Research in Reverse

When scientists make sharp 180-degree turns in their thinking, it is often for one of two particular reasons

- Charles C. Mann

IF THERE IS A BEGINNING TIME POINT for the Age of Scientific Reversal, it may be 1887—the year when Albert A. Michelson and Edward W. Morley conducted what is often called the world's most famous failed physics experiment.

For more than two centuries researchers had proposed that light was a wave of some kind traveling through an ineffable material that pervaded everything, even the space between atoms. No evidence of this all-permeating substance—the aether, as it was called—had ever been detected. Still, most scientists firmly believed it must exist. How could a wave be seen to travel unless there were something it was traveling through? Working in Cleveland, Ohio, Michelson and Morley sought to measure the aether's effects with some of the most sensitive equipment ever built. To their shock, they found absolutely no trace of it.

Baffled and discouraged, the two men gave up plans for followup experiments. Other physicists were even more dismayed. The great theoretical physicist Hendrik Lorentz said the results put him “utterly at a loss.”

Yet they were not a loss for science. The Michelson-Morley tests actually led to a remarkable intellectual 180-degree turn and a forward leap in physics. The aether, scientists had believed, would provide a fixed background—a universal reference for all celestial objects. The discovery that outer space was a featureless, nearly empty vacuum—which stemmed from Michelson and Morley's work—meant that objects could be located only in reference to one another. And that realization fed into an even bigger 180-degree turn: Albert Einstein's theories of special and general relativity, which upended previous notions of gravity and turned space and time into a single curvature created by mass and energy.