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Featured A No metastable type IIB de Sitter vacua

  1. Aug 8, 2018 #61

    Fra

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    I agree.

    As we know already I think what's lost is more than 15 years, it may unfortunately be the ideas and contribution of a whole generation of physicists.

    I remeber well 20 years ago in Danielssons office how he adviced me against pursuing any future in theoretical physics research unless it was in string theory! and he also didnt seem open to even reflect upon different ideas. So it was clear that either you had to fight research political battles or join the mentality.

    For me the integrity of the intellectual quest was far more important than academic route so the choice was easy.

    /Fredrik
     
  2. Aug 9, 2018 #62

    Ken G

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    This is why it is so important to maintain a clear view of what differentiates science from other things, including mathematics. This thread makes the key point that in mathematical physics, as anywhere in formal mathematics, following non-rigorous ideas too far can lead to false turns and wasted time. Obviously mathematics is important in science. But it does raise the question, what is different about mathematics and science? In mathematics, it is important to know what is proven, what must be true. In science, it is also important to know that one does not prove, one explores. Are we seeing a kind of collision of these mindsets when people think a theory is so beautiful it doesn't need testing, and doesn't need an observation to be obtained that no other theory can explain? That mindset is pretty close to forgetting what differentiates science from just about everything else, because science is the only place where the gold standard is "look for such-and-such, and if this theory is good, you will see it."
     
  3. Aug 9, 2018 #63

    Fra

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    I largely agree.

    But I think one should distinguish between standards in scientific community and the motivation of individual researchers.

    I have absolutely no problem with wether some potential genius follows guidelines and intuition in the search for something that could later be either "proved in math" or "corroboorated in physics". It is actually not surprising that even the most briliant idea, can initially be met by scepsism from the scientific community as there are yet not hard proof and only fuzzy subjective motivations. If these nutcases (or geniuses if you prefer) arent "allowed" then the creativity required for the evolution of science is severely crippled. One essential mechanism of evolution is variation, but the wildness must be "tamed".

    So in this sense, i have no problems with that we "evaluate" the paradigm of string theory, or that some passionate brave theorists commit to exploring its implications. Because who knows if they find something noone expected.

    But I have an objection with how it becomes a self-inforcing mechanism that risk intellectual inbreeding, because the same persons that are supposed to guide students and future physicists. This is where the problem for scientific community and wasting resources comes in.

    But Danielsson himself has said several times (I recall one panel discussion where he argues for a popular audience against Max Tegmark) that if it is found that string theory ends up beeing "only" mathematics he will be dissapointed. So I do not think he thinkhe is doing mathematics, he is doing physics. As far as I understand, his perspective is that string theory in his perspective is the most promising candidate to unify GR and QFT, in despited of all its issues and problems. This is the rational reason why you keep developing it.

    If I agreed with this, i would also be looking at string theory. But my analysis has found too many problems, in the premises of QFT and GR that are carried overy completely to string theory, which i think are the where the problems are hidden. This is why i find string theory to actually in a sense be too conservative (Danielsson has himself used this word, he thinks string theory is a "natural extrapolation" in some way from QFT, that he calls "conservative"). And in a way i agree its conservative in one way(the wrong way), but crazy in other way (also the wrong way).

    And in a way i think it is the most promising, DEVELOPED idea, but the problem is that that is almost like a self-fulfilling prophecy, as you discourage variation.

    /Fredrik
     
  4. Aug 17, 2018 #64

    Urs Schreiber

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    This shall be my last message here, as it seems from this point on you can follow this social event from the mass media.

    The talk
    • Thomas van Riet, "Status of KKLT", talk at Simons summer workshop 2018 (recording)
    is worth watching; not just for the social curiosity after the talk in 1:30-1:40, but since it's a good talk and interesting to see the many questions being raised by the audience, and the replies by the speaker.
     
  5. Aug 29, 2018 #65

    Urs Schreiber

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    Maybe I should keep logging the discussion after all, might be a useful compendium later. But I will be brief.

    Today a whole bunch of articles from KKLT-related groups claiming that they didn't make a mistake after all. But it looks like they don't quite address the issues that have been raised. See Motl's summary here.
     
  6. Aug 29, 2018 #66

    Urs Schreiber

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    Van Riet gives a decent analysis of today's flood of papers (here):

    --BEGIN QUOTE --

    My 2 cents about these papers in case anybody would care. But before so, I must admit I only had a very superficial reading of all of them.

    Paper 1 is interesting and a complementary review to the one I wrote with Danielsson. They seem to cover very similar topics (we did not cover quintessence though). But were we concluded trouble, they conclude the opposite. That is ok and makes this review a good read for folks interested in the topic, but I highly suggest to read my review with Danielsson and the references therein, to have a balanced view. But I do not consider this review as a direct attack on the dS Swampland since no new computations were done that refute existing criticism it seems. Also the issue they point out about double fine-tuning in quintessence was already addressed by Vafa et al when they published their papers.

    Then the paper 2 by Kachru and Trivedi. It is good that their arguments are in print now. But I think it contains what they have been saying already for many years in defense of KKLT. Their EFT reasoning can make sense for sure. But it is not enough and subtleties are around the corner almost everywhere. But like the previous paper, this is good to have and especially this one is useful to pick apart for anyone that cares about criticism on the flux program. But, again, nothing too new.

    Paper 3 by Wrase-Kallosh is really nice for me personally. Contains a very interesting idea. But I doubt it survives a thorough study of the open-string sector as you mention. For instance brane-flux decay here could be perturbative. I will check that. But as an idea paper, it is great! Both these authors are indeed great experts on the supergravity side of the story and they definitely came with a nice suggestion that needs to be studied. Also here, I doubt it counts as any evidence against dS Swampland ideas. But they do not push that either in their paper.

    Paper 4 does not really address the issue from the start. As a 4D supergravity paper there might be something interesting, but it says little about the paper by Moritz et al they want to refute . Why? The latter paper is really about a 10D computation. Moritz et al then tried to reformulate their results in 4D sugra and are so nice to put it into the language of constrained superfields. That language is not guaranteed to make sense always. Anyhow, today's paper notices there is small issue with the constrained superfield description in a different position of moduli space. But I do not think that Moritz et al intented their results to apply that far away in moduli space in the first place (in line with Swampland distance conjectures).

    Paper 5 could indeed fall into the problem you mention. But observational cosmology papers seem very shaky and there have been various tensions among complementary observations. As far as I can tell the current data are still easily fitted with time-dependent dark energy.

    The possible existence of a dS landscape has huge implications. So it better rests on serious solid foundations. Foundations of the kind that makes theoretical physics such a great science. The papers today do not really help in gathering enough people to look into the details in order to find more mathematical support for or against the dS landscape. Vafa and friends created the academic, intellectual space to investigate this and that is great! We should be grateful for that. His move was necessary since too many papers are written about "stringy inspired EFT's". Whereas really listening as to how string theory constrains EFT's seems less popular, although much more relevant. It is less popular since it is simply more complicated. But, in the long run, will be more rewarding. Many things that may seem to have crawled out of the Swamp today, could very well fall back in later.

    --END QUOTE--
     
    Last edited: Aug 29, 2018
  7. Aug 29, 2018 #67
    The following paper talks about attempts to obtain de Sitter vacua in string compactifications.

    De Sitter vs Quintessence in String Theory

    https://arxiv.org/pdf/1808.08967.pdf
     
  8. Aug 30, 2018 #68

    Urs Schreiber

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    Yeah, that's paper 1 of 5 discussed in the previous message.
     
  9. Sep 13, 2018 #69

    Urs Schreiber

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    Danielsson today in arxiv:1809.04512 linking the known instability of de Sitter in field theory (e.g. Rajaraman 16) to the issues with alleged dS string theory vacua.

    (He must have been following my comments here... ;-)

    Maybe there'll be more discussion here.
     
  10. Sep 19, 2018 #70

    Urs Schreiber

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    Today Moritz-Retolaza-Westphal arxiv.org/1809.06618 still aren't convinced of Kallosh-Linde's arguments for saving KKLT arxiv.org/1808.09428. Independent of how this debates turns out, the key point of Moritz-Retolaza-Westphal is simple: You gotta stick to precise arguments.

    (possibly more discussion here)
     
  11. Sep 20, 2018 #71

    Urs Schreiber

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    Further careful checks of the KKLT construction today, and further doubts that it can work: arxiv.org/1809.06861.
    Dngy3rgW4AAAvgD.jpg
     
  12. Sep 20, 2018 #72

    Fra

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    Thanks for monitoring this frontier and highlighting it here! It is fascinating to see this happening. I cant wait to see what the dual to this twist will be.

    /Fredrik
     
  13. Sep 25, 2018 #73

    Urs Schreiber

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    Today the reply from Kallosh and Linde: http://arxiv.org/abs/1809.09018 Am unsure about their logic. It sounds like saying it's not their problem if the embeddings into 10d of their model doesn't work. Instead they feel free to further modify the 4d model.

    Thomas von Riet comments (here): "it is distraction from the essence. Their original paper needs to be addressed and not some detail about a 4d SUGRA description failing at some far point in moduli space"
     
  14. Oct 14, 2018 at 5:51 AM #74
    I have avoided this topic since it is a little distant from my interests, but some string doubters excited that "Vafa's conjecture" might falsify string theory, provoked me to look at it again. The reason for the excitement is that the conjecture creates new constraints regarding dark energy, inflation, and so on. In particular, it is being reported that "the Higgs field also has properties that should actually be forbidden by Vafa's conjecture". The people who did the research surely consider this a reason to amend the conjecture, but for the string skeptics, the excitement is that maybe the Higgs boson already falsifies string theory.

    What does the paper say is actually inconsistent with the "dS swampland conjecture" as currently formulated? The standard model Higgs... plus quintessence, and with only a minimal coupling between them. In the discussion, they link to some papers which already propose milder versions of the conjecture... But what interests me more is a related paper from Korea, which points out that a similar dS extremum exists for the pion scalar potential too.

    To me this seems ripe for producing an outright counterexample to the conjecture as it stands. The Koreans consider (their eqn 26) a scalar potential involving the pion field and the quintessence field. Well, you should be able to get pions from a brane stack, and Vafa proposed that quintessence could just be a modulus associated with a Calabi-Yau handle. It doesn't sound that complicated (for a string theory vacuum): maybe strings compactified on a torus with one or two holes, with a brane or two wrapped around one of the them. So one hole has the pion branes wrapped around it, and the other hole provides the quintessence modulus...
     
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