Let me rephrase the question – Do we call the Visible Spectrum that because that’s what we can see or is there something different about that part of electromagnetic spectrum (ES) that allow vision to occur. Alternately, If light is dual in nature, being both a wave and a particle, is that the same for other parts of the ES?
Which brings me to the question that I’m most curious about; would it be possible for a creature exist that can see, the same way we see, but using frequencies from other areas of the ES?
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Visible light is just what we can see. Other animals can see other wavelength. Bees for example can see UV, and if you look at a flower through UV, you’ll be able to see patterns directing your eye to the center of the flower (where the pollen is).
I was actually listening to something on the radio the other day and apparently more animals can see in UV than can’t. Humans are a weird exception. There’s also animals that can see infrared, and some animals, like dogs, can’t distinguish between red and green.
Once you get into UV-C and above, light becomes ionizing radiation, meaning it has enough energy to knock electrons off of atoms. This is when it becomes dangerous.
Once you get down into microwaves, it because hard to distinguish the cosmic microwave background. Static on the radio is thr aftermath of the big bang.
Yes. Light is electromagnetic radiation, and not inherently different from other electromagnetic radiation in itself.
What makes visible light special is the sweet spot it occupies when it comes to interaction with matter. Most basic electronic transitions occur in the visible range, so our eyes evolved into that niche that is both accessible for biochemistry, and as well give useful information about our environment.
Our visibility also cuts off right at the infrared wavelength, beyond our vision would be blinded by thermal radiation anyway.
Visible light is just what we can see. Other animals can see other wavelength. Bees for example can see UV, and if you look at a flower through UV, you’ll be able to see patterns directing your eye to the center of the flower (where the pollen is).
I was actually listening to something on the radio the other day and apparently more animals can see in UV than can’t. Humans are a weird exception. There’s also animals that can see infrared, and some animals, like dogs, can’t distinguish between red and green.
Once you get into UV-C and above, light becomes ionizing radiation, meaning it has enough energy to knock electrons off of atoms. This is when it becomes dangerous.
Once you get down into microwaves, it because hard to distinguish the cosmic microwave background. Static on the radio is thr aftermath of the big bang.
Yes. Light is electromagnetic radiation, and not inherently different from other electromagnetic radiation in itself.
What makes visible light special is the sweet spot it occupies when it comes to interaction with matter. Most basic electronic transitions occur in the visible range, so our eyes evolved into that niche that is both accessible for biochemistry, and as well give useful information about our environment.
Our visibility also cuts off right at the infrared wavelength, beyond our vision would be blinded by thermal radiation anyway.
Yes. Light is electromagnetic radiation, and not inherently different from other electromagnetic radiation in itself.
What makes visible light special is the sweet spot it occupies when it comes to interaction with matter. Most basic electronic transitions occur in the visible range, so our eyes evolved into that niche that is both accessible for biochemistry, and as well give useful information about our environment.
Our visibility also cuts off right at the infrared wavelength, beyond our vision would be blinded by thermal radiation anyway.
>Do we call the Visible Spectrum that because that’s what we can see or is there something different about that part of electromagnetic spectrum (ES) that allow vision to occur
The former. There’s absolutely nothing special or different that separates visible light from the rest of the EM spectrum besides the fact that we can see it with our eyes. That’s why we call it visible light.
>Alternately, If light is dual in nature, being both a wave and a particle, is that the same for other parts of the ES?
This is true not just for all electromagnetic radiation but for *all* particles
>would it be possible for a creature exist that can see, the same way we see, but using frequencies from other areas of the ES?
There are already many animals that can se infrared and ultraviolet, which humans cannot.
>Do we call the Visible Spectrum that because that’s what we can see or is there something different about that part of electromagnetic spectrum (ES) that allow vision to occur
The former. There’s absolutely nothing special or different that separates visible light from the rest of the EM spectrum besides the fact that we can see it with our eyes. That’s why we call it visible light.
>Alternately, If light is dual in nature, being both a wave and a particle, is that the same for other parts of the ES?
This is true not just for all electromagnetic radiation but for *all* particles
>would it be possible for a creature exist that can see, the same way we see, but using frequencies from other areas of the ES?
There are already many animals that can se infrared and ultraviolet, which humans cannot.
>Do we call the Visible Spectrum that because that’s what we can see or is there something different about that part of electromagnetic spectrum (ES) that allow vision to occur
The former. There’s absolutely nothing special or different that separates visible light from the rest of the EM spectrum besides the fact that we can see it with our eyes. That’s why we call it visible light.
>Alternately, If light is dual in nature, being both a wave and a particle, is that the same for other parts of the ES?
This is true not just for all electromagnetic radiation but for *all* particles
>would it be possible for a creature exist that can see, the same way we see, but using frequencies from other areas of the ES?
There are already many animals that can se infrared and ultraviolet, which humans cannot.
The colour spectrum that the human eye sees is fairly well matched to the *peak* in intensity of light from the sun on earth.
This graph is a good starting point, the blue line for 5000K isn’t too far from sunlight (sunlight is nearer 6500K so shifted a little further to the left).[https://en.wikipedia.org/wiki/Black-body_radiation#/media/File:Black_body.svg](https://en.wikipedia.org/wiki/Black-body_radiation#/media/File:Black_body.svg)
The sun won’t emit any UV shorter than about 200nm (that’s about as far beyond “blue” as “red” is the other way), but the earth’s atmosphere absorbs a lot of UV so you can only go a little way into the UV (UV-B is fairly absorbed, and UV-C is essentially totally absorbed) before it effectively “goes dark”.
This picture (somewhat small) indicates the solar spectrum at the earth’s surface: [https://www.fondriest.com/environmental-measurements/wp-content/uploads/2021/01/new_par_solar-radiation-1.jpg](https://www.fondriest.com/environmental-measurements/wp-content/uploads/2021/01/new_par_solar-radiation-1.jpg)
Quite a few insects see in the near-UV, and we can use special cameras to show UV “colours” and patterns on flowers which attract insects (also why use UV light is used to attract flies into fly-zappers).
Although not as strong as visible light, there is a lot of infra-red light from the sun, extending an extremely long way in to the IR… but again a lot is absorbed by the earth’s atmosphere. For eyes based on water, the water in the eye would probably absorb many IR wavelengths, so you might need a different eye-structure.
Another thing to consider with IR is that as the wavelengths get longer the resolution decreases – specifically you can’t focus IR on a retina (or camera sensor) as finely as you can visible – so that would also have implications. Possibly bigger animals with bigger eyes might be more-able to make use of IR…?
Conversely it might be that the reason small insects see in the UV is that it will be able to focus better in their tiny eyes.
ELI5 -> Visible light is not “special” in the physics sense, as longer and shorter wavelengths still have the same basic properties. It’s mostly that what we consider the “visible” spectrum is a fair chunk of the spectrum of light that reaches the ground from the sun, so from a biological and evolutionary perspective with “natural” light, it makes sense that that’s what we “see”.
The colour spectrum that the human eye sees is fairly well matched to the *peak* in intensity of light from the sun on earth.
This graph is a good starting point, the blue line for 5000K isn’t too far from sunlight (sunlight is nearer 6500K so shifted a little further to the left).[https://en.wikipedia.org/wiki/Black-body_radiation#/media/File:Black_body.svg](https://en.wikipedia.org/wiki/Black-body_radiation#/media/File:Black_body.svg)
The sun won’t emit any UV shorter than about 200nm (that’s about as far beyond “blue” as “red” is the other way), but the earth’s atmosphere absorbs a lot of UV so you can only go a little way into the UV (UV-B is fairly absorbed, and UV-C is essentially totally absorbed) before it effectively “goes dark”.
This picture (somewhat small) indicates the solar spectrum at the earth’s surface: [https://www.fondriest.com/environmental-measurements/wp-content/uploads/2021/01/new_par_solar-radiation-1.jpg](https://www.fondriest.com/environmental-measurements/wp-content/uploads/2021/01/new_par_solar-radiation-1.jpg)
Quite a few insects see in the near-UV, and we can use special cameras to show UV “colours” and patterns on flowers which attract insects (also why use UV light is used to attract flies into fly-zappers).
Although not as strong as visible light, there is a lot of infra-red light from the sun, extending an extremely long way in to the IR… but again a lot is absorbed by the earth’s atmosphere. For eyes based on water, the water in the eye would probably absorb many IR wavelengths, so you might need a different eye-structure.
Another thing to consider with IR is that as the wavelengths get longer the resolution decreases – specifically you can’t focus IR on a retina (or camera sensor) as finely as you can visible – so that would also have implications. Possibly bigger animals with bigger eyes might be more-able to make use of IR…?
Conversely it might be that the reason small insects see in the UV is that it will be able to focus better in their tiny eyes.
ELI5 -> Visible light is not “special” in the physics sense, as longer and shorter wavelengths still have the same basic properties. It’s mostly that what we consider the “visible” spectrum is a fair chunk of the spectrum of light that reaches the ground from the sun, so from a biological and evolutionary perspective with “natural” light, it makes sense that that’s what we “see”.
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