Multiverses and other kaku-eyed wonders

[Ender W.]

I like to think of our universe a a membrane that exists in a higher dimension. I read a great example in a book my michio kaku, that goes like this. Imagine a 2 dimensional creature living on a sphere. He can wander around all of his life on the sphere, and never find an edge, because a sphere doesn't have an edge in 2 dimensions. but that doesn't mean that there is no limit to their universe. We may be in a similar situation, with other universal membranes floating in a " multiverse" of other universes beyond ours, all with their own isolated laws of physics and mabey even other life forms.

[Martin]

I like to think of our universe a a membrane that exists in a higher dimension. ... with other universal membranes floating in a " multiverse" of other universes beyond ours, all with their own isolated laws of physics and mayby even other life forms.

 

Ender, I think you speak for for many (if not all) of us. At one time or another many of us must have fantasized about alternative universes floating around in a dreamland of higher dimension. Certainly I have.

 

Cosmology is a precision mathematical science based on observation. There are now millions of data points. The job of working cosmologists is to construct math models that fit the data. And then test the models using more data.

 

In this Astro/Cosmo forum part of our function is educational---finding out about mainstream cosmology---so for practical reasons we have to compartmentalize. Extreme dreaming is not part of what we do, as a rule.

 

So some threads get moved to speculations forum.

 

One way of deciding is testability, as professional societies like the GRG see it. The GRG is the main international experts group for general relativity and gravitation. 500-1000 active members. If they think you have an idea that is in principle testable by empirical means, maybe now with present technology or in the next few years, then it's science and you may get invited to give a talk about it at the next GRG conference.

 

The idea has to have a mathematical formulation (so it can be checked numerically against data) and it has to be testable----has to make predictions checkable by future observation. Otherwise it's not established or professional grade science, it is speculation.

 

Speculation can have value as a stimulus, and can have commercial entertainment value in the market place. We shouldn't knock it.

======================

 

So anyway what it boils down to is, can you show us how some of these multiverse ideas are testable? Or better, let's throw it open and ask anybody to explain how any particular multiverse idea is testable.

 

Just kidding about "kaku-eyed wonders" . Let's keep it to multiverses.

[Ender W.]

Well, m theory is what predicts the multiverse, and that is testable with the LHC. So, if the LHC can prove m theory, why cant it prove multiverse?

[Martin]

Well, m theory is what predicts the multiverse, and that is testable with the LHC. So, if the LHC can prove m theory, why cant it prove multiverse?

Ender, unfortunately nothing you say in your post here makes sense, for several reasons.

 

1.M theory does not exist*.

2.Nobody has put forward a prediction of something to look for at LHC which if not seen would rule M theory out----LHC is not expected test M theory

3.No version of string/M theory actually predicts the physical existence of a multiverse.

 

*Or as David Gross says "We don't know what M theory is." He should know, currently the most prominent senior string theorist (since Witten changed fields.) The point is that M theory has been conjectured to exist but has never been formulated. There are no equations, no principles, no models. David Gross typically gives the keynote or summary talk at the major string conferences every year and has repeatedly emphasized this.

If you doubt point #1 then go and find a formulation of M-theory.

 

About point #3, at the main String conference of 2008, "Strings '08" held at CERN in August the string leadership did not ask the multiverse people in to give even one multiverse talk. That is, among the people actually doing string/M research, multiverse ideas smell so bad that they basically invite talks about 30 other topics everything else but. I see that Kaku was not invited to talk, but AFAIK he was not an invited speaker at Strings even when multiverse was fashionable in 2004-2007.

 

In other words the accepted authorities about string research are very far from admitting that any corner, any version of what they are working on predicts the physical existence of a multiverse. The multiverse talk---popular in the media---seems to be something of an embarrassment. Kaku's papers are not much cited, not of late anyway. His importance has been exaggerated in the media and whatever he says or is involved with is not likely to matter much.

 

I would say 2005 was probably the height of stringy Multiverse popularity among real string theorists. Multiverse was talked about a lot at Strings '05 (it was in Toronto that year). However it was voted down 3-to-1 by some 400 string theorists at an informal show-of-hands poll conducted by Steve Shenker after a panel discussion. It has problems. It could make a comeback some day--as I say fashions change, the pendulum swings. But for now at least, an actual stringy multiverse is not predicted (outside of the attention-grabbing fringe).

 

Some types of inflation scenario involve the physical existence of a multiverse. However no inflation scenario has been tested. They all involve some imagined inflaton field which is just postulated to make the scenario work. So far inflation lends no scientific support to multiverse because there are just as good inflation scenarios which do not produce multiverse---no rational empirical reason to prefer the scenarios that do over those that do not.

Edited January 11, 2009 by Martin

[Ender W.]

OKay, fine. GIVE ME A BREAK THOUGH, YOUR SINGLING ME OUT BECAUSE I RESPONDED TO A POST. Seriously, he asked how big space was, i gave him the answer i believe to be true. Im 15 for gods sake, i've not even set foot on a college yet, so just ignore me if u don't agree with me

[Cap'n Refsmmat]

This is a discussion forum. Please don't be angry if people respond to your post or make corrections -- that's the way it's supposed to be. Everyone learns this way.

[Ender W.]

Im not angry, but i feel singled out, which i feel was unessacary. He created an entire new post with a quote of mine, i didn't start this conversation, he did. It was unessacary and rude to single me out like that.

[Martin]

Im not angry, but i feel singled out, which i feel was unessacary. He created an entire new post with a quote of mine, i didn't start this conversation, he did. It was unessacary and rude to single me out like that.

 

Ender you are complaining about something that is policy and routinely done.

Look back at post #425 by Phi for All in the previous thread

http://www.scienceforums.net/forum/showpost.php?p=458207&postcount=425

 

Warning: This is a large thread on current mainstream cosmological concepts. Any speculative additions will be moved to the proper section. If you are posting to this thread rather than starting a new one in Speculations, please keep to the original intent.

 

Soon after that general warning from a moderator, you posted something that was both highly speculative and off-topic as we are trying to define the topic of that thread, namely "current mainstream cosmology".

 

You were not singled out. I simply carried through on Phi's announcement. The same would apply to other speculative off-topic posts.

 

You may not realize that Kaku is not mainstream cosmology. His papers are not cited in the current cosmology literature, and he is not invited to speak at the main cosmology conferences. I suppose he may be widely regarded as a self-promoting lightweight or pseudoscientist. No disrespect intended to Kaku, but his stuff is just not relevant to contemporary mainstream cosmology, or valuable in a science sense. He is a media figure. So perhaps you didn't understand this. But when you begin a post by "I like to think of our universe as....." that is clearly speculation. Right? Have to go, back later.

Edited January 11, 2009 by Martin

[Cap'n Refsmmat]

We do not ever intend to single someone out or be rude. We just try to help everyone learn through discussion.

 

But whatever. Let's move on.

[Martin]

We do not ever intend to single someone out or be rude. We just try to help everyone learn through discussion.

 

But whatever. Let's move on.

 

I agree entirely!

 

The topics here are speculative multiverse-related, and there are no links to professional research papers, so it does not actually belong in the Astro/Cosmo forum. I reckon it can be continued more properly in Speculations and will move it now.

[NowThatWeKnow]

OKay, fine. GIVE ME A BREAK THOUGH, YOUR SINGLING ME OUT BECAUSE I RESPONDED TO A POST. Seriously, he asked how big space was, i gave him the answer i believe to be true. Im 15 for gods sake, i've not even set foot on a college yet, so just ignore me if u don't agree with me

 

15? You are doing well for your age. I am happy to see young people interested in science.

 

From your perspective it may seem like Martin is singling you out but I do not think that is the case. He is a moderator and is just enforcing the rules. If you re-read his first reply to you in this thread, he took a very gentle approach to calling you on speculation. I recently came from a forum that was not moderated so speculation and other things turned order to chaos. There is a place and time for speculation and there is a area for it in these forums. Questioning paradoxical theories and observations that seem to contradict physical laws lead to some speculation that seems to be allowed.

 

Now, lets have some fun.