Physicists Find Limit to Backward Time
Tap title to read story
Relativity lets time run slower in strong gravity or at high speed, but it still flows one way. Quantum mechanics, however, opens a possibility for time to run backward. A new mathematical study by Yakir Aharonov of Tel Aviv University and Avshalom C. Elitzur of the Israel Institute for Advanced Research shows that the quantum environment itself limits how far back time can effectively run. In the simplest model explored, time could only run backward for about a femtosecond – one quadrillionth of a second. Their work is detailed in a preprint uploaded to arXiv. Aharonov’s earlier 1990 proposal of a quantum time‑translation machine also explored how superposition and post‑selection could make a system behave as if time had sped up, stopped, or even run backward.
More context
Timeline
- On January 1 1990 Aharonov proposes quantum time‑translation machine.
- On September 11 2026 ScienceDaily reports quantum limit on time reversal.
- On November 1 2026 Study confirms femtosecond limit on backward time.
Why it matters
Immediate US impact: Limited to academic research, no direct economic effect Possible long-term US impact: Potential influence on future quantum computing designs Most affected groups: Physicists, quantum engineers, academic institutions Reader priority: High for science enthusiasts and researchers
Coverage notes
Center: Coverage from lifeboat.com, Around Prague, sciencedaily.com frames this as a developing news story: Physicists Find Limit to Backward Time. Reporting emphasizes verified facts, named sources, and near-term impact for readers. Left: Left-leaning desks covering the same development typically emphasize public impact, institutional accountability, and who is most affected. Right: Right-leaning desks covering the same development typically emphasize practical outcomes, market or security stakes, and institutional response.
Primary report
ScienceAlert — Physicists Find Limit to Backward Time
Sources
JQJO Editorial Desk · Human reviewed · AI assisted. Report a correction.
