Age of the universe -- absolute or relative? I have a question. Consider twin physicists Al and Bert who devise a new method (far better than measuring cosmic microwave background) to determine the age of the universe. They do so to an extraordinarily high degree of precision – stating it in seconds to many, many decimal places. Having done so, they synchronize two clocks to the determined age of the universe and allow them to continue ticking off time from that point on. After winning the Nobel prize for this work, Al uses his prize money to build a near light speed space ship and he heads off, with his clock, to travel the cosmos at high speed, accelerating and changing directions along the way, coming in close proximity to black holes and other high gravity bodies, and eventually returning to earth. Of course, the time elapsed for Al will be less than the time elapsed for the earthbound Bert, so when they compare clocks they show different times. So, my question: Now how old is the universe? I suppose my larger question is whether the age of the universe is an absolute or relative measure. And beyond that, is it meaningful to think about the measure of elapsed time since the beginning of the universe in the relatively flat space-time we inhabit in the same way as elapsed time in the earliest moments after the big bang when all space-time was more highly curved?