Expert: James Gort - 8/19/2011

Question
Is the Hobble observation conclusive evidence that our universe is expanding?

Would there be an observable difference if space was contracting, which would require matter to perpetually transition through space, instead of expanding?

Consider this scenario. Instead of the popular analogy of placing dots on the surface of a balloon and inflating it, what if the balloon was filled with galaxies and a hole was poked in the balloon, allowing the galaxies to exit the balloon one at a time. Given enough time for the exiting galaxies to attain an orderly orbit about the exit point, would the velocities of such galaxies be proportional to their distance from the exit point (vertex)? In this imaginary system, how would an observer placed in each galaxy perceive light from the other galaxies?

Answer
Hi Luis,

Yes, I think there would be an observable difference, but let me go through your scenario:

If a hole was poked in the balloon, it would contract, and that would be your analogy of "space contracting". But galaxies would be allowed to exit through the hole. From there, I'm a bit lost, because this model would seem to have galaxies exiting the known universe (is not the balloon analogous to the universe?). That said, I don't think the velocity of the exiting galaxies would be proportional to their distance from the exiting point - it seems to me, the velocity would be constant, unless they found themselves on the surface of a second balloon, and then the velocity would be proportional to distance from the hole. But this would complicate things unnecessarily, IMHO.

But since you're obviously thinking about alternative explanations of observations of galaxies' velocities (which many people conclude is due to an expanding universe), I want to remind you that the velocity-distance relation, which MAY imply a "Big Bang", 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.

So please keep an open mind on the subject of an "expanding universe". The jury is still out.

Cheers,

Prof. James Gort