You already get arbitrarily high upper bounds with reversible computation, and waiting until the universe gets cooler can yield 10^30x additional computation, no need for weirder physics. Bostrom mentioned both above, he was pretty explicit about the 10^85 ops cosmic endowment being a conservative lower bound. Krauss & Starkman’s 1.35e120 ops bound derived from the observed acceleration of the universe is the non-weird physics upper bound AFAIK (h/t Wei Dai).
You already get arbitrarily high upper bounds with reversible computation, and waiting until the universe gets cooler can yield 10^30x additional computation, no need for weirder physics. Bostrom mentioned both above, he was pretty explicit about the 10^85 ops cosmic endowment being a conservative lower bound. Krauss & Starkman’s 1.35e120 ops bound derived from the observed acceleration of the universe is the non-weird physics upper bound AFAIK (h/t Wei Dai).