Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

B Can Cosmological Constant contract (negative)?

  1. Aug 30, 2016 #1

    Can the cosmological constant become so rigid as to resist the 120 magnitude quantum contribution? Where is the mathematical terms for it in GR EFEs? is the effect like contraction instead of expansion? Because the 120 magnitude quantum contribution should immediately warp spacetime after Big Bang.. but it is somehow cancelled.. maybe the cosmological constant can contract or negative value equal to 120 magnitude too?
  2. jcsd
  3. Aug 31, 2016 #2
    Hi cube137,

    As I understand it the problem of 120 oom is not within GR to explain but it is a problem in QFT.
    QFT vacuum energy is much higher than the measured cosmological one.
  4. Aug 31, 2016 #3


    User Avatar
    Science Advisor
    Gold Member
    2017 Award

    Yes, and it's really the most enigmatic problem of contemporary physics. The isssue is still more or less in the same status as is written in Weinberg's famous review on it:

    The cosmological constant problem. Steven Weinberg. Rev. Mod. Phys. 61, 1 – Published 1 January 1989.
    http://dx.doi.org/10.1103/RevModPhys.61.1 [Broken]
    http://www.itp.kit.edu/~schreck/general_relativity_seminar/The_cosmological_constant_problem.pdf [Broken]
    Last edited by a moderator: May 8, 2017
  5. Aug 31, 2016 #4
    I read them.. but something I still can't understand. In the Anthropic argument.. how come they just stated the cosmological constant is small in our universe.. why didn't they consider the 120 magnitude quantum contributions.. what is the exactly formula of the cosmological constant.. where is the variable that is negative or the one where you plug the negative 120 magnitude (to the quantum contributions) and still making the cosmological constant small?
    Last edited by a moderator: May 8, 2017
  6. Aug 31, 2016 #5


    User Avatar
    Science Advisor

    You are misunderstanding.

    We go out and measure the cosmological constant by looking at the redshift of supernovae and applying the equations of general relativity. The result is that the cosmological constant is very, very small.

    Then we go and look at quantum theory and calculate the energy of the vacuum, which we think ought to be the same as the cosmological constant. The answer is very, very big - 120 orders of magnitude bigger than the GR-based measurements.

    There is no way to make the large value into the small one. These two results just contradict each other. There is something we don't understand going on here. Hopefully quantum gravity will explain it all - but we don't have that theory yet.
  7. Aug 31, 2016 #6
    But that's the point. In the Anthropic multiverse arguments.. there are billions of universes with different values of the constants.. we just happened to be in a universe with small constant.. but still it doesn't take into account the 120 magnitude quantum contributions.. so what is the point of the Anthropic argument.. it is supposed to solve what happened to the 120 magnitude quantum contributions and why is the cosmological constant small in spite of it.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted

Similar Discussions: Can Cosmological Constant contract (negative)?
  1. Cosmological Constant (Replies: 4)

  2. Cosmological constant (Replies: 7)

  3. Cosmological constant (Replies: 1)

  4. Cosmological constant (Replies: 4)