# Multiversal Journeys

One of the many efforts to promote the Multiverse to the public way back when (2005-2007, some of their advertisements are here) was an organization called Multiversal Journeys. Back in 2006 they got $77,000 in funding from the Templeton Foundation (via FQXi). Since 2007 they seemed to have disappeared, with no more scheduled public events as far as I could tell. Now they’re back though, with an upcoming event defensively called Clarifying theoretical physics and cosmology misconceptions for SF Bay Area journalists. It’s unclear exactly what they think the misconceptions are that such journalists need to have clarified. One of the three announced speakers (John Terning) might actually be able to do some clarification, but the other two seem more devoted to the spreading of misconceptions. Yasunori Nomura likes to promote the idea that the landscape and the many-worlds interpretation of quantum mechanics are one and the same thing (see here and here), a claim I believe few serious physicists have ever been able to make sense of. He also claims that the multiverse can be used to make predictions about physics, and back in 2009 used the multiverse to predict that the Higgs mass would be 141 +/- 2 GeV (see here). This prediction played a central role in the film Particle Fever, which featured David Kaplan and Nima Arkani-Hamed during the period leading up to the Higgs discovery explaining how a 140 GeV Higgs would mean the multiverse was right. Will Nomura clarify for the journalists any misconceptions they might have about what scientists are supposed to do when their theory’s well-publicized prediction is tested and shown to be wrong? The other speaker is Texas Tech chemist William Poirier, who has some sort of “Many Interacting Worlds” theory, which supposedly shows that the observed behavior of particles indicates the existence of parallel universes (see here). Again, I’m curious what misconceptions about physics he plans to clarify to journalists. Update: I see that this event will be funded by at$5750 grant from FQXi to Multiversal Journeys (Fall 2014 Mini-grant).

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### 23 Responses to Multiversal Journeys

1. Filux says:

Ah, so the multiverse does make predictions and the prediction was wrong. So, the multiverse is falsifiable. Therefore, you were wrong, Peter.

2. KJ says:

Filux,
You misunderstand the nature of the multiverse theory. All Nomura’s failed “prediction” means is that the particular flavor of multiverse theory he was espousing in 2009 is false. It does not mean that multiverse theory itself is false. In some other version of multiverse theory, the Higgs mass takes precisely the value that was found at the LHC. In fact, since he is still promoting multiverse theory, he clearly still believes in it despite his failed prediction. And that is precisely Peter’s point: Every possible outcome can be “predicted” by some flavor of multiverse theory, thus it is not falsifiable.

3. Martin Kochanski says:

I have been meaning to ask for some time whether your observations of multiverse mania have got you anywhere near an answer to the question “What is the multiverse for?”. To offer meaningful criticism of any project it is first necessary to know what the project is trying to do. In this case the doers of the project often don’t seem to know, or even to want to know, so it seems to be up to you.

I dont’t even find it easy to discern whether the multiverse is meant to encompass universes with all possible values for the constants of nature, or only of some of them. Or, for that matter, whether we are talking about one common set of laws of nature into which the constants are plugged (raising the question “Why?” all over again but about laws this time rather than constants), or whether there are universes for every possible set of laws as well.

Does the multiverse contain a Newtonian universe? If not, why not?

4. Peter Woit says:

All,
Just deleted a long thread of arguments about math/physics/AdS/CFT, which really had nothing to do with this.

Martin,
The goal is to justify failure. The multiverse did it, so the fact that string theory/susy/your favorite theory hasn’t worked out despite 40 years of effort is not the fault of your favorite theory and you can keep on working on it, despite the failure of the idea.

5. Patrick Dennis says:

Peter, have you done a column elaborating your own take on many -worlds?

6. Peter Woit says:

Patrick Dennis,
I’ve probably commented on this somewhere, should someday write more. I don’t want to start a discussion here (it’s a complex topic). In brief though, my point of view is that you can consistently talk about decohered states as different “worlds” in some contexts if you feel like it, but these are just empty words, and the people using them often do so to evade the interesting questions about QM (how does classical behavior emerge? Why certain observables? why the Born rule? etc.).

Adding this empty “interpretation” to an empty claim of a multiverse with different laws of physics in each universe seems to me to be emptiness^2, and as far as I can tell that’s what Nomura is trying to sell.

7. Cormac says:

Hi Peter, I have a different answer to the question “what is the multiverse for?”.
Excuse the armchair philosophy, but my understanding is that the hypothesis of a multiverse was not originally proposed “for ” anything, i.e., was not proposed as an answer to any particular puzzle. Instead, it emerged uninvited as an unattractive consequence of most models of inflation. While the hypothesis of inflation gives predictions that are nicely consistent with observation, the downside is that it has proved impossible (so far) to rule out the prospect of inflation happening at different rates in different regions of the infant universe…so the multiverse is what you might call a ‘bastard’ theory.
The fact that some have jumped on the idea to fit various other proposals should not cause us to lose sight of how the idea initially arose..

8. vmarko says:

Cormac,

As far as I could tell, what came from inflation was the most benign form of the multiverse — a bunch of bubbles in the ever-expanding spacetime, all of which have identical coupling constants. Such a thing doesn’t even really deserve the name “multiverse”, as it is a single spacetime continuum with a single set of laws of physics (and with a somewhat complicated structure), i.e. a “universe”.

The first real problem started when string theory got mixed with this scenario, with its 10^500 vacuua, so that low-energy physics could in principle be different (and random) for each bubble. Although this is arguably also still just a single spacetime continuum, one could justify the name “multiverse” in some way.

The second real problem started when people started making identifications of different bubbles with different wavefunction branches in the many-worlds interpretation of QM. This is where things really got messy and the “multiverse” idea got promoted to cargo-cult levels… 🙂

9. Paul Benoit says:

By the strength of your conviction, I assume you have a solid rebuttal to the Many Interacting Worlds approach? Seems to me that if he can get the same precise predictions with a vast degree less ‘work’ then he’s on to something. You appear to be opposed to his view but have proven yet to provide anything at odds. I don’t want to believe in any form of parallel universe, it’s messy, unknowable, and puts an insurmountable barrier far to close in the future for comfort.

I’m disappointed in your lack of informed reposte to any of it thus far.

10. Peter Woit says:

Paul Benoit,

Look, there are literally thousands of people out there who are convinced that they have some revolutionary new way of replacing the fundamental ideas of quantum mechanics by something they find more appealing. If one paid close attention to even a small fraction of these (such as the ones who get a press release issued and get in the media) and tried to carefully explain what was misguided about what they are claiming, that would be a full-time job. I’ve got better ways to spend my time, already waste far too much of it trying to argue against bad ideas being pushed by very prominent theorists, so don’t feel the need to branch out into arguing against bad ideas that virtually no one takes seriously.

In this case I see no evidence at all that getting rid of wave-functions and the Schrodinger equation in favor of “Many Interacting Worlds” is any sort of improvement of the conventional theory. The claims about “same predictions with less work” are about certain specific approximations to very complex quantum systems and maybe are useful there. As far as I can tell, this idea makes simple quantum systems far more complicated and hard to analyze, so at a fundamental level, it’s an idea for “(maybe) same predictions with a lot more work”.

11. Neil says:

It is not any of the multiple multiverses that I object to. It is the idea that coupled with the anthropic principle, the multiverse has explanatory power.

12. marten says:

It should make no difference whether the multiverse concept is coupled with the anthropic principle or with the dinosauric principle.

13. Andrew Thomas says:

The MWI doesn’t attempt to “get rid of wave-functions and the Shrodinger equation” – it is merely an interpretation. Which means it takes the results you already have, and the equations you already have, and then says “Oh, this appears to indicate the existence of an infinity of parallel universes”. But, apart from that it brings nothing new, or changes any of the equations you already have, or else it would be testable.

14. Andrew Thomas says:

Paul Benoit says: “Seems to me that if he can get the same precise predictions with a vast degree less ‘work’ then he’s on to something.”

Yeah, it would be, but he can’t.

15. Andrew Thomas says:

Can I point out that absolutely ANY interpretation of quantum mechanics you might want to dream up – no matter how insanely crazy – would be 100% equally valid as the MWI (as long as it fitted the results). Which is why we have so many interpretations of quantum mechanics – all on exactly the same level of validity.

16. Nobody says:

The beloved many worlds interpretation is supposed to be simpler because “infinity is simpler than 1” (no symmetry breaking). But is it? Which transfinite cardinal number are we talking about? If the 1st, why is that simpler than 1? Anyone with an IQ over 80 can learn to count starting with ‘1’. Can you teach him to understand transfinite cardinals?

If we have a continuous distribution of probability, the countable infinity will not do anyway. How does the continuum hypothesis fit into this “infinity is simpler than 1” justification for calling many-worlds simple.

17. Magnema says:

@Nobody: Saying “all” is far easier than saying “choose this one” – and I’m pretty sure that holds up from an information-theoretic standpoint, although I don’t know too much about that myself. It’s not the “1” that’s the problem; it’s the “that one” that is the problem.

Of course, it’s not quite “all” (unless we’re talking Lewis’ modal realism), it’s “all with XYZ properties,” but it still stands that “all with XYZ properties” is simpler than “this one with XYZ properties”…

@Peter Woit: So your problem with MWI (setting aside the many people who pretend to understand quantum mechanics but don’t) is not so much that it’s a bad theory, or even that it shouldn’t be preferred fundamentally, but rather that it’ll end up being a lot more work for (at best) the same results? So, seeing as we should use collapse mechanics for all practical computations anyway, it’s simply not worth studying, so to speak?

18. Andrew Thomas says:

Magnema: ” It’s not the “1” that’s the problem; it’s the “that one” that is the problem.”

Essentially, this is the age-old battle against indeterminism which goes all the way back to Einstein and Bohr: “God does not play dice”. Why should it be “that one?”

I suspect people will always try to fit quantum mechanics into a deterministic, classical framework. But that’s purely through human bias – not through cold analysis of data. The MWI is merely another step in an attempt to remove indeterminism. I’m sure it won’t be the last.

19. Peter Woit says:

Enough about MWI. I think there’s now plenty of evidence for my point of view that discussion of this topic is just a complete waste of time.

At the risk of being trivial and other things, I want to note that sometime in the last week or so Jeopardy had a category/question to which I (on my couch) and the ringing-in contestant answered “multiverse”. He was told he was wrong and the “right answer” was “parallel worlds”. Well..some time later Alex awarded the contestant his lost points saying that the referees judged his answer to have been equally correct. Not sure if this is a good or a bad thing….tho it did amuse me 🙂

21. tt says:

just want to point out ‘MWI’ = many worlds interpretation,
is not exactly the same as ‘MIW’ = many interacting worlds

22. Peter Woit says:

tt,
Thanks, my last comment should have read “MWI or MIW”.

23. Gus Bici says:

Sean Carroll compares Multiverse to Australia: