PHU 2 Flashcards
Astronomer hired by the church to study the heavens
Copernicus
Copernicus’ model of the universe
planets aligned perfectly
wrote the book “On the Revolutions”
-planets revolving around the sun
Copernicus
came up with the first new heliocentric model
-this made the Catholic Church wrong
-explains retrograde motion with lapping
~we’re moving!!
-everything is still circles
Copernicus
How Copernicus un-pissed off the church
1) Releases his book on his deathbed
2) Writes the book in Latin
-writes to the highly educated
3) Dedicates it to the pope, allowing him to determine worthiness and ‘own’ the idea
4) Doesn’t claim truth, simply explains that the math works
Occam’s Razor
the simplest idea is the best one
Why the church rejects Copernicus’ idea
2 centers
-the universe won’t have more than one center
Copernican Revolution
1) The Greeks don’t know everything
2) Overthrow the idea that we’re the center of the Universe
-psychological issue!
3) Challenging the church
his model winds up not being any more accurate than Ptolemy’s
Copernicus
receives the Mars data
Kepler
Kepler’s model of the universe
The orbit of each of the planets is an ellipse, with the Sun at one focus.
wrote a book called ‘Laws of Planetary Motion
Kepler
First Law of Planetary Motion
Planets orbit the sun in elliptical orbits with the sun at one focal point (almost circular)
-the ellipses are independent of each other
Second Law of Planetary Motion
A planet sweeps out equal area in equal time
-the planet is going faster near the sun
-would’ve been surprising to Aristotle because he thought the speeds of the planets were unchanging
Third Law of Planetary Motion
There’s a mathematical relationship between the average distance between the avg. distance between a planet and the sun and the time it takes to complete an orbit and you can compare two of them
-Inner planets are moving faster than outer planets
-Same for anything orbiting anything
Law
describes a fundamental relationship in nature
1) May or may not be mathematical
2) Is based on observation or evidence
3) Is accepted as true because it is so consistent
4) Is assumed to be universal
5) Can change over time
theory
explains a fundamental relationship in nature
if you drop a heavy thing and a light thing they will fall at the same speed
-in conflict with Aristotle
-happened in Piza
Galileo
trust your senses
-in conflict with Plato
Galileo
first person to improve telescope and look at heavens
Galileo
Observation: Sees mountains, valleys, and seas on the moon
Galileo
Significance: the moon isn’t a perfect sphere like Aristotle believed
-if so similar to Earth, is it possible Earth isn’t special?
Observation: Saw sunspots on the sun that moved around, shrink, and grew
Galileo
not orderly/perfect
Observation: Found 4 moons around Jupiter
Galileo
Significance: -more than one center (against the Catholic Church’s argument for rejecting Copernicus’ model)
-repeat about moon arguments
Observation: Saw the phases of Venus (crescents and gibbous-es)
Galileo
Significance: If Ptolemy’s model was correct, Venus would always appear as a crescent
-Ptolemy is wrong
-heliocentric model is right
Why do moon phases happen?
As the moon moves around us, we see different percentages of the lit side of the moon
Newton
invented calculus
studied light
-prism
-proposed light was corpuscular (discrete)
-stuck needle b/w bone and eye to test force
-white light is made of all colors
newton
ran the English mint
-put ridges on coins to prevent workers from shaving off silver
newton
First Law of Motion
An object in motion tends to stay in motion, and an object at rest tends to stay at rest unless acted upon by some outside force.
inertia
Galileo
measure inertia
mass
Second Law of Motion
a=F/m
acceleration=Force over Mass
acceleration
to speed up, slow down, or change direction
force
a push or a pull
-directly proportional to acceleration
-forces cause acceleration
Why didn’t Aristotle come up with the Second Law of Motion?
he only considered F
Third Law of Motion
For every force, there is an equal and opposite (in direction) return force.
-one interaction, two things feel it
-just replace the nouns
-doesn’t mean equal response (car/bug ex.)
sideways speed
tangential velocity
Inverse Square Law
-gravity obeys this
-anything that radiates out from the center obeys this (ex. light, spray can, sound, butter and toast ex.)
The Law of Universal Gravitation
F= force of gravity between ANY two objects with mass
G= a constant
m1 and m2= the masses of the two objects (in Kg)
r= distance between the two objects from center to center
mass and force are directly proportional
had a better model than Ptolemy
brahe
geocentric model
brahe
Bar fight, nose, pet moose
brahe
An astronomer, hired by the church, ‘runs’ a summer palace
brahe
Builds better measurement tools for things in the sky
brahe
while having dinner with the King, his bladder tears and he dies after about two weeks
brahe
MARS DATA
-if he figures out retrograde motion, he can figure out the universe
-hoards the data
-rotates jobs of employees so that no one person can have it all
brahe
identified a supernova
-we can find it now with his recorded measurements
brahe
