Sabrina Pasterski's celestial holography seeks quantum gravity clues

Sabrina Pasterski, a physicist at Canada's Perimeter Institute for Theoretical Physics, is advancing a celestial holography framework to reconcile quantum theory with general relativity. Her work proposes treating the universe as a projection from a two-dimensional celestial sphere, with potential testable predictions emerging from gravitational wave observations.

Pasterski began developing the mathematical groundwork for this approach during her PhD with Andrew Strominger at Harvard University around 2018. Her hypothesis starts with particle collisions, imagining the resulting debris as points of data on a celestial sphere infinitely far away. Information like energy is encoded on this sphere, which is analogous to the night sky. She refers to the mathematical constraints and equations governing this translation as a 'grammar' for celestial holography. The research focuses on gravity, black holes, and the fundamental relationship between quantum physics and space-time, exploring whether our four-dimensional universe can be completely described by a theory with fewer dimensions.

Testable predictions and observational pathways

A significant outcome of Pasterski's celestial holography is the generation of specific, observable effects. She suggests potential testable predictions include the spin memory effect in gravitational waves. This subtle effect could be detected by future space-based observatories like the Laser Interferometer Space Antenna (LISA) within the next ten years. In recent collaborative work with Justin Kulp at Stony Brook University, Pasterski showed how to translate between the boundary of the celestial sphere and real space for systems involving multiple particles, a crucial step toward concrete predictions.

She also proposes using existing particle colliders like the Large Hadron Collider to hunt for hints of holography. In this approach, detectors such as CMS would be treated as holographic spheres, with physicists looking for distinctive geometric patterns in the distribution of energy during collisions.

Institutional support and methodology

Pasterski leads the Celestial Holography Initiative at the Perimeter Institute. This major research program is supported by an $8 million grant from the Simons Foundation, enabling collaborative work with institutions like Stony Brook University to advance the framework.

Scientific context and limitations

The work builds upon the foundational AdS/CFT correspondence proposed by Juan Maldacena in 1997. That duality describes a relationship between a three-dimensional curved space-time and a two-dimensional quantum surface, suggesting a holographic principle for the universe. Celestial holography seeks a similar equivalence between quantum theory and general relativity but addresses the significant challenge of applying holographic principles to our flat, not curved, spacetime.

A key difference lies in entanglement. While entanglement is well-understood in Maldacena's AdS/CFT framework, Pasterski notes it is harder to generalize to flat space. Her work shows that flat-space regions associate with reduced entanglement on the boundary compared to the AdS/CFT case. She is clear that this research does not claim to have found the final answer to quantum gravity. Instead, it explores powerful mathematical ideas to understand gravity at the quantum level.

Pasterski's personal history, including building and flying her own single-engine airplane as a teenager and graduating from MIT with a perfect GPA, has led some media outlets to describe her as the next Einstein. Her focus, however, remains on the physics. She uses the Christian concept of the Holy Trinity as a metaphor for duality in her work, though she states she is not religious. On the ultimate nature of reality suggested by her research, Sabrina Pasterski said: "It's bullshit." She does not believe she lives in a hologram but finds the mathematical framework powerful for asking fundamental questions about reality.