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To someone who is born blind, how would you best discribe what seeing is? (lemm.ee)
submitted 3 years ago by to c/asklemmy@lemmy.ml
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[–] 5 points 3 years ago (1 child)

Why would you say there's only one octave?

Human audible frequencies are in the range of 20 Hz to 20 kHz, and are logarithmic.

Human visible frequencies are in the range of 400 THz to 800 THz, and are linear.

There's far more available distinction to be made with color than with sound, it just doesn't interfere the same way.

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  • [–] 2 points 3 years ago (1 child)

    An octave is a doubling of frequency. 400 to 800 THz is one octave. Color has one octave.

    The way you know that is you don’t experience redness when absorbing ultraviolet light, and you don’t experience blueness when absorbing inferred light.

    It doesn’t “loop around” like the A note does at 440 Hz, 880 Hz, etc.

    An octave is when a doubling of frequency leads to a new waveform that stimulates the same set of neurons as the frequency an octave below it.

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  • [–] 1 point 3 years ago (1 child)

    Ah. That makes sense. Something about the harmonics, though:

    Sound generates those harmonics because it's physically vibrating sensors in our ear, so we get a 1 to 1 translation of the waveform. Light doesn't, because it's received by 4 different sensors that are sensitive at different ranges and in different phases. The reason we don't experience "blueness" in the infrared spectrum is because our infrared sensors don't know what "blue" is.

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  • [–] 1 point 3 years ago (1 child)

    You’re saying resonant frequencies don’t operate the same way with photon absorption? A molecule likely to absorb one wavelength won’t also absorb double or half that wavelength?

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  • [–] 1 point 3 years ago

    Well, think about it.

    WiFi is electromagnetic radiation, and penetrates walls. The standard frequency is 5 GHz. With harmonics, we should expect similar behavior from wavelengths that are some whole-number multiple of this frequency.

    There are multiple such frequencies within the visible light spectrum, such as 500 THz (orange), but visible light doesn't usually penetrate walls, it's instead reflected or absorbed.

    On the other end, we have X-rays, which are in the range of 3×10^(16) - 3×10^(19) Hz, which are used medically to see into the human body. There are likewise whole-number divisors, such as 200, which put a potential fundamental at around 600 THz (green). Yet, we generally can't see through people using normal light. That's why we use X-rays.

    Now, this is all well and good, but it's all purely academic, because the reason why you can't use your infrared sensors to detect the color blue or purple is because the infrared sensors aren't sensitive in that frequency, the same reason why you can't use your blue cones to detect infrared.

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