🚀 go-pugleaf

Dale Bass writes:

>        c) the long-time stability of the solar system
>    that several of us discussed earlier.  Biology tends to tell us
>    that the solar system (or at least the earth's orbit) has been stable
>    for long lengths of time.  Calculations and perturbation theory tend
>    to tell us differently.

I'm baffled.  The calculations refered to suggest that certain orbital parameters
of some planets (maybe all) vary in a chaotic manner.  However, the amplitude
of the variations is very small and I know of know reason to suspect that
they would get large over billions of years.  Instead, we seem to be seeing
(possibly) chaotic behavior within a small part of phase space.  In other words,
biology, geology and celestial mechanics seem to be in accord.  Am I missing
something?

>         e) why does the Hubble 'constant' float all over the place.  It
>    almost seems like one could select a value at random and find very
>    good support for that value in astrophysical observations.

You've lost me here too.  Hubble's constant gets quoted at values from
as low as 40 km/sec/Mpc to 100 km/sec/Mpc.  Most determinations come in
from 75 to 90.  This is random?  I think anyone who knows how these
distance determinations are arrived at considers this a remarkable
concordance.
-- 
"Quis tamen tale studium, quo ad primam omnium rerum causam evehimur,
tamquam inutile aut contemnendum detractare ac deprimere ausit?"-Bridel
Ethan T. Vishniac, Dept. of Astronomy, The University of Texas at Austin
Austin, Texas, 78712                   ethan@astro.as.utexas.edu