Subject: Re: (urth) chems on Urth and a FTL Whorl

From: James Wynn <crushtv at hotpop.com>
Date: Sat, 16 Aug 2003 17:50:29 +0000

Ash said:
Chems wouldn't be found on Urth at all if they were invented on board the
Ship. Reference Sidero's claims concerning this. Jonas was an exception, and
he clearly came from the Ship rather than Urth.

Crush responds:
Are you saying that the lack of chems in tBotNS is an argument that they all
from "the Ship"? But Marble originated on Urth -- in tBotLS she says she saw
the original Short Sun. And Kypis seems to recall them on Urth.

Don said:
I'm not qualified to debate this but I think the general consensus is
that the Whorl was a sub light speed ship.  But I personally think it
somehow attained light speed or greater at some point.

Crush responds:
I think the argument is that a generational ship is unnecessary for a FTL
ship. If it can travel at the SoL, then any trip would be instantaneous for
the passengers.

-- Crush

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From: matthew.malthouse <matthew.malthouse at guardian.co.uk>
Date: Mon, 18 Aug 2003 09:10:51 +0000

>ship. If it can travel at the SoL, then any trip would be instantaneous 
for

Nit-pick.  Any part of the voyage at the speed of light would be 
instantaneous for the passengers.

Any requirement for acceleration to or deceleration from that speed would 
occasion subjective duration for those aboard.  Viz the light-huggers of 
Alastair Reynolds trilogy.

More "speed of light" isn't sufficient.  A 30 light year journey would 
still take minimum 30 years in the external time frame.  Practically 
speaking to make interstellar travel no more an obstacle to empire than 
say sailing across the Atlantic would require superluminal travel and I'm 
not sure we even have a theory to suggest what subjective duration would 
be for those concerned.

Matthew

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From: Michael Buice <mabuice at uchicago.edu>
Date: Mon, 18 Aug 2003 15:44:38 +0000

On Monday, August 18, 2003, at 04:10  AM, 

> Alastair Reynolds trilogy.

Strictly speaking there are only technological barriers preventing the 
subjective duration from being as small as desired.  Practically 
speaking, however, I can only offer a "yup, what he said."   
Acceleration would be the difficult engineering feat.

> not sure we even have a theory to suggest what subjective duration 

We do, however, have a theory that says superluminal travel completely 
wrecks causality.  To my knowledge, no satisfactory solution outside 
polysyllabic vociferation or invoking General Relativity in weird and 
clever ways is known.

Michael

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From: James Wynn <crushtv at hotpop.com>
Date: Mon, 18 Aug 2003 18:05:02 +0000

Matthew Malthouse wrote:

Then Michael Buice wrote:

Crush seeks clarification:
Okay. Are ya'll saying that a generational ship *would* be required for FTL
travel?

Either way, the One Ship theory would not be bolstered since it would
require endless more groundless hypothesizing to imagine why the Cargo
should be transported generationally on Tzadkiel or why it would take
hundreds of years for them to arrive. Or how the ship got so out of control
that orbited the Green/Blue system for 30 years without unloading the Cargo
and why it hung around the system for another 30 years after unloading.

But... it would not prevent a my posit that the Whorl *could* be the
primitive, infantile Tzadkiel. OTH that sort of theory is helped mostly by
limited information, because of the inclination to recycle and re-rig the
data available.

-- Crush

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From: Michael Buice <mabuice at uchicago.edu>
Date: Mon, 18 Aug 2003 18:59:14 +0000

> Okay. Are ya'll saying that a generational ship *would* be required 

Completely orthogonal question.  I'm saying that with sufficient 
technology to deliver large amounts of power, the generational starship 
is no longer a realistic story.  Although it will seem as if 30 years 
have passed to any proverbial "Typhon" back on Urth, the ship can 
travel such that the entire trip takes as few as a couple of seconds to 
the passengers, acceleration and all.  This is essentially a 
combination of time dilation and Lorentz contraction (and needs a 
geodesically complete space-time, but nevermind that).  Realistically, 
one would imagine some compromise wherein the generational starship 
makes more sense and is essentially a big rock traveling at constant 
velocity through space, not fast enough that the passengers won't still 
experience a great deal of time (as the, I believe, 500 years or so 
suggested in Long Sun).

For clarity, all of this is subluminal.  Superluminal travel, as I said 
before, completely wrecks causality and should be left to fuzzy logic 
and "heavenly" Ships.  Put it another way, Tzadkiel (or whoever 
designed the Ship) would have to know more physics than I do (says the 
physics grad student).

Michael

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From: matthew.malthouse <matthew.malthouse at guardian.co.uk>
Date: Tue, 19 Aug 2003 07:03:40 +0000

>polysyllabic vociferation or invoking General Relativity in weird and

*Waves Magic Wand*

Father Inire's mirrors side-step all these issues.

Matthew

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From: matthew.malthouse <matthew.malthouse at guardian.co.uk>
Date: Tue, 19 Aug 2003 07:54:27 +0000

>Okay. Are ya'll saying that a generational ship *would* be required for 
FTL

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

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

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

So to get to our closest neighbour, Proxima Centauri which is 1541 light 
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 
frame

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

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

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

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

Matthew

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