Bouncing Cosmology and the Early Universe: From Theory to Observations

Dear Colleagues,

Bouncing cosmology offers an alternative to the Big Bang by positing cyclic phases of contraction and expansion, avoiding singularities. Theoretical advances, such as loop quantum cosmology and \(f(R)\) gravity, provide mechanisms for a smooth bounce via quantum corrections and higher-order modifications. Ekpyrotic models using scalar fields address issues such as anisotropy, enhancing the plausibility of these scenarios.

Observations from the CMB and large-scale structure constrain bouncing cosmologies. Features such as suppressed power at large scales and specific non-Gaussian patterns could distinguish these models from inflationary paradigms. Data from Planck and BICEP/Keck collaborations already support aspects of certain bounce models. Upcoming missions, such as LiteBIRD, aim to refine these constraints further, testing the models' predictions against inflation.

Bouncing cosmology also connects with broader early-universe phenomena. Mechanisms for pre-bounce baryogenesis offer solutions to the matter–antimatter asymmetry. Links between bouncing models and late-time observations, such as cosmic acceleration and primordial string remnants, suggest a potential to address dark energy and dark matter within this framework. These developments demonstrate the potential of bouncing cosmology as a compelling alternative framework for understanding the universe’s origins.

Dr. Arnab Dasgupta
Guest Editor

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