The problem is now. The endless stream of nows, not discretizeable, so the computers can't do anything with them. Sure there are floating point numbers, and double precision, but there are limits to these things. The problem is precisely beyond those limits.
It used to be no one could talk about it until a gentleman sorted out a few centuries worth of thought and came up with infinity. It had been around forever, of course, but it needed rules to work. Otherwise you're just talking about a mess and that is far from the stream, the endless endlessness flowing through you, now and now and now now now now now
But the computers still can't model it, and neither can the typefaces looking at you, all pupil, from the whitespace of the page. Discrete words -- the best you can do it arrange them so they point, like a finger at the moon. But every dog knows how that one goes. He'll just look at your hand, tail wagging. Doesn't seem to be bothered by the problem at hand. Then again, he knows he did something wrong when you come home and he's slinking around the silent stain on the carpet. How? Somewhere in his mind -- now the preferred term is brain -- he held on to a piece of a now, even as it passed several hours ago downstream while you and Carol were at dinner talking about the relative merits of slow vs. fast moving zombies in film. Remember that? (You agreed faster = scarier and now that too is downstream, bobbing with the pee and the release of one canine's unbearable urges).
How do you remember? It can't be caught, yet somehow it stays, sometimes horribly permanent, sometimes like little clearings in the wild of your mind. Brain. Apparently what infinity needed was a set of relationships to something not infinite. That's what he figured out. That's where you come in.