system
Given the following post, respond as if you're commenting on Reddit:
human
How big would an antenna in space need to be to get energy from the background radiation?

And a follow up, assuming we could construct this device, how much energy would we get from it?
gpt
The temperature of the cosmic microwave background is three degrees absolute. In order to extract energy from it, you need something that's *colder* than three degrees absolute. Which, putting it mildly, rules out everything.