Ah, sorry, I might not have been clear. I was referring to what may be physically feasible, e.g. a 3D circuit in a box with inputs coming in from the top plane and outputs coming out of the bottom plane. If you have one output that depends on all N inputs and pack everything as tightly as possible, the signal would still take Ω(sqrt(N)) time to reach. From all the physically doable models of computation, I think that’s likely as good as it gets.
Oh I see, we want physically possible computers. In that case, I can get it down to log(n) with general relativity, assuming I’m allowed to set up wormholes. (This whole thing is a bit badly defined since it’s not clear what you’re allowed to prepare in advance. Any necessary setup would presumably take Ω(n) time anyways.)
Ah, sorry, I might not have been clear. I was referring to what may be physically feasible, e.g. a 3D circuit in a box with inputs coming in from the top plane and outputs coming out of the bottom plane. If you have one output that depends on all N inputs and pack everything as tightly as possible, the signal would still take Ω(sqrt(N)) time to reach. From all the physically doable models of computation, I think that’s likely as good as it gets.
Oh I see, we want physically possible computers. In that case, I can get it down to log(n) with general relativity, assuming I’m allowed to set up wormholes. (This whole thing is a bit badly defined since it’s not clear what you’re allowed to prepare in advance. Any necessary setup would presumably take Ω(n) time anyways.)