Graziano & Raulin
Research Methods (9th edition)
Galileo Galilei (1564-1643) was an Italian mathematician, astronomer, and physicist.
Galileo is considered by many to be the first systematic physical scientist, because he studied nature through empirical observation, experimentation, mathematics, and inductive reasoning. He integrated and applied the procedures that had been developed in a long line of thinkers, from Thales to Roger Bacon.
Galileo made discoveries concerning the law of the pendulum (i.e., its isochronism--that the oscillation time is the same regardless of the amplitude of the swing). He also invented the hydrostatic balance to measure specific gravity, wrote on the mathematics of specific gravity, and demonstrated that bodies of differing weights fall at the same velocity. His discoveries were at variance with established knowledge, and this caused problems throughout his professional life.
At the age of 45, Galileo learned of the invention of the telescope, constructed one for himself, and began a series of celestial observations. Using his telescope, he discovered the mountainous terrain of the moon, the phases of the planet Venus, the satellites of Jupiter, and the fact that the moon “shines” by reflected sunlight.
Galileo may be best known for the problems he had with the Catholic Church over his heretical acceptance of the Copernican heliocentric theory of the solar system. Copernicus had published his heliocentric model of the solar system about 20 years before Galileo’s birth. Galileo accepted the Copernican model, especially since his own calculations supported it. The Catholic Church, however, maintained that Ptolemy’s geocentric model was the truth, because it was in accordance with scriptures. When Galileo published his own strong supporting evidence in 1630 for the Copernican model, his work was condemned, sale of his book was forbidden, and he was forced by the inquisition to recant his work. He lived another eight years, during which he completed his book on mechanics and made additional discoveries with the telescope.