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Universe's Curvature Measured?

Posted by Hemos on from the it's-four dept.

jmobiusmaximus writes "Right next to the wormhole site on the BBC News page is an article about the results of the Boomerang project in Antarctica. This resulted in a new map of the 2.7K cosmic microwave background radiation, which is thought to be a remnant of the energy released in the Big Bang. The BBC News synopsis isn't bad, and has some links that will answer most "WTF?" questions. For those of you who have taken a little bit of physics, the original Nature article is better. This could have a large impact on our understanding of the universe's evolution and will probably be the source of much debate in the near future. "

3 of 161 comments (clear)

  1. Flat, Currved, huh? by rangek · · Score: 5

    The problem here is that they are talking about the curvature of four dimensional space time. One way for us to visualize this is to pare things down to a two dimensional sheet. Imagine teh universe is a plastic sheet lying on the floor. The sheet can be flat, having zero curvature (because the second derivative of the sheet "height" is zero), or it can be curved. If it has negative curvature everywhere, it could be something like a sphere. A saddle on the other hand has positive curvature. That is, the second derivative is positive somewhere.

    All of this seems kinda wacky when applied to four dimensions. We can't visualize four dimensions easily, let alone what thier geometry looks like. And that is really the point here. On a flat surface (universe), normal Euclidean geometry holds. E.g., two parallel line never intersect, the sum of the interior angles of a triangle is 180, etc. On a curved surface (universe), this is not true. Draw a triangle on a deflated ballon (the flat universe) and then blow it up. The sum of the interior angles increases.

    Pretty neat, huh? And that is some of the reasons they are looking into this.

  2. FAQs by Anonymous Coward · · Score: 5

    I'd advise Slashdot readers to look at the Cosmology and Relativity FAQs, since they probably answer a lot of questions people are tempted to ask.

  3. What the experiment is about by Alexey+Goldin · · Score: 5

    Let me chime in as a member of competing team (http://topweb.gsfc.nasa.gov) that did not make it on time to get all the credit.

    This is the great result, comparable only to discovery of microwave background radiation in 1965 and first detection of CMBR anisotropy by COBE in 1992. It tells us much more then flatness of the Universe. From the results of this and followup experiments (ours will be somewhat more precise when we finally do it) it will be possible to find how much of the matter in the universe is barionic (composed of protons, neutrons and electrons) as opposed to stuff we have no idea about, which is probably contains up to 90-95% of the mass of the Universe. It will be possible to measure often mentioned energy of vacuum (do not count on using it --- not only it is low, it is also unextractable). Boomerang already a strong evidence in favor of inflation --- a strange theory, describing how most of matter in the universe was created from nothing, just because its positive rest energy was compensated by negative gravitational energy, so that total energy of the flat universe was and remains zero (this is how you create the whole Universe from nothing without violating the law of energy conservation). Future experiments will tell us more about how inflation happened and what kinds of fields and particles are responcible for it. We definetly will learn new things about fields and particles at energies far above what can be achieved in accelerators.

    We live in interesting times.

    BTW, read http://www.astro.ucla.edu/~wright/cosmolog.htm --- it is a good introduction to cosmology.