The Epic Interactive Encyclopedia 1997/The_Epic_Interactive_Encyclopedia_97.iso/g/galileo/infotext

Text File | 1992-09-03 | 2KB | 46 lines

Unit (symbol gal) of acceleration, used in
geological surveying. One galileo is 10^-2
metres per second per second. The Earth's
gravitational field often differs by several
milligals (thousandths of gals) in different
places, because of the varying densities of
the rocks beneath the surface.

Galileo
properly Galileo Galilei, 1564-1642. Italian
mathematician, astronomer, and physicist. He
developed the astronomical telescope and was
the first to see sunspots, the four main
satellites of Jupiter, mountains and craters
on the Moon, and the appearance of Venus
going through `phases', thus proving it was
orbiting the Sun. In mechanics, Galileo
discovered that freely falling bodies, heavy
or light, had the same, constant acceleration
(although the story of his dropping
cannonballs from the Leaning Tower of Pisa is
questionable) and that a body moving on a
perfectly smooth horizontal surface would
neither speed up nor slow down. He discovered
in 1583 that each oscillation of a pendulum
takes the same amount of time despite the
difference in amplitude. He invented a
hydrostatic balance, and discovered that the
path of a projectile is a parabola. Galileo
was born in Pisa, and in 1589 became
professor of mathematics at the university
there; in 1592 he became a professor at
Padua, and in 1610 was appointed chief
mathematician to the Grand Duke of Tuscany,
Florence. Galileo's observations and
arguments were an unwelcome refutation of the
ideas of Aristotle taught at the (Church-run)
universities, largely because they made
plausible for the first time the heliocentric
(Sun-centred) theory of Copernicus. Galileo's
persuasive Dialogues on the Two Chief Systems
of the World 1632 was banned by the Church
authorities at Rome; he was made to recant by
the Inquisition and put under house arrest
for his last years.