What interests me is the subject of time dilation and how inertial frames come into play. (This might be a topic worth touching on in a podcast.) For example, we have two people at rest and then person B accelerates away from person A. Seems to me that from each of their perspectives the other should be running in slow motion time. Correct? At some point person B stops and accelerates back towards person A. My understanding is that A will be much older than B, but why? If there is no absolute reference then from B could consider himself to be stationary and from his perspective A may be moving away from him.

I know that there are reasons for the accepted conclusions but I don't have a good handle on them.