I've never really understood the fuss about the Theory of Relativity. Essentially Albert Einstein took the idea of 3D and thought, "What would this look like over time?"
Time is the obvious fourth dimension. What complicates time — I guess this is the bit that I would call poetry or Proust and Einstein would call physics — is our experience of it. We understand that time passes because coasts erode, buses leave without us, and because we used to be children and will die.
What we find much harder to understand and explain is that a single moment can feel as if it has expanded to infinity, and conversely, that we have no memory of our babies, now seven, now ten, now teenage, now adult, now gone. They rush through our fingers, and leave photos behind, but we cannot remember them as they were.
Our children are like palimpsests — my daughter boils down to a steady stare, over the edge of her nasty plastic cot in UCH hospital, the night after I delivered her. Days passing like sand have sedimented that stare, fossilised it for me, and add up in the hourglass to a long-legged colt with the same huge eyes and all-seeing gaze.
In that sense, relativity takes on a gut-churning, mind-addling meaning: being someone's relative means being relative to them, means being two trains passing each other at different speeds.