[Todos] Seminario extraordinario IAFE Jueves 1 de Marzo, 15 h

[Pablo Balenzuela]

Estimados/as colegas,

les transmito la información del seminario que está organizando César 
Bertucci en el IAFE el jueves de esta semana y que puede ser de vuestro 
interés:

En el marco de la reunión del Laboratorio Internacional Asociado (LIA) 
en procesos de plasma alrededor de la Tierra y magnetósferas planetarias 
(MAGNETO) entre CONICET y CNRS tenemos el gusto de invitarlxs al 
seminario de Sebastien Galtier (Profesor e investigador en Université de 
Paris Sud y Ecole Polytechnique Palaiseau) sobre el tema:

Turbulence of weak gravitational waves in the early Universe

We are currently experiencing a revolution in astronomy with the
multiplication of direct observations of gravitational waves (GWs). What
about the theoretical study of GWs? We have studied analytically [1] the
non-linear behaviour of a random set of weak GWs. Such a situation can be
expected in extreme cases such as the black hole environment or the very
primordial Universe around 10-36s. In this seminar I will present the weak
GW turbulence theory and give the analytical solutions which correspond to
a double cascade of the space-time metric. The direct cascade is limited
by the Planck scale below which the general relativity equations become
invalid. Interestingly the inverse cascade is explosive with in principle
the possibility to excite fluctuations from the forcing wave-number kF to
k=0 in a finite time. However, this mechanism ends up at the scale where
the GW turbulence becomes strong. I will show numerical simulations to
illustrate the cascade mechanism and get additional information. I will
eventually discuss the possible link between the inverse cascade and a
mechanism of expansion of the Universe.

[1] S. Galtier & S.N. Nazarenko, Turbulence of weak gravitational waves in
the early Universe, Physical Review Letters 119, 221101 (2017).


El seminario tendrá lugar en la sala de conferencias del IAFE el Jueves 
1 de Marzo a las 15h
Lxs esperamos !

-- 
         Dr. Pablo Balenzuela
	Departamento de Fisica, FCEyN,
	Universidad de Buenos Aires,
	(1428) Ciudad Universitaria,
	Ciudad de Buenos Aires, Argentina.
	TE +54 11 5285 7545
	Fax +54 11 4576 3357
	email: balen en df.uba.ar
	Webpage: http://www.df.uba.ar/users/balen/blog