The Mystery of Yukawa's "New Insight" (Second Revision)

Hideki Yukawa described the climax of the development of his meson theory in his autobiography Tabibito [1]. However, this description is contradictory to the record of his academic presentation made more than a year before the date of climax. Study on this problem has revealed that two factors were responsible to this contradiction.

Yukawa's passage we treat is the following:

The crucial point came to me one night in October. The nuclear force is effective at extremely small distances, on the order of 0.02 trillionth of a centimeter. That much I knew already. My new insight was the realization that this distance and the mass of the new particle that I was seeking are inversely related to each other. Why had I not noticed that before?

"October" in this quote means that of 1934 according to the paragraph that precedes it. Note that his new insight means the realization of the inverse proportionality of the effective distance of the nuclear force (the force that binds neutrons and protons in the nuclei) to the mass of the new particle that mediates this force. Hereafter, we call this inverse proportionality distance-mass relation.

On the other hand, Yukawa made his first oral presentation at a meeting of the Physico-Mathematical Society of Japan held in Sendai in April, 1933. The title of the presentation was "A consideration about the problem of electrons within nuclei," and its abstract includes the following sentence [2]:

From the fact that the electron has the rest mass, we consider that the strength of the interaction decreases rapidly, as the distance between the neutron and the proton becomes large compared with h/(2πmc).

Here, we find that Yukawa used the distance-mass relation already in 1933. Thus, it is contradictory to call the realization in 1934 of this relation "my new insight".

We guess that the following two factors were responsible to the above contradiction.

1. Hisao Sawano of the Assahi Shimbun Company helped the publication of the Japanese version* of Tabibito by editing Yukawa's manuscript [3]. If Sawano's editing had been to such an extent as to change Yukawa's original version into more dramatic one here and there, then Sawano must have modified the passage about the climax without thinking that his change might contradict Yukawa's academic record.

2. In the work of his 1933 presentation, Yukawa treated the possibility that the electron might be the mediator of the nuclear force. This hypothesis included difficulties related to the spin and statistics of the electron. Therefore, Yukawa abandoned the hypothesis soon later. At the same time, he might also have discarded the distance-mass relation. If so, Yukawa had to rediscover it for completing the paper on the meson theory.

There are two accounts that support factor 1. One of them is Yukawa's passage in Ref. 4. He describes there that he finished writing the last section related to the discovery of the meson theory just a few hours before his trip to Europe. Perhaps, Yukawa regularly checked the changes made by Sawano in order for those not to be contradictory to facts. As for the last section, however, it is quite possible that Yukawa's trip to Europe made such a check impossible.

The other account is in the autobiographical book** [5] of Hideki Yukawa's wife, Sumi. She wrote about the days of their visit to Stockholm for Hideki's receiving Nobel Prize. On arriving at a hotel there, they found that many journalists were waiting to interview Hideki. Sumi's passage about part of the interview is as follows:

One of the questions addressed to him was this: "We hear that the Japanese people study sitting on their legs in a straw-matted room. Did you, Dr. Yukawa, write your paper sitting on your legs or sitting on a chair at the Western-style desk?" Hideki thought a little while and said, "I did in neither of those ways. I put my thoughts together at night in bed." This is true. Hideki wrote the paper that brought him Nobel Prize after he had kept thinking many nights at the age of 27 in the year of Shōwa 9 [Note by the translator: 1934]. This story seems to have wrongly come across to Japan. Thus, in Japan they believe that the idea flashed to him in the middle of a night.

This passage makes us think that the description in Ref. 1 about the sudden coming of the crucial point one night was a modification by Sawano, because it resembles the wrong information conveyed from Sweden to Japan. Further, we can consider that Sumi here denied the modified description indirectly. However, we should note Sumi's possible denial refers, in a strict sense, only to "that the idea flashed to him in the middle of a night." This is not relevant to the essential point of the contradiction, because what is contradictory is the content of the "new insight." This content is highly technical and possibly beyond Sawano's ability of rewriting. Therefore, factor 1 alone cannot be the cause of the contradiction.

With regard to factor 2, we find a strong support for this in Ref. 6, where Kawabe and Konuma write as follows:

In the manuscript of the presentation of April 1933, Yukawa corrected his idea in the abstract to read "the actual calculation does not yield this result." Further, in the draft "Bose electron theory" written almost at the same time as the above manuscript (it had been preserved in the file "Manuscripts of seminars and colloquia, 1934–1935"), he wrote, ". . . the term including the Compton wavelength of the electron appears as a kind of phase factor, . . . and, as a consequence, we cannot say the force decreases rapidly with increasing distance."

The above quote clearly shows that Yukawa once fully discarded the distance-mass relation and that the rediscovery of it was necessary.

The words "My new insight" in the quote from Ref. 1 is not the literal translation of the original words. The literal translation of the relevant passage would be as follows:

One night in early October, a thought flashed through my mind. The nuclear force has only an extremely short effective range. It is on the order of 0.02 trillionth of a centimeter. This has been known since earlier time. What I noticed is that this effective range and the mass of the new particle that accompanies the nuclear force would be inversely proportional to each other. Why did I not notice such a thing until then?

If we omit the last sentence in the above passage,*** the thought that flashed Yukawa's mind does not necessarily mean to be new; it can be the revival or the rediscovery of an earlier thought. Thus, the first and the last sentences in the Yukawa's original manuscript, before Sawano's modification, might have been:

In early October, a thought came to my mind. . . . Why did I not examine this again until then?

Then, the passage is a less dramatic depiction of the development of the meson theory but does not contradict to his earlier use of the distance-mass relation. Hideki Yukawa's own autobiography was translated into English, French and German. Therefore, the wrong version of the story modified by Sawano has become famous world over. This is unfortunate. Sumi Yukawa's account quoted above should be informed widely.

(This article owes much to the discussion we have had at Osaka Science Museum among the members of "Citizens' Study Group on Hideki Yukawa.")

Notes

* The Japanese version of Tabibito first appeared as a series of 112 stories in Asahi Shimbun from March to July, 1958.

** The title Kuraku-no-Sono was taken from the street name in Nishinomiya City, where Hideki and Sumi Yukawa lived in the years shortly after their marriage. It has the meaning of "the garden (sono) of joys and sorrows (kuraku)."

*** See also the same passage in the German version [7]: Eines Abends Anfang Oktober hatte ich mit einem Mal die richitige Idee. Die Kernkraft hat eine äußerst kurze Reichweite: nur 2/10-billionstel Zentimeter. Das wußte ich schon vorher. Was ich nun bemerkte, war vielmehr, daß die Reichweite und die Masse der zur Kernkraft gehörenden neuen Teilchen zueinander in umgekehrter Proportion stehen müßen. Warum war ich nicht schon eher darauf gekommen!

References

1. H. Yukawa, Tabibito (The Traveler), translated by L. Brown and R. Yoshida (World Scientific, 1982) p. 202.
2. H. Yukawa, Sūbutu-gakkaisi, Vol. 7, No. 2 (1933) quoted in Nihon-no Buturigaku-shi (History of Physics in Japan) (Tokai University Press, 1978) p. 319 (in Japanese; English translation of the quoted passage by the present author).
3. H. Yukawa, Atogaki (Afterwords) in Tabibito, (Kadokawa, 1960) (in Japanese).
4. H. Yukawa, Hon-no Naka-no Sekai (The World in Books) (Iwanami, 1963) p. 182 (in Japanese).
5. S. Yukawa, Kuraku-no-Sono (Kōdansha, Tokyo, 1976) pp. 349–350 (in Japanese; English translation of the quoted passage by the present author).
6. M. Kawabe and M. Konuma, Butsuri Vol. 37, p. 265 (1982) (in Japanese).
7. Hideki Yukawa: Tabibito - Ein Wanderer, Grosse Naturforscher Band 48, ed. Erwin Müller-Hartmann, transl. Claus M. Fischer, p. 175 (Wissenschaftliche Verlagsgesellschaft, Stuttgart, 1985).

The Mystery of Yukawa's "New Insight" (Revised)

Please read the Second Revision instead of this article, which is retained only as the record of the processes of my solving the mystery.

The crucial point in the development of Hideki Yukawa's meson theory came to him one night in October 1934. He writes in his autobiography Tabibito [1] as follows:

My new insight was the realization that this distance [the effective range of the nuclear force] and the mass of the new particle that I was seeking are inversely related to each other. Why had I not noticed that before?

This passage contradicts the fact that Yukawa used the above relation already in 1933. Namely, in April that year he made his first oral presentation at a meeting of an academic society. It was entitled "A consideration about the problem of electrons within nuclei," and the meeting was the one held in Sendai by Physico-Mathematical Society of Japan. The abstract of the presentation includes the following sentence [2]:

From the fact that the electron has the rest mass, we consider that the strength of the interaction decreases rapidly as the distance between the neutron and the proton becomes large compared with h/(2πmc).

In the work of the above presentation, Yukawa treated the possibility that the electron might be the mediator of the nuclear force between the neutron and the proton. This hypothesis included difficulties related to the spin and statistics of the electron. Therefore, Yukawa totally abandoned the hypothesis later together with the relation of the distance and the mass of the particle that would mediate the nuclear force [3]. Did this abandonment make it necessary for Yukawa to rediscover the relation? If so, this explains the contradictory remark of his "new insight."

We find another possible explanation of the contradictory description in the process of the making of Yukawa's autobiography. Hisao Sawano of the Assahi Shimbun Company helped the publication by editing Yukawa's manuscript [4]. If Sawano's editing had been to such an extent as to change Yukawa's original version into more dramatic one here and there, the passage that began with "My new insight" might have been Sawano's modification. To eliminate the expression different from the fact, Yukawa, perhaps, regularly checked the changes made by Sawano. However, Yukawa finished writing the last section related to the discovery of the meson theory just a few hours before his trip to Europe [5]. Thus, it is quite possible that Yukawa did not check Sawano's modification of that section.

Both Yukawa and Sawano are now in heaven. Thus, the mystery of the "new insight," i.e., which of the above two explanations was the case, does not seem to be solved easily. However, we have another clue to solve this problem.

In her autobiographical book* [6], Hideki Yukawa's wife, Sumi, wrote about the days of their visit to Stockholm for Hideki's receiving Nobel Prize. On arriving at a hotel there, they found that many journalists were waiting to interview Hideki. Sumi's passage about part of the interview is as follows:

One of the questions addressed to him was this: "We hear that the Japanese people study sitting on their legs in a straw-matted room. Did you, Dr. Yukawa, write your paper sitting on your legs or sitting on a chair at the Western-style desk?" Hideki thought a little while and said, "I did in neither of those ways. I put my thoughts together at night in bed." This is true. Hideki wrote the paper that brought him Nobel Prize after he had kept thinking many nights at the age of 27 in the year of Shōwa 9 [Note by the translator: 1934]. This story seems to have wrongly come across to Japan. Thus, in Japan they believe that the idea flashed to him in the middle of a night. [Translated by T.T. from Japanese.]

Here Sumi clearly denies the story in Ref. 1 of the "new insight" that came suddenly. Therefore, the second possibility given above, i.e., the contradiction is due to Sawano's modification, should be regarded as the case.

Hideki Yukawa's own autobiography was translated into English, French and German. Therefore, the wrong version of the story modified by Sawano has become famous world over. This is unfortunate. Sumi Yukawa's account quoted above should be informed widely.

(This article owes much to the discussion we have had at Osaka Science Museum among the members of "Citizens' Study Group on Hideki Yukawa.")

Note

* The title Kuraku-no-Sono was taken from the street name in Nishinomiya City, where Hideki and Sumi Yukawa lived in the years shortly after their marriage. It has the meaning of "the garden (sono) of joys and sorrows (kuraku)."

References

1. H. Yukawa, Tabibito (The Traveler), translated by L. Brown and R. Yoshida (World Scientific, 1982) p. 202.
2. H. Yukawa, Sūbutu-gakkaisi, Vol. 7, No. 2 (1933) quoted in Nihon-no Buturigaku-shi (History of Physics in Japan) (Tokai University Press, 1978) p. 319 (in Japanese; English translation of the quoted passage by the present author).
3. M. Kawabe and M. Konuma, Butsuri Vol. 37, p. 265 (1982) (in Japanese).
4. H. Yukawa, Atogaki (Afterwords) in Tabibito, (Kadokawa, 1960) (in Japanese).
5. H. Yukawa, Hon-no Naka-no Sekai (The World in Books) (Iwanami, 1963) p. 182 (in Japanese).
6. S. Yukawa, Kuraku-no-Sono (Kōdansha, Tokyo, 1976) pp. 349–350 (in Japanese).

The Solution to the Mystery of Yukawa's "New Insight"

Previously I wrote the article [1] that can be summarized as follows:

According to his autobiography [2], Yukawa arrived at a crucial point in the development of his meson theory one night in October 1934 by getting a "new insight." It was about the relation between the effective range of the nuclear force and the mass of the new particle he was seeking. However, this contradicts the fact that he used this relation already in 1933. There are two possibilities to explain the contradiction: (1) Yukawa once thoroughly abandoned the idea in which he used the relation, so that he had to rediscover it. (2) The description in Ref. 2 is the change made by Hisao Sawano of the Asahi Shimbun Company, who helped the publication of the autobiography by editing Yukawa's manuscript. Both Yukawa and Sawano passed, and the mystery of the "new insight," i.e., which of the above two explanations was the case, cannot be solved easily.

Reading the autobiographical book* [3] written by Hideki Yukawa's wife, Sumi, I have found a clue to solve the above mystery. Sumi wrote about the days of their visit to Stockholm for Hideki's receiving Nobel Prize. On arriving at a hotel there, they found that many journalists were waiting to interview Hideki. Sumi writes as follows:

One of the questions addressed to him was this: "We hear that the Japanese people study sitting on their legs in a straw-matted room. Did you, Dr. Yukawa, write your paper sitting on your legs or sitting on a chair at the Western-style desk?" Hideki thought a little while and said, "I did in neither of those ways. I put my thoughts together at night in bed." This is true. Hideki wrote the paper that brought him Nobel Prize after he had kept thinking many nights at the age of 27 in the year of Shōwa 9 [Note by T.T.; 1934]. This story seems to have wrongly come across to Japan. Thus, in Japan they believe that the idea flashed to him in the middle of a night. [Translated by T.T. from Japanese.]

This passage by Sumi clearly denies the story in Ref. 2 of the "new insight" that came suddenly. Therefore, the possibility (2) given above should be regarded as the case.

Hideki Yukawa's own autobiography was translated into English, French and German. Therefore, the wrong version of the story modified by Sawano, "The crucial point came to me one night in October. … My new insight was …" has become famous world over. This is unfortunate. Sumi Yukawa's account quoted above should be informed widely.

Note

* The title Kuraku-no-Sono was taken from the street name in Nishinomiya City, where Hideki and Sumi Yukawa lived in the years shortly after their marriage. It has the meaning of "the garden (sono) of joys and sorrows (kuraku)."

References

1. The Mystery of Yukawa's "New Insight," Ted's Coffeehouse (February 27, 2010).
2. H. Yukawa, Tabibito (The Traveler), translated by L. Brown and R. Yoshida (World Scientific, 1982) p. 202.
3. S. Yukawa, Kuraku-no-Sono (Kōdansha, Tokyo, 1976) in Japanese.

Feynman vs Rembrandt

The Novel-winning physicist Richard P. Feynman was born on May 11, 1918. In May, therefore, he is "the physicist of this month." The May-2010 issue of APS News [1] carries, on its first page, the sketch of a young lady under the title, "Who created this drawing?" The second and last sentence of its caption makes the reader go to page 5.

On page 5, we find a short article with a witty title, "Feynman drew more than diagrams," and a photo. The photo shows four more drawings and two persons, APS President Curtis Callan and his colleague Igor Klebanov. The article explains the followings: The drawing on page 1 was done in 1985 by celebrated Caltech physicist Richard Feynman and that it is one of several that are now at Princeton in the possession of Callan. The works were acquired in the mid-eighties by Princeton, where Feynman had been a graduate student, and were kept in the office of the late Sam Treiman, from whom Callan received them.

The bottom line of the article is as follows:

In the opinion of experts, Feynman was at least as good at drawing as Rembrandt was at physics.

This sentence seems to imply in a humorous manner that Feynman's drawings are pretty mediocre from the viewpoint of experts. To be sure about this, we have to see to what extent Rembrandt studied physics.

In the description of Wikipedia [2], we find that Rembrandt attended Latin school and was enrolled at the University of Leiden. However, he soon apprenticed to painters and then opened a studio at the age of 18 or so. Therefore, it might be safe to conclude that Rembrandt learned little about physics.

From cautiousness, I made Internet search by the combination of the words Rembrandt and physics; and found the article [3] entitled "The Rembrandt Solution" (the report does not include the word "physics," but one of comments on it does). It is about a technique developed by Rembrandt and other painters and called countershading. This technique creates the illusion of greater dynamic range of light intensities in their paintings than in real scenery. Illusion is the sensory distortion of the physical world. In order to utilize the effect of illusion, painters should know about the relationship between the nature of human senses and physical signals. Then, Rembrandt must have had sharp physical insight. Namely, Rembrandt's drawing technique makes us think that he was fairly adept at physics.

How can we argue about Feynman's goodness at drawing from his physics, conversely? Does his famous invention of Feynman diagrams prove the quality of his artistic skill? This seems to be difficult, though the invention at least indicates that his method of thinking was geometric as well as analytic. Is there any decent idea about this? I expect comments from readers.

1. APS News, Vol. 19, No. 5 (2010).
2. "Rembrandt," Wikipedia, the free encyclopedia (6 May 2010 at 00:13).
3. G. Randall, "The Rembrandt solution: What painting’s grand masters can teach today’s digital photographers" (2009).

On the Day I Shouted His Name ... (2)

Inoue wrote more than 60 dramas as well as many novels and essays. I have read none of them but have the book of collected photos, "Hisashi Inoue's Dalian*" [1], edited by Inoue and his theatrical troupe Komatsuza. Opening the book, I found Inoue's essay entitled "Dalian, the Dream Town." Reading this essay for the first time, I learned the relationship between Inoue and Dalian from it. I guessed that the photos in the book should have been part of collected data for a drama. However, the relationship had started much earlier. It was when one of his best friends moved to a primary school in Dalian and sent Inoue a picture card of Dalian in the winter of 1943. (I also moved to a primary school in Dalian in September 1944; namely, the friend of Inoue's and I had a similar experience. I bought this book to look at images of old Dalian dear to me.)

On the basis of his thought about Dalian, Inoue made a drama entitled "Enshō and Shinshō." Komatsuza made the first performance of this drama in 2005. It is about this story: Raconteurs Kokontei Shinshō and San'yutei Enshō went for performances in Manchuria** during the war time and were induced to stay in Dalian because of Japan's defeat. They had to do different and difficult jobs to live there for 600 days before coming back to Japan.

The last passage of Inoue's essay is as follows: 'The word "Dalian, the Dream Town" that entered deep in me as a child would not disappear until my death while its meaning is changing." One of the changes was due to his concern about Chinese people who had to live on the outskirts of Dalian when the city was part of Japan's borrowed land. Here we find Inoue's pacifism that made him one of initial members of the Article 9 Association.

Praying for his peaceful sleep in heaven, I wish to follow his footsteps in the efforts to keep Article 9*** of the Constitution of Japan and extend the renunciation of war all over the world.

Notes

* Dalian is a beautiful port city in the Northeast China. It was in the region of the land borrowed by Japan until August 1945, the time of Japan's defeated in the second World War.

** The historical name of the present Northeast China.

*** 1) Aspiring sincerely to an international peace based on justice and order, the Japanese people forever renounce war as a sovereign right of the nation and the threat or use of force as means of settling international disputes.

2) In order to accomplish the aim of the preceding paragraph, land, sea, and air forces, as well as other war potential, will never be maintained. The right of belligerency of the state will not be recognized.

Reference

1. H. Inoue and Komatsuza, ed., Hisashi Inoue's Dalian (Shōgakukan, 2002).