# Mazur's unpublished manuscript on primes and knots?

The story of the analogy between knots and primes, which now has a literature, started with an unpublished note by Barry Mazur.

I'm not absolutely sure this is the one I mean, but in his paper, Analogies between group actions on 3-manifolds and number fields, Adam Sikora cites

B. Mazur, Remarks on the Alexander polynomial, unpublished notes.

He also cites the published paper

B. Mazur, Notes on étale topology of number fields, Ann. Sci. Ecole Norm. Sup. (4)6 (1973), 521-552.

I suppose an expert would recognize as relevance of this paper, but I don't see that even the word "knot" ever occurs there.

[My Question] Does anyone have a copy of Mazur's note that they would share, please? If not, has anyone at least actually seen it.

By the way, already years ago, I asked Mazur himself. I watched him kindly search his office, but he came up dry.

I realize that whatever insights the original note contains have doubtless been surpassed after c. 40 years by published results, but historical curiosity drives my desire to see the document that started the industry.

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When I asked him, he gave me a copy of this fascinating article: books.google.com/… –  Thomas Riepe Dec 13 '10 at 22:08
The most au courant version of this analogy, which I learned from Deninger (though I don't know whether it originates with him) is that a number field is like a 3-manifold with a flow, in which the primes are the closed orbits! –  JSE Mar 6 '11 at 19:44
@JSE: some written references would be highly appreciated.  –  Chandan Singh Dalawat Mar 7 '11 at 3:41

This showed up in my snail-mail today, so I'm sharing the wealth:

http://ifile.it/rodc5is/mazur.pdf

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Any interest in a stone-soup effort to Tex the beast? Ten volunteers, 3 pages each, say? –  David Feldman Feb 17 '11 at 4:14
That's a really good idea! Maybe open a meta for it? In any case, you can count me in. –  Dror Speiser Mar 4 '11 at 12:56
I also would like to help out with this. I didn't see a meta link for it though. If someone starts this up, let me know! –  jd.r Mar 6 '11 at 19:21
*"link" should be "thread" in the above comment. –  jd.r Mar 6 '11 at 19:22
Hi Anton, I have re-upped: ifile.it/t5qp34u NB Since Mazur is distributing this preprint now from his own page, I don't plan trying to keep this fresh in perpetuity. –  David Feldman Oct 22 '11 at 6:27


Sadly, I don't have a copy of the unpublished note, but at least I can tell you what the published paper has to do with knots.

In that paper, Mazur shows that etale cohomology for Spec($\Z$) satisfies a sort of Poincare-duality as known for 3-dimensional manifolds. So, one might consider Spec($\Z$) as a 3-dimensional manifold. As its fundamental group is trivial, it should be after Poincare-Perelman the 3-sphere. Primes should be closed submanifolds in it and as the fundamental group of $\F_p=\Z/p\Z$ is $\hat\Z$, one might consider primes as circles embedded in $\S^3$, that is, as knots.

The analogy goes a lot deeper and I've written a blog-post about it some time ago (with references to Mazur's paper and follow-ups) :

Mazur's knotty dictionary

I've also given a talk about it, intended for a general public, last year. The slides are sadly in Dutch, but perhaps they convey what I was trying to tell : (34Mb download though ...)

What does a prime number look like?

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Dear Lieven, thanks for the answer, and great to see you back! –  Hailong Dao Dec 13 '10 at 21:48

Thanks to this MO question, the paper Remarks on the Alexander Polynomial is now available on Barry Mazur's website.

Gratuitous addendum. For a recent overview, see

Morishita (Masanori), Analogies between prime numbers and knots, Sūgaku 58 (2006), no. 1, 40–63.

An English translation has appeared in

Sugaku Expositions 23 (2010), no. 1.

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