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The Big Bang's Last Great Prediction

Posted by samzenpus on from the in-the-beginning dept.

StartsWithABang (3485481) writes "Even with the add-ons of dark matter, dark energy and inflation, the Big Bang still thrives as the most successful scientific model of the Universe ever constructed. It not only accounting for phenomena like the abundance of the light elements, the cosmic microwave background, and the Universe's large-scale structure, but it's led to observable predictions about their details that have since been verified. But there's one thing the Big Bang has generically predicted that we haven't been able to test: a cosmic background of low-energy, relic neutrinos."

7 of 80 comments (clear)

  1. Theory as it stands is wrong by nemasu · · Score: 5, Interesting

    I just found this out a couple weeks ago, and it blew my mind, the big bang theory actually does not explain things we can actually observe right now.
    For instance, the Hercules–Corona Borealis Great Wall

    --
    I made an app! Shoutium
    1. Re:Theory as it stands is wrong by nemasu · · Score: 3, Interesting

      Ah, so what you're saying is that the current theory is not disproved, but the current model of the theory.
      Well don't I feel silly now.

      --
      I made an app! Shoutium
    2. Re:Theory as it stands is wrong by Charliemopps · · Score: 4, Interesting

      To explain further... metric expansion is the central premise of the big bang theory. SPACE is growing larger... the matter within it is not moving away from each other. (well they might be but that's not relevant) So if you and I were standing next to each other and not moving, the distance between us would still be growing. On small scales the effect isn't even measurable it's so small. But the effect increases with the more distance between us. When you get to galactic scales the effect is enormous. The speed of light limit is a result of the geometry of space-time. Think of it like a right triangle... you change one line, and that affects the angles and lengths of the others. Expansion is like changing the size and shape of the paper the triangle is drawn on.

      Or at least that's always been my understanding. Physicists feel free to correct me. Time Cube guys, stay out of it. :-)

  2. Neutrino temperature by Framboise · · Score: 5, Interesting

    The orginal article keeps quoting the temperature of 1.96K as the neutrino background temperature, as found in most textbooks on the topic. This is a relic of the time people were assuming massless neutrinos. The confusion is maintained by people using the temperature as a synonym of energy. Actually the non-zero rest mass energy must be subtracted, providing the real kinetic energy of these particles (moving now at 100-1000 km/s) that would be exchanged with a super large thermometer (in view of the tiny interaction cross section). The effective neutrino temperature would then be measured in the milliKelvin range.

     

  3. Re:Bothered by Sockatume · · Score: 4, Interesting

    That's a legitimate question, and in fact cosmologists are curious about the idea of whether the big bang is a unique event or something that can happen spontaneously. The hope is that advanced physics will provide some answers.

    As for the "locality" issue: cosmologists address issues related to the entire observable universe. Speculations on regions that are unobservable aren't really a topic for scientific investigation, except where a good model implies certain (untestable) things about unobservable areas.

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    No kidding!!! What do you say at this point?
  4. Not quite by mbone · · Score: 5, Interesting

    ...the only interaction they can conceivably have with normal matter is via a nuclear recoil.

    No, not quite. These neutrinos also interact gravitationally with ordinary matter, which, of course, the author knows, but just doesn't think of. That introduces two possible means of detecting them, either gravitationally, or by using the Sun or other bodies to focus them on a detector, thereby greatly amplifying their signal.

  5. Re:Bothered by mbone · · Score: 3, Interesting

    In "eternal inflation," inflation is seen as something like the natural state of the universe, with little nodes from time to time budding off of the inflationary stream, and forming universes like our own, with inflation continuing elsewhere (from our standpoint, very very far away, much beyond any distance we could reach, even if we traveled at the speed of light). In such theories, the big bang is not the time of the birth of the universe, it is the time of the cession of inflation here, in our part of this bigger universe. This is one type of what Max Tegmark calls a Level I Multiverse (as there would be other "big bangs" elsewhere).

    It may be that the recent detection of cosmic acceleration (aka "dark energy") indicates that our universe may (if the acceleration itself starts to accelerate into something like a "big rip") return to this natural state of inflation in due course, and that might be the typical fate of "normal" universes like ours.