Leagues and gravity

Grant Peacock · 12 Mar 2002, 00:49 · from urth-v0203.mbox · original

This is the message as the crawl holds it, before anything here touched it. What the conversation shows has been through ingest: transfer encodings decoded, attachments dropped, quote markers repaired, and the archiver’s ? resolved into quotation marks and dashes. Those repairs are judgements and some of them are wrong, which is what this page is for. Email addresses are obscured here as they are everywhere else on the site, so it is before our repairs rather than byte for byte.

From: Grant Peacock <grantpeacock at yahoo.com>
Subject: Re: (urth) Leagues and gravity
Date: Mon, 11 Mar 2002 16:49:37 -0800 (PST)
Message-ID: <urth-v0203-327 at digest.urth.net>
X-Urthmirror-Source: http://www.urth.net/urth/archives/v0203/327.txt.shtml
MIME-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: quoted-printable


> Anyway, you got me thinking about Green-Blue celestial mechanics.  Stop
> me if this has all been done.
Yeah I once posted some similar thoughts, although I didn't do any math.

Have you considered the possibility that the narrator is accustomed to grav=
ity
less than 1 g?  I'm assuming the whorl was designed to prepare people for B=
lue.=20
The fliers in the whorl are perhaps more realistic in a .5g environment.

Our moon exerts a stronger force on Earth than our Sun does.  I say this be=
cause
tides are only a bit more extreme during a full moon.  (I forget the termin=
ology.=20
What are neap tides??)  So I would guess there must be something wrong in y=
our
calculations.=20

I think you are surely right that the orbits are unstable, even if the force
exerted by Green on Blue is a small percentage of that exerted on Earth by =
the
moon.  This means that the arrangement is a new one.  For those who believe=
 the
Blue=3DUshas theory, what must have happened was that the white fountain gr=
abbed
Lune out of orbit as it came lumbering in and made into a planet.

Does the white fountain literally move through space into the system, or do=
es it
just magically appear?

>=20
> We're pretty sure Green is not a satellite but rather another planet
> with a slightly smaller orbit, so that it comes into conjunction
> every six years (if I remember correctly), right?  Also, Green has
> higher gravity than the moon--otherwise the narrator would have told
> us at least once how the first thing he as Horn noticed was floating
> every time he tried to take a step.  I can hardly imagine Green has
> less than half the gravity of Earth and the same density.  Using those
> assumptions gives it 1/8 the Earth's mass.  (Calculations available on
> request.)
>=20
> Let's also believe Incanto quoting one Gagliardo when he says the
> closest approach of Green to Blue is 35,000 leagues.  If these are
> the same leagues in the afterword to _The Sword of Lictor_, namely
> about three miles, then that's 105,000 miles.  For comparison,
> somebody on the first visit to the Red Sun Whorl says a league is
> 7000 steps.  If these are half the Roman pace of which the 5000-foot
> Roman mile was a thousand, then that's 7000*2.5 =3D 17,500 feet ~ 3.31
> miles.  Using that latter number, Green's closest approach is about
> 1.87 x 10^8 meters.
>=20
> We can now determine that the maximum force that Green exerts on Blue
> at conjunction is about 8.5 x 10^21 N.  For comparison, the force the
> sun exerts on the Earth is about 35.3 * 10^21 N.  In other words,
> Green is going to mess up Blue's orbit something fierce--and much
> more if it has more than half the Earth's gravity.  Mere storms and
> tides are nothing.  Blue is going to mess up Green's orbit even more.
> I doubt the system would be stable for more than one or two
> conjunctions.
>=20
> So did I make a mistake?  Are we supposed to infer something from this
> discrepancy?  Or is this another case of Wolfe's not letting science
> get in the way of the story?  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.
>=20
> Jerry Friedman
>=20
> __________________________________________________
> Do You Yahoo!?
> Try FREE Yahoo! Mail - the world's greatest free email!
> http://mail.yahoo.com/
>=20
> --=20


__________________________________________________
Do You Yahoo!?
Try FREE Yahoo! Mail - the world's greatest free email!
http://mail.yahoo.com/

--=20

An unofficial mirror of a public mailing list · about & removal requests · download the archive · before the list · original archive at urth.net