At the end of a lecture on astronomy, describing how the planets orbit the Sun, a little old lady at the back of the room ...

Albert Einstein’s famous formula established the interchangeability of mass (matter) and energy in 1905. In 1945, this equivalency was demonstrated to all with the detonation of the first atomic bomb.

Something seems to be missing from the universe, and the favored model of physics calls it “dark matter” – but despite a century of searching, it remains a no-show. A new paper proposes an alternative ...

An astrophysicist has shown that gravity may be able to exist without mass, a theory that suggests dark matter may not be necessary to explain phenomena observed in our universe. Dark matter is a ...

New findings suggest that ordinary sound has negative gravitational mass. This is an Inside Science story. (Inside Science) -- The sound of a sonic boom may produce about the same magnitude of ...