Recombination (decoupling of light)
for electrons to become
bound to atoms
wavelengths interact with
© 2005 Pearson Prentice Hall, Inc
An inflationary period solves the horizon problem by recognizing that the inflation took two points that were causally connected could be rapidly dragged apart if the expansion was faster than the speed of light. The laws of physics say that nothing can travel faster than the speed of light. To be more precise, no signal can travel faster than light speed. This doesn't mean that the whole universe could not expand faster than light speed, since it is space that is expanding, not a signal propagating across space. In the diagram above, points A and B start out close enough together that they can be causally related - they can affect each other because light can pass between them. After inflation rapidly expands space, A and B are no longer causally connected, but as the universe further expands they are both within sight again. They look similar because they were causally connected before inflation happened.