Flat or Round Universe?

What Shape Is the Universe? A New Study Suggests We’ve Got It All Wrong

Natalie Wolchover

A provocative paper published [in 2019] in the journal Nature Astronomy argues that the universe may curve around and close in on itself like a sphere, rather than lying flat like a sheet of paper as the standard theory of cosmology predicts. The authors reanalyzed a major cosmological data set and concluded that the data favors a closed universe with 99% certainty — even as other evidence suggests the universe is flat.

Here's an article from approximately a year later, Nov 2020 ->

The Size, the Shape, and the Idea of the Universe

By Don Lincoln, Ph.D., Fermi National Accelerator Laboratory

We know that the universe is 13.7 years old and the light that can be seen by us from the early moments of the universe is the radio hiss. That is the farthest we are able to see. So we can call it the visible universe. This term is used to differentiate between the universe we can see and the universe as a whole. But are we sure about the size and the shape of the universe that is visible to us?

We are not sure if the space was flat or curved at this early time. If the universe was curved, maybe there were many such small volumes having deformed shapes, maybe a cluster of volumes on the surface of the sphere. And if space were flat, there could be an infinite number of such volumes in an infinite space. In any case, space started expanding very quickly. The expansion was so rapid that if initially space was curved the expansion was enough for us to be unable to see any residual curvature. And if it were flat, it stayed that way.

Now, what was a tiny volume has presently become an enormous volume that is 46 billion light-years in radius or 92 light-years across. We are not sure if that is just one of an infinite number of volumes. Also, we are not sure of how the universe actually began. It could be different. There are many other ideas regarding that. One of those is of many universes floating in a higher-dimensional space like ribbons, ramming into each other and heating each other up, and looking like the big bang. And some of those are simpler ideas.

So no resolution as yet it seems...