Early Dark Energy and Cosmic Tension

To avoid talking any more about you-know-what I thought I would continue the ongoing Hubble constant theme. Rhere is an interesting new paper on the arXiv (by Hill et al.) about the extent to which a modified form of dark energy might relieve the current apparent tension.

The abstract is:


You can click on this to make it bigger; you can also download the PDF here.

I think the conclusion is clear and it may or may not be related to a previous post of mine here about the implications of Etherington’s theorem.

Here’s my ongoing poll on the Hubble constant poll. Feel free to while away a few seconds of your time working from home casting a vote!



5 Responses to “Early Dark Energy and Cosmic Tension”

  1. Phillip Helbig Says:

    EDE is a rather ad-hoc proposal, not far from angels pushing things about to explain what we observe. Fortunately, the data seem to reject it.

    My bet is that the “tension” is caused by some trivial error. Sarkar has uncovered some of this. (This might also reduce the significance of evidence for the cosmological constant from supernovae, but this doesn’t imply that there is no cosmological constant, since otherwise many other tests would have to be wrong.)

  2. Jim Dunlop Says:

    How is this still even a thing? Some people should read about the history of the Hubble Constant and be delighted the agreement is now so good. This sort of nonsense really gives astronomy a bad name.

    • telescoper Says:

      Things will be things for as long as there are still things.

    • I see Jim’s point. I’ve told it before, but it is worth repeating. In gravitational lenses, a long time delay corresponds to a low Hubble constant and vice versa. There was a debate about the time delay in 0957+561 (the first gravitational-lens system), with Bill Press pushing for a long delay and others (from Hamburg with Jaan Pelt from Estonia but also Rudy Schild) pushing for a short one. This debate mirrored the one between Sandage and de Vaucouleurs over the value of the Hubble constant from more-traditional methods, which was still raging at the time. At the gravitational-lens conference in Liège in 1993, during a talk on the various time delays, Paul Schechter cried out from the audience “Where’s the problem? They agree at three sigma!”

      By the time of the next big gravitational-lens conference, in Melbourne in 1995, the pendululm had swung to the short delay. Press and Schechter (who of course had collaborated on another topic long ago) were both there. I remember Press introducing himself in his talk as the front end of the Press–Schechter horse. I couldn’t see Paul’s face (or anything else) at the time, as he was sitting far behind me.

      Press did make an interesting statement: “Someone knows the Hubble constant to two decimal places; we just don’t know who that person is.”

      And how can that be almost a quarter of a century ago? 😐

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