You’re sorta talking here about extracting work from an initial pressure differential by converting it to a temperature differential, just like in the Planet X example.
That would be fine, but it contradicts your post, where you specifically state that everything starts in thermal equilibrium at 5K. The CMB is still irrelevant and unneeded, and does not provide the kind of T gradient you’re claiming. (6) does not work, and (7) is not true.
You’re sorta talking here about extracting work from an initial pressure differential by converting it to a temperature differential, just like in the Planet X example.
That would be fine, but it contradicts your post, where you specifically state that everything starts in thermal equilibrium at 5K. The CMB is still irrelevant and unneeded, and does not provide the kind of T gradient you’re claiming. (6) does not work, and (7) is not true.