It is difficult for a theory to survive such a test.

The professor attempted to elucidate the complex theory.

Scientists use experiments to demonstrate their theories.

This experiment provides demonstrative evidence of the theory.

Freud's theories revolutionized the field of psychology.

The equivalence of the two theories was proven by the mathematician.

The two theories complementarily explain the phenomenon.

The theory is widely accepted in the scientific community.

The bases of this theory are still being studied.

He wrote a treatise on the theory of relativity.