About:

Gravity and quantum mechanics are the two pillars of modern physics, but combining them into a consistent theory of quantum gravity remains an extremely challenging task. Perhaps the most successful approach to this problem is based on the holographic principle, which conjectures that theories of quantum gravity are equivalent to non-gravitational theories in a lower number of dimensions. To date, the most well understood example of this principle is the AdS/CFT correspondence.

Despite its many impressive successes, asymptotically AdS spacetimes are not a good approximation for the real world. Indeed our universe has a small, positive cosmological constant. This means that virtually all computations relevant for particle physics or gravitational waves are formulated for asymptotically flat spacetimes, while the natural settings for early- and late-universe cosmology are asymptotically de Sitter spacetimes.

In recent years, progress towards a holographic correspondence for spacetimes with zero or positive cosmological constant has been reignited. In asymptotically flat spacetimes, two distinct but related proposals have emerged: celestial and Carrollian holography. Moreover, there has been exciting progress in the computation of cosmological correlators, which provides new inspiration for holographic descriptions of spacetimes with a positive cosmological constant.

The sheer scope of progress across AdS/CFT, celestial holography, Carrollian holography, scattering amplitudes and cosmological correlators in recent years suggests that the study of holography in realistic backgrounds is on the verge of a breakthrough. The overarching goal of this workshop is therefore to bring together leading experts on these different areas in order to promote interdisciplinary discussions and collaboration in an informal atmosphere and to set an agenda for pursuing holography with non-negative cosmological constant by identifying the most promising new directions.