Question

During his early years at the university, Newton realized that one can't just claim universal laws. The universal law must be subject to observation, rigorous ____, and mathematical proof.

Answer 1

Observation and rigorous testing.

Step-by-step explanation:

Answer 2

During his early years at the university, Newton realized that one can't just claim universal laws. The universal law must be subject to observation, rigorous TESTING, and mathematical proof.

The universal law is such that given any factors, conditions, and variable, a true discover will always remain true with zero exception and vice versa.