Single Superfield Inflation: The Trailer

This is amazing. (Via Bob McNees and Michael Nielsen on Twitter.)

Backstory for the puzzled: here is a nice paper that came out last month, on inflation in supergravity.

Inflation in Supergravity with a Single Chiral Superfield
Sergei V. Ketov, Takahiro Terada

We propose new supergravity models describing chaotic Linde- and Starobinsky-like inflation in terms of a single chiral superfield. The key ideas to obtain a positive vacuum energy during large field inflation are (i) stabilization of the real or imaginary partner of the inflaton by modifying a Kahler potential, and (ii) use of the crossing terms in the scalar potential originating from a polynomial superpotential. Our inflationary models are constructed by starting from the minimal Kahler potential with a shift symmetry, and are extended to the no-scale case. Our methods can be applied to more general inflationary models in supergravity with only one chiral superfield.

Supergravity is simply the supersymmetric version of Einstein’s general theory of relativity, but unlike GR (where you can consider just about any old collection of fields to be the “source” of gravity), the constraints of supersymmetry place quite specific requirements on what counts as the “stuff” that creates the gravity. In particular, the allowed stuff comes in the form of “superfields,” which are combinations of boson and fermion fields. So if you want to have inflation within supergravity (which is a very natural thing to want), you have to do a bit of exploring around within the allowed set of superfields to get everything to work. Renata Kallosh and Andrei Linde, for example, have been examining this problem for quite some time.

What Ketov and Terada have managed to do is boil the necessary ingredients down to a minimal amount: just a single superfield. Very nice, and worth celebrating. So why not make a movie-like trailer to help generate a bit of buzz?

Which is just what Takahiro Terada, a PhD student at the University of Tokyo, has done. The link to the YouTube video appeared in an unobtrusive comment in the arxiv page for the revised version of their paper. iMovie provides a template for making such trailers, so it can’t be all that hard to do — but (1) nobody else does it, so, genius, and (2) it’s a pretty awesome job, with just the right touch of humor.

I wouldn’t have paid nearly as much attention to the paper without the trailer, so: mission accomplished. Let’s see if we can’t make this a trend.

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28 Responses to Single Superfield Inflation: The Trailer

  1. Garrett says:

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  2. Hector says:

    But it’s far from settled whether a multiverse even exists. For example, Katherine Freese seems to suggest that she’s confident eternal inflation is incorrect:
    http://www.simonsfoundation.org/…/20140722-in-search…/

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  3. Sean Carroll says:

    Hector, this has nothing to do with the multiverse or eternal inflation. You can have inflation without those.

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  4. Amarashiki says:

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  5. Hector says:

    Sean,

    Is there a consensus on whether eternal/chaotic inflation is consistent with current experiments? Will PLANCK be able to refute or be in-line with eternal inflation? It’s just confusing when one physicist says one thing, and another physics says the opposite, yet both have access to the same experimental data.

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  6. Sean Carroll says:

    Different versions of inflation (eternal, non-eternal, chaotic, natural…) are all just “scenarios,” corresponding to many possible specific models. It’s very hard to imagine any one experiment decisively ruling them out. In the real world, accumulated evidence will either make such models increasingly less plausible, or provide support for one of them and make it seem likely.

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  7. GerardO says:

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  8. Pingback: Weekly Buzz: 8/18/14 | Jesus & Dawkins

  9. Halfonse says:

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  10. Milkshake Number 4 says:

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  11. Avattoir says:

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  12. Mike Dziuba says:

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  13. cosmonut says:

    Hector:

    If the bicep results hold up, then all we will know is that SOME kind of inflation happened.

    It is doubtful if we will ever be able to tease apart the dozens of different inflation models as they primarily differ in their predictions about things happening way beyond the observable universe.

    The mutually contradictory statements among physicists reflects this fact.

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  14. OMF says:

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  15. Hector says:

    Well then, I guess since it seems as though, experimentally, we won’t be able to find out which (among the many) inflation models actually happened, we will have to rely upon the ultimate theory that unifies gravity, quantum mechanics, space, time, and all other interactions in order to help us.

    And I do believe that once we find such a theory, it will also allow us to explain the “Measurement Problem” that Sean religiously believes is solved because of many worlds. How many parallel universes can dance on the head of a pin??

    I, myself, don’t care about all this measurement problem fluff. What we need are more experiments and less people being paid by student tuition thinking about which quantum philosophy is better. At the end of the day, quantum mechanics is a mathematical model that approximates or simulates the reality of our experiments. Going deeper and deeper, higher and higher energies, smaller and smaller length scales, experiments will lead the way towards better and better *mathematical* models that simulates the reality of our experiments, and we can’t expect anything better than that. Anything else is based on an assumed and *unprovable* assumption or belief about reality and science itself.

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  16. Cosmonut says:

    Hector,
    Spot on about that.

    String theory was supposed to be the ultimate theory that would unify all of physics and make definitive predictions about things like the inflaton field and so on, but its been very unsuccessful in that respect so far.

    I myself was much confused by all the conflicting claims about inflation in the media, so started reading some papers.

    The method of coming up with inflation models seems to be:

    * Pull a scalar field potential function out of your ass
    * Tweak/add parameters until your model can reproduce well known facts from observation
    * If it still doesn’t work, throw in more scalar fields, more complex potential functions and so on

    Its no wonder that there are dozens of models all making the same “generic predictions” (they are engineered to do that) and you have a lot of stupid hand waving based on hypothetical stuff beyond the observable universe and “anthropic arguments”.

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  17. Hector says:

    Yeah, kind of like epicycles. Those epicycles weren’t pretty, but they did agree with the observations at the time.

    I bet I can find a mathematical model that reproduces inflation, but where there’s only one universe. Such a model would ask the questions, “Why this universe and not some other one?” and “If this is the only universe, and it had a beginning in time, what got it started?”, and that would lead to the conclusion of a God or supernatural being that created the universe. So sure, why not? After all, Sean claims the universal applicability of Schrodinger’s equations naturally leads to the existence of parallel universes (many world theory), which cannot be observed. He also responded to Brian Green who asked, during this quantum debate I saw, if these parallel universes are completely unobservable, than how is believing in this different from believing in a god? He responded that if there was an equation for God, he might believe. Well, this mathematical model mentioned above naturally leads to the existence of a supernatural being that created the universe, because there’s only one universe. So, what’s the difference?

    So this whole parallel universes and measurement problem stuff is just fluff. It’s a mathematical model that you use to calculate stuff and invent new technology.

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  18. Mikkel Rumraket Rasmussen says:

    “Such a model would ask the questions, “Why this universe and not some other one?” and “If this is the only universe, and it had a beginning in time, what got it started?”, and that would lead to the conclusion of a God or supernatural being that created the universe.”
    No, it wouldn’t.

    Why the heck would there being just one universe automatically entail god? It wouldn’t. How do we know that the origin of time itself requires a cause? We don’t. How do we know that causes of universes need or have to be supernatural? We don’t. How do we know that, even if supernatural beings exist, that they can create universes? We don’t. There’s nothing “natural” about your unsupported inferences here. So much is assumed without any justification at all.

    By the way, what’s with all the downvotes of comments in this thread? It’s not like there’s anything controversial said as far as I can gather.

    Thumb up 6 Thumb down 10

  19. kashyap vasavada says:

    Sean,
    These debates are interesting. But please discontinue this method of allowing people to down vote and dim the comments. It is amusing to note that your comments also have been heavily voted down! First of all, this is against age-old scientific principle that one should hear both sides. Even great scientists like Einstein and Heisenberg have been proved wrong! The other point is that one does not know qualifications of the voters. They may not even know high school physics and simply may not have understood the comment. A recent example was a heavy down vote against a nice engineering video given by Walker Guthrie in the previous thread. Although it had nothing to do with quantum mechanics, it was a nice classical engineering demo of quantum particle in a box. I think it was cute. Many other frank criticisms of the viewpoints have been voted down. By the way, this down voting has not stopped totally unscientific wild speculations (in my opinion!!) appearing in the comments. But it is fine with me!

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  20. Hector says:

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  21. Fine Tuned says:

    These supergravity models of inflation are extremely fine tuned and ad hoc.
    There were a bunch of recent papers by Kallosh and Linde that just threw the rules of effective field theory out the window and came up with a bunch of different inflation models in supergravity, built by random functions, and now a bunch of sheep just copy and follow. Although I do give Ketov and Terada some credit for (briefly) admitting in their conclusions that these models are fine tuned.

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  22. John Barrett says:

    The problem with modern physics these days is that it is thought that the time for new discoveries to be made is almost over. If what we have now to describe modern physics is actually the best way to describe it, then it may actually be coming to a close. Then we should just shut down the physics department and call it quits? “Fluff” may actually be the only new discoveries out there to be had. To keep the department alive, it requires people sitting around debating the finer points of the interpretations and philosophy that comes with it. Without those people, it would already be dead! Hopefully, one day those incites will lead to a breakthrough that will take us beyond the standard model. Maybe, one day those questions can be laid to rest and prove to us that we actually do have the final answer. The fact of the matter is that if you don’t like “fluff” then your most likely not going to like anything else left to be discovered in modern physics.

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  23. Hector says:

    “Fluff” may actually be the only new discoveries out there to be had.

    You’re joking, right? I can’t wait for the day when parallel universes are discovered. I will throw a big party.

    Like or Dislike: Thumb up 1 Thumb down 2

  24. John Barrett says:

    “You’re joking, right? I can’t wait for the day when parallel universes are discovered. I will throw a big party.” – Hector

    In order to do that you would need to discover how to harness the total energy of the Sun into one single location in order to transverse hyperspace. There is no known power source that could accomplish this goal or a material that would be able to withstand it. Other than that, modern physics could accomplish this goal, but it is just way out of our technological grasp or may be technologically impossible altogether. This was a real knee slapper…

    Like or Dislike: Thumb up 0 Thumb down 0

  25. Hector says:

    You’ve been watching too many Sliders episodes. You cannot traverse through a wormhole. You need “exotic matter” to hold the wormhole open. “Exotic matter” violates certain energy conditions, so it cannot exist.

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  26. John Barrett says:

    I have hardly seen any Sliders episodes. I read about it in a book about theoretical physics. It has been thought that a stable wormhole from a natural gravitational singularity could work by it having a high rotation or be in the presence of a strong electromagnetic field. If there was no gravitational singularity, then all it would take would be two dielectric plates sitting next to each other and given enough power. There would be no gravitational well, so countering it wouldn’t be needed.

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  27. Cartoon-Hollywood physics in yo’ face!

    Whoopee!

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  28. GerardO says:

    Who keeps barging into this blog en masse to give comments a Thumbs Down? This seems like a pointless and irritating “feature” to add to this site. Sean?

    Like or Dislike: Thumb up 3 Thumb down 4