From PhilPapers forum Philosophy of Physical Science:
The Logic of Physics: Some Problematic Concepts
Reply to Hachem El Ouggouti
Mister Feynman, lend me your dreams: the False Duality of Light
http://philpapers.org/post/19414 and immediately following it,
and other posts concerning Light.]
Feynman's analysis of light in "QED" is I think very representative of the confusion between Light as a medium, and the elements of light or the photons. You never really know what the author is exactly talking about. For instance, the idea that light obeys probabilistic laws like the Quantum theorist would like us to believe, sounds quite nonsensical to me. Unless you replace "light" by "photon", and instead of considering the nature of the photon, one indicates that it is our knowledge that, because it is limited, has to be put in a statistical form. We are the ones who are never sure which path an individual photon will follow, and have therefore to seek our hail in probabilities.
How come Feynman does not see that? Well, as I argued in http://philpapers.org/post/15518, Feynman has always considered these two concepts as being equivalent. Maybe the idea of the duality of light, its double nature as wave and particle, was so ingrained, that he did not see the need to distinguish between the analysis of both aspects, making the transition from one approach to the other seem completely natural and seamless. But then, I am not a Feynman expert and will therefore not speculate any further on the reasons behind this confusion.
Let me formulate my view as clearly as possible: waves do not exist.
George: Allah Akbar! There he goes again!
You: cool! There is no spoon! Reminds of a school also.
me: you have been to school?
You (nonchalantly): nah! we are born with all the knowledge and languages of our host.
me: host? What do you mean, host? Never mind, I don't wanna know. What school?
You: a school of fish? When you see them from a distance, you don't see the individual fishes anymore, just a wave that goes in random directions. Right?
George: by Jove! You are exactly right, my excellent man!
me: by George! Your jokes are terrible, my horrible man!
You (jubilant): By the dragon, this miscreant deserves to be thrown into the fiery pit!
George (chuckling): okay, okay! I won't say anything anymore. I'll just watch you drown in those inexistent waves.
You (hesitant): uh? Me? About the waves? You don't really mean that, do you?
Of course waves exist, but only as qualia. [God, I hate this word!] We see them going up and down, and rushing to the shore, but what does the fisherman's cork do? It just goes up and down in the same place. The physicists have created their own conceptual illusions when dealing with these visual phenomena, including mathematical equations of sines and cosines and whatnot. But in the end, what is there really when we take away the idiosyncracies of our visual system?
Look for instance at this picture of an Olympic swimmer in Rio taken with a flash and high shutter speed. The waves created by the swimmer have turned into foam, even though we would never see it happening this way. The closest we get to such a phenomenon are waves reaching the shore or hitting a rocky cliff.
Imagine now that you could shrink your size, just like the Ant Man, and there you are, standing on top of a water molecule that is about to go down. The only way to move forward is to jump to the following water molecule in the trough, wait until it rises to the top, and jump again, This way, you can be moving with the wave. Would you then have the impression that you were surfing a wave, or running an obstacle race?
So, when are we seeing the "real" reality? Well, I would say each and every time we see an aspect of it. Children playing on the shore, jumping over the waves or diving right into them, are dealing with real, not illusionary waves.
I am not sure whether "to see an aspect of reality" is the right expression. I certainly do not mean by that that reality somehow changes its form according to the observer. More that the observer is only seeing what he can see.
Let me give a bad example to show what I do not mean. Putting colored glasses or even inverting glasses would change how the things look to you, but they do not change reality. If you want to go back to your everyday world, all you have to do is take the glasses off. You cannot do that with your perception organ. You cannot decide suddenly to see things differently. Even a microscope or a telescope does not change your perception, they only enhance it.
But what if you were a bat? Now, that would be interesting, and not for the reasons that Thomas Nagel presented in his famous paper of 1974. Refuting reductionism is certainly a legitimate philosophical goal, still I find the question also very interesting for the following reason. Waves probably do not exist for bats because they are a visual concept. Sure, we speak of sound waves, electromagnetic waves and all kinds of other waves, but the fundamental inspiration is and remains that of a water wave. A quick look at the trigonometric functions and their graphs would I think convince everyone of this fact. Put a blind person in a swimming pool and teach him to swim, that still would not tell him anything about waves, until you make him feel a "wavy" surface.
If I am right, then neither bats nor the Ant Man can see waves, and still, they interact (at least as far as the bats are concerned) with the same reality as ours. Animals do not need to see to survive, other perception organs can help them do that very well. So, yes, we could say that the bats and the Ant Man are experiencing other aspects of reality, as long as we emphasize that it is still one and the same reality, even though children cannot jump from one water molecule to the other, which I am sure they would love to do, I certainly would also, and the Ant Man cannot go surfing until he has regained his normal size.
So, what is the final conclusion? Waves, as visual qualia, just like colors, only have meaning for visually gifted creatures. As such they have as much reality as anything else in the world, but they cannot be taken as representing a fundamental aspect of reality as such. They are certainly fundamental to us, and the concept of wave is certainly very useful in science, but we should be careful in drawing conclusions about the ultimate laws of nature based on how our perception organs have been shaped by evolution.
The question therefore whether Light is a wave is I think void of any meaning, unless we mean by that that we can use the concept of wave, or more precisely, the wave analogy, as an analytical tool to help us understand Light.
We must though realize that what we have done is explain one visual phenomenon, light, by another, waves. Another reason to be very circumspect about the cosmological significance of our theories of light.