Massimo Caliman
by Massimo Caliman
~1 min read


  • English


  • Theoretical Computer Science


  • Computer Science

The following argument, due to L.J. Stockmeyer, is purely physical but clearly shows what is meant by the limits of the calculable:

The most powerful computer that can be built can never be bigger than the universe (less than 100 billion light years in diameter), nor can it be made up of elements smaller than smaller than a proton (10^-13 cm in diameter), nor can it transmit information at a speed faster than the speed of light (300,000 km/s). So such a computer could have no more than 10^126 components.

A.R. Meyer and L.J. Stockmeyer have shown that such a calculator would take at least 20 billion years to solve problems whose problems whose solvability is known in principle.

Apparently, the universe is not older than 20 billion years.