New Research Suggests that the Universe is a Sphere and Not Flat After All

The universe is a seemingly endless sea filled with stars, galaxies, and nebulae. In it, we see patterns and constellations that have inspired stories throughout history. But there is one cosmic pattern we still don’t understand. A question that remains unanswered: What is the shape of the universe? We thought we knew, but new research suggests otherwise, and it could point to a crisis in cosmology.

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Being spherical is a property of the universe

Space / time / particles, then are bound by this behaviour, so does time come back onto itself at some point like space does, as well?

first my skull
then the earth
now they’re trying to tell me
the universe is round, not flat
¿
lol

Tau.Neutrino said:

New Research Suggests that the Universe is a Sphere and Not Flat After All

The universe is a seemingly endless sea filled with stars, galaxies, and nebulae. In it, we see patterns and constellations that have inspired stories throughout history. But there is one cosmic pattern we still don’t understand. A question that remains unanswered: What is the shape of the universe? We thought we knew, but new research suggests otherwise, and it could point to a crisis in cosmology.

more…

> In a new paper published in Nature, a team looked not at galaxies, but rather fluctuations within the Cosmic Microwave Background (CMB).

It’s a wonder they were able to publish. Results from the most accurate measurements of fluctuations in the CMB by the Planck spacecraft in 2018 showed that the universe is consistent with being flat.

For example: https://arxiv.org/abs/1807.06209

Hold on!

The means the universe is probably neither a sphere or flat, but has a negative curvature.
Negative Ω_K means hyperbolic space not spherical apace.

You can see why I don’t trust anything under 3 sigma, though. Observations at 2.3 sigma, 2.4 sigma, 2.5 sigma have a persistent habit of disappearing when better data becomes available. Equation 46a is only 2 sigma, ie a 5% chance from the data that the curvature of space is zero, which is quite a sizable probability.

And Occam’s razor suggests exactly zero. Why? Because a non-zero value would make the infamous fine tuning problem much worse. It’s bad enough trying to explain why dark energy and dark matter have close to the same strength. It would be practically impossible to explain away why all three of dark matter, dark energy and space curvature all have close to the same strength.

Already, some “anomalies” from the Planck data have vanished at similar sigma levels. https://sci.esa.int/web/planck/-/61396-planck-finds-no-new-evidence-for-cosmic-anomalies

If the universe was a sphere then that means light will eventually come back to its source but would that be true with inflation, would it forever be playing catchup

Cymek said:

If the universe was a sphere then that means light will eventually come back to its source but would that be true with inflation, would it forever be playing catchup

OK, I’ll nibble. This is one of those questions that looks easy on the surface, but requires careful thought.

It’s space-time that is curved, rather than space alone, and that means that in order to visualise it we need to look at a sphere in five dimensions, not just four dimensions. Hands up everyone who is good at visualising in five dimensions. Or skip the visualisation and go straight to the mathematics.

Am I right in thinking that even in a flat universe, galaxies are vanishing over the edge of the visible horizon? Why? Perhaps because as galaxies get older they get further from their zero-time origin, and further makes them more difficult to see?

If so, then what we would see in a spherical universe would be a tug of war between galaxies disappearing from view (at relatively short times) and the expansion of the visible horizon (due to curvature) at much longer times.

Then there’s the darn Olber’s paradox to consider. If we could see all the way around the universe, then the sky would become hugely bright and we would eventually fry to death.

Nope. I’m nibbling but I’m not biting. I don’t know that answer. You need to ask a professional cosmologist about this.