“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
Jan 17, 2016
“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