Hi Fred.

The idea of us being in a less dense "bubble" is not new. David L. Wiltshire (http://arxiv.org/abs/gr-qc/0702082) has postulated that the apparent accelerating expansion rate is due to the difference in 'cosmic time' in our 'void' relative to the more dense areas around us. I recall that has he has met with some valid criticisms, which obviously does not mean that he is completely wrong.

As difficult as 'dark energy' is to cope with, it is still the only hypothesis that fits the majority of observations rather well. Despite this, I'm one of the many hoping that a hypothesis with a 'better fit' will appear on the scene. I'm however not very optimistic about the 'shell theorem'.

Regards,

Burt Jordaan (www.Relativity-4-Engineers.com)