这学期在看的东西，里面古人/现代人对近代物理的哲学思考都挺有意思的，写篇总结（大概算吧）纪念一下。大部分是考试前看书自己的一些总结，因为比较喜欢碎片式记忆方法，所以内容比较零散。
1. Pre-paradigm “science,”
Paradigm is beneficial because it gives direction to research. It is essential to thought it self. In the evolution of any scientific field there is a pre-paradigm period which refer to “random fact gathering”.
2. Normal science
Once a paradigm has become accepted, scientists fill in the details within the structure that the paradigm supplies. Normal science is trying to solve the problem in the given paradigm. Kuhn thinks that normal science is not to come up with new phenomena. Also, when a paradigm conflict with the evidence. you see it as a “problem to be solved.” In other words, you assume that there is some way to shove it into the paradigm, you just haven’t figured out that way yet.
3. Anomaly
An anomaly is an “apparent” conflict between evidence and the theory, or paradigm. Kuhn thinks within normal science the scientists never see an anomaly as counter evidence to the theory.
Three basic response:
a. It’s either not seen at all or ignored.
b. It’s left for future scientists to solve.
c. Add modifications are made to the theory.
4. Crisis
Anomaly does sometimes lead to crisis. Kuhn thinks, for example: If there is some problems that hasn’t been solved. it might come to seem like the most important problem in the field, but there is no general rule about how and why this happens.
5. Revolution
The paradigm itself is replaced by another. The new paradigm never answers all the problems in that field of science. What it does is it answers the problems that led to the crisis. Then we’re back to normal science, where the problems that the new paradigm hasn’t solved are viewed as “problems to be solved.”
6. Incommensurability
Our beliefs don’t come in individual units, rather they form a system, each one is mutually supportive of all the others. The meaning of any individual word doesn’t stand alone. Words (or concepts) take their meanings from the other words and concepts within the paradigm.
7. Why does Kuhn think that “pre-paradigm science” is not really science?
He thinks pre-paradigm science is not really science because of something you have already said earlier: science, maybe thinking itself, needs a paradigm, or it is just random fact gathering.
8. We hear that it is cool to “think outside the box” What might Kuhn say about that?
Because a paradigm is necessary for thought to take place at all. If we thought outside the box all the time (i.e., thought outside the paradigm), it would be like being in a pre-paradigm period.
9. What is “belief holism”?
Our beliefs don’t come in individual units, rather they form a system, each one is mutually supportive of all the others. Kuhn is also a meaning holist. The meaning of any individual word doesn’t stand alone. Words (or concepts) take their meanings from the other words and concepts within the paradigm.
10. What is Kuhn’s conception of scientific progress? (What is his Darwin analogy concerning scientific progress?)
For Kuhn, though, scientific progress does not consist in a linear march toward objective truth. Instead, there is progress when a paradigm changes, but it is not progress toward "objective truth."
11. What is the common view of the relation between Newtonian physics and Einsteinian physics (with respect to scientific progress) and what is Kuhn’s view? (This is in ch. 9.)
The issue is that people think that Einstein is talking about the same issues as Newton, he just got a little more accurate on those issues. Kuhn says, no, it's a different paradigm, they aren't even talking about the same things.
12. What is Popper’s view of science, and how does Kuhn’s view differ?
Science is the great invention of Western Thought.
Throughout its 2500 years history, the goal of science has generally been seen to be: an objective account of the world.
There have been two major schools of thought concerning how we get to objectivity (and therefore concerning how science works):
1) Rationalism
2) Empiricism
Differences
Popper says: real scientists, if they get counterevidence to their theory, they throw it out.
Kuhn says: if you actually look at the history of science, you see that science does not work that way.
Every paradigm has counterevidence (anomalies) from day 1.
But the scientists who hold the paradigm don’t interpret the anomalies as counterevidence. The see them as “puzzles to be solved.”
13. The common interpretation of Kuhn is that he is a relativist about truth. How does Kuhn respond to this criticism?
Firstly, Kuhn denies this: we cannot know the world independently of all paradigms. He thinks we cannot directly interface with the external world, the objective world.
14. What does it mean to say that Aristotle’s physics was teleological? That for him matter is “active”?
For Aristotle’s teleological view, an object has an internal impulse to move toward its goal.
15. Why (and how) did Aristotle distinguish between natural motion and artificial motion? How did this view of motion lead to a radical distinction between “heavenly” (circular) and “earthly” (straight line) motions?
Natural motion: the motion is due to something internal to the object (like an acorn wanting to become an oak tree.). artificial motion: it is due to something external to the object (like me cutting down the tree and turning it into a table).
16. What does it mean to say that for Aristotle space is not homogeneous? You might think of examples of incommensurability between Aristotelian and Newtonian physics (we discussed the explanation of projectile motion.)
For Aristotle, space is not homogeneous. Space is subordinate to “place.” Space has a center (the place to which things made of the element earth go), then it has layers (the places to which water, air, and fire go.)
Space is not infinite. The “fixed stars” are all at the same distance, and there is nothing beyond them.
17. What is materialism?
According to Democritus: "Nothing exists but atoms and the void." Materialism is the claim that all that exists is matter (and space, and time.)
18. What is determinism?
Determinism is the view that no events happen at random, and there are no events that are unpredictable.
19. Why does determinism, according to Capek, lead to the “implicit elimination of time” in classical physics? What does this have to do with Parmenides?
Because according to determinism, everything is predictable. Therefore, the future of the universe is completely built into the present moment. It also shows the shadow of Parmenides on Western thinking. Because for Parmenides, Change requires not-Being, there is no not-Being, so there is no change.
20. Galileo distinguishes between primary and secondary “qualities” of matter. What does this mean? Why is it significant?
The primary characteristics of matter, for the ancient atomists, were the geometrical/mathematical properties of the atoms: their shape, size, and motion. The secondary things are those things you and I refer to as qualities: taste, smell, hot and cold, color, and so on. Only primary characteristics are really real, or in the world, or objective; secondary characteristics are in me, not in the world. It is significant because you can give a description of the world that is completely separate from the person giving the description.
21. What are the chief features of the classical view of space? Think of some differences with Aristotle.
The basic relationship in space is juxtaposition, and this is three-dimensional; the basic relationship in time is succession, and this is one-dimensional.
For Aristotle, he thinks space as three-dimensional. It is a container that contain everything in the world, and it could be separate with the object it contains.
22. What are the chief features of the classical view of time? Again, what is the Gulliver thesis?
The basic relationship in space is juxtaposition, and this is three-dimensional; the basic relationship in time is succession, and this is one-dimensional.
1. It is homogeneous. All seconds are the same.
2. It is independent of its contents.
3. It is infinite.
There can be entities living so that their lives are sped up, or slowed down, relative to us – but that doesn’t affect their subjective experience
23. What is eternal recurrence and how does it follow from (some interpretations of) the classical view of time?
Eternal recurrence was one interpretation of this concept of time. It was held by a number of post-Newtonian physicists and mathematicians. Eternal Recurrence is basically the idea that the universe is just a big deck of cards. Given infinite time, it will repeat itself.
24. What is a corpuscular-kinetic view of matter?
The kinetic theory of matter states that all matter is made of small particles that are in random motion and that have space between them.
25. What are the chief characteristics of the 17th c view of motion?
1) All motion is external to matter. In other words, anything that moves needs something external to move it.
2) ) An object in motion is changing its spatial and temporal coordinates, but it is not undergoing any sort of qualitative change
26. What is Galilean Relativity?
It is Newton’s first law. It only has a reality relative to an arbitrary coordinate system, or relative to another object. Also, it is the fundamental laws of physics, all frames of reference moving with constant velocity with respect to one another
27. What is the connection between Galilean Relativity and Newton’s first law of motion?
Galilean Relativity is the first theory that against Aristotle’s theory about motion. He denies Aristotle: force is the thing that maintaining the motion of an object and make people re-think the relationship of motion and force. Then, Newton proposed Newton's first law.
28. What does it mean to say that, built into Newton’s first law (or built into Galilean Relativity) is the conception of matter as passive?
Because according to Newton’s first law: object at rest stays at rest, an object in straight line constant speed motion stays in straight line constant speed motion. Therefore, in order to change the motion of an object. It needs to be given an external force. Therefore, the conception of matter is passive
29. So, what is “mechanistic philosophy” anyway?
Mechanistic philosophy asserts that all life phenomena can be completely explained in terms of the physical-chemical laws that govern the inanimate world.
30. What is the problem of action-at-a-distance?
Because anything that moves needs something external to move it. Or, all motion is by contact which does not make sense to action-at-a-distance because there is no external to move it.
Leibniz-Clarke Correspondence:
1. Leibniz’s philosophy seems pretty weird, but in fact a lot of his ideas triumphed over Newton’s in the end. (Though of course there hasn’t been an end…) How does Leibniz try to combine teleology and mechanism?
a) For Leibniz, he is trying to keep God in the picture by containing elements of Aristotelian teleological physics.
2. Partly he does it through the Principle of Sufficient Reason – what is that?
a) Principle of Sufficient Reason (PSR) = nothing happens without a reason; everything has a cause, nothing is random. Leibniz thinks God is responsible for these causes or reasons, he is invoking the universe has “intention” (God’s will), and that it is moving towards “perfection” (which is teleological).
3. Give some examples of how he applies this principle: to monads, to disprove the corpuscular-kinetic view, to disprove absolute space, and so on. (One of the immediate consequences of PSR is the Identity of Indiscernables – that plays a role here too.)
a) Argument against Absolute space: At this point, it seems like the issue is that if space is absolute, then there is this puzzle about the relationship between space and God. Leibniz wants to avoid the puzzle, so he denies that space is absolute. “Space is the order of coexistences, time is the order of successions.” But the argument he gives for why space can’t be absolute is that it conflicts with the PSR and Identity of Indiscernibles. So, if space is absolute, why didn’t God move everything to the left by 10 feet?
4. Leibniz’ goal was to combine mechanism and teleology. Newton on the other hand rejected teleology. But at the end of the Leibniz-Clarke debate, Leibniz is accusing Newton of not being mechanistic enough. Explain the criticism. (What is the problem of “action at a distance”?)
a) -Leibniz thought that mechanistic principles apply to the world of perception, but the real world (behind the world of perception) has these teleological elements to it. So in physics we can employ mechanistic principles, but in metaphysics we must realize that something deeper is going on.
5. What does it mean to say that, for Newton, space was “absolute”?
a) “Absolute Space” means that space, in its own nature, without regarding anything external, remains the same and immovable. Basically, Newton believed space was absolute, an unmoving reference point for what inertial systems (like planets and other objects) exist within it. As such, everything in the space has an absolute state of motion relative to it. Something is either at absolute rest or moving at some absolute speed.
6. Leibniz, on the other hand, has a relational view of space, or a relative view. What is at issue here?
a) Leibniz concludes, the problem is in conflict with the PSR and the PP. So, for Leibniz, the whole problem is logically impossible. Leibniz concludes that space and time are relative. Space is not a container. Space is merely distance-between-objects. If there were no objects in the universe, there would be no “space.” Space is not a “thing.” Likewise, time is how we measure distance between events. If there were no events, there would be no time.
7. Why does Newton believe in absolute space?
a) -First, like Leibniz, it seems to be connected to his conception of God. Space is a thing, and it is the “sensorium of God.” The second is a reason from physics. According to Galilean Relativity, position, and relative velocity, are not real. If there was only one object in the universe, it wouldn’t make any sense to ask: is it right side up or upside down? If there are only two objects in the universe, and the two objects flew past each other at a constant speed, it wouldn’t make sense to ask: which one is really moving?
8. What role does God play in Newtonian physics? (His view requires God to interfere with the universe in several ways – what are some of these?)
a) -Intervention argument: that the universe has gravity, yet it does not “collapse”, means God must be preventing this from happening. Also, other planets’ orbits have a gravitational effect on others, therefore, it must be God who is intervening to maintain the orbit.
b) -Intelligent design argument: reality seems to work based on mathematical laws, which implies a God.
9. Why does Leibniz accuse Newton’s philosophy of contributing to atheism?
a) Leibniz is concerned over the decline of religion, caused by the successes of natural science. Because, the ancient atomists were materialists; Leibniz is concerned with the reintroduction of the view. So, Leibniz’ first concern: atomism/mechanistic science is atheist.
b) Newton says that space is the “sensorium of God.” It’s hard to know what he was getting at, but it seems there is an analogy with Descartes’ mind/body problem: if the mind is completely different from the body, how do they interact? Another issue is that space is infinite, and infinity seems to be a property reserved for God, so it seems as though there is some connection between God and space. Anyway, Leibniz interprets this to mean that God is independent of the universe
10. How does Clarke respond to the accusation?
a) He admits that ancient atomism is atheistic, but not atomism correctly understood – which is mathematical atomism. What he’s getting at, is what today is called “intelligent design.” The fact that the atoms move according to mathematical laws shows that there is an intelligent creator, one who designed the blueprint, the mathematical laws.
b) Clarke responds to the sensorium of God issue by saying that space doesn’t mediate between God and reality; God is immediately present to all things.
c) Clarke says it is not an insult to God to say he has to adjust his machine; it shows that God is active rather than passive, constantly monitoring and intervening.
11. This is more or less the same thing as asking what role God plays in Newtonian physics – what are some of Newton’s arguments for the existence of God?
a) There is gravity between every object in the universe, yet the universe does not collapse. It must be due to God’s intervention.
b) Every planet has gravitational effects on every other planet; this makes their orbits unstable. God has to intervene.
c) Motion decays; some external principle (God) is needed to conserve it.
d) Matter is passive; some external principle (God) had to put it into motion in the first place.
12. How did Descartes and his followers deal with the action-at-a-distance puzzle?
a) -Since they had a "fluid" view of space, they thought all space was full of aether, a very thin fluid. "Gravity" then was just whirlpools in this fluid.
13. What are some of the puzzles raised by their view? (Capek discusses this from p.106-117. Einstein and Infeld also mention it, coincidentally, beginning on p. 106. You can check out their references to aether in the index, but notice that they spell it “ether.”)
a) One problem with this view is that the planets travel in ellipses, not circles. Whirlpools seem to imply circles.
14. On p. 92, Capek asks, “Do we really understand action by direct contact any better than action at a distance?” What is he talking about?
a) -If two infinitely hard atoms collide, they will rebound instantaneously. “Instantaneously” means zero time will pass, and they will be moving in the opposite direction. Another way to put this: there is an infinite acceleration.
b) -This is like dividing by zero in math, something that my fourth-grade teacher told me I can’t do.
c) When we run into something like this in physics, it is sometimes called a “singularity.”
15. What is there to not understand about action by contact? (Why is Leibniz bothered by it?)
a) -Leibniz, inspired by calculus, believed that all changes in nature are smooth. This is the basis of his Principle of Continuity. In other words, Leibniz (for philosophical reasons) rejects singularities. And Leibniz defends point-particles, that he calls monads
16. What is “entropy”?
a) -Irretrievable heat loss to the environment. Energy isn't lost, but it spreads out. “Entropy” is the spread-awareness of energy. (also, chaos/disarray)
17. What are two new ideas that the concept of entropy introduced into mechanistic science?
a) Energy is conserved. It has many forms, and energy can transfer between these forms, but it is never lost or created.
b) Though energy is not lost, it “spreads out.” Or: entropy increases.
18. Why did this seem to support a belief in aether?
a) Waves need a medium to wave through, like water waves travel through water. So, if light is a wave, it seems like space must have aether.
19. What was the Michelson-Morley experiment and why did it (together with the phenomenon of stellar aberration) cause problems for the aether idea?
a) Michelson and Morley devised an experiment to detect an aether wind. They established beyond a doubt that there was no aether wind.
b) But a previous result (stellar aberration) proved that there was.
c) The results of the experiment inspired the special theory of relativity, and the downfall of classical physics. This is related with the speed of light.
20. What was Oersted’s experiment, and why was it a problem for the mechanistic view?
a) -something about batteries & magnetic fields; what it showed: magnetic forces do not act in straight lines, rather in circles. He also proved action at a distance which directly contradict Newton.
21. How did Oersted’s experiment, and Faraday’s discovery of induced currents, lead to field theory? What is field theory?
a) Oersted discovered that electricity and magnetism were related, leading to the discovery of electromagnetism
b) Field theory is: A theory that explains physical phenomena in terms of a field and the manner in which it interacts with matter or with other fields. Field evolved from solving action at distance, the problem that newton had.
22. Einstein thinks that Maxwell’s equations are really great. Why? (see his discussion beginning on p. 142.)
a) This is because Maxwell’s equations “are laws representing the structure of the field.”
b) “In Maxwell’s equations there are no material actors. The mathematical equations of this theory express the laws governing the electromagnetic field. They do not, as in Newton’s laws, connect two widely separated events; they do not connect the happenings here with the conditions there. The field here and now depends on the field in the immediate neighborhood at a time just past.
23. Einstein doesn’t mention Boscovich’s name in his book, but he mentions Boscovich’s view in the middle of p. 151. You should know what this view is. Capek has several references to Boscovich in his index; he especially discusses Boscovich in the section from p. 92-99.
a) Boscovich represents the dynamic view, which saw the ultimate essence of matter in forces emanating from pointlike centers and acting instantaneously through distance.
b) Boscovich believes motion is born out of force, in other words, out of something that’s not a motion, and when it disappears, it’s transformed into something that’s not a motion.
c) Boscovich thinks the field exist in space and time. For Einstein, space time and matter are explained in term of field.
24. I guess a good exercise would be to describe the field idea as it’s found in Newton, Descartes, Boscovich, Faraday, Maxwell, and Einstein. Einstein’s views can be found starting on p. 240.
a) Newton - no real field idea
b) Descartes used aether explained action at a distance
c) Boscovich used aether to connect to several of nature, repelling and attractive forces.
d) Maxwell used speed of light and found field phenomena to explain speed of light
e) Faraday- experimented with electricity and magnetism. Field lines part of space believes space is affected
f) Einstein: Same with Faraday.
25. Einstein thought he could do away with aether, but he likes the field idea. Is that inconsistent?
a) According to the general theory of relativity space is endowed with physical qualities; in this sense, therefore, there exists an aether.
b) According to the general theory of relativity space without aether is unthinkable; for in such space there not only would be no propagation of light, but also no possibility of existence for standards of space and time (measuring-rods and clocks), nor therefore any space-time intervals in the physical sense
26. What is the special theory of relativity?
a) The laws of physics, including electromagnetism, are the same in all inertial frames and can be stated in their simplest form in all inertial frames of reference.
b) Every observer measures the same value c for the speed of light (in vacuum) in all inertial frames. Put simply, speed of light c is constant in a vacuum no matter what reference frame an observer is in.
27. That is, what are its two postulates?
a) Putting these two postulates together implies (3rd Postulate) Galilean transformation laws don’t apply. Fitzgerald and Lorentz provided new transformation laws.
28. What is an “inertial frame”?
a) An inertial frame is a frame of reference where Newton’s laws of motion are observed
29. What does it mean to say, “special relativity violates the galilean transformation”?
a) Galilean Relativity Holds says the laws of physics are the same in all reference frames.
b) The velocity of light is constant in all reference frames.
c) Putting those two together implies: Galilean transformation laws don’t apply. We need new transformation laws.
30. In general terms, what does the Lorentz transformation say?
a) -Lorentz transformation: It’s not just that length will be contracted when moving relative to absolute space. Time too will be slow down. Lorentz came up with an equation for this.
31. Where is the Andromeda Galaxy/Nebula now? (Important)
a) “Now” only applies to “here”, there is no universally present “now”, as simultaneity is relative.
b) Time and space are deeply connected; there’s no absolute space or coordinate system.
c) This means the question is meaningless / unanswerable because it presupposes a false geometry.
32. How does this differ from what Newton said about simultaneity? If we can find a reference frame where B precedes A, and another where A precedes B, does that mean that an effect can happen before its cause?
a) -For Newton, time and space are separate entities. They are independent of one another. Newton claimed that simultaneity is absolute, it is not relative to a reference frame or observer’s location, , meaning that Event-A at location-X is occurring “at the same time” as Event-B at location-Y.
33. What is the “block universe”?
a) According to the growing block universe theory of time (or the growing block view), the past and present exist, and the future does not exist. The present is an objective property, to be compared with a moving z.
b) It’s the idea that all of space and time are already laid out in advance. What we perceive as “time passing” is only a subjective response and has nothing to do with objective reality.
34. Capek thinks that the classical concept that is most altered by 20th c. physics is time. Look closely at what Capek says about time in STR. (You probably should start on p. 143 with the chapter “The Negation of Instantaneous Space.” You at least need to look closely at the first half of the next chapter, “The Fusion of Space with Time and its Misrepresentation,” starting on p. 158. Also, look at the two chapters after that, “The Modification of the Concept of Time,” and “The Dynamic Structure of Time-Space.” So this is roughly p. 143 (or p. 158) to p.223. However, in all of these chapters, he begins with Special Relativity, and then he moves on to General Relativity (and in “The Dynamic Structure of Time-Space” he ends the chapter with Quantum Mechanics.) For the time being, skip the GTR and the QM stuff. What I want you to explain is what Capek thinks is the wrong way to interpret time in STR, and what he thinks is the right way. He calls the wrong interpretation “the fallacy of spatialization” (starting on p. 158.) So another way to ask this question: what does Capek mean by the fallacy of spatialization?
a) The STR links time and space in a way that Newtonian physics did not. It is common to refer to time as a “fourth dimension".
b) Capek thinks this is a mistake, it is a misinterpretation of the STR. Capek agrees that time and space are linked in the STR, but time is not best thought of as a fourth dimension. That’s because in STR, time has a direction. The universe evolves.
c) Space has no privileged direction (up, down, left, right, it’s all arbitrary.) But time does have a privileged direction. So time is not just “another dimension of space.”
d) Capek put time as a 3+1-dimension, time not reduced to space.
35. What causes it? Capek suggests that we replace the “spatialization of time” with “the dynamization of space” (p. 168.) What does this mean?
a) The idea that time acts outside of traditional views and is not merely a 3rd axis on a cartesian coordinate system but operating outside of it.
36. Why does he say “time-space” instead of the more usual “space-time”?
a) -when we speak of causally connected events, the length of the temporal interval between them may appear different to different observers, but in no reference frame does the effect happen before the cause.
b) -Therefore, we shouldn’t think of time merely as a “fourth dimension.”
c) -Thus it is more accurate to speak of time-space than of space-time; and while the term “temporalization of space” is not completely accurate, it is not so radically false as “spatialization of time.”
37. Capek vs Kant + Darwin vs Kuhn
a) Kuhn: We organize reality with paradigms, paradigm can change.
b) Kant: He thinks we interface with reality through “categories of understanding” which is kind of like Kuhn’s paradigm but unchangeable, hardwiring.
c) Darwin +Kant: an evolutionary account of this hardwiring.
1) General Theory of Relativity
The GTR is a field theory and a geometric theory of gravity that generalizes SR for accelerations in spacetime. It describes gravity as a curvature in spacetime.
1. You ought to have some idea of what the differences between STR and GTR are.
a. STR is relative. GTR is absolute. According to GTR, time slows down in a gravitational field, and also during acceleration. This is not relative to observers.
b. STR is related with inertial reference frames, reference frames moving at a constant speed in a straight line relative to each other. GTR deals with accelerations and non-inertial reference frames.
c. GTR also deals with gravity, F=ma, and F=Gm1m2r2
d. GTR is a theory about things that are really big, ex. black holes or stars.
e. GTR is a field theory, STR is not
2. You ought to have some idea of what a “noneuclidean geometry” is, and what it has to do with GTR.
a. Non-Euclidean geometry is geometry that does not follow Euclid’s 5 hypotheses specifically the fifth one. Because gravity in GTR is just geometry in spacetime, that geometry happens to be non-euclidean.
b. In simpler terms, it’s math without straight lines, it allows for curves (because gravity is like this).
c. GTR is a field theory, not in space and time but a field of space and time. Field affects space and time, curves space and time
3. You ought to know what Einstein means when he says the universe is “finite but unbounded.”
The universe is finite in its size, but you can never reach the edge. This is related with the definition of STR and GTR. Imagine trying to find the “edge” of a sphere - you can’t because it is unbounded. Still, the area is finite.
4. You ought to be able to say something about the role of the concept of field in GTR.
a. Maxwell thought of a "field" as some sort of "tension in the aether." Faraday thought of a field as some attribute of space itself.
b. For Einstein, he agrees with Faraday. He rejects the concept of "matter" altogether: "matter" is simply a region of space-time where the field is exceptionally strong.
c. In popularizations of GTR one often hears something like this: “mass causes space and time to warp.” Einstein would resist putting it that way, since putting it that way implies that we have two different things, mass, and space-time, that causally interact. Instead, Einstein is saying that these are different aspects of the same thing, which he understands via the notion of “field.”
5. You ought to know something about the “Big Bang.” (What was the evidence for it? What was Einstein’s “big blunder”?)
a. Matter, space, time, these three are all aspects of the same thing, and all exist with the Big Bang.
b. Evidence: All stars are moving away from us. So that we get the conclusion that the universe is expanding. Expanding away from an initial event. Call that the “Big Bang”.
c. Einstein developed with his GTR implied that the universe could be expanding. This scared him, so he threw in a constant to make that effect go away. Later, when Hubble showed that the universe actually is expanding, Einstein referred to the cosmological constant as the “biggest blunder of my life.”
6. You ought to be able to explain why Stephen Hawking says the question “what caused the Big Bang?” is a meaningless question.
Because the big bang was the creation and expansion of spacetime, there is no “time” before the big bang by definition and so you can’t ask questions about time and space before the big bang.
7. Feynman says that all of the mysteries of quantum mechanics can be found in the two-slit experiment. What is the “two slit experiment”?
a. A water wave will go through both holes and interfere with itself. When it hits the backstop, it won’t hit it in a specific place; there will be areas of higher intensity (where the peaks/troughs of the two waves constructively interfere) and areas of lower intensity (where the peaks/troughs destructively interfere, i.e., they cancel each other out.).
b. A bullet will either go through hole A or hole B. It will hit the backstop as a single lump. There is no interference. Right and left slit pile of bullets. The same number of bullets on each hole.
8. What is the “wave-particle duality”?
a. Bullet pattern versus wave pattern
b. Copenhagen Interpretation: particles versus probability wave, a phenomenon described by wave math
9. Einstein’s book suggests a hidden variables interpretation of quantum mechanics. What does that mean?
When we look at a system in terms of these macro concepts, the best we can do is talk in terms of probabilities. An individual atom doesn’t have a “temperature,” but what temperature is just the motion of individual atoms. On this view, macro reality might be probabilistic, but micro reality might not be; determinism applies to the motion of individual atoms. So though probability in physics is real, it’s not the whole story; there’s something more basic going on, at a deeper level, that is deterministic. Einstein wants to get rid of probability.
10. How does Bohr’s view (the Copenhagen view) of the probabilities referred to by quantum mechanics differ from a hidden variables’ interpretation?
This is basically Einstein’s response to the CI. From this point of view, when probabilities enter physics, those probabilities are related with our knowledge, not with reality itself. Einstein with reality. There is some deeper level of understanding – which we don’t yet have “God does not play dice,” in his famous statement.
11. Why is Bohr’s “Copenhagen interpretation” so radical?
a. At its heart is what Bohr referred to as “complementarity”: that reality has both a wave aspect, and a particle aspect, and that reality won’t show both of these at the same time, yet a complete description of quantum theory requires reference to both.
b. When we attempt to measure matter, it appears it “knows” it’s being observed and behaves differently. If attempting to observe, then light behaves like a particle; if we do not attempt to observe it, it acts as a wave. Which sounds ridicules.
12. What is the Schrodinger-cat paradox?
It shows what he saw as the problem of the Copenhagen interpretation applied to everyday objects. It presents a hypothesis that a cat that may be both alive and dead the same time, a state known as a quantum superposition, as a result of being linked to a random subatomic event that may or may not occur.
13. What is the Many Worlds interpretation of quantum mechanics?
They use parallel universes to explain the concept of two-slit experiment. In fact, any time any particle is “measured,” the universe splits.
Neither Kuhn nor Capek think it is right to say “Einstein’s physics reduces to Newton’s physics when v< 14. You should be able to explain how Einstein changed the picture, such that the word “motion” doesn’t really translate between Newtonian physics and Einsteinian physics. (You might start by briefly explaining “motion” in Newtonian physics: Euclidian space, an unchanging identifiable particle, and so on. Give some of the details concerning how STR deals with a different world than Newton’s. But concentrate on GTR. The GTR is a field theory. Just what does that mean, and how – when combined with the STR – do these two theories so radically alter “motion” that we should no longer use that word?) Newton: a. All motion is motion in space (relative to a Cartesian coordinate system.) b. An object in motion stays in motion, an object at rest stays at rest. So, all motion is due to external forces (there is no “natural” vs “unnatural” motion.) 15. Einstein STR: a. Matter and motion are connected, according to the equation E=mc2. For Newton, motion (i.e., energy) was a property that matter could have, or not (i.e., matter could be motionless.) For Einstein, matter is energy. b. Time and space are also connected. Moving faster in space means moving slower in time. c. The speed of light plays a role here. It’s a sort of speed limit, nothing can go faster than light. But it’s not just a speed limit; the fusion of time and space is connected to the speed of light. d. There is no absolute simultaneity. So, there is no such thing as “the universe at the present moment.” Determinism is apparently still true, but the classical statement of determinism is impossible since there is no “entire state of the universe at this instant.” 16. Einstein GTR: a. Time and space are also connected with mass, which is fused with energy. b. So, space and time are not connected. They are “curved” by "mass". We now realize this is the wrong way to put it. c. This is all understood via the concept of “field.” What we used to call “matter” is now seen to be a place where the field is strong. What we used to call “empty space” we now see to be a place where the field is weak. But there is no such thing as empty space since field is everywhere. The difference between “matter” and “space” is quantitative rather than qualitative Space and time are not a container. 17. Explain a couple of ways that Einstein is closer to Aristotle than to Newton. (The heart of Capek’s discussion is on p. 272, but this is a continuation of a passage starting on p. 262. (Then there is another important passage in the middle of 274.)) a. For both Aristotle and Einstein, “motion” is a sort of transformation, a process. b. For Aristotle and Einstein space is not homogeneous; space is not an empty container separate from its contents. Instead, the contents in the container affects the structure of space. c. For Einstein, motion is a field theory, a changing of the matter, energy, space, time medium. d. For Newton, space is homogeneous, space is infinite. e. Einstein and Aristotle object in motion goes similar change. For Newton new change is in coordinates for an object in motion. 18. On p. 314, Capek criticizes a passage that he quotes from a textbook on nuclear physics. What is the basis of his criticism? 19. What is Darwin’s theory of evolution? In other words, what does he mean by “descent with variation by natural selection”? Animals differ from one another; they pass these differences off to their children. Putting these two together, passing some changes of these differences is the decent with changes by natural selection. 20. How does his view differ from the evolutionary theories of his predecessors (most importantly that of Lamarck)? a. Lemarck thinks animal inherent towards a higher function. Animals pass on characteristics that were found to be useful in their life, and do not pass down elements that were disadvantageous. b. Thought it had a goal to be perfect, process use/disuse. 21. Natural selection isn’t the only mechanism that Darwin uses to explain evolution. He also talks about, among other things, sexual selection. What does that mean? How can these two be in conflict? (Give an example.) a. sexual selection- we have these standards of beauty, men to women. Conflict with the theory of evolution is that one characteristic could be advantageous in a situation like find a sexual partner, while in the same time disadvantageous in another situation unrelated to gene. b. Examples: It’s good for a peacock to have a big tail for mating, but bad because it’s a bigger target for food. In humans, outgoing people a higher chance of meeting more potential mates (good), but at the same time, loud people are more likely to get eaten by lions (bad). 22. Who was Malthus and what was his influence on Darwin? Malthus view: population growth is not controllable, it would for sure happens. Also, competition for food leads to suffering. Malthus makes the bases for Darwin on evolution. 23. Of course, Plato and Aristotle are outside the scope of this course. However, one of the main themes of the course is the “discovery of time.” Darwin plays a big role in that discovery. One reason Darwin’s theory is so radical is because it goes against this elimination of time that has been so influential throughout the Western tradition. You should be able (very briefly) to explain why/how the views of Plato and Aristotle led to a non-Darwinian picture of the universe. a. Plato and Aristotle do not agree of with the concept of changes, response to Parmenides that changing is real, but it’s framed by the unchanging and it’s the unchanging that’s real. b. Plato believed that everything in nature had a pure form, that does not change over time and exists metaphysically. 24. To put it another way, prior to Darwin the advance of a theory of evolution was seriously hampered by Parmenidean/ Platonist/ Aristotelian thinking. You should be able to briefly explain what this means. (this is connected to a topic we discussed earlier in the semester: the implicit elimination of time.) a. Parmenides - change doesn’t change. b. Plato- nothing really changes. c. Aristotle- everyday an object changes but not its overall structure. 25. People have seen all sorts of implications of Darwin’s views. One of those is Social Darwinism. What is Social Darwinism? The theory that individuals, groups, and peoples are subject to the same Darwinian laws of natural selection as plants and animals. Applying this to human society. 26. People on all sides of the political spectrum used Social Darwinism to support their views. For example, the American Civil War took place during Darwin’s life (it started not long after publication of the Origin of Species.). People used Darwin’s views to both support and to argue against slavery. Why? a. Argue against slavery- We all have the same ancestors. b. Support- There was a competition: the side that won should have slavery. c. Anti-Slavery argument: there exist human differences, such as skin color, for natural selection reasons – thus blacks are the same kinds of species as whites. d. Pro-Slavery argument: that blacks were (mostly) all poor and uneducated it’s because of their bad genetics. 27. Another possible implication is in favor of eugenics. What does that mean? Eugenics seeks to promote breeding in those with “good” gene and dissuade breeding in those with “bad” gene. Genetic engineering can be interpreted as eugenic. 28. Some people think that Darwin’s theory is in conflict with the Design Argument. Why? a. Design argument- god is changing things. b. Darwin- this is happening without any reference to god. c. By simply saying animals change relative to their environment & genetically, one is therefore also implying they were not designed “perfectly” by a God - otherwise they would never change in the first place! The Christians thought animals were designed by god and unchangeable. 29. There is a new version of a sort of Design Argument, called Fine Tuning. What does that mean? a. The idea that the universe produced life by pure chance on the surface seems highly unlikely. This is because so many factors must be in the right condition in order for life to possibly exist, including the properties of gravity, carbon, and water. Isf gravity were barely stronger than it is now, then intelligent life likely would not have formed according to some scientists. We have JUST the right amount and type of factors in the exact specific conditions for life. This implies the factors have been intentionally “adjusted” by an external agent (like god), in order to permit life and thus implies a God. b. The universe has order and very specific conditions for life. c. It’s highly impossible this came about randomly. Therefore, God must have “tuned” or adjusted the universe such that this could be possible.