A new theory of quantum gravity solves cosmology’s central mystery: what have physicists discovered?

For almost 100 years, scientists have known that the Universe is expanding. But in recent years it has become clear that different measurements of the expansion rate of the Universe, or the Hubble constant, lead to mysterious inconsistencies. To solve the problem, physicists propose incorporating quantum effects into the theory used to determine the rate of expansion of space. Therefore, scientists believe that a version of the theory of quantum gravity that combines quantum physics and Einstein’s theory of general relativity could help solve one of the main mysteries of cosmology. The results of the study were published in the journals Classical and Quantum Gravity, writes Live Science.

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Inconsistency in calculations when measuring the rate of expansion of space

The fact that the universe is expanding was first reported by astronomer Edwin Hubble in 1929. He found that the farther galaxies are from Earth, the faster they are moving away from us. Already in the 21st century, astrophysicists calculated the rate of expansion of space using observations of distant space objects and cosmic microwave background radiation (the light remaining after the Big Bang). However, it turned out that the difference in the Hubble constant value was approximately 10%. This discrepancy is called the Hubble problem and suggests that scientists may not fully understand the evolution of the Universe.

The authors of the new study proposed their own solution to this problem, which made it possible to reconcile the contradictions in the measurement results obtained. According to the authors, astrophysicists derive the Hubble constant indirectly using an evolutionary model of the Universe based on Einstein’s theory of general relativity.

Quantum effects

Scientists have proposed modifications to this theory to account for quantum effects. These effects, inherent in fundamental interactions, include random field fluctuations and the spontaneous creation of particles from the vacuum of space.

Although scientists have been able to incorporate quantum effects into other field theories, quantum gravity remains elusive. Therefore, it is very difficult, sometimes even impossible, to make such calculations. The study’s authors focused on the broad effects of quantum gravity, which are common to many proposed theories.

Hubble’s solution to the problem

The results showed that if we take into account quantum effects when describing gravitational interactions during cosmic inflation (the first stage of cosmic expansion), this changes the predictions of the theory of relativity regarding the properties of the cosmic microwave background radiation. Therefore, both obtained values ​​of the Hubble constant coincide in this case.

Scientists admit that this is only a theoretical work and final conclusions can be drawn only when a full-fledged theory of quantum gravity is created. But they think the results are encouraging.

According to physicists, the connection between the cosmic microwave background radiation and the effects of quantum gravity paves the way for experimental investigation of these effects in the near future.

If everything in space revolves around something, does the Milky Way do the same? As I wrote before, scientists have answered this question. Focus. Although the Earth and all the planets revolve around the Sun, things are much more complicated on the galactic scale.

Moreover Focus He wrote that, according to new research, black holes are not actually what they seem. Physicists thus offer a solution to the riddle of violations of known laws of physics in the depths of a black hole.