Title: Dimensional Reduction in Quantum Gravity & Fractal Spacetime from the Quantum Browian Motion Perspective.
Speaker: Bei-Lok Hu (University of Maryland).
Abstract: Many approaches to quantum gravity find that spacetime near the Planck scale (10^33cm) becomes effectively two-dimensional. Recently there are proposals that the structure of spacetime becomes fractal at such a scale. Rather than relying on a postulated theory for the microscopic structure of spacetime as with strings, loops or sets, here we examinine this issue starting from low energy known theories, such as semiclassical gravity, where the vacuum expectation values of the stress energy tensor of a quantum matter field act as a source in driving the classical spacetime dynamics. Quantum Brownian motion has been a useful paradigm for the inclusion of matter field fluctuations in the establishment of stochastic gravity based on the Einstein-Langevin equation. When only the two point functions of the stress tensor are included, solutions for the metric fluctuations (“spacetime foam”) have been found for Minkowski and de Sitter spacetimes Higher moments of the stress-energy tensor have been shown to be just as important which leads to novel phenomena even at today’s low energy. Here we ask the question, would including non-Gaussian noise sources, or higher moments of the stress energy tensor in a self-consistent backreaction study of the spacetime dynamics reveal the underlying fractal structure of spacetime? This is motivated by the anomalous diffusion processes where multi-scale wave operators need be introduced to account for the effects deviating from the usual Brownian motion. This approach offers a useful key to unlocking the mesoscopic behavior of spacetime, which is a more meaningful and accessible regime, being the common denominator of all theories of quantum gravity and a connector to more verifiable low energy phenomena.
Time: Friday 7th October 2016, 2pm.
Place: Lecture Room, 1st Floor, School of Theoretical Physics, DIAS, 10 Burlington Road, Dublin 4.
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Last Updated: 9th November 2016 by George Rogers
Friday 21st October: STP Seminar – “Dimensional Reduction in Quantum Gravity & Fractal Spacetime from the Quantum Browian Motion Perspective”
Title: Dimensional Reduction in Quantum Gravity & Fractal Spacetime from the Quantum Browian Motion Perspective.
Speaker: Bei-Lok Hu (University of Maryland).
Abstract: Many approaches to quantum gravity find that spacetime near the Planck scale (10^33cm) becomes effectively two-dimensional. Recently there are proposals that the structure of spacetime becomes fractal at such a scale. Rather than relying on a postulated theory for the microscopic structure of spacetime as with strings, loops or sets, here we examinine this issue starting from low energy known theories, such as semiclassical gravity, where the vacuum expectation values of the stress energy tensor of a quantum matter field act as a source in driving the classical spacetime dynamics. Quantum Brownian motion has been a useful paradigm for the inclusion of matter field fluctuations in the establishment of stochastic gravity based on the Einstein-Langevin equation. When only the two point functions of the stress tensor are included, solutions for the metric fluctuations (“spacetime foam”) have been found for Minkowski and de Sitter spacetimes Higher moments of the stress-energy tensor have been shown to be just as important which leads to novel phenomena even at today’s low energy. Here we ask the question, would including non-Gaussian noise sources, or higher moments of the stress energy tensor in a self-consistent backreaction study of the spacetime dynamics reveal the underlying fractal structure of spacetime? This is motivated by the anomalous diffusion processes where multi-scale wave operators need be introduced to account for the effects deviating from the usual Brownian motion. This approach offers a useful key to unlocking the mesoscopic behavior of spacetime, which is a more meaningful and accessible regime, being the common denominator of all theories of quantum gravity and a connector to more verifiable low energy phenomena.
Time: Friday 7th October 2016, 2pm.
Place: Lecture Room, 1st Floor, School of Theoretical Physics, DIAS, 10 Burlington Road, Dublin 4.
Category: School of Theoretical Physics News & Events, Uncategorised
Happy Birthday! twitter.com/thecelticist/s…
The papers were 1) Affine Field Theory: conservation identitites and relation to Weyl and Eddington 2)The Union of the three fundamental fields (Gravitation, Menson, Electromagnetism) Which went on to secure worldwide acclaim. #DIASdiscovers
Date: 01 December 1943 Paper: The Irish Press Headline: Two Papers by Dr. Schroedinger Synopsis: 1943 was a busy year for Schroedinger. Not only did he deliver the "What is Life?" Lectures in @tcddublin in February in November he delivered two papers in the @RIAdawson (1/2)
Available to buy on the DIAS bookshop: books.dias.ie/index.php?main… (5/5) #DIASdiscovers #celtic #studies #twopatricks
"In the lives of St. Patrick, the two saints are invariably fused into one", said Prof. O'Rahilly in his lecture. The lecture was a condensation from O’Rahilly’s book “The two Patricks: a lecture on the history of Christianity in fifth-century Ireland”. (4/5)
He was known by his first name Patricius, which in later times would lead to confusion as he was succeeded by another apostle of the same name (Saint Patrick or Patricius in Latin). (3/5)
He spoke on "Palladius and Patrick". Palladius was the first bishop of the Christians of Ireland. (2/5)
Date: 21st March 1942 Paper: The Irish Press Headline: Palladius and Patrick | School Of Celtic Studies Lecture Synopsis: The first public lecture under the auspices of the School of Celtic Studies was delivered in Trinity College by Professor T. F. O'Rahilly in 1942. (1/5)
As part of our ongoing participation in the @HistFest we decided to take a look into the Irish Newspaper Archives and see where DIAS made it into print over the last 80 years. There were so many articles, the hardest part was selecting what we would post. We hope you enjoy!
@AReillyFailte @CultureNight @VisitDublin Thanks Antoinette! Glad you enjoyed 😊
Big thank you to @MartinaPQuinn of @helloalicepr for moderating the discussion, and of course to our panel @NeasaMcG @CormacORafferty and @laoneill111
@CormacORafferty "to cut yourself off from fundamental research means you could miss out on some of the biggest ideas"
@laoneill "it's our job as researchers to keep reminding governments how important basic research is" "For Dev basic research being carried out in Ireland was a badge of pride"
@NeasaMcG Schrödinger's work in causality was not well received by the religious authorities at the time At the same time DIAS did have Catholic priests working on research projects in the early days, so there was not the conflict you might think between science and religion
@laoneill111 Schrödinger was very popular in social circles in Dublin, a bit of a renaissance man
@CormacORafferty Schrödinger was gifted at explaining difficult concepts
@CormacORafferty on how unsuccessful work, in Schrödinger's case, unified field theory, is just as important part of science. And no one has managed to crack it yet! And not forgetting the cat
@laoneill111 how Schrödinger's book inspired scientists to change fields and result in the finding of the double helix.