Exam 2 Flashcards
(21 cards)
Retrograde in Copernican
Was able to explain why planets are brighter in retrograde with his system, with advantage of uniform motion instead of Ptolemaic’s equant points.
Copernicus’ Motovation
- Neoplatonic Beliefs: thought sun was center because of religious Neoplatonic beliefs. “Good”=God=center=sun
- used Uniform Motion Point, since Ptolemaic system requires Equant point, which didn’t sit well with Copernicus
Tycho Brahe’s main contributions to science (2)
1) developed system that united perceived advantages of Copernican system while remaining true to geocentricity of Ptolemaic system (moon/sun revolve around Earth, planets revolve around Sun)
2) best naked eye astronomer tabulated tons of years of data on celestial bodies
Tychonic vs Copernican
Copernican heliocentric, tychonian geocentric
Main components Copernican System
- Heliocentric
- epicycle system using Ptolemaic beliefs
- no Equant points (major advantage)
Significance of Tychonic system
Moon & sun revolve around earth, planets revolve around sun
Significance of Kepler system
Got it ‘right’ if believe in Heliocentric system
Main features of Kepler system (2)
1) planets move in elliptical orbits
2) speed of planets vary along the orbit
Kepler’s Motivation
Kepler also Neoplatonist (good=God=sun=center of universe)
Desire to read the mind of God. Convinced God had blueprint of universe
Galileo’s discoveries (6)
1) mountains on the moon: moon isn’t as spherical as thought
2) sunspots: there are sunspots on the sun. (Sunspots = regions of intense magnetic activity)
3) ears of Saturn: saturn has rings, irregularly shaped
4) Moons of Jupiter: jupiter’s moons orbit Jupiter
5) Phases of Venus: confirming evidence for hello system. Can’t explain phases with geocentric systems
6) stars: more stars than you can see with naked eye
Significance of Galileo’s Discoveries
1) Moon: mountains on moon mean moon isn’t perfectly spherical as originally thought
2) Sunspots: maybe super-lunar region isn’t region of unchanging perfection that we originally thought it was
3) Ears of Saturn: maybe heavenly bodies aren’t perfect spheres. Couldn’t be composed of ether because ether is perfect.
4) Moons of Jupiter: maybe we aren’t the only center of rotation in the universe
5) Phases of Venus: Can’t explain phases with geocentric system. Requires substantial changes be made to worldview. TIPPING POINT.
6) Stars: Universe is very large?
Reaction to Galileo’s Discoveries
Church approved of helio model, but it was taught with instrumentalist attitude. Galileo wanted it taught with realist attitude. Church not happy about that. Book was banned after it was ‘okay’d” by Church, Galileo jailed, made to formally declare that helio system was false.
Why does Galileo’s discoveries present a problem for AWV?
- Transitional period that raised a lot of questions without answers.
- Core pieces of the puzzle are tossed out, nothing to replace in AWV’s puzzle with Galileo’s discoveries.
- Presented a need for a new science
Atomism
Tiny indivisible particles that couldn’t get smaller and would move in a void until something else interacts with it. Atoms at rest will stay at rest.
- paved way for Newton’s 1st law, principle of inertia.
- less outrage over newton’s 1st law because we already had atomism.
3 laws of motion
First Law - an object in motion stays in motion & an object at rest stays at rest.
- inertia
- shopping cart example
Second Law - a change in motion of a body is proportional to the force on that body.
- F=MA
- weak person vs sumo wrestler pushing on me
Third Law - For every action, there’s an equal & opposite reaction.
-Gun example: bullet goes forward, gives gun recoil
Universal Gravitation
As distance between objects increase, the forces between them decrease exponentially.
-seen as spooky action at a distance, an invisible force that can’t be seen.
NWV: Major advances in Biology, Chemistry and Physics
All: Newton’s laws allow us to be more quantitative about chemistry, biology and physics
Biology: in AWV, thought there was difference in the ways a living and non-living object behaves. With Newton, living & non-living objects behave in accordance with forces on them
Chemistry: With Newton’s laws, chemists realize a gas is just an object that behaves because of a force on it, in accordance with Newton’s laws
Physics: advances in electricity and magnetism
Michelson-Morley Experiment
water waves requires water, sound waves require air. What is the underlying medium for light? MM thought it was aether, so they tested for presence of Aether Wind.
Set up experiment with light, beam splitter, mirrors and detector, thinking rays of light would return to detector at different times, but light returned at same times
-no ether winds means no ether, which was the end of AWV.
Final nail in coffin, no ether=no super-lunar region
Postulates of Special Relativity (2)
Principles of the Constancy of the Velocity of Light: speed of light, C, will always be measured at 3x10^8 m/s in a vacuum.
-light behaves very differently than other objects
Principles of Relativity: There’s no privileged vantage point from which to say who is in motion & who is at rest
-we have to speak of motion as relative to a point of view
Time Dilation
Time is not absolute, time is based on the observed
- light bulb train example: path that light takes to travel in moving clock is longer than path in stationary clock. Light is moving at C for both clocks, moving clock “runs slow” relative to stationary clock.
- time intervals are dilated/expanded between ticks
Length Contraction
-Space contracts
-Time expands
distances shrink for objects in motion relative to a stationary object.
