Two types of science: Operational or experimental and historical or forensic. Historical science deals with origins, the unseen past, unobserved past events. Operational science deals with the present, not the past. Most people confuse or conflate these two types of science. They are not the same. The former is repeatable and the latter is not.
Most scientists themselves do not understand the distinction. They often are too close to the subject to realise.
When a forensic scientist enters a crime scene he collects evidence. These are, for example, bodily fluids, tissue samples, fingerprints, paint scrapings, etc. He goes to his lab and uses sophisticated machines to determine the DNA of the victim or perpetrator, or scan for a fingerprint match in a data base, etc. That is repeatable science, hence operational science.
