On the technology readiness level, I put reversible computing somewhere between von Neumann probes and warp drive. Definitely post-Singularity, likely impossible.
Irreversible is normal computing, the operation makes a state change which does not allow you to go backwards. Reversible computing is a lab curiosity at very small scale, using circuits which slide between states without dissipating energy and can slide the other way too. As Maxim says, it is far-out speculation whether we can really build computers that way.
Warp drive is more likely than not physically impossible, and even if possible would require insane energies, manipulating spacetime using exotic matter (which has never been produced) etc.
It is a true magitech.
Von Neumann Probes seem easier; they re probably physically possible but the sheer engineering for it to work seems very very difficult. In fact there are no credible plans or ideas to even build one.
Just having interstellar space travel is an immense task.
Doing thing with circuits seems comparatively more feasible.
The Landauer limit constrains irreversible computing, not computing in general.
On the technology readiness level, I put reversible computing somewhere between von Neumann probes and warp drive. Definitely post-Singularity, likely impossible.
Knowing little about irreversible computing this nevertheless sound surprising to me. Why exactly is irreversible computing so hard?
EDIT ofc I meant reversible not irreversible computing here!
Irreversible is normal computing, the operation makes a state change which does not allow you to go backwards. Reversible computing is a lab curiosity at very small scale, using circuits which slide between states without dissipating energy and can slide the other way too. As Maxim says, it is far-out speculation whether we can really build computers that way.
Warp drive is more likely than not physically impossible, and even if possible would require insane energies, manipulating spacetime using exotic matter (which has never been produced) etc. It is a true magitech.
Von Neumann Probes seem easier; they re probably physically possible but the sheer engineering for it to work seems very very difficult. In fact there are no credible plans or ideas to even build one. Just having interstellar space travel is an immense task.
Doing thing with circuits seems comparatively more feasible.
Agreed. I had [this recent paper](https://ieeexplore.ieee.org/abstract/document/9325353) in mind when I raised the question.