Where are the Walls?

Understand

The reported spatial variation in the fine-structure constant at high redshift, if physical, could be due to the presence of dilatonic domains, and one or more domain walls inside our horizon.

• An absorption spectrum of an object in a different domain from our own would be characterized by a different value of alpha.
• We show that while a single wall solution is statically comparable to a dipole fit, and is a big improvement over a weighted mean (despite adding 3 parameters), a two-wall solution is a far better fit (despite adding 3 parameters over the single wall solution).
• We derive a simple model accounting for the two-domain wall solution.