Hi all, I've got two questions about the emissions spectrum from solids. Question #1: I feel like I have a reasonable understanding of line absorption and emission spectrum of low density gases based on transitions of electrons between discrete allowed energy levels in a gas. I'm trying to understand the production of a continuum emission spectrum from a hot solid. I understand that a key difference between the two cases is that the quantum mechanical effects of many atoms in close proximity to one another is to split electron energy levels and in solids energy levels can form bands where the spacing between energy levels is so close that the energy levels in practice form essentially a continuum. Is it still valid to think about the emission spectrum of a solid as essentially resulting from electrons dropping from higher to lower energy levels, as they would in a gas, just with essentially a continuous set of energy transitions open to the electron? Is this a reasonably correct model, or am I missing something fundamental here. Question #2 Often when the continuum spectrum of solids is introduced in textbooks, the next step is to introduce the blackbody spectrum. I understand that blackbodies are theoretical objects which we can only approximate in practice and that the blackbody spectrum is only strictly valid under these ideal theoretical conditions. Yet, I also know that the spectrum of many solids is often approximated by the blackbody spectrum (or a blackbody spectrum modified by including an emissivity factor). I'm wondering under what conditions it's valid to treat the spectrum of a solid as if it behaved like a blackbody. It seems like something that's done fairly frequently in practice (e.g. infrared thermometers, for example, seem to implicitely assume that blackbody-type radiation flux-temperature relations can apply to real world objects). Any insight would be greatly appreciated. Alex.