You’ve probably heard of the “observable universe”, or all places in the universe we can currently observe, which is essentially defined by the speed of light. Here’s a new one for me: the “affectable universe
”, or the areas of the universe that we can affect by way of sending light. BUT because the universe is expanding, the affectable universe is shrinking
at the same rate that observable universe is expanding
. As time goes on, we can see ever more of (the past of) the universe while our ability to impact the universe is ever more constrained.