Take Good Explanations Seriously
Progress begins where our best theories lead.
In 1916, the astrophysicist and mathematician Karl Schwarzschild applied the equations of Albert Einstein’s general relativity to derive the spacetime curvature inside stars. His work revealed that if a star were sufficiently massive and its radius sufficiently small, then spacetime would curve into itself, generating a point of infinite gravity where time stood still.
Schwarzschild shared these results with Einstein, but Einstein did not believe they were possible in physical reality.
Yet today we know that black holes exist, understand them as key elements in galaxy formation, and have captured them on camera.
It seems like Schwarzschild took Einstein’s theory, his explanation of gravity, more seriously than Einstein himself — at least as far as black holes went.
But black holes are not the only prediction of general relativity that Einstein didn’t trust.
At the time general relativity was published, most astronomers considered the Milky Way to be all there was in the Universe, with its stars moving relative to each other but maintaining a stable configuration. Yet the theory’s equations implied an expanding Universe. So, Einstein introduced the cosmological constant to counteract gravity and allow for a static Universe.
A decade later, Edwin Hubble’s observations showed that the Universe is indeed expanding, proving, once again, general relativity right and its creator wrong.
As Einstein’s biographer Walter Isaacson commented, if the physicist had trusted his predictions, “then Hubble’s confirmation of the expansion more than a decade later would have had as great an impact as when Eddington confirmed his prediction of how the sun’s gravity would bend rays of light. The Big Bang might have been named the Einstein Bang, and it would have gone down in history, as well as in the popular imagination, as one of the most fascinating theoretical discoveries of modern physics.”
Einstein didn’t follow his best theory, and one can’t help but wonder what further advances he could have made if he had.
Granted, few explanations are as deep and powerful as Einstein’s general relativity. But regardless of their reach and scope, we ought to take our best explanations seriously and follow their predictions wherever they might lead us.
Zoom in from the scale of black holes and the Big Bang to the domain of human health, and you’ll find many good explanations that are often ignored.
Our best explanation of smoking predicts irreversible damage to lungs, heart, and other organs. Our best explanation of exercise predicts that, all things equal, exercise increases our healthspan.
You might not like these predictions. But if you decide to ignore them, it’s at your own risk.
Only by trusting in our explanations can we make progress. Good explanations define operational constraints: the space of what is possible and what is not. They define the playing field for the next iteration of the infinite progress game.
As David Deutsch remarks in Chapter 1 of The Beginning of Infinity:
You may not like these predictions. Your friends and colleagues may ridicule them. You may try to modify the explanation so that it will not make them, without spoiling its agreement with observations and with other ideas for which you have no good alternatives. You will fail. That is what a good explanation will do for you: it makes it harder for you to fool yourself.
We might not like our best explanations, but we must follow them.
They will lead us to the edge of possibility, the adjacent possible space, where new and exciting problems await.