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B Is the formation of galaxy groups explained correctly here?

  1. May 31, 2016 #1

    PrincePhoenix

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    Gold Member

    Hello!

    I watched a video on the Youtube channel Kurzgesagt titled How far can we go? Limits of humanity
    The video attempts to explain why we may be limited to our local galaxy group even with science fiction technologies.

    During a part of the video (starting at 2:26), they try to explain how galaxy groups formed by saying that after the initial inflation period following big bang, gravity started to take hold. While it was too weak to get everything back together, in some pockets of space with more "denser" in terms of "energy" (quantum fluctuations before inflation) gravity was able to hold matter together and this formed groups/clusters of galaxies, within which matter is gravitationally linked. (If you think I might not phrasing it correctly and have time, I will appreciate it if you watch this section of the video directly)

    Is this explanation correct? Wouldn't a simpler explanation be that matter was unevenly distributed during inflation and only those areas with high densities came together to form galaxy groups?
    How do quantum fluctuations contribute to gravity? (My understanding of quantum fluctuations isn't much more than that explained in the video)

    Thanks in advance. :)
     
  2. jcsd
  3. May 31, 2016 #2

    Drakkith

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    The explanation is pretty much correct. As for "simpler", your explanation may be simpler, but it requires that someone already know a bit about how gravity works.

    Quantum fluctuations lead to slightly different densities in different regions of the very early universe. The regions that were more dense are the ones that collapsed to form galaxies. The regions that were less dense tended to become voids.
     
  4. May 31, 2016 #3

    PrincePhoenix

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    Thank you for the answer. :smile:

    Can you please explain how quantum fluctuations affected the distribution of matter? (I assume you were referring to the distribution of mass in space with your use of the phrase "...different densities in different regions...")
     
  5. May 31, 2016 #4

    Drakkith

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    The quantum fluctuations are variations in the position of matter and radiation in space via quantum effects (uncertainty principle, etc). This naturally leads to areas with higher or lower than average densities.
     
  6. Jun 1, 2016 #5

    1oldman2

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  7. Jun 1, 2016 #6

    PrincePhoenix

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    Thank you for the explanation.
     
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