A lesson in cosmology

In cosmology, it is usual to talk of three types of universe. They are hard to envisage, because they are all three-dimensional and change with time, so it is is generally easier to hold a two-dimensional picture in one's mind, and leave the third and time dimensions to the mathematicians. The three are: ones that are flat, like a sheet of paper; ones with positive curvature, like a globe; and these with negative curvature, often likened to a saddle shape, curving in two opposite directions. Time is then "pictured" by thinking of the shapes as elastic, then being pulled equally in all directions so that if we draw little galaxies on them they will begin to move apart.

Visualizing the mysterious open Universe

What force pulls them apart? I said it was hard to imagine – indeed the force that started it all is itself described as "unimaginable" in all its attributes; vanishing smallness, infinite temperature, infinite density, and a time so small it is thought that no other time can ever be shorter. Cosmologists sum it up as the Big-Bang, though only the Universe itself could have heard it. Now imagine all that going on in three-dimensions, and the mind's eye fails. It really is easier to think of it as a great saucer carried by elephants. And how many people even handle saddles these days?

Not dead yet

We have walked the graveyard,
touched the tombstones
felt the putrid air of death
wept at the nameless wreath.
Today, we have rejoined life,
drank the sweet red wine,
eaten of the forbidden fruit
breathed the spring like autumn air,
it is our world
and we are still here.

by Annie Elliott

We may as well describe the open universe as the contrary curves of a woman's waist, usually hidden from view, everywhere quite mysterious, yet smooth and continuous. Ann is my Universe. Just don't describe the galaxies as wrinkles on the surface of time, moving apart as the curves expand, or you'll get into serious trouble!