Why I don't believe in parallel universes

[JuliaL]

I don't think it's a problem of daring to conceive of one thing or another, it's rather a problem of statements becoming meaningless if you throw logic out of the window. For instance, what does existing still mean for something that defies logic?

How can a statement become meaningless while still existing.
It would at least show a certain distribution of letters.
Even non-existent statements have symbolic meaning, though they all say the same thing.

I run rings around you logically!
"Aaarrrrgh, intercourse the penguin!"

[Anomalocaris]

I run rings around you logically!
"Aaarrrrgh, intercourse the penguin!"

I think the ring is the trail of your foot prints made as you chase your tail. A very lovely tail, to be sure, especially when it is associated with the reflexive use of "intercourse" as a verb.

[Mister Agenda]

We may have more reason (or less) to take this idea seriously soon:

http://www.telegraph.co.uk/news/science/...lider.html

And probably not soon, but maybe this:

http://www.pbs.org/wgbh/nova/next/physic...backwards/

[AFTT47]

We may have more reason (or less) to take this idea seriously soon:

http://www.telegraph.co.uk/news/science/...lider.html

From the first link: "It is even possible that gravity from our own universe may ‘leak’ into this parallel universe, scientists at the LHC say."

That one has always intrigued me. I'm but a layman when it comes to theoretical physics but the spilling of gravity into other universes or dimensions seems like such an elegant explanation as to why the gravitational force is so weak.

[Anomalocaris]

"Elegant" in this context means simple, overarching, intuitive, and easily comprehensible explanation made to appear brilliant by a near total absence of evidence of what reality actually is.

[AFTT47]

"Elegant" in this context means simple, overarching, intuitive, and easily comprehensible explanation made to appear brilliant by a near total absence of evidence of what reality actually is.

Granted. It's not remotely a done deal but an intriguing avenue of research.

[Alex K]

That one has always intrigued me. I'm but a layman when it comes to theoretical physics but the spilling of gravity into other universes or dimensions seems like such an elegant explanation as to why the gravitational force is so weak.

Yes, it's a nice idea. And it has fun consequences, like black holes@LHC

The theoretical difficulty that follows next however is to explain why the extra dimensions are large enough to provide this dilution. In the worst case, getting this hierarchy of size of the extra dimension compared to other scales in nature is just as bad as getting gravity so weak in the first place. But that's just a technical concern, in the end we have to run the LHC and check for this kind of energy leakage into gravitons.

But anyhew, extra dimensions, and the usual concept of parallel universes, are kind of two different ideas.

[downbeatplumb]

I am not really up enough on the concept of multiple universes to comment fully but have heard that it could explain why gravity is so weak and seems to be not ruled out by physicists.

[Alex K]

I am not really up enough on the concept of multiple universes to comment fully but have heard that it could explain why gravity is so weak and seems to be not ruled out by physicists.

It can never be completely ruled out if you accept to stretch your expectation how much of the weakness of gravity the model should be able to explain.
These models have already been constrained by the first run of the LHC in how big the extra dimensions can be, but they still remain viable to a certain extent.

There are a bunch of very different ideas floating around which get mixed up. The typical one is this one, that there is the idea that extra dimensions exist in which only gravity can extend, and it therefore gets diluted. The same guy also had the wacky idea that one could have an uncountable numbers of identical parallel kinds of matter occupy the same space without interacting except through gravity, and this would also explain why gravity is weak. I don't know where that went, but the first possibility is taken more seriously. Then there's the unrelated idea that the String Theory has so many different ways the laws of nature could be, that we can end up in one where they are as we observe them for anthropic reasons.