The University of Southampton

Ant colony interactions offer new clues to understanding black hole and quark gluon plasma

Published: 11 June 2019
There are striking similarities between the collective behaviour of ants and the evaporating processes of black holes.

Physicists from the University of Southampton have identified striking similarities between the collective behaviour of ants and the evaporating processes of black holes.

The findings, which have been published in the Journal of High Energy Physics, relate string and gauge theory to ant theory by comparing the bound state of the different systems.

The linked dynamics have helped scientists understand the microscopic mechanism of the black hole evaporations.

Dr Masanori Hanada, of Southampton's School of Physics and Astronomy, collaborated with co-authors from the University of Tsukuba in Japan to relay the surprising finding.

"Stephen Hawking discovered that a black hole does not only absorb the things around it, but also radiates and gradually evaporates," Masanori explains. "This has led to widespread research into the quantum aspects of gravity, including the holographic principle and gauge theory which is intensively studied here in Southampton.

"A typical example of gauge theory is Quantum Chromodynamics (QCD) which transition to Quark-Gluon Plasma (QGP) at high temperatures. According to the holographic principle, black holes and QGP are essentially the same thing; however, we have been unable to explain the basic feature of why black holes become hotter as they evaporate, unlike usual quantum systems."

Curiously, Masanori discovered the answer when he immersed himself in British people's love of football.

"As a newcomer to the UK, I felt obliged to learn about football and bought a book called Soccermatics by British mathematician David Sumpter," he says. "Sumpter is an expert in the collective behaviour of animals, and in order to explain a certain aspect of football referred to the collective behaviour of ants. Strikingly, I could immediately see the same dynamics as string and gauge theory.

"In string theory, D-branes interact with each other via strings and form a bound state - a black hole. In the ant theory, ants interact with each other via pheromones and form a bound state - the ant trail. The natures of the interactions in these two seemingly different systems are essentially the same. In 2016, Jonathan Maltz (then at Berkeley) and I worked on this problem without knowing the ant theory, and figured out how D-branes should behave in order for the Hawking's calculation to be reproduced. The ant theory taught us why they behave that way.

"The ant theory has then taught us more. It has other kinds of phase diagrams with counterparts in gauge theory - including the actual QGP quark-gluon plasma created in colliders such as the Large Hadron Collider at CERN - and this has led us to a unified way of understanding the microscopic dynamics behind the phase transitions in various gauge theories."

Masanori joined the University of Southampton in 2018 as part of a five-year Ernest Rutherford Fellowship from the Science and Technology Facilities Council (STFC).

He is interfacing between the University's String Theory and Holography Group and Southampton High Energy Physics (SHEP) theory group, which are combined within the Southampton Theory Astrophysics and Gravity (STAG) Research Centre.

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