To meet someone who lives somewhere else, I have to specify the place and time.
Like the Med building.
Along Grattan Street.I would meet that person if my location along these 4 axes (3 space, 1 time) intersect. I wouldn't if I turn up at 9pm; well, maybe I would, but with a different person.
Corner of Elizabeth Street (or Royal Parade).
(Credits to Brian Greene, who illustrated this sort of example in The Elegant Universe.)
And something about time and about the Beijing 2008 Olympics.