Relationship between body temperature and emitted electromagnetic radiation?

Question

Physics

The following topic prompted me to this question: habrahabr.ru/post/193142/
I am not a physicist at all, but physics is interesting to me. I tried researching this question but still can't figure it out.
Suppose we have a body at absolute zero, it does not emit any electromagnetic radiation (EI). As soon as we heat it up a little, EM will appear, but not in the visible spectrum, but with a large long wavelength, in fact, radio emission? (this is just a guess). Heating it to a certain temperature, we get the visible spectrum that our eye sees. Heating it even more, we get, for example, x-rays. Then it turns out that when an x-ray is taken, something heats up there, to high temperatures? Or is it all just about absolutely black bodies?
I apologize if I wrote complete nonsense. If someone knows the answer, enlighten or tell me what to read.

Answer 1

Everything is simple. All substances are made up of atoms, and complex substances are made up of molecules. They have a structure and besides, they interact with each other. Moreover, both have a charge and a magnetic moment. Temperature in one of its definitions is a measure of entropy, in Russian, a measure of disorder, and even more simply, an abstract assessment of the movement of components in a system. As you know, the vibration of a molecule, or a crystal lattice, which has a charge, generates electromagnetic radiation. Accordingly, the more frequent the oscillations, the greater the frequency, the shorter the length, the shorter the period.
This is what radiation is, and the wavelength (radio emission, terahertz radiation, infrared radiation, visible light, ultraviolet, X-ray radiation, gamma radiation, in ascending order of frequency) depend on temperature.
When an x-ray is taken, it is not necessary to heat the body to plasma. You can accelerate something strongly (usually electrons) and stop them abruptly. Then they will give energy into radiation.
The body is made up of different substances. some radiations pass well, others poorly, but other types of radiation can do the opposite. Because of that, the picture is obtained on the screen. X-ray radiation will be partially absorbed (including the destruction of DNA in cells, but the correction mechanisms will cope with it), partially pass through (depending on the concentration of various substances in a given area, which depend on the type of cells and their functional state), partially will be reflected. Absorbed radiation can be partially re-emitted immediately, and the rest will turn into heat. But in view of the short duration and smallness (on modern devices. And then I felt for myself how irradiation affects Soviet devices), it is almost harmless to the body.
A black body is a body that absorbs any radiation and does not reflect any (but it can radiate).
In addition, there is also a spectrum. When an electron in an orbital jumps to a lower orbital. he radiates.

Answer 2

You are confusing cause with effect. The fact that a heated body emits EM radiation is a special case. Heating leads to the appearance of radiation, but this does not mean that ONLY heated bodies can radiate.

Answer 3

If you are interested in physics, then there is a very understandable book-Ivanov. The laws of physics. Here is a link to it

Answer 4

en.wikipedia.org/wiki/%D0%A4%D0%BE%D1%80%D0%BC%D1%83%D0%BB%D0%B0_%D0%9F%D0%BB%D0%B0%D0 %BD%D0%BA%D0%B0
This formula describes thermal radiation.