It is one of the all-time greatest physics experiments: such a classic that it’s taken a century to go one better. In the double-slit experiment of 1908, a photon fired at a pair of slits passed through both simultaneously and interfered with itself. This surprising effect provided one of the first clues to the weird world of quantum mechanics. Now precise measurements have been made on a version with three slits – and they again confirm the predictions of quantum mechanics.
Why are we still testing such predictions? It is not just tilting at windmills: physicists have long struggled to unite quantum mechanics with general relativity, which describes gravity, and some believe quantum mechanics will need tweaking to make this work. “The experiment is much harder than it might seem,” said James Franson, professor of physics, who was not involved in the study. “The slightest misalignment of the slits might produce errors.”
The article, “Triple-slit experiment confirms reality is quantum,” ran July 22 in the New Scientist.
Franson also wrote a “Perspectives” piece on the study that can be found here.
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