Expert: James Gort - 12/9/2011

Question
I know that the universe is expanding at an accelerating rate. Will the speed of the expansion ever reach the speed of light?
Do we know how fast we are expanding and at what rate the speed is increasing? Can we project when we would reach the speed of light or go back and determine how long or how far we've traveled?

Answer
Hello Jim,

First, I know some Nobel Prizes were awarded for the "discovery" of the accelerating universe. So I may seem to be a heretic, but I don't believe there's enough evidence of this "acceleration" to attempt to answer your questions.

First, the redshift itself does not necessarily relate to distance (as the "Hubble Law" would have us believe). Although the velocity (i.e., redshift) / distance relation (leading to the Big Bang implication) is believed to be valid by the majority of cosmologists, it is by no means universally accepted. The "Big Bang", based on Hubble's velocity-distance relation and the microwave background radiation, is very much still a theory, and there are alternative theories. Some observations do not support an expanding universe or the Big Bang. There are several references concerning this, but perhaps the most authoritative person is Halton Arp, a leading astronomer and researcher on galaxies, who wrote "Seeing Red". That book is highly recommended to get an alternative view.  Or read "A Different Approach to Cosmology" by Hoyle, Burbidge, and Narlikar.  Another great book which gives a scientific view on how the universe has always been in a steady state.  

But let's assume the above cosmologists are WRONG and the velocity-distance relation is true. Even then, the "accelerating universe" (based on the standard candle of distant supernovae) may not be interpreted correctly by the Nobel winners. For instance, Christos Tsagas, an astrophysicist at the Aristotle University of Thessaloniki, Greece argues that the universe IS NOT accelerating, but decelerating (the apparent acceleration is due to our Galaxy's motion in space). A couple of papers you might want to see are "Peculiar motions, accelerated expansion, and the cosmological axis", PHYSICAL REVIEW D 84, 063503 (2011) and "Large-scale peculiar motions and cosmic acceleration", Mon. Not. R. Astron. Soc. 405, 503–508 (2010)- both available at http://www.astro.auth.gr/~tsagas/papers1.html.

So as you can see, there are many open questions. We don't know enough to say whether the universe expansion is happening at all, let alone the rate of expansion. Your questions may eventually be answered, but certainly not today. And anyone who says otherwise is just wrong. Without question.

Hope that helps.

Cheers,

Prof. James Gort