GoKawiilBen-Gurion University team builds interferometer to test gravity's effect on quantum waves
A physics team led by Ron Folman at Ben-Gurion University of the Negev, working with researchers from Germany, the UK and the US including Roger Penrose, has built an interferometer that splits a single atom into two simultaneous paths—one falling freely and one held still—that reconverge at the same point. This setup lets them measure how free fall changes the atom's quantum phase, something theorized nearly a century ago but never directly tested due to the need for ultracold atoms and a way to compare phase differences.
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The measurement addresses a long-standing gap between quantum mechanics and general relativity, two of physics' most successful but famously incompatible frameworks. If the century-old prediction about free fall's effect on quantum waves turns out to be wrong, it would signal a genuine conflict between gravity and quantum theory, potentially reshaping fundamental physics.
- Researchers built an interferometer giving a single atom two simultaneous paths, one in free fall and one held still.
- The experiment tests a nearly 100-year-old theoretical prediction about how gravity affects quantum wave phase.
- Success required ultracold atom technology only available since the late 1990s, plus a method to compare phase via path splitting.
Roger Penrose "The Road to Reality — Penrose, one of the collaborators on this atom interferometry experiment, wrote this sweeping guide to the mathematics and physics behind quantum mechanics and general relativity. It's the perfect follow-up if the article left you wanting to understand why free fall and quantum waves are so hard to reconcile. A dense but rewarding read you'll return to again and again.
See Roger Penrose "The Road to Reality on Amazon → Affiliate link — we may earn a commission on purchases, at no extra cost to you. Product picked by AI based on this article; it is not a tested recommendation.Source: arstechnica.com, 2026-09-11
Published there as: “What happens when quantum mechanics and relativity meet?”
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