Traveller-digest      Thursday, August 12 1999      Volume 1999 : Number 951



(R)1996. Traveller is a registered trademark of FarFuture Enterprises.
All rights reserved.

The following topics are covered in this digest:

Re: Physics photon question/ Solar Sails
Re: Do the Doggies even bother with clothes?
Re: MREs, Disasters, & SD
RE: Physics photon question/ Solar Sails
Re: HEPlaR vs T-Plates
Re: HEPlaR vs T-Plates
RE: Do the Doggies even bother with clothes?
Re: What's the News on T5?
Re: MT Tasks
Re: Relief for Newbies
Re: HEPlaR vs T-Plates
re: Ethically Challenged Merchants
Fashion victims of the pack (was re: People's Republic of Berzerkely)
Re: Ethically-challenged civilians
Re: What's the News on T5?
Re: AAFES (was: Re: PRB)
Re: Physics photon question/ Solar Sails
Re: Atmospheres #3 : Carbon compounds, allergens, pathogens, &c.
Re: Lagrange points
Re: Skill Resolution (was: Re: MT Task Varients)
Re: Re Clarification of star question

----------------------------------------------------------------------

Date: Thu, 12 Aug 1999 09:08:43 -0700 (PDT)
From: Anthony Jackson <ajackson@molly.iii.com>
Subject: Re: Physics photon question/ Solar Sails

Thing writes:
 
> So the mass of a photon is just an artifact of relativistic movement? It
> doesn't have any mass, but it effects other bodies as if it did?

The 'mass' of a photon is all kinetic energy.

> So does relativistic travel distort space-time to produce this effect?
Huh?  
> 
> And if a particle with no rest mass can only move at the speed of light,
> then why does light move slower through non-vacuums, and really slow
> through Bose-Einstein condensates ?  If photons are truly massless
> particles, it would seem impossible to slow down light, unless you could
> change a photon from massless to a highly energetic, low mass particle.

As I understand it, its because light can't actually go in a perfectly straight line in a non-vacuum -- a refractor effectively increases the length of the path for electromagnetic radiation.

------------------------------

Date: Thu, 12 Aug 1999 12:14:41 -0400 (EDT)
From: Charles Collin <charles@hebb.psych.mcgill.ca>
Subject: Re: Do the Doggies even bother with clothes?

There's a couple of explanations why Vargr might use clothes:  

1) Upright posture leads to male genitals in constant display.  Covering
these becomes important.  This is postulated to be one reason for human
clothing, after all we didn't need the stuff where we evolved either. This
explanation may rely on specifically primate behaviour patterns though,
wherein genital display is a challenge.  One could postulate that some of
those "intelligence genes" put into the Vargr came from humans, so that
similar genital display problems pop up (sorry, couldn't resist :-).

2) Vargr metabolism is slower than in dogs and with their reduced mass,
they might need clothes after all in room temp environments.  

3) For fashion reasons it's easier to switch clothes on a daily (hourly
for some :-) basis then it is to re-dye your fur, string beads and so on.

BTW, from my understanding Vargr don't like garish clothes (strobe
lights!?  :-). They just have different color vision and so their choices
of color combinations often appear garish or muddy to humans (that's a
close paraphrase of the alien module I believe).  They may feel that what
they're wearing is very subdued despite it looking like a jester's outfit
to humans...

Charles C.

------------------------------

Date: Thu, 12 Aug 1999 09:38:52
From: "Douglas E. Berry" <dberry@hooked.net>
Subject: Re: MREs, Disasters, & SD

At 03:59 AM 8/12/99 EDT, you wrote:

>Has anyone ever run a scenerio involving a "natural" disaster?
>Earthquakes, Floods, Volcanoes, Plague, Famine, etc....

Not yet, but Tenalphi/Lunion has a Moon in a decaying orbit that has *just*
reached the Roche Limit.  (This is why a garden planet has no people on it!)

One of the side effects is increased vulcanism.  Ever hear of basaltic
flows?  They're the reason eastern washington state looks the way it does.
Massive geologic upheaval accompanied by ungodly amounts of molten rock.
Blast of superheat steam moving at hundreds of km per hour.

Now, put the PCs in front of that with an air/raft.

Later on, of course, we'll have the breakup of Damolces...
- -- 

Douglas E. Berry       dberry@hooked.net
http://www.hooked.net/~dberry/index.html

People want anarchy for about five minutes. Then they
 want a backrub and some money.  - Bruce Sterling

------------------------------

Date: Thu, 12 Aug 1999 09:58:47 -0700
From: "Thing" <gduke@orca.esd114.wednet.edu>
Subject: RE: Physics photon question/ Solar Sails

On Thursday, August 12, 1999 9:09 AM
Anthony Jackson said,

> The 'mass' of a photon is all kinetic energy.

> As I understand it, its because light can't actually go in a
> perfectly straight line in a non-vacuum -- a refractor
> effectively increases the length of the path for
> electromagnetic radiation.

So the light is still travelling at C, but the route it takes causes it to
cross a much shorter linear distance in a given time, effectively making it
appear slower when measured linearly?

From what I read, I thought that Bose-Einstein condensates work by actually
"cooling" the particles and such.  The following link has a good explanation
of the idea.
http://amo.mit.edu/~bec/intro/intro.html
http://amo.mit.edu/~bec/intro/intro.html#bec

Of course my laymans understanding of Fermions, Bosons, and quantum
mechanics in general is shaky and full of holes.

G.D.D.
======
When you sit with a nice girl for two hours, you think it's only a minute.
But when you sit on a hot stove for a minute, you think it's two hours.
That's relativity.  -Albert Einstein

------------------------------

Date: Thu, 12 Aug 1999 09:50:53 PST
From: shadow@krypton.rain.com (Leonard Erickson)
Subject: Re: HEPlaR vs T-Plates

In mail you write:

> Thad Coons writes:
>
>> No rehash of these points is required. What I would like to know is if any
>> heretic has worked out what kind of power requirements contragrav and
>> T-plates would require if they *didn't* violate conservation of energy?
>> Never mind what they do to General Relativity.
>
> Oh, as a separate issue, you can define T-plates as having a fuel
> requirement of 1 ton H2 per 10,000 newtons (1 ton) per year, in which
> case they don't violate conservation of energy or momentum, though
> they are direct matter->energy converters.  This means a typical
> scout ship (mass 500 tons, thrust 1,000 tons) needs 1000 tons
> H2/year, or 20 tons/week, which is no worse than jump fuel for a
> week.

Sorry, but it isn't that simple. Kinetic energy requires a reference
frame. So does momentum. And in any frame you pick (the ship doesn't
count because it is *changing* velocity) you'll find that the energy
required for a velocity change depends on the velocity you already
have. So it takes *more* energy the faster you go. KE = .5*M*V^2. It's
that V-squared that's the killer.

Reaction drives get around this by imparting energy to reaction mass,
and having that mass start out at rest with respect to the ship. Thus,
if they've got an exhaust velocity of 1 km/sec, they always pay the
energy cost of accelerating the reaction mass to 1 km/sec, rather than
the cost of accelerating the ship from 1 km/sec to 2 km/sec (2^2 - 1^2
= 3) or the cost of accelerating from 2 km/sec to 3 km/sec (3^2 - 2^2 =
5). 
 
- -- 
Leonard Erickson (aka Shadow)
 shadow@krypton.rain.com        <--preferred
leonard@qiclab.scn.rain.com     <--last resort

------------------------------

Date: Thu, 12 Aug 1999 07:49:56 PST
From: shadow@krypton.rain.com (Leonard Erickson)
Subject: Re: HEPlaR vs T-Plates

In mail you write:

> This looks like a subclass of the great done-to-death near-c rock debate,
> but I wasn't around for that. What I have gathered from reading the TML is:
>
> I) Tplates 
>    A) are good because
>       1) They let you do interesting stuff, like fly around in planetary
> systems without worrying about fuel or taking months to get there.
>       2) They have been around since at least MT, and canon says the OTU
> uses them.
>    B) Are bad because
>       1) They violate multiple principles of physics, (most especially
> conservation of energy) which turns them into perpetual motion machines
> that let you do things like launch near-c rocks. 
>
> II) HEPlaR 
>    A) is good because:
>       1) It doesn't break as many physical laws as badly as T-Plates do.
>    B) is bad because:
>       1) You have to carry a lot of extra reaction mass and you are
> severely limited in your ability to move around the system.

It depends on just *how* efficient your drive is. The higher the Isp,
the less fuel you need to achieve the same total velocity change. 

> No rehash of these points is required. What I would like to know is if any
> heretic has worked out what kind of power requirements contragrav and
> T-plates would require if they *didn't* violate conservation of energy?
> Never mind what they do to General Relativity.

The problem is that because theuy don't use reaction mass, T=Plates
*have* to "create" the ships kinetic energy by pushing or pulling on
*something*. That gives you a reference frame to "balance" the enery in.

Alas, it also means that it takes *four* times as much energy to go
from 1 km/sec to 2 km/sec as it does to go from 0 to 1 km/sec. 

In short, the energy budget is exponential with velocity. I can dig out
the equations we worked out for distance and velocity based on a given
time at a constant *energy* expenditure.

It might be practical for getting to/from jump points. But you'd be
sitting ducks for anyone with a decent reaction drive.

- -- 
Leonard Erickson (aka Shadow)
 shadow@krypton.rain.com        <--preferred
leonard@qiclab.scn.rain.com     <--last resort

------------------------------

Date: Thu, 12 Aug 1999 12:04:53 -0500
From: "Moody, Danny M." <DMoody@bridge.com>
Subject: RE: Do the Doggies even bother with clothes?

On Thursday, 12 August 1999 11:15, Charles Collin
[SMTP:charles@hebb.psych.mcgill.ca] wrote:
> There's a couple of explanations why Vargr might use clothes:  

> BTW, from my understanding Vargr don't like garish clothes (strobe
> lights!?  :-). They just have different color vision and so their
> choices
> of color combinations often appear garish or muddy to humans (that's a
> close paraphrase of the alien module I believe).  They may feel that
> what
> they're wearing is very subdued despite it looking like a jester's
> outfit
> to humans...

S'Truth!  Younger, less developed races have trouble processing the dashing
styles that Vargr wear.  What are bold, clashing colors to humans are merely
notes in the melody of visual art of Vargr fashion.

Besides, everybody knows that it's not how you look - it's how you *smell*
that counts!

*sniff**sniff**sniff* Mmmmmm - Arg's Jerky Treats...
*slobber**drool**drool*

Also, is is common that my female Aslan friend in the sensible shoes also
wears flannel shirts?

Oops...

<wham><wham><wham><wham>

 -- vargr1                                              UPP-8D9B85 --
The three principle virtues of a good programmer   |   vargr1@jcn1.com
 are Laziness, Impatience, and Hubris.             | dmoody@bridge.com
             ** Omnia dicta fortiora, si dicta latina. **           

------------------------------

Date: Thu, 12 Aug 1999 17:48:56 +0100
From: SD Mooney <dom@cybergoths.u-net.com>
Subject: Re: What's the News on T5?

trentfs@ix.netcom.com writes:

> Whoo hoo!  This is the best news I've heard yet about T5; I hope it's
>true.  Now that it's safely out of print, I'd like to say this out in the
>open:  T4's game mechanics SUCKED!  They were absolutely god-awful terrible
>and even before the game was out of print I had abandoned them completely.
>The thought that T5 was going to keep this basic framework, no matter how
>modified, made me seriously skeptical about the system.  Now that I know
>there's at least a chance that Marc is going to do the right thing and drop
>that turkey I'll allow myself to become a little enthused.  I'd really like
>a Traveller game system that I can actually use right out of the box
>without having to re-write significant portions of it.

Well, the T4.1 / T5 playtest draft I have seems to be very much a fixed and
updated T4.

I disagree with your opinion on T4; I believe the execution was flawed,
rather than the concept. The manuals were badly playtested, poorly laid out
but it did have the distinction of having one of the fastest and most
effective combat systems in a Traveller game, plus a skill system that
works with the T4.1 fixes (which are actually on the T4 refs screen).

The main work Marc has issued seems to be revisions to skills, character
generation and some concepts for expanding combat. He may of course have
been using a small top secret group to try another complete system, but I
got the impression that the evolution route was the way it was going.

Dom

- ----------Dom Mooney---dom@cybergoths.u-net.com------------
                       MiB - Marines in Battledress
   "Protecting the Imperium from the Scum of the Galaxy"
Rob Prior's Mac software @ http://www.bits.org.uk/ 

------------------------------

Date: Thu, 12 Aug 1999 17:54:47 +0100
From: SD Mooney <dom@cybergoths.u-net.com>
Subject: Re: MT Tasks

"William F. Hostman" <aramis@gci.net> writes:
>PSR is used as psi-point maximum (MT and CT both use PSR to power
>abilities, for the TNE/GT crowds, in a points per use basis, which recovers
>slowly.)

This is the same case in T4.

Dom

- ----------Dom Mooney---dom@cybergoths.u-net.com------------
                       MiB - Marines in Battledress
   "Protecting the Imperium from the Scum of the Galaxy"
Rob Prior's Mac software @ http://www.bits.org.uk/ 

------------------------------

Date: Thu, 12 Aug 1999 17:58:51 +0100
From: SD Mooney <dom@cybergoths.u-net.com>
Subject: Re: Relief for Newbies

 Phil Kitching <postmark.design@btinternet.com> writes:
>>That one has always bothered me. What the Hierate is a "feudal technocracy"?
>Government type 5
>Best bet is to find your way to someone who will sell you
>
>	101 Governments (by BITS)
>
>try www.bits.com (or .org or .co.uk or something)

It's actually:

http://www.bits.org.uk/

BITS products are available through the UK distribution chain.

Overseas customers are advised to order from Steve Jackson Games,
http://www.sjgames.com or Leisure Games in London
http://www.leisuregames.com/ .

All the BITS products are listed at the BITS site on the Products Page....
aside from the ones being released in less than three weeks....


Dom (BITS webmaster)

- -------------Dom Mooney---webmaster@bits.org.uk----------------
                 BITS - British Isles Traveller Support.
 http://www.bits.org.uk/              mailto:bits@bits.org.uk
Traveller is a registered trademark of FarFuture Enterprises.
GURPS is a registered trademark of Steve Jackson Games, Inc.
BITS and CORE are trademarks of BITS UK Limited.
All rights reserved.

------------------------------

Date: Thu, 12 Aug 1999 10:10:51 -0700 (PDT)
From: Anthony Jackson <ajackson@molly.iii.com>
Subject: Re: HEPlaR vs T-Plates

Leonard Erickson writes:
> > Oh, as a separate issue, you can define T-plates as having a fuel
> > requirement of 1 ton H2 per 10,000 newtons (1 ton) per year, in which
> > case they don't violate conservation of energy or momentum, though
> > they are direct matter->energy converters.  This means a typical
> > scout ship (mass 500 tons, thrust 1,000 tons) needs 1000 tons
> > H2/year, or 20 tons/week, which is no worse than jump fuel for a
> > week.
> 
> Sorry, but it isn't that simple. Kinetic energy requires a reference
> frame. So does momentum. And in any frame you pick (the ship doesn't
> count because it is *changing* velocity) you'll find that the energy
> required for a velocity change depends on the velocity you already
> have. So it takes *more* energy the faster you go. KE = .5*M*V^2. It's
> that V-squared that's the killer.

You will note the fuel requirement.  If you convert a ton of hydrogen into energy, you can get one ton-year of thrust.  This is a simple reaction engine which happens to have lightspeed exhaust.

------------------------------

Date: Thu, 12 Aug 1999 09:57:00
From: "Douglas E. Berry" <dberry@hooked.net>
Subject: re: Ethically Challenged Merchants

At 11:59 AM 8/12/99 -0400, you wrote:

>Some of my brothers in the US Army brought "Didi-mau" home with them, they
>learned it from men who had been to Vietnam, it means something
>like "Get out of there". 

"Didi" - Leave, get out, remove
"Mau" - Quickly

This is one of the ones that stuck in the Army.  Soldiers who weren't born
when Vietnam was raging are still saying Didi-Mau.

My favorite was Mox Nix, a corruption of the German Macht Nichts, roughly
"it makes no difference."  You'd see/hear this one in a lot of places.

"Sarge, we've thrown a track!"

"Mox Nix, we don't have to be in position for a few hours."
- -- 

Douglas E. Berry       dberry@hooked.net
http://www.hooked.net/~dberry/index.html

Embrace Fascism.  The uniforms look cool

------------------------------

Date: Thu, 12 Aug 1999 13:26:33 -0400
From: Walter Smith <SmithW@HARTWICK.EDU>
Subject: Fashion victims of the pack (was re: People's Republic of Berzerkely)

Goghuez says:
>>>>>>>>>>>>
        Oh, and by the way...   I wouldn't be caught dead in a had with
strobe lights...  that was out of fashion last year.  It's soft red and rust
phosphorescent inset panels in cuffs, collars and hat brims that are all the
rage on Lair right now....
>>>>>>>>>>>>
Responded to by Ghvourgh, a vargr Corsair:
Oh, so those dead-scents on lair have a monopoly on fashion now?
Of course strobes are out, but you're still using phosphorescence
when you can get enhanced iridescence instead? 
And *everyone* knows that the proper way to do cuffs is puffed,
wide stripes, and **buttons!!!**

Walt Smith

------------------------------

Date: Thu, 12 Aug 1999 10:47:11 -0700
From: "Benyamene' ZeAbe' Akella" <xrp@sierratel.com>
Subject: Re: Ethically-challenged civilians

> IMTU, it will work a few
> times before the screws tighten, and it may work again at some
> future point when the screws loosen.
>
> Might I point out that, IMTU, System A and E, and some of the
> intervening systems are likely in different polities and some of
> those polities might have *no* interest in protecting merchant ships
> belonging to other factions.  Might prefer that merchant ships from
> other polities have problems, but not want to directly provoke a
> war.  Might turn a blind eye to certain activities by certain
> parties... as long as they mind their manners at home.

That is a wad of good points. Yes, I think piracy would be difficult when
deep inside the "mature" 3I, or any other polity with a decent fleet. And
piracy is likely a sporadic affair even at the edges. And I have not read
any canon indicating privateering is at all sponsered by any polity other
than perhaps the Doggy Domains. Which I believe is a very fitting contrast
between uplifted predator/chasers and omnivore hunter/gatherers like
humaniti. And I doubt that this would be the main source of income for
anyone. Ethically challenged merchants indeed, and perhaps even a merc
company that chances on a juicy target, or even a Naval Patrol.
BZA
////////////////////////////////////////
Akella 0609 C654474-6 S kk+ hi++ as+ va+ dr+ da+ so@ zh- vi+  A523
IMTU tc++ ?t4 ru@ 3i+(-) c+ jt au@ st- ls+ pi+ ta@ he+

------------------------------

Date: Thu, 12 Aug 1999 12:53:58 -0500
From: Kenneth Bearden -- Walker Jane Productions <dreamer@brokersys.com>
Subject: Re: What's the News on T5?

SD Mooney wrote:

> trentfs@ix.netcom.com writes:
>
> I disagree with your opinion on T4; I believe the execution was flawed,
> rather than the concept. The manuals were badly playtested, poorly laid out
> but it did have the distinction of having one of the fastest and most
> effective combat systems in a Traveller game, plus a skill system that
> works with the T4.1 fixes (which are actually on the T4 refs screen).

I'll have to agree and disagree here.  I think T4 had some of the best ideas for
Traveller yet...but like Dom says, the execution was poor.  The good ideas were
not well thought out, and the playtesters should have been shot.

On the other hand, T4.1 (or T5 as some say), is just a patch for a system with
bugs.  Marc's fixes seemed like fixes to me, and it made me angry that he was
intent on publishing more shoddy work when he could really put the time into it
and come up with a fantastic system.

So, like Trent, I was never that excited about T4.1/T5.

Bottom line is:  I'd like to see the fantasitc universe that Traveller has be
coupled with a mechanics system that is just as fantastic (and accepted as
playable by veteran role players right out of the box).

As I look at the systems for my next campaign, I'm leaning towards Classic
Trav...although the system is a bit outdated (naturally) without a task system.

I just want something easy, playable, and something that won't take a lot of
time away from the game to Gamemaster.

Kenneth.

------------------------------

Date: Thu, 12 Aug 1999 13:04:42 -0500
From: Black ICE <wombat@premier.net>
Subject: Re: AAFES (was: Re: PRB)

Black ICE wrote:
<<snip>>
> 
> You _do_ realize that I'm going to have to develop an AAFES invasion
> support ship, with ship's boats for roach coaches, and modular cutters
> with the "shoppette" module....
> 
I'm currently designing the "Running Chef" class 10 dton ship's boat,
and I need some input.

Would gut truck food be considered Normal or Meager rations?  While they
seem to fall in the Meager category, I would think that they would have
to be better than combat rations, or they wouldn't sell.  That leaves me
as either defining them as Meager, with combat rations being equivalent
to Emergency rations; or defining combat rations as Meager, and roach
coach food being Normal rations.

I'm leaning toward the first option.... :-P

- -- 
AuricTech Shipyards Journeyman Gearhead
"Gold-Plated [tm] solutions for copper-plated problems!" (r)
http://www.geocities.com/Area51/Shadowlands/9776

------------------------------

Date: Thu, 12 Aug 1999 10:22:48 PST
From: shadow@krypton.rain.com (Leonard Erickson)
Subject: Re: Physics photon question/ Solar Sails

In mail you write:

> There seems to be some very highly educated/knowledgeable people on this
> list, so I thought I would ask a question that has bothered me about photons
> & solar sails?
>
> Solar sails are supposed (AFAIK)to work by harnessing the minute impact
> energy of photons and by virtue of  incredibly light construction and
> massive surface area.  I've heard talk of using lasers to give a solar craft
> a good starting shove out of a solar system.  I can accept all of this.
>
> ......
>
> Except, if photons exert pressure, than they must have mass, albeit very
> minutely.  Photons travel @C so there mass at rest (I you could stop one)
> must be even smaller and amplified by there tremendous velocity.  If this is
> true, then the true limiting speed should be fat above the speed of light,
> as photons must be traveling at a speed where their mass has increased to
> the point where there is no more energy to provide acceleration.

Photons have *zero* rest mass. And they *always* travel at c. But they
also have *momentum* that is proportional to the wavelength of the
photon. The two are linked via Planck's constant. 

And the sail gets *twice* the momentum of each photon. That's because
it doesn't *absorb* them (which would give it the just the momentum),
it *reflects* them. 

You start with a sail with momentum X and an incoming photon with
momentum Y. You end with the photon heading in the opposite direction
(ideal case) and with the same momentum *but in the opposite
direction*. That makes the photon's *new* momentum -Y. And obviously,
the difference bettwen +Y and -Y (2Y) must have been deposited in the
sail if things are going to balance. So the sail winds up with X+2Y.

> Do photons not have mass and photonic pressure is some other phenomenon of
> some energy being converted to kinetic energy?

Photonic "pressure" is due to thier momentum.

> If C is the true limiting speed, and photons do have mass, why are we not
> killed by incredibly massive photons?

The trick has to do with division by zero. 

I won't go into the full argument, but suffice it to say that 0 divided
by 0 can be argued as allowing *any* value as an answer. That's *why*
the operation is "indeterminate".

"current mass" = "rest mass"/tau

At c, tau is equal to zero. And the "rest mass" of photons is zero. QED.

Or to put it another way:

"current mass" * tau = "rest mass"

"current mass" * 0 = 0

Therefore *any* value of "current mass" is perfectly legal. 

- -- 
Leonard Erickson (aka Shadow)
 shadow@krypton.rain.com        <--preferred
leonard@qiclab.scn.rain.com     <--last resort

------------------------------

Date: Thu, 12 Aug 1999 10:37:55 PST
From: shadow@krypton.rain.com (Leonard Erickson)
Subject: Re: Atmospheres #3 : Carbon compounds, allergens, pathogens, &c.

In mail you write:

> Leonard Erickson wrote :-
>> When I was researching alternative respiratory pigments, I recall that
>> there was *specific* mention of cyanide radicas *not* bonding to
>> hemerythin. 
>> 
>> So not only do we have a "taint", we have a *known* means of making the
>> natives immune.
>
> Makes for an interesting bit of chrome, doesn't it?
>
> On Earth, hemerythrin is present in the blood of all sipunculid worms,
> some polychaetes and a brachiopod (Lingula sp.) It's about three times
> the molecular mass of haemoglobin and carries 16 Fe2+ ; it may be immune
> to cyanide attack because the irons are 'protected' by -SH groups on
> nearby amino acid residues.
>
> Sorry about the biological gearheadedness, folks.

Heck, go for it!

As I recall, hemerythin based blood is pale pink in one oxidation
state. But I can't recall which, nor what color the other state is. And
we *do* need to know. After all, we have to be able to tell the players
what color(s) the natives bleed.

- -- 
Leonard Erickson (aka Shadow)
 shadow@krypton.rain.com        <--preferred
leonard@qiclab.scn.rain.com     <--last resort

------------------------------

Date: Thu, 12 Aug 1999 10:42:05 PST
From: shadow@krypton.rain.com (Leonard Erickson)
Subject: Re: Lagrange points

In mail you write:

>         OK, it's not *cancel* out. You're right, there's only one such
> point, the (IIRC) L1 point. Rather, it's points of stability in an
> orbit. Folks feel free to correct me where I stray (especially with
> the numbering). 

As I recall, not even the "L1" point has the forces cancel. The
"equipotential point" is not a Lagrange point.

>         Lagrange points are named after the (French?) mathematician
> Lagrange, who calculated stable points in a limited three-body
> system, where one body is much much smaller than the other two (m3 <<
> m1, m2). For simplicity, I'm going to call the bodies Sun, Earth, and
> Satellite. Earth is orbiting Sun. Those points are:

Most discussions use Earth, Moon, and a satellite. 

>         Stability: Note that only the L1, L4 and L5 points are
> "stable"--that is, if an object in one of them is subject to a
> disturbance that would cause it to move out of the point, there would
> be a tendency for them to drift back in.

I thought L1 was also unstable?

- -- 
Leonard Erickson (aka Shadow)
 shadow@krypton.rain.com        <--preferred
leonard@qiclab.scn.rain.com     <--last resort

------------------------------

Date: Thu, 12 Aug 1999 11:22:54 -0700
From: "Benyamene' ZeAbe' Akella" <xrp@sierratel.com>
Subject: Re: Skill Resolution (was: Re: MT Task Varients)

> I don't expect to convince anyone about this.

You won't have to convince me. I have had the same thoughts, and for more
systems than Trav. The Storyteller system, AD&D NWP's, Twilight 2K, etc. I
don't think the best solution is to shrink the range though. As I said in an
earlier post, I think that some skills may favor attributes, even to that
degree, and others may stress training even more than your solution. Though
not by much, your solution relies heavily on the training.

I think I'll fiddle some numbers today, see if I can do a CT patch for this.
I had a rough one for Storyteller somewhere, but it relied on die rolling
conventions not covered in CT.
BZA
////////////////////////////////////////
Akella 0609 C654474-6 S kk+ hi++ as+ va+ dr+ da+ so@ zh- vi+  A523
IMTU tc++ ?t4 ru@ 3i+(-) c+ jt au@ st- ls+ pi+ ta@ he+

------------------------------

Date: Thu, 12 Aug 1999 10:47:36 PST
From: shadow@krypton.rain.com (Leonard Erickson)
Subject: Re: Re Clarification of star question

In mail you write:

> Looking back over the question I posed regarding stellar evolution I
> realized that it may have been poorly framed.
>
> This is the way it looks like it works to me.
>
> 1)
> Stars begin their lives at the hot (ie bluer, ie B stage)
> or at least toward the blue end of the spectrum.
> as a given star ages it slowly cools down, moving toward the red, or M end.

Nope. Stars do *not* evolve that way. I don't have any of my textbooks
handy, so I can only describe things roughly. 

A star *does* tend to move somewhat on the H-R diagram's "color" axis
as it moves into the "main sequence". But not that much. 

Starts start out "black" and and as they heat up, they'd move from
class M on up *towards* Blue. but only the largest ever get there. Most
never even get out of M. 

This is at first from mere heat of compression as the gas cloud
contracts. At some point fusion begins and the star will expand back
out from photon pressure. It'll brighten and move up the scale some as
it settles down towards its eventual position on the "main sequence".

This position is determined *solely* by mass. The more massive, the
hotter (and "bluer") the star.

Eventually, it'll run out of hydrogen in the core. G\For the lowest
mass stars, that's the end. They'll brighten for a bit from
compression heating as they contract. And eventually, they'll be a
small "white dwarf", cooling slowly over trillions of years.

As I recall, the universe hasn't existed long enough for any of these
stars to run ourt of hydrogen. Remember, low mass stars burn their fuel
more slowly.

Somewhat more massive stars will collapse like this, but in the
process, the core will get hot and dense enough to fuse helium. And
likely also start some hydrogen fusion in layers above *that*. This
causes the outer layers of the start to ballon *way* out. So much so
that the star, regardless of its former class is now "red". A "Red
giant". 

Eventually the helium will run out. And we get another collapse in the
core. If the star is massive enough, this will start fusing some other
element (oxygen?), and likewise trigger helium fusion and ydrogen
fusion in "shells" farther out from the core.

If the star isn't massive enough, it collapses into a white dwarf. 

For increasing stellar masses, the scenario repeats, with heavier and
heavier elements bein fused in the core. Until you get a star that has
iron as the next available "fuel". 

Iron (Fe56) can only be fused (or fissioned!) with *great* dificulty.
And worse, doing so *uses* energy, rather than produces it. So, instead
of the new reactions acting as a spring to cushion the collapse, they
*accelerate* the collapse by tying up energy in producing heavier
elements. This probably produces the "neutrino flash" that precedes the
supernova explosion by many minutes.

So we get a *rapid*, complete core collapse. Possibly down *past*
degenerate matter. And then the layers just above the core, which still
contain fusible elements impact on the new "solid" core. And the heat
and pressure fuses the elements in big buurst. But there's still more
matter falling in, with *enormous* inertia. Eventually, enough pressure
builds to overcome the inertia of the infalling material, and the
overlying layers are blasted away from the core and into interstellar
space. On the way they pretty much wipe out anything else in the
system. 

And the core either cools into a white dwarf, or, if massive enough,
becomes a neutron star. Or maybe even a black hole.

> The stars initial mass will determine how quickly this occurs, and has a
> great bearing on weather the end star product is a black hole, nuetron star,
> or brown dwarf.

Actually, the end points are (in order of starting masss of star):

1. black hole
2. neutron star
3. white dwarf
4. "black" dwarf

Brown dwarves are bodies that were never massive enough to *start*
fusion. A "black dwarf" is a white dwarf that has finally radiated away
all it's remaining thermal energy. Which will take some trillions of
years.

- -- 
Leonard Erickson (aka Shadow)
 shadow@krypton.rain.com        <--preferred
leonard@qiclab.scn.rain.com     <--last resort

------------------------------

End of Traveller-digest V1999 #951
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