I am fascinated light and how its phenomena are possible, however one particular area in which there is slight doubt in my mind is in absorbtion, after reading both online and in books 2 conflicting theories on this. The first idea is that a photon of light which has the correct amount of energy needed to make a molecule become excited into a further energy level, interacts with such a molecule and causes the molecule to become excited. After this point, if no further energy is given to the particle, it will lose energy and will no longer be excited, resulting in the electron dropping to a lower energy orbit and a photon of the same energy being reemited. Now this is all fine, but the flaw lies in the final part: if a photon of the same energy is reemitted, then surely there is no net energy gain, and therefore no absorbtion present? The second theory relies solely on wave theory and says that a particle has a particular vibratioanl frequency at which it exists and if a light wave happens to be this wavelength or a discrete multiple of it (ie. 2x it or 3x or 4x etc), then it will be absorbed and a resonance effect will take place, resulting in more vibration in the particle and therefore thermal energy, explaining why a black object gets hot in the sun. But this does not seem right to me as it bases its argument on newtonian mechanical waves rather than electromagnetic fundamentals, surely the physical vibrational frenquency cannot intertwine with E.M fields? And if this theory were true then it must say that as a particle has more thermal energy (higher frequency vibrational frequency) then it changes colour? Also, while I write this, I thought I'd pose the question, how is it possible for a substance to absorb both red and blue light, while not the colours inbetween, as blue light and red light are not linked by a discrete coefficient as suggested in theory 2? Just looking for some clarifications here as I don't want to research further into these subjects without full understanding of this seemingly illusively understood and debated principal. Thanks in advance.