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Quantum computers might be able to perform simulations which will be indistinguishable from reality. Many theories can be tested that way once we have a suffici

Quantum computers might be able to perform simulations which will be indistinguishable from reality. Many theories can be tested that way once we have a sufficiently powerful quantum computer.

jessriedel 7y ago
You can't test string theory with a quantum computer.
krastanov 7y ago
While I agree on the promise of quantum computing, the way you phrased it is somewhat misleading (hides plenty of complications (even theoretical ones) under the rug). Moreover, even if we can simulate a theory efficiently, we can not use that simulation to learn the value of a (hyper)parameter, without being able to make an observation. And this is the main problem: it is infeasible to make observations in the parameter regime of interest. The difficulty of simulating the theory is borderline inconsequential in this case.
- raspasov 7y ago
  Is observing a parameter not allowed by quantum mechanics or a current fundamental law? I am aware of the difficulty involved but an optimistic view is that anything is possible until fundamentally proven otherwise. As far as I’m aware, quantum computers would be able to simulate an entire universe in theory. Sorry if my initials comment seemed to disregard the enormity of the problem. I realize we might be decades/centuries before any of this is testable. Not unlike how Newton was compared to our current understanding of physics.
  - krastanov 7y ago
    The parameter regime of interest is monumentally out of reach to experiments. We can already derive things on paper about that regime, and with better computers we would indeed be able to make more complicated calculations about that regime. But to get something useful we also need to "fit" these calculations to observations. We do not have observations not because of a fundamental constraint, rather because it is engineeringly impossible to reach these energy scales with anything we can imagine. So the roadblock is experimental and a quantum computer would not be particularly helpful with it.

Quantum computers might be able to perform simulations which will be indistinguishable from reality. Many theories can be tested that way once we have a sufficiently powerful quantum computer.

jessriedel 7y ago

You can't test string theory with a quantum computer.

krastanov 7y ago

While I agree on the promise of quantum computing, the way you phrased it is somewhat misleading (hides plenty of complications (even theoretical ones) under the rug). Moreover, even if we can simulate a theory efficiently, we can not use that simulation to learn the value of a (hyper)parameter, without being able to make an observation. And this is the main problem: it is infeasible to make observations in the parameter regime of interest. The difficulty of simulating the theory is borderline inconsequential in this case.

raspasov 7y ago
Is observing a parameter not allowed by quantum mechanics or a current fundamental law? I am aware of the difficulty involved but an optimistic view is that anything is possible until fundamentally proven otherwise. As far as I’m aware, quantum computers would be able to simulate an entire universe in theory. Sorry if my initials comment seemed to disregard the enormity of the problem. I realize we might be decades/centuries before any of this is testable. Not unlike how Newton was compared to our current understanding of physics.
- krastanov 7y ago
  The parameter regime of interest is monumentally out of reach to experiments. We can already derive things on paper about that regime, and with better computers we would indeed be able to make more complicated calculations about that regime. But to get something useful we also need to "fit" these calculations to observations. We do not have observations not because of a fundamental constraint, rather because it is engineeringly impossible to reach these energy scales with anything we can imagine. So the roadblock is experimental and a quantum computer would not be particularly helpful with it.