3 ms·

Thanks! So the currently accepted model says the acceleration will grow indefinitely but our observations are saying that the acceleration levels out to a non-z

• mr_mitm 3y ago
  No, I think the confusion here is the difference between "acceleration" and "expansion rate". It's less ambigious when using math: https://en.wikipedia.org/wiki/Lambda-CDM_model#Cosmic_expansion_history https://en.wikipedia.org/wiki/Lambda-CDM_model#Cosmic_expans... a is the scale factor, which goes as sinh^(2/3). a' and a'' will always increase, but the _expansion rate_ a'/a will approach a constant value from above. Besides the Hubble tension discussed in the article, there is no real discrepancy between observations and theory.
  • bmitc 3y ago
    > a is the scale factor, which goes as sinh^(2/3). a' and a'' will always increase, but the _expansion rate_ a'/a will approach a constant value from above. Thanks for that. I didn't realize there was such a definition of expansion rate and was going off the intuitive meaning of the terms. Thank you for the clarifications.