if an object were to be placed in a vaccum, would light waves cease to slow down and show color?

no, they would still slow down upon entering a medium and colour is only determined by frequency(or energy, it comes to the same). frequency does not change because of the lack of an atmosphere.

"medium" meaning the object?

well, assuming it is transparent. otherwise it will just get reflected or absorbed.

if an object were to be placed in a vaccum, would light waves cease to slow down and show color?

 

Are you asking about what happens to light inside an object, if that object is in a vacuum (vs some other medium, like air or water)?

Are you asking about what happens to light inside an object, if that object is in a vacuum (vs some other medium, like air or water)?

yes

yes

 

Well the refractive index (for visible light) for air and vacuum is very similar. So not much will be different from if it was just in air.

thanks Klaynos