Alright then, please give me three examples of scientific theories that have been demonstrably proven. Should be easy, if scientific theories really are proven, as you insist. Why do you stall?
The theory that heavier-than-air powered flight is possible has been demonstrably proven. At least one mathematical proof that it was not possible had previously been offered (Simon Newcomb). Asked to comment, Orville Wright said something like 'our proof seems to fly better than the good doctor's...'
The theory that the Earth is round has been demonstrably proven. That one was no more than a theory 550 years ago.
The theory that the mechanism of a repeating rifle could be operated by the exhaust gas of the rifle itself has been demonstrably proven.
The theorems of mathematics are all rigidly proven....
The theorems of mathematics are all rigidly proven....
I fully agree that proof is possible in mathematics. Mathematics deals with formal systems. Natural science deals with nature. Demonstrative proof is possible in the former case because we know the rules that govern the system in advance. In the case of nature we do not know all the rules. (Indeed a purpose of science is to discover those rules.) This is one of the reasons that scientific propositions can never be proven.