Hi there. Here is the deal. In my lab work, I've done experiments concerning on heat conduction. Now my professor had corrected my inform, and asked me a question for which I have no answer. I consulted for my work the book "heat conduction in solids" by H.S. Carslaw. The book says at the introduction: "When different parts of a body are at different temperatures heat flows from the hotter parts to the cooler. There are three distinct methods by which this transference of heat takes place: (i) Conduction, in which the heat passes through the substance of the body itself, (ii) Convection, in which heat is transferred by relative motion of portions of the heated body, and (ill) Radiation, in which heat is transferred direct between distant portions of the body by electromagnetic radiation. In liquids and gases convection and radiation are of paramount importance, but in solids convection is altogether absent and radiation usually negligible. In this book we shall consider Conduction of heat only, and usually speak of the body as solid, though in crtain circumstances the results will be valid for liquids or gases. In this chapter the general theory of conduction of heat is developed; the subsequent ohapters are devoted to special problems and methods." I've subtracted from it the bold part. And my professor asked my, why is it negligible? and I don't know how to answer this, I've been investigating, and I get to the black body, and Planck's law, it doesn't seem like the answer I'm looking for this work, it actually seems to be like a topic for an entire different work. So I don't know what to do, or how to justify this sentence. I think that it is negligible for the temperatures we've been working in the lab, but for temperatures near the fusion point the radiation would be more and more significant with increasing temperature. Perhaps you can help to understand a bit more on thermal radiation, or point me some work or book on this topic, so I can justify correctly what I said in my inform. Thats all. Bye there.