# Monica Guica

**PhD**

**Uppsala University**

**Natural sciences**

**Year of admission: 2015**

**Holograms in the sky**

Black holes are some of the most fascinating objects we observe in the sky. However, at a deep theoretical level, what they tell us is that the two theories we use to describe the world – General Relativity and Quantum Mechanics – are incompatible with each other.

The solution to this problem is believed to be holography, according to which all gravitational dynamics inside a given volume can be encoded on its bounding surface – just like a three-dimensional image is encoded on a two-dimensional holographic plate. Wallenberg Academy Fellow Monica Guica will investigate how holography works in the real world, by finding the holograms of black holes in the sky.

Holography is a general principle - deeply rooted in the properties of black holes - which tells us that the entire world around us can be encoded on a two-dimensional surface. Thus, gravity and one of the space-time dimensions are just “apparent”, or “emergent”; this is believed to resolve the above-mentioned tension between general relativity and quantum mechanics. While holography has been put on a very firm footing in the context of string theory - most notably through the AdS/CFT correspondence - our understanding of how it works in the real world is extremely poor.

Dr. Monica Guica at Uppsala University wants to investigate black holes in the sky – in particular, maximally spinning ones – as a crutch to understanding holography in our world. In the past, she has shown that maximally spinning black holes behave very similarly to their well-understood counterparts in AdS/CFT. Now, she would like to fully develop this connection and find how gravity in our world emerges from the black hole hologram.

*Photo: Markus Marcetic*