More than 25 years after the discovery of the accelerated expansion of the Universe, the physical nature of dark energy remains elusive. The Dark Energy Spectroscopic Instrument (DESI) is the first of a new generation of “Stage-IV” cosmology survey experiments aiming to improve this understanding. By precisely mapping the positions of over 50 million galaxies and quasars, DESI is measuring the...
The cosmological constant problem, the most serious fine-tuning problem for the standard model parameters, remains a major puzzle, especially in light of Weinberg’s no-go theorem, which forbids natural solutions if dark energy is constant.
Recent DESI observations suggest time variation in dark energy, opening a possible loophole. I present a model that realizes this idea to make the tuning...
Clustering dark energy is a class of models in which the speed of propagation of the perturbations in the dark energy component is small compared to the speed of light, causing the perturbations to collapse on scales inside the horizon and affecting the process of cosmic structure formation. This presentation will go over the effects we expect to detect in cosmological observations and how we...
Recently, there has been considerable debate regarding potential evidence for the dynamical nature of dark energy (DE), particularly in light of Baryon Acoustic Oscillations (BAO) measurements released by DESI survey. In this work, we propose an agnostic test that simultaneously constrains the dark energy (DE) equation of state (EoS) and probes the possibility of a transition between the...
