Bremermann's limit
Bremermann's limit, named after Hans-Joachim Bremermann, is a theoretical limit on the maximum rate of computation that can be achieved in a self-contained system in the material universe. It is derived from Einstein's mass–energy equivalency and the Heisenberg uncertainty principle, and is c2/h ≈ 1.3563925 × 1050 bits per second per kilogram.