[seminar] DANAS: T. Prokopec, Graviton backreaction in expanding ...

[Kresimir Kumericki]

Prirodoslovno-matematicki fakultet
FIZICKI ODSJEK 
Bijenicka c. 32, Zagreb, Hrvatska

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                     SEMINAR  TEORIJSKE  FIZIKE
(Zajednicki seminari Fizickog odsjeka PMF-a te Odjela za fiziku IRB-a)

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Graviton backreaction in expanding spacetimes and the cosmological
constant problem

dr. Tomislav Prokopec

Institute for Theoretical Physics, University of Utrecht, Netherlands

Datum: 9. srpnja 2008. (srijeda)
Vrijeme: 15 sati c.t.
Mjesto: PMF, Fizicki odsjek, Bijenicka c. 32, F-201


Sazetak:

  We consider the one loop backreaction of gravitons and massless scalar
matter in expanding space times. We calculate the backreaction in space
times whose scale factor expands as a power law in time, and show that
the backreaction becomes large for certain values of the power.

In particular we consider a universe filled with relativistic matter and a
cosmological constant.  Our calculations suggest that at late times the
quantum effects compensate the cosmological constant, such that the
late-time Universe asympotes a matter like universe with an expansion rate
that approaches zero.

2008-07-07 

Voditelj seminara:
dr. Kresimir Kumericki (kkumer at phy.hr)