Is There Intelligent Life On hep-th?

There are yet more hep-th articles on the anthropic principle this week, following recent ones devoted to the implications for fundamental physics of the heights of giraffes and sizes of brontosaurus brains. The TASI summer school designed to train particle theory graduate students this year featured talks by Raphael Bousso expounding the anthropic landscape pseudo-science as a “solution” to the CC problem. His lecture notes are now available. In them he does refer to one problem that plagues this subject, that of how to identify the intelligent observers whose probability of existence everything depends on:

The problem of characterizing observers, especially in vacua very different from ours, remains challenging.

Last night a new paper on this subject appeared on the arXiv, by Maor, Krauss and Starkman, making the point about anthropic arguments that:

arguments of these sort (see for example [3] [reference is to papers by Bousso]) strongly rely on the assertion that we must be typical observers, an assertion without sound fundamental scientific basis at the current time.

The authors end with a conclusion about what you can learn from anthropic arguments:

Finally, the correlations illuminated by anthropic reasoning imply that what we ultimately learn from anthropic arguments is that the existence of us and the existence of the observed value of Lambda do not contradict each other. That is nice, but hardly surprising.

In their acknowledgment section they thank Bousso for “lively discussions”. He thanks lots of people in his acknowledgments section, but not them. I don’t know about this question of intelligent life in other pocket universes, but the question of whether there’s intelligent life on hep-th these days seems to still be open.

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17 Responses to Is There Intelligent Life On hep-th?

  1. Alfonso Martinez says:

    Even shorter, “correlation is not causation”.

    If only David Hume could witness what sort of science we do nowadays! Not to speak of the use we give to the money provided by our funding agencies, of course.

  2. locrian says:

    Thanks for the quotes from the Maor paper. That last one was perfect.

    It’s a shame they need quoting, though.

  3. SnarkFest says:

    When people who have demonstrated an attitude towards philosophical reflection ranging from dismissiveness to outright contempt have philosophical ideas of their own (whether or not they acknowledge them as such) the results can generally expected to be crap.

    This is just another case in point.

    (Of course this is not to say that crappy ideas, and execrable formulations of ideas, can’t originate with professional as well as amateur philosophers.)

  4. Greg Egan says:

    Another good paper on this topic is “Are We Typical?” by Hartle and Srednicki:

    Bayesian probability theory is used to analyze the oft-made assumption that humans are typical observers in the universe. Some theoretical calculations make the selection fallacy that we are randomly chosen from a class of objects by some physical process, despite the absence of any evidence for such a process, or any observational evidence favoring our typicality. It is possible to favor theories in which we are typical by appropriately choosing their prior probabilities, but such assumptions should be made explicit to avoid confusion.

  5. Jim Clarage (astonished biophysicist) says:

    I admit the quick skim of Bousso’s lecture notes got my attention (section 7) where he reports that his developments have

    changed the status of string theory: the theory has made contact with experiment

    But as I read more carefully I am shocked that reasoning such as,

    Moreover, it is reasonable to suppose that regions without galaxies do not contain any observers.

    survives unchecked in any university who’s lectures (they are lecture notes afterall) are attended by other disciplines, e.g., biologists, psychologists, cognitive scientists. As I’ve posted here before, even most modern theologians would blush at such anthropocentric reasoning. It genuinely goes beyond anything Ptlolemy or any other pre-Copernican cosmologists might have guilty of about Man’s central place in the universe and its laws.

  6. Ori says:

    So why wouldnt you send some intelligent paper instead of writing content-less postings on the blogosphere ?

    If you are so smart you must have some good ideas (with equations and not just words)

  7. chris says:

    because he is woit the destroyer, not woit the constructor.

    oh, you still need formulas these days to go on hep-th :-)? a yes, the giraffe’s height is related to plancks constant by more than words i forgot.

    i wonder, if one could formulate a meta-antropic principle:
    given any kind of universe, if an inteligent observer evolves (s)he will always develop a theory of why the universe has to be such as to support this particular form of intelligent observer.

  8. dragon says:

    What I also find startling about Bousso’s lecture notes is the style, the way he heaps scorn on people who are stupid enough to disagree with him. I’m told that this is indeed his personal manner, but to see it coming out in ”lecture notes” is a bit of an unpleasant surprise.

  9. D R Lunsford says:

    You know, there is a symmetry that may have been overlooked – the giraffe can face any direction and still maintain his height. So there should be a gauge theory of giraffe perambulation. No lion’!


  10. Shantanu says:

    Peter, forget about all this. Did you find anything interesting from
    the Lepton-photon symposium(slides now online). also what do you think
    about the “Beyond Einstein” decision, now that it is out.

  11. Peter Woit says:


    As far as I can tell, there was nothing really exciting announced at lepton-photon, just lots of solid progress. Rumors of hints of a Higgs didn’t pan out…

    As for “Beyond Einstein”, I just don’t know enough to have an informed opinion.

  12. Jack says:

    Nowadays these physicists have gone to a different field (philosophy). Physics concerns, in fact, what is measurable.

    It is also clear that this kind of philosophy has no more scientific foundations that the hypothesis that there is a God, who has built the Universe and all that exists.

  13. oxo says:

    If these guys are correct, then LQG has been measured..

  14. gravitonto says:

    I think naive dimensional analysis and order-of-magnitude guesstimates are not the most solid possible basis for such a revolutionary claim as the authors make. But, what the heck, J. Ellis is the second most cited author in HEP, so I guess it must be true: quantum gravity has finally been experimentally discovered. hoooo-rrrraaaaayyyy!!!

  15. woit says:

    oxo and gravitonto,

    You folks are in the wrong posting, this was discussed a while back, see

  16. gravitonto says:

    Sorry about that. I guess I should have known that preprint couldn’t possibly have gone unnoticed and undiscussed here…

  17. Pingback: Not Even Wrong » Blog Archive » An Exceptionally Simple Theory of Everything?

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