Scientists have subjected Albert Einstein's famous theory of
gravity to its toughest real-world test so far—and it has
prevailed.  The theory, which was published nearly a century
ago, had already passed every test it was subjected to. But
scientists have been trying to pin down precisely at what point
Einstein's theory breaks down, and where an alternative
explanation would have to be devised.  Physicist Albert
Einstein. AFP/Getty Images   Einstein's framework for his theory
of gravity, for example, is incompatible with quantum theory,
which explains how nature works at an atomic and subatomic
level.  Consider that for a black hole, Einstein's theory
"predicts infinitely strong gravitational fields and density.
That's nonsensical," said Paulo Freire, an astrophysicist at the
Max Planck Institute for Radioastronomy in Germany and co-author
of the study, which appears in the journal Science.  And so
scientists are testing the general theory not because they think
it is wrong but because they are certain it can