chems on Urth and a FTL Whorl

matthew.malthouse · 19 Aug 2003, 07:54 · from urth-v0308.mbox · original

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From: matthew.malthouse at guardian.co.uk
Subject: Re: (urth) chems on Urth and a FTL Whorl
Date: Tue, 19 Aug 2003 08:54:27 +0100
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>Okay. Are ya'll saying that a generational ship *would* be required for=20
FTL
>travel?

No.  But there would likely be a minimum duration involved.

To make things simple assume a Newtonian universe and that the ship=20
accelerates at 1 g - ie in your cigar-with-fins space ship the nose goes=20
forward and the decks are perpendicular to the axis of the ship=20
experiencing a comfortable 1 "gravity"

If a "starship" accelerates at a rate of 1 G , its speed is increasing by=20
10 m/sec each second. If we divide the speed of light, 300,000,000 m/sec,=20
by 10 m/sec^2, we find that the time to reach the speed of light is 347=20
days.

So to get to our closest neighbour, Proxima Centauri which is 1541 light=20
days away you have

    347 days accelerating
    1194 days cruising at the speed of light
    347 days decelerating.

that's 1880 days or five years and two months.   In the external time=20
frame

Now the universe isn't Newtonian but I don't have the maths to work out=20
the relativistic effects.  However simplest case, at the speed of light=20
there is no duration so (crudely ignore the acceleration phases) the=20
travelers don't experience those 1194 days cruising so internally on the=20
space ship it's something approaching  690 days.  [and I have also=20
entirely ignored the fact that at tSoL mass is infinite and would require=20
infinite energy to accelerate to it]

Certainly a generation ship is not required, just something large enough=20
that the passengers don't go mad.=20

With such a means of transport the establishment of colonies would be=20
eminently practical.  But I seriously doubt that an effective empire could=20
be maintained once those colonies were productive.  If it takes more than=20
10 years to send an envoy to the closest star and back political control=20
will fail.

Sidebar:  thinking about this it occurs to me that Severian experiences=20
decks with useful gravity _parallel_ to the axis of movement of The Ship=20
Tzadkiel but I can't recall any indication of noticing the Ship's forward=20
motion/acceleration.  If that is below the threshold of perceptibility=20
then it's low and attaining the speed of light would be inordinantly long=20
- unsurprising for a light-sailing vessel.  Yet although aboard some time=20
- long enough to re-write his manuscript - it doesn't seem to me that it=20
was a remarkably extended voyage so I'd have to conclude the Tzadkiel does=20
not rely on attaining the speed of light in order to either travel in time=20
or make the crossing between Briah and Yesod.  Therefore there must be a=20
mechanism that is both esoteric and hidden from him (and us).  I don't=20
think there is any adequate explanation of Tzadkiel to be had, a wand has=20
been waved.  That being the case I suspect that it is entirely reasonable=20
to assume supra-luminal space-flight for the Empire of Man as an=20
inexplicable given - perhaps the backswing of the same wand.=20

Matthew

--=20

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