Until early in the last century, the best scientific minds of the day believed the universe was pervaded by an invisible substance called aether. According to prevailing theory, some medium was needed to propagate light, much as one needs air or some other substance to transit sound. However, aether had stubbornly defied every effort at detection. Eventually, Einstein dispensed with aether altogether in his theory of special relativity, not by disproving its existence but by demonstrating that the universe could function perfectly well without it.
Aether was not the first instance in which some invisible substance was believed to exist merely because it buttressed prevailing scientific theory -- nor is it likely to be the last. Scientists in the 17th and 18th centuries believed in a substance released by flammable materials during combustion called phlogiston that had no color, odor, taste or mass. It also eventually proved to have no existence. Scientists today theorize that 90 percent or more of the universe is made up of so-called “dark matter” that neither absorbs nor reflects light. Dark matter has so far defied all efforts at detection but is otherwise the only way to account for certain observable gravitational effects on galaxies. Observable gravitational effects on nearby planets led to the discovery of Neptune. It remains to be seen whether dark matter will prove to be another situation like Neptune or a 21st-century version of aether.
Einstein not only relegated aether to the dustbin of scientific theory, he also dismantled Newton’s tidy universe of absolute time and space. He theorized that time slowed down as objects speeded up, relative to certain frames of reference. He contended that space was curved and that light would bend to gravity. Einstein, who once described himself as a “believing physicist,” offered no evidence for any of this but did suggest ways his theories could be proved, challenging his colleagues to see for themselves. Einstein’s general theory of relativity was spectacularly confirmed in 1919 when Sir Arthur Eddington observed the gravitational deflection of starlight by the sun during a solar eclipse.
Now the point of all this is that belief in things not seen is hardly limited to the religious realm. For scientists, it can be the source of fresh discovery or acute embarrassment, depending on whether they can eventually turn up some facts to support their theories. Religious belief is not similarly constrained by the need to fit theory to facts, although ignoring facts can still lead to acute embarrassment, as witness the church’s heavy-handed attempts to silence Galileo for insisting the sun, rather than the earth, was center of the cosmos.
Religion is neither validated nor invalidated by its preoccupation with things not seen, since there is nothing inherent in that to distinguish a believer from a theoretical physicist. However, the conviction of things not seen, to borrow a phrase from St. Paul, can be problematical to the extent it becomes self-validating. Just as my beliefs are not true merely because I believe them to be so, neither does the sheer strength of my conviction make them a certainty. Einstein never insisted on the truth of his theories, although he did once quip that he would have felt sorry for the Lord if Eddington’s gravitational lensing experiment had failed to confirm general relativity, since the theory was correct. “Enough for me the mystery of the eternity of life,” Einstein later wrote, “and the inkling of the marvelous structure of reality. There is in this neither a will nor a goal, nor a must, but only sheer being.”
Albert Einstein, The World as I See It