Researchers Subhasis Nalui and Subhra Bhattacharya from the Indian Association for the Cultivation of Science in Kolkata have delved into the theoretical realm of wormholes and their potential implications for our understanding of gravity and the universe. Their work, published in the journal Physical Review D, explores the design of wormholes within the framework of a novel power-law f(R) gravity model, offering insights that could have profound implications for the energy sector.
Wormholes, hypothetical tunnels through spacetime, have long captivated scientists and science fiction enthusiasts alike. In this study, Nalui and Bhattacharya consider the Morris-Thorne wormhole metric, a mathematical model that describes the geometry of a wormhole. They characterize the matter tensors within this metric using a linear equation of state, a relationship that describes how matter behaves under different conditions.
Using Einstein’s field equations within the context of f(R) gravity, a modified theory of gravity that extends general relativity, the researchers model solutions for both wormholes and f(R) gravity itself. They derive four distinct wormhole models, each supported by different power-law f(R) models. These models exhibit a range of properties, including solid angle deficits and varying degrees of asymptotic extendibility. Notably, one of the models is asymptotically flat with zero tidal force, a characteristic that could have practical implications for stable traversable wormholes.
The study also explores the parameter space of these models, revealing that they can support both null energy condition (NEC) satisfying and violating wormholes. NEC is a fundamental principle in general relativity that imposes constraints on the energy-momentum tensor. Interestingly, when the matter satisfies NEC, the associated f(R) model exhibits ghost behavior, a phenomenon that could have implications for the stability of these theoretical constructs.
To ensure the cosmological feasibility of their f(R) models, the researchers independently substantiate them, obtaining valid parameter spaces that align with cosmological observations. They also present suitable scalar-tensor representations of these models, leveraging the correspondence between f(R) gravity and Brans-Dicke (BD) theory, another modified theory of gravity.
Furthermore, the robustness of the wormhole solutions is analyzed using BD scalar fields in hybrid metric-Palatini gravity, yielding excellent results. The study also investigates the location of photon spheres around these wormholes and connects them with the Herrera Complexity factor in f(R) gravity. The findings indicate that the relationship between the complexity factor and the existence of photon spheres remains fundamentally unchanged in f(R) gravity compared to Einstein’s gravity.
While the practical applications of wormholes in the energy sector are still speculative, the theoretical insights gained from this research could contribute to our understanding of gravity, spacetime, and the fundamental forces that govern the universe. As our knowledge of these complex phenomena expands, so too does our potential to harness them for innovative energy solutions. The research was published in Physical Review D, a prestigious journal in the field of theoretical physics.
This article is based on research available at arXiv.