Galileo's Logic

I wrote “Galileo’s Logic” when I was invited to perform at a national physics conference. 

I love being the entertainment at conferences, and I’ve done them on subjects from Shakespeare to defense to spirituality to sustainable agriculture. Whenever I perform at a conference, I try to write a song inspired by the topic of the conference. There was no way I could think of to write about physics directly, but all physicists admire Galileo, and his story is one I taught for ten years at the University of California, Santa Cruz, in a course called “Cosmology and Culture.”

Now I’m going to tell you more than anyone probably needs to know to listen to a song, but I find the story not only fascinating but relevant to a huge misunderstanding that has political repercussions in America today — which is, that science and religion are by nature in conflict.

Iin Galileo’s time the doctrine of the Catholic Church was the Greek/medieval view that Earth was the center of the universe, and the sun, moon, planets, and stars all went around us every day.  This mattered because for centuries the hierarchy of the Church had been based on this supposed hierarchy of the heavens. But Galileo’s early telescopic observations proved that Earth could not be the center. He tried to get the Pope to just look through the telescope, since the evidence was clear, but the Pope refused and forced Galileo under threat of torture to publicly retract this “heresy.” 

Without a telescope Venus is just a fuzzy spot of light, always the same brightness. Galileo had predicted that if it could ever be seen whether Venus had phases or not, that would prove whether the sun or Earth is the center.  Sure enough, with the telescope this is what Galileo saw:

The only way to explain this is that Venus orbits the sun inside the orbit of Earth. When Venus passes between Earth and the Sun, it looks big because it’s close, but we only see a crescent, because the lit side is facing away from us.  But when Venus is on the far side of the sun from Earth, it looks much smaller, but we see its whole face lit up. 

The thing is, it’s always the same brightness, no matter the phase!  You can see why by imagining the little full circle smeared out over the thin crescent.

 A few years ago when the Wilma Theater in Philadelphia mounted Brecht’s play “Galileo”, my astrophysicist husband and I, on a book tour for our first book, were invited to be on a panel onstage as part of a post-performance discussion with the audience.  I was astounded by the number of people in the audience who judged Galileo a coward for retracting his theory when he knew it was true.  They felt he should have stood up for himself and accepted torture!

This song is my answer to those people.  It’s my attempt to unpack Galileo’s famous but cryptic phrase – “It still moves” (Eppure si muove) –  which (legend goes) he whispered to his student as he was being led away after the trial into house arrest.  

What would Galileo have said if he’d had the freedom to do so? 

He understood 400 years ago what so many people still do not understand today: 

The real conflict is not between religion and science but between dogma and truth.

Galileo’s Logic

Words and music © 2023 Nancy Ellen Abrams

It doesn’t matter what the heretics say. Listen to the Church

Earth is unmoving till the end of days. Listen to the Church

                  Earth is the center of the heavenly spheres

In the Great Chain of Being, God placed us here

It doesn’t matter what the heretics say. Listen to the Church

He heard of an invention and full of hope

Galileo ground lenses for a telescope

He trained it on Venus and there he saw

The proof that he’d been waiting for

Venus had phases, so it circled the sun

Earth was not the center; the whole cosmos was undone

They led him to the dungeon.  The Pope showed him the rack

“It’s this,” he said, “or take your theory back”

Galileo looked in horror and began to shake

“You’re right,” he said, “I’m wrong.  My theory was a mistake”

“Master,” cried his student, “How can you now give in?

No one will believe us if you let them win!”

It doesn’t matter what the Church may say. Earth still moves

Over men they may get their way. Earth still moves

It doesn’t matter what we say or do

Earth isn’t listening to them, me, or you

It doesn’t matter what the Church may say. Earth still moves

He whispered to the student, “Yes, I did pretend remorse

Earth doesn’t need my pain to keep it on course

It will sail on forever.  Let the Pope cry heresy

But this is how God made the Earth, so God agrees with me

It doesn’t matter what the Church may say.  Earth still moves

They could torture me night and day.  Earth still moves

Why be a martyr to look more pure?

That can’t make truth any truer

It doesn’t matter what the Church may say.  Listen to the Earth