Do all objects have thermal radiation? What if it's not? Under what conditions can I get it?

Everyone knows a little physics. The wavelength of light is not just what we can see with our eyes. Besides, there are many other waves around us. It's just that we can't detect them through our own sensory perception.

Infrared light is the light emitted by an object that exceeds the wavelength of the red spectrum. Almost all objects have infrared light, that is, thermal radiation, even in the vast space. According to scientists' investigation, there was still thermal radiation in space at the beginning of the cosmic explosion.

Since I said that everything in the world has thermal radiation, we can make use of this property to examine objects according to their different temperatures and understand them. Here, you can do an experiment: now close your eyes and touch the second half of the monitor along the desktop, and you will definitely feel the highest temperature, that is, its heat radiation is the strongest. If you observe it with an infrared detector, you can clearly see its general shape.

As we all know, the sight on the infrared sniper rifle can aim at each other at night. That is to say, because there is a large temperature difference between the human body temperature and the ambient temperature, it can be easily used to detect the position of people.