“i went to a friend's house. he said, ‘you have to sleep on the floor.’ [darn] gravity,...

“I went to a friend's house. He said, ‘You have to sleep

on the floor.’ [Darn] gravity, got me again. You

know how bad I wanna sleep on the wall.”

Mitch Hedberg

Universal Gravitation

Part 2

The Dark Ages

• They were called that for a reason

• Very little science was done in this era

• Most work on gravity still consisted of further proofs of Aristotle’s flawed ideas

Copernicus

• In 1543, Copernicus was on his deathbed

Copernicus

• He permitted one of his fellow monks to publish a book that he had written 20 years earlier

On the Revolution of the Heavenly Orbs

• Copernicus brought back the forgotten heliocentric model

• He was reluctant to publish the book because he knew what he affect would be

Why was it a big deal?

• The Ptolemaic model had been the standard for more than a millennia

• The Church had built it’s beliefs around it

Copernican Model• Got rid of most

of the epicycles

• Only the moon’s remained

• Very similar to what we use today

Tycho Brahe• Tycho was a Danish

noble• With the support of the

Crown he was able to build the finest observatory in the world

• Tycho was an interesting man

Taking things too seriously

• Tycho was a mathematician• At university he got into a duel

to settle an argument about math

• In the dual he lost part of his nose

• He had a silver and copper prosthetic

A Step Back

• The Tychonian system put the Earth at the center of the universe again

• The Sun orbited the Earth and all other planets orbited the Sun

Bad Math

• Tycho was a bad mathematician

• That might be why he lost his nose

• He had the data but not the skill to understand it

Wandering Mathematicians

• Kepler was hired to do the math that Tycho Brahe could not

• Tycho never fully trusted Kepler, so he kept most of the data to himself

A Bad Way to Go

• Tycho died of a ruptured bladder caused by not going to the bathroom at a dinner party

• No joke

Dying Words

• “Let me not seem to have lived in vain.”

• The Brahe family still refused to give the data to Kepler

Kepler

• He had a tough life

• If you think living today is hard, and you do, imagine…

A Bad Life

• Born out of wedlock

• Abandoned by daddy

• Aunt burned at the stake for being a witch

• Mother accused of being a witch

Not to nit pick, but…

• He had bad eyesight• He was constantly ill• On top of all that, he

couldn’t find steady work and had to wander about, casting horoscopes and doing math

Kepler’s Model

• He was fascinated with the Copernican Model but had modified the geometry of it

The Data

• Kepler was an empiricist

• He wanted data to back up his ideas

• This is where Tycho Brahe came in

The Brahe Family

• Tycho’s family refused to give Kepler the data

• So, he did what any self-respecting scientist of dubious background and questionable morals would do

He stole it!

• Would any of you be so persistent?

• It took Kepler 30 years and over 900 pages of calculations to complete his work

• It yielded only 3 things

Kepler’s Laws

Kepler’s First Law

• Planet’s travel in elliptical, not circular, orbits

Kepler’s Model

• His geometric model originally had circular orbits

• Brahe’s data showed the orbit’s to be elliptical

• The big step was when Kepler decided to trust the data instead of the dogma

Kepler’s Second Law

• A line from the Sun to a planet sweeps out the same area in an equal time

Kepler’s Third Law

• Kepler found a mathematical relationship between the orbital period and orbital radius of any given planet

23 /TRK

“… more things in heaven and earth …”

• The study of the heavens has still continued, separate from the study Earthly gravity

• There have been no advances in thought on gravity, until…

Galileo Galilei• The first

person to really try and rework Aristotle’s Physics

Birth of Science

• Galileo refused to take things at face value

• He demanded observation and experiments to verify his conclusions

• This was a new concept

Big Ideas

• Galileo found that items fall at the same rates, regardless of mass

• Objects will continue to move unless stopped, without need of any extra force

Other Big Ideas

• He proposed the idea of inertia

• It was what kept things from flying off of the Earth as it revolved around the Sun

The Telescope• He was the first person to

use the telescope to observe the heavens

• It could magnify objects up to 21 times

Drawings

The Rebel

• One of the biggest chances Galileo took was writing his works in Italian instead of Latin

• The Church didn’t like what this man was doing

The Church• It viewed Galileo as a problem

and his work was denounced as heresy

• He was put on trial and forced to renounce his discoveries, or else face torture

• At the trial he was heard to say…

“Eppur, si mouve”

“Nevertheless, it [the Earth] moves

Newton

• Born one year after the death of Galileo

• Was able to combine the efforts of those who came before him

The Apple and the Moon

• Newton did not come up with his ideas because he go hit in the head

• He compared the motion of a falling apple to the motion of the moon in its orbit and found them to be the same

“If I have seen farther than most, it is by standing on the

shoulders of giants.”

Synthesis

• Newton showed that gravity was the force that not only pulled things down to the Earth but also moved the planets