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Post by alancalverd on May 20, 2013 7:05:46 GMT 1
Isaac Newton bought a glass prism in Cambridge market, and noted how it split white light into its constituent spectrum; thus founding the science of spectroscopy, hence electromagnetic wave propagation, relativity, and pretty much the whole of modern physics.
But if nobody had noticed the dispersive property of glass before Newton, why was anyone selling prisms?
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Post by fascinating on May 20, 2013 7:47:13 GMT 1
Presumably because they looked pretty. Same as diamonds really, they look really pretty the way they glitter, but not many know about the physics of the internal reflections. All that the people buying the prisms knew was that they got many colours from the prism, when the sun shone. Newton made the leap to the theory that the colours had already been there, bound up together in the sunlight, and the prism pulled them apart and made them visible. It's not such an obvious conclusion as we may now think.
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Post by mrsonde on May 20, 2013 12:58:53 GMT 1
Isaac Newton bought a glass prism in Cambridge market, and noted how it split white light into its constituent spectrum; thus founding the science of spectroscopy, hence electromagnetic wave propagation, relativity, and pretty much the whole of modern physics. But if nobody had noticed the dispersive property of glass before Newton, why was anyone selling prisms? The dispersive property of lenses, pinholes, and prisms was well known and widely discussed - that's why Newton bought his prism, to study the phenomenon; and that's why they were made, and were on sale in Cambridge - as scientific instruments. Newton was responding to the already well established field of optics, with very active disputes and competing theories: in particular, between Descartes, Boyle, Huygens, and Hooke. These were all aware of Grimaldi's groundbreaking observations and experiments - including with the glass prism. Your encomium to Newton is therefore somewhat misplaced - in these regards anyway. Spectroscopy and electromagnetic wave propagation - Newton held to a corpuscular theory of light, (and got the physics involved in his experiment completely wrong. In fact, he even misreported his observations, as Goethe later convincingly showed when he actually repeated the experiment - not a deliberate misreporting, of course, merely a case of seeing what he wanted to see, and overlooking aspects that didn't fit with his existing schemata - a completely typical phenomenon in any scientific experiment.) I do not see any relevance to Relativity - by which I presume you mean Lorentz and Einstein's theories. The general Principle of Relativity - applying to motion - had already been formulated by Galileo. All of these scientific fields would undoubtedly have developed along the lines they did without Newton - as they'd been developing very vigorously for decades before he started to study them ( centuries, if you go back to Grosseteste and Bacon - as Descartes certainly did.) |
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Post by mrsonde on May 20, 2013 13:15:25 GMT 1
Presumably because they looked pretty. Same as diamonds really, they look really pretty the way they glitter, but not many know about the physics of the internal reflections. All that the people buying the prisms knew was that they got many colours from the prism, when the sun shone. Newton made the leap to the theory that the colours had already been there, bound up together in the sunlight, and the prism pulled them apart and made them visible. It's not such an obvious conclusion as we may now think. Again, something of an exaggeration - that the colours were "already there" was not a new theory. What Newton did was perform an instantia crucis to settle the matter - apparently, anyway (logically, there is no such thing as a definitive experimentum crucis: they all depend on a background set of theoretical assumptions by which they're interpreted, as the history of science amply demonstrates.) From the viewpoint of the history of science, and in particular the development of physics, and the modern worldview, of far greater importance is the deeper question that Newton never really addressed - though he was acutely aware of it, from the writings of Galileo and Descartes. That is - what is the ontological status of these colours? They are not "in" the light at all, according to Galileo and Descartes, but are created in our minds. This is of course the truly revolutionary theory that had the most impact on science. The really curious thing is that physics still elides over this question. But in the meantime the Galilean view has become deeply and completely embedded - it's what alan might call an "axiom", though most people merely assume, incorrectly of course, that "science" has demonstrated and somehow proven that it's true. Thus the modern consciousness lives in a world interpreted by a metaphysical dualism - "Reality" exists but we experience nothing of it, being mathematical and totally - in principle, thanks to alan's axiom - beyond our sense apprehension, and this is the field of "scientific" (for which read: true) knowledge; and the "world" that we actually experience is entirely - in principle - the creation of our individual minds. |
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Post by alancalverd on May 20, 2013 17:56:58 GMT 1
You do have a way of making simple things complicated.
Our eyes respond to a limited spectrum of electromagnetic radiation, of sufficient energy to trigger temporary and reversible chemical reactions in the retina. We perceive a broad spectrum as "white" - interestingly, even if some bits are missing.
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Post by mrsonde on May 20, 2013 19:32:24 GMT 1
You do have a way of making simple things complicated. I'm merely correcting errors of fact. Newton didn't invent the prism, and he didn't discover or understand or help us to understand refraction, and his theories of light had nothing to do with later discoveries about electromagnetism, or spectroscopy, or relativity, or anything else really. If you don't want to be educated about these basic matters, excuse me. Others might, however; at the least, it's a useful service not to merely let them share your errors of historical fact about the matter, isn't it? Knowledge is always far more interesting, I've always found. What's that commonplace observation got to do with anything, pray tell? |
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