Similar to the situation cosmologists confront today, however, the physicists of 1904 had not yet been able to address a few challenges. The medium through which they believed light traveled the luminiferous ether should have induced variations in the speed of light, and yet light always moves through space at the same rate. Astronomers observed the orbit of Mercury to be slightly different from what Newtonian physics predicted, leading some to suggest that an unknown planet, dubbed Vulcan, might be perturbing Mercurys trajectory.

Physicists in 1904 had no idea what powered the Sun no known chemical or mechanical process could possibly generate so much energy over such a long time. Lastly, scientists knew various chemical elements emitted and absorbed light with specific patterns, none of which physicists had the slightest idea how to explain. In other words, the inner workings of the atom remained a total and utter mystery.

Although few saw it coming, in hindsight, its clear that these problems were heralds of a revolution in physics. And in 1905, the revolution arrived, ushered in by a young Albert Einstein and his new theory of relativity. We now know that the luminiferous ether does not exist and that there is no planet Vulcan. Instead, these fictions were symptoms of the underlying failure of Newtonian physics. Relativity beautifully solved and explained each of these mysteries without any need for new substances or planets.

Furthermore, when scientists combined relativity with the new theory of quantum physics, it became possible to explain the Suns longevity, as well as the inner workings of atoms. These new theories even opened doors to new and previously unimagined lines of inquiry, including that of cosmology itself.

Scientific revolutions can profoundly transform how we see and understand our world. But radical change is never easy to see coming. There is probably no way to tell whether the mysteries faced by cosmologists today are the signs of an imminent scientific revolution or merely the last few loose ends of an incredibly successful scientific endeavor.

There is no question that we have made incredible progress in understanding our universe, its history, and its origin. But it is also undeniable that we are profoundly puzzled, especially when it comes to the earliest moments of cosmic history. I have no doubt that these moments hold incredible secrets, and perhaps the keys to a new scientific revolution. But our universe holds its secrets closely. It is up to us to coax those secrets from its grip, transforming them from mystery into discovery.

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Is the Big Bang in crisis? | Astronomy.com - Astronomy Magazine