Our universe may not be flat:
Is Our Universe Hyperbolic? Hyperbolic geometry, with its narrow triangles and exponentially growing circles, doesn’t feel as if it fits the geometry of the space around us. And indeed, as we’ve already seen, so far most cosmological measurements seem to favor a flat universe.
But we can’t rule out the possibility that we live in either a spherical or a hyperbolic world, because small pieces of both of these worlds look nearly flat. For example, small triangles in spherical geometry have angles that sum to only slightly more than 180 degrees, and small triangles in hyperbolic geometry have angles that sum to only slightly less than 180 degrees.
Erica Klarreich, “What Is the Geometry of the Universe?” at Quanta
The reader who sent in this item writes to say, “I like Quanta. But they should be called out for this outrageous lie. (Lindberg, right again.)”:
There was a time, after all, when everyone thought the Earth was flat, because our planet’s curvature was too subtle to detect and a spherical Earth was unfathomable.
Erica Klarreich, “What Is the Geometry of the Universe?” at Quanta
Why would a spherical Earth be “unfathomable”? Once the Sun and the Moon were seen as spheres, whatever the universe as a whole might be like, it seems logical that Earth would be a sphere too. Otherwise, the traditional cosmos would have spheres revolving around a dinner plate. That is not aesthetically pleasing compared to spheres orbiting a central sphere. And our ancestors generally believed that there should be aesthetic order to nature.
The discovery that Earth was not the cosmic garbage dump at the centre of the universe provoked some angst, as we all know. But the idea that Earth was a sphere, well… surely it went down rather well?
See also: The beginnings of Western Science vs the Galileo myth. Lindberg: “It is little wonder, given this kind of scholarly backing, that the ignorance and degradation of the Middle Ages has become an article of faith among the general public, achieving the status of invulnerability merely by virtue of endless repetition.” And Bimbette Fluffarelli, talk show hostess, learned it sixteenth-hand at school…