You can’t even experimentally verify the basic requirement for string theory to be possible: the existence of extra dimensions.
Einstein could get away with treating time as a “4th dimension”, since he was just representing it that way mathematically, not proposing that it actually was an additional spatial dimension. And he only got away with that because we can experience time, even if we have trouble explaining it, and because the math worked.
String theory can possibly claim their math works, but since we have no experience of 5th, 6th, 7th, etc, dimensions, and there is no way to verify them, it’s a dead end. At least until we mutate and develop organs that can “see” those dimensions.
“we have no experience of 5th, 6th, 7th, etc, dimensions, and there is no way to verify them, it’s a dead end. At least until we mutate and develop organs that can “see” those dimensions.”
Another way is instrumentation. We can measure a lot of stuff we cannot see or hear or smell or touch.
The numbering of dimensions may be one of the paradigms that is going to have to revisited.
Among other things higher numbers has an implicit assumption of hierarchy—which makes sense for the first, second and third dimensions but does not seem to apply to time.
Many human blind spots are caused by the inability of language to adequately describe certain things.