This all depends on the definition of "scientifically impossible" - most of these arguments were just the formal equivalent of "zomg thats impossible".
I feel there's a difference between saying "it is impossible to create a thinking machine" and "it is impossible to turn back time" or "it is impossible to create a free energy device". Perhaps even these statements will be proved wrong someday, but at least there is a noticeable difference in that we have a working example of the first statement, but the last would have implications that shift things all the way down to the smallest parts of our theories.
All in all, no discussion of whether the laws of physics permit some technological venture has much utility. The laws of physics are never wrong, whereas naysayers are wrong very often. If some conceivable path to whatever it is we want to do exists, there is no historical reason not to go ahead with it. It doesn't take more than a single counterexample to prove something possible. Perhaps the morale from history lessons such as these is to keep your mouth shut unless acknowledging the possibility of some crazy idea will create big problems for your own work. (A patent worker would have a hard time if all free energy devices were to be given scientific treatment, for instance)
I feel there's a difference between saying "it is impossible to create a thinking machine" and "it is impossible to turn back time" or "it is impossible to create a free energy device". Perhaps even these statements will be proved wrong someday, but at least there is a noticeable difference in that we have a working example of the first statement, but the last would have implications that shift things all the way down to the smallest parts of our theories.
All in all, no discussion of whether the laws of physics permit some technological venture has much utility. The laws of physics are never wrong, whereas naysayers are wrong very often. If some conceivable path to whatever it is we want to do exists, there is no historical reason not to go ahead with it. It doesn't take more than a single counterexample to prove something possible. Perhaps the morale from history lessons such as these is to keep your mouth shut unless acknowledging the possibility of some crazy idea will create big problems for your own work. (A patent worker would have a hard time if all free energy devices were to be given scientific treatment, for instance)