Lewis’ Law Sustainable computing Reversing Directions — A New Path It's imperative that we reverse course. Instead of increasing power consumption endlessly, the new path to follow decreases power consumption per unit of computation, endlessly. This is Koomey's law in reverse: "the number of joules of energy dissipated per computation halves about every two years." This will get us to the future by about 2032—the first steps having been demonstrated in the laboratory in 2020. --- https://twitter.com/MikePFrank/status/1528104243093065733?s=20&t=EYeRiDeEerLkkFFah-jweg The historical “Koomey’s Law” trend for computational energy efficiency has had efficiency improving at a rate of ~60%/yr, which is about 10x in 5 years, or 100x in a decade. BUT!! In recent years the rate has slowed to about 30%/yr, or only roughly 10x in a decade. Furthermore, we’re literally down to the very last factor of 10 (roughly) in low-level efficiency improvements for non-reversible CMOS. Minimum logic signal energies today are ~170,000 kT (~4.4 keV), and I predict they won’t get below around 20,000 kT (~0.5 keV) in practice. If developed within the next decade, reversible computing tech can help restore the rate of improvement back up towards the historical Koomey’s Law trend, as well as maintain continued improvement over a greater number of total orders of magnitude.