Response from Chip Bock
- I have read (Thony Christie’s) Renaissance Mathematics for years and enjoy him, and indeed learned from him. But I’ve always been troubled by his need to disparage Galileo. I understand that rowing upstream is fun and provocative, but I think he is too hard on this guy. I’ll confess that I’m a professional particle physicist for 40 years. I work at CERN and Fermilab and indeed teach also. I know that’s supposed to dull me to the fine points of professional history and philosophy.
- For the record, I have always appreciated the role of history of science and also that of philosophy of science and even have two masters degrees as I struggled to decide whether to go into science or philosophy of science. So I’m at least sympathetic.
- And in this particular context, it’s a mistake ever to discount or downplay the intellectual courage of Johannes Kepler, especially given his crummy life. Nobody before him had ever imagined planetary motion that was not circular. The third law was indeed a prime motivation for Newton’s gravitational theory - an important part of the key that unlocked that secret.
- So with that, I’m going to say why I revere Galileo. There are four reasons:
- Mechanics. Yes, that idea of inertia was a little mixed up, I think. I believe that Galileo would have had objects moving on forever, absent a diversion, but not in a straight line. I think he would have expected them to follow the curvature of the earth. So not quite Newton’s 1st. But it’s how he got there that I think was important, and was symptomatic of many of the experiments he did. The pendulum fascinated him (I think he first enunciated its isochronism, but I could be wrong) and the return to the original spot seemed to inspire him in part to imagine rolling balls down and up inclines…then making the rolling-up incline more and more shallow in his mind, he could extrapolate to flat. A thought experiment1, right? That’s damn clever and in league with his dilution of gravity to determined that the distance increases as the square of the time, and so from the Schoolmen, to the conclusion that speed increased as the time and not the distance. He was careful and persistent in identification of experimental systematic errors. HIs explanation of projectiles is brilliant. That there might be two motions centered somehow on a single object that between them govern the two dimensional path is really clever. Of course, it followed upon careful measurement - cleverly rolling balls off table-edges at repeatable speeds by using…an inclined plane was smart, as was the rolling of balls on a large wood panel a few degrees off the ground. Stevin…sure he was smart, but pretty much only in statics. There’s other stuff in Galileo’s mechanics. He messed up the tides terribly. He came close to momentum, but not as close as even Descartes until it was solved by Huygens and Newton.
- That leads me to my second reason. I believe that Galileo was the first to attack an understanding of nature by assuming that there were regularities that are…beneath the surface… and unavailable to direct observation. The goal of terrestrial science is to reach for those uniformities and then explain actual behavior by adding a layer of deviation from the perfect situation…friction, air resistance, and so on. He never observed what he claimed was the physics…but that’s the point and that’s critical. It’s why physicists are all Platonists. I’ve never understood the problem with Koyre on this, but I know that I function as a Platonist searching for the underlying, common rules and explain deviation from those rules as imperfection - perturbations if you will. It’s the deep-down rules that matter and without that commitment, physics is impossible. I think that’s Galileo.
- The Letter to Christina. The demand that in order to dispute science that additional experiment was required and that authority is explicitly unwelcome and not appropriate is perhaps not entirely novel, but his enunciation of it and the vessel in which he inches toward the very public polishing of his originally semi-private letter I think drew the line in the sand better and more definitively than before. We owe him, in my opinion.
- His astronomy. Last, maybe in my mind, least. The most important thing he did in my opinion was make better telescopes. The hearing of it and then the subsequent, better and better construction is experimental science at its best. The priority issues are of less interest to me. Of course Harriot did similar things, but did he figure out a way to determine the heights of mountains on the moon? Of course Marius did some of the same things. Galileo, in his typically acidic way, he went after Marius on priority. But that doesn’t take away from the brilliance and the recognizably persistent search to understand something odd. That there were satellites orbiting another center of rotation was stunning. There were also Venus’ phases, the “ears” of Saturn, and of course the clever way to look at the sun (his student invented that), and the observation of the multitude of non-naked eye stars.
- The subsequent myths were always unfortunate. His ignoring of Kepler, except when he needed him, was inexcusable. This guy was problematic in many ways. Notice I never said he was the inventor of experiment or making quantitative measurements. He just did more of it and did it better and communicated it better than anyone else. Thompson was a terrible experimenter…Kaufmann was much better and got better results. But Thompson interpreted his data with inspiration of a corpuscle which is why most people don’t even know of Kaufmann. How you do things and the conclusions you draw matters.
- But the four areas above are to me recognizably scientific in a nearly modern sense and I think he uniquely put them all together in one turbulent life. So I’m impressed.
- As I started this, I have read Christie for a long time and have been meaning to ask him about Galileo and what I’ve felt is his overly tepid opinion of his influence and work and I guess seeing this article pushed me over the edge, so I guess this constitutes that communication!
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