Sundance Osland Bilson-Thompson is an Australian theoretical

particle physicist Particle physics or high-energy physics is the study of fundamental particles and fundamental interaction, forces that constitute matter and radiation. The field also studies combinations of elementary particles up to the scale of protons and ...

. He has developed the idea that certain

preon In particle physics, preons are hypothetical point particles, conceived of as sub-components of quarks and leptons. The word was coined by Jogesh Pati and Abdus Salam, in 1974. Interest in preon models peaked in the 1980s but has slowed, as t ...

models may be represented topologically, rather than by treating preons as pointlike

particles In the physical sciences, a particle (or corpuscle in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass. They vary greatly in size or quantity, from s ...

. His ideas have attracted interest in the field of

loop quantum gravity Loop quantum gravity (LQG) is a theory of quantum gravity that incorporates matter of the Standard Model into the framework established for the intrinsic quantum gravity case. It is an attempt to develop a quantum theory of gravity based direc ...

, as they may represent a way of incorporating the

Standard Model The Standard Model of particle physics is the Scientific theory, theory describing three of the four known fundamental forces (electromagnetism, electromagnetic, weak interaction, weak and strong interactions – excluding gravity) in the unive ...

into loop quantum gravity at

Planck scale In particle physics and physical cosmology, Planck units are a system of units of measurement defined exclusively in terms of four universal physical constants: '' c'', '' G'', '' ħ'', and ''k''B (described further below). Expressing one of ...

Career

In 2004 and 2005 Bilson-Thompson was a Visiting Academic at the

University of Adelaide The University of Adelaide is a public university, public research university based in Adelaide, South Australia. Established in 1874, it is the third-oldest university in Australia. Its main campus in the Adelaide city centre includes many Sa ...

. From 2006 to 2009 he was a full-time academic at the Perimeter Institute for Theoretical Physics in

Waterloo, Ontario Waterloo is a city in the Canadian province of Ontario. It is one of three cities in the Regional Municipality of Waterloo (formerly Waterloo County, Ontario, Waterloo County). Waterloo is situated about west-southwest of Toronto, but it is n ...

, Canada. From 2010 he held a Ramsay Postdoctoral Fellowship at the University of Adelaide, Australia. In 2023 he was appointed a Research Fellow at the Centre for Quantum Computation and Communication Technology at

RMIT University The Royal Melbourne Institute of Technology (abbreviated as RMIT University) is a public research university located in the city of Melbourne in Victoria, Australia., section 4(b) Established in 1887 by Francis Ormond, it is the seventh-o ...

Research

There have been claims that loop quantum gravity may be able to reproduce features resembling the

. So far only the first generation of

leptons In particle physics, a lepton is an elementary particle of half-integer spin ( spin ) that does not undergo strong interactions. Two main classes of leptons exist: charged leptons (also known as the electron-like leptons or muons), includin ...

and

quarks A quark () is a type of elementary particle and a fundamental constituent of matter. Quarks combine to form composite particles called hadrons, the most stable of which are protons and neutrons, the components of atomic nuclei. All commonly o ...

with correct parity properties have been modelled by Sundance Bilson-Thompson using

s constituted of braids of spacetime as the building blocks. However, there is no derivation of the Lagrangian that would describe the interactions of such particles, nor is it possible to show that such particles are fermions, nor that the gauge groups or interactions of the Standard Model are realised. Utilization of

quantum computing A quantum computer is a computer that exploits quantum mechanical phenomena. On small scales, physical matter exhibits properties of wave-particle duality, both particles and waves, and quantum computing takes advantage of this behavior using s ...

concepts made it possible to demonstrate that the particles are able to survive

quantum fluctuation In quantum physics, a quantum fluctuation (also known as a vacuum state fluctuation or vacuum fluctuation) is the temporary random change in the amount of energy in a point in space, as prescribed by Werner Heisenberg's uncertainty principle. ...

s. In a 2005 paper, Sundance Bilson-Thompson proposed a model which adapted the Harari Rishon Model to preon-like objects which were extended ribbons, rather than point-like particles. This provided a possible explanation for why ordering of the subcomponents matters (giving rise to colour charge) whereas in the older Rishon Model, this feature must be treated as an ''ad hoc'' assumption. Bilson-Thompson refers to his extended ribbons as "helons", and his model as the Helon Model. This model leads to an interpretation of electric and colour charge as a topological quantities: electric charge as the number of twists carried on the individual ribbons, and colour charge as the number of variants of such twisting for a fixed electric charge. In a subsequent paper from 2006 Bilson-Thompson, Fotini Markopolou, and

Lee Smolin Lee Smolin (; born June 6, 1955) is an American theoretical physicist, a faculty member at the Perimeter Institute for Theoretical Physics, an adjunct professor of physics at the University of Waterloo, and a member of the graduate faculty of th ...

suggested that in any of a class of

quantum gravity Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics. It deals with environments in which neither gravitational nor quantum effects can be ignored, such as in the v ...

theories similar to

in which

spacetime In physics, spacetime, also called the space-time continuum, is a mathematical model that fuses the three dimensions of space and the one dimension of time into a single four-dimensional continuum. Spacetime diagrams are useful in visualiz ...

comes in discrete chunks, excitations of spacetime itself may play the role of preons, and give rise to the standard model of particle physics as an emergent property of the quantum gravity theory. Consequently, Bilson-Thompson ''et al.'' proposed that loop quantum gravity could reproduce the standard model. In this scenario the four forces would already be unified. The first generation of

fermions In particle physics, a fermion is a subatomic particle that follows Fermi–Dirac statistics. Fermions have a half-integer spin ( spin , spin , etc.) and obey the Pauli exclusion principle. These particles include all quarks and leptons and ...

with correct charge and parity properties have been modelled using preons constituted of braids of spacetime as the building blocks. Bilson-Thompson's original paper suggested that the higher-generation fermions could be represented by more complicated braidings, although explicit constructions of these structures were not given. The electric charge, colour, and parity properties of such fermions would arise in the same way as for the first generation. The model was expressly generalized for an infinite number of generations and for the weak force bosons, but not for photons or gluons, in a 2008 paper by Bilson-Thompson, Hackett, Kauffman and Smolin.

Implications for
Cosmology Cosmology () is a branch of physics and metaphysics dealing with the nature of the universe, the cosmos. The term ''cosmology'' was first used in English in 1656 in Thomas Blount's ''Glossographia'', with the meaning of "a speaking of the wo ...

The model has been implicated in a

cosmogony Cosmogony is any model concerning the origin of the cosmos or the universe. Overview Scientific theories In astronomy, cosmogony is the study of the origin of particular astrophysical objects or systems, and is most commonly used in ref ...

with a single-quantum origin as was proposed by

Georges Lemaître Georges Henri Joseph Édouard Lemaître ( ; ; 17 July 1894 – 20 June 1966) was a Belgian Catholic priest, theoretical physicist, and mathematician who made major contributions to cosmology and astrophysics. He was the first to argue that the ...

Politics

At the

2016 Australian federal election The 2016 Australian federal election was a double dissolution election held on Saturday, 2 July 2016, to elect all 226 members of the 45th Parliament of Australia, 45th Parliament of Australia, after an extended eight-week official campaign p ...

, Bilson-Thompson was the lead candidate for the Australian Cyclists Party on the

senate A senate is a deliberative assembly, often the upper house or chamber of a bicameral legislature. The name comes from the ancient Roman Senate (Latin: ''Senatus''), so-called as an assembly of the senior (Latin: ''senex'' meaning "the el ...

ballot paper for

South Australia South Australia (commonly abbreviated as SA) is a States and territories of Australia, state in the southern central part of Australia. With a total land area of , it is the fourth-largest of Australia's states and territories by area, which in ...

References

External links