Moon Man Galileo

Adam Gopnik writes a long Galileo article in the New Yorker magazine:

But, when you’ve read through his collected evidence, the myth seems pretty much right: Galileo wrote a book about the world saying that the earth goes around the sun, and the Church threatened to have him tortured or killed if he didn’t stop saying it, so he stopped saying it. Mayer believes that had Galileo been less pugnacious things would have worked out better for science; yet his argument is basically one of those “If you put it in context, threatening people with hideous torture in order to get them to shut up about their ideas was just one of the ways they did things then” efforts, much loved by contemporary historians.

To be sure, Galileo’s trial was a bureaucratic muddle, with crossing lines of responsibility, and it left fruitfully unsettled the question of whether Copernican ideas had been declared heretical or if Galileo had simply been condemned as an individual for continuing to promote them after he had promised not to. But what is certain is that, in 1633, Galileo was threatened with torture, forced on his knees to abjure his beliefs and his book, and then kept under house arrest and close watch for the rest of his life. (Albeit of a fairly loose kind: John Milton came to see him, and the image of the imprisoned scientist appears in Milton’s defense of free speech, the “Areopagitica.”)

This gives the impression that Galileo was going to be tortured for telling a scientific truth. No such thing was ever considered.

The threat of torture was only part of the oath to tell the truth. Any witness at any trial could be said to have been under such a threat.

Furthermore, Galileo was not restricted from announcing and publishing scientific observations, facts, and theories. What he did was to publish a book arguing the entirely false notion that the daily tides prove the motion of the Earth. The Church officials explained to him why he was wrong, and warned him not to publish it.

For the last century, the favored understanding is that motion is relative to a frame of reference. It is nonsense to say that the Earth moves, unless you also supply a reference frame. And Galileo's theory of tides was wrong, contrary to what was established knowledge for millennia.