# Are radio waves red? **URL:** \ **Category:** Factual Questions\ **Created:** [July 14, 2015, 2:27am UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102 "2015-07-14T02:27:38Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![protoboard](https://avatars.discourse-cdn.com/v4/letter/p/fbc32d/32.png) [@protoboard](https://boards.straightdope.com/u/protoboard)\ **Post date:** [July 14, 2015, 2:27am UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/1 "2015-07-14T02:27:38Z")
Would it be accurate to say that a radio frequency is a color that is too red to be visible to humans? Is radio simply the extreme end of infrared? ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [July 14, 2015, 2:31am UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/2 "2015-07-14T02:31:08Z")
> [@protoboard](#): > > Would it be accurate to say that a radio frequency is a color that is too red to be visible to humans? Is radio simply the extreme end of infrared? You could just as easily say that visible light is simply soft X-rays too soft to penetrate skin; what you said is true in a technical sense, perhaps, but it’s not an especially useful way to describe the frequencies involved. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [July 14, 2015, 2:33am UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/3 "2015-07-14T02:33:50Z")
[Here’s a chart](https://en.wikipedia.org/wiki/Light#/media/File:EM_spectrum.svg). They’re a color that, if we could see, we can’t currently perceive. It would be a color that we don’t currently know. If they were red, we could see them. In fact, they’re not just infrared, they’re past infrared. ETA, if we could see radio waves (and we’d probably also be able to see IR, if that was the case, but who knows), we probably wouldn’t be able to see much else. OTOH, I’d guess that if we could see radio waves the FCC have found another band to use for radio transmission. ---
**Author:** ![zombywoof](https://avatars.discourse-cdn.com/v4/letter/z/9e8a1a/32.png) [@zombywoof](https://boards.straightdope.com/u/zombywoof)\ **Post date:** [July 14, 2015, 2:51am UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/4 "2015-07-14T02:51:23Z")
I would say any light that can be described in any meaningful way as “red” is, by definition, visible. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [July 14, 2015, 1:37pm UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/5 "2015-07-14T13:37:25Z")
By the exact same logic, you could also say that radio waves are green, blue, yellow, or orange. ---
**Author:** ![Joey\_P](https://avatars.discourse-cdn.com/v4/letter/j/919ad9/32.png) [@Joey\_P](https://boards.straightdope.com/u/Joey_P)\ **Post date:** [July 14, 2015, 1:56pm UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/6 "2015-07-14T13:56:37Z")
> [@Smeghead](#): > > By the exact same logic, you could also say that radio waves are green, blue, yellow, or orange. Well, the OP was working on the logic that that radio waves are further past red side of the visible light spectrum. It would be like asking if X-rays would be Violet…if we could see them. It wasn’t totally arbitrary. ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [July 14, 2015, 2:19pm UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/7 "2015-07-14T14:19:04Z")
> [@Joey\_P](#): > > They’re a color that, if we could see, we can’t currently perceive. It would be a color that we don’t currently know. Or indeed multiple colours. If we had evolved to perceive radio waves, there’s no reason why we’d necessarily have a single radio wave “cone” and a single perceived primary colour. ---
**Author:** ![Don\_t\_Panic](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/don_t_panic/32/398_2.png) [@Don\_t\_Panic](https://boards.straightdope.com/u/Don_t_Panic)\ **Post date:** [July 14, 2015, 2:27pm UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/8 "2015-07-14T14:27:42Z")
[Redshift.](https://en.wikipedia.org/wiki/Redshift) But you all knew that already. “More red” is a common way to describe longer wavelengths, whether or not they’re in the visible part of the spectrum. So, in that sense, the answer to the OP is “yes”. But they’re not more red than red in a visible sense. I guess you could say that it’s in a sort of metaphorical sense. ---
**Author:** ![septimus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/septimus/32/410_2.png) [@septimus](https://boards.straightdope.com/u/septimus)\ **Post date:** [July 14, 2015, 3:41pm UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/9 "2015-07-14T15:41:43Z")
> [@Joey\_P](#): > > [Here’s a chart](https://en.wikipedia.org/wiki/Light#/media/File:EM_spectrum.svg). As you can see by the wavelengths, blue photons have less than twice the energy (or half the wavelength) of red photons. The distance from reddest red to violetest blue is slightly less than one “octave,” to borrow a term from acoustics. By contrast, the distance from red to FM radio is 23 octaves; add another 7 octaves to get to AM radio; and another 30 octaves to get to the longest geomagnetic pulsations. In the other direction, it’s 12 octaves from blue to medical X-rays; and another 32 octaves to the high-energy gamma rays associated with hypernovae! Altogether more than 100 octave difference between the ultra-long radio waves and the very energetic gamma rays. (My guesstimates.) Thus, while equivalent in different frames of reference, the quantitative difference between these photons is _huge_. BTW, UIAM the width of the visible spectrum in the linked image (and others) is exaggerated for clarity, appearing more than twice as wide as correct. ---
**Author:** ![Smeghead](https://avatars.discourse-cdn.com/v4/letter/s/f1d935/32.png) [@Smeghead](https://boards.straightdope.com/u/Smeghead)\ **Post date:** [July 14, 2015, 9:16pm UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/10 "2015-07-14T21:16:53Z")
> [@Joey\_P](#): > > Well, the OP was working on the logic that that radio waves are further past red side of the visible light spectrum. It would be like asking if X-rays would be Violet…if we could see them. > It wasn’t totally arbitrary. He’s saying if you start with red and head “left”, you’ll hit radio waves. Therefore radio waves are red. I’m just pointing out that you could do the same thing starting from literally any starting point, so applying the label is completely arbitrary. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 14, 2015, 10:41pm UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/11 "2015-07-14T22:41:57Z")
There is a sense in which you can say that radio waves are “very red”, but in order for that to be correct, you really need to explain what you mean, and once you have the explanation, you don’t need the concise statement any more. ---
**Author:** ![glowacks](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/glowacks/32/5548_2.png) [@glowacks](https://boards.straightdope.com/u/glowacks)\ **Post date:** [July 15, 2015, 2:46am UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/12 "2015-07-15T02:46:39Z")
They’re red in the same sense that astronomers talk about redshift, as mentioned. Redshift makes no sense as a general term unless you’re calling anything with lower energy than what you’re expecting “redder” than expected. Thus it’s a potentially useful thing to be able to say that certain photons are redder than others, as it’s a very concise way of phrasing which of them have lower energies and longer wavelengths. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [July 15, 2015, 3:31am UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/13 "2015-07-15T03:31:52Z")
> [@Smeghead](#): > > He’s saying if you start with red and head “left”, you’ll hit radio waves. Therefore radio waves are red. I’m just pointing out that you could do the same thing starting from literally any starting point, so applying the label is completely arbitrary. Sure, except that if you start at green you go through other colours as you’re moving away from green. Start at red and there are no other colours. ---
**Author:** ![Stinky\_Pete](https://avatars.discourse-cdn.com/v4/letter/s/bc79bd/32.png) [@Stinky\_Pete](https://boards.straightdope.com/u/Stinky_Pete)\ **Post date:** [July 15, 2015, 3:54am UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/14 "2015-07-15T03:54:08Z")
There are people who can see more colors than most of us. “Researchers suspect, though, that some people see even more. Living among us are people with four cones, who might experience a range of colors invisible to the rest. It’s possible these so-called tetrachromats see a hundred million colors, with each familiar hue fracturing into a hundred more subtle shades for which there are no names, no paint swatches. And because perceiving color is a personal experience, they would have no way of knowing they see far beyond what we consider the limits of human vision.” from: [http://discovermagazine.com/2012/jul-aug/06-humans-with-super-human-vision](http://discovermagazine.com/2012/jul-aug/06-humans-with-super-human-vision) Based on this even if they do see more colors, how could they explain to us what they look like? ---
**Author:** ![protoboard](https://avatars.discourse-cdn.com/v4/letter/p/fbc32d/32.png) [@protoboard](https://boards.straightdope.com/u/protoboard)\ **Post date:** [July 20, 2015, 5:14am UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/15 "2015-07-20T05:14:33Z")
> [@Joey\_P](#): > > [Here’s a chart](https://en.wikipedia.org/wiki/Light#/media/File:EM_spectrum.svg). > > They’re a color that, if we could see, we can’t currently perceive. It would be a color that we don’t currently know. If they were red, we could see them. In fact, they’re not just infrared, they’re past infrared. > > ETA, if we could see radio waves (and we’d probably also be able to see IR, if that was the case, but who knows), we probably wouldn’t be able to see much else. OTOH, I’d guess that if we could see radio waves the FCC have found another band to use for radio transmission. That leaves me with a philosophical pondering - is it possible to perceive colors we can’t even imagine? ---
**Author:** ![Mijin](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mijin/32/9369_2.png) [@Mijin](https://boards.straightdope.com/u/Mijin)\ **Post date:** [July 20, 2015, 10:26am UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/16 "2015-07-20T10:26:53Z")
> [@protoboard](#): > > That leaves me with a philosophical pondering - is it possible to perceive colors we can’t even imagine? It’s hard to parse the question because perceive and imagine mean largely the same thing (with the difference only being “imagine” implies not directly hooked up to some external stimuli). Do you mean could \ perceive colours than \ can’t imagine? If so, the answer is almost certainly yes, although it may be impossible for us to ever verify this. ---
**Author:** ![John\_DiFool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_difool/32/19543_2.png) [@John\_DiFool](https://boards.straightdope.com/u/John_DiFool)\ **Post date:** [July 20, 2015, 12:25pm UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/17 "2015-07-20T12:25:55Z")
> [@Stinky\_Pete](#): > > There are people who can see more colors than most of us. > > “Researchers suspect, though, that some people see even more. Living among us are people with four cones, who might experience a range of colors invisible to the rest. It’s possible these so-called tetrachromats see a hundred million colors, with each familiar hue fracturing into a hundred more subtle shades for which there are no names, no paint swatches. And because perceiving color is a personal experience, they would have no way of knowing they see far beyond what we consider the limits of human vision.” > > from: > > [http://discovermagazine.com/2012/jul-aug/06-humans-with-super-human-vision](http://discovermagazine.com/2012/jul-aug/06-humans-with-super-human-vision) > > Based on this even if they do see more colors, how could they explain to us what they look like? Couldn’t a type of color blindness test be given, like they do to identify people with red-green color blindness? ---
**Author:** ![John\_DiFool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_difool/32/19543_2.png) [@John\_DiFool](https://boards.straightdope.com/u/John_DiFool)\ **Post date:** [July 20, 2015, 12:28pm UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/18 "2015-07-20T12:28:58Z")
And the article describes just such a test, yes. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [July 21, 2015, 10:04pm UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/19 "2015-07-21T22:04:13Z")
You could say that radio waves are “infrared” in the sense that “infra red” means “below red”. By custom, we only call things infrared if they are within a certain range of red, and not arbitrarily far below red, but the name does just claim “below red”, which radio is. ---
**Author:** ![wguy123](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wguy123/32/3161_2.png) [@wguy123](https://boards.straightdope.com/u/wguy123)\ **Post date:** [July 22, 2015, 2:30pm UTC](https://boards.straightdope.com/t/are-radio-waves-red/725102/20 "2015-07-22T14:30:55Z")
Radiolab had an interesting show on animals seeing other colors, in particular the mantis shrimp. Looks like there have been some updates since then…I found this interesting bit: [http://phenomena.nationalgeographic.com/2014/01/23/the-mantis-shrimp-sees-like-a-satellite/](http://phenomena.nationalgeographic.com/2014/01/23/the-mantis-shrimp-sees-like-a-satellite/) [Next page](https://boards.straightdope.com/t/are-radio-waves-red/725102.md?page=2)