Galileo Galilei
The great Italian astronomer and physicist Galileo inherited his interest in science from his musical father. Vincenzo Galilei specialised in the lute, a distant relative of modern guitars, and was also a musical theorist who used experimentation and mathematics to identify a new law that correctly described the relationship between the tension on a string and its musical pitch. Vincenzo’s discoveries helped to inspire his son’s mathematical approach to problems of ‘natural philosophy’ and foreshadowed Galileo’s own struggles to overturn outdated views of the world.
At age 17, Galileo became a student in the University at Pisa, training in medicine at his father’s suggestion. He made his first great discovery – that a pendulum has a regular period regardless of the width of its oscillations – while watching a swinging lamp in Pisa Cathedral, and had soon turned it into a practical device for measuring a patient’s pulse. After persuading his father to let him pursue his interest in mathematics, he became a professor by the age of 25.
Throughout his life, Galileo was perpetually short of cash. His father’s death left him responsible for his mother and three younger siblings – and later his own partner and three children. He boosted his income by taking in private students and selling his inventions, and later took a better paid job at Padua in the Republic of Venice. It was here in 1609 that he got word of an amazing new invention from the Netherlands – the telescope.
Galileo immediately set out to make a telescope of his own, using lenses mounted at either end of a card tube. Thanks to his talents for maths and experimentation, he soon found ways of improving on the basic idea. When he showed it to the Venetian rulers, they offered to double his salary and pay handsomely for the instrument itself.
Within a few months, the course of Galileo’s life was fatefully changed as he turned his telescope to the sky and made a series of discoveries including mountains on the Moon, countless faint stars and four small moons circling Jupiter. These findings undermined the traditional view that everything in the universe circled Earth – Nicolaus Copernicus, a Polish priest, had suggested the idea of a Suncentred universe in 1543, but until now there had been no observational evidence to back it up.
Galileo’s account of his discoveries in his book The Starry Messenger turned him into a scientific celebrity, but from 1613 onwards his arguments in support of the Copernican model put him on a collision course with the Roman Catholic Church. Powerful connections helped to protect him at first, but an argumentative nature got him into repeated trouble, and his 1632 Dialogue Concerning the Two Chief World Systems led to a trial before the inquisition and a sentence of house arrest for the rest of his life. Nevertheless, he continued to make important contributions to the foundations of modern physics right up until his death in 1642.