 All that could be measured was 24 attoseconds, which is the limit of the test accuracy.Again, though, other physicists believe that tunneling experiments in which particles appear to spend anomalously short times inside the barrier are in fact fully compatible with relativity, although there is disagreement about whether the explanation involves reshaping of the wave packet or other effects.Because of the strong empirical support for special relativity, any modifications to it must necessarily be quite subtle and difficult to measure.