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FIZIKA B 18 (2009) 2, 81-86
 
LETTER TO THE EDITOR
LYRA COSMOLOGY IN D=n+4 DIMENSIONS: THE INTERESTING CASES OF n
³ 6 AND n £ 104
RAMI AHMAD EL-NABULSI
Department of Nuclear and Energy Engineering,
Cheju National University, Ara-dong 1, Jeju 690-756, South Korea
E-mail address:
[email protected]
Received 28 March 2007; Revised manuscript received 25 February
2009
Accepted 17 June 2009 Online 13 July 2009
Exact solutions of the Einstein's field equations in Lyra geometry in D=4+n
dimensional spacetime with time-increasing G and decaying cosmic fluid and
density are obtained and discussed in some details. We suggest the
phenomenological dissipative law b2 µ H/t for the square of the non-zero
component of the displacement vector field fA. H is the Hubble parameter in the extra-dimensional spacetime
metric. It has been observed that the cases n ³ 6 are within the observational limit, the four-dimensional spacetime is in the
stage of accelerated expansion, while the extra-dimensions are contracting in
time.
PACS numbers: 04.20.Jb; 98.80.Hw
UDC 52-423, 524.83
Keywords: higher-dimensional cosmology, gravitational constant, Lyra
geometry, effective pressure
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