[chatmasta]

I enjoyed this lecture [0] from Scott Aaronson about closed timelike curves and the impact they would have on computational complexity theory. Basically, they would give you the ability to spend an eternity computing some subcalculation, and then return to where you started with the result in hand.

[0] https://youtube.com/watch?v=Ha4eG8gLSK4

[superposeur]

Yes it’s really interesting how the quantum information folks have managed to recast known features of classical physics (second law of thermodynamics, no closed timelike curves) as “implausible computational tasks”.