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Old November 12th 19, 09:39 PM posted to sci.astro.research
Phillip Helbig (undress to reply)[_2_]
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Posts: 273
Default Is the Universe Younger than We Thought?

In article , Steve Willner
writes:

To the question in another message, I don't see why some local
perturbation -- presumably abnormally low matter density around our
location -- wouldn't solve the problem in principle, but if this were
a viable explanation, I expect the speaker would have mentioned it.
It's not as though no one has thought about the problem. The
difficulty is probably the magnitude of the effect. I don't work in
this area, though, so my opinion is not worth much.


I'm sure that someone must have looked at it, but is the measured Hubble
constant the same in all directions on the sky? (I remember Sandage
saying that even Hubble had found that it was, but I mean today, with
much better data, where small effects are noticeable.) If it is, then
such a density variation could be an explanation (assuming that it would
otherwise work) only if we "just happened" to be sitting at the centre
of such a local bubble.

Of course, some of us remember when the debate was not between 67 and
72, but between 50 and 100, with occasional suggestions of 42 (really)
or even 30. And both the "high camp" and "low camp" claimed
uncertainties of about 10 per cent. That wasn't a debate over whether
one used "local" or "large-scale" methods to measure it, but rather the
deference depended on who was doing the measuring. Nevertheless, it is
conceivable that there is some unknown systematic uncertainty* in one of
the measurements.

---
* For some, "unknown systematic uncertainty" is a tautology. Others,
however, include systematic uncertainties as part of the uncertainty
budget. (Some people use "error" instead of "uncertainty". The latter
is, I think, more correct, though in this case perhaps some unknown
ERROR is the culprit.