Bekenstein limits, (quantum) information theory and physics, statistical mechanics…

Scott Aaronson, Your yearly dose of is-the-universe-a-simulation:

[…] to whatever extent we believe the Bekenstein bound […] we believe that in quantum gravity, any bounded physical system (with a short-wavelength cutoff, yada yada) lives in a Hilbert space of a finite number of qubits, perhaps \(~10^69\) qubits per square meter of surface area. And as a corollary, if the cosmological constant is indeed constant (so that galaxies more than ~20 billion light years away are receding from us faster than light), then our entire observable universe can be described as a system of \(~10^122\) qubits. The qubits would in some sense be the fundamental reality, from which Lorentz-invariant spacetime and all the rest would need to be recovered as low-energy effective descriptions. […] this would mean that our observable universe could be simulated by a quantum computer—or even for that matter by a classical computer, to high precision, using a mere \(~2^{10^122}\) time steps.

Huh. Well, that was cooler than I thought.