A Brief History of Black Holes

Early in the twentieth century, the German-born theoretical physicist, Albert Einstein, published his now famous formula: E=mc². Basically, the tried-and-true formula means that the faster something moves, the heavier it gets. This formula came to be known as the mass-energy equivalence; and, as such, astrophysicists today study the ways in which matter and energy interact. An example of one of the most interesting ways in which matter and energy are able to interact can be found in black holes—an actual prediction of Einstein’s theory of relativity. “A black hole is a spacetime region where the gravitational field is so strong that no information carrying objects and signals can escape it”.¹ Black holes are a significant source of intrigue for scientists today, and it appears that much can be learned from these mind-boggling celestial phenomena.

The history of the black hole as a concept actually extends back much further than Einstein. Seventeenth-century polymath, Sir Isaac Newton, had worked out a revolutionary theory of gravitation, which stood as the cosmological scientific paradigm for over two hundred years. As such, 18th-century astronomer and scholar, P. S. de Laplace, derived from Newton’s mechanics a hypothetical object whose gravitational field would be too strong for even light to escape its grasp. Prior still to Laplace, in 1784, the English natural philosopher, John Michell, suggested that if something were sufficiently massive, “all light emitted from such a body would be made to return to it by its own power of gravity”.²

Furthermore, Einstein himself never actually derived a black hole from his own theory of relativity, and “never admitted the theoretical possibility of such an object,” stating that the “proposed physical basis for its existence was incorrect”.² It was the German astronomer Karl Schwarzschild who extracted the black hole from Einstein’s field equations. Experts claim it was Schwarzschild who “first obtained the solution and first predicted black holes, event horizons, and Schwarzschild radii, amongst other things”.² In 1960, American mathematician and physicist M. D. Kruskal, and Hungarian-Australian mathematician G. Szekeres, worked out a mathematical expression that would become the “cornerstone of modern relativists and is the theoretical justification of the black hole”.² The American theoretical physicist John Wheeler would coin the term “black hole” in the 1960’s. In 1996, the famous English theoretical physicist Stephen Hawking analyzed the quantum nature of back holes, stating that they have “intrinsic entropy” and that they “lose information from our region of the universe”.³

In April of 2017, The Event Horizon Telescope observed the M87 galaxy, 55 million light years away, over a span of four nights. The elliptical galaxy contains within it a supermassive black hole, which spins at the galaxy’s heart. “For the first time in human history, astronomers have combined the power of telescopes from across our planet to create an image that shows the event horizon of a black hole”.⁴ In April of 2019, the very first image ever captured of a black hole was unveiled to the entire world. This image made history as conclusive confirmation of the existence of black holes. While the ubiquitous virality of the image across social media and popular culture is a great example of science piquing public interest, black holes still remain mostly shrouded in mystery. “To be clear, you are not actually seeing the black hole itself,” notes American astronomer Phil Plait. “The gravity is bending the light from the material around it, sending it toward us, leaving a gap where the black hole itself is”.⁴ Plait goes on to describe the image more accurately as “the silhouette of the black hole’s gravity”.⁴ Scientists believe that there is a supermassive black hole at the center of nearly every big galaxy.

In summation, the lineage of the idea of the black hole can in some sense be traced all the way back to Isaac Newton, and while black holes largely remain shrouded in mystery, science is making great strides toward enriching our understanding of these incredible objects. The concept sounds like science fiction, but perhaps one day we will be able to harness a black hole’s incredible power for the benefit of humankind.