Complex sentence: In 1887, Michelson and Morley tried to identify the state of motion of this hypothetical "preferred frame", by comparing measurements made in different directions and looking for an effect due to the Earth's orbital speed, their experiment famously produced a null result.
Split into simpler sentences: In 1887, Michelson and Morley tried to identify the state of motion of this hypothetical "preferred frame". By comparing measurements made in different directions and looking for an effect due to the Earth's orbital speed, their experiment famously produced a null result.