# Church–Turing–Deutsch principle

In what sense from the  Church–Turing–Deutsch follows that it is possible to simulate with one physical system all the other physical systems?

I know that we can build logic circuits with a Toffoli billiard ball model, and therefore starting from a physical system we can construct a model that can execute computational tasks. But this is not to simulate another physical system.

I am familiar with the Deutsch phrase that states any computation is the result of an evolution of a physical system, but I get stuck on the concept that links universal computation and physical systems.

Many thanks