Other People’s Stuff

It’s always a little worrying when this happens, but sometimes I find myself very much agreeing with at least parts of what Lubos Motl has to say. For example see this recent posting to sci.physics.strings. In it Motl argues that

“I think it is premature to try to construct this major framework that would explain the character of vacuum selection and very early cosmology in string theory”


“So my belief is that we will have to understand the nonperturbative structure of the stringy arena using some new universal definition of string theory – a definition that is both non-perturbative (reaches the strongly coupled regions) as well as background-universal (reaches the geometries and non-geometries that are different from the starting one), and only afterwards, we will be able to start answering the stringy cosmological questions in a better context. Without this new tool, everything is just vague guesswork.

In my opinion, the research of string cosmology; stringy inflation; de Sitter space in string theory; scattering in backgrounds with non-standard causal diagrams; and all similar things that have essentially be started by the observation of accelerating Universe back in 1998 – has led to a very small number of intriguing results. There is almost nothing non-trivial and mathematically intriguing going on here; there is as much output as much input we insert. It remains a combination of phenomenology and speculations where conjectures can rarely be clearly ruled out.”

I’ve never really understood why there are fields of “string phenomenology” and “string cosmology” when the theory is still in a state that it can’t reliably calculate anything. While I think it is wishful thinking to believe that if you understood string theory better it would reproduce the real world, at least Motl’s is a consistent scientific position.

Motl is also a fierce opponent of the “anthropic” arguments that have become popular among string theorists. For the latest example of anthropic argumentation, see this posting at Jacques Distler’s weblog.

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10 Responses to Other People’s Stuff

  1. Thomas Larsson says:

    How depressing!

    I found my info on the web a couple of months ago, but was evidently outdated.

  2. Peter says:

    Hi Thomas,

    I was going by a famous graph I’ve seen in many places, e.g. here, which I read as saying that discovery of a 115 Gev Higgs requires

    1. Almost 2 fb^-1 for 95% confidence level

    2. About 5 fb^-1 for 3 sigma

    3. Nearly 20 fb^-1 for 5 sigma

    The most optimistic Tevatron Run II projections now seem to be that 2 fb^-1 would be available by 2006, 5 fb^-1 by the time the LHC turns on (late 2007), and it’s unlikely they’ll ever get 20 fb^-1 since they’re not likely to run the machine for too many years after the LHC is up and running.

  3. Thomas Larsson says:


    I think you are overly pessimistic. I have also seen that 2fb^-1 is required for a 5-sigma discovery of the Higgs (whether combined or for each individual experiment is unclear to me), but surely you can get hints with less than that. People have been excited about 2.5 sigma signals before. It also takes a lot less statistics to rule out a light Higgs; a 5-sigma discovery will take until 2009, but it will be possible to rule out a light Higgs at 95% CL already in 2006. Now that is only two years away, which suggests to me that if the LEP signal is real, some kind of bump should be visible at 115 GeV very soon, if not already.

  4. Simplex says:

    “So my belief is that we will have to understand the nonperturbative structure of the stringy arena using some new universal definition of string theory – a definition that is both non-perturbative (reaches the strongly coupled regions) as well as background-universal (reaches the geometries and non-geometries that are different from the starting one), and only afterwards,…”

    Background-universality reads for practical purposes like a euphemism for background independence! Holy Smolin, Lubos, could this be a nod in the Loop Gravity direction?

  5. Thomas,

    That one got a lot less of press coverage. It was hinted, preliminary, in hep-ex/0105057 and then dismissed progressively via statistical methods. See also plots in hep-ex/9909044 and hep-ex/0009010. The statistic dismissal was based, it seems, on adding other dissintegration channels where signal was not seen. Pretty much the same history than 115 Gev.

    Probably a motivation to forget about this event is that a low Higgs+ it is not compatible with the minimal supersymmetric standard model. I had also forgotten it, until recently a model forced my neurons to expel these papers from my deep repressed memories 🙂

  6. Peter says:

    Grants generally aren’t given on a year-to-year basis, more typically people are part of a group that has a grant that may have to be renewed every five years. So, if you have a permanent job, you don’t need to worry about this each and every year, but every few years you very much need to worry about whether you’ve been publishing enough articles.

    Postdocs and junior faculty are under a lot more pressure. Their jobs may be as short as one-year appointments, and they definitely need to be producing as many publications as possible as quickly as possible if they want to continue to eat.

    There certainly are a lot of very routine, resume-padding articles appearing, but this is not specific to string theory or high-energy theory. Pretty much every academic field, even very healthy ones, have this phenomenon. What’s scary about particle theory in recent years is not how many routine papers there are, but how few there are with any sort of interesting new idea at all.

  7. Peter says:

    With only 200 pb^-1 in Run II, the Tevatron can’t see much that they couldn’t see in Run I, where they had around 100 pb^-1. To start pushing up the mass limit on the Higgs above that from LEP, they need 2000 pb^-1 or so. They hope to get that over the next few years before the LHC gets going.

  8. Thomas Larsson says:

    What is the 68 GeV particle? I evidently missed it.

    Yesterday there was a status report from the Tevatron on the arxiv. CDF and D0 now have an integrated luminosity ~200$ pb**-1 (per experiment), but evidently they don’t see any deviations from the standard model. Does anyone know if this is significant?

  9. No, I am pretty sure that the inertia of stringthings is independent of funding gravy. It is just that when people is trained with a weak mechanism of choosing goals, the herd effects happen (stock market jargon; no pun intended).

    Perhaps experimentalists are more sensible to funding phenomena. I am still astonished about the 115 and 68 GeV particles in LEP2; they were so in hurry to finish the experiment that they did not got time to take more measurements there.

  10. JC says:

    Perhaps from an ulterior motive, it’s a way of folks attempting to justify the government grant funding gravy train to string theory or particle theory in general?

    Regardless of whether string theory is a legitimate or illegitimate field of research, is there any truth to the folklore stories that if you don’t publish anything during a year you’ll end up losing most, if not all, of your grant money for the next year?

    Many papers that show up every day on the arxiv preprint server look like they aren’t much more than the equivalent of “resume padding” for a researcher’s CV. Perhaps it’s not so surprising if it’s papers produced by some 2nd or 3rd rate researchers at some 3rd or 4th rate universities, hoping to get tenure. Or for that matter, postdocs hoping to get an assistant professor job.

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