The Backwards Image of Yukawa and Feynman

The first episode of a series of my essays on Richard Feynman [1] is about the photo of Yukawa and Feynman that appeared backwards in Physics Today [2]. Last year I planned to make a book [3] by including the above series of essays, and wanted to use that photo by getting permission from AIP. So I searched it at AIP Emilio Segrè Visual Archives.

Bravo! The image was kept as printed previously [4], in spite of the fact that Peter Lee pointed out the backwards printing in a letter to the editor of Physics Today [5].

These days the normal image is simply gotten from the backwards one by a photo editing program, so that I was afraid that it might have been saved as the normal image. Permission to use the photo can be made easily at the Web site of Emilio Segrè Visual Archives. However, if the photo had been kept as the normal image, it should have been necessary for me to make special contact with them to get permission of the modified use of it, i.e., the use of horizontally flipped image as printed in [2] by describing the reason that my essay refers to . . .

By the way, you can also see the same photo printed backwards in the books [6] and [7] (in fact, the first mention of the photo in my essay is made of the one in [6]).

1. T. Tabata, What Little I Can Talk about Feynman, The Web site of IDEA (1999) [improvements and corrections made in the version included in [3] are not yet made in the Web version].
2. L. M. Brown and L. Hoddeson, Physics Today Vol. 35, No. 4, p. 36 (1982).
3. T. Tabata, Passage through Spacetime: Random Writing of a Physicist (Jupiter, Tokyo, 2009) [not for sale].
4. Catalog #: Hayakawa Satio D1, Emilio Segrè Visual Archives.
5. P. H. Y. Lee, Physics Today, Vol. 35, No. 9, p. 13 (1982); for a minor correction, see T. Tabata and P. H. Y. Lee, ibid. Vol. 36 No. 4, p. 90 (1983).
6. J. Gleick, Genius: The Life and Science of Richard Feynman (Pantheon, New York, 1992; paperback edition, Vintage, 1993) p. 7 bottom of insert between pp. 118 and 119.
7. J. Mehra, The Beat of a Different Drum: The Life and Science of Richard Feynman (Clarendon, Oxford, 1994) plate 7 between pp. 320 and 321.

The Unit "Dirac"

About twenty years ago, I asked one of my colleagues what was the unit "Dirac" for. He, a competent physicist, thought about it for a while in earnest, and replied ashamedly that he did not know. My question was a joke borrowed from the following passage in Ref. 1:

Dirac's taciturn and retiring behavior are famous; in his days at Cambridge, a unit of volubility called a dirac meant one word per year.

Reading a new biography of the Nobel-winning physicist P. A. M. Dirac (Ref. 2), I found a different definition of the unit Dirac, i.e., one word per hour. This definition is more realistic than that in Ref. 1, but the latter, which exaggerates Dirac's taciturnity too much, is funnier than the former and too good to be discarded.

The relevant description in Ref. 2 is quoted in Ref. 3 under the title "Unit of taciturnity." Surely the unit commemorates Dirac's taciturnity, but it should be called a unit not of taciturnity but of volubility or talkativeness, because the number of words per unit time is smaller for the person of higher taciturnity.

[A similar story was posted earlier in Japanese: http://bit.ly/cf6ki0.]

References

1. N. Calder, The Key to the Universe (Viking, New York, 1977).
2. G. Farmelo, The Strangest Man: The Hidden Life of Paul Dirac, Quantum Genius (Faber and Faber, London, 2009).
3. Unit of taciturnity: The Dirac, Laudator Temporis Acti (January 26, 2010).