The Early Stages of Cosmic Inflation

When asked to cite the article that first presented the theory of the inflationary Universe most cosmologists would probably offer the famous paper published by Alan Guth in 1981.

However, I recently stumbled across a paper by Demosthenes Kazanas that was published (in the Astrophysical Journal Letters in 1980. I hadn’t seen this paper before a few days ago, and I don’t think it is very well known. Here is part of the front page:

You can get the full paper here.

I know that there were other papers floating around in 1980 that got part of the way to the theory of inflation, but this one seems very close to the theory, e.g. talking about exponential expansion in the context of the cosmological horizon problem.

Interestingly, while Guth (1981) has garnered many thousands of citations, Kazanas (1980) has been cited fewer than 300 times.

Does anyone know the story of this paper, and why it has largely  been overlooked by the exponentially-expanding literature on cosmic inflation? And,while I’m on the topic, can anyone suggest other early contributions to the theory that have been similarly neglected? Please let me know through the comments box below.





23 Responses to “The Early Stages of Cosmic Inflation”

  1. Einar H. Gudmundsson Says:

    Dear professor Cole. You might find this of interest:

  2. Shantanu Says:

    You can also find Kazanas own retrospective of this paper
    Again, I think the blame lies on the cosmological community for not doing a thorough literature search. Whenever I get a chance always point people to this paper (although its in vain). Nobody cites papers of people if they don’t show up for the relevant conferences (or nowadays are fb friends of cosmologists). Demos mainly works on AGNs and given that you have been working on cosmology for last 30 years, you can tell me, if you have ever met him in any conference. Anyhow given that so many prizes have been awarded for inflation, its a shame that Kazanas has not been considered for any of these.

  3. Anton Garrett Says:

    Whose law is it that in cosmology the effect is named after the second person to discover or predict it, or at least that the second person gets the glory?

  4. Michel C. Says:

    Who says Inflation is a real phenomenon? It is a collective hallucination in any prize donation…! People tend to look at the fitting part of the piece of the puzzle but they forget all the other sides not fitting and needing many extra missing imaginary pieces.

    The idea of Inflation was not bad at an early stage, but to embrace it in the long run is (was) foolish…

    • telescoper Says:

      Can you please cite the scientific evidence on which you base your conclusion that inflation is a ‘collective hallucination’?

      • Michel C. Says:

        I can fairly say that for an important percentage of physicists, Inflation is more than just a theory.

        Inflation was born out of another idea: a singularity from which space and time emerged in a Big Bang. And there is the allegation of a spontaneous symmetry breaking. Here I don’t have a problem with the symmetry breaking but more about the “spontaneous” part. All this just shows how little is truly known.

        Universes spontaneously popping out from vacuum energy is more akin to sci-fi than science.

        There is a part of fashion and trend in Physics. Fashion, in a sense, is a collective hallucination, though there is a real part to it…

  5. Shantanu Says:

    Just to add, in 2007 DAMTP organized a conference to celebrate 25 years of a similar workshop on inflation and in that meeting Dmeos was the third speaker after Guth and Starobinsky.
    So at least some people know of this work. But its a shame that the Gruber (and Shaw) prize committee overlooked him.
    I suspect its a chain reaction. Young people only follow what they have been told or read in textbooks and don’t bother to do their own research or literature search. I am surprised you came to know of this paper only recently, inspite of been in the field for more than 30 years.

    Note that M. Nauneberger has pointed out that exactly the same thing happened in Chandrasekhar limit where Stoner’s pioneering work, before Chandra was slowly forgotten.

  6. I have to agree with Shantanu here; there are many factors determining whom is cited apart from “published the idea in a major journal”, perhaps even before anyone else. Off the top of my head: people tend to cite colleagues, people with whom they might apply for a job, people who cite them, people they know of know of, people who are famous for other reasons, etc.

  7. There are several papers from Soviet scientists in the 1970s on inflation. Although Starobinsky is relatively well known, there were others (perhaps like Kazanas better known for other things). Why overlooked? Perhaps because they were from Soviet scientists. (I don’t recall where they appeared off the top of my head, but it is certainly the case that Soviet Astronomy was not as well read as, say, MNRAS.) Also, they weren’t trying to solve any of the now well known problems which inflation can solve, but were trying to avoid a big-bang singularity.

  8. John Peacock Says:

    In some sense, the first inflation paper was by Erast Gliner (born 1923 and still around), back in 1965: Soviet Physics JETP, Vol. 22, p.378. He noted that an (unexplained) phase transition from a vacuum equation of state to radiation domination gave a scale factor that is exponential at early times, matching on to radiation domination at what he didn’t call “reheating”. He was most struck by the fact that this removed the big-bang singularity and allowed a model that was eternal in the past. This is what is needed to solve the horizon problem, but that wasn’t emphasised. Still, the idea that a time-variable lambda would be a useful way to start the universe was in place even before the CMB was detected. Surprising perhaps that it took 15 years for people to realise that scalar-field dynamics could supply the mechanism that Gliner wanted.

    • telescoper Says:

      There’s a paper by Bill McCrea in 1948 that says something very similar.

      • John Peacock Says:

        What was the McCrea ref? ADS doesn’t seem to find it.

      • OK, thanks to modern technology, I have The Weight of the Vacuum on my iPad Pro. OK, here it is:

        McCrea, W.H. “Relativity theory and the creation of matter”. Proc. Roy. Soc. A 206, 1087, 562–575 (1951).

        As is often the case, Kragh and Overduin don’t provide the title or the number of the journal. I got those from ADS, so it is there as well. There is a link to an online version, which is accessible to Fellows of the Royal Society, so at least John can read it. 🙂

        According to ADS, it has 111 citations, including the new book by Bernard Jones mentioned here recently. Thus, it seems reasonably well known, and has been cited by many people even better known than Bill McCrea.

    • Both McCrea and Gliner, as well as other “early inflationists”, are discussed in chapter eight of The Weight of the Vacuum by Helge Kragh and James Overduin. I recommend both the book as well as other writings by these two.

  9. telescoper Says:

    David Seery informed me via Facebook that Kazanas gave a talk at a meeting in Cambridge in 2007 in which he discussed his paper. You can find the slides here:

    I had a look at his presentation, and it looks interesting but unfortunately quite a lot of it is corrupted in some way so many of the equations don’t appear properly.

  10. Has Guth ever cited this paper by Kazanas? If not, I think he is the one to be held responsible for this situation. Even if he were initially unaware of it, he could have added citations to later papers.

    • Sarah Bosman Says:

      Most students go all the way up the references chains when hunting for references, so I’m nearly certain that Guth never referenced the 1980 paper.

    • Shantanu Says:

      Guth (and also Linde, Starobinsky) was there in the Cambridge 2007 meeting on inflation, where Kazanas gave a talk. So he should definitely be aware. At any rate he alone is not to be blamed. In 2013 , a prominent cosmologist (usually gives keynote cosmology talks in major conferences) was giving a colloquium talk on tests of inflation and when he mentioned history of inflation, he cited Sato, Starobinsky, Guth, Linde, Steinhardt and Albrecht. I then pointed to him his omission of Kazanas. Yet, I doubt he bothered to look that paper, since that name is always omitted in subsequent talks and also papers.

    • Thats fairly easy to check using ADS, but looking at the citations to Kazanas’ paper, a search for Guth finds no results. So he hasn’t cited it unless possibly in a paper where he is way down the author list.

      Citation history to Kazanas’ paper is interesting, fairly low until 2014 when it took off. Planck and BICEP people were among those who started citing it, maybe the rest follows from there.

    • Shantanu Says:

      I think the blames also goes to the various journal referees and editors for overlooking this faux pas for last 35 years.

  11. From the citation history on ADS, it seems this paper was discovered about four years ago.…241L..59K

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