Let's turn the sun into a telescope. In fact, we don't have to do any work—we just have to be in the right spot.

In the vast universe, galaxies rotate in ways that don’t make sense if only visible matter is considered. For almost a century, scientists have tried to explain this by searching for a hidden force ...

His idea: gravity can exist without any mass at all. A New Kind of Gravity The study explores a different solution to the same equations that normally describe gravity—both in Newtonian theory ...