And conduction requires physical contact. The third and final type of energy transfer that occurs due to heat is called radiation. Radiation is the energy transfer that occurs due to the presence of electromagnetic waves, okay? These electromagnetic waves can include UV waves, radio waves, microwaves and infrared waves, and other waves as well. So all objects on Earth and in space radiate heat or radiate energy. And that's because every single object has some temperature and zero Kelvin, the absolute zero temperature, is unattainable.