In this video, we explore the origin of the index of refraction, and in particular why it depends on color. As always, if you enjoy it, consider sharing it with someone else who might value the lesson as well. Coming very soon will be a follow-up answering other questions about the index of refraction that didn’t quite fit into this one.
Thanks to Grant Sanderson for another stimulating presentation.
For those who'd care to delve further, see the work of Tomonaga and of Aharonov & Bohm in re color and the index of refraction.
These matters take us into the heart of physical theory.
Newton:
"For the Rays (of light) to speak properly are not colored. In them there is nothing else than a certain Power and Disposition to stir up a Sensation of this or that Color. [...] in the Rays they are nothing but their Dispositions to propagate this or that Motion into the Sensorium, and in the Sensorium they are Sensations of those Motions under the form of Colors."
Schrödinger:
"If you ask a physicist what is his idea of yellow light, he will tell you that it is transversal electromagnetic waves of wavelength in the neighborhood of 590 millimicrons. If you ask him: But where does yellow come in? he will say: In my picture not at all, but these kinds of vibrations, when they hit the retina of a healthy eye, give the person whose eye it is the sensation of yellow."
Whitehead:
"What we see depends on light entering the eye. Furthermore we do not even perceive what enters the eye. The things transmitted are waves or — as Newton thought — minute particles, and the things seen are colors. Locke met this difficulty by a theory of primary and secondary qualities. Namely, there are some attributes of the matter which we do perceive. These are the primary qualities, and there are other things which we perceive, such as colors, which are not attributes of matter, but are perceived by us as if they were such attributes. These are the secondary qualities of matter.
Why should we perceive secondary qualities? It seems an unfortunate arrangement that we should perceive a lot of things that are not there. Yet this is what the theory of secondary qualities in fact comes to. There is now reigning in philosophy and in science an apathetic acquiescence in the conclusion that no coherent account can be given of nature as it is disclosed to us in sense-awareness, without dragging in its relation to mind."
My approach to these problems can be understood by considering Helmholtz: "Similar light produces, under like conditions, a like sensation of color."
We can both broaden and tighten his formulation and, with a nod to Heisenberg, say that the same state vector, acted upon by the same operator(s), produces the same *spectrum* of colors and sounds and so forth.
I emphasized *spectrum* just now because, as the mathematician Steen reminds us, early on in 20th-century physics, "The mathematical machinery of QM became that of spectral analysis."
Now, in a way, we've simply clarified a great many facts of everyday experience; the same things, under the same conditions, look, sound, taste, and feel the same. Then again, we've enlarged the scope of physics. Having done so, a natural question arises: How do we incorporate these additional elements of reality into the body of science?
Thanks to Grant Sanderson for another stimulating presentation.
For those who'd care to delve further, see the work of Tomonaga and of Aharonov & Bohm in re color and the index of refraction.
These matters take us into the heart of physical theory.
Newton:
"For the Rays (of light) to speak properly are not colored. In them there is nothing else than a certain Power and Disposition to stir up a Sensation of this or that Color. [...] in the Rays they are nothing but their Dispositions to propagate this or that Motion into the Sensorium, and in the Sensorium they are Sensations of those Motions under the form of Colors."
Schrödinger:
"If you ask a physicist what is his idea of yellow light, he will tell you that it is transversal electromagnetic waves of wavelength in the neighborhood of 590 millimicrons. If you ask him: But where does yellow come in? he will say: In my picture not at all, but these kinds of vibrations, when they hit the retina of a healthy eye, give the person whose eye it is the sensation of yellow."
Whitehead:
"What we see depends on light entering the eye. Furthermore we do not even perceive what enters the eye. The things transmitted are waves or — as Newton thought — minute particles, and the things seen are colors. Locke met this difficulty by a theory of primary and secondary qualities. Namely, there are some attributes of the matter which we do perceive. These are the primary qualities, and there are other things which we perceive, such as colors, which are not attributes of matter, but are perceived by us as if they were such attributes. These are the secondary qualities of matter.
Why should we perceive secondary qualities? It seems an unfortunate arrangement that we should perceive a lot of things that are not there. Yet this is what the theory of secondary qualities in fact comes to. There is now reigning in philosophy and in science an apathetic acquiescence in the conclusion that no coherent account can be given of nature as it is disclosed to us in sense-awareness, without dragging in its relation to mind."
My approach to these problems can be understood by considering Helmholtz: "Similar light produces, under like conditions, a like sensation of color."
We can both broaden and tighten his formulation and, with a nod to Heisenberg, say that the same state vector, acted upon by the same operator(s), produces the same *spectrum* of colors and sounds and so forth.
I emphasized *spectrum* just now because, as the mathematician Steen reminds us, early on in 20th-century physics, "The mathematical machinery of QM became that of spectral analysis."
Now, in a way, we've simply clarified a great many facts of everyday experience; the same things, under the same conditions, look, sound, taste, and feel the same. Then again, we've enlarged the scope of physics. Having done so, a natural question arises: How do we incorporate these additional elements of reality into the body of science?