I recently came across this paper on arXiv.org(adsbygoogle = window.adsbygoogle || []).push({});

http://arxiv.org/abs/astro-ph/0310808

Expanding Confusion: common misconceptions of cosmological horizons and the superluminal expansion of the Universe

Authors: Tamara M. Davis, Charles H. Lineweaver

Comments: To appear in Publications of the Astronomical Society of Australia

We use standard general relativity to illustrate and clarify several common misconceptions about the expansion of the Universe. To show the abundance of these misconceptions we cite numerous misleading, or easily misinterpreted, statements in the literature. In the context of the new standard Lambda-CDM cosmology we point out confusions regarding the particle horizon, the event horizon, the ``observable universe'' and the Hubble sphere (distance at which recession velocity = c).

We show that we can observe galaxies that have, and always have had, recession velocitiesgreaterthan the speed of light. We explain why thisdoes not violate special relativityand we link these concepts to observational tests. Attempts to restrict recession velocities to less than the speed of light require a special relativistic interpretation of cosmological redshifts. We analyze apparent magnitudes of supernovae and observationally rule out the special relativistic Doppler interpretation of cosmological redshifts at a confidence level of 23 sigma.

- end abstract -

I was wondering if someone familiar with SR and GR could briefly take a look at the main points in this paper. Is this paper spot on? It really makes me think that I have been misled be over-simplifications in previous texts I have read, and the authors state that many scientists themselves are confused about some basic ideas. Their paper seems Ok to me, but I'm not an authority on this (or anything, I suppose.) I'd appreciate it if you could give me your thoughts.

Thanks,

Robert

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# Common misconceptions of cosmological horizons and superluminal expansion

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