Re: Moorad's assumed timeline

From: George Murphy <>
Date: Thu May 20 2004 - 14:09:20 EDT

----- Original Message -----
From: "Alexanian, Moorad" <>
To: "Michael Roberts" <>; <>
Sent: Thursday, May 20, 2004 11:17 AM
Subject: RE: Moorad's assumed timeline

> The best example to illustrate what I am saying is forensic science. Here
one collects data that are studied by means of experimental sciences and
used as evidence provided to the district attorney for possible prosecution.
The district attorney forms a historical timeline wherein he fits in the
evidence he has. It is on the basis of that timeline that the prosecutor
seeks to indict a person by presenting the case in court.
> In cosmology, the timeline is provided by mathematical models based on the
Hilbert-Einstein equations of general relativity and solved assuming
symmetries by the Russian meteorologist and mathematician Aleksandr
Friedmann. In historical geology, evolutionary theory, etc. there are no
mathematical models and so the workers in those fields fit the data also in
an assumed timeline.

    Not exactly. A timeline can be established with much simpler models -
i.e., ones using Newtonian gravity or even neglecting gravity entirely. If
one puts Hubble's relation v = Hd in the form v = d/t then t = 1/H ~ 14 x
10^9 yr. The Einstein equations are needed for a more detailed model but
not for establishing the order of magnitude of what one may cautiously call
"the characteristic time of the universe."

    By bringing in the Einstein equations you exaggerate the difference
between the sophistication of what's needed in cosmology & in historical
geology. Furthermore, there are mathematical models which deal with a
crucial aspect of the age of the earth, radioactivity & the relative
abundances of various isotopes.
& even furthermore, those models are not completely disjoint from our
cosmological models because determination of ages from isotope abundances,
at least for things like U235/U238, depend on understanding the formation of
nuclei in supernovae and other cosmological data.

    Furthermore, while the simplest procedure is to assume spatial symmetry
& isotropy of the universe, as Friedmann did, there are plenty of
cosmological models - both exact solutions of the Einstein equations and
approximate ones which are perturbed versions of the Friedmann models -
which don't have all those symmetries.

    Moorad, I can argue as strongly as anyone that physics is "harder" than
other sciences. But this doesn't mean that those other sciences aren't
sciences at all or that they can't tell us anything about the past. You
have tried to make such a case several times in the past but it just won't
work. As a physicist I appeal to you to give it up.

Received on Thu May 20 14:10:00 2004

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