About Eternal Inflation and Spacetime Bubbles

[Curious6]

I have read a lot about eternal inflation and as I understand it Guth and others are now arguing that once inflation has started, it is an ongoing process. However, my question is, once inflation had finished in one Universe and inflation had started somewhere else, wouldn't the expanding inflationary domain soon collide with the Universe that had already inflated? I mean, what stops the spacetime bubbles of colliding with each other?

 

[Garth]

Perhaps they pass through each other without knowing it?
The collisions you imagine are in space-time, however each such bubble universe would have its own space-time continuum; what the ensemble of all such universes are embedded in is anyone's guess!

Garth

 

[ray b]

if the other bubbles pull on ours
then you have the power source of the inflation
simple gravity but from outside our bubble

 

[Chronos]

Here is an interesting paper on that subject by Sean Carroll:

http://arxiv.org/abs/hep-th/0410270
Spontaneous Inflation and the Origin of the Arrow of Time
"We suggest that spontaneous eternal inflation can provide a natural explanation for the thermodynamic arrow of time, and discuss the underlying assumptions and consequences of this view..."

Here is a recent followup on that paper:

http://arxiv.org/abs/gr-qc/0505037
Does Inflation Provide Natural Initial Conditions for the Universe?