Re: Scientific Definitions

Kent <musquodster@xxxxxxxxx> wrote:

Wendel Fendel wrote:

By and large falsification is a valid methodology. That is how we know
Newton's Law of Gravitation is false. It mispredicts the motion of Mercury.

Assuming you know the shape of the sun sufficiently well that you can
rule that out as a possible cause. In the sixties or seventies there
was a flurry of activity claiming that the precession was due to the
shape of the sun. I as not sure if the shape of the sun was measured
more accurately or the proponents were ignored and retired. Never
underesitmate the ability of people to come up with alternate
explanations.

Perhaps a nitpick...

There was never, to my knowledge, a suggestion that the oblateness of
the Sun could explain the entire precession of Mercury's perihelion.
In the mid-1960s, a couple of (very difficult) visual measurements
suggested that the Sun's shape was nonspherical enough to account for
about 10% of the precession normally explained by general relativity.
This would have required a modification of general relativity, though
Newtonian gravity would have still been strongly excluded. In particular,
an alternative theory---Brans-Dicke theory---which added an extra scalar
field to general relativity would have become a good candidate.

Later, more accurate, measurements, including those taken by satellites
orbiting the Sun, showed that the 1960s measurements of the Sun's shape
were wrong. These have been further confirmed by helioseismology. The
controversy is now pretty much settled, in favor of general relativity.

(There's some hope that a future Mercury orbiter, which would allow a
much more precise measurement of Mercury's perihelion advance, would
give results accurate enough to tease out the tiny effect of the Sun's
oblateness.)

Steve Carlip

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