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Space Science

Shape of the Universe Determined To Be Really, Really Flat 235

StartsWithABang writes: You might imagine all sorts of possibilities for how the Universe could have been shaped: positively curved like a higher-dimensional sphere, negatively curved like a higher-dimensional saddle, folded back on itself like a donut/torus, or spatially flat on the largest scales, like a giant Cartesian grid. Yet only one of these possibilities matches up with our observations, something we can probe simply by using our knowledge of how light travels in both flat and curved space, and measuring the CMB, the source of the most distant light in the Universe. The result? A Universe that's so incredibly flat, it's indistinguishable from perfection. Which means it's probably even flatter than Kansas.
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Shape of the Universe Determined To Be Really, Really Flat

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  • by MichaelSmith ( 789609 ) on Saturday May 09, 2015 @02:10AM (#49652165) Homepage Journal

    Not sure what OP is on about.

    • Re: (Score:3, Funny)

      by LogicLoop ( 1186965 )
      Not only is Kansas flat, it's literally flatter than a pancake [slashdot.org].
    • You're thinking of Missouri.

    • Re: (Score:3, Interesting)

      by Anonymous Coward

      I've driven clear across Kansas on US-50. The Western part of Kansas is ridiculously flat. In fact, that observation was the most memorable part of that portion of my trip. I kept wondering what geologic processes could produce such an even change in elevation. It's basically a huge geometric plane (also once a plain, obviously) at a few degrees slope, starting from just about the Colorado border and continuing for much of the state. The political border with Colorado, though it appears quite arbitrary on a

      • by AJWM ( 19027 )

        I kept wondering what geologic processes could produce such an even change in elevation.

        It (along with eastern Colorado and much of the other great plains states/provinces) is an old sea bed, the floor of the central inland waterway in the mid/late Cretaceous. Flat from millions of years of sediments, tilted slightly from being pushed up as the continent drifts westward. (Dramatically so at the Rockies). The foothills of the Colorado Rockies do not "end just short of the border" at least not anywhere

    • TFS refers to "flat" as being uniform in less dimensions - as seen on a 2D plan. Kansas is almost a perfect rectangle (while NE nibbled), seen from space. The Universe seem to be a rather uniform cylinder. I think.
  • Let us build dykes in the void outside the universe, and polder in some more vacuum !
  • If its surface is flat, what good a wormhole will do?

    • by tsa ( 15680 )

      That's what I thought too. And the conclusion of the article is 'We don't know the shape of the universe because we can't see far enough.' So the title of this is wrong too.

    • Haven't you ever seen the movies where they explain wormholes? They take a piece of paper, fold it and punch a hole through it. That's how a wormhole works. If the universe is flat, we just need to figure out 1) how to fold it, and 2) how to punch a hole, and we're good to go.
    • The universe appears flat at large scales. It isn't flat on small scales, as evidenced by gravitational lensing by massive objects. Wormholes probably don't exist, but if they do then they just affect the small scale structure of the universe, not the large scale.

  • by Anonymous Coward

    The universe is a communion wafer.

  • by Tablizer ( 95088 ) on Saturday May 09, 2015 @03:01AM (#49652297) Journal

    So, who are the lucky bastards who get the Dolly Parton universe?

    • So, who are the lucky bastards who get the Dolly Parton universe?

      Presumably, those are the alternative slasdotters that are married to the opposite sex and don't live in the basement either.

  • by jandersen ( 462034 ) on Saturday May 09, 2015 @03:01AM (#49652301)

    The assumption of GR is that space/time can be described as a smooth manifold - a manifold being intuitively something like a beach ball, donut or similar. Smooth means that when you look at a piece of the manifold at a sufficiently small scale, it looks more and more flat; it really is that simple, what makes it hard is when you introduce the technical tools you need to make precise calculations. So, since we don't actually know the size of the universe, perhaps what we can measure is that we are looking at a much smaller scale than we imagined.

    But, some will say, how about the speed of light? The age of the universe is known, so if it started out in the big bang as a single point, it can only be a limited number of lightyears across, right? There are several things to say, that might rock that particular boat a little. Firstly, we don't know that the universe was just a single point in size - in fact, the way QM is interpreted, it seems reasonable to think it wasn't. Secondly, if inflation happened, the universe went through a phase when it expanded a lot faster than the speed of light. And thirdly, of course, the speed of light is only known to be the limit within what we know as vacuum in the space-time we observe now, it only limits how much of the universe we can see now; we have every reason to assume that there is a lot more of it than that.

    • You seem to be the victim of a rather common confusion. Only within spacetime, nothing can travel faster than the speed of light. But there is no known law of nature prohibiting the expansion of spacetime itself at any imaginable speed. To such expansions of spacetime, the speed of light is meaningless. This is even the basic principle behind the Alcubierre Drive.
      • by dbIII ( 701233 )
        Fair enough, but going around "correcting" people with a concept that relies on negative mass looks like the sort of certainty that reduces with increased understanding of a topic.
        Also, if space isn't curved then where are we getting all that background heat from? There's a vast amount of it, 3K just about everywhere needs a bit of warming up, and if it's not being bounced back at us then where is it coming from?
    • The age of the universe is known, so if it started out in the big bang as a single point, it can only be a limited number of lightyears across, right?

      The Big Bang didn't happen at a single point.

      • by Livius ( 318358 )

        The Big Bang didn't happen at a single point.

        Well, actually we don't know that. That's an extrapolation based on math which breaks down if you get too close to the moment of the big bang. (If 'moment' is even the right word.)

        • The Big Bang didn't happen at a single point.

          Well, actually we don't know that. That's an extrapolation based on math which breaks down if you get too close to the moment of the big bang. (If 'moment' is even the right word.)

          No, we do know that, from the Cosmic Microwave Background. The early universe has been directly observed to be extremely homogeneous.

          • No, we do know that, from the Cosmic Microwave Background. The early universe has been directly observed to be extremely homogeneous.

            No, we really don't know that. The CMB is exactly the proof you're looking for. If all of its photons were emitted when space itself was very, very small, and space is now very, very big, it would indeed appear very homogeneous, and very very redshifted. The only real argument against it happening at a single point is that QED says that just doesn't work for them- but then again, they've always hated singularities, and I somewhat agree with them. But they're not arguing that it didn't happen at nearly a sin

        • We do know that. The CMBR demonstrates thatvery fact.

          The Big Bang was not an explosion. It had no epicenter. The entire universe; including space itself, expanded.

    • No cosmologist thinks the universe was just a single point in size. This is an error in how the big bang is explained to the public. Also, it is error-prone to try to compare the rate of expansion of the universe to the speed of light. These things are not comparable. The expansion of the universe is a scaling of the universe. For example, in one second, 1 meter becomes 2 meters. Then 1 parsec becomes 2 parsecs. You can't compare this to a speed. 1 meter going to 2 meters in one second is a lot slower than

  • by madsenj37 ( 612413 ) on Saturday May 09, 2015 @05:14AM (#49652525)
    The universe is all of space and time. We have not observed/measured/etc. most of the universe yet to determine its shape. The parts of the universe we have observed are flat. Until we observe more of the universe, we will not know if the universe is flat or not.
    • by Rich0 ( 548339 ) on Saturday May 09, 2015 @06:59AM (#49652683) Homepage

      The universe is all of space and time. We have not observed/measured/etc. most of the universe yet to determine its shape. The parts of the universe we have observed are flat. Until we observe more of the universe, we will not know if the universe is flat or not.

      Unless they say otherwise, if you hear physicists talking about the "Universe" they're probably talking about the observable universe.

    • We can see almost all the observable universe, from now until just a few hundred million years after the big bang. In other words, we can see most of the universe that there will ever be to see.

    • It's called inductive reasoning. And it's the basis of all science.

  • by Saysys ( 976276 ) on Saturday May 09, 2015 @05:30AM (#49652551)
    Here's an explanation: The universe is a hologram [youtube.com]
  • Since we apparently have a seriously large system that is flat what are the forces that would cause a flat universe to perpetuate itself? Rotation might offer an explanation but there is also the notion that some force pressing from the top and another force pressing from below might cause a flat universe. Let the speculation begin! If the universe is like a flat sea can the universe cascade over the edge?
  • You'd think based on what we know about smaller scale explosions that the universe would be spherical, but even explosions in a vacuum aren't perfectly spherical. The shape of the shrapnel field and gasses depends on exactly how the explosion occurs. Until we know how dark matter and dark energy affect regular matter and energy with respect to accelerating it there's no obvious way to determine what the shape of the universe would be 13+ billion years after its creation. Subtle imperfections in the initial,
    • What we know about explosions at any scale tells us nothing about the Big Bang, which was not an explosion.

  • ...that the flat universe is being supported by 4 elephants, and that these elephants in turn are standing on the back of a giant turtle, who is cruising the quantum realm between universes looking for quantum fish and insects to eat.
  • by fahrbot-bot ( 874524 ) on Saturday May 09, 2015 @12:32PM (#49653829)

    Which means it's probably even flatter than Kansas.

    The band or the state?

  • Seriously I don't get it, are they saying there are more dimensions?

    The article shows images of 2d things being wrapped around 3d things. So are they not saying by extension that our 3d universe is potentially wrapped in more dimensions, otherwise how could it be anything other than 3d.

    And a 2d universe can't bend because it is a f**king 2d universe otherwise it wouldn't be a ruddy 2d universe it'd be a 3d universe.

    This sh*t doesn't make any sense.

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