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Difficult question Dark energy

  1. Mar 20, 2014 #1
    I have written sci-fi short story. Question is how fast and loose am I playing with science and theories about the big bang and dark energy. This is the summary of assertions in the story.

    1) Dark energy is the reason for the original expansion of the observable universe including (space and time).

    2) Dark energy was in balance with other forces at the moment of the big bang.

    3) Dark energy is like a candle lit at both ends - meaning it will deplete at some point because its rate of consumption/use is increasing. (universe expanding at an increasing rate)

    4) My fiction just assumes (3) and posits that at some point in the future the observable universe begins to collapse like a deflating bubble.

    5) Assuming 3 and 4 (this is the really large leap). As the universe collapses, space, time and matter are erased at (for lake of a better word) the event horizon of the collapse.

    6) An implied assumption is that the process may resemble inflation theory in reverse. (also implied would be that the rate of collapse would be increasing).

    7) The last assumption is also large. The remaining inhabitants are aware of the process, have migrated to the center of the universe, where they find a central super-massive black hole.

    The fiction is a humorous treatment, which stands on its own from that point of view, but I'd like some help if possible to shave a little of the hair off the big assumptions. The task exceeds me.
  2. jcsd
  3. Mar 20, 2014 #2


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    Wrong. Dark energy was irrelevant there - it is noticable only with very large distances, as we have them today.
    See above.
    Wrong. The more expanded the universe is (and therefore the more matter is spread out), the more dominant dark energy becomes.

    You can assume contraction in some distant future, but then you need something completely new - or directly an alternative universe.
    What does that mean?
    I doubt that, but with a suitable alternative universe...
    There is no center of the universe. As an analogy: where is the center of the surface (!) of earth?
  4. Mar 20, 2014 #3


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    As mfb has pointed out you have the science completely wrong, so you should just focus on the story and just use hand-waving on the physics. Most readers aren't likely to care that much about the science facts if the story is gripping.

    You might try the link in my signature to help dispel some of your misconceptions.
  5. Mar 20, 2014 #4
    Thanks for your reply its very helpful. As for number 7, if the universe were shrinking you'd reach a point where you could estimate the center. i.e., The entire universe becomes observable. I think I understand, however, that even if you could observe the entire universe the apparent center would be unlikely to have anything to do with a 'center' or starting point. No space or time = no coordinates.

    Thanks again, I think I will make additional effort to wrap my mind around this.
  6. Mar 20, 2014 #5


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    No, that is not correct (about the center at least). If the universe has no center now, it had no center then. No one knows what the topology of the universe is but it does not, never has, and never will, have a center.

    It might be infinite, in which case it was infinite then (weird concept but taken one that is taken very seriously) or it might be finite but have a topology that has no center
  7. Mar 20, 2014 #6
    I will follow the link. I don't think I'll be able to paint over the science and theory, because its too central to the story. I'll have to come up with a minimally plausible set events that fit an alternate universe. Even given my lack of knowledge, I could see weakness in the sci part of the fi.

  8. Mar 20, 2014 #7
    I realize I'm quoting your post a second time, but thanks for the link. I'm amazed at how much clearer the whole subject is.

    Check me to see if I've got this right.

    1) the expansion of the universe (at the galactic level) is a non-local relativistic observation from a single point (here).

    2) the universe is better described as a two dimensional surface like the surface of a black hole, but shape should not be inferred because the curvature of a black hole is a local space time observation denoting the localized curvature of space by gravity.

    3) if I have 1 and 2 right then the universe is not bound together (post 5 billion years) gravitationally... or gravitation effect has become non-significant due to distance created during early expansion. No bounce (just a rocket having achieved escape velocity).

    So if my fiction postulated a dramatic increase in the rate of expansion of the universe. One could then envision the remnants of a dying Milky-way becoming the observable universe which has a super massive central black hole. And that black hole would conveniently behave in local space time relativistic way.

    Assuming I haven't gone too far astray all I'd need would be a 'mechanism' that would cause both the normal matter and dark matter to collapse in a non-local way. Single 2d point = BB.

    Or, all matter in observable remnant collapsing producing a non-local event.
    Last edited: Mar 20, 2014
  9. Mar 20, 2014 #8


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    Within galaxies, there is no expansion. Expansion happens only at larger scales. And the observation point does not matter, every point sees the same expansion in every direction.

    No. The balloon analogy is just an analogy - compared to our universe it has one dimension less to make it easier to imagine.
    In principle, it can be measured, but our current measurements are not sensitive enough to do so.
    It is still a relevant factor for the expansion of the universe.
    You don't even need a dramatic increase, just a lot of time. The local group (including Andromeda and a few smaller galaxies) will stay together*, everything else will get more and more distant and unreachable.
    I'm not sure what you mean with "local space time relativistic way".
    What does that even mean?

    *excluding more exotic scenarios like a big rip.
  10. Mar 21, 2014 #9
  11. Mar 21, 2014 #10
    Thanks for the link. And, yes and no about the hard/soft. Some fantasy fictions appear to be science fiction on the surface, but they were never meant to be hard sci-fi. The problem is, if your story has the appearance of being solid/hard sci-fi you can't just ignore the junk. You have to do what any person does when writing a serious paper (explore the weakness', ask questions and hope you can make it minimally plausible). If you don't, you're open to a lot of criticism even though your work is not really sci-fi based.

    There are a lot of people who consider Ender's Game (and the books that follow) to be science fiction, but they're not. They're fantasy mixed with science fiction and 'Doctor Who' is something in a category by itself.

    My fiction is caught in a catch 22, the plot requires an approaching end to the universe and a galactic civilization trying to create a new universe out of what's left of the observable universe (I won't even go into the complications involved in the sub-plot). Another words the impossible, so I'm left gleaning through cosmology in order to make the work palatable in that respect.

    It's a good work so I feel obligated to try and save it, otherwise I have to file it under 'g'.
  12. Mar 21, 2014 #11
    The universe is still expected to have an end; it'll just be in the other direction. Expansion will continue, until the Milky Andromeda is the only galaxy in the visible universe. Entropy will continue, until all that's left are cold, dead stars. The once-great civilizations which remain will be reduced to mining ancient cinders for their matter, and fusing or annihilating it to temporarily stave off the cold black. Eventually, they'll run out of resources, and life will end.
  13. Mar 21, 2014 #12
    I've already restructured the story to have an end of the observable universe (on the galactic scale, via expansion), but I seem to be unable (at this time) to envision a galactic civilization creating a new universe out of what remains. All attempts, so far, have been timey whimey.

    The sub-plot involves embedding a message to future inhabitants of the new universe in the background radiation BB, but implies a high order of similarity to the previous universe (minor variations, all of which have no causal effect on the evolution of the new universe). The sub-plot may have to go if I can't make the timey whimey into something timely curious, or something else entirely.
  14. Mar 21, 2014 #13


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    You are going where science just doesn't go. " a galactic civilization creating a new universe" is pure la la land which is why you're having trouble making it work.
  15. Mar 21, 2014 #14
    Yup. Timey Whimey, here I come...
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