In absence of visible light when we see any object or space to be dark (black), What is the wavelength we encounter so that the object or space looks dark to us?

  • $\begingroup$ "color" does not mean the same thing as "wavelength." Wavelength happens in the physical world. Color happens in your brain. "Black" is our name for how we perceive something that emits/reflects substantially less light than other things in our field of view. Any wavelength can look black if you put it next to something that is brighter by a few orders of magnitude. $\endgroup$ – Solomon Slow Mar 14 at 16:09

Since there is no light, there is no wavelength to be measured. 'Black' is just your brain's interpretation to the absence of signals from the receptors in your eyes.

John Rennie put it better in this question.


In black color there is not any light. The spectrum is then like that:
The human eye cannot see UV, IR... rays. If body radiates UV or IR rays, it is black.

UV rays (the body is for us black): UV

IR rays (the body is black for us):


In all graphs there is a spectrum, that is black for us.


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