We are ridiculously far from physical limits in our current artificial computers (both theoretical [1], and practical [2]). For more technical details see Jim Keller: [3] [4] [5].
[2] The ~12 watts computer inside each living human adult skull (and perhaps each eukaryote cell [6]) is still the state-of-the-art, for quite some time.
[6] Our computers aren't yet able of polycomputation, where the computation topology, data, and functions depend on the observer, instead of computation in a passive implementation, once done forever set in s̶t̶o̶n̶e̶ silicon, 2023, Michael Levin, Agency, Attractors, & Observer-Dependent Computation in Biology & Beyond, https://www.youtube.com/watch?v=whZRH7IGAq0
Physical limits don't matter much when economic limits (transistor cost) are reached much earlier. What matters is not transistors per chip area (Moore's law) but FLOP/s per chip cost. Also FLOP per chip power draw.
Economic limits are imaginary, secondhand effects of the ideological goggles one's society decides to wear at a certain time for arbitrary reasons. USA during the Manhattan Project knew of no economic limits, i.e. they could arbitrarily push them according to the greater goal; China today, for instance, knows no economic limits. But yes, today, in the "Western" world a speech such as "we choose to get 160 zetaflops (10^21) [1] under your desk in 10 years because it is hard" [2] would be unimaginable, also because you can count on the fingers of an amputated arm how many politicians know what a FLOP is.
Interestingly enough, penny pushing also destroys capitalism, see The Man Who Broke Capitalism: How Jack Welch Gutted the Heartland and Crushed the Soul of Corporate America―and How to Undo His Legacy [1].
[1] https://en.wikipedia.org/wiki/Limits_of_computation
[2] The ~12 watts computer inside each living human adult skull (and perhaps each eukaryote cell [6]) is still the state-of-the-art, for quite some time.
[3] 2021, Jim Keller: The Secret to Moore's Law, https://www.youtube.com/watch?v=x17jIKQf9hE
[4] 2019, Jim Keller: Moore’s Law is Not Dead, https://www.youtube.com/watch?v=oIG9ztQw2Gc
[5] 2023, Change w/ Jim Keller, https://www.youtube.com/watch?v=gzgyksS5pX8
[6] Our computers aren't yet able of polycomputation, where the computation topology, data, and functions depend on the observer, instead of computation in a passive implementation, once done forever set in s̶t̶o̶n̶e̶ silicon, 2023, Michael Levin, Agency, Attractors, & Observer-Dependent Computation in Biology & Beyond, https://www.youtube.com/watch?v=whZRH7IGAq0