# What would be the next step after quantum computing? [closed]

Is their anything that would make Quantum computing obsolete in the future? I know a Matrioksha Brain is the most powerful theoretical computer; but it probably won’t ever be realized. Too large and hard to build. I know about hypercomputing but again that seems also too far-fetched.

So let’s say quantum computing becomes mainstream. What would be the next upgrade?

• It might be wise to wait and see if quantum computers will ever be able to compute anything worthwhile except random numbers. The Google 53 qubit experiment still needs to be verified by a second party before it can be accepted as scientifically valid. – William Hird Feb 22 '20 at 19:42

I heard some time ago that if we were able to shoot a computer arbitrarly close to a black hole and retrieve it, by virtue of general relativity properties about the speeding of time near black holes we would retrieve an older computer, which would have thus computed for longer... Or alternatively we could get close to the black hole and we would see the calculations of a far away computer being made faster and faster. Note that in the first case this P and P-blackhole (the complexity class were you can shoot the computer to a black hole and retrieve it) would probably be equal, here's the reasonning. Given that in time t you can only harvest the energy contained in a sphere of size proportionnal to $$t^3$$ (we are restrained by the speed of light). Given that to get the computer $$\epsilon$$ close to the horizon of events and retrieve it you need an an energy polynomial in $$1/ \epsilon$$. Given that a computer $$\epsilon$$ close to the horizon of events experiences a speedup polynomial in $$\epsilon$$. We can deduce that P = P-blackhole.