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Grex Scifi Item 62: Space ships, and how they work
Entered by drew on Sun Jul 23 21:15:44 UTC 1995:

"Beam me up, Scottie!"
"Lock Phasers on target."
"Ahead Warp factor two."
"Eye Eye Captain"

    Nothing has so thoroughly captured my imagination as the concept of
the vehicle-that-can-leave-the-world. I have watched many TV series and
movies featuring these wonderous machines, from the relatively decent
to the downright cheesy, and eventually took up the task of learning
their workings. Viewed in the light of the new knowledge, these shows,
including that staple of space fiction _Star Trek_, were found wanting.
It seems that the writers of TV shows don't often bother to learn about the
subject on which they're writing. Or, as has once been commented to me,
"*somebody's* warped!"

    This item will deal with a few of the major beefs I have with TV
space shows, and how they should be rewritten.


Scale and speed:
    Space is *huge*. Nearby planets are hundreds of millions of miles
apart, and the Outer planets are in the billions of miles distant. This
is between 10,000 and 100,000 times the diameter of Earth. Covering these
distances, and for that matter even getting out of a gravity well, involves
speeds measured in miles per second. What this means is that spacecraft,
particularly in combat with one another, will spend most of their time too
far apart to track each other visually.
    Consider two StarDestroyers measuring about a mile in length, in orbit
around Earth moving in opposite directions; and suppose that they are
oriented so as to expose the maximum of surface area to each other. Since
Earth low orbital speed is about 5 miles a second, the two ships will
pass each other at 10 miles a second. Human visual resolution is around
35 seconds of arc; so, providing that the ships are well illuminated, they
should be just barely visible to each other when about 6000 miles apart -
10 minutes travel time relative to each other. Seeing enough detail to
tell that it's a StarDestroyer will require them to be much closer together,
about 600 miles (1 minute of travel time) or possibly even less. A twenty
foot long fighter craft will be *much* less visible. You're not going to
be able to see it *at all* until it's 22 miles away, and about 2 seconds
from impact.
    Thus in most interactions between ships, especially in deep space,
you shouldn't be able to see *squat* just by looking out a window.


Communication:
    The scale of distances will even have an effect on communications. The
presence of instantanious communications in every sci-fi series has been a
continuing disappointment; a radio message will take a very noticeable
amount of time to get to its recipient. Communications can be near normal
as far as the Moon. However, communicating with Mars will involve several
*minutes* of waiting for each reply. And while M-net's MSEN connection has
been known to operate like this, it will make communication very different
from how it's usually shown.
    In fact, *any* information that a ship receives is going to be out of
date in proportion to the distance it has traveled. This includes radar
and visual sightings, and it will have a definite effect in combat. At best,
you would be seeing where the target was when the light or radar reflection
left it. By the time the information arrives, the target will have had plenty
of time to move around; not to mention the time it will take for your shot
to get there.
    Out further than 100,000 or 200,000 miles, a laser beam, or any kind of
attack which cannot change course on the way, is going to be ineffective. The
only weapon which will have a chance is a guided missile.


Motion:
    In space, everything moves and keeps moving. If it didn't, everything
would immediately collapse into a gigantic black hole. Ships move, and
getting somewhere involves changing the motion. The known modes of ship
movement are basically two types: ballistic and accelerative. In the former,
the engines are fired for some nominal amount of delta-V, and the ship
coasts to its destination, where the ship is turned and the engines fired
in the opposite direction (or else reverse-mounted engines may be used) to
match speeds with the destination. The latter type involves running the
engines constantly, turning the ship around at the midpoint of the trip.
    Whereas a car, plane, or watercraft has a maximum speed and range, a
spacecraft has a maximum *acceleration*, generally expressed in gravities;
and a maximum *delta-V*, which is the total amount of speed change that
full fuel tanks will allow.
    _Babylon 5_, and the _2001_ movies, have this part right. All the
others seem to treat spacecraft as air or ground vehicles, slowing to a
stop whenever the power is shut off.


Fuel:
    The _Enterprise_ never seems to need refueling; the "dilithium crystals"
somehow being able to recharge themselves. Several fist-sized glass cubes
provide a seemingly infinite amount of energy. The ships in the _Star Wars_
movies *never* refuelled, and nowhere were fuel requirements even hinted at.
    In fact, even with total conversion of matter to energy, starships will
likely need frequent refueling, probably at every stop. Even changing vectors
within a solar system will take measurable amounts, let alone boosting to
relativistic speeds. Expect mass ratios much greater than unity.
    Fortunately, exotic and expensive materials like "dilithium crystals"
probably won't be necessary. The most likely fuel will be an isotope of the
most common substance in the universe - hydrogen. Deuterium is available
anywhere there's water, and would also be present in the atmospheres of gas
giant planets like Jupiter and Saturn.
    Ordinary hydrogen is even more plentiful, and can be used in a fusion
engine if a few catalysts are added to the reaction. Since hydrogen atoms
occur in small quantities throughout interstellar space, a catalysed fusion
engine can be fueled en route at low relativistic speeds (0.1C to 0.8C) if
a magnetic field can divert protons from far enough away from the ship. Such
a collector could also double as a screen to protect the ship from the
incoming proton radiation.


Combat:
    My major complaint here is with the depiction of "lasers" whose output
is visible from the side, and in many cases is noticeably slower than light -
in fact, slower even than a bullet. While a powerful enough laser can be
useful against ships or missiles, all that will be visible is a burning spot
of light on the target, especially in a vacuum.
    A couple of other things are either ignored, or else when used, do far
less damage than they should. They are collisions and engine exhaust.
    A quick calculation will show that a moderate sized ship which crashes
into a starport at orbital speed will have enough kinetic energy to obliterate
the starport. If the collision is at a significant fraction of lightspeed,
very little mass will do a great deal more damage.
    Drive exhaust is similarly deadly. Any engine efficient enough to be useful
for interstellar travel is going to have a lot of power per unit thrust.


Gravity:
    There are times when there *should* be gravity inside a spacecraft.
Whenever the engines are firing, for example, there will be what seems
to be a gravity field, with "down" toward where the engine exhaust is being
directed. For ships that spend most of their travel time accelerating, the
most sensible design would resemble a skyscraper rather than an ocean liner.
    However, when the engines are off, everybody floats. This, combined
with some health problems caused by long term weightlessness, is why
ships and installations which spend long periods in free fall should be
built to spin, like the Babylon 5 space station.
    _B5_ deserves credit for putting a new spin on space drama, but still
falls a little short, in that gravity seems to be Earth-normal regardless
of where in the station people are. In reality, gravity would vary from
zero at the axis, to maximum at the outer hull, with a little Coriolis
twist thrown in to make things interesting. Of course, if you're inside
the space station and you look out a window, the entire universe would
appear to be spinning.
    I am informed that the maximum recommended rate of spin to avoid vertigo
problems is 1 RPM. This means that a space station or ship would need to
be 894 meters in radius to provide a full gravity. At 3 RPM, the previous
recommended rate, a full gravity could be produced with a 99 meter radius.
Thus, depending on the size of the ship, a full gravity may not be available.
When it comes to keeping bones in shape, however, a fraction of a gravity
is still better than none at all.
    The usual practice of having artificial non-spinning gravity perpendicular
to thrust, and more or less constant regardless of what the ship is doing,
seems rather cheesy and suggests a lack of preparation on the writers'
part. It may be that, if artificial gravity generators are invented, ships
will be designed in such a matter. Even so, there *will* be circumstances
in which varying rates and directions of gravity are desired. Zero-G would
be ideal for moving heavy cargo, for example. Also, the gravity should be
just as likely to go out in a fight as any other system, since it's not
being produced by spin. (Speaking of which, if a ship is disabled while in
pitch or yaw, new gravity fields could show up for which the interior wasn't
designed. Smart naval architects will make sure that there are handholds
and ladder rungs everywhere.)
    Differing gravity strengths will have an effect on physical activities
such as running and walking.


Time dilation:
    Speed-induced time distortion has been known about since the 19th Century.
The math is, for the most part, rather simple, and anyone who is the least
bit serious about interstellar travel is going to hear about it. Yet it is
completely absent in every TV show. In fact, in at least one episode of _Star
Trek_, the presence of a person who is physically young but chronologically
old takes everyone by surprise. In an interstellar community, this sort of
thing should be commonplace.
    Even with faster than light travel, time is very likely to be different
for everybody; and while a ship's computer will probably be able to calculate
the time and date based on navigational data, clocks are *always* going to need
adjusting.


Causality:
    Related to the time dilation effect is the issue of "when" events occur.
Again, the notions of "now", "before", and "after" are going to have different
meanings for everybody, which is why the idea of "instantanious" communication
is so ridiculous. A faster-than-light trip is *always* going to appear as
a backward-in-time trip according to *someone's* sense of "now".
    I had high hopes that _Babylon 5_ would do something about the causality
problem when I saw the jump gate in operation. Unfortunately, this show turned
out to be as oblivious as everyone else about it. Ironically, while everyone
else seems ignorant of causality, the makers of the original _Trek_ series
actually used it in three of their plots! Where _Trek_ is lacking is in
explaining why no private FTL ship owners have tried this stunt.
    Causality is a tough nut to crack, and sci-fi writers can perhaps be
forgiven for ignoring it. Niven's _Known Space_ novels don't even address the
issue. However, causality can be dealt with by the introduction of a few
simple rules:

* Establishing a faster-than-light path between two points a distance x
  apart must take time at least equal to x/c.

* Once established, travel through the new route can be arbitrarily fast,
  even "instantanious".

* Changing the reference frame of the jump must needs involve re-establishing
  the route, which again will take time of at least x/c.

* Establishing a jump point becomes more difficult the closer to a previously
  established point and the faster relative to that point this is attempted.

    What you have as a result is a region of explored/colonized space through
which traffic flows quickly, but which can expand only at lightspeed. This
might eventually meet up with another species' similarly expanding bubble,
which can result in anything from a decades-long border war to profitable
trade. Critical to holding causality in check is preventing ships from
instantly and arbitrarily choosing the reference frame of their jumps.
    A variant of this method would be to have the jump routes be naturally
occurring, possibly by means of black holes, as in Haldeman's _Forever War_.
Causality should not be a problem here, since changing the reference frame of
a jump would likely require accelerating one of the black holes, which of
course would have the mass of a large star.


Worlds:
    Most of the action in space shows seems to take place in breathable air,
mostly around room temperature. In reality, hostile atmospheres will certainly
far outnumber breathable ones, and even many oxygen-rich planets will have
atmospheric taint. More of the action should take place on airless worlds if
for no other reason than because they are there.
    Breathable air is not the only valuable resource, though its value alone
would be sufficient reason to put factories elsewhere. Metals and minerals
would be as likely to be on unliveable worlds as on liveable ones. Corrosive
attmospheres might also be useful for certain industrial processes.
    Gravity will vary from near zero on asteroids to above normal on large,
dense planets. People will endure a bit more weight if there's something in
it for them or if the place is otherwise pleasant.


APPENDIX:

Typical distances

                   Distance           Travel time             Radio response
Place             from Earth          at 1 gravity                 time
----------------------------------------------------------------------------
Moon              240,000 miles         3.5 hours               2.6 seconds
Sun               93 million miles      2.85 days              16 min 40 sec
Pluto             3 billion miles       16.2 days                 9 hours

Alpha Centauri    4.3 light years     3.56 years ship            8.6 years
                                      5.93 years global

Sirius               8 LY              4.5 years ship             16 years
                                      9.75 years global

Vega                28 LY             6.65 years ship             56 years
                                      29.9 years global

Rigel              800 LY               13 years ship           1600 years
                                       802 years global

Galactic core    30000 LY               20 years ship          60000 years
                                     30002 years global



Engine performance:

Engine           Oxidizer/   Spec Imp    1G Boost time for mass ratio of
type     Fuel    propellant   (sec)     1.5        2         5          10
------------------------------------------------------------------------------
Solid rocket (typical)          200   1.4 min    2.3 min    5.4 min    7.7 min
Liquid rockets
         Hydrogen Oxygen        460   3.1 min    5.3 min   12.3 min   17.7 min
         Hydrogen Ozone         607   4.1 min    7.0 min   16.3 min   23.3 min
         Hydrides O2 or F2      700   4.7 min    8.1 min   18.8 min   26.9 min
         H+ free radicals      2130  14.4 min   24.6 min   57.1 min   81.7 min
         Metastable atoms      3150   0.4 hr     0.6 hr     1.4 hr     2.0 hr

Fission  U-235    Hydrogen    (avg)
            Solid core          800   5.4 min    9.2 min   21.5 min   30.7 min
            Liquid core        1450   9.8 min   16.8 min   38.9 min   55.6 min
            Gas core           5000   0.6 hr     1.0 hr     2.2 hr     3.2 hr

Ion (*)  Various  Ionizates  200000   0.9 days   1.6 days   3.7 days   5.3 days

Fusion   Hydrogen isotopes  3750000   2.5 wks    4.3 wks   10.0 wks   14.3 wks

Total con   Anti-   Matter
-version   matter (**)        30E+6   4.6 mon    7.9 mon   18.4 mon   26.3 mon


Engine               1G Boost time for mass ratio of
type                   20         50          100         1000
------------------------------------------------------------------------
Solid rocket         10.0 min    13.0 min    15.4 min    23.0 min
Liquid rockets
  Hydrogen Oxygen    23.0 min    30.0 min    35.3 min    53.0 min
  Hydrogen Ozone     30.3 min    39.6 min    46.6 min    69.9 min
  Hydrides O2 or F2  35.0 min    45.6 min    53.7 min    80.6 min
  H+ free radicals   1.8 hr      2.3 hr      2.7 hr      4.1 hr
  Metastable atoms   2.6 hr      3.4 hr      4.0 hr      6.0 hr

Fission
  Solid core         39.9 min    52.2 min    61.4 min    92.1 min
  Liquid core        1.2 hr      1.6 hr      1.9 hr      2.8 hr
  Gas core           4.2 hr      5.4 hr      6.4 hr      9.6 hr

Ion (*)              1.0 wks     1.3 wks     1.5 wks     2.3 wks

Fusion               4.3 mon     5.6 mon     6.6 mon     9.8 mon

Total con
-version             2.8 yrs     3.7 yrs     4.4 yrs     6.6 yrs


* Power is most likely from a nuclear generator. Typical thrust/mass
  ratios are much less than 1 lbf/lb.

** or artificial quantum singularity


References:
Heppenheimer, T.A. _The Man Made Sun: the quest for fusion power_
Boston: Little, Brown c1984.

Mallove, Eugene F.; Matloff, Gregory L. _The Starflight Handbook: a pioneer's
guide to interstellar travel_
New York: Wiley, c1989.

Niven, Larry, ed. _The Man-Kzin Wars_ Volumes 1-5
Baen Publishing Enterprises, New York, NY, 1988-92.

51 responses total.



#1 of 51 by octavius on Wed Jul 26 14:40:20 1995:

Two things:
        The Enterprise does need to refuel once in ahwile (and they even show
it on the old series.)  and it's "Aye, Aye, Captain", Not "Eye, Eye, Captain."
        BTW: The Enterprise uses matter-anti-matter reactions for its fuel, 
and if you're disappointed in the science read Arthur C. Clarke.



#2 of 51 by gregc on Thu Jul 27 08:54:24 1995:

Yes, but *where* does the anit-matter come from?


#3 of 51 by octavius on Thu Jul 27 16:42:26 1995:

        More than lely, Starbases, they never do go into where (or how) they
        get
it into the ship, more importantly.
        However, only 90% of the Science on Star Trek is accurate, not 1000,
        and
even in Arthur C. Clarke's books, he'll suspend the Inverse-Square Law
for dramatic purposes, Asimov is bad when it come to Artificial Intelligence
(i.e., Robots), but it's not something most people will pick up on.


#4 of 51 by cyberpnk on Thu Jul 27 18:32:12 1995:

Was it really necessary to wade through all that? Couldn't those issues have 
been dealt with as they came up?


#5 of 51 by matthew on Sat Jul 29 19:10:19 1995:

A book that deals quite well wiht these issues (and I highly reccomend)
is C J Cherrys Downbelow Station.


#6 of 51 by aruba on Wed Aug 2 04:25:43 1995:

A very nice piece, drew.  Thanks.


#7 of 51 by mneme on Wed Aug 2 05:56:55 1995:

It IS a nice peice, though  it has some theory errors.  To start with, the
thoery theory currently exists for non-time-dialating ftl travel, using strange
matter to compress space in such a way that while a ship never exceed sthe
velocity of light (which is, by current theory, impossible), it traverses the
distance between it's source and destinaton at a fraction of the time it takes
light to traverse the same distance (relative to all three frames of
reference). I have a link to the http site somewhere for the paper, called
theory of a Warp  Drive or someuch.

Some of your other stuff assumes utter reletavistic stuff (like the combat 
section) but it is otherwise good.  (Except that high focus lasers should still
be somewhat effective at medium ranges, remember, they can't see where you are
shooting to dodge).   The rest is perfectly valid (as long as you don't assume
reasonable super-tech, like strange matter for artificial gravity).
.s


#8 of 51 by octavius on Wed Aug 2 17:03:30 1995:

        Technically, there's a thoeory that allows for the "unzzippingg" of
        space,
to allow a ship to travel throubh space but not time
, the problem is zipping space back up.  (I have only heard this mentioned in
passing in converstaions with a friend and cannot verify it.)
        Anyway, you also have to bacnce your sceince fiction with books by
Stephen Hawking, Carl Sagan, and other scientists (or subscribe to magazines
like Sceintiffic American and Discover.)



#9 of 51 by jep on Wed Aug 2 19:23:39 1995:

        Drew didn't address everything possible, but he did outline a few
simple rules which, if followed, could make science fiction TV shows and
movies a lot more believable and interesting.  I thought he did an
excellent job.


#10 of 51 by drew on Fri Aug 4 02:41:57 1995:

Thank you jep. Also thank you Mark and Shawn. #7, I would like a copy of this
file.

It has to be noted that however it is achieved, unzipping space or whatever,
a journey in which a ship reaches a distant star in a few days Earth time is
still going to appear to be a backward-in-time trip to *some* set of
reference frames, whose inhabitants have every right to consider themselves
at rest. It has less to do with mass increase and such than the mathematical
consequences of constant, reference-frame-independent lightspeed.


#11 of 51 by octavius on Fri Aug 4 04:19:42 1995:

  Are the reasons for this routed in Special Relativity?  (Einstein, did, 
after all tell us that all frames of time depend on the observer (if the
observer's speed is less than that of light.)
        I was disappointed that my Physics tecaher didn't go into Relativity,
        and had no questions about black holes on the exam.


#12 of 51 by drew on Sun Aug 6 02:13:20 1995:

"Special Relativity" I believe is the name given to that part of mathematical
physics which deals with high speeds, time dilation, and the like. Yes, this
term would, I guess, encompass the causality issue.

Anyone who proposes a fester-than-light scheme of any kind, IMO, has a couple
of questions to deal with: Is backward time travel possible by this means?
If not, Why not? And If so (in a sci-fi novel), why aren't more people doing
it?


#13 of 51 by octavius on Sun Aug 6 03:47:31 1995:

   I don't believe "unzipping space" requires high velocity, but I'm no expert.


#14 of 51 by mneme on Sun Aug 6 04:38:03 1995:

The warp drive paper I read (which I still can't find my bookmark too...ah,
there it is; "grep Warp */*" to the rescue" http://www.astro.cf.ac.uk
/local/groups/relativity/papers/abstracts/miguel94a.html) presents a solution
to the equasion that doesn't go backwards in time along ANY timestream, but 
it doesn't rule out that possiblity (and certainly the other ftl paper, the one
about wormholes, allows for backwards time travel) in an alternate solution.  
But at least a drive build according to those principles would not have a 
causualty loop.  As far as "why, if you can change time, hasn't anyone" I'd 
resort to Niven's Law (or is it someone else's? Don't remember): if the
timestream can be changed, eventually it WILL be changed so that time travel 
never existed.  Strangely, this is epxressed in virtually every good TT book
I've read, from Asimov to John Crowley.
        Very much liked the rest of the pice, even I I did think it was too 
rigid. Certainly, for a good guide as to how to handle th escience in SF, look
to any good SF writer -- they generally get things more interesting and acruate
than any TV show, even if not perfect.
.s


#15 of 51 by dam on Sun Aug 6 05:44:29 1995:

re#12: FTL.  I'll make a FTL proposal that precludes time travel.

the speed of light is just a speed.  it is perceived as the theoretical 
maximum speed, and all of our formulas are based on that.

so, toss the formulas for this explanaition - I know some of them, 't' 
for 'time' ends up negative for speeds greater than c, and that suggests 
backwards time travel.

I say, if you left earth and flew to the sun in 1 minute, faster than 
light, you would be able to see the events of the past 8 minutes if you 
looked back at the earth.  you would even see your own "ship" there.  
now, you go back.  1 minute.  assuming you could pick out your ship from 
the glare of the sun, you would see yourself arrive at the sun 8 minutes 
later.

you have now traveled faster than the speed of light, but 2 minutes have 
passed, relative to you, relative to the earth, but you have not traveled 
backwards in time.

of course, you do have to toss the theory of relativity in the can for 
this, too, but hey, it's "just a theory" ;)



#16 of 51 by drew on Sun Aug 6 07:56:40 1995:

That doesn't answer the causality issue, since it is supposedly an observed
fact that lightspeed is constant, and the mathematical consequences of such
call for different senses of "before", "after", and "now". On your trip to
the sun, you *have* travelled backwards in time according to the observations
of the crew of a shuttlecraft moving from the Sun to Earth at half lightspeed.
And they are just as correct about their sense of "now" as the observers on
Earth.

Re #14:
    I do not have html, nor the know-how to contact the Web. Could you fetch
for me a copy of this article?


#17 of 51 by dam on Sun Aug 6 17:21:23 1995:

Yes, you are "percieved" and "sensed" to travel backward in time according
to the observations of people at different points of view.
 
my point is, you can travel to a point in space at a speed faster than light,
and travel back to where you started, and do it all in much less time than
it takes light to make the round trip.  you won't, however, find yourself in
1980 when you get back.



#18 of 51 by mneme on Sun Aug 6 18:55:15 1995:

#16:  lynx on grex will give you html.  Easy.  The article is available in TeX
(sorta human-readible, if you ignore the computereese, but you won't see the
encoded  formulae unless you explode it) and Postscript (get everything, but
only if  can print postscript, since you can't do formulaae in plaintext.


#19 of 51 by drew on Tue Aug 8 02:12:29 1995:

Re #17:
    Why not?? The observations of the various people are every bit as valid
as the observations of people on the ground. If you can travel backward in
time according to the reference frame of the shuttle, it stands to reason that
you should be able to select your reference frame of jump such that you have
positive trip time t < x/c according to the shuttle, and negative t according
to the ground crew. Nobody is special, unless someone can show why.

Re #18:
    I suspect I will not be able to access lynx. I will try upon exiting this
conference.


#20 of 51 by drew on Tue Aug 8 02:19:10 1995:

lynx activates, but I believe I need Member status to get anywhere other than
grex. I might be able to have some success with the www account on msu-gopher.


#21 of 51 by robh on Tue Aug 8 02:20:25 1995:

Yes, you do need to be a member to access Web documents on
other sites.  You can look at local files with Lynx, though.

The Web site at gopher.msu.edu is a decent one, too.


#22 of 51 by octavius on Tue Aug 8 04:27:34 1995:

   Or Telnet to WWW.CORNELL.EDU.  Does anyone know anyplace that will allow me
   to anonymous FTP so I could get some files on the subject?  
        Bucknell University is too cheap to let the public do it.


#23 of 51 by bru on Tue Aug 8 14:23:40 1995:

Babylon 5 circumvents the need for FTL by using Jumpgates and Jumpoints.



#24 of 51 by octavius on Tue Aug 8 18:14:14 1995:

        I think those ships are travelling faster than light, its just that
their not doing it on theri won.  (I also believe they did this in Buck Rogers
in the 24th Century.)


#25 of 51 by drew on Tue Aug 8 21:20:18 1995:

Yes, they did something like that in (Beedeebeedeebeedee) Buck.

The jump gates are a good start, but they need more limitations. To wit, it
should take at least 8 years to set up a jump route between Earth and Sirius,
although once formed, it could be traversed in days. And ships that form their
own jump points, likewise, should end up travelling at just under lightspeed.

This would make a good reason for _Explorer_ class survey ships to still use
jump gates when available, and a decent reason why they are seldom
encountered: They are travelling at lightspeed out on the rim, where jump
gates have not been set up yet.


#26 of 51 by bru on Wed Aug 9 17:04:28 1995:

They create their own jumppoints utilizing their jump engines.  Only large
ships are capable of doing this.  Smaller ships use the gates they build 
as they find places of interest.  smaller ships do not have jump engines, as
use of gates is far "cheaper" than use of the engines.  This is why the 
larger ships use the gates when they can, to save the wear and tear on the
jump engines.  Not because it is faster.


#27 of 51 by octavius on Mon Aug 14 04:15:36 1995:

  Is there any book on the theories behind the form of space travel used in
  Science Fiction series.  It seems to me that this could save a lot of
  confusion.


#28 of 51 by drew on Tue Aug 15 04:19:58 1995:

I'm not sure it's what you mean, but I do recommend _The Starflight Handbook_
listed in the references at the end of resp. #0.


#29 of 51 by octavius on Tue Aug 15 04:50:54 1995:

  Who wrotte it?



#30 of 51 by drew on Wed Aug 16 02:41:05 1995:

Mallov, Eugene F,; Matloff, Gregory L. _The Starflight Handbook: a pioneer's
guide to interstellar travel_
New York: Wiley, c1989.


#31 of 51 by drew on Mon Oct 2 01:55:50 1995:

Okay, I've tried www.cornell.edu. Telnet gives me a login: prompt, for which
I know no logins. ftp works (!) and accepts anonymous login. There are a grand
total of about 5 directories in root: bin, dev, etc, usr, and pub. The only
one I can read is /pub, which contains two files: student_dir and staff_dir
or something to that effect, both humungous (megabyte-sized). Where do I go
from here?

As for the www site, I still don't have the necessary software set up to go
get what I'm after (unzipping space FTL theory), though I have been given a
shitload of 3.5" floppies, some containing internet stuff.


#32 of 51 by mneme on Tue Oct 3 02:10:34 1995:

Telnet should work nicely, witha login of "www" or "lynx" or some such (for
cornell).  On the other hand, I am finally putting ~mneme/ftl/fig1.ps 
and ~mneme/ftl/miguel94a.ps for postscript printers, and miguel94a.tex (for TeX
the document processing system (avaiable free through anonymous ftp), which is
also the most human-readable of the set) up on the system, and making them 
world readable even as I write this.


#33 of 51 by drew on Wed Oct 4 11:39:15 1995:

I ftp'd the files last night. Keep 'em around about a day or so, just in case
something didn't take. Now to find a postscript viewer...


#34 of 51 by octavius on Wed Oct 4 13:52:46 1995:

   You should login in as www if you want to use the web.



#35 of 51 by drew on Thu Oct 5 16:27:42 1995:

    I got the files over to work (finally!) wherein it was a simple matter
to print them out on one of the PostScript printers. I have a few comments
and questions about this space warp idea; however, it occurs to me that
discussion of FTL travel deserves a separate item, which I shall enter
presently.

    New space shows are bound to come out eventually, of course, and the
latest is _Space: Above and Beyond_. The colony transport ship in the first
episode looked promising. However, with the fighter craft, carriers, and
Mars shuttle, they blew it. Ships pointed the wrong way on aproach; non-
spinning gravity erpendicular to thrust; fighter-craft maneuvers wherein the
forces which changed the course of a craft seemed to come from the wings;
asteroid belt impossibly dense; craft in combat too close together and moving
too slowly for space combat.

    However, _Space/AB_ has hit upon a good solution to the causality issue
with their introduction of wormholes - which are naturally occuring and
which open and close in uncontrollable though predictable patterns. Since
there is no control over the wormholes, neither would there be control over
the reference frame of a wormhole jump.

    This aspect of interstellar travel will certainly have an effect on
interstellar warfare. Since an attacking fleet must use the wormholes, it
should be a simple matter to find the likely entry points to a system, and
station a couple of cruisers at each one to pick off the enemy ships as they
come through. A successful attack is going to require finding a wormhole
opening far enough away from the target to be undefended, then proceed from
there in normal space.

    (I was hoping to see a wormhole jump in last Sunday's episode; but I
missed the first few minutes.)


#36 of 51 by octavius on Sat Oct 7 01:00:56 1995:

        Just a minor flaw with the wormholes, they are naturally occuring,
but nothing bigger than a subatomic particle can fit through them.  


#37 of 51 by torbick on Sun Oct 8 06:06:47 1995:

The system of interstellar (and even fast interplantary) travel was in a game.
In GDW's Traveller 2300 and 2300 AD ships used a drive called "stutterwarp"
Stutterwarp used the tunneling phenomenon know to occur in subatomic particles
applied to larger objects.  A ship driven by stutterwarp "tunnels" a few 
hundred meters millions of times a second. Rather neatly circumventing 
distance.  The rest of the details are in the game.  It made sense to me. 
Stutterwarps becomes less effective the closer you are to a gravity well.
On a planetary surface it is useless.  No artifical gravity, No forcefields,
no transporters.  Too bad the game didn't do better.


#38 of 51 by mneme on Mon Oct 9 21:40:34 1995:

#36 I believe soemone's done the math for ship-size wormholes.  They'd require
the ability to play with strange matter (read: build tiny black holes ala
_Earth_) but what the hell?


#39 of 51 by octavius on Sun Oct 15 02:46:56 1995:

   General Relativity does not allow a ship to pass through a black
hole (or anything else for that matter) without being torn to a million
(or more) pieces.  The neat thing is, you'll be stretched and torn
apart at about the same time at the speed of light.)
        My understanding of dark matter (and I am no expert) is that 
Newton's model of the universe requires it (because the Universe is
always uniform) and Einstein's does not.
        Anyway, Stephen Hawking goes into Hyperspace a little in _A Brief
History of Time_.  He says that Hyperspace isn't actually exceeding
light speed.  Instead, you are cutting through a dimension as a shortcut.
(I hope I've got this right.) It would be something like travelling
to China by airplane (making an arc), oppposed to digging through the Earth.
The distancce would be less if you dug straight through to China. (The shortt-
est distance between two poinst is a straight line.)
        Anyway, something I'd like to see some science fiction author
take up is the idea of what happens (correctly) to orbiting bodies around
black holes.  They do emit radiation, and since the gravity outside the
gravity welll is the same of that as the original body, they should
still be there.


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