific reasons (such as that they can't be anything else, for example) so, in the absence of a good reason to think that they could be different, it is more economical to work on the basis that they can only be what they are.

but then, I'm not the physicist here.  

Neither am I.

[Thumpalumpacus]

There are indications that at least one constant may not be so:

http://www.physorg.com/news202921592.html

DL:  I don't see how the two concepts are identical.

[DropLogic]

There are indications that at least one constant may not be so:

http://www.physorg.com/news202921592.html

DL:  I don't see how the two concepts are identical.

They are more similar than not.

[Thumpalumpacus]

Yeah, I'm still unclear.  Feel free to explicate if you so desire.

[DropLogic]

Yeah, I'm still unclear.  Feel free to explicate if you so desire.

http://www.abovetopsecret.com/forum/thread411715/pg1
In other words: "We don't know what this is. So it MUST be another universe"

To me it sounds the same as: "We don't know why <insert phenomena> happens.  So it MUST be god."

just my op tho.

[Thumpalumpacus]

Then you're ascribing to me a view I don't hold, insofar as I would say "may" rather than "must".