Galileo, the Telescope & the Church

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  • 0:06 The Copernicus Crisis
  • 1:49 Galileo's Falling…
  • 3:21 The Importance of the…
  • 4:49 Telescope and Starry Messenger
  • 7:21 The Church's Response
  • 9:25 Lesson Summary
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Lesson Transcript
Instructor: Max Pfingsten
This lesson explores the contributions of Galileo to modern science. It examines his early steps toward a scientific method, his work on falling bodies and, of course, his astronomical discoveries. Finally, the Church's reaction to these discoveries is explored.

The Copernicus Crisis

Others who believed in heliocentrism could not be pressured by the Catholic Church.
Heliocentrism Religions

At the dawn of the 17th century, the Roman Catholic Church was in crisis. The Protestant Reformation was sweeping across Europe. The Catholic Church was losing entire countries to this heresy. And now it seemed like the universe itself was falling apart.

The Church had spent centuries believing that the earth was at the center of the universe. The sun, moon, planets and stars orbited the earth embedded in concentric spheres, each one larger than the last, like a celestial Russian doll. Then, in 1543, this fellow Copernicus came up with the wild notion that the sun, not the earth, was at the center of the universe, a concept that came to be known as heliocentrism.

The Church tried to stomp this idea out in any way they could. Yet despite their best efforts, heliocentrism was becoming ever more popular. Fools like Johannes Kepler or Tycho Brahe were even expanding upon it. And the Church could do nothing to stop them! Gone were the good old days when the Church could burn people alive for saying things they disagreed with. As a Protestant living in a Protestant country, Kepler and his ilk were forever out of the Church's reach.

Unable to silence these mad theories, the Church's only comfort was that no one could actually prove them. Unfortunately for the Church, a fellow named Galileo just happened to be in the business of proving things. Unfortunately for Galileo, unlike his fellow scientists safe in the Protestant North, Galileo lived right under the nose of the Pope himself.

Galileo's Falling Bodies Experiment

Galileo conducted experiments to prove his theories were accurate.
Galileo Falling Bodies Experiment

Now what do I mean when I say that Galileo was in the business of proving things? Well, let me give you an example. Imagine you're holding a feather in one hand and an apple in another. You let them both go. Which one will hit the ground first? The apple, of course.

From this you might draw the conclusion that heavy things, like the apple, fall faster than light things, like the feather. This was how most people, with the exception of a few philosophers, thought gravity worked for thousands of years.

Galileo rejected this common-sense notion. 'Our observation of the feather and apple cannot be counted as proof,' he would say, 'because there are too many factors involved. The feather isn't just lighter than the apple, it also has a different shape. If we want to see how something's weight affects how fast it falls, we need to remove all the other factors and just look at the weight.'

According to legend, that's exactly what Galileo did. He made two balls, completely identical except that one was made of lead and the other was made of cork. He then dropped those balls from the top of the Leaning Tower of Pisa. Despite the fact that the lead ball was much heavier than the cork ball, they both hit the ground at exactly the same time. This story, if it is true, is one of the first recorded scientific experiments in history.

The Importance of the Scientific Method

So, what differentiates Galileo's experiment from our observation of the feather and apple? Well, first of all, Galileo was able to separate one factor from another. Instead of saying that apples and feathers fall at different speeds because of their weight, Galileo thought that they fell at different speeds because of their shape. Second, instead of just stating his theory and supporting it with reasoning, Galileo decided to test his hypothesis by conducting an experiment. Finally, his experiment showed that Galileo understood the limitations of human observation.

If we simply drop two objects a few feet, our limited senses might not be able to detect if one object fell before the other. They may seem to hit the ground at the same time because the difference is too small for us to notice. However, if we drop our two objects from the top of a tall tower, we can spread out the phenomenon and give our senses a chance to notice even small differences.

With the aid of a telescope, Galileo confirmed that the heliocentric theory was correct.
Galileo Observes Orbiting Heavenly Bodies

This was a whole new way of looking at the world. Galileo's method demanded more than observation and explanation. It required an examination of the factors involved and, most importantly, proof. In this sense, Galileo joins the ranks of Francis Bacon and Rene Descartes as fathers of the scientific method.

Telescope and Starry Messenger

Galileo applied this new scientific method to the matter of heliocentrism. He would prove, once and for all, that the earth orbited around the sun, not the other way around. Yet to do so, he was going to have to build a new tool, something much more challenging than balls of lead and cork. Galileo needed a telescope.

Luckily for him, in 1608, a series of Dutch craftsmen had invented the telescope. A year later, in 1609, news of the telescope reached Galileo. The day after he'd heard about the Dutch telescope, Galileo had already built one of his own. The first telescopes were quite weak, only capable of magnifying something to three or four times its normal size. Galileo gradually improved his technique until he had constructed a telescope 33 times more powerful than the naked eye, thereby overcoming the limitations of human observation.

Taking this new tool in hand, Galileo turned it towards the heavens, and the things he saw proved once and for all that the heliocentric theory was right and the old geocentric theory was wrong.

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