was a

theoretical physicist Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain, and predict natural phenomena. This is in contrast to experimental physics, which uses experi ...

. He studied various topics, such as the time reversal of quantum mechanics, pattern recognition,

cognitive science Cognitive science is the interdisciplinary, scientific study of the mind and its processes. It examines the nature, the tasks, and the functions of cognition (in a broad sense). Mental faculties of concern to cognitive scientists include percep ...

, and the concept of time. He was the first physicist who claimed that quantum

probability theory Probability theory or probability calculus is the branch of mathematics concerned with probability. Although there are several different probability interpretations, probability theory treats the concept in a rigorous mathematical manner by expre ...

is time-asymmetric (irreversible; non-invariant under time reversal), and reject the conventional analysis of the time reversal of probability laws. He developed the Double Inferential Vector Formalism (DIVF), later known as the

Two-state vector formalism The two-state vector formalism (TSVF) is a description of quantum mechanics in terms of a causal relation in which the present is caused by quantum states of the past and of the future taken in combination. Theory The two-state vector formalism is ...

( TSVF), which is sometimes interpreted as contradicting his claim of time-asymmetry, but this is a misunderstanding. He also proposed the

Ugly duckling theorem The ugly duckling theorem is an argument showing that classification is not really possible without some sort of bias. More particularly, it assumes finitely many properties combinable by logical connectives, and finitely many objects; it asserts ...

Early life and education

Satosi Watanabe was born on May 26, 1910, in

Tokyo Tokyo, officially the Tokyo Metropolis, is the capital of Japan, capital and List of cities in Japan, most populous city in Japan. With a population of over 14 million in the city proper in 2023, it is List of largest cities, one of the most ...

. He attended Gakushuuin Middle High School and Tokyo High School. In 1933, he graduated from

Tokyo Imperial University The University of Tokyo (, abbreviated as in Japanese and UTokyo in English) is a public university, public research university in Bunkyō, Tokyo, Japan. Founded in 1877 as the nation's first modern university by the merger of several Edo peri ...

in theoretical physics, where Torahiko Terada was his teacher. The imperial government sent him to France to study.

Louis de Broglie Louis Victor Pierre Raymond, 7th Duc de Broglie (15 August 1892 – 19 March 1987) was a French theoretical physicist and aristocrat known for his contributions to quantum theory. In his 1924 PhD thesis, he postulated the wave nature of elec ...

encouraged Watanabe to study

thermodynamics Thermodynamics is a branch of physics that deals with heat, Work (thermodynamics), work, and temperature, and their relation to energy, entropy, and the physical properties of matter and radiation. The behavior of these quantities is governed b ...

and

wave mechanics Wave mechanics may refer to: * the mechanics of waves * the application of the quantum wave equation, especially in position and momentum spaces * the resonant interaction of three or more waves, which includes the "three-wave equation" See al ...

. In 1937, he moved to

Leipzig Leipzig (, ; ; Upper Saxon: ; ) is the most populous city in the States of Germany, German state of Saxony. The city has a population of 628,718 inhabitants as of 2023. It is the List of cities in Germany by population, eighth-largest city in Ge ...

and started to study nuclear theory under

Heisenberg Werner Karl Heisenberg (; ; 5 December 1901 – 1 February 1976) was a German theoretical physicist, one of the main pioneers of the theory of quantum mechanics and a principal scientist in the German nuclear program during World War II. He pub ...

. In the same year, Watanabe married Dorothea Dauer, a scholar of German literature. In 1939, at the beginning of

World War II World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

, he left Germany and stayed with

Niels Bohr Niels Henrik David Bohr (, ; ; 7 October 1885 – 18 November 1962) was a Danish theoretical physicist who made foundational contributions to understanding atomic structure and old quantum theory, quantum theory, for which he received the No ...

for a time. In December, he returned to Japan with his family.

Career

In Japan, he worked at the Physical and Chemical Research Institute (''Rikagaku Kenkyujo'') at Tokyo Imperial University as an assistant professor, and as a physics professor at

Rikkyo University , also known as Saint Paul's University, is a private university, in Ikebukuro, Tokyo, Japan. Rikkyo is one of the five MARCH (Japanese universities), MARCH universities, the group of private universities in the Kantō region, Kanto region, toge ...

. In 1950, he left for the United States. His argument that quantum mechanics is time-asymmetric (irreversible; non-invariant under the time reversal transformation) is repeated in a number of his papers (1955; 1965; 1966; 1972). This result means that physicists have used the wrong transformation of probability laws to represent time reversal, and the claims that quantum mechanics is time reversal invariant are invalid. Watanabe's argument has not been accepted by physicists or philosophers however. The assumption that quantum mechanics is time symmetric on the basis of conventional proofs is almost universal in the literature on time in physics to this day. He developed the Double Inferential Vector Formalism (DIVF), later known as the

( TSVF). The DSVF/TSVF is often interpreted as a time-symmetric interpretation of quantum mechanics (see Minority interpretations of quantum mechanics). However Watanabe considered that the normal physical theory of quantum mechanics that holds for real physics is time-asymmetric. He consequently rejected the conventional view that physical time asymmetry is only explained by asymmetric boundary conditions on the universe, and claimed it is a law-like feature of quantum physics. Time-symmetric interpretations of quantum mechanics were first suggested by

Walter Schottky Walter Hans Schottky ( ; ; 23 July 1886 – 4 March 1976) was a German solid-state physicist who played a major early role in developing the theory of electron and ion emission phenomena, invented the screen-grid vacuum tube in 1915 while wor ...

in 1921, and later by several other scientists. Watanabe proposed that information given by forwards evolving

quantum state In quantum physics, a quantum state is a mathematical entity that embodies the knowledge of a quantum system. Quantum mechanics specifies the construction, evolution, and measurement of a quantum state. The result is a prediction for the system ...

s is not complete; rather, both forwards and backwards evolving quantum states are required to describe a quantum state: a first state vector that evolves from the initial conditions towards the future, and a second state vector that evolves backwards in time from future boundary conditions. Past and future measurements, taken together, provide complete information about a quantum system. Watanabe's work was later rediscovered by

Yakir Aharonov Yakir Aharonov (; born August 28, 1932) is an Israeli physicist specializing in quantum physics. He has been a Professor of Theoretical Physics and the James J. Farley Professor of Natural Philosophy at Chapman University in California since ...

Peter Bergmann Peter Gabriel Bergmann (24 March 1915 – 19 October 2002) was a German-American physicist best known for his work with Albert Einstein on a unified field theory encompassing all physical interactions. He also introduced primary and seconda ...

and

Joel Lebowitz Joel Louis Lebowitz (born May 10, 1930) is a mathematical physicist known for his contributions to statistical physics, statistical mechanics, and many other fields of mathematics and physics. He is a founding editor of the Journal of Statis ...

in 1964, who later renamed it the

( TSVF).Yakir Aharonov, Lev Vaidman: ''Protective measurements of two-state vectors'', in: Robert Sonné Cohen, Michael Horne, John J. Stachel (eds.): ''Potentiality, Entanglement and Passion-At-A-Distance'', Quantum Mechanical Studies for A. M. Shimony, Volume Two, 1997, , pp. 1–8
p. 2
/ref> In 1956, he became a researcher at the IBM Watson Laboratory and started to build his own information theory based on quantum mechanics. He taught at Yale University and the

University of Hawaii A university () is an educational institution, institution of tertiary education and research which awards academic degrees in several Discipline (academia), academic disciplines. ''University'' is derived from the Latin phrase , which roughly ...

, became chairman of the International Time Academy, and was the Vice President of International Philosophy Academy. On October 15, 1993, he died in Tokyo.

Family

His father, Chifuyu Watanabe, was a Minister of Justice at Second Wakatsuki Cabinet. His elder brother, Takeshi Watanabe, was Vice Minister of Finance for International Affairs and director general of Asia Development Bank. His wife, Dorothea Dauer Watanabe, was a professor of German (language and literature) at the University of Hawaii. His son, Hajime Watanabe, is a professor of philosophy at the

University of California, Santa Barbara The University of California, Santa Barbara (UC Santa Barbara or UCSB) is a Public university, public Land-grant university, land-grant research university in Santa Barbara County, California, United States. Tracing its roots back to 1891 as an ...

References

Bibliography

* ''Le deuxième théorème de la thermodynamique et la mécanique ondulatoire'', Paris : Herman et Cie, 1935 * ''Knowing and guessing : a quantitative study of inference and information'', New York : John Wiley & Sons, 1969 * ''Pattern recognition : human and mechanical'', New York : John Wiley & Sons, 1985

External links

Publication list
at

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