# Radiation of a body at 0K

Since it is necessary for a body to be above 0K in order to irradiate, I was wondering if a theorical body at 0K would be visible at all.

• A body at $0$ K will not emit anymore radiation. That's how absolute zero is defined. It's like asking if you can extract any more energy from a quantum system once it reaches the ground state. But note that it is impossible to reduce the temperature of an object to absolute zero in a finite number of steps. – Andrei Geanta Nov 5 '17 at 14:46