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SUMMARY:Unknowns of energy concentrating phenomena - Prof Seth Putterman\,
  UCLA 
DTSTART:20170428T130000Z
DTEND:20170428T140000Z
UID:TALK71922@talks.cam.ac.uk
CONTACT:Hilde Hambro
DESCRIPTION:The flow of energy through a fluid or a solid can lead to dyna
 mical motion that is dominated by nonlinear processes that The path to equ
 ilibrium is not controlled by entropy production. Although entropy increas
 es with every time step\, dynamical motion can be dominated by nonlinear p
 hysical process which spontaneously concentrate energy density.  In sonolu
 minescence a bubble concentrates the energy of a traveling sound wave by 1
 2 orders of magnitude to create picoseconds flashes of blackbody radiation
  that originate in a new state of matter.  When surfaces are brought into 
 and out of contact they exchange charge: a process call tribo-electrificat
 ion. This phenomenon can be so strong that the power applied to peel  stic
 ky tape is efficiently transduced into a flux of high energy electrons\, a
 nd x-ray photons that take a chest xray in a few seconds. For a  ferroelec
 tric crystal\, instabilities in the phonon spectrum lead to a spontaneous 
 polarization that for Lithium Niobate reaches 15.million volts per cm. The
  temperature dependence of this field can be  used to build a neutron gene
 rator based on the fusion of deuterium nuclei. These phenomena challenge a
  reductionist approach to the theoretical physics of emergent phenomena. T
 he degree to which the energy density of a continuous system can be concen
 trated by off-equilibrium motion has not been determined by theory. For so
 noluminescence we do not know if the parameter space includes a region whe
 re an extra factor of 100 in energy density makes it possible to realize t
 hermonuclear fusion. For triboelectrification we do not have an ab-initio 
 theory of charge transfer. And for ferroelectrics we do not have an ab-ini
 tio theory of the limits of spontaneous polarization which can be designed
 .  
LOCATION:Oatley Seminar Room\, Department of Engineering
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