Physiology
Kleiber's Law
The observation that metabolic rate scales with body mass to the 3/4 power across species spanning twelve orders of magnitude in size, from bacteria to whales.
Biological Context
Kleiber's Law means larger animals are more metabolically efficient per unit mass. A mouse uses about 30 times more energy per gram than an elephant. This scaling affects lifespan, heart rate, and many other biological rates. The 3/4 exponent likely reflects the fractal geometry of distribution networks.