What color are things that are smaller than 200 nm? You can't see them in an optical microscope anymore, so they're… they have no color at all. Yet, they exist and are perfectly visible to a scanning electron microscope.
The visible light itself has just too long of a wavelength to bounce off of an object this small.
So yeah, there are truly colorless things that aren't void.

But in what color does that microscope project it and why that color?

@retoor typically, a scanning electron microscope projects in grayscale. It uses electrons instead of visible light photons, so when the ray bounces off of the surface, you only get the resulting brightness. That’s essentially grayscale

@kiki

Well, grayscale would be if you had actual photons of *every* visible wavelength mixed (since that's gray).

Things under 400 nm (which is the start of ultraviolet spectrum) do have colour, but our retinas don't have receivers for them. Some animals do, though.

Still, colours are a tricky thing.

You could ask 100 people to order a colour gradient, and you'd get 100 different results.

Even grayscale is tricky, because the way we perceive intensity is actually logarithmic, not linear. Screens do actually play math tricks on us to make us perceive it as linear by running linear RGB values to the power of (usually) 2.2. (this is the fabled gamma correction).

Also, the sun isn't yellow. It's white (and its peak of emissive power is actually green, not yellow, which is why our vision is sharpest on green wavelengths).

There is more.

Things which are transparent (like glass) have no color.

Dark matter has no color.

Black holes have no color.

And the skin of woke people has no color.

@Lensflare glass has color: just stack a lot of glass. Dark matter? Nobody have ever seen it. Black holes? They just mirror the void

@kiki @Lensflare

Glass has colour. Everything sufficiently macroscopic has a colour because it radiates photons based on temperature. It just so happens that on normal temperature ranges they emit in infrared (why incorrectly named night goggles work). If you were to heat them up enough, they'd go, go figure, *red hot*.

I'm willing to accept quarks too but only because of the *name* of quantum chromodynamic. (Doesn't really have anything to do with colour).

Dark matter, as we understand it today, can't have colour because it doesn't interact with the EM field in any known way.

(Some*) Black holes are actually the brightest objects in the universe. Sure, we can't see anything past the event horizon, but the accretion disk matter is accelerated to a significant fraction of the speed of light, which makes it glow like there's no tomorrow. Quasars (the brightest objects in the universe) are supermassive black holes really.

The skin of woke people is so thin that I think it behaves like dark matter. Photons just phase through it.

Also, for an extra brainfuck. You've heard that light from very distant astronomical entities takes millions of years to reach us, and that as you get closer and closer to the speed of light, your subjective time dilates.

Well, when you are a photon and you travel at the actual speed of light, time doesn't flow at all, so technically, as far as that photon is concerned, it arrived here at the same time it was emitted.

@CoreFusionX Penrose's conformal cyclic cosmology. If you haven‘t heard about it, there is a nice PBS spacetime episode.

In a universe without matter (as predicted by the big rip) there is no difference between a distance of 1 cm and trillions of kilometers :)
So distance and size has no meaning.