There's an article about Loop Quantum Gravity in this month's Scientific American, and I have a quick question. They assume space itself is made out of "atoms" with definite size (Planck's length if I'm not mistaken). So how exactly does it work with the expansion of the Universe? Do these "space-atoms" move away from each other? Then what would be the stuff between them (non-space)? Or are there more "space-atoms" being created? Or do the "space-atoms" themselves get bigger? In that case, it's unclear to me against what their increasing size can be judged since they themselves are space. Thanks.