The Sky in 350 Billion Years

re  -  8:00
But the thing is, you wouldn't know if the space between atoms is expanding, or rather, you wouldn't know if the expansion of space is causing the space between atoms to expand, since any attempt to measure these spaces would be subjected to the same expansion of space. What I mean is, if you were using a 30cm/ 1 foot ruler to measure the space between atoms (just as an example. I mean, let's pretend that they're giant, SUPER-atoms). Now if the ruler was constant, then you'd be able to measure any expansion of the space between atoms. However, if your ruler was also expanding at the same rate as the space between atoms, then it would appear that the space between atoms has remained constant, even though it's been expanding at a rate that is unmeasurable, due to the very expansion that's causing... the... err... expansion!!!