Albert Einstein’s special theory of relativity and Quantum Electrodynamics (QED), which was formulated by Richard Feynman among others, are two important fundamentals of modern physics. In cooperation with colleagues from several international universities and institutes, a research group led by Professor Wilfried Nortershauser (Institute for Nuclear Physics at the Technische Universitat Darmstadt in Germany) re-examined these theories in experiments at the GSI Helmholtz Center for Heavy Ion Research. Even though they have been experimentally verified many times in the past and both have passed all the tests so far, these scientists wanted to explore any possible limits of the two theories.