Wednesday, December 8, 2010

Tycho Brahe and Kepler

  Tycho Brahe demonstrating a celestial globe to Emperor Rudolph II by Eduard Ender, 1855

“Now it is quite clear to me that there are no solid spheres in the heavens, and those that have been devised by the authors to save the appearances, exist only in the imagination.” - Tycho Brahe

Tycho Brahe and Johannes Kepler are two colorful characters who made crucial contributions to our understanding of the universe.

Tycho’s observations were accurate enough for Kepler to discover that the planets moved in elliptic orbits, and his other laws, which gave Newton the clues he needed to establish universal law of gravitation.

Tycho built vast instruments to set accurate sights on the stars, and used multiple clocks and timekeepers. 

He achieved his goal of measuring to one minute of arc. This was a tremendous feat before the invention of the telescope. His aim was to confirm his own picture of the universe, which was that the earth was at rest, the sun went around the earth and the planets all went around the sun - an intermediate picture between Ptolemy and Copernicus.

Tycho himself was not a Copernican, but proposed a system in which the Sun orbited the Earth while the other planets orbited the Sun. His system provided a safe position for astronomers who were dissatisfied with older models but were reluctant to accept the Earth's motion. It gained a considerable following after 1616 when Rome decided officially that the heliocentric model was contrary to both philosophy and Scripture, and could be discussed only as a computational convenience that had no connection to fact. Tycho's system also offered a major innovation: while both the geocentric model and the heliocentric model as set forth by Copernicus relied on the idea of transparent rotating crystalline spheres to carry the planets in their orbits, Tycho eliminated the spheres entirely. 

He was aware that a star observed near the horizon appears with a greater altitude than the real one, due to atmospheric refraction, and he worked out tables for the correction of this source of error.To perform the huge number of products needed to produce much of his astronomical data, Tycho relied heavily on the then-new technique of prosthaphaeresis, an algorithm for approximating products based on trigonometric identities that predated logarithms.

Johannes Kepler (1571-1630) believed in Copernicus’ theory. Having been raised in the Greek geometric tradition, he believed God must have had some geometric reason for placing the six planets at the particular distances from the sun that they occupied. He thought of their orbits as being on spheres, one inside the other. 

One day, he suddenly remembered that there were just five perfect Platonic solids, and this gave a reason for there being six planets - the orbit spheres were maybe just such that between two successive ones a perfect solid would just fit. He convinced himself that, given the uncertainties of observation at the time, this picture might be the right one. 

However, that was before Tycho’s results were used. Kepler realized that Tycho’s work could settle the question one way or the other, so he went to work with Tycho in 1600. Tycho died the next year. Kepler stole the data, and worked with it for nine years. 

The death of Tycho Brahe was more than suspicious and some people even consider that Brahe might have been murdered by Kepler. At the age of fifty four, Brahe was considered to be a very healthy person, but one day in October 1601, after attending a banquet, he suddenly fell ill and died within ten days of the event.

For a long time it was normally assumed that Brahe had died either from uremia, or from a burst bladder. But a forensic analysis of his hair that was conducted in the 1990s, shows an elevated amount of mercury in Brahe’s body short before his death. This discovery would rather confirm the old suspicion that Brahe was poisoned. There is a suspicion that Kepler poisoned Brahe. The two man had a very difficult relationship and Kepler was known for his unbecoming personality, but could Kepler really kill Brahe? But who wouldn't kill for knowledge and fame?

Brahe was not only a great astronomer, but like most scientists of his time, a great alchemist although he wasn't really trying to transmute base metals to gold, but rather develop medicines. Some of his potions contained mercury and it is a known fact that he took some of his preparations to cure minor discomforts. The amount of mercury in his medicines, however, was much too small to produce such a surprising forensic result. Brahe simply could not have overdosed.

The high amount of mercury in the analyzed hair sample actually suggested two separate poisonings: The first, that most probably occurred at the dinner party, where he had suddenly fallen ill. The second, the night before his death, when his condition had seemed to improve at first. A spike in his calcium level a few hours before his death also suggests that the poison was most certainly administered in a glass of milk.

Although Kepler makes a perfect suspect, there is no definite proof that he murdered Brahe. Brahe's death may forever remain a mystery although a new team of scientists under the leadership of Danish archeologist Prof. Jens Vellev certainly hopes to solve it with the help of the modern technology.

Article sources here, here & here  Also worth reading