Title: "Testing Lorentz Invariance with High-Precision Experiments"

The principle of Lorentz Invariance, including the isotropy of space, is an experimentally established fact and a foundation of the currently accepted theories of the fundamental forces. In the framework of the search for a fudamental unified theory of all forces, this principle is nevertheless under intense scrutiny: numerous new experiments and astronomical observations have been performed world-wide to explore whether this principle is perhaps only approximately valid. In this talk I will give an overview of the concept and theories on Lorentz Invariance and describe the recent results of our high-precision Michelson-Morley experiment testing the isotropy of space. [1] C. Eisele et al., Phys. Rev. Lett. 103, 090401 (2009)