Professor Hideki Yukawa's Anguish and a Lifelong Decision During a Three-Day Visit to Kochi to Unveil His First Bronze Statue: From a Cave Bat to the World

TL;DR

This paper explores Professor Hideki Yukawa's emotional and moral struggles during a 1954 visit to Kochi, Japan, highlighting his internal conflict over nuclear weapons and his pivotal decision regarding nuclear power advocacy.

Contribution

It provides a detailed historical analysis of Yukawa's personal anguish and decision-making process, based on original documents, during a critical period of nuclear proliferation.

Findings

Yukawa refused to speak about nuclear weapons during his visit.

He authored a pivotal essay on humanity and atomic power shortly after.

His mindset shifted dramatically within a single day.

Abstract

In 1954, following a five-year research period in the U.S., Professor Hideki Yukawa returned to Japan and visited Kochi on March 21 to attend the unveiling ceremony for the first statue of him ever built in Japan, a project initiated by the PTA of Yasu Elementary School in Yasu Town, Kochi Prefecture. By a coincidence of history, just three weeks prior on March 1, the U.S. had conducted a hydrogen bomb test at Bikini Atoll in the Pacific Ocean. Many Japanese fishing boats were operating there at the time and had not been informed in advance. As a result, numerous boats, including the Daigo Fukuryu Maru, were exposed to radiation. Upon his arrival at Kochi Station on the evening of March 21, Yukawa was relentlessly questioned by reporters about the Bikini hydrogen bomb. This was a source of deep anguish for Yukawa, a Japanese physicist who had won the Nobel Prize for his work on "atomic physics." He firmly refused to answer, stating that the topic was "outside the scope of my research." The next evening, at a public lecture in Kochi City on March 22, he again refused to speak about the Bikini hydrogen bomb or nuclear power, stating that he was an amateur in nuclear research and that there were many other experts. However, just four days later, on March 28, after returning to Kyoto, Yukawa drafted his famous essay, "The Turning Point for Humanity and Atomic Power," which was published in a newspaper on March 30. From that point on, he was drawn into the tumultuous issue of the Bikini hydrogen bomb and nuclear power. When did a tormented Yukawa make his decision? This article meticulously reveals, based on historical documents, what led the anguished Yukawa to make such a rapid decision within a single day and what caused the immense change in his mindset overnight.