September 24

Are You Sure ...

Author, peace activist, and alleged time-traveller John Brunner famously used a bespoke Lee and Turner color projector, which he had customized for use as a scrying engine.

• ... that polymath Johann Heinrich Lambert demonstrated that illumination is proportional to the strength of the light source, and inversely proportional to the square of the distance of the illuminated surface and the sine of the angle of inclination of the light's direction to that of the surface?

• ... that mathematician Lev Schnirelmann used the Brun sieve to prove that any natural number greater than 1 can be written as the sum of not more than C prime numbers, where C is an effectively computable constant?

• ... that journalist and author George Plimpton is famous for his "participatory journalism", which included competing in professional sporting events, acting in a Western, performing a comedy act at Caesars Palace in Las Vegas, and playing with the New York Philharmonic Orchestra and then recording the experience from the point of view of an amateur?

On This Day in History and Fiction

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  1054: Composer, mathematician, and astronomer Hermann of Reichenau dies. He wrote a treatise on the science of music, several works on geometry and arithmetic, and astronomical treatises (including instructions for the construction of an astrolabe, at the time a very novel device in Western Europe).

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  1501: Gerolamo Cardano born. He will be one of the most influential mathematicians of the Renaissance.

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  1625: Mathematician and politician Johan de Witt born. He will derive the basic properties of quadratic forms, an important step in the field of linear algebra.

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  1844: Mathematician Max Noether born. Noether will contribute to algebraic geometry and the theory of algebraic functions. He will be the father of mathematician Emmy Noether.

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  1888: Cryptographer and intelligence officer Edward Travis born. Travis will become the operational head of Bletchley Park during World War II, and later become the head of GCHQ.

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  1934: Writer and peace activist John Brunner born.

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  1938: Mathematician Lev Schnirelmann dies. He proved that any natural number greater than 1 can be written as the sum of not more than C prime numbers, where C is an effectively computable constant.

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  1991: Children's author, political cartoonist, illustrator, poet, animator, screenwriter, and filmmaker Theodor Seuss "Ted" Geisel dies. Geisel wrote and illustrated more than 60 books under the pen name Dr. Seuss, including many of the most popular children's books of all time, selling over 600 million copies and being translated into more than 20 languages.