Expansion, geometry, and gravity
In general-relativistic cosmological models, the expansion history, matter content, and geometry are closely intertwined. In this brief paper, we clarify the distinction between the effects of geometry and expansion history on the luminosity distance. We show that the cubic correction to the Hubble law, measured recently with high-redshift supernovae, is the first cosmological measurement, apart from the cosmic microwave background, that probes directly the effects of spatial curvature. We illustrate the distinction between geometry and expansion with a toy model for which the supernova results already indicate a curvature radius larger than the Hubble distance.
Additional Information© 2004 IOP Publishing Ltd Received 20 May 2004, accepted for publication 6 September 2004, Published 17 September 2004 This work was supported at Caltech by NASA NAG5-11985 and DoE DE-FG03-92-ER40701, and at Dartmouth by NSF grant PHY-0099543. http://arxiv.org/abs/astro-ph/0403003
Published - CALjcap04.pdf