Researchers at the University of Waterloo say a new "quadratic quantum gravity" framework could explain the universe's rapid early expansion without adding extra ingredients to Einstein's theory by hand. The idea is especially notable because it makes testable predictions, including a minimum level of primordial gravitational waves that future experiments may be able to detect. "Even though this model deals with incredibly high energies, it leads to clear predictions that today's experiments can actually look for," said Dr. Niayesh Afshordi, professor of physics and astronomy at the University of Waterloo and Perimeter Institute (PI). "That direct link between quantum gravity and real data is rare and exciting." Phys.org reports: The research team found that the Big Bang's rapid early expansion can emerge naturally from this simple, consistent theory of quantum gravity, without adding any extra ingredients. This early burst of expansion, often called inflation, is a central idea in modern cosmology because it explains why the universe looks the way it does today. Their model also predicts a minimum amount of primordial gravitational waves, which are tiny ripples in spacetime geometry created in the first moments after the Big Bang. These signals may be detectable in upcoming experiments, offering a rare chance to test ideas about the universe's quantum origins. [...] The team plans to refine their predictions for upcoming experiments to explore how their framework connects to particle physics and other puzzles about the early universe. Their long-term goal is to strengthen the bridge between quantum gravity and observational cosmology. The research has been published in the journal Physical Review Letters.

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