Colloquia will be offered Fridays at 2:00 p.m. in SE 319. For more information contact Professor Ata Sarajedini asarajedini@fau.edu.
Date  Speaker  Title 

Jan. 28  Dongxue Que (FAU) 
Computational Aspects of Quantum Gravity: Numerical methods in spinfoam models. View abstract.

Colloquia will be offered Fridays at 2:00 p.m.in SE 319. For more information contact Professor Jon Engle at jengle7@fau.edu.
Date  Speaker  Title 

Sept. 24  Dongxue Que (FAU)  Complex critical points and curved geometries in 4D Lorentzian spinfoam quantum gravity. View abstract. 
Sept. 17  Dr. Liwei Ji (FAU)  Toward Moving Puncture Simulations with the GHG System. View abstract . 
Oct. 8  Shahabeddin Mostafanazhad Aslmarand (FAU)  Quantum Entanglement from a Geometric Perspective. View abstract . 
Oct. 30  Touhid Feghhi (FAU)  TBA 
Nov. 5  Prof. Muhammad Maqbool (U. of Alabama at Birmingham)  Construction of titanium doped AIN infrared microlaser in whispering gallery mode and its possible biomedical applications. View abstract. 
Nov. 19  Prof. J. S. Faulkner (FAU)  Teaching graduate quantum mechanics in the twentyfirst century. View abstract . 
Date  Speaker  Title  Virtual Information 

Dec 4  Dr. Juan Margalef  Covariant phase space: geometry and applications  Coming Soon 
Date  Speaker  Title 

Jan 26  J.B. Sokoloff  A Proposed Mechanism for the Difference in the Radius Dependence of Water Flow through Carbon and Boron Nitride Nanotubes 
Feb 2  Prof. Zonghong Zhu  Gravitational Lensing of Gravitational Waves and precision cosmology 
Feb 23  Dr. Ted von Hippel  White Dwarfs, Gaia, and The Age of the Galaxy 
Mar 30  Prof. Ariel Edery  Spontaneous Breaking of Restricted Weyl Symmetry in Pure R^2 Gravity 
A Propos ed Mechanism for the Difference in the Radius Dependence of Water Flow through Carbon and Boron Nitride Nanotubes
J.B. Sokoloff (Northeastern University)
Falk, et. al., proposed a mechanism that qualitatively explains the large dependence on the tube radius of the slip length and permeability of water flowing through carbon nanotubes. Despite the fact that boron nitride nanotubes have a crystal structure that is similar that of carbon nanotubes, such large radius dependence of the slip length and permeability on tube radius is not observed in boron nitride nanotubes. The enhancement of the slip length and permeability when the radius reaches 15nm, which is much larger than the size of a water molecular and atomic spacing in the tube wall in carbon, but not boron nitride nanotubes, observed by Secchi, et. al., can be accounted for by a reduction in the contribution to the friction from electron excitations in the wall as the radius decreases, resulting from the dependence of the electron energy band gap on the tube radius.
White Dwarfs, Gaia, and The Age of the Galaxy
Dr. Ted von Hippel (Embry Riddle Aeronautical University)
What is the starformation history of the Milky Way? How old are Galactic halo and thick disk stars? Traditional agedating of stars relies on clusters, which only offer a limited view of these stellar populations. I will show that white dwarf stars offer a way forward. Specifically, I will show how optical and nearIR photometry, Gaia astrometry, and a Bayesian modeling approach allows us to determine precision ages (within 2%5%) for individual white dwarfs and derive population ages.
Gravitational lensing of gravitational waves and precision cosmology
Prof. Zonghong Zhu
The standard siren approach of gravitational wave cosmology appeals to the direct luminosity distance estimation through the waveform signals from inspiralling double compact binaries, especially those with electromagnetic counterparts providing redshifts. It is limited by the calibration uncertainties in strain amplitude and relies on the fine details of the waveform. We will show the next generation detector, e.g., the Einstein Telescope is expected to produce 10^4 −10^5 gravitational wave detections per year, 50−100 of which will be lensed. Then we report a waveformindependent strategy to achieve precise cosmography by combining the accurately measured time delays from strongly lensed gravitational wave signals with the images and redshifts observed in the electromagnetic domain. We demonstrate that just 10 such lensing systems can provide a Hubble constant uncertainty of 0.68% for a flat Lambda Cold Dark Matter universe in the era of thirdgeneration groundbased detectors
Spontaneous Breaking of Restricted Weyl Symmetry in Pure R^2 Gravity
Prof. Ariel Edery
Recent work has shown that pure R^2 gravity (i.e. R^2 gravity with no extra R term) has a symmetry that is larger than scale symmetry and smaller than full Weyl symmetry. This has been dubbed restricted Weyl symmetry as it involves a Weyl transformation where the conformal factor has a constraint. Most importantly, this symmetry is spontaneously broken when the vacuum (background spacetime) has a nonzero Ricci scalar. In this case, the theory can be shown to be equivalent to Einstein gravity with nonzero cosmological constant and a massless scalar field. The massless scalar field is identified as the Goldstone boson of the broken sector. In spontaneously broken theories, the original symmetry of the Lagrangian is realized as a shift symmetry of the Goldstone bosons. We show that this is the case also here. The unbroken R=0 sector is completely different and has no connection to Einstein gravity.