The presence of an anti-universe can explain the current accelerated expansion of the universe without the help of any form of dark energy, a new alternative cosmological model suggests. The accelerated expansion of the current universe, believed to be driven by mysterious dark energy, is one of the biggest 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 complete theoretical understanding, particularly with regard to its very small positive value. Naman Kumar, a PhD candidate at the Indian Institute of Technology, Gandhinagar, has proposed an alternative 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 approaches. However, the model assumes the presence of a companion antiuniverse whose time flow is oppositely related to our universe. His work has been published in the journal Gravitation and Cosmology. In his opinion, there are solid arguments supporting this concept. From a quantum theory perspective, it is natural that the universe is created in pairs. Recently, Princeton’s Latham Boyle and his team proposed that the universe does not spontaneously violate charge, parity, and time (CPT) reversal symmetry, but rather, the universe after the Big Bang is the CPT image of the previous universe, which points towards a companion anti-universe. In a recent paper published in Gravitation and Cosmology, Kumar 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. The findings suggest that the universe is naturally expanding rapidly. Relative entropy, which requires two states, in this case corresponds to the universe and its companion antiuniverse. Accelerated expansion seems inevitable in a universe created in pairs that respect the zero energy condition. This result is quite surprising and readers familiar with Hawking’s area theorem may notice some similarities. The area theorem also deals with causal horizons and requires that the zero energy condition be satisfied. In the new model, the causal horizon corresponds to the Big Bang. The results apply equally to the associated antiuniverse. “The results indicate that accelerated expansion is natural for a universe created in pairs. Furthermore, studying 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 “Concludes Kumar in an article published in Science X Dialog.
