Acc. to general relativity time runs slowly near a massive body.So, i have a question bothering me from some time that if time for every body/object in universe runs at a different rate then how can we determine the age of universe i.e. 13.72 billion years. Near a blackhole as time runs slowly, age of universe would be much much less.Infact,ever body/object in universe would have different age of universe acc. to it. And if we really want to calculate universe present age we should put a upper limit to it's age by determining the time passed in empty space from big bang which is away from gravitational source (as time passes the fastest here) and a lower limit by the oldest and massive blackhole in universe as time there would have passed the least i.e. the age of universe from it's point of view would be even less than 0.5 billion years. Hope,i am right!