New Theory Explains How Time Began

Why It Matters

A viable, testable link between quantum gravity and the universe’s origin could transform fundamental physics and guide next‑generation gravitational‑wave experiments.

Key Takeaways

• Quadratic gravity transition offers a potential solution to quantum gravity.
• Universe originated as four‑dimensional space before a time dimension emerged.
• Quantum fluctuations triggered rapid expansion akin to inflation, then reheated matter.
• Model predicts distinctive primordial gravitational‑wave spectrum detectable by future observatories.
• Transition details are phenomenological, leaving a theoretical gap to resolve.

Summary

A recent Physical Review Letters paper from Perimeter Institute proposes that the universe began as a four‑dimensional space, with one dimension converting into time through quantum fluctuations. The authors argue that a transition from Einstein’s low‑energy gravity to a high‑energy ‘quadratic gravity’ regime resolves the long‑standing incompatibility between general relativity and quantum mechanics.

Quadratic gravity features a dimension‑less coupling, allowing a consistent quantum description where the usual Newton constant’s units cause divergences. In the model, the pre‑big‑bang state lacks a temporal direction; quantum fluctuations create a ‘border’ where a spatial dimension becomes temporal, initiating a rapid, inflation‑like expansion that later reheats into ordinary matter, radiation, and dark matter.

The team highlights that the early‑universe expansion would generate a characteristic spectrum of primordial gravitational waves, offering a concrete observational test. However, they acknowledge that the specific form of the Einstein‑to‑quadratic transition is introduced phenomenologically rather than derived from first principles, leaving a gap that future work must address.

If validated, the framework could unify gravity with quantum theory while simultaneously explaining the big bang, inflation, and matter creation, reshaping cosmology and particle physics. Its testable predictions make it a rare bridge between speculative theory and empirical verification, though its provisional assumptions temper immediate acceptance.

Original Description

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The biggest open problem in the foundations of physics is that Einstein’s theory of gravity, General Relativity, does not cooperate with quantum mechanics. Physicists have tried to solve this issue by coming up with a theory of quantum gravity, but those theories fall apart when you need them most – inside of black holes and at the Big Bang. Recently, though, physicists published a new calculation for the Big Bang, with a theory called quadratic gravity, which lets us skip over quantum gravity entirely, and that could explain the origin of time. Let’s take a look.

Paper: https://journals.aps.org/prl/abstract/10.1103/6gtx-j455

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#science #sciencenews #physics #gravity

This video discusses a new explanation for the beginning of the universe, published in PRL, which addresses quantum gravity and the period before time began. It features a presenter discussing "Asymptotically Safe Gravity" and includes scientific graphics and charts related to cosmological research. This new idea elegantly addresses the origin of the universe and offers a fresh perspective on space time, making it a significant contribution to science news.