Talk:Paul Dirac

Internal links and syntax

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Undue emphasis on religion.

The view on religion section is, IMO, too large compared to its role in Dirac's life. It is 4 times longer than the section on Honors. That seems out of whack. Johnjbarton (talk) 22:55, 30 December 2023 (UTC)

Helikon vortex separation process

The current article claims Dirac worked on centrifuges in 1934. This seems unlikely. We should have a citation and and explanation of the context since such work is out of context for this period of Dirac's career.

Two sources date as joining the UK Tubes project which developed the centrifuge:

• Kragh, Helge. Dirac: a scientific biography. United Kingdom, Cambridge University Press, 1990.
• PAUL DIRAC: THE ATOMIC CENTRIFUGE AND THE TUBE ALLOYS PROJECT By DANIEL P. VROBEL

There is comment in the Kragh book about something in "Chapter 6" which I cannot access. Johnjbarton (talk) 16:47, 11 January 2024 (UTC)

@Reaper1945 Thanks for the ref, but I still dispute the date. The ref does not say anything about when Dirac did this work. Johnjbarton (talk) 19:56, 11 January 2024 (UTC)

Can someone help with the source code for harvnb references? Farmelo explains Dirac's isotope separation experiments on p.248-249, and then confirms the 1934 by saying on p.249 that "During a visit to Cambridge in May 1934, Wigner saw the apparatus and asked Dirac questions about it,". I tried to cite these two pages in the article, but my cite only shows the text of p.248 and says that p.249 is unavailable. Can someone fix this? Dirac66 (talk) 02:04, 13 January 2024 (UTC)

I guess your harvnb is not the problem. Google Books does not have the preview for Farmelo. So no content for you. No worries, Google Books links are a gift that only work sometimes.

IMO it would be great if the article could clarify why an all time genius in QM theory would be Lucasian Professor of Mathematics one year, invent an isotope separation, the cosmology? Seems like there would be a nice story even in one sentence that would explain why he would work on separation before WWII. Johnjbarton (talk) 02:12, 13 January 2024 (UTC)

Re harvnb I tried adding quote= after my citation and it worked (to my surprise).

And re Dirac's varied interests at Cambridge, I think most people are interested in more than one topic. Also separating an element into isotopes would have been a challenge of interest as soon as isotopes were discovered. This does not imply that he foresaw the eventual military application. Dirac66 (talk) 23:03, 14 January 2024 (UTC)

Puffery

@Reaper1945 Hi. Thanks for your edits, but I plan to make changes. Some of the claims you added recently are simply too fantastic to be correct. I will explain in edit summaries and we can discuss it here. Johnjbarton (talk) 01:33, 22 June 2024 (UTC)

Too fantastic in what way? Reaper1945 (talk) 01:42, 22 June 2024 (UTC)

The idea that Feynman "popularized" his path integral formulation of QM for example.

In addition the article, like other biographies I have to say, tends to present concepts introduced by one scientist then later developed by others is somehow "owned" by the first one. So squeezed light states have hundreds of important contributions of which Dirac's is certainly notable, but to me the article reads like he invented the whole field himself. Dirac was a genius but not superhuman. Ok maybe a little superhuman ;-) Johnjbarton (talk) 02:05, 22 June 2024 (UTC)

I don't mind the tweaking, more so I edited the information in and gave all the sources so anyone could better refine it from its initial raw form. A few more sources are added that better explain Dirac's influence on the areas in that section. Reaper1945 (talk) 02:07, 22 June 2024 (UTC)

I corrected this but @Reaper1945 reverted it. Why?

• Dirac was the first to study anti-de Sitter space (AdS)"

The source does not support this claim. Johnjbarton (talk) 13:59, 22 June 2024 (UTC)

@Reaper1945 I appreciate what you are trying to do, but sources for the influence of someone as famous and well, influential, as Dirac should be historical reviews. Poorly or uncited recent physics papers are not reliable sources for history. In addition to their lack of scholarship on the history, these papers have various motivations to exaggerate Dirac's work for their own purposes. Johnjbarton (talk) 14:44, 22 June 2024 (UTC)

More of a universal fact that's agreed upon by academics that Dirac's 1933 paper directly led and gave the ideas for Schwinger's and Feynman's work. Regardless of that, I don't see why the "Dirac path integral" should be removed having been explained and claims no further credit over Feynman's work. Reaper1945 (talk) 15:34, 22 June 2024 (UTC)

The issue with the "Dirac path integral" was the source:

• Hari Dass, N. D. (2020-03-28). "Dirac and the Path Integral". arXiv:2003.12683 [physics.hist-ph].

Unpublished, with one citation in English from a thesis. Johnjbarton (talk) 16:54, 22 June 2024 (UTC)

Your claim:

• "...Dirac's 1933 paper directly led and gave the ideas for Schwinger's and Feynman's work."

is the kind of wording that I object to. Dirac did not give "the ideas" to two Nobel laureates for their work. They built upon Dirac's work, were influenced by it, etc. but they had their own ideas. Johnjbarton (talk) 17:00, 22 June 2024 (UTC)

However it is put, Dirac's work laid the foundations for their work, that doesn't necessarily mean he completely "owns" it, but he certainly laid the foundations for it in his work between 1932 to 1933. Reaper1945 (talk) 16:03, 23 June 2024 (UTC)

Yes, that kind of wording is fine. Johnjbarton (talk) 17:10, 23 June 2024 (UTC)

Feynman's approach is ultimately his own, but it wouldn't do harm to mention Dirac's work as the foundation for his work is all. Reaper1945 (talk) 17:23, 23 June 2024 (UTC)

For example, even Feynman apparently said to Dyson that "I don't know what the fuss is all about—Dirac did it all before me." Reaper1945 (talk) 17:24, 23 June 2024 (UTC)

That might be an interesting tidbit in a Feynman bio, but assessments of scientific impact should rely on historians or on peer citations, not on personal off-the-cuff remarks. Johnjbarton (talk) 18:14, 23 June 2024 (UTC)

The paragraph as it finally was seemed fine, it did serve as a foundation, basis, or however else one wants to put it, for the work of Schwinger and Feynman, as noted in the numerous sources, it's not like it's saying he was the one who created both concepts on his own, but he certainly did lay the foundations for them, and this is acknowledged by the sources given, doesn't diminish the hard work of those two. Reaper1945 (talk) 18:21, 23 June 2024 (UTC)

@Reaper1945 again you are making changes to puff Dirac. Please read more on the history of quantum electrodynamics and field theory. A lot of people were involved. Johnjbarton (talk) 04:10, 28 July 2024 (UTC)

There's four sources, what do you mean read? So, is Duck's and Sudarshan's chapter titled "invention of quantum field theory" puffery as well. Sorry but if reliable sources say so, and agree upon so, then they are so. Feynman and whoever else worked on quantum electrodynamics far later than Dirac, and I could list a thousand sources more in support of Dirac's fundamental position as founder of quantum electrodynamics and quantum field theory. Reaper1945 (talk) 04:17, 28 July 2024 (UTC)

To quote https://www.nobelprize.org/prizes/physics/1965/summary/

• The Nobel Prize in Physics 1965 was awarded jointly to Sin-Itiro Tomonaga, Julian Schwinger and Richard P. Feynman "for their fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles".

No one gets a Nobel prize for work that someone else "established." Dirac's role does not need to be overblown to give him due credit. Johnjbarton (talk) 04:44, 28 July 2024 (UTC)

His 1927 is cited by multiple reliable sources as the inception of quantum electrodynamics/quantum field theory, furthermore "fundamental work" does not mean the founding of, it just means significant contributions to merit awarding. Is it puffery to announce that Einstein created relativity when those before him, such as Poincaré paved the way for him, or those after him who work on it? Hardly puffery. Reaper1945 (talk) 05:00, 28 July 2024 (UTC)

The current wording is

• Dirac laid the groundwork for both quantum electrodynamics and quantum field theory.

which I think is accurate and equivalent to "the inception of". To me "establishing" as it is appears in science histories implies a long, dominating role which is difficult to square with the amount of work by others needed to bring Dirac's inception to fruition. Johnjbarton (talk) 05:06, 28 July 2024 (UTC)

Dirac's equation is cited as being the first to combine special relativity and quantum mechanics. While Dirac's paper in 1927 is the first to coin quantum electrodynamics and the first to cover quantum electrodynamics, and as the inception of quantum field theory, which is stated in the last of the four cited sources. Reaper1945 (talk) 05:11, 28 July 2024 (UTC)

Paragraph on Dirac's Lagrangian paper.

The short paragraph on Dirac's Lagrangian paper keeps being changed. I removed it per WP:BRD. My version:

• Dirac wrote an influential paper in 1933 regarding the Lagrangian in quantum mechanics. The paper served as the basis for Julian Schwinger and his quantum action principle, and laid the foundations for Richard Feynman's development of a completely new approach to quantum mechanics, the path integral formulation.

I based my version on the Debnath ref. The changed version:

• Dirac wrote an influential paper in 1933 regarding the Lagrangian in quantum mechanics. The paper served as the basis for Julian Schwinger and his quantum action principle, and laid the foundations for Richard Feynman's forming and completion of the path integral formulation of quantum mechanics.

In my opinion the changed version is hard to read and improperly implies that Feynman merely tidied up Dirac's work.

References

Johnjbarton (talk) 18:19, 23 June 2024 (UTC)

Here is the Debnath ref content:

• In thesame year, Dirac published his pioneering work on Lagrangian quantum mechanics which became the foundation of Richard Feynman’s (1918–1988) completely new approach to modern quantum electrodynamics based on the Feynman path integral.

Johnjbarton (talk) 18:21, 23 June 2024 (UTC)

Debnath 2013 – "Dirac published his pioneering work on Lagrangian quantum mechanics which became the foundation of Richard Feynman’s (1918–1988) completely new approach to modern quantum electrodynamics based on the Feynman path integral."

Roland et al 2017 – "Dirac published a short paper on this subject in a Soviet journal in 1933, in which he writes the expression we know today of the path integral and argues that summing over all paths is analogous to the quantum theory. In Dirac's formulation this was only an analogy, not a complete theory. A historical puzzle, not easy to solve given Dirac's rather introvert character, is why he stopped there and did not proceed to the next logical step, namely the complete formulation of the quantum theory as the sum over classical trajectories. This was done by Feynman in 1948" Reaper1945 (talk) 18:28, 23 June 2024 (UTC)

Milton 2000 – "Schwinger recognized that the systematic approach of Dyson-Feynman was superior in higher orders. So by 1949 he replaced the Tomonaga-Schwinger approach by a much more powerful engine, the quantum action principle. This was a logical outgrowth of the formulation of Dirac, as was Feynman’s path integrals; the latter was an integral approach, Schwinger’s a differential." Reaper1945 (talk) 18:58, 23 June 2024 (UTC)

Good, these are all fine. I think these support my text and not a version in which Feynman only gets "forming and completion of the path integral formulation of quantum mechanics." As the Roland ref points out, writing a mathematical path integral (Dirac) is not a complete formulation of QM (Feynman).

Rather than workout fine details of words, maybe we should expand the paragraph in a small section on the Lagrangian work. Dirac's Lagrangian paper had more impact than his work on string theory or gravity. Johnjbarton (talk) 19:14, 23 June 2024 (UTC)

I created the "other significant work" section so as not to blow up other sections of his contributions since there's just so many to put all into a couple of sections. There's some other sources regarding the 1933 paper, for example, "The groundwork for the path integrals as they are understood to-day was prepared in 1933 by Dirac" and goes on how to Feynman then went about it. Another is by Roger Penrose, "The procedure which lies at the background of many modern thereotical approaches to the subject is that of path integrals, based on an original idea by Dirac in 1933 and developed by Feynman into a very powerful and effective technique for QFT." Putting it as "it laid the foundations for Feynman’s formation and completion of the path integral formulation of quantum mechanics" isn't taking anything away from Feynman, based on all the sources it's agreed that Dirac's work is the origin of path integrals regardless, but it was Feynman who refined it and actually completed it into a full working theory, but the initial ideas were right there in 1933. Roland agrees that it originates in 1933, but Dirac for whatever reason didn't take the next step, and the complete method as a whole was done by Feynman in 1948. Reaper1945 (talk) 19:54, 23 June 2024 (UTC)

John W. Negele also notes that "The essence of the path integral was introduced in a germinal paper by P.A.M Dirac (1933) and developed extensively by R.P. Feynman (1948,1949,1950)." Reaper1945 (talk) 20:32, 23 June 2024 (UTC)

References

In my opinion you are conflating "path integral", an important mathematical advance by Dirac and "path integral formulation", equivalent to but ultimately more useful than Schrodinger's and Heisenberg's, developed by Feynman. Johnjbarton (talk) 21:41, 23 June 2024 (UTC)

Would be fine to reinstate your old version. "Laid the foundations for Feynman’s own development of the path integral formulation" or however else. Reaper1945 (talk) 15:46, 24 June 2024 (UTC)

Thank you. Again, I appreciate your work here. Johnjbarton (talk) 16:14, 24 June 2024 (UTC)

No problem, the Debnath and Roland ones are good, so I just removed the arXiv one since the other two practically explain it already. Reaper1945 (talk) 16:42, 24 June 2024 (UTC)

Other significant work

The paragraph on Fermi's Golden Rule and on time-dependent perturbation theory is about Dirac's 1927 paper "The quantum theory of the emission and absorption of radiation” which is also the one that originated quantum electrodynamics. It seems to me that the 1927 paper should be discussed all in one place. Johnjbarton (talk) 18:06, 25 June 2024 (UTC)

I was thinking of creating a separate quantum electrodynamics section due to just how much influence he had as its founder and subsequent work. Just a lot in general for all the work he did. Reaper1945 (talk) 23:57, 25 June 2024 (UTC)

Consider instead a section on his paper and it multiple consequences or influences. I think that would be more interesting and true to a biographical style. Johnjbarton (talk) 02:11, 26 June 2024 (UTC)

I'll see what fits best with paying attention to each important aspect of the paper. Reaper1945 (talk) 03:25, 26 June 2024 (UTC)

There were some other good sources, but I'll have to find them again. Reaper1945 (talk) 03:25, 26 June 2024 (UTC)

Misplaced paragraphs in FSU/Miami section

I can see that the page is being actively edited so I didn't want to just barge in, but I noted that there are three misplaced paragraphs in the "Florida State University and University of Miami" section. Specifically, paragraphs 2-4 refer to work he did before ever coming to Florida. So I propose moving those earlier in the article, perhaps in the "University of Cambridge" section, but suggestions would be appreciated.

Also, the article doesn't seem to make clear (at the beginning anyway) that Dirac was only jointly at Miami and FSU during 1969-1971, and in 1971 started working at FSU full-time, as explained in the citations already in the article. If you read it closely I guess this is implied...but I'd like to tidy that up and make it clearer. If anyone agrees, feel free to make these changes; if not I'll wait until the other matters discussed above are resolved. Or of course you can tell me why I should not change them, and so on....happy editing! Qflib (talk) 14:43, 28 July 2024 (UTC)

I moved the content and fixed up the refs, but the rest please follow through if you have sources. Johnjbarton (talk) 23:23, 28 July 2024 (UTC)

Done. I was wrong about 1971 though; looks like he wasn’t full time at Florida State until 1972. Qflib (talk) 17:49, 29 July 2024 (UTC)

Excellent thanks! Johnjbarton (talk) 21:28, 29 July 2024 (UTC)

Missing content on Dirac's time in Princeton.

Several sources mention Dirac's time at the Institute for Advanced Studies, Princeton. Pais places him there in 1936 and 1946, 1947, 1958, 1962; the Pais book has a photo of Dirac with Oppenheimer and Pais. At least on publication lists IAS as his institution. Johnjbarton (talk) 17:04, 29 July 2024 (UTC)