From: throopw@sheol.UUCP (Wayne Throop)
Newsgroups: talk.origins
Subject: Holden is correct about "tug of war"
Date: 05 Nov 92 01:29:06 GMT

No, this isn't a Holden parody.  He really *is* correct on this point.
(He may or may not realize *why* he is correct, but nevertheless, he is.)

: From: csfed@uxa.ecn.bgu.edu (Frank Doss)
: Message-ID: <BwxzpF.Crz@uxa.ecn.bgu.edu>
:: From: news@fedfil.UUCP (news) (Ted Holden)
:: Message-ID: <94@fedfil.UUCP> 
::: In this tug of war, the creatures who were under the influence of the
::: reduced felt effect of gravity would have been, in effect, the ROPE in
::: this tug-of-war.  I wonder how well I would feel if I had ~1 G pulling
::: on my head while 1 G was pulling on my feet.
:: Whales are the "rope" today, caught between gravity and water bouyancy.
:: They do not suffer from it.
: Bouyant objects are lighter than whatever it is they are bouyant in.  If
: you were to tether this object to the bottom of the seas, the tether
: would be the rope.

Oh, foo.  Apples, oranges and bicycles are being mixed here.
Let me try to sort it out.

To start, Ted includes support by fluids (such as water) in possible
causes for his "felt effect".  Whales are indeed in a "tug of war", but
the "tug" is applied so evenly to their body surface that it is not
(for the most part) a problem.  They could not stand *arbitrarily*
large g loads simply by floating in water: eventually blood pressure
would exceed tissue strength, lungs would collapse, and so on.

But Ted agrees that we must rule out water support for sauropods, for
various adequate reasons.  And Ted's scenario for felt-effect-reduction
for the sauropods isn't analogous to buoyancy for whales.  Ted's
scenario is that the gravitation of some other planet "cancelled" part
of earth's gravity.  For that scenario, there's not only no rope,
there's no tug-of-war problem whatsoever.  The force isn't applied to
the surface at all, but to the whole body volume.

Remember, the earth's gravity works on the whole body, head and feet
alike.  It isn't like a "heavy boots" effect that "pulls on" the body
part closest to the earth.  It is exactly the same with the gravity of
another body "overhead".  It too would act on head and feet alike.  The
only way an inertial force (such as gravity, or the centrifugal and
corriolis pseudoforces) can affect the head and feet differently, is
via the equivalent of tides.  To be a problem for humans, the tides
would have to be on the order of a g per meter or so, which for a
gravitational source would imply a neutron star or black hole (or just
maybe some other varieties of collapsar).  This is a million times or
so greater than any tides associated with Ted's scenario.

In fact, tides aside, a million g in one direction and a million g
(minus 1) in the other would be just exactly as comfortable as
1g would be, no more, no less.  (Of course, it's a tad hard to come
up with a physical scenario to put this to the test, but that's what
the tools we use to model gravity would predict.)

So, forget the "tug of war problem".  It's a non-problem.  Another
objection people often raise that turns out to be a non-problem is due
to Ted's claim that breviparopus massed more than 500000 lbs, but
weighed only 110000 or so. People then object that 110000 is still
above the Holden Limit, so this is not a solution.    They forget that
the Holden Number is H = force / mass^(2/3), so only the numerator is
reduced by the "felt effect".  Indeed, 110000/500000^(2/3) = 17.5 or
so, which is well within the limit.  The problem here is not that the
numbers don't work out (they do) but what Ted mistakes for a weight
estimate is actually a mass estimate, and his own mass estimates are
many times too large.

But don't worry, there are plenty of other problems with Ted's scenario.

Consider for example that the forces required for Ted's scenario
directly contradict the scenario proposed by Rose to explain Pangaea.
And would rip the earth apart, to boot.  Not to mention that Ted
proposes no solution to the "water dilemma".  Nor the problem of
sauropods being restricted to within 2000 miles or so of the pole in
his scenario, when seemingly undisturbed sites are found further away
than that.  Nor the problem that constellations described in the
writings of the time would not be visible from Ted's Pangaea (or would
not move in the sky as they did).  Or any number of the myriads of
other problems that Ted's scenario is heir to.

Or, try this.  Ted once asked (somewhat rhetorically) in response to
the fact that even a planet of Jupiter's mass can't supply a "felt
effect" reduction from far enough away to view Saturn's ring system,
whether the addition of an roughly-earth-sized object perpetually
between earth and the primary would not add enough gravitational pull
to make the scenario work.

The answer is no, it can't.  For the earth-sized planet to be far
enough away to allow a view of the primary, as Ted's scenario requires,
it's gravitation would be something like one tenth that of the primary.
The primary's gravity wasn't strong enough, and another 10% doesn't
fix the problem.

Thus, in addition to Ted's theory contradicting Rose's, it also pretty
directly contradicts Talbott's, since there's no way to get the
required view of the ring system that Talbott interprets the various
mythical accounts to depict.  (Note: though Ted's proposed mechanism
contradicts Talbott's requirement, Talbott himself proposes no
mechanism whatsoever.)

The point is, Ted's notions hang together minimally, and easily pass
such trivial checks as "tug of war" and the like.  But close examination
shows that the peices don't really fit together, often contradict each
other, and numerical models can't be made to work.

( PS: if you were wondering, the apple was the "tug of war" with
      a rope, the orange was the buoyancy of the whale, and the
      bicycle was the gravitational scenario... )
--
Wayne Throop  ...!mcnc!dg-rtp!sheol!throopw