The geometrical-optics expansion reduces the problem of solving wave equations to one of the solving transport equations along rays. Here, we consider scalar, electromagnetic and gravitational waves ...

More than a month's worth of rain fell in several hours in the town of Grand Island, Nebraska, on Wednesday. Grand Island ...

Using gravitational microlensing, scientists have discovered a rare, large planet at the edge of the Milky Way. The planet is ...

On September 14, 2015, humanity crossed a cosmic threshold. LIGO detected gravitational waves - ripples in spacetime ...