Archive-Message-Number: 2077
From: Mark F. Cook <markc@hpcvss.cv.hp.COM>
Subject: I should look before I leap...
Date: Tue, 15 Jan 91 11:08:57 PST



Based on my subject line, maybe I'd better start running Vargr
characters. :-)



Regarding my post about black globed ships slamming into planets and
overloading, I guess I should have read a bit further into the MT BBS
on GEnie before proposing MY brilliant inspiration, to wit:



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

Category 11,  Topic 10

Message 194       Sun May 13, 1990

M.MIKESH                     at 16:53 EDT



 Subject: Black Globes



 Joe -

      <Of course, one thing everyone has been assuming is that the
 ship/energy sinks onboard the space vessel with the black globe could
 absorb all this energy that the vessel gathered when it entered an
 atmosphere.>

      True.  We've just been talking in theory so we can develope a
 better understanding of what's going on.

      <In actuality, I see the energy sinks of the owning vessel going
 into an overload condition if it enters a world's atmosphere.>

      You're right.  I just ran through the equations, and what I found
 was that the energy in de-orbiting and that which a J-1 ship could
 absorb was well over 10 million times in difference.
      The scarry thing about this was that the lion's share of the
 energy was in the form of potential energy ( E=mgh ).  This means that
 a globed ship had best stay away from a planet.  A slight change in
 depth to a gravity well could spell doom.

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



Well, at least it's nice to know I think along the same lines as the MT
designers, huh?



                "Here's the next plant for your collection, Turin.  It's
                 a Pharosian Bitching Cactus.  Where do you want it?"
                        "...MY NEEDLES ARE TOO DRY...MY POTTING SOIL
                         ISN'T SANDY ENOUGH...THIS POT IS TOO SMALL,
                         I'M GETTING ROOT-BOUND...IT'S TOO DARK IN HERE..."

                "...put it in the airlock."

                                [paraphrased from my MT campaign]

Later,


        Mark F. Cook



USMail: User Interface Technical Support
        Hewlett-Packard - Interface Technology Operation
        1000 NE Circle Blvd.  Corvallis, OR 97330

INTERNET: markc@hpcvss.cv.hp.com
          markc%hpcvss.cv.hp.com@relay.hp.com

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

Archive-Message-Number: 2078
Date: Tue, 15 Jan 91 23:12:13 -0900
From: George William Herbert <gwh@soda.Berkeley.EDU>
Subject: Black Globes


hrm.  The material in Knightfall (information about a sneak-attack planetary
assault from black-globed ships) tends to indicate that Gravity does indeed 
affect ships in Black Globes.

- - -george

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

Archive-Message-Number: 2079
Date: Wed, 16 Jan 91 21:55:29 GMT
From: grue@batserver.cs.uq.oz.au
Subject: Black Globe ideas

>Date: Tue, 15 Jan 91 10:28:51 PST
>From: Mark F. Cook <markc@hpcvss.cv.hp.COM>
>Subject: (2075) Black Globes redux


>B)  Any solid striking a black globe will demonstrate all the properties
>    of a perfect inelastic collision, with all the kenetic energy tranferred
>    to the globe.  The only thing the occupants of the globe would notice
>    is an energy raise in their capacitors.

This would make black globes next to useless against incoming missiles.
Think of the KE that a missile that has been accelerating for 20 minutes
at 6Gs.  I would assume that 6Gs would have to be a minimum for a missile
and 20 minutes is a combat round!  A standard HE missile has a weight of
0.05 Tonnes which is 50 kgs.  g = 9.8 m/s/s so 6G = 58.8
for a time of 20*60=1200 seconds.

v = v0 + a.t = 0 + 9.8 * 1200 = 70600m/s

            2                                                    11

ke = 0.5 m v  = 0.5 * 50 * 4984360000 = 124609000000 = 1.246 * 10   J



Is that a big number or what!  Splat goes one space ship!



Just think what a small suicide fighter would be capable of (the perfect
place to use a robot pilot --- while attacking black globe shielded
ships).


Worse, since mass is energy (E=mc^2), wouldn't the globe have to absorbe
the energy of a mass placed in contact with it?


I hope I got the above figures correct, I never was much good at physics.
I'm sure somebody on the list will correct me when I'm wrong.

							Pauli

seeya


Paul Dale               | Internet/CSnet:            grue@batserver.cs.uq.oz.au
Dept of Computer Science| Bitnet:       grue%batserver.cs.uq.oz.au@uunet.uu.net
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f4e6g4Qh4++             | JUNET:                     grue@batserver.cs.uq.oz.au


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

Archive-Message-Number: 2080
From: Adrian Hurt <adrian@cs.heriot-watt.ac.uk>
Subject: Re: Black globes and gravity
Date: Wed, 16 Jan 91 13:08:26 GMT


Mark F. Cook <markc@hpcvss.cv.hp.COM> writes:

> 
> A)  Black globes cut off gravity.  If you turn one on while in orbit
>     around a large body (i.e. planet), you suddenly take off in a straight
>     line, tangetial to that body.


Does the theory about gravitons apply in Traveller?  If so, how's this for
a perpetual motion machine?



1. Vehicle with black globe sits at a certain height.  Globe is off.  Vehicle
falls.
2. Vehicle switches on its globe.  Vehicle now takes off as described above,
and also absorbs the gravitons.
3. Vehicle shuts off globe, uses some of the energy absorbed to move along
back to its previous position, and beams the rest at the planet.
4. Go to 1.



In another article, Mark F. Cook <markc@hpcvss.cv.hp.COM> writes:
>       You're right.  I just ran through the equations, and what I found
>  was that the energy in de-orbiting and that which a J-1 ship could
>  absorb was well over 10 million times in difference.
>       The scarry thing about this was that the lion's share of the
>  energy was in the form of potential energy ( E=mgh ).  This means that
>  a globed ship had best stay away from a planet.  A slight change in
>  depth to a gravity well could spell doom.



How far away must it stay from the planet?  The further it gets away,
the more potential energy it gains, as h in the above equation gets
bigger.  Meanwhile, it's losing potential energy as it gets closer to
something else, e.g. a star 2 parsecs away.


- - -- 

 "Keyboard?  How quaint!" - M. Scott



 Adrian Hurt			     |	JANET:  adrian@uk.ac.hw.cs

 UUCP: ..!ukc!cs.hw.ac.uk!adrian     |  ARPA:   adrian@cs.hw.ac.uk



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



Archive-Message-Number: 2081

Subject: Re: 2075-2077 Black Globes

Date: Wed, 16 Jan 91 9:20:15 PST

From: wrgate.wr.tek.com!agora.rain.com!carlf@tessi.UUCP (Carl Fago)


Mark quoted from Genie:
> Then there's the famed "Black Globe World" in the Vargr Extents. On that world
> (Tuglikki 0904), a Vargr researcher activated a black globe and it promptly
> expanded to engulf a radius of 50 km from its location within 24 hours. That
> was in 973 (Imperial). That black globe engulfed the entire world within a
> year and kept growing, although at a slower rate. The black globe has reached
> 20,000 km in size and continues to grow at a rate of about 20 km per standard
> year.  In about 2 trillion years, assuming the globe's rate remains constant,
> it will have engulfed all of charted space. Recently, however -- for some
> unknown reason -- the globe's expansion rate has been increasing dramatically.
> Many researchers theorize this increased expansion rate means the globe is
> about to "go into overload." A globe of this size, if it releases all of its
> aborbed energy in one sudden blast, would devastate the entire parsec (both
> star systems).


Now the question comes up about what happens to gravity with black globes
and what are the effects?


I propose that a black globe reduces any factor of "g" (the gravitational
constant) from external bodies, to zero.  This makes any black globe
maintain its proper motion with respect to the universe at large.  Thus this
Vargr black globe would not be staying in Tuglikki 0904 but would be
travelling at some velocity (probably large) depending on the proper motion
of the star system it is in, depending on the proper motion of the galaxy,
and depending on the proper motion of the galactic cluster!


So the question you have to ask yourselves is, "Is it heading my way and
can I sell my property before it gets here or someone else finds out!!!"



> M.MIKESH                     at 16:53 EDT
> 
>  Subject: Black Globes
> 
>  Joe -
>       <Of course, one thing everyone has been assuming is that the
>...
>       <In actuality, I see the energy sinks of the owning vessel going
>  into an overload condition if it enters a world's atmosphere.>
>       You're right.  I just ran through the equations, and what I found
>  was that the energy in de-orbiting and that which a J-1 ship could
>  absorb was well over 10 million times in difference.
>       The scarry thing about this was that the lion's share of the
>  energy was in the form of potential energy ( E=mgh ).  This means that
>  a globed ship had best stay away from a planet.  A slight change in
>  depth to a gravity well could spell doom.


And I would have to disagree with the designers on this point.  Potential
energy would have no effect (or at least it would if one assumed my
previous point of reducing external gravitational constants to zero.)
Hence g=0 thus E (potential) = 0.  Now the kinetic energy traveling
through the atmosphere is another matter all together and I am in 
agreement...don't travel to a planet's surface with your black globe
on!


                     *-=Carl
		     carlf@agora.rain.com


Archive-Message-Number: 2084
Date: Wed, 16 Jan 91 14:04:08 PST
From: wilber%nunki.usc.edu@usc.edu (John Wilber)
Subject: Black Globes again


Many of you mentioned the possibility of overload with a black globe
contacting several solid objects, bumping into large planets, and so
on.  The ancients solved this problem by finding a way to create a
large, nearly infinite "energy sink."  This is mentioned in Adventure
13 from the old Traveller books.  I forgot what the title of the book
was, but I do remember how they made the "sink."  I'm not giving any
more detail here so I don't spoil the adventure for somebody else, but
if you want to know, mail me at wilber@nunki.usc.edu.


John
wilber@nunki.usc.edu



Archive-Message-Number: 2086
Date: Thu, 17 Jan 91 01:30:14 -0600
From: bonnevil@acc.stolaf.edu
Subject: Re: (2081) Black Globes


I hate to duck into these techno debates, but I have a few questions and/or
comments about this one involving the force field generator.

>I propose that  a black globe reduces any factor of "g" (the gravitational
>constant) from external bodies, to zero.  This makes any black globe
>maintain its proper motion with respect to the universe at large.  Thus this
>Vargr black globe would not be staying in Tuglikki 0904 but would be
>travelling at some velocity (probably large) depending on the proper motion
>of the star system it is in, depending on the proper motion of the galaxy,
>and depending on the proper motion of the galactic cluster!


Ummm, proper motion relative to what frame of reference?  I vaguely
recall something from freshman physics that there is no universal frame
of reference...proper motion is always relative to _something_, and
I vaguely recall that this something can be picked arbitrarily.  There
shouldn't be a universe at large frame of reference then, right?
Maybe I'm wrong -- one of you physics majors might want to jump in here.


[Right on, in Einsteinian General Relativity, all frames of reference
are valid - there is no "master" frame of reference.  The Universe's
rules apparently hold true for all observers, and there is no underlying
"grid" or "mesh" to the Universe that is special or fixed.  All events
in the Universe happen relative to each other.  Nonetheless, there are
several holes in EGR in Traveller.  Perhaps there is a non-relativistic
universal frame of reference available through a small oversight in
Einsteinian theory.  How else can you suspend your disbelief that matter
can travel faster than light? That reactionless thrusters can function?
How many holes and hand-waving you permit in your campaign is a function
of the Player's and Ref's ability to suspend their disbelief.  -- James]

Another question for physics majors...can the PE problem be gotten rid of
if the potential energy of a system involving a large body and a bg'ed
ship is set at zero for the ship arbitrarily, and the PE is assigned to
the planet whose gravity the ship is falling into?  Then the ship would
just have to worry about the KE when the planet hit it, right?  (Sort
of thinking about the problem backwards.)  It's been a while, so I may
be missing something important here....but if that works, maybe it solves
the problems about approaching planets.


Personally, if I was using a globe, I'd be worried about KE weapons --
but then, it might be a bad idea to have it on a high rate of flicker
if I thought they knew where I was.  Then again, if it can nail the
capacitors, it can probably get me anyway!


- - --Steve

Archive-Message-Number: 2089
From: Adrian Hurt <adrian@cs.heriot-watt.ac.uk>
Subject: Re: Black globes being hit by missiles
Date: Fri, 18 Jan 91 10:14:16 GMT

grue@batserver.cs.uq.oz.au writes:
> >From: Mark F. Cook <markc@hpcvss.cv.hp.COM>
> >Subject: (2075) Black Globes redux
> 
> >B)  Any solid striking a black globe will demonstrate all the properties
> >    of a perfect inelastic collision, with all the kenetic energy tranferred
> >    to the globe.  The only thing the occupants of the globe would notice
> >    is an energy raise in their capacitors.
> 
> This would make black globes next to useless against incoming missiles.
> <Assume a 50 kg missile has been accelerating for 20 minutes at 6G.>
>
> for a time of 20*60=1200 seconds.
> 
> v = v0 + a.t = 0 + 9.8 * 1200 = 70600m/s
		 0 + 9.8*6*1200 = 70560 m/s

>             2                                                    11
> ke = 0.5 m v  = 0.5 * 50 * 4984360000 = 124609000000 = 1.246 * 10   J
> 
> Is that a big number or what!  Splat goes one space ship!

Two points.


First, that assumes that the target ship isn't moving.  If the target takes
any evasive action, some of that acceleration is going to be used up following
the target.  Second, if the target is moving towards the missile at the time of
impact, the target's velocity gets added to the missile's velocity; if the
target is moving away from the missile, the target's velocity gets subtracted.


However, these figures will probably do for an order of magnitude analysis.


The MT Referee's Manual says that 1 kilolitre of capacitors can absorb 650 MW
of energy.  Which just shows what a heap of junk the MT Referee's manual is -
MW is power, not energy.  If 1 kilolitre of capacitors can absorb energy equal
to 650 MW coming in for one full turn, i.e.

        6                 11
650 * 10 * 1200 = 7.8 * 10   J

then that kinetic energy will hardly be noticed.  It all depends on how long
that 1 kilolitre of capacitors can absorb 650 MW.


- - -- 
