Mercury and General Relativity Re: All answers to C S Lewis

I promised a further entry on the Corliss book _Moon and Planets_ to see
what it was he said about the perihelion advance of Mercury's orbit that
might bring Einstein's General Relativity Theory into doubt. "Al" raised
the issue, claiming that this proved that scientists were concealing the
truth and supressing dissent, etc. The book was published in 1985.

In fact the main problem is that Corliss's book is completely out of date
with regard to quality of data and proposed explanations for all sorts of
things related to Mercury.

Elsewhere we have seen that modern observations, of both the oblateness of
the Sun and of solar oscillations that tell us about internal structure, now
provide a small J2 quadrupole moment of the Sun, small enough that previous
doubts about the influence of solar oblateness on perihelion advance are
shown to be errors of observation. The perihelion advance is compatible
with GR to several decimal places in the 43 arcsec/century excess in the
advance. Not only that, but a study of radar determinations of planetary
orbits showed that the perihelion advances of Venus and Mars were compatible
with GR as well.

All the references were given in the "C. S. Lewis" thread (by another
poster) and the interested reader will have to google for them, as I'm not
going to repeat all the lists again.

To be fair to Corliss, he recognised the facts and evaluated them fairly,
except for one problem. To quote:

"The modern value of 574.1 arssconds per century for the advance of
Mercury's perihelion is considered very accurate. The measurements of solar
oblateness, however, are still highly controversial. Since these are
crucial in determining whether a real anomaly exists here, the overall
rating for the data is low. Rating: 3."
....
"**If solar oblateness is large enough** [my emphasis] to change the
residual so that the predictions of the General Theory of Relativity are far
off the mark, one of the major supporting pillars of General Relativity will
be shattered. Rating: 1."

The difficulty is that Al read this and thought there was a serious problem
with GR, when of course after another 20 years of observing the serious
problem turned out to be with the data. In fact Corliss was saying that
there would be a serious problem ONLY if the solar oblateness data were
correct (and he was correct on this point). But the way he expressed this
was misleading to people like Al. It now turns out that the data, as of
1983, were off by orders of magnitude. I point out of course that the
measurements are extremely difficult and required a lot of technical
development.

Corliss also discussed three other anomalies, the eccentricity and high
inclination of Mercury's orbit, and its capture in a 2:3 spin:orbit
resonance rather than 1:1. In fact, further work by dynamicists has since
shown that the orbit evolves over time and that in the past Mercury's
eccentricity might well have been smaller, and the inclination smaller, and
that the type of resonant capture depends on the way in which the
eccentricity changes. In other words, these otherwise mysterious anomalies
have also been resolved and are no longer mysterious.

--
Mike Dworetsky

(Remove "pants" spamblock to send e-mail)

.

Relevant Pages

  • Re: This is What Einstein Actually Did.
    ... | other planets about their orbits in a weighted distribution depending ... | on the time that each planet spends in each portion of the orbit. ... the deviation between the measured perihelion ... | Had Einstein lived one century earlier and had sufficient data been ...
    (sci.physics.relativity)
  • Re: Light speed invariance
    ... some fundamentals taught to budding astrophysicists such as yourself. ... from a theoretical prediction. ... As to your "longitude of perihelion" you first need to understand how ... ascending mode as the point where the body in orbit rises north of the ...
    (sci.physics.relativity)
  • Re: YASID
    ... and the colonists find it hot>>> at perihelion, cold at aphelion, but ... an orbit that ranges from>> Venus-distance to the sun to ... Mars-distance would kill life on planet>> Beta well before Beta reached either ... especially at>> the Venus end. ...
    (rec.arts.sf.written)
  • Re: Discovery of PLuto ...
    ... > Best I can do with limited time and what I have at home. ... Long integrations of Pluto's orbit show it ... >> perihelion points coming closer now, or they are going to be more separated ... The orbit of PLuto is chaotic; it was confirmed with the simulation of the Solar System ...
    (sci.astro)