As I have understood, as per QM, electrons could behave as waves in a double slit experiment, i.e. form dark and bright bands, albeit after sufficient electrons have been shot from the source. Also, I have come to see that gaining information about the "Which slit has the electron passed?" messes up with the original problem to the extent that gaining a certain answer about the latter (with some measuring device) would totally obstruct the interference pattern. Now my question is that is it not possible to always track a single electrons chosen path with some time keeping scheme. i.e. the time from electrons emission until its detection, and knowing its initial energy (or momentum) to some extent (as would be also revealed from the interference pattern), would reveal the "path" it has taken. Sorry for the sloppy language beforehand and thanks for your help.
I believe that any measurement which allows the determination of a particular result as a certainty alters the state of the quantum system, the electron in this case, and as a consequence will change the nature of the overall experiment so that one no longer has a "true double-slit experiment", and therefore will no longer see an interference pattern. If one is able to determine a definite path of the electron by some measurement scheme, no matter when or how, then one has altered the state of the electron and has changed the experiment.
I hope this helps.