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Are the "cosmological constant" and the "universal constant" essentially the same?

  1. Jan 4, 2016 #1
    Are the cosmological constant and the universal constant essentially the same?
  2. jcsd
  3. Jan 4, 2016 #2


    Staff: Mentor

    I have never heard of "the universal constant". Do you have a reference for context?
  4. Jan 4, 2016 #3
    Thank you for replying, DaleSpam. I seem to see "universal constant" used interchangeably with "cosmological constant." That's why I wonder if they're the same thing. The best I can figure out, is that a "universal constant" is any constant in the universe (such as the invariance of the speed of light), and that Einstein's "cosmological constant" is simply one of these universal constants. But I'm not sure if the two are actually the same thing, or if the Einstein's cosmological constant is simply one of many different "universal constants." :)
  5. Jan 4, 2016 #4


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    It's difficult to tell what an author means by a term without seeing the context. Can you provide a quote or a link where you have seen "universal constant" used?
  6. Jan 4, 2016 #5


    Staff: Mentor

    Wikipedia lists c (speed of light), G (gravitational constant; not to be confused with cosmological constant) and h, ħ resp. (Planck constant) as universal constants; others as constants of their related fields. However, the cosmological constant, hubble factor resp., aren't listed at all.
  7. Jan 4, 2016 #6
    Fresh_42, I think your answer helped me figure things out. I think the answer to my question is that Einstein's Cosmological Constant is not a "universal constant" (like the speed of light) because the Cosmological Constant was proven untrue when the universe was shown to be expanding. Thank you, everybody, for your help! :)

    Best regards,
  8. Jan 4, 2016 #7


    Staff: Mentor

    You can find further interesting aspects and discussions on the cosmological constant searching PF here.
  9. Jan 4, 2016 #8

    George Jones

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    The cosmological constant might be a universal constant, like G or c, but it also also might be derivable from quantum field theory or some theory of quantum gravity; we just don't know what the answer to "Is the cosmological constant a universal constant?" is right now.
  10. Jan 4, 2016 #9


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    Staff: Mentor

    I'm not sure what you mean buy this, but if it is a reference to Einstein's static universe model, the fact that that model was disproved by the discovery of the expansion of the universe does not mean "the cosmological constant was proven untrue". Our current model of the universe also has a nonzero cosmological constant; it just also has expansion.
  11. Jan 4, 2016 #10


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    The cosmological constant is used to explain the acceleration of the expansion, due to dark energy. What it all means is still an open question.
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