[Potironette]

Oh wow sections of information! Thanks for taking the time to answer with all that!

So the sky is blue because the sun is mostly blue and the blue wavelengths hit nitrogen more (and nitrogen makes up most of the air) because it's a higher frequency and shorter wavelength (I was confused by "Actually, it's that higher frequencies make it less likely to have a collision, and higher frequencies mean lower wavelengths." Isn't blue light a higher frequency than red light..?).

But why is it that sometimes the sky is pink or orange? Surely both the sunlight and the nitrogen in the sky stay the same? At night is it dark blue just because there's less light?

Does the sun having more energy cause it to have lots of blue wavelengths? Similar to how the blue bit of the fire is hotter--is that even related?

Why does Newton's first law require a coordinate system to be constructed? And what does "relative rest" mean? Why does it matter that the photon doesn't rest? Or does it mean that for some reason the first law requires there to be a moving photon to be compared to a not moving photon--which doesn't happen? And since photons are always moving at c...waves of light are basically how the photons are moving?