What Color Is Everything When Nobody Is Looking?
By: Lenka Otap
Tags: Philosophy, Colors, Philosophy Of Mind, Philosophy Of Science, Science

“Color is the place where our brain and the universe meet.” — Paul Klee

Is the sky really blue? Is white color made up of all colors? It sure seems like it, but it only does so, because our brain makes up such properties.

You have probably learned in school, that light is an electromagnetic wave, and the wavelength of this wave will determine the color of the light if it’s in the visible spectrum. If you want to refresh this knowledge or learn more about light, including a cool mindmap of all of its properties, check out my other piece, The Science of Light, the Heartbeat of the Universe.

Here’s what you might have learned:

The distribution of electromagnetic waves with respect to frequency and wavelength, highlighting visible spectrum, source: Wikimedia.

The electromagnetic wave seems to have different properties depending on the frequency or wavelength (two sides of the same coin since the product of frequency λ and wavelength f is a constant, namely the speed of light, λf = c). Only a small part of the spectrum is visible to us. This is what we perceive as optical light, while we are not able to see microwaves or wifi.

Is there anything special about the visible part of the spectrum then? And why are all of the colors included in such a small range of wavelengths?

Colors are not real

The wavelength of the electromagnetic waves does not carry any property of color in itself. It’s only to our human senses, that light becomes optical light and colors are made up.

If you add to the definition, that the wavelength of the electromagnetic wave determines the color of light that we observe, then it’s all good. But if you want to consider the Universe as it is, without being dependent on a human observer, then it’s important to understand, that it’s not the light itself, not the wavelength of the electromagnetic spectrum, that carries a property of color.

So asking the question, “what color is the universe when nobody is looking?”, makes as little sense as asking, “if a tree falls in the forest and nobody is around, does it make a noise?”

It’s the brain of the biological human (and many other of our vertebrate cousins in the carbon- and DNA-based life), that makes up the colors. Colors are not real! At least not real-real. Not the kind of real that exists independent of us in an ontological realism, assuming that it exist. (The alternative is the ontological relativitism, where there exist no objective and independent Universe, it is only created by our observations.)

It’s only the kind of real that humans as a species can agree upon, and luckily we don’t have any other species making arguments against us. So far, so good.

How we perceive color

The electromagnet waves propagates through space from some energy source and when it interacts with matter it gets absorbed as quanta of energy, also called photons.

Light interacts with the matter that we know, but there might be other kinds of matter out there, that doesn’t interact with light, and therefore we can’t see it nor sense it in any other way through our senses (all of our five senses are in the end based on the electromagnetic force). This is what we, for now, call dark matter, but it’s outside the scope here. If you want to read more about that, check out Gravity-based life as we don’t know it.

When an electromagnetic wave reaches our eye, it might come directly from its source, such as the sun, a star, or any other radiating black-body or by a burning chemical reaction in a fire, or it might have been absorbed by other material first, and only some of it is reflected back before it reaches the retina in our eye.