Quick question: Is the multiverse theorized to have an origin?

[The thinker]

Hi,

I am just curious as to whether the "multiverse" predicted by M-theory (and other similar theories) is theorized to have an origin.

Or is it envisaged as some sort of infinite membrane on which our universe and others like it are created but itself having no origin, cause or point of creation?

Thanks

 

[marcus]

Hi,

I am just curious as to whether the "multiverse" predicted by M-theory (and other similar theories) is theorized to have an origin.

So far M-theory has not been formulated, so it does not predict anything.

However, one could ask a question like yours: if M-theory were formulated (not merely imagined but written down in some definite set of principles and equations) would it require the physical existence of a multiverse?

I think the answer to that is no.

There is, as far as I know, no version of superstring theory that requires a multiverse to actually exist.

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

Multiverse scenarios proliferated during the period 2003-2007. Interest in these scenarios, and the related string Landscape (of possible different versions of physics) seems to be on the decline. If you want a quick update on changing fashions, have a look at this:
http://www.math.columbia.edu/~woit/wordpress/?p=1285
A symposium on the String Landscape was just held last week at Princeton. The speakers were top people, it's worth reading what they had to say.

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

As far as your question about a multiverse point of origin, the answer is again no. Typical multiverse scenarios have no beginning.

An important book will appear in the first half of 2009 called Beyond the Big Bang, Prospects for an Eternal Universe.

This will feature chapters by a wide range of experts---top leaders in all the leading types of multiverse speculation.

If you are interested in multiverse thinking, I would advise you to make sure your local public library gets this book. The articles are written to be accessible to a wider audience---not overly much math---plenty of basic explanation. Here are two links

https://www.amazon.com/dp/3540714227/?tag=pfamazon01-20

http://www.springer.com/astronomy/general+relativity/book/978-3-540-71422-4?detailsPage=toc

The second link gives the book's table of contents. The predicted publication date is 4 May 2009.

 

[The thinker]

So far M-theory has not been formulated, so it does not predict anything.

However, one could ask a question like yours: if M-theory were formulated (not merely imagined but written down in some definite set of principles and equations) would it require the physical existence of a multiverse?

I think the answer to that is no.

There is, as far as I know, no version of superstring theory that requires a multiverse to actually exist.

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

Multiverse scenarios proliferated during the period 2003-2007. Interest in these scenarios, and the related string Landscape (of possible different versions of physics) seems to be on the decline. If you want a current overview, have a look at this:

Oh wow, I thought that they were an integral part of most string theories, I also had no idea that M-theory was not even, well, a theory!

Thanks!

 

[marcus]

Oh wow, I thought that they were an integral part of most string theories, I also had no idea that M-theory was not even, well, a theory!
...

There is ample speculation as to what M-theory might look like, but it is easier to talk about various individual superstring theories that are more explicitly developed. If you are interested in them, there are plenty of people here at PF to discuss them with.

On the other hand if you are interested in multiverse scenarios, that is somewhat of a different topic. Superstring theories do not predict the physical existence of a multiverse.

The widespread impression that ST requires a physical multi came in the wake of a paper published in 2003 by a Stanford group referred to as KKLT (Kachru, Kallosh, Linde, Trivedi). The KKLT paper showed that under fairly general assumptions ST allows for some
10⁵⁰⁰ different versions of physics.

That is, ST is not as helpful, as had earlier been hoped, at explaining why we have exactly the physics which we do have.

This number has now been increased to 10^100,000---an even bigger landscape of possibilities.

The KKLT paper caused some people to turn away from ST and search for other theories which might have more explanatory and predictive power.

Some of those who did not turn away to look elsewhere began to speculate that it would ultimately prove impossible to explain the particular form of the laws of physics, and the key fundamental constants. We may as well give up, they speculated, and accept the rules of physics as accidental parts of our environment. Just like the fact that our solar system has two giant planets, two medium size, and a handful of smaller. The vision of a multiverse can serve as both a comfort and an excuse to someone who is inclined to abandon the traditional goal of mathematical science. Susskind has been a vocal proponent of this posture of acceptance.

One can say that via the Landscape problem, string has an affinity for multi. But it does not actually predict the physical existence of a multiverse. This affinity was mistaken in the popular media for a prediction.

Things are changing though! Every year there is a big international Strings conference which gives a window on how things are going--and in past years (2003-2007) there were a bunch of Landscape and multiverse talks. This year however, the Strings 2008 organizers did not invite any speakers to talk about multiverse stuff.
Susskind didn't talk. Michael Douglas didn't. Linde didn't. Kallosh gave a talk but it was about something else. Huge shift. Because just a couple of years ago the Landscapers seemed to be gaining overwhelming strength.

We'll be watching how the programme for Strings 2009 shapes up.

Meanwhile, check out Woit's report of that Princeton symposium I gave a link to.
http://www.math.columbia.edu/~woit/wordpress/?p=1285

 

[Fra]

I am just curious as to whether the "multiverse" predicted by M-theory (and other similar theories) is theorized to have an origin.

Or is it envisaged as some sort of infinite membrane on which our universe and others like it are created but itself having no origin, cause or point of creation?

Even though it's a matter of definition, the whole "multiverse" notion has never made sense to me.

But with a modest stretch of imagination, I can see this (generally, not speaking on M or string theory specifically) as dual to the idea of multiple observers. Add to that the idea that even physical law, are to be subject of the same constraints as other "observables". This should force the concept of physical law, into the ideal of measurement theory.

Then one might have a picture that different observers in principle can "see" different laws. And thus depending on how you defined universe, they live in different universes. But I think that's confusing.

What might make sense to though, is the multi-observer idea. In this picture, the question of the origin of the universe becomes dual to the question of the origin of observers.

So a universe with given law, are the same as a population of coherently evolve observers that "sees" the same law.

One can for example ask what the consequences are when two observers get contact, that "sees" different law? Surely, some interaction will take place, but what?

Such a multiple-observer view, is to me the only reasonably sound implementation of a multiverse idea. The two views are opposite.

/Fredrik

 

[Fra]

One can for example ask what the consequences are when two observers get contact, that "sees" different law? Surely, some interaction will take place, but what?

Once you start thinking like this, which I've done for a while, the logical step is to consider the notion of equilibrium at the level of physical law. Consistency requires that if the two observers, exit the interaction in a new, (but stable) configuration, they will have negotioated a new common view of law. Thus, one can imagine the nice picture that the result of observer-observer interaction is simply a kind of negotiation of mutually observed law, and the evolution of law might manifest itself as the evolution of the mictrostructure of the observers. This can be further elaborated, a mictrostructure can simply be changed, but it can also shrink and loose complexity! Or it can also grow in complexity. It's not hard to see the unified vision in here.

/Fredrik