For centuries, scientists have been trying to unify two fundamental theories – Einstein’s general theory of relativity, which describes gravity and cosmic scales, and quantum mechanics, which governs the world of particles. But their incompatibility remains one of the unsolved problems of modern physics. The breakthrough may come from a new concept of quantum gravity, which arises from entropy – chaos in a system. This idea not only brings us closer to a “Theory of Everything” but also offers a solution to the mysteries of dark matter and dark energy, which make up 95% of the Universe. The study is published in the journal Physical Review D.
Why is gravity not “friendly” with the quantum world?
Since 1915, the general theory of relativity has remained the most accurate description of gravity: massive objects bend space-time, creating a force of attraction. However, this theory loses its validity in the micro-world where quantum mechanics dominates. Attempts to unify them run into the lack of a theory of quantum gravity that explains how gravity works at the particle level.
The “dark universe” additionally complicates the situation. Dark matter (27% of the cosmos) and dark energy (68%), are not only invisible and unexplored, but also do not obey the physical laws described by Einstein. The ordinary matter we see is only 5% of the Universe.
Entropy as a key to quantum gravity
Research by Ginestra Bianconi, a professor at the University of London, suggests a radical approach. It suggests that quantum gravity may arise from quantum relative entropy, a measure of the differences between quantum states. The idea is that the spacetime metric can be represented as a quantum operator that changes the state of the system.
This gives rise to new equations similar to Einstein’s equations in weak gravity, but with critical differences. For example, the theory suggests the existence of a cosmological constant, which better explains the accelerated expansion of the Universe due to dark energy. In addition, a G-field, a hypothetical structure capable of mimicking the gravitational effects of dark matter, follows from the model.
Why is this important?
- Dark energy explanation: the cosmological constant predicted by the theory fits the experimental data better than other models.
- G-field vs. dark matter: if the G-field exists, it could replace the need for dark matter, changing the way we look at the structure of galaxies.
- Combining theories: Bianconi’s approach opens the way to integrating relativity and quantum mechanics through entropy, a concept not previously considered in the context of gravity.
There are theory tests ahead. Experimental confirmation of the G-field or the cosmological constant could be a revolution. However, the study remains theoretical for the time being.
“If our model is correct, it will change the understanding of gravity and the dark Universe,” notes Bianconi.
Although the “Theory of Everything” is still a long way off, this work provides new instruments for unraveling the deep mysteries of the cosmos. Perhaps entropy will be the bridge that unites the worlds of Einstein and quantum physics.
Earlier we reported on the Top 5 misconceptions of science about the cosmos.
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