Empirical Science Is Observable
The scientific method requires that the scientist test a theory based on observed or predicted facts. The scientist must formulate a theory or a hypothesis based on what has been observed, then design a test by which the theory may be verified as valid or not.
If the theory produces observed events that correspond with the theory postulated in advance, then the scientist has a serious beginning point from which to claim further science (knowledge) about the specific test.
Over the last several hundred years, a number of theories have been repeated so often that they are now considered scientific laws. Scientists are confident that these laws correctly model the absolute truth of reality.
Should someone claim they have had a subjective experience that contradicts one of these laws, the burden of proof is on that person to prove that they can repeatedly demonstrate that the law is false. The standard of measure remains absolute truth about reality, verified through repeated observation.