They invoke Landauer's principle which states that irreversible computation has an intrinsic cost in terms of energy per elementary operation, namely, k T ln(2) where k is the Boltzmann constant. Assuming brute-force search, more than 2^256 elementary operations would be needed, but that would require more energy than available if one converts the whole Sun's mass into energy.
It’s worth noting several people’s answers state something to the effect of “quantum computing might be able to do it” and indeed I don’t expect an i9 or a ThreadRipper to ever defeat AES-256.
No. See https://security.stackexchange.com/questions/6141/amount-of-...
Time is not the bottleneck, energy is.
They invoke Landauer's principle which states that irreversible computation has an intrinsic cost in terms of energy per elementary operation, namely, k T ln(2) where k is the Boltzmann constant. Assuming brute-force search, more than 2^256 elementary operations would be needed, but that would require more energy than available if one converts the whole Sun's mass into energy.