From: "Dan'l Danehy-Oakes" 
Subject: RE: (urth) Leagues and gravity
Date: Mon, 11 Mar 2002 16:10:49 -0800

Jerry Friedman wrote, and I'm going to snip and cut mercilessly to
avoid a 90% quoted posting...

> I can hardly imagine Green has less than half the gravity of Earth
> and the same density ... 1/8 the Earth's mass.  

> Let's also believe Incanto quoting one Gagliardo when he says the
> closest approach of Green to Blue is 35,000 leagues.  ... that's 
> 105,000 miles ... Green's closest approach is about 1.87 x 10^8 m.

> ... the maximum force that Green exerts on Blue at conjunction is about
> 8.5 x 10^21 N. Green is going to mess up Blue's orbit something fierce

> I doubt the system would be stable for more than one or two 
> conjunctions.

> So did I make a mistake?  

Not, so far as I can tell, in your math.

> Are we supposed to infer something from this discrepancy?  

Possibly. My immediate guess would be that Gagliardo was actually
clueless about the actual distance between the two worlds at, uh,
perigreen. (No falcon around about this.) It's probably safe to 
guess that the astronomy and astrophysics of the Short Sun
colonists is pretty primitive.

> Or is this another case of Wolfe's not letting science get in
> the way of the story?  

This is probably heretical, given his engineering background and
almost fanatical attention to detail, but ... I have never really 
thought of Wolfe as the kind of Clement-ish worldbuilder who sits 
down and calculates all the astrophysics of a system before he 
starts writing. In fact, I could be wrong, but I'm pretty sure 
that this is the first Lupine text where the actual mechanics of a 
star system really affected the plot in any significant way - 
certainly the mechanics of the St Croix system isn't very germane 
to the plot of _Fifth Head_!) 

> The problem with the latter is that if he can get away with
> anything, the kind of deductions he apparently expects readers
> to make become problematic--which is the difficulty we're
> having with the Blue/Ushas conjecture.

The problem we're having with the Blue/Ushas conjecture is that
some people on this list, who shall go nameless, like the idea
so much that they will hang on to it in the face of any amount
of contradictory evidence. Heck, _I_ like this theory. It would
resolve a number of irritating problems in the Sun books. But
in fact it simply does not work for eighty-'leven reasons.

--Blattidio


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