A new model suggests that a companion anti-universe could explain the accelerated expansion without the need for dark energy

The accelerated expansion of the current universe, believed to be driven by mysterious dark energy, is one of the greatest puzzles in our understanding of the cosmos. The standard model of cosmology, called Lambda-CDM, explains this expansion as a cosmological constant in Einstein’s field equations. However, the cosmological constant itself lacks full theoretical understanding, especially with regard to its very small positive value.

To explain the accelerated expansion, physicists have proposed alternative explanations such as quintessence and modified theories of gravity, including scalar-tensor-vector gravity. Additionally, explanations outside of four dimensions, such as the dam world scenario in the Dvali-Gabadadze-Porrati (DGP) model, modify gravity over long distances due to the effect of multidimensional mass on our four-dimensional dam and variable dam tension.

My new model

In my paper, I propose another model to explain the current accelerated expansion of the universe. Unlike existing models, this does not require any form of dark energy or modified gravity approach. However, there is a price to pay: we need a partner anti-universe whose time flow is in the opposite relation to our universe.

There are strong arguments to support this concept. From the perspective of quantum theory, it is natural that the universe was created in pairs. Recently, Boyle et al proposed that the universe does not spontaneously break CPT (charge parity and time reversal symmetry), but that the universe after the Big Bang is the CPT image of the universe before it, pointing towards its anti-universe partner.

Recent results

In a recent paper published in Gravitation and cosmology, I used key concepts from quantum theory, such as relative entropy, and from general relativity, such as the zero-energy condition, which corresponds to the positive-energy condition. My findings suggest that the universe is naturally expanding at an accelerated rate.

Relative entropy, which requires two states, corresponds in this case to the universe and its anti-universe partner. Accelerated expansion appears to be inevitable in a universe created in pairs that obey the zero-energy condition. This result is quite surprising and readers familiar with Hawking’s surface theorem may notice some similarities. The surface theorem also deals with causal horizons and requires that the zero energy condition hold.

In our model, the causal horizon corresponds to the Big Bang. The results apply equally to the partner anti-universe.

In summary, the accelerating expansion of the universe is a challenging topic that continues to drive scientific efforts. Building on existing theories, my model offers an explanation using standard concepts from quantum theory and general relativity, without the need for elusive dark energy.

The results show that accelerated expansion is natural for a universe created in pairs. Moreover, the study of causal horizons can deepen our understanding of the universe. The beauty of this idea lies in its simplicity and naturalness, which distinguishes it from existing explanations.

This story is part of the Science X Dialog, where researchers can report findings from their published research articles. Visit this page for information about Science X Dialog and how to participate.