The JWT is a perfectly good example of this, it's not hot compared to the sun but it's way hotter than the cosmic background. And that's if you're just reflecti

The JWT is a perfectly good example of this, it's not hot compared to the sun but it's way hotter than the cosmic background. And that's if you're just reflecting light back to the sun, when you try to extract meaningful work from it you'll have to absorb a lot more energy.