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Flat Universe
StarDate
English - June 13, 2024 05:00 - 2 minutes - 1.06 MB - ★★★★★ - 205 ratingsNatural Sciences Science astronomy telescope mcdonald observatory npr sandy wood stargazing sky constellations meteor showers eclipses Homepage Download Apple Podcasts Google Podcasts Overcast Castro Pocket Casts RSS feed
Our universe appears to be “flat” — like a sheet of paper stretching to infinity. If so, that would mean it’s finely balanced — a sort of “just right.”
Albert Einstein’s theory of gravity, known as General Relativity, allows the universe to assume one of three basic shapes. One shape is “closed” — like a sphere. In such a universe, two lights beamed out parallel to each other eventually would circle all the way around to their starting point.
Another possible shape is “open” — curved like a saddle or a really big Pringles chip. The light beams in such a universe would move away from each other for all time.
Finally, there’s a “flat” universe. Two light beams would remain parallel to each other forever — never spreading apart or coming together.
The actual geometry is dictated by the density of the universe — how much matter is packed into its space. In a closed universe, there’s enough matter for its gravity to cause the universe to collapse. An open universe would expand forever. And a flat universe would be balanced — neither collapsing nor expanding without end.
So far, the evidence supports a flat universe, although the matter isn’t completely settled.
Not surprisingly, it’s all pretty complicated. The flat universe is flat in three dimensions — after all, we see galaxies in every direction. To a cosmologist, it all makes sense — a “flat” universe that’s the same every way we look at it.
Script by Damond Benningfield