Galileo Galilei

b. 15 February 1564
d. 8 January 1642

Noteworthies:

• Invented physics

Galileo is one of those people to whom people attribute lots of things just because he was great. In much the same way that Washington did not throw a silver dollar across the Potomac (it being more than a mile across at Mount Vernon) any more than he chopped down a cherry tree on his father's estate, Galileo is largely innocent of all of the one-liner attributions that he is awarded. For instance, he did not invent the telescope (although he was the first to turn it skyward). Equally, he never performed an experiment during which he dropped weights off the Tower in Pisa, thus proving that all masses fall at the same rate. Not surprisingly, he did not really invent physics either. But I'll show you what I meant by that.

Galileo was a student of observation. On top of that, he was sarcastic, confrontational, pugnacious, and brilliant. His mantra was the quest of observable truth and the rejection of "truth" declared in ignorance. His mission was to enlighten those ignorant who trusted their source of truth.

During his time, truth was whatever the Church declared it to be. The Earth was the center of the universe, all things in the heavens were perfectly spherical and traveled in perfect circles, and all unanswerable questions were answered by Church leaders. Galileo's life seems to have been dedicated to breaking the mindset that truth is what men of power think it should be. His methodology was flawless: experimentation and demonstration.

When told (by a Cardinal) that ice floats only because of its sheet-like shape, Galileo performed a public experiment in which he demonstrated that density rules buoyancy. The audience watched as thin sheets of ebony sunk while large blocks of ice remained at the surface. No one could refute the evidence before them.

He was challenged on basically every important discovery he made. When observing the moon through a telescope, he discovered mountains, ridges, and hills. Saturn had "ears" and the Sun had spots. All of these went against the common philosophy that the sky was filled with perfectly circular, perfectly formed bodies. His discoveries were uniformly pronounced untrue until he simply showed his accusers what he had seen with his own eyes.

Again, turning heavenward, Galileo discovered that Venus—like the Moon—displayed phases: crescent, half, full, and back to new. Such a thing could only be possible if it orbited the sun, sometimes lying between us and the Sun, and sometimes being on the other side of the Sun. The Church was scared and frustrated. If a layman could disprove "truths" that had been taught for years by the Church, their authority would be undermined. They arrested him, threatened him with his life, and eventually exiled him. But the damage was done. People started to see that physical truths needed to be observable. Simply declaring a geocentric universe could not make it true. Our declarations must be backed by confirmed fact.

Lest we erroneously think that Galileo's anti-Church stance was anti-religious, let us consider the counsel he gave to his accusers who argued their points from out-of-context Biblical references: "The task of wise interpreters is to find true meanings of scriptural passages that will agree with the evidence of sensory experience." Indeed, his stance was more religious than their own. He maintained that God created a physically explainable world and that part of our reason for being on it was to figure out how it worked. We do not have to deny that God held the Sun in the sky for Joshua, or that He parted the Red Sea just because we can't explain it. But we also do not have to assume that it will remain unexplainable forever.

From his example comes the scientific method. A scientific question asked can only be considered answered when it is backed by repeatable, concrete evidence. The answered question then remains to be further backed by experiment or else disproved by more detailed analysis. The quest is not to be personally right, but to find the truth behind the phenomena that we encounter each day.

Perhaps these stories of Galileo disproving the clergy by experimentation seem trivial. Surely they would have thought to test buoyancy by putting things in water. Isn't that the obvious solution? That sentiment, in and of itself, is a tribute to the great gift that Galileo gave us. We see the simplicity in his methods because we have adopted them through and through. You were raised to experiment, to test, to try, to guess and be wrong, and to reason in part because of the scientific contributions made by an Italian astronomer (of course) several hundred years ago. Someone else probably would have done it if he hadn't been so persistent, but his influence stands out as the catalyst for a reasoning, scientific community that seeks for physical truth by physical confirmation.