Einstein gravity : Gravity as a geometry Space and time are physical objects  Gravitation – Least understood interaction – Large world-wide intellectual activity –Theoretical: ART + QM, Cosmology –Experimental: Interferometers on Earth and in space  Gravitational waves – Dynamical part of gravitation, all space is filled – Very large energy, almost no interaction – Ideal information carrier, almost no scattering or attenuation – The entire universe has been transparent for GWs, all the way back to the Big Bang Motivation
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