Fold testament: what shape is the universe?
来源：未知 作者：蓝铡袷 时间：2019-03-15 08:13:00
By Stephen Battersby As big questions go, it’s hard to get much bigger. Does space go on forever? Some cosmologists suspect not. Rather than stretching off into infinity, space might be a much smaller, more manageable place. If we could cross the cosmos in a spaceship, then like sailors circumnavigating the globe, we might find ourselves back where we started. Unlike the Earth, though, the universe does not have to be round. Its true shape is still a mystery. Is it flat like a sheet of paper? Is it curved? Is it tied in a knot, tangled by gravity at the very beginning of the big bang? Does it even make sense to talk about the shape of something as complicated as the universe? After years of detective work, cosmologists are at last beginning to get a little closer to some answers. In their quest to discover the shape of things, they have already explored to the edge of the observable universe – and they are even hoping to go beyond. It is easy to visualise the shape of ordinary objects because you can look at them from the outside. You can pick up a cup, view it at different angles, feel its curves and surfaces, poke a finger through the handle. But we can’t do this with the universe because we’re stuck inside it – in fact, according to some definitions, it is all that exists. There are, however,