My apartment has relatively high ceilings because it’s an old building. The sunlight comes sideways through my windows. If I don’t leave my apartment, the world might appear like a big pancake (ie, flat). It’s an optical illusion. Several centuries ago, sailors assumed Earth was flat as they didn’t experience curves.
The latest scientific assumption is that the Universe is flat (eg, Ethan Siegel in Big Think). I think, feel and believe that this assumption will ultimately be invalid, although evidence may take centuries. Why?
Given “the odd structural similarities between the human brain and the Universe” (eg, Nautilus-2017, Frontiers in Physics-2020, ScienceAlert-2020), it should be unlikely that the Universe would be flat while the human brain is roundish. Perhaps our brain is roundish given its constraints, being the skull.
A flat Universe also contradicts the shape of planets and stars. Why would all planets and all stars be round while the Universe is flat?
Moreover, a flat Universe should not match the Big Bang “explosion”. A flat universe could only happen when there is a “ceiling” and a “floor”, like in my apartment. Else, you would expect a roundish Universe. A flat Universe should imply that its size is limited due to certain “constraints” (eg, “ceiling”, “floor”).
There’s another explanation for a flat Universe. Perhaps, our Universe might “drift” on something else (eg, “water”). In such a case, a flat Universe would be like a huge oil stain drifting on ocean water.
The difference between flat and round is the number of dimensions (ie, 2 vs 3). The human eye can only see 2 dimensions, length and width (eg, any photograph). Our brain uses our 2nd eye to simulate depth (ie, 3-dimensional).
I’m not arguing that Ethan Siegel is wrong. No. However, if he is right about the shape of the Universe, there should be immense consequences, like limited dimensions, and possibly also the existence of something else that is bigger than our Universe. That would be far more important.
The song below is about non-existent Dutch mountains. We do have some hills, however. Essentially, the Netherlands is “flat”. I doubt the Universe is.
Note: all markings (bold, italic, underlining) by LO unless in quotes or stated otherwise.