Hartland Snyder

Hartland Sweet Snyder was an American physicist who along with Robert Oppenheimer calculated the gravitational collapse of a pressure-free sphere of dust particles as described by Einstein's general relativity, and found they contracted onto a radial distance, the Schwarzschild radius. It was later interpreted as the particles ending in the particles disappearing beneath the 'event horizon' associated with a Black Hole singularity. In recent years, it was shown by Trevor Marshall that the particle trajectories end in a shell of infinite density at the 'event horizon' radius, supporting the shell collapsar as endpoint. Snyder’s argument that the “star thus tends to close itself off from any communication with a distant observer” which is quoted as an early inference of a Black Hole, does not follow from his model. Only the very surface of the infinite density shell could reflect or emit radiation and solutions without a density singularity are needed to investigate the issue.