This seems like a really simple question, and perhaps it is, but I just can't work it out so I'm asking for some help! Let's say that we have a bucket of black paint. It is black, and so it absorbs pretty much all the visible light it receives (except for some on the glossy surface that is reflected back at us). It is also paint, which is fairly inert, there are no electrons swimming freely around, and it's not in a nice regular crystal structure. I suppose there must be a dye in the paint to make it black, but what is it about this dye which means it can absorb all light? It can't be just via electron level changes, because that'd only select a few distinct frequencies of light, so how does it work? My guess would be that rather than interacting with the dye and shifting electrons around, the photons might interact as you'd expect IR light to, and start the molecules vibrating. But if this is right, when do the photons decide do stop vibrating and start changing electron levels, or not interact at all? Thanks in advance!