
Originally Posted by
question for you
So what is it about and object that dictates a certain spectum of frequencies will not be absorbed but reflected away? Does it have something to do with the frequency of the matter?
It's complicated.
...
What's that? You want more? OK. It is related to the way the photons interact with the electrons in the material. Take a metal, for example, there is a "sea" of free electrons (which is why metals conduct electricity) this is why most metals are highly reflective.
But it is also to affected by things like crystal structure (a single crystal of salt is transparent, table salt is white), the surface texture, the available energy states of the electrons, and so on.
Take carbon, for example, this can be amorphous (no crystal structure) in which case it is black like charcoal. Or it can be in the form of graphite which has a regular structure and is shiny grey. Or it can be in a very regular crystal called diamond: this is transparent. Raw, uncut, diamnds are dull like bits of glass. Cut into facets and they sparkle like crazy.
Another example, butterfly wings can generate colours in two ways: pigments (see above) or optical effects such as interference.
In short, it is complicated.