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Possible Way to Measure Dark Energy?

  1. Aug 9, 2015 #1
    Hello everyone. I'm pretty new here, and I kinda joined this forum just to post this question. I have read many books on physics and cosmology, and although I have no scholastic training in it currently, I plan to study physics in college. Anyway, I get all sorts of ideas in my head, but this one I am about to share with you has been on my mind the longest. I would really appreciate anyone's input.

    Could you not measure dark energy and possibly harness it by putting a long cord with two large weights on either end and a generator with monitoring equipment in the middle? Dark energy would pull the space in between the weight apart, creating a force. The weights would carry the force, and the generator would harness the pulling force. The monitoring equipment would detect ripples and the strength of forces inside/on the cord, providing data that could be used to discern the nature of dark energy. This is certainly not very easy to do and requires a lot of resources, but it could be done.

    PS: I originally wrote this question as a comment on a Youtube video, but I realized its not the best place to ask these sorts of questions
     
  2. jcsd
  3. Aug 9, 2015 #2

    e.bar.goum

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    Hi Orthokid, welcome to PF!

    The trouble with dark energy is that, in the scheme of things, it's incredibly weak - we can only really notice it on cosmological scales (as an aside: the fact it's so weak, but nonzero is a pretty big issue in physics). For any noticeable effects on an apparatus like the one you described, dark energy would have to be much much much much much much stronger than what it is.
     
  4. Aug 9, 2015 #3
    Thanks, I learned something there.

    So the cord would have to be many light years long to measure any actual dark energy, or would gravitational interference just completely ruin any possible experiment of this kind? But I guess something similar is happening the laser-based gravity wave detector that is going to be launched, but that's its purpose.

    Edit: Sorry, I rant a lot
     
    Last edited: Aug 9, 2015
  5. Aug 9, 2015 #4

    e.bar.goum

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    Try many megaparsecs (millions of parsecs) -- we're talking much more than the distance between galaxies here, we're talking the distance between galaxy clusters -- and even then, the mechanical binding of the cord would probably kill it. You'd need to use laser interferometry, yes, but there exists no such laser or mirror that works on those kinds of scales! Even then, you wouldn't learn anything that supernova observations already tell us.
     
  6. Aug 10, 2015 #5

    Chronos

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    Yes gravity is vastly stronger over distances less than many millions of light years - which explains why we dont see galaxies flying apart.
     
  7. Aug 10, 2015 #6

    George Jones

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    And watch the interference pattern change with time. An alternative is to watch the redshift of galaxies change with time, which is called "redshift drift". Of course, this effect is extremely small, and has yet to be measured. Over the years, there has been a number of papers published on the theoretical aspects and experimental possibilities of this.

    Measuring redshift drift and using the results together with other date like supernova observations would be very exciting, and could, for example, be used as a test of the Copernican Principle that we are not in special position in the universe.
     
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