Computers are physical systems: what they can and cannot do is dictated by the laws of physics. In particular, the speed with which a physical device can process information is limited by its energy and the amount of information that it can process is limited by the number of degrees of freedom it possesses. This paper explores the physical limits of computation as determined by the speed of light $c$, the quantum scale $\hbar$ and the gravitational constant $G$. As an example, quantitative bounds are put to the computational power of an `ultimate laptop' with a mass of one kilogram confined to a volume of one liter.

A Energy point of view to define physical limit of computation from mass.

It does not require much knowledge on QM or computers, just skip the specific numbers if you are unfamiliar with them, as exact numbers are irrelevant.

I got redirected to this article from another piece - https://seirdy.one/posts/2021/01/12/password-strength/

which tries to find the sufficient amount of bits for a password to be safe - assuming we use all energy in universe