May 31, 2022
FLAT AND YOUNG:
The Universe is flat. Here's what that teaches us.: In theory, the fabric of space could have been curved in any way imaginable. So why is the Universe flat when we measure it? (Ethan Siegel, 5/31/22, Big Think)
What is the shape of the Universe? If you had come along before the 1800s, it likely never would have occurred to you that the Universe itself could even have a shape. Like everyone else, you would have learned geometry starting from the rules of Euclid, where space is nothing more than a three-dimensional grid. Then you would have applied Newton's laws of physics and presumed that things like forces between any two objects would act along the one and only straight line connecting that. But we've come a long way in our understanding since then, and not only can space itself be curved by the presence of matter and energy, but we can witness those effects.It didn't have to be the case that the Universe, as a whole, would have a spatial curvature to it that's indistinguishable from flat. But that does seem to be the the Universe we live in, despite the fact that our intuition might prefer it to be shaped like a higher-dimensional sphere.
Posted by Orrin Judd at May 31, 2022 12:00 AM