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"Swamplandia": International Experts Gather in Search of a Quantum Gravity Theory

By comunicacion / September 18, 2023

**Last week, the Institute for Theoretical Physics (IFT UAM-CSIC) and Harvard University organized the largest scientific conference on the Swampland to date.****Swampland Program is crucial for advancing our understanding of the fundamental nature of the universe and the unification of the four fundamental forces of physics. To date, no definitive quantum gravity theory has been found, although various approaches, such as string theory, exist.****Renowed Professor Cumrun Vafa, Hollis Professor of Mathematics and Natural Philosophy in the Department of Physics at Harvard University, gave a public outreach lecture titled 'Puzzles to Unravel the Universe.'**

Last week, the Madrid *Real Jardín Botánico* hosted the international conference ‘Swamplandia’ on September 13, 14, and 15. The conference aims to explore uncharted territory in string theory, supergravity (in its low-energy approximation), and its relation to other disciplines such as scattering amplitudes, particle physics, quantum field theory, and holography. The Institute for Theoretical Physics (IFT UAM-CSIC) has been organizing Swampland conferences for several consecutive years, with 'Swamplandia' being the largest edition to date, featuring more than 120 participants from around the world, including renowned experts in the field. Additionally, this marks the first time the event is jointly organized with Harvard University.

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The concept "Swampland" is used in the context of theoretical physics to delineate the theoretical conditions and properties that must be met for a theory to be considered consistent and valid within the framework of quantum gravity and string theory. The choice of this metaphor is due to the idea that, much like one would avoid walking through a dangerous swamp due to the risks involved, theoretical physicists must avoid theories that do not meet certain theoretical and physical conditions to prevent problems or inconsistencies in their models.

Thus, the Swampland refers to a set of restrictions that theories must meet to be viable within the framework of quantum gravity and string theory. These restrictions include specific mathematical properties, such as bounds on the masses or charges of theory particles, and conjectures about how often rare processes can occur, which must be satisfied in any consistent theory of gravity.

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The problem of unifying the four fundamental forces of physics is one of the most important and exciting challenges in theoretical physics and cosmology. It involves the quest for a unified theory that explains and describes all the fundamental forces: gravity, strong nuclear force, weak nuclear force, and electromagnetism.

Gravity is governed by general relativity, while the other three forces are described by the Standard Model of particle physics, which is based on quantum mechanics and quantum field theory. These two descriptions, although successful in their respective domains, cannot be consistently combined into a single unified theory.

Miguel Montero, researcher at the IFT and one of the organizers of the Swamplandia event, explains: "Since gravity is such a weak force, we need very high energies to measure it directly. The idea of the Swampland is that there are very subtle and difficult-to-measure mathematical consistency conditions. Our task as theorists is to indicate where experiments should start."

Quantum gravity is, therefore, the theory that unifies quantum mechanics with the theory of general relativity, explaining how the gravitational force behaves at very high energies, where quantum mechanics dominates. The key idea of the Swampland is that quantum effects of gravity also manifest themselves at low energies.

The study of the Swampland can help researchers identify promising theories that are consistent with quantum gravity and discard those that are not. This is crucial for advancing our understanding of the fundamental nature of the universe and the unification of the four fundamental forces of physics.

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On Friday 15th, once the scientific lectures had concluded, distinguished Professor Cumrun Vafa, the Hollis Professor of Mathematics and Natural Philosophy in the Department of Physics at Harvard University, delivered a public outreach lecture titled 'Puzzles to Unravel the Universe.' Vafa is one of the organizers of the Swamplandia conference and is also one of the historical founders of this theoretical framework.

Vafa is one of the founders of duality in string theory, a revolution that has reshaped our understanding of the fundamental laws of the universe. He has uncovered mysteries of black holes using topological aspects of string theory and is the founder of 'F-theory,' which is one of the most promising directions for connecting solutions in string theory, known as the 'string landscape,' with particle physics.

His ideas related to seemingly consistent but ultimately inconsistent theories of quantum gravity, which he initiated in the 'Swampland' project, have helped narrow down the vast string landscape. Currently, this is an active area of research with significant impact in both cosmology and particle phenomenology.

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