Italian philosopher,
astronomer, scientist and mathematician, Galileo Galilei (1564 – 1642) is
probably best remembered for his work in support of Copernicus’ heliocentric theory of the solar system. For the sake
of his life, Galileo recanted his views in 1633, admitting that the earth did
not spin on its own axis. It is unlikely that the recantation was sincere and
he nevertheless remained under house arrest.
In 1608 the Dutchmen
Lippershey invented the telescope. Within two years Galileo used it to dramatic
effect, showing by his astronomical observations that the Ptolemaic or
geocentric theory which held that the Earth was at the centre of the universe,
was seriously flawed. Galileo also observed that the Milky Way was in fact made
up of many millions of individual stars. He observed the phrases of Venus and
discovered the moons of Jupiter, which had theological experts up in arms.
Indeed, Galileo’s findings attracted such sharp criticism, both from secular
and ecclesiastical quarters that he felt compelled to offer, both in his
defence and in reply to his critics, the Letter
to the Grand Duchess Christina in 1615. In the Letter, Galileo argues that scientific
and theological matters should not be confused. Science could not cast doubt on
religious doctrine, only strengthen it. Nonetheless he was condemned by the
Inquisition, first in private communication in 1616 and later in 1633, when he
publicly recanted.
Although his work was
instrumental in bringing the Copernican system into prominence, Galileo was far
more than just an astronomer. Much of his important work lay in dynamics and
the principles of movement. He was the first to discover the law of falling bodies, or constant
acceleration, published after his recantation and whilst still under house
arrest in 1638, in his Discourse on Two
New Sciences.
Moreover, what would later
be Newton’s celebrated first Law of Motion was directly taken from Galileo’s principle of inertia, namely
that a body moves in a straight line with uniform velocity unless acted upon.
This principle was
important in helping to support the Copernican theory. Critics of Copernicus
had claimed that if the heliocentric theory were true, then a falling body
should not fall in a straight line, but in fact land somewhat to the west of
the point from which it was dropped, on account of the eastwise rotation of the
Earth. It had been proven by experiment that this was not the case, a result
which led many to dismiss Copernicus as wrong even if they did not share the
religious reasons for dismissing him. It took Galileo’s work in dynamics to
show why the prediction was not fulfilled. Simply put, the falling stone
retains the rotational velocity of the Earth.
Philosophically, Galileo held
that “the book of nature is written in
the language of mathematics.” He was heavily influenced by Greek philosophy
and a great admirer of Archimedes. He also maintained, like John Locke, that
there was a metaphysical distinction between the primary and secondary
qualities of bodies. The former are essential and inherent in objects, whereas
the latter exist only insofar as they cause certain effects in the minds of
observers. Undoubtedly, Galileo was a great thinker who risked much in the
pursuit of truth, helping to set free the quest for knowledge from the chains
of religious dogmatism.
[Summarized from Philosophy 100 Essential Thinkers by
Philip Stokes, 2012]
Lord, Give
Us Today Our Daily Idea(s)
