In article ,
"Phillip Helbig (undress to reply)" writes:
The real question is whether there is any real tension between Planck
and "local" measurements.

I agree that the most likely reason is some small systematic error.

it probably makes sense to wait and see if the tension is real
before trying to come up with something which would make the Hubble
constant depend SLIGHTLY on the redshift range in which it is
measured.

While I also agree that coming up with possible explanations isn't
worth a major effort, I think a bit of speculation might not be a bad
idea. It might suggest independent avenues of research to see
whether there might be evidence for some hypothesis or other.

I'm not enough of an expert to have any real idea what might cause
discrepancies between the local and CMB values of the Hubble
constant. I am _guessing_ a "hiccup" in the expansion history might
do it, but I have no idea what might cause such a hiccup nor how one
might test that. Any other ideas?

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