In the Wheeler-Feynman picture when the retarded wave is absorbed at some time in the future, a process is initiated by which canceling advanced waves from the absorbers erase all traces of advanced waves and their ``advanced'' effects, thereby preserving causality. An observer not privy to these inner mechanisms of nature would perceive only that a retarded wave had gone from the emitter to the absorber. The absorber theory description, unconventional though it is, leads to exactly the same observations as conventional electrodynamics. But it differs in that there has been a two-way exchange, a ``handshake'' across space-time which led to the transfer of energy from emitter to absorber.
This advanced-retarded handshake is the basis for the transactional interpretation of quantum mechanics. It is a two-way contract between the future and the past for the purpose of transferring energy, momentum, etc, while observing all of the conservation laws and quantization conditions imposed at the emitter/absorber terminating ``boundaries'' of the transaction.
The transaction is explicitly nonlocal because the future is, in a limited way, affecting the past (at the level of enforcing correlations). It also alters the way in which we must look at physical phenomena. When we stand in the dark and look at a star a hundred light years away, not only have the retarded light waves from the star been traveling for a hundred years to reach our eyes, but the advanced waves generated by absorption processes within our eyes have reached a hundred years into the past, completing the transaction that permitted the star to shine in our direction.