(2 of 2)
Mystifying Eclipses. One way to test the theory is to find a black hole. That should not be as implausible as it sounds. Scientists are already looking for binary stars* with invisible partners that may have disappeared into black holes, but are still exerting a measurable gravitational pull on the visible star. One promising-looking partner causes celestial dimouts of the star Epsilon in the constellation Auriga. These dimouts could not be due simply to a black hole passing in front of Epsilon Aurigae; the collapsar would have to be improbably large to cause that effect. But, as Cameron writes in Nature, a huge cloud of dust trapped around the black hole might act as an obscuring screen.
In any case, the black hole itself could never be observed. The only thing a dedicated scientist might do, muses Caltech Physicist Kip Thorne, long a black-hole theorist, would be to ride down the surface of a collapsing star and into a black hole. "Of course, he could never get back out, or communicate his results to the outside. But who is to deny a man the right to his own personal pursuit of knowledge?"
* A pair of stars that rotate around the same center of gravity.