Everything in science needs to be rethought. The difference between rethinking Einstein and rethinking Joe Schmoe's Napkin Hypothesis is that you're less likely to end up disagreeing with Einstein. It COULD happen, though.
Newton's stuff worked perfectly to the accuracies, and speeds involved...Einstein's didn't invalidate Newton's stuff, and for speeds approximating zero (compared to C), we don't use Einstein much in engineering.
It's possible that his work will later be found to be a subset of a bigger set of theories...
Originally Posted By: spock1
What about gravity waves and tachyons?
For the first, ensure you're not using the name of a recognized principle and applying it to something else. For the latter, hypothetical constructs only have hypothetical speeds.