In this work, we investigate the implications of the concept of quantum speed
limit in string field theory. We adopt a novel approach to the problem of time
on world-sheet based on Fisher information, and arrive at a minimum time for a
particle state to evolve into another particle state. This is done using both
the Mandelstam-Tamm bound and the Margolus-Levitin bound. This implies that any
interaction has to be smeared over such an interval, and any interaction in the
effective quantum field theory has to be non-local. As non-local quantum field
theories are known to be finite, it is expected that divergences should be
removed from effective quantum field theories due to the quantum speed limit of
string theory.Comment: 9 page