Key Takeaways
- A groundbreaking new theory aims to reconcile the long-standing conflict between Einstein’s theory of general relativity and quantum mechanics, proposing that spacetime itself may remain classical rather than being governed by quantum rules.
- Unlike existing frameworks like string theory and loop quantum gravity, this “postquantum theory of classical gravity” suggests modifying quantum mechanics instead of gravity, leading to random spacetime fluctuations.
- Experimental validation could involve testing whether the weight of a precisely measured object fluctuates, with implications for our understanding of the quantum versus classical nature of spacetime.
- The theory introduces a significant conceptual shift by challenging the necessity of the quantum measurement postulate, which could also address unresolved problems like black hole information loss.
- Pioneering experiments in the next two decades may reveal whether spacetime exhibits quantum properties, reshaping the foundations of physics.
Efforts to bridge the gap between quantum mechanics and Einstein’s theory of general relativity, two cornerstones of modern physics, have long been at an impasse. A novel theory introduced by Professor Jonathan Oppenheim of UCL proposes a radical approach: spacetime may remain classical, defying conventional assumptions of quantum behavior. This framework, called a “postquantum theory of classical gravity,” could redefine our understanding of the universe’s fundamental rules.
Classical Spacetime and Random Fluctuations
Traditional theories like string theory and loop quantum gravity suggest that spacetime must be “quantized” to align with quantum mechanics. However, Professor Oppenheim’s theory flips this notion, keeping spacetime classical while altering quantum mechanics itself. This results in unpredictable, large-scale fluctuations in spacetime, mediated by gravity. For instance, the precise weight of objects could vary slightly when measured with extreme accuracy.
These claims are not purely theoretical. A second paper published in Nature Communications outlines an experiment to measure mass fluctuations, such as a standard 1 kg weight, at the International Bureau of Weights and Measures in France. If the fluctuations are smaller than mathematically predicted, the theory would be invalidated. This innovative experiment has the potential to provide empirical evidence for the classical versus quantum nature of spacetime.
Testing and Implications
The UCL research group has spent five years exploring the theory’s implications and experimental feasibility. Co-authors Dr. Carlo Sparaciari and Dr. Barbara Šoda highlight the simplicity yet precision required for such tests, which would involve observing how long atoms or heavier particles can maintain superpositions. Another experimental path involves “gravitationally mediated entanglement,” where entangled particles interact via gravity.
Professor Sougato Bose of UCL, a pioneer in the entanglement experiment, believes these experiments could yield answers within the next 20 years. The stakes are high; prominent physicists like Carlo Rovelli and Geoff Penington have even placed a 5000:1 odds bet on whether spacetime’s nature is ultimately classical or quantum.
Beyond gravity, the theory has broader implications. It eliminates the need for quantum theory’s contentious measurement postulate by introducing a natural mechanism for superpositions to collapse. This also offers a new perspective on the black hole information paradox, suggesting that information may genuinely be lost due to spacetime’s inherent unpredictability.
Conclusion
By redefining the rules governing spacetime and quantum mechanics, this postquantum theory opens doors to transformative scientific discoveries. Its experimental proposals, while challenging, are within reach, promising to unravel mysteries that have perplexed physicists for over a century.
