Chronological parallax

I love the wierd stuff that is being learned in the areas of physics and cosmology these days. For some reason, I find it exhilarating and strangely comforting that reality is so different from what we experience day-to-day.

It must be the post-modern in me.

So, I was reading 'The Fabric of the Cosmos' by Brian Greene (a great author, btw) and he was discussing a truely mind-boggling implication of relativity. I'll try to explain it.

Relativity tells us that time proceeds differently for objects in motion. So, someone who goes on a round trip to Alpha Centauri at 99% of the speed of light will age less than those who stay behind.

This is bizarre enough on its own, but the really wierd thing Brian was presenting was that a result of this relativity is that what I experience as 'now' at any given moment of time during the trip would be different for that traveler. Ok, well, I guess that follows. But a deeper implication is that the time discrepancy exhibits a sort of parallax depending on how far away the objects in motion are from each other. So, an object that is moving with respect to me and is far away from me will experience the discrepancy being amplified by the distance. Playing this out, our Alpha Centauri traveler would experience the discrepancies between his or her 'now' and ours as growing as he or she traveled away. And when he or she reached Alpha Centauri, it might be that he or she would, looking back at us, detect 'now' for us being quite a bit in the past, or even in the future depending on the direction of the motion. As in, we might not be born yet or we may have been dead for 100 years!

This parallax is made greater by the relative motion of the two objects and their distance and could conceivably cause one object to see the 'now' of the other object being any time in the past, present, or future of that other object.

This is so incredibly bizarre.

This means there is no universal, absolute 'now'.

It also means that the notion that 'now' is all that exists is false! What is past, present and future depends on the reference (with respect to position and motion) of the object experiencing the 'now'. 'Now' has no special meaning or status. All of time can be 'now' depending on relative motion and distance.

I can hardly get my mind around it. But it sure is fun trying.