§32.6. THE FATE OF A MAN WHO FALLS INTO THE SINGULARITY AT R = 0
Consider the plight of an experimental astrophysicist who stands on the surface of a freely falling star as it collapses to R = 0.
As the collapse proceeds toward R = 0, the various parts of the astrophysicist's body experience different gravitational forces. His feet, which are on the surface of the star, are attracted toward the star's center by an infinitely mounting gravitational force; while his head, which is farther away, is accelerated downward by a somewhat smaller, though ever rising force. The difference between the two accelerations (tidal force) mounts higher and higher as the collapse proceeds, finally becoming infinite as R reaches zero. The astrophysicist's body, which cannot withstand such extreme forces, suffers unlimited stretching between head and foot as R drops to zero.
But this is not all. Simultaneous with this head-to-foot stretching, the astrophysicist is pulled by the gravitational field into regions of spacetime with ever-decreasing circumferential area, 4\pi r^{-2}. In order to accomplish this, tidal gravitational forces must compress the astrophysicist on all sides as they stretch him from head to foot. The circumferential compression is actually more extreme than the longitudinal stretching; so the astrophysicist, in the limit R\rightarrow0, is crushed to zero volume and indefinitely extended length.
