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Talk:World History Lecture Eleven (view source)
Revision as of 19:21, May 16, 2009
, 19:21, May 16, 2009→20th century science: new section
:::::: Orwell was a member of the POUM (Workers' Party of Marxist Unification ). He wrote a book about it, ''Homage to Catalonia''. That's hardly obscure. [[User:ClementB|Clement ♗]] 16:05, 24 April 2009 (EDT)
:::::: Orwell was a member of the POUM (Workers' Party of Marxist Unification ). He wrote a book about it, ''Homage to Catalonia''. That's hardly obscure. [[User:ClementB|Clement ♗]] 16:05, 24 April 2009 (EDT)
== 20th century science ==
There are a number of comments I'd like to make about the science / technology section of this lecture. That is the only part I'm going to address; the rise of "modern physics" (quantum mechanics and relativity) happens to be something I take great interest in. Some of my comments are rather trivial, like the way Freud died, but some are, in my opinion, quite serious, to the point of being untrue, or at least seriously misleading to the point of appearing deceptive.
:But first, you have challenged other contributors making comments on the talk page for lecture 9 to take your midterm exam. Accordingly, I have created a "modern physics" midterm [[User:Robert/Physics Exam|here]]. In the spirit of good fun, I challenge you to take it. And, of course, feel free to adapt any of these questions into your exams.
Here are my comments:
*"The most notable accomplishment in science was the discovery of quantum mechanics ..." You should qualify it as "accomplishments in ''20th century'' science". I realize that this lecture is about the early 20th century, so the context should be clear, but the sentence looks funny without that qualification. Also, you should mention that there were ''two'' theoretical achievements in the early years of the 20th century: quantum mechanics and relativity. Those two together are considered to be the rise of "modern physics", perhaps the most important physics watershed in history. You may consider them very different, and you may assign much greater importance to one than the other, but the fact is that they are taken together whenever one writes the history of "modern physics".
*"ultimately produced about a dozen Nobel Prizes" About a dozen? Much more than that, I'd say. I don't have the list in front of me (it could be looked up easily), but I'd guess that most physics Nobels have been related to quantum mechanics and subatomic behavior.
*"basis for the entire computer industry today" I'll have more to say about that below.
*"Enrico Fermi, a devout Christian" I don't know for sure, but that may be a stretch. From what I've read, he was raised in a not-very-observant Catholic family, and was not very observant himself. He may have been an agnostic. But I'm not an expert on this. You could very well have better information.
*"Quantum mechanics formed the basis later for the discovery of very small transistors, which today form the integrated circuits in every computer and electronic device." More below. It is, in any case, somewhat redundant with an earlier statement.
*"relativity was proposed based on mathematical theory rather than observation" Well, quantum mechanics was also based on mathematical theory (statistical mechanics) rather than observation. No one observed quantum effects in a recognizable way until well after Planck's "quantized oscillator" theory. Of course, Planck's observations about statistical mechanics were ultimately based on observation (no area of physics can be formulated completely in a vacuum), but the same can be said of relativity -- it was based on observed invariance of Maxwell's equations, etc. The two theories actually had quite similar origins, as mathematical theories designed to explain effects that were quite esoteric in comparison with the usual way scientific theories are made (dropping balls from the Tower of Pisa, for example.)
*"the expression arose that 'space is curved.' But experiments later proved that space is flat overall." Totally misleading and/or wrong. The curvature of spacetime as the source of gravity is firmly established, and has been for decades. The way this is popularized is unfortunate, but the statement you made seems to be exploiting the imprecision of the curvature in the popular imagination. It then seems to imply that space isn't curved after all. This is just wrong, if not outright deceptive. The two effects are completely different. The scientists using supernova data to determine the overall curvature of the universe know full well that ''local'' curvature is real, and is the source of gravity.
*"Nothing useful has even been built based on the theory of relativity" More below.
*"Einstein's work had nothing to do with the development of the atom bomb, contrary to popular opinion." Largely true, and you are to be congratulated for debunking some nonsense. (I even have a book about the Manhattan Project claiming that Einstein was at Los Alamos!) But "nothing to do with" is too strong a statement. I'm not sure just how the sentence should be phrased.
*"validity of that particular award [Hulse/Taylor, I presume?] is questionable" Is this really a controversy you want to get into? Are you questioning the research or results of Hulse and Taylor? Can you cite that? Is it relevant to the history of 20th century physics?
*"Many things predicted by the theory of relativity, such as gravitons" Not true. Relativity never predicted gravitons. They arose from later attempts (still ongoing) to unify relativity with quantum mechanics. As you know, Einstein never participated in those attempts, and wasn't very accepting of quantum mechanics.
*"Many observed phenomena, such as the bending of light passing near the sun or the advance of the perihelion in the orbit of Mercury, can be also predicted by Newton's theory." '''Absolutely untrue'''. The two theories give different values for the bending of light; and the determination of which value was correct (not whether it bends at all) is what Eddington was seeking. We all know that Eddington handled the situation in a way that wouldn't pass muster today, and pointing this out was the right thing. But subsequent observations, that are accurate and unimpeachable, confirm the relativity value or 1.75 arcseconds. There is a lot of confusion in the lay literature about whether classical mechanics predicted any bending at all, and, consequently, just what Eddington was looking for. You have a chance to clear that up. But the existing article seems to muddy the waters, rather than clearing them.
:Furthermore, Newton's theory '''does not predict (anomalous) perihelion precession'''. Absolutely not at all. Now one might think that one could fudge the exponent (2) in the inverse square law, but
:*That wouldn't be Newton's theory. Newton set the exponent to 2.
:*It doesn't work in any case. The anomalous precession fraction is 3 v<sup>2</sup>/c<sup>2</sup>. Connected with the velocity as a fraction of the speed of light. It is, without question, a relativistic effect.
:General relativity is the only credible theory explaining this, and has been right from the start.
*"Eddington supposedly retorted, 'Who's the third?'" This is a very widely misunderstood anecdote. You say nothing about what he meant. Please put it into the context, so that people can understand what it was about, and not continue with their lack of understanding.
*"many seized upon the theory of relativity to apply it in a vague way to morality and social issues" Could you please say "wrongly seized upon"? I know you believe that seizing upon this is wrong; you can help put this foolishness to rest.
*"There remains enormous political support for the theory of relativity that has nothing to do with physics" Really? Does this have to do with the "vague morality and social issues" business? You seem to be implying that by putting it in the very next sentence. Do you really believe that congressional appropriations on LIGO, for example, are based on some notion that it will promote moral relativism? Can you cite evidence?
*Big bang vs. steady state -- good.
*Freud -- minor nit: Is there a point to saying that his death was assisted by a physician? If your intent is to show that doctor-assisted suicide did not originate with Dr. Kevorkian, and that it was going on at least as far back as 1939, please say so, with appropriate statistical data. As it is, one anecdote doesn't really say much. BTW, a far more telling anecdote relating to 20th century science would be the death of Max Planck's son.
=== When is technology "based on" something theoretical? ===
Some statements in the lecture, cited above, attempt to draw a clear distinction between quantum mechanics, with an apparently huge number of practical applications (including the entire computer and semiconductor industry) and relativity, with none at all. It is extremely misleading to say that quantum mechanics can be credited with producing transistor technology. So much so that a reader might come away from this lecture having been deceived into thinking that quantum mechanics is "more important" than relativity. They are both extremely important. But they are both '''theoretical''' advances. They give us insights into how the universe works. In retrospect, those insights are, of course, crucial to everything we do. Including transistors.
Consider this:
*Quantum mechanics tells us how electron orbitals work, and hence how all chemical reactions work. Without chemical reactions, we would have nothing.
*Relativity tells us how gravity works. Without gravity, we would have nothing. Relativity also tells us how electromagnetism works. This is the basis for the "electrical revolution" of the 19th and 20th centuries.
But people have known about chemical reactions (for example, fire) since long before 1900, and people have known about gravity since long before 1900. Fire, and all the inventions dependent on it, is now known to be explained by quantum mechanics. Space travel, to name one thing out of millions, depends on combustion. Do we credit quantum mechanics for that?
Similarly, without gravity, we would not be in orbit around the Sun. We would have none of the benefits of being close to a star. In fact, neither the Sun nor the Earth could have formed. Do we credit relativity for that?
Furthermore, the electric and magnetic forces are unified by relativity. Magnetism could be thought of as just a relativistic consequence of the electric force. Therefore, all electric motors and generators, for example, use relativity as the underpinnings of their operation. Do we credit relativity for that? Of course, Maxwell knew nothing about relativity when he formulated his equations. He did not know that they took the form that they did because of relativity. But the cavemen didn't know about the quantum-mechanical underpinnings of fire.
We can credit quantum mechanics, and relativity, '''after the fact''' for all these wonderful things. But most of them were developed without direct use of these theories. There are a few inventions (SQUIDS, for example) that directly, intentionally, and knowingly depend on quantum mechanics. But most use it indirectly. The semiconductor properties of Germanium and Silicon were known long before the details of the "band theory" solid-state quantum mechanics were worked out.
Putting it another way, one can fabricate a transistor without knowing the details of quantum mechanics, just as one can upload gravitational time dilation information to GPS satellites, or turn on a fan, without knowing the details of relativity.
[[User:Robert|Robert]] 15:21, 16 May 2009 (EDT)