Albert Einstein Describes Space and Time . ... Explanation: Albert Einstein (1879-1955) is considered by many the greatest astrophysicist. ... Einstein 's many visionary scientific contributions include the equivalence of mass and energy (E=mc^2), how the maximum speed limit of light affects measurements of time and space ( special relativity ), and a more accurate theory of gravity based on simple geometric concepts ( general relativity ). ... NASA Web Site Statements, Warnings, and Disclaimers . ...