In my prior Blog, we have seen roughly how the 'colliding branes cosmic model', or 'ekpyrotic model' works. Two parallel branes, which can be thought of as 3-dimensional 'sheets' in 4-dimension space, collides and creates a 'hot Big Bang', in one (or both) branes, without having to start from a singularity. For visualization, the branes are usually pictured as just flat 2-d sheets, living in 3-d space. The 2-d surface represents normal 3-d space and the third dimension represent hyperspace, where many branes may live, without us being able to observe them directly.

Now this is very similar to the old 'cosmic balloon', where the surface represents all three dimensions, with the third dimension representing the fourth space dimension (sometimes also called 'hyperspace'). Now what if we give this balloon a double skin with a tiny gap between? Shown here is the original cosmic balloon (black surface, called 'Brane A') and the extra skin as just a green circle (representing a similar 2-d brane, 'Brane B').

If we can devise something that sits in the gap and give a 'push' and a 'pull' to each brane, can we have an 'ekpyrotic cosmic balloon'? Similar to the original cosmic balloon, where we simply programmed a pump to inflate the balloon to the correct cosmic expansion law, I suppose we can have an extra pump that just pumps the gap.

Recall that we tried in vain to design an 'engineering solution' for a self-inflating balloon that have all the characteristics of the standard cosmic model. In the end we had to revert to a brute force method of just pumping at the right rate for the time we were in. I do not suggest that we try that exercise again, so we should perhaps just pump the gap at the required rate as well. It is important to have two pumps, though, because the dynamics of the inner balloon may be different from the dynamics of the outer balloon.

The benefit of the cosmic balloon analogy is that it makes some concepts easier to visualize. Proof of that is in the five or so 'applications' of the cosmic balloon that I posted following the "perfect cosmic balloon" thread. I thought this effort may perhaps make colliding branes also tiny bit easier to comprehend and to contemplate the effects.

Like the original 'design', this will probably also be a 'work in process', not a product; so, if you are interested in the progress, subscribe to this thread; or even better, collaborate in the project "Design the Perfect Ekpyrotic Cosmic Balloon".

-J

PS: I did not intend to post this in this week, but made an error in the delayed posting date, hence it appeared yesterday as a 'stub'. Sorry about that.