At the Limits of Falsification

The NY Times has an essay by Adam Frank (Rochester) and Marcelo Gleiser (Dartmouth) on the tacit rejection of empiricism in, of all places, physics. From the essay,

Today, the favored theory for the next step beyond the standard model is called supersymmetry (which is also the basis for string theory). Supersymmetry predicts the existence of a “partner” particle for every particle that we currently know. It doubles the number of elementary particles of matter in nature. The theory is elegant mathematically, and the particles whose existence it predicts might also explain the universe’s unaccounted-for “dark matter.” As a result, many researchers were confident that supersymmetry would be experimentally validated soon after the Large Hadron Collider became operational.

That’s not how things worked out, however. To date, no supersymmetric particles have been found. If the Large Hadron Collider cannot detect these particles, many physicists will declare supersymmetry — and, by extension, string theory — just another beautiful idea in physics that didn’t pan out.

But many won’t. Some may choose instead to simply retune their models to predict supersymmetric particles at masses beyond the reach of the Large Hadron Collider’s power of detection — and that of any foreseeable substitute.

Implicit in such a maneuver is a philosophical question: How are we to determine whether a theory is true if it cannot be validated experimentally? Should we abandon it just because, at a given level of technological capacity, empirical support might be impossible? If not, how long should we wait for such experimental machinery before moving on: ten years? Fifty years? Centuries?

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