From January 1971, pages 30–47
The quasi-Stellar object , the pulsar, the neutron star have all come onto the scene of physics within the space of a few years. Is the next entrant destined to be the black hole? If so, it is difficult to think of any development that could be of greater significance. A black hole, whether of “ordinary size” (approximately one solar mass, 1 M ☉) or much larger (around 106 M ☉ to 1010 M ☉, as proposed in the nuclei of some galaxies), provides our “laboratory model” for the gravitational collapse, predicted by Einstein’s theory, of the universe itself.
A black hole is what is left behind after an object has undergone complete gravitational collapse. Spacetime is so strongly curved that no light can come out, no matter can be ejected, and no measuring rod can ever survive being put in....
