If you were to imagine a description of nature whose constituents are so bizarre that even its originator refuses to allow for their actual manifestation, you would not have to go past the theory of general relativity. Created almost a century ago, it was perhaps the most anticipatory advancement in the history of physics. Its development was so visionary that none of the four significant tests applied to it since – two of which were adjudged to be of Nobel quality – have truly exposed the core of this remarkable theory, where the most abstruse distortions to the fabric of space and time are imprinted.

Einstein suspended his belief at the thought of a universe that would permit singularities to form, in which matter collapses inexorably to a point and becomes forever entombed. Yet this was the boldest consequence of his new description of gravity.

Remarkably, the idea that a gravitational field ought to bend the path of light so severely that the heaviest stars should then be dark was actually forged much earlier, in the context of Newtonian mechanics, toward the end of the eighteenth century. The Reverend John Michell argued in a paper published by the Philosophical Transactions of the Royal Society that, if a star was sufficiently massive, its escape velocity would have a magnitude exceeding even the speed of light, which, being comprised of particles, would then slow down and fall back to the surface.