Synesthesia
For eons, people have enjoyed mapping the musical scale to the color spectrum.
Despite knowing that music is waves in air and light is waves in electromagnetic fields, I decided to do a little research and math.
The color spectrum ranges from 384 to 769THz (terahertz)
By repeatedly doubling a note (say A, at 440Hz) we can find where it would actually fall in the electromagnetic spectrum.
In the case of A, we can find its relevant note many octaves (40 octaves, 240, or 1,099,511,627,776) up at 483,785,116,221,440 (~484THz) which puts it at the redder side of orange.
You can get comparable results by multiplying the original frequency by 1.1 to get it in terahertz.
| note | midi note | frequency in center of audible, euphonious range | frequency in visible section of electromagnetic spectrum | color |
|---|---|---|---|---|
| F | 65 | 349.23Hz | 384THz | infra-red/red |
| Gb | 66 | 369.99Hz | 407THz | red |
| G | 67 | 392.00Hz | 431THz | red |
| Ab | 68 | 415.30Hz | 457THz | red |
| A | 69 | 440.00Hz | 484THz | red/orange |
| Bb | 70 | 466.16Hz | 512THz | yellow |
| B | 71 | 493.88Hz | 543THz | green |
| C | 72 | 523.25Hz | 575THz | green |
| Db | 73 | 554.37Hz | 610THz | green/blue |
| D | 74 | 587.33Hz | 646THz | blue |
| Eb | 75 | 622.25Hz | 684THz | violet |
| E | 76 | 659.26Hz | 725THz | deeper violet |
| F | 77 | 698.46Hz | 768THz | violet/ultra-violet |
The abundance of red and green in the chart has to do with the fact that our eyes are most sensitive to those two colors, not because of any bias on the part of the spectrum.
Color is, of course, entirely subjective.
These are the numbers that, when multiplied by 240 (ie are transposed up by 40 octaves) map onto the spectrum of visible light.
Other notes, such as middle C would need a different multiplier, in this case, 2^41.
Douglas Adams' number, 42, would be the exponent of the multiplier for the octave below middle C.
Maybe that's what he meant by saying that 42 was the answer to the question of the universe.
The above is based on standard tuning. Other tunings wouldn't make much difference.
When multiplying by 1.1 trillion, small differences get magnified, but not enough to matter here.
F is an interesting note in that it happens to match exactly with the upper and lower ranges of frequencies of visible light.
That could be a coincidence, but I wouldn't be surprised if our brains use some sort of hardwired math that results in the spectrum of sound and color having the same bounds, albeit separated by many orders of magnitude.
Either way, F really should be the start and end of the scale, not C. And I suppose D is the bluest note of them all.
Frankly, I'm amazed that the color spectrum maps onto the music scale so perfectly. I was expecting all the notes to map out between yellow and green, or perhaps all the colors to map out to the range between F and A#.