This Quanta Magazine article (below) is a helpful visual recap of whether the cosmos is “flat” or not. Does the cosmic landscape of stars and galaxies extend / expand in all directions like an endless piece of paper? Or another “flat” geometry – “by cutting a chunk out of Euclidean space and gluing it together.”
Or does space curve in some way in higher dimensions? (“By gluing up a suitable chunk” of a 3-sphere, for example.)
What’s the evidence against a flat universe? The paths of “straight” lines and angles in triangles might tell.
• Quanta Magazine > “What Is the Geometry of the Universe?” by Erica Klarreich (March 16, 2020)
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.
We can ask two separate but interrelated questions about the shape of the universe. One is about its geometry: the fine-grained local measurements of things like angles and areas. The other is about its topology: how these local pieces are stitched together into an overarching shape.
3 thoughts on “Does the universe have a shape?”
Here’s Ethan Siegel’s take on Olbers’ paradox.
Medium > “Why Is The Sky Dark At Night?” by Ethan Siegel (Aug 27, 2019) – The darkness of the night sky was a mystery for generations of humans. Here’s the reason why.
Progress in mapping the observable universe … more galaxies, more detail … more supercomputers …
• Space.com > “Scientists just mapped 1 million new galaxies, in 300 hours” by Brandon Specktor (Dec 4, 2020) – All-sky surveys usually take years. This one took weeks.
• Science Alert > “Astronomers Just Mapped 1 Million Previously Unknown Galaxies, And You Can Take a Tour” by Aidan Hotan, The Conversation (1 December 2020)
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