Otherwise-Way-1176 t1_j6z9sqq wrote on February 2, 2023 at 11:02 PM

Reply to comment by mckulty in Do photons of different wavelengths combine to make complex wave forms? by Max-Phallus

>No. I don't think photons interact that way, creating the harmonics that distinguish a flute tone from an oboe.

What does this mean? The sound that we hear from an oboe or a flute consists of multiple frequencies added together.

You can certainly produce multiple frequencies of light and have them all arrive at your receiver - say the human eye - together. For example, light from a fluorescent light bulb and light from the sun.

>So can we form complex wave form light?

Depends what you mean by complex. Evanescent waves have an imaginary number in their propagation constant. So if by complex you mean includes complex numbers, then certainly it’s possible with light.

If by complex the OP simply means complicated, then I would argue that sunlight is already quite complicated. Unpolarized monochromatic light can be modeled as a sine wave with a slowly varying phase, which in Fourier space provides a small bandwidth around the central frequency which is very similar to FM radio, but of course the fluctuations are random so we couldn’t dig out some sort of audio signal from it.

mckulty t1_j6znp7k wrote on February 3, 2023 at 12:40 AM

> What does this mean? The sound that we hear from an oboe or a flute consists of multiple frequencies added together.

Yes, we call them harmonics, and they are the basis for octaves resulting from dividing a string into two (880hz A) or three (1320hz E) or four (1760hz A) etc parts.

So the harmonics are always higher frequency than the principal pitch, and and the first harmonic is always twice the value of the principal, eg middle C to C above middle C.

But visible light doesn't allow even the first harmonic, because 400 nm to 800 nm would make the first harmonic infrared.

So if you COULD modulate a radio wave with harmonics, which you can't, it won't create any new colors or visible whizbang.

Otherwise-Way-1176 t1_j70a0qc wrote on February 3, 2023 at 3:31 AM

I understand what harmonics are. I couldn’t figure out what point you were making.

But the original question was about radio waves, which are not visible light.

So I still don’t understand why you’re making the argument that it’s impossible to have a photon at one frequency and then another photon at 2x that frequency, just because they wouldn’t both be in the range our eyes can see.

mckulty t1_j6zov2e wrote on February 3, 2023 at 12:49 AM

> If by complex the OP simply means complicated

No he means formed, like the difference between the waveform pattern for a tuning fork (smooth sinusoidal) vs complicated like an oboe. The flute pattern below shows strong influence from the third harmonic.

https://i.imgur.com/Qp13d3Y.png

I don't know of any way to impose harmonics like that on a photon, but I'm willing to listen if someone says otherwise.

Otherwise-Way-1176 t1_j70aiag wrote on February 3, 2023 at 3:35 AM

All you have to do is allow more than one photon and it’s trivial to produce a complex waveform. Radio waves that actually arrive at an antennae in real world applications consist of more than 1 photon, so I don’t understand why you’re so attached to this idea that it has to be all packed into just one photon.

Sound waves are not carried by particles, so I don’t see why you’re insisting on this single photon restriction.

mckulty t1_j70jflh wrote on February 3, 2023 at 4:53 AM

I'm missing something but too tired to care. Of course light reinforces and cancels like any other wave.

> Sound waves are not carried by particles

Um, they don't do well in a vacuum.