Essay Questions 1 Flashcards
- Explain the Quine-Duhem thesis. Explain how it pertains to falsificationism and related views (such as ‘crucial experiments’) about the relations between evidence and theories in science.
The Quine-Duhem thesis basically claims that the key idea of a hypothesis cannot be tested in isolation; rather, we test a body of claims.
This is related to the jigsaw puzzle/building analogy concerning ‘core beliefs’–certain beliefs can be changed easily because they are not core beliefs; core beliefs being changed requires altering one’s entire worldview. Quine made a spiderweb analogy for basically the exact same concept. Because ideas/beliefs are interrelated/connected (making a web, or a puzzle, or whatever), the test of a hypothesis is not the test of a single hypothesis, but rather a collection of beliefs. Are we testing a subset of our beliefs, or, each time an experiment is conducted, are we testing our entire belief system?
Quine believed any central belief could ultimately be revised, which means he believed the whole worldview was put to the test every time–he called this the tribunal of experience; Duhem believed that we could and do test subsets, therefore we do not put our worldviews to the test very often.
The idea of crucial experiments is that: when faced with two opposing theories, one should be able to test them against one another and prove at least one of them false via a crucial experiment. Even if it didn’t prove one of them correct, it would prove one of them incorrect. But according to Quine-Duhem, experiments underdetermine theories in that a theory makes general statements about phenomena based on testable hypothesis. If an experiment proves a hypothesis wrong, it is possible to maintain that the hypothesis was external and not central to the theory.
A good theory is based closely on hypothesis to the extent that it the hypotheses were proved false the truth of the theory would follow accordingly.
- Explain the two-sphere model, its strengths and weaknesses in accounting for astronomical observations.
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- Summarize Aristotelian Cosmology, including the four elements, natural motion, simple motions, plenum theory, and the reasons for the finiteness of the Aristotelian Cosmos.
Aristotle theorized that the earth as we know it was made up of four elements, earth, air, fire. and water. He argued that each element had certain properties that determined its place in the universe. He believed that Earth’s natural place in our universe was the center of our universe thus it sinks lower than any other element. Next was water whose natural place was as a sphere around earth. Air’s place belonged in a sphere above water. Fire tended towards the sublunar sphere or the sphere in which we find the moon. When an element is moved out of its natural place it naturally moves back towards the natural order this is called natural motion. Aristotle argued that the universe was a fixed entity. Basically he subscribed to the plenum theory, the idea that nature will always fill a vacuum, when there is one so there was no reason for the universe to not be finite. He argued because there were no boundaries at the outset of our universe then there must be nothing beyond them
- Summarize Copernicus’ heliocentric model. Summarize Copernicus’ main arguments for his model over Ptolemaic models, and his arguments for the possibility of the Earth’s motion. What were the chief obstacles to the acceptance of the Copernican model?
Copernicus developed a rather simple model that followed the following guideliness
1. Heavenly motions are uniform, eternal, and circular or compounded of several circles (epicycles).
2. The center of the universe is near the Sun.
3. Around the Sun, in order, are Mercury, Venus, Earth and Moon, Mars, Jupiter, Saturn, and the fixed stars.
4. The Earth has three motions: daily rotation, annual revolution, and annual tilting of its axis.
5. Retrograde motion of the planets is explained by the Earth’s motion.
6. The distance from the Earth to the Sun is small compared to the distance to the stars.
This argument is made for a few reasons one it accounts for qualitative features of observed orbits quite nicely. It gives natural explanations to some phenomena that the Platonic model is unable to account for. Also the arguments against this model do not compel anyone to doubt the copernican model. Arguments such as “the world would fly apart if it moved” can easily be dismissed by assuming if it is natural for the earth to rotate then it won’t fall apart by turning.
Developed a model that accounted for retrograde motion. Also gave an account of why venus and mercury were always so close to the sun.
- Explain Tycho’s role in the Copernican Revolution, including his cometary and nova observations, his Tychonic model, and his relation to Kepler.
Greatest naked eye observer. Used Copernicus but unlike Copernicus he placed the Earth at the center of the Universe. He used Copernican math for his model but developed it’s physical properties from more pteulomaic in terms of its physical experiences. However he orientates the planets on epicycles going around the sun. he believed the Copernican model created too much wasted space. Tycho observed a number of events that lead him to believe that the universe and sky of the earth was mutable and could change. Tycho argued for a stellar parallax that would mean that the positions of the stars relative to the earth would change at times based upon the posistioning of the earth.
- Summarize Kepler’s role in the Copernican Revolution. State his laws, and explain his relation to Tycho. Explain his improvements to the Copernican model.
Greatest naked eye observer. Used Copernicus but unlike Copernicus he placed the Earth at the center of the Universe. He used Copernican math for his model but developed it’s physical properties from more pteulomaic in terms of its physical experiences. However he orientates the planets on epicycles going around the sun. he believed the Copernican model created too much wasted space. Tycho observed a number of events that lead him to believe that the universe and sky of the earth was mutable and could change. Tycho argued for a stellar parallax that would mean that the positions of the stars relative to the earth would change at times based upon the posistioning of the earth.
- Summarize Galileo’s role in the Copernican Revolution. Explain the relevance of the moons of Jupiter, sunspots, the phases of Venus, and millions of new stars.
First person to use a telescope to discover sunspots, the moons of Jupiter, the phases of Venus, and the rings of Saturn. Also discovered millions of new stars, and identified lunar imperfections. The moons of Jupiter shown that there were bodies that moved around the planets while the planets were moving. The phases of Venus showed that at least Venus orbited the sun. The new stars showed that the universe could be larger than people originally thought
- Summarize Leibniz’s argument against substantivalism on the basis of the principle of sufficient reason.
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- Summarize Newton’s ‘bucket experiment’. Give Mach’s response. Is it satisfactory? Explain.
Newton basically filled a bucket with water and attached the bucket to a cord that was strung so the bucket was not touching the ground; Newton then twinned the cord around itself. Once he released the cord the bucket began to spin as the bucket spin so did the water. Eventually as the water and the bucket begins to pick up speed it forms a concave shape, even though the bucket and the water were moving at the same speed the water in the bucket formed a concave shape. Now Newton stops the bucket but the water continues to rotate and maintains its concave shape until it slows down. Since you cannot know what the shape of the water looks like as it is rotating by looking at the bucket it must be rotating from an absolute force. Mach argued that force couldn’t be absolute. He hypothesized that if there were a universe were only the water spinning existed that it would not create a concave shape. Because there is nothing pulling on the water it would have no reason to become concave. it is only once we begin to add the gravity of other objects in our universe that we begin to see concavity in the water because of the mass of other objects attracting the spinning water to them. The response makes sense. The reason the water forms it’s concave shape is become as it moves the earth is still pulling down on the water even as it is trying to move apart because of the spinning without the mass of the earth the force acting on the water via the bucket would only cause the water to go in circles with no concavity.
- Mention five novel consequences of Einstein’s Special Theory of Relativity. List two or three experimental verifications of the theory.
Time passes slower for things in motion
things can’t move faster than the speed of light
the speed of light is the same in a vacuum This isn’t a consequence. The speed of light being the same in all reference frames is an axiom of special relativity.
Whether two events are simultaneous relative to your frame of reference. aka if you fly by something super fast, you’ll see it differently (smaller) than it actually is.
What is the fifth?
Experiments to measure the speed of light: tried to measure the distance of light the light had to travel if going from one place to another, but no one was ever able to find a difference in the speed of light.
Experiment: twin paradox case. The “twin paradox” wasn’t an experiment. It’s a consequence of time dilation.
Experiment: Michelson-Morely interferometer
- Discuss the idea of delayed-choice experiments, and their significance for interpretations of quantum theory.
version of the two-slit experiment, but instead of photo paper at the back, use a bunch of detectors. The detectors change the result every time. You can turn them on after your fire the electrons, and the particles will show up as a clump rather than bands (signalling particles rather than a wave). No one understands why this is happening, but it seems as if backwards causation is affecting how the particles were in the past.
- Explain the two-slit experiment, and why it is puzzling.
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- Explain the difference between epistemic vs. ontological/metaphysical interpretations of quantum probabilities and the wave function. Explain how various interpretations of measurement address this question.
When you shoot electrons through a slit they behave like particles. When you shoot electrons through two slits they behave like a wave. If you shoot electrons slowly through two slits the receptor site registers a particle, when the speed of the electrons being shot through the slits increases, the electrons interfere with each other and generate a wave pattern. If you place a detector next to the slits the electrons behave like particles.
- Explain the EPR thought experiment, and what EPR believed that it showed. Summarize the impact of Bell’s theorem on the possibility of hidden-variable theories, or more generally theories that suppose that things have determinate properties whether they are observed or not.
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- Explain what a hidden-variable theory is, and the role of Bell’s theorem in undermining the plausibility of such theories.
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