I know that when we see red light (via electromagnetic frequencies in the red range) and blue light (via electromagnetic frequencies in the blue range) at the same time, we perceive it as magenta light.

Is it possible for non visible electromagnetic frequencies (such as ultraviolet and infrared) to combine in a way that makes us see it as a visible light?


1 Answer 1


The short answer is no we cant. Notice that the magenta you see does not really exist on its own; it's our brain filling in the gaps and mixing impulses. As for combining UV and IR I am not an expert at this field and I would gladly appreciate some exceptions to the logic I'm about to put forward. This is because the cone cells/receptors in our eyes only respond to visible light. We can see magenta because the two cones are being activated together and our brain perceives this impulse as magenta. But neither UV nor Infra-red light would stimulate the cones at least in the visual sense. Hence, there are no signals for the brain to process into any color. Thus, it seems to be that we cant combine UV and Infra-red to form visible light, at least not by just photons of those two frequencies.

A useful answer to read and support the argument: Why does adding red light with blue light give purple light?

  • $\begingroup$ intuitively it shouldn't since each "color"(an interval of electromagnetic spectrum which may or may not be visible) has its own wavelength, and as you said, our eyes aren't sensitive to frequencies too low and frequencies too high, and to my understanding, different frequencies do not interact to merge into a different frequency. Still curious if I am misunderstanding it and there is a way for different frequencies to combine into new frequencies. $\endgroup$
    – Dmytro
    Commented Aug 9, 2018 at 1:19
  • $\begingroup$ I see your concern, I agree but I do not think that there is a way at least for your eyes to detect such a mixture. And of-course I am also open to more expert opinions. Maybe a post on Biology stack exchange could yield some results too. $\endgroup$ Commented Aug 9, 2018 at 6:01

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.