The dynamics of mechanisms associated with basic atomic
physics processes - such as excitation, ionization, electron
transfer and pair production - that occur in collisions between
highly-charged heavy ions or photons with atoms or other ions is
investigated within a nonperturbative approach formulated in momentum space.
By directly visualizing the time evolution of the electron-positron field
around heavy ions in relativistic motion we obtain new insights and
results in the dynamics of relativistic atomic collisions.
We discuss recent nonperturbative results from numerical calculations
using massively parallel processing on the Cray-3E supercomputer of the
National Energy Research Scientific Computing Center (NERSC) in Berkeley
along with perturbative methods and recent experimental data.