Never, actually the process of learning stops when one start to think that everything he knows is a fact and can never be proved wrong.
WHAT SCIENTIFIC IDEA IS READY FOR RETIREMENT?
Ideas change, and the times we live in change. Perhaps the biggest change today is the rate of change. What established scientific idea is ready to be moved aside so that science can advance?
Moore's Law, in simple words, it states that the processing power, number of transistors on a dense semiconductor chip is doubled every two years. Its based on prediction by observation, not on scientific facts. Still for decades, it's been used to layout longterm plans by semiconductor industry. But it is no longer applicable as the size of a single transistor cannot be less than the limitations imposed by its manufacturing process and the actual minimum size of a single molecule that can act as diode, triode...