- Historians have debated ad nauseum whether Einstein himself was aware of the Michelson-Morley experiment in 1905. Pais seems to believe that he wasn't. However, even if Einstein himself wasn't, it was very much "in the air" that no sound experiment had ever found direct evidence of the ether, and Einstein was certainly aware of that fact. Moreover, regardless of whether Einstein himself knew of Michelson and Morley, many of the prominent physicists of that era were definitely aware of it, and directly cited it. To the extent that Einstein's work on relativity was guided by concerns that we well-known among scientists of that era, he was influenced by Michelson and Morley, irrespective of whether he was directly aware of their experimental result.
- Poincare, Lorentz, Fitzgerald, and others had all worked on ways to modify physics to account for the non-observation of ether effects. The Lorentz transformations and length contraction formula had been written down, and Poincare openly pondered a possible need for modifying the laws of motion. However, everybody was positing these things as either ad hoc fixes or as mere observations on the symmetry of the Maxwell equations. Nobody prior to Einstein posed these ideas as being derivable from the equivalence of all inertial reference frames. That's Einstein's real contribution: To see that these equations that address all of the deficits in the ether model are in fact consequences of the laws of physics being the same to all observers.
- I learned about the post of privatdozent in German-language universities, which seems quite similar to the modern phenomenon of the adjunct professor. Apparently a privatdozent could teach classes and receive a very modest fee for it, but did not have the status, institutional role, salary, or research support that a professor would enjoy. Many people back then said that academic careers were only suitable for the independently wealthy. All of this has happened before and will happen again.
Sunday, September 18, 2016
Next reading project: Subtle is the Lord by Abraham Pais
I'm currently reading Subtle is the Lord: The Science and the Life of Albert Einstein by Abraham Pais. It's a biography of Einstein, heavy on scientific detail. I'm about half-way through. Some key observations:
Interesting history of the Broader Impact Criterion
In order to get a grant from the National Science Foundation, a research proposal must score well on the basis of two criteria: Intellectual merit (in a nutshell, does a panel of experts in the field think that this is a well-designed project addressing a scientifically important question?) and Broader Impact. Broader Impact is complicated and can't be summed up in a single parenthetical. Ostensibly it could cover research that will address things like environmental issues, technologies of economic significance for the US economy, and other ways in which science could benefit the US economy and society as a whole. It could also cover "research infrastructure", e.g. if somebody wanted to develop a technology that will rapidly and systematically study key properties of hundreds of fluorescent probes used in biology then that would clearly be both of immediate intellectual merit (we learn something about those fluorescent molecules) and of broader benefit to science (this tool would push countless other projects forward).
In practice, though, Broader Impact is usually about education, public outreach, and inclusion. A researcher submitting a proposal to NSF would be well-advised to incorporate some aspect of their research into a course module (preferably one that can be easily adopted by other instructors) or a presentation to grade school kids, and include some members of under-represented groups in their labs. These are fine things, things that are often worth doing. HOWEVER (you knew there was a "however" coming) in a country with lots of instructors if every instructor out there is developing course modules and trying to get everyone else to use them, well, that's more modules than we need, and the quality will be variable. Outreach is fine, but some people are better than others, and frankly the occasional dog-and-pony-show at grade schools is probably not the biggest thing that we need if we're serious about improving k-12 science education. Moreover, inclusivity in a research group is a fine thing, but even that is better addressed at the level of admissions committees than individual research groups. (Though I do acknowledge that tying it to funding for individual labs creates a bottom-up pressure that can matter.)
I've pointed out some of the drawbacks here, and other people have documented just how confusing and contradictory the implementation of this criterion can be. I do freely acknowledge its upsides, of course. What's more interesting to me, for the purposes of this blog, is not the "on the one hand...on the other hand..." stuff, but the history of it:
Anyway, in this era where we no longer worry about adversaries with world-class nuclear physicists and rocket scientists we are quite comfortable trying to bring democracy to science. One constant theme of this blog is the tension between academic excellence and democratic values. One can quite easily resolve those tensions by viewing the academically successful as simply having a place in society but not viewing academia as the path to prominence in society. It means that you'll have to make place for the middle class (and especially the lower-middle class) on their own terms, in an economy that needs them. Alternately, one can engage in self-deception and deny any tension between academic excellence and democratic values. Broader Impact is, in some sense, NSF's attempt to do that, and de Tocqueville would no doubt recognize it as such.
In practice, though, Broader Impact is usually about education, public outreach, and inclusion. A researcher submitting a proposal to NSF would be well-advised to incorporate some aspect of their research into a course module (preferably one that can be easily adopted by other instructors) or a presentation to grade school kids, and include some members of under-represented groups in their labs. These are fine things, things that are often worth doing. HOWEVER (you knew there was a "however" coming) in a country with lots of instructors if every instructor out there is developing course modules and trying to get everyone else to use them, well, that's more modules than we need, and the quality will be variable. Outreach is fine, but some people are better than others, and frankly the occasional dog-and-pony-show at grade schools is probably not the biggest thing that we need if we're serious about improving k-12 science education. Moreover, inclusivity in a research group is a fine thing, but even that is better addressed at the level of admissions committees than individual research groups. (Though I do acknowledge that tying it to funding for individual labs creates a bottom-up pressure that can matter.)
I've pointed out some of the drawbacks here, and other people have documented just how confusing and contradictory the implementation of this criterion can be. I do freely acknowledge its upsides, of course. What's more interesting to me, for the purposes of this blog, is not the "on the one hand...on the other hand..." stuff, but the history of it:
From 1981 to 1997, NSF guidelines identified four criteria for the evaluation of proposals:One could note that from the 1990's onward we no longer felt that our chief geopolitical problem involved an adversary with world-class nuclear physicists and rocket scientists. In the 1990's our chief geopolitical concern was, um, actually, nobody really knows. The 90's were a weird time. We did "humanitarian" interventions against penny ante-foes and worried about French industrial espionage. Since 2001 our chief geopolitical concern has been people whose arsenal primarily consists of improvised explosives, rifles, and box-cutter knives. Yeah, yeah, Iran and North Korea, but Iran is more of a diplomatic issue and North Korea's nuclear program is even less sophisticated than that of Mao-era China.
● Research performance competence.
● Intrinsic merit of the research.
● Utility or relevance of the research.
● Effect of the research on the infrastructure of science and engineering.
Since 1997, however, NSF has used two criteria for the review of grant proposals: one focuses on the “intellectual merit” of a proposed activity, while a second asks for evaluation of the “broader impacts” of the research.
Anyway, in this era where we no longer worry about adversaries with world-class nuclear physicists and rocket scientists we are quite comfortable trying to bring democracy to science. One constant theme of this blog is the tension between academic excellence and democratic values. One can quite easily resolve those tensions by viewing the academically successful as simply having a place in society but not viewing academia as the path to prominence in society. It means that you'll have to make place for the middle class (and especially the lower-middle class) on their own terms, in an economy that needs them. Alternately, one can engage in self-deception and deny any tension between academic excellence and democratic values. Broader Impact is, in some sense, NSF's attempt to do that, and de Tocqueville would no doubt recognize it as such.
Wednesday, September 14, 2016
Two problems with two theories
The biggest problem with a theory of rational economic behavior is not that humans are irrational (though they often are) but that rational economic incentives under-determine human behavior. Given that we have to act rationally and maximize some measure of self-interest (usually a monetary return, but not always) there are multiple ways to get there. A glance at the great variety found in human endeavors, in business models, in industrial practices, etc. should be enough to persuade one of that.
The biggest problem with technocratic approaches to education is not that students are complicated (though they are) but that even if you knew enough to optimize some measure (whether an evil standardized test or a progressive concepts inventory that looks remarkably similar to a standardized test or some more holistic measure of "critical thinking" or whatever) you would still be under-determining what you can/should do in the classroom. There would still be multiple ways to get there, and culture and values would enter into the choices.
The biggest problem with technocratic approaches to education is not that students are complicated (though they are) but that even if you knew enough to optimize some measure (whether an evil standardized test or a progressive concepts inventory that looks remarkably similar to a standardized test or some more holistic measure of "critical thinking" or whatever) you would still be under-determining what you can/should do in the classroom. There would still be multiple ways to get there, and culture and values would enter into the choices.
Tuesday, September 13, 2016
Ibn al-Haytham on refraction
I'll start with the confession: I'm not going to read all of Book 7 of the Kitab al-Manazir. Experimental papers are best read when they have the diagrams on the same pages as the main text, not when you have to flip around constantly to find diagrams and tables. Not to mention that he got a lot of stuff wrong, and according to the translator's preface he probably didn't do all of the experiments that he described. But I did want to see if he presaged the Principle of Least Time.
So I read the translator's preface. One fascinating tidbit is that Ibn al-Haytham did measurements of the effect of refraction in the atmosphere on the apparent positions of stars near the horizon. That was pretty amazing. He was able to show that the atmosphere refracts light, implying that its optical properties are different from the more distant medium separating the earth from the celestial sphere that they believed the stars inhabited. I didn't know that.
The translator mentioned a discussion of "easiest paths" at the end of chapter 2, so I read the first two chapters. I skimmed the experimental section because (as I said above) it's hard to read. I did carefully read the theoretical discussion in the last few pages, and it is definitely interesting. Ibn al-Haytham thinks of refraction as occurring because the light encounters difficulty in piercing an interface, and we know that when chopping wood it is easiest to piece the wood if the ax strikes it perpendicularly rather than at a glancing angle. He talks about breaking up motion into components perpendicular and parallel to the interface, and if the perpendicular component is small then it is difficult to pierce the interface. In Ibn al-Haytham's view, when light encounters a denser medium (higher index) light tries to incline toward an easier direction. There's a vague concept of a "path of least resistance" in here, but he doesn't actually use the word "path." Rather, he talks about the direction that is easiest to move in. That is a purely local description of the dynamics of the light (whether it's a ray or particle), based entirely on things that happen at the interface. Likewise, the rest of the discussion involves only the interfaces, components of motion at interfaces, and analogies to mechanical phenomena that involve changes in motion at interfaces. Fermat's Principle of Least Time, on the other hand, is a global principle, one that involves a consideration of the entire path that light will take from one location to another. There's no hint of a global principle here.
Also, he has a much fuzzier explanation of what happens when you go from a high-index medium to a low-index medium. There's no principle of time-reversal here.
Now, I haven't read any of Fermat's work. I don't know if he read Ibn al-Haytham. Maybe he really liked Ibn al-Haytham's idea about picking a direction that makes motion easier and then generalized it to a global principle. Maybe not. I don't know. What I do know is that there's no hint of the Principle of Least Time in Ibn al-Haytham's work, because the Principle of Least Time is (1) global rather than local and (2) based on a model of a medium-dependent speed rather than a medium-dependent resistance. The second point is less important, because I'm drawing a distinction that isn't really salient until you appreciate inertia and the fact that light doesn't have mass (not points that are required to do important things in an optics class) but still, I see none of the seeds of Fermat's work here.
Sorry to be the bearer of bad news.
DISCLAIMER: I only read a translation of the Latin text. Maybe the Arabic text has something better. However, the translator noted a number of errors in the translation from the original Arabic text to the Latin edition, and this section wasn't mentioned. Barring some additional evidence from a historian who knows medieval Arabic I consider it very unlikely that Ibn al-Haytham can be credited with the Principle of Least Time.
So I read the translator's preface. One fascinating tidbit is that Ibn al-Haytham did measurements of the effect of refraction in the atmosphere on the apparent positions of stars near the horizon. That was pretty amazing. He was able to show that the atmosphere refracts light, implying that its optical properties are different from the more distant medium separating the earth from the celestial sphere that they believed the stars inhabited. I didn't know that.
The translator mentioned a discussion of "easiest paths" at the end of chapter 2, so I read the first two chapters. I skimmed the experimental section because (as I said above) it's hard to read. I did carefully read the theoretical discussion in the last few pages, and it is definitely interesting. Ibn al-Haytham thinks of refraction as occurring because the light encounters difficulty in piercing an interface, and we know that when chopping wood it is easiest to piece the wood if the ax strikes it perpendicularly rather than at a glancing angle. He talks about breaking up motion into components perpendicular and parallel to the interface, and if the perpendicular component is small then it is difficult to pierce the interface. In Ibn al-Haytham's view, when light encounters a denser medium (higher index) light tries to incline toward an easier direction. There's a vague concept of a "path of least resistance" in here, but he doesn't actually use the word "path." Rather, he talks about the direction that is easiest to move in. That is a purely local description of the dynamics of the light (whether it's a ray or particle), based entirely on things that happen at the interface. Likewise, the rest of the discussion involves only the interfaces, components of motion at interfaces, and analogies to mechanical phenomena that involve changes in motion at interfaces. Fermat's Principle of Least Time, on the other hand, is a global principle, one that involves a consideration of the entire path that light will take from one location to another. There's no hint of a global principle here.
Also, he has a much fuzzier explanation of what happens when you go from a high-index medium to a low-index medium. There's no principle of time-reversal here.
Now, I haven't read any of Fermat's work. I don't know if he read Ibn al-Haytham. Maybe he really liked Ibn al-Haytham's idea about picking a direction that makes motion easier and then generalized it to a global principle. Maybe not. I don't know. What I do know is that there's no hint of the Principle of Least Time in Ibn al-Haytham's work, because the Principle of Least Time is (1) global rather than local and (2) based on a model of a medium-dependent speed rather than a medium-dependent resistance. The second point is less important, because I'm drawing a distinction that isn't really salient until you appreciate inertia and the fact that light doesn't have mass (not points that are required to do important things in an optics class) but still, I see none of the seeds of Fermat's work here.
Sorry to be the bearer of bad news.
DISCLAIMER: I only read a translation of the Latin text. Maybe the Arabic text has something better. However, the translator noted a number of errors in the translation from the original Arabic text to the Latin edition, and this section wasn't mentioned. Barring some additional evidence from a historian who knows medieval Arabic I consider it very unlikely that Ibn al-Haytham can be credited with the Principle of Least Time.
Sunday, September 11, 2016
A succinct take on the post-industrial economy
I figured out a way to encapsulate a lot of what frustrates me about discussions of the post-industrial economy. Everyone mouths "STEM" and "college", as though the great thing about the industrial economy was the opportunity that it provided for college-educated STEM professionals. In fact, the great thing about the industrial economy was the sort of opportunity it provided for everyone else. Yes, college-educated STEM professionals did their part in maintaining the system that provided those opportunities, but they were just one factor among many.
We've assumed that we can credential our way out of this problem, but that's insanity. We need to ask what sort of economic arrangement can provide good opportunity for those who don't have college degrees, rather than asking how to get more people through college.
We've assumed that we can credential our way out of this problem, but that's insanity. We need to ask what sort of economic arrangement can provide good opportunity for those who don't have college degrees, rather than asking how to get more people through college.
Saturday, September 10, 2016
Next book: Book 7 of De Aspectibus/Kitab-al-manazir by Alhacen/Ibn al-Haytham
My next reading will be Book 7 of the Book of Optics by Ibn al-Haytham, an Arab scientist of the 10th and 11th centuries. I read the first part of his treatise in 2009; in that part he debunks the ancient idea (going back to the much-lauded Greeks) that vision involves the emission of something from the eye. I skipped the next 5 books, which expand his theory of vision and then delve into image formation by curved mirrors. However, I recently came across an assertion that Ibn al-Haytham was the first person to discover that refraction phenomena can be derived from the Principle of Least Time, presaging Fermat's statement of the principle by more than 600 years. The Principle of Least Time is one of the most beautiful principles in physics, being closely related to the Lagrangian formulation of classical mechanics, and this coming year I am scheduled to teach optics in fall and Lagrangian mechanics in spring, so I absolutely MUST find out if the great Ibn al-Haytham has priority over Fermat in discovering the most beautiful principle in physics. If you do a Google search for "Ibn al-Haytham" and "Least Time" you will find a great many pages that assert this discovery, but so far I've found none that actually quote directly from his writings. Consequently, I'll have to read it for myself.
The matter gets complicated by the fact that Ibn al-Haytham's writings took two different forms, historically. Ibn al-Haytham did most of his work in Cairo (though he was apparently born in Iraq) and wrote it up in Arabic under the title Kitab al-Manazir (Book of Optics). However, much of his influence on the subsequent history of optics came via a Latin translation titled De Aspectibus (which, as I understand it, means roughly "On Perspective"). In the Latin translation his name was given as "Alhacen." The Latin translation is not entirely faithful to the original Arabic, which means that it is not always useful for gauging what Ibn al-Haytham actually thought. However, because of its influence the Latin translation is nonetheless worthy of study as a historical document, as a way of gauging what the Europeans did or didn't learn about optics from the Arabs. I've had trouble finding a translation of Book 7 directly from Arabic to English (it's easier to find translations of the first book, which made the vital contribution of debunking the emission theory), so I'm going to be using Prof. Mark Smith's English translation of the Latin version.
The matter gets complicated by the fact that Ibn al-Haytham's writings took two different forms, historically. Ibn al-Haytham did most of his work in Cairo (though he was apparently born in Iraq) and wrote it up in Arabic under the title Kitab al-Manazir (Book of Optics). However, much of his influence on the subsequent history of optics came via a Latin translation titled De Aspectibus (which, as I understand it, means roughly "On Perspective"). In the Latin translation his name was given as "Alhacen." The Latin translation is not entirely faithful to the original Arabic, which means that it is not always useful for gauging what Ibn al-Haytham actually thought. However, because of its influence the Latin translation is nonetheless worthy of study as a historical document, as a way of gauging what the Europeans did or didn't learn about optics from the Arabs. I've had trouble finding a translation of Book 7 directly from Arabic to English (it's easier to find translations of the first book, which made the vital contribution of debunking the emission theory), so I'm going to be using Prof. Mark Smith's English translation of the Latin version.
Wednesday, September 7, 2016
Oh, there you go, bringing class into it again
I'm not sure I agree with everything in this article from the latest American Conservative, but one needn't agree with all of it to appreciate the extra analytical dimension that it brings. Thinking about class along more dimensions than rich and poor, bringing ideology and sector into it, helps a lot.
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