This project studies problems in nuclear physics. At intermediate energies heavy-ion collisions produce hot and dense matter composed of neutrons and protons, such as that expected to exist in the core of starts. This project will study those reactions using the transition state theory to produce a computer simulation that will enable a direct comparison with experimental data. At higher energies, relativistic heavy-ion collisions produce a plasma of nucleons, pions, and many other particles resembling an early state of the universe. To study this state, a good understanding of the interactions between nucleons, pions, and other particles is needed. This project will use experimental data to extract analytic expressions for the nucleon- nucleon separable potentials.