Paper Information

Journal:   JOURNAL OF THEORETICAL AND APPLIED PHYSICS (IRANIAN PHYSICAL JOURNAL)   2009 , Volume 3 , Number 3; Page(s) 31 To 36.
 
Paper:  WILL MODIFICATION OF THE EINSTEIN FIELD EQUATIONS HAVE COSMOLOGICAL IMPLICATIONS?
 
Author(s):  TEHRANI NASAB S.*
 
* PHYSICS DEPARTMENT, ROYAL HOLLOWAY, UNIVERSITY OF LONDON, EGHAM HILL, EGHAM, SURREY TW20 0EX, UK
 
Abstract: 

The field equations of general relativity can be derived from a stationary action principle. But these equations are not unique; they may be modified by adding, for example, a second order curvature term to the gravitational action. The inclusion of one such a small corrective term leads to a set of equations with four new terms (which involve up to the fourth derivative of the scale factor). When we consider the case of a radiation-filled universe, it turns out that the effects of these new terms cancel if we adhere to the Robertson-Walker mertic (which has built into it the observed features of homogeneity and isotropy). We find R(t)=Ö1(1+ltp) and R(t)=bÖt to be equally valid solutions of the modified field equations (where R(t) is the scale factor and b and l are constants; l is very much smaller than b; p =-1). Only the first and second derivatives of R turn out to be non-vanishing. The Robertson- Walker cosmology survives our modifications even for times that are long compared with the Planck time.

 
Keyword(s): GENERAL RELATIVITY, STATIONARY ACTION, CURVATURE TERM, ROBERTSON-WALKER METRIC
 
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