Originally Posted By: Bill S.
What is a scientific "fact", and how does it differ from a widely accepted idea that might be dispensed with at any time?

Try this:

Scientific facts are a tentative class of 'truth' (or widely accepted idea) verifiable by repeatable experiment/observation, and which - although they may turn out to accurately describe reality - usually prove to serve as approximate descriptions of reality, subject to modification.

A popular example of modified scientific truth/fact is the transition from Newton's 'rational mechanics' explanation of planetary motion to Einstein's General Relativity theory. The 'celestial mechanics' of Laplace and Newton provides a very accurate prediction of planetary motion, but GR correctly accounted for the precession of the perihelion of Mercury, which was "anomalous" according to Newton. GR may yet prove to be inaccurate. Scientists would no doubt welcome such a new scientific 'truth', as a landmark breakthough.

"Time is what prevents everything from happening at once" - John Wheeler