Brahmagupta
598-665?
Indian Astronomer and Mathematician
Brahmagupta, a Hindu astronomer and mathematician, is best known for work performed while head of the Ujjain astronomical observatory, one of the leading centers for astronomical and mathematical research in ancient India. While there, he developed a number of important mathematical concepts, investigated the motions of planets and other celestial bodies, and arrived at a fairly accurate estimate of the length of the terrestrial year. His most important contributions are the introduction of the number zero to mathematics and his masterpiece, Brahma Sphuta Siddhanta (The opening of the universe), in which many of his mathematical and astronomical discoveries were set out in verse form.
Brahmagupta was likely born in northwestern India, and spent the majority of his life in what is now the city of Bhinmal, in the Indian state of Rajasthan. Little else is known of his early life.
By the age of 30, Brahmagupta had completed a near total revision of an old work of astronomy, the Brahma Siddhanta. In this work, he devoted several chapters to mathematics, including the first mathematical treatment of the number zero and the mathematical rules surrounding its use. Brahmagupta also included over four chapters on pure mathematics and several additional chapters on applied mathematics. Among the topics he addressed (many of which were new to science) were methods for solving quadratic equations, arithmetic progressions, and mathematical methods for approaching astronomical problems.
This last topic may be Brahmagupta's most significant contribution to science, because he was the first person to consider using mathematical (particularly algebraic) techniques to predict astronomical phenomena such as planetary motions, solar and lunar eclipses, and so forth. In particular, he was able to describe the manner inwhich the rising and setting of the planets could be calculated well in advance, as well as their predicted positions in the sky. Seemingly simple today, this was a major advance at that time, and involved many laborious calculations.
Brahmagupta was also involved in the debate over the shape of Earth and the universe. He disagreed with the school of thought that asserted that Earth was flat or concave (like the inside of a bowl). Instead, he thought it most likely that both Earth and the universe were round. However, he also felt certain that Earth was stationary in the universe, a view that is now known to be incorrect.
One of Brahmagupta's later accomplishments was calculating the length of the solar year. In early work, he determined this to be 365 days, 6 hours, 5 minutes, and 19 seconds. This figure was later revised to 365 days, 6 hours, 12 minutes, and 36 seconds. However, some suspect this latter value to have been taken from the work of Aryabhata (476-550?), from which Brahmagupta's value differs by only a few seconds. In any event, both values are very close to today's accepted value of about 365 days, 5 hours, 48 minutes, and represent a remarkably accurate calculation based on information obtained by very primitive instruments.
Perhaps the greatest tribute to Brahmagupta's mathematical talents is that his book was used to introduce the basic ideas of algebra to Islamic mathematicians, who were later given credit for its invention. His work was expanded upon to form the basis of what is now taught in schools, and the Islamic mathematicians must be given credit for adding their original contributions to Brahmagupta's work, but their credit must also be shared with him.
Brahmagupta died between 660 and 670. At the time of his death he was widely acknowledged as the greatest mathematician of this period of Indian history, and one of the greatest Indian mathematicians of any time. This is reflected in one of his honorary titles, "Ganita Chakra Chudamani," bestowed by a fellow scientist and translated as "the gem of the circle of mathematicians."
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