Thursday, March 04, 2010

"Kwontamu" or "Kwantamu" for Quantum

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In written Japanese language, the words borrowed from foreign languages are expressed by one of two types of phonetic characters called katakana. For the word "quantum," we have a proper Japanese word "ryōshi." Therefore, it is quite rare to see katakana expression for "quantum."

In reading books written in English, however, I had kept the habit of reading "quantum" in my mind by the pronunciation close to the katakana expression "クォンタム (kwontamu)." One or two years ago, I found a different katakana expression, "クァンタム (kwantamu)," in an essay by Sin-itiro Tomonaga. Because Tomonaga was a Nobel-winning physicist, I thought that his expression should be accepted and became to pronounce "quantum" like "kwantamu."

In the morning of Sunday, February 21, I saw the katakana expression "kwontamu" in the title of a new novel reviewed in the Asahi Shimbun. The full title of the book was "クォンタム・ファミリーズ (Kwontamu Famirīzu)" [1] meaning "Quantum Families." Then I wondered which expression is closer to the pronunciation of "quantum," "kwontamu" or "kwantamu." I looked up a dictionary and learned belatedly that "kwontamu" is closer to British pronunciation, and "kwantamu" to American pronunciation. Thus, we should consider both the expressions to be valid. Tomonaga's studies abroad were at Leipzig and Princeton, making it reasonable for him to use "kwantamu."

  1. Hiroki Azuma, Kwontamu Famirīzu (Shinchōsha, 2009). The author uses the parallel world hypothesis in modern physics to depict the mixture of plural stories.


  1. How do you write the mathematics in Japanese? Are you using the same Latin and Greek letters that we do or Japanese symbols? What would the Dirac equation look like in a Japanese physics book?

  2. It is an interesting question. In the present day Japan, we use the same expression in the math as in Europe and USA. Chinese characters for numbers, 一, 二, 三, 四, 五, …, corresponding to 1, 2, 3, 4, 5, …, were used for the math until about 1870, when the new education system learned from Europe started; and, even today, those characters are used sometimes in the sentences written in Japanese. However, we, most of the present Japanese people, do not know what arithmetic symbols they used before that year. Thus, we have no expression peculiar to modern Japanese math or physics books.