Sundance Osland Bilson-Thompson is an Australian theoretical
particle physicist
Particle physics or high energy physics is the study of Elementary particle, fundamental particles and fundamental interaction, forces that constitute matter and radiation. The fundamental particles in the universe are classified in the Standa ...
. He has developed the idea that certain
preon
In particle physics, preons are 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 the Standard Mode ...
models may be represented
topologically
In mathematics, topology (from the Greek words , and ) is concerned with the properties of a geometric object that are preserved under continuous deformations, such as stretching, twisting, crumpling, and bending; that is, without closing ho ...
, rather than by treating preons as pointlike
particles
In the physical sciences, a particle (or corpuscule 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 su ...
. His ideas have attracted interest in the field of
loop quantum gravity
Loop quantum gravity (LQG) is a theory of quantum gravity, which aims to merge quantum mechanics and general relativity, incorporating matter of the Standard Model into the framework established for the pure quantum gravity case. It is an attem ...
,
as they may represent a way of incorporating the
Standard Model
The Standard Model of particle physics is the theory describing three of the four known fundamental forces (electromagnetism, electromagnetic, weak interaction, weak and strong interactions - excluding gravity) in the universe and classifying a ...
into loop quantum gravity.
This would make loop quantum gravity a candidate
theory of everything
A theory of everything (TOE or TOE/ToE), final theory, ultimate theory, unified field theory or master theory is a hypothetical, singular, all-encompassing, coherent theoretical framework of physics that fully explains and links together all asp ...
.
Career
In 2004 and 2005 Bilson-Thompson was a Visiting Academic at the
University of Adelaide
The University of Adelaide (informally Adelaide University) is a public research university located in Adelaide, South Australia. Established in 1874, it is the third-oldest university in Australia. The university's main campus is located on N ...
. From 2006 to 2009 he was a full-time academic at the
Perimeter Institute for Theoretical Physics
Perimeter Institute for Theoretical Physics (PI, Perimeter, PITP) is an independent research centre in foundational theoretical physics located in Waterloo, Ontario, Canada. It was founded in 1999. The institute's founding and major benefactor i ...
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. Due to the c ...
, Canada. From 2010 he held a Ramsay Postdoctoral Fellowship at the University of Adelaide, Australia.
Summary of Bilson-Thompson's research
There have been recent claims that loop quantum gravity may be able to reproduce features resembling the
Standard Model
The Standard Model of particle physics is the theory describing three of the four known fundamental forces (electromagnetism, electromagnetic, weak interaction, weak and strong interactions - excluding gravity) in the universe and classifying a ...
. 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), and neutr ...
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
preon
In particle physics, preons are 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 the Standard Mode ...
s constituted of braids of spacetime as the building blocks. However, there is no derivation of the
Lagrangian
Lagrangian may refer to:
Mathematics
* Lagrangian function, used to solve constrained minimization problems in optimization theory; see Lagrange multiplier
** Lagrangian relaxation, the method of approximating a difficult constrained problem with ...
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
Quantum computing is a type of computation whose operations can harness the phenomena of quantum mechanics, such as superposition, interference, and entanglement. Devices that perform quantum computations are known as quantum computers. Though ...
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 the ...
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 vi ...
theories similar to
loop quantum gravity
Loop quantum gravity (LQG) is a theory of quantum gravity, which aims to merge quantum mechanics and general relativity, incorporating matter of the Standard Model into the framework established for the pure quantum gravity case. It is an attem ...
in which
spacetime
In physics, spacetime is a mathematical model that combines the three dimensions of space and one dimension of time into a single four-dimensional manifold. Spacetime diagrams can be used to visualize relativistic effects, such as why differen ...
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
In physics, the fundamental interactions, also known as fundamental forces, are the interactions that do not appear to be reducible to more basic interactions. There are four fundamental interactions known to exist: the gravitational and electrom ...
would already be unified. The first generation of
fermions
In particle physics, a fermion is a particle that follows Fermi–Dirac statistics. Generally, it has a half-odd-integer spin: spin , spin , etc. In addition, these particles obey the Pauli exclusion principle. Fermions include all quarks 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.
Politics
At the
2016 Australian federal election
The 2016 Australian federal election was a double dissolution election held on Saturday 2 July to elect all 226 members of the 45th Parliament of Australia, 45th Parliament of Australia, after an extended eight-week official campaign period. It ...
, Bilson-Thompson was the lead candidate for the
Australian Cyclists Party
The Australian Cyclists Party was a minor political party in Australia. It was registered with the New South Wales Electoral Commission in 2014, and unsuccessfully contested the 2015 New South Wales state election. It was also registered later wit ...
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 state in the southern central part of Australia. It covers some of the most arid parts of the country. With a total land area of , it is the fourth-largest of Australia's states and territories ...
.
References
External links
Sundance Bilson-Thompson's blog
{{DEFAULTSORT:Bilson-Thompson
Living people
Year of birth missing (living people)
21st-century Australian physicists