Einstein -

Albert Einstein | Biography, Education, Discoveries, & Facts

revealed that mass and energy are two forms of the same thing, providing the theoretical basis for both nuclear power and the atomic bomb. Einstein

He proposed that gravity is not a force between objects but the curvature of space-time caused by mass and energy. This was famously proven during a 1919 solar eclipse when astronomers observed starlight bending around the sun. Albert Einstein | Biography, Education, Discoveries, & Facts