  On the scale of nanometer to femtometer, there have several puzzles,
including neutron lifetime, proton charge radius, and deep Dirac level, etc.
With the development of high-intensity laser technologies, lasers today can
induce extremely strong electromagnetic (EM) fields. Electrons in deep shells
of atoms, as well as the atomic nucleus themself, can be affected by the laser
EM fields. This may provide a new experimental platform for studies the
physical processes on the femto-to-nanometer scale, where atomic physics and
nuclear physics coexist. In this paper, we review possible new opportunities
for studying the puzzles on femto-to-nanometer scale with high-intensity
lasers.
