What are the main ideas of physical science

Physical science is defined as the study of observable phenomena in the universe.The main idea of physical science is known as the "scientific method". 

This method states: 

1. observe a "real" ( not imaginary ) phenomena. 

2. make a hypothesis ( or theory / idea ) that EXPLAINS this phenomena. 

3. conduct a real experiment to test this hypothesis. 

4. confirm that the experiment validates the original hypothesis and if necessary amend the theory. 

This method is responsible for virtually every scientific explanation of every kind. It has worked so well that the very communication you are having with me is a result of the wonders of physical science. 

Hope your question was answered :)