Monday, April 2, 2007

Galileo Galilei

A study of physics is made even more remarkable by studying the history of physics, and this man, Galileo Galilei, is often regarded as the father of modern physics.

In the initial phase of the development of human thought, science was considered indistinguishable from philosophy, which of course in itself is properly founded on logic. So people like Aristotle could say things like this:

All bodies move towards their natural place. For some objects, like cannonballs and human beings, the natural place for them is towards the Earth, and so they fall towards Earth. Other objects, like steam, belong to the celestial spheres, and so they rise up the heavens.

Of course, by modern standards of physics, this way of speaking is totally insane, simply because it is attributing a reason that seems to have no real logic. I could say:

Students in RI got into RI because they were born to be in RI.

Actually, the statement in itself is logical. It explains pretty much everything, but the thing we all take offence with is the fact that the statement isn't based on facts. The logic also works in reverse: if an object rises into the air, its natural place must be in the stars, not the other way round. We can't find an object that we know for sure belongs to the stars, and try to assess whether it rises into the air or not, because the very definition of belonging to the stars relies on the fact that it rises into the air naturally. There's no way to test such a statement.

And this attitude of needing facts to back up any statement that is made, making statements that can be falsified, making positive conclusions that allow us to make predictions (e.g. RI students get into RI because they have a high IQ: a statement that isn't necessarily true, but at least we can test it), all starts with Galileo.

Galileo was the first guy to realise the need for experimentation to back up any findings and any statements he may make. He reduced statements to mere hypotheses, that must be supported by experimental data: measurements taken from experiments.

And how do we associate measurements, numbers that we obtain by observing certain physical quantities such as height, mass, time, length etc. with these statements?

Mathematics, of course.

Galileo is famous for quipping "the language of God is mathematics". Not that he would know, since he was quickly branded a heretic by the Church. But the experiments that he designed, and the measurements that he took to prove the hypotheses that he made are no doubt brilliant.

In Galileo's time, heavy objects were thought to fall at a greater speed compared to lighter ones, as would seem "logical". But once again, logic without evidence was considered useless to Galileo. In a famous series of experiments on top of the Leaning Tower of Pisa, he dropped balls of different masses to seek evidence for the constant acceleration due to gravity. Indeed, from some of his work, he even managed to conclude that: In other words, the distance travelled by an object when dropped from rest is proportional to the time elapsed squared. This approach to science, which is so deeply in-grained in our psyche that today it is taken as a thing that is most natural, was most revolutionary. Today, we call this approach to science (of course, today much more advanced, but fundamentally still the same as the method of Galileo) the scientific method.

When astronauts first landed on the moon, one of the activities that they did was to drop a golden hammer together with a feather on the surface of the moon. Galileo, who could not have foreseen this happening nearly 400 years ago, would probably not have been surprised to see both the golden hammer and the feather hit the ground at the same time. This stands as testimony to the brilliance of mind of the man who many consider to be the first modern physicist.

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