Physics Question: What is an appropriate FTL drive for SF-RPGs?
John H Kim
> To all of you physics people out there:
OK - I'm in experimental particle physics, so I am not really an
expert on all this wierd general relativity and tachyon stuff. However,
I am sufficiently conceited that I think my opinions are worth
hearing @-).
>
> I am designing a Sci-Fi RPG setting that is interstellar in
>nature. Thus, I need a faster-than-light drive.
...
> But that doesn't mean that I don't want something that
>is "quasi-semi-sortof" believable. So, I am curious as to
>what type of FTL drive sits best with you guys...the types
>that are popularized by fiction, that I can think of, are:
>
> Folding Space (Dune)
> Warp Drive (Star Trek)
> Hyperspace (Star Wars and countless novels)
> Tachyons (just a neat idea)
> Shutterwarp (from 2300AD RPG)
> Stargates (Babylon-5)
>
>Anyone have any comments on the above?
Well, by far the easiest to reconcile with present physics is
the `stargate' idea. Essentially, FTL travel is not possible. Rather,
the geometry of the uuniverse is much stranger than we thought, and it
turns out that a point in space in our solar system is actually right
next to a point in space in another solar system.
There are specific points which a given stargate will connect
to. Stargates are a natural phenomena - technology may facilitate travel
through a stargate, but it cannot create a stargate where none existed
before.
Any FTL scheme where you are free to move where you want to
go (i.e. warp drives, stutterwarp, hyperspace, etc.) will require major
revisions to relativity in order to avoid time travel and other paradoxes.
OTOH, this is not neccessarily a bad thing since most people don't
understand relativity anyway.
The stargate theory requires major changes to our ideas about
how our universe is shaped (cosmology), but it does not neccessarily
require change to our more fundamental ideas of how things work
(Relativity, Field Theory,...).
------------------------------------------------------------------------------
John Kim | "Whatever else is true, you - trust your little finger.
jh...@columbia.edu | Just a single little finger can... change the world."
Columbia University | - Stephen Sondheim, _Assassins_
Dave Van Domelen
Hi. AMO Experimental here, but only cuz I didn't have the grades to make
it into the General Relativity group. }->
>
> Folding Space (Dune)
> Warp Drive (Star Trek)
> Hyperspace (Star Wars and countless novels)
> Tachyons (just a neat idea)
> Shutterwarp (from 2300AD RPG)
> Stargates (Babylon-5)
>
> Anyone have any comments on the above? I'm not interested in any
>"FTL is not possible" comments....I know that. But I have decided
>to include FTL in my game, and I want your opinions on which
>method you like the best...
Well, first off, some of those can be grouped. Warp drive and folding
space are the same thing: locally twist spacetime so that your trip is shorter.
Stargates are similar, but require static bases (either because a ship couldn't
hold the generators or because natural anomolies are used). Hyperspace
postulates that you can leave reality and enter one with physical laws more to
your liking. No clue about Shutterwarp. Tachyons are a classic case of "A
little knowledge is a dangerous thing," or at least an embarrassing thing.
Yeah, Tachyons go faster than light, but they can't go slower than it.
Tachyons are pretty stupid as an FTL method, IMO, since it tries to keep 'hard'
science while ignoring science altogether. }->
Anyway, the type of stardrive you choose depends on A: how much of the
physical law you want to change (since FTL is impossible for various very good
reasons) and B: how far you're willing to push the change you've made.
One common change is to simply change the causal type of your universe.
Instead of the speed of light being due to the nature of spacetime, have it
being due to the Aether, which lets you keep the speed of light constant while
erasing the problems of FTL. In that case, you just need to keep accelerating
to exceed lightspeed.
Another change is to strike most of General Relativity, specifically the
fact that gravitational mass and inertial mass are coupled. Aside from
allowing the standard antigravity drives in SF, this can let you change
spacetime without introducing matter or removing it. One neat effect is that
with a powerful enough energy source, you can fold space, although you have to
ignore the tidal stresses this would put on a ship. Another trick is to grab
your local bit of spacetime and propel the whole area along a gravity wave.
Now, most physicists assume the speed of gravity waves (if they exist) would be
the same as lightspeed. But there's no real reason to assume that in SF. You
can say that the gravity wave can go some multiple of light speed, or maybe
even be linked to how much power you put into it. And since the entire space
is carried with, you're safe inside...and anything trying to cross your
interface would be destroyed or reflected, making for a natural defense screen.
Of course, ships would have to be very careful about being near shipping lanes
while not under warp, since they could be torn apart by an 'eddie' in spacetime
as a ship passes. Also, this interface would block communication unless the
interface itself is vibrated to send out gravity pulses for communications
purposes...or for offensive purposes. You can see I've given this alot of
thought. }-> Every major part of the Enterprise, for example, could be
explained in this way: warp shields, warp drive, keep the local curvature
nearby sufficient to create artificial gravity, hyperlight communications by
gravity wave, tight beams of localized warping for phasers, black hole bombs
(artifical black holes are very short-lived) as Photon Torps, etc. Neat, huh?
You can even go farther and decouple matter mass from inertial mass, like
the Bergenholm drives in Lensman. Add that to an Aetherous universe, and your
top speed is limited only by the friction due to local dust....
Dave Van Domelen, having fun warping reality....
than...@interaccess.com
>: [...] I need a faster-than-light drive. [...]
>: Folding Space (Dune)
>: Warp Drive (Star Trek)
>: Hyperspace (Star Wars and countless novels)
>: Tachyons (just a neat idea)
>: Shutterwarp (from 2300AD RPG)
>: Stargates (Babylon-5)
>
The Smoot Drive was introduced in the Marvel Anthology Open Space, a
series ahead of its time. It postulated a staggeringly easy to
build transporter called the Smoot with two little problems:
1) It could not be used outside of a vaccuum.
2) It could only teleport 1 Smoot, which is roughly equivalent
to the radius of a Hydrogen atom.
Wow. 1 atomic radius. Big deal, right? Wrong.
Say you could cycle the system so that it repeated itself 100 times
every nanosecond. That would mean that in one second, the smoot
could teleport itself 1x10^11 ARadii. Put simply, it would give
the craft the illusion of motion, but...get this NO INERTIA! So
basically, screw Einstein and the silly laws of relativity. With
a sophisticated enough computer and navigation system, you could
get a lot more out of the Smoot than 100 every nanosecond.
Long live the Smoot.
--
than...@interaccess.com / "Want to go to Toner's after this?
DeathUrge, Master of Unknown \ I always like it."
Time and Space. / - John Constantine, _Hellblazer_
"It's a Zen thing. You wouldn't understand."
Guy Robinson
: I am designing a Sci-Fi RPG setting that is interstellar in
: nature. Thus, I need a faster-than-light drive.
: Now I've had basic physics, so I know all about relativity
: and the speed of light as an absolute speed maximum (or at
: least I think I know). However, this is a fictional game, so
: I'm going to ignore nature's laws and have FTL travel.
: But that doesn't mean that I don't want something that
: is "quasi-semi-sortof" believable. So, I am curious as to
: what type of FTL drive sits best with you guys...the types
: that are popularized by fiction, that I can think of, are:
Here are my favorites:
The Improbabilty Drive
By increasing improbability the vessel has a probably chance of
spontaneously arriving at it's destination as this is a very
improbable affair.
Source: Douglas Admans
The Bad News Drive:
Nothing travels faster than Bad News but when you arrive no-one
want to talk to you ...
Source: Douglas Adams
Stellar Lay-Lines
Between the starts there are a kind of stella lay lines through
which FTL travel is possible. This conveniently allows people
to travel from point of interest to other points of interest
and puts some parts of the Universe out of access.
Source: Mote in Gods Eye, SF Book.
: Thanks...
: +---------------------------------+-----------------------------------+
: | Andrew Akins | Iowa State University |
: | Applications Programmer | Center for Agricultural and |
: | ara...@iastate.edu | Rural Development |
: +---------------------------------+-----------------------------------+
--
Guy Robinson guy....@rx.xerox.com
[implied disclaimer]
The real meaning of Christmas is a Mid-Winter feast.
Ron
>to a lot of paradoxes, but thats FTL. Quantum tunneling has been observed, and
>perhaps quantum gravity or a GUT can influence it. Creating some kind of
>field to make everything jump at the same time in the same direction is a bit
>harder to swallow, but it might be possible.
i've heard that quantum mechanics conflicts with relativity in some
pretty major ways. relativity is for large scale, but once taken
to a small scale it breaks down ...
(i'm not an expert on any of this. take this post as what it is:
an attempt to get some more knowledgeable person to explain where
quantum mechanics and relativity disagree. if it is over
quantum tunneling then perhaps this could be used as FTL)
- ron
--
(ron) rm9...@meibm10.cen.uiuc.edu
Neal Sofge
That's effectively the same as the 2300 AD Stutterwarp, bub. And I think it
worth noting that 2300 was out four years before Open Space hit the comic
store shelves.
-------------------------------------------------------------------------
Neal Sofge, Geek-at-large (Neal_...@rand.org)
Going slow in the left-hand lane on the Information Superhighway!
These are my opinions, I don't speak for RAND. Yet.
David Summers
less numerous and less blatant problems with current theories and
since modern theories, by necessity, "only" consider the universe
then a process that might be opperating outside the inverse can
opperate differently (as a more general case).
--
________________________
(Disclaimer: If NASA had any postion on any of this do you think they
would have ME give it?)
David Summers - DPSu...@Ames.ARC.NASA.Gov
Tracy Ratcliff
Neal Sofge <Neal_...@rand.org> wrote:
>>None of the above. Use the legendary Smoot Drive.
>
>That's effectively the same as the 2300 AD Stutterwarp, bub. And I think it
>worth noting that 2300 was out four years before Open Space hit the comic
>store shelves.
>
Polesotechnic League stories starting in the late fifties.
Rockerboy
: To all of you physics people out there:
: I am designing a Sci-Fi RPG setting that is interstellar in
: nature. Thus, I need a faster-than-light drive.
: Folding Space (Dune)
: Warp Drive (Star Trek)
: Hyperspace (Star Wars and countless novels)
: Tachyons (just a neat idea)
: Shutterwarp (from 2300AD RPG)
: Stargates (Babylon-5)
Depending on how accessable and safe you want FTL travel to be, you might
consider the method put forth in Warhammer 40K. It presupposes an
alternate reality called the Warp, and ships travel through this medium
at much increased speeds (with respect to normal space.) The method is
dangerous, however, as the Warp is inhabited by monstrous things. It
also requires powerful psychics (astropaths) to navigate through the
Warp. FTL communications are done via psychers, as psychic communication
travels via the Warp. Of course, psychers sometimes get posessed by
demons, etc., and this can be very nasty indeed. The forces in the warp
can mess things up terribly, so much so that the Emperium is willing to
wipe out entire planets of people rather than risk things getting out of
hand. (So the imperium claims, anyway. If you ask me, the Emperor is
long dead.)
--
'Sometimes what you have to say is going to get right in the faces
of the powerful people who really run this world. But you don't
care....It's your place to challenge authority...'
roc...@netcom.com (Rockerboy)
Ross Smith
>
> I am designing a Sci-Fi RPG setting that is interstellar in
>nature. Thus, I need a faster-than-light drive.
>and the speed of light as an absolute speed maximum (or at
>least I think I know). However, this is a fictional game, so
>I'm going to ignore nature's laws and have FTL travel.
> But that doesn't mean that I don't want something that
>is "quasi-semi-sortof" believable. So, I am curious as to
>what type of FTL drive sits best with you guys...
Some kind of "star gate" or "wormhole" system is probably the most
plausible in terms of present-day physics. I can think of at least three
variations on this theme...
(1) Starships carry their own wormhole generators. When you want to make
an interstellar jump, your generator opens a wormhole to your destination
point, the ship passes through it, and then the wormhole is allowed to
collapse again.
Comments: Generating a wormhole would take an enormous amount of energy;
this would probably mean a fairly large minimum practical size for a
wormhole-capable ship (thousands or millions of tonnes), and it would
probably have to refuel before doing it again. There's all sorts of room
for interesting errors in "aiming" the wormhole; if you're not careful you
could find you've come out on the other side of the Galaxy (or the
universe), or a million years in the past or future, or even in another
universe. More than one ship could use the same wormhole; it might be
common practice for one large wormhole-capable ship to open a passage for a
whole fleet of smaller ships.
(2) Wormhole generators are too big to carry on ships; inhabited systems
have them mounted permanently in space stations. When you want to travel
from Alpha Centauri to Tau Ceti, you pay the operators at one of the Alpha
Centauri stations to open a wormhole for you. Frequently travelled routes
would probably have wormholes open permanently.
Comments: Obviously this limits exploration somewhat. You can visit
uninhabited systems, but you'll have to make prior arrangements with the
operators in the system you left to re-open the wormhole at a specified
time so you can get back. You can't travel between two uninhabited systems
at all. The size of a wormhole generator would place an upper limit on the
size of the ships that can use it. If the biggest generator in the Alpha
Centauri system can only handle 10,000 tonne ships, while Tau Ceti can
manage 50,000 tonne ships, and your 20,000 tonne freighter is stuck at
Alpha Centauri, you'll have to send another ship to Tau Ceti to tell them
to open a wormhole for you.
(3) Wormholes are permanent. A network of wormholes, linking most of the
stars in the Galaxy, was set up millions of years ago by an unknown and
long extinct civilisation. Nobody knows how to make more of them.
Fortunately, nobody knows how to make less of them either.
Comments: Star systems with several wormholes would become the centres of
interstellar civilisation (just as towns built where rivers meet became the
centres of ancient civilisation), while those with only one wormhole would
be backwaters, colonised by those who want to get away from civilisation.
The structure of interstellar civilisation would be highly dependent on the
typical number of wormholes per system; a galaxy where a few stars with
many wormholes were connected by "chains" of stars with two each would be
very different to one where most stars have three or more wormholes. If a
route between two important systems happened to pass through a system
having intelligent but low-tech natives, they would probably undergo much
the same sort of high-speed development that befell the natives of many
Pacific islands during World War II. Probably all the wormholes are the
same size, which places an absolute upper limit on the size of interstellar
ships.
If you want to be a bit more off the wall, here are a few more suggestions,
in approximate order of increasing faroutness...
(4) "The Currents of Space": There are "eddy currents" in the structure of
spacetime (or some similar scientific doubletalk); occasionally these
become sufficiently intense that it becomes possible to open a wormhole.
You can't "aim" the wormhole; you have to pick your place and time
carefully, analysing the currents of spacetime to determine where you can
come out. The patterns can be predicted in advance to a limited extent; if
you want to reach a specific destination, you have to analyse the currents
in the star system you're in, and work out where and when a suitable
"window" allows a wormhole to be opened. This is easier in a civilised
system, with "weather stations" scattered all over it, than in a newly
explored system where you have to do everything from one ship. If you're
running away from something nasty and just want to get anywhere at all in a
hurry, you can probably find a window fairly quickly, but it's anybody's
guess where you're going to end up -- or whether the window will stay open
long enough for someone to follow you.
There's an element of luck involved; you may find that a window to Tau Ceti
will be available in a few hours, or you might have to wait weeks. On the
other hand, a window to Epsilon Eridani might be available much sooner, and
you have to decide whether to wait for your direct connection, or go to
Epsilon Eridani on the chance that a window from there to Tau Ceti might be
available sooner. Obviously any kind of scheduled service is out of the
question.
The scale of interstellar society will depend on the typical range of
wormholes. If most wormholes from any given system reach only a few
light-years away, civilisations will be small and tightly clustered; if
they typically reach hundreds or thousands of light-years, much of the
Galaxy can be explored.
(5) "The Golden Eggs": During the 22nd century, prospectors in the Oort
Cloud found some peculiar objects on some of the larger cometary bodies.
They are spheres made of some unknown golden metal, apparently containing
particles of "strange matter" (if you're not familiar with this interesting
stuff, see the January '94 issue of _Scientific American_); they vary only
slightly in size (20-30 centimetres), with a mass of several tonnes.
Researchers discovered that the "Eggs" were capable of converting a
powerful electromagnetic pulse into a gravitational pulse that could, if
properly focused, open a wormhole in spacetime. From here, things proceed
pretty much as in scenario (1) above.
Nobody knows where the "Golden Eggs" come from. They're found scattered
through cometary haloes all over the Galaxy; when we met aliens, we
discovered that they had been using the Eggs for millennia, and they didn't
know where they came from either. One theory has it that they were formed
in the Big Bang (but nobody knows how). Another suggests that they
literally are eggs, laid by some kind of interstellar animal (which nobody
has ever seen). Or perhaps they were made by some ancient civilisation,
and scattered around the Galaxy for some unknown reason.
Prospectors make their fortunes, or get very poor and very bored, searching
cometary haloes for Eggs. They're distributed unevenly; you can search a
hundred comets and find nothing, then come across one with thousands of
Eggs embedded in it. Perhaps they become the basis of interstellar
commerce -- the "Golden Egg Standard".
(6) "The Star Whales": Creatures live in interstellar space; they evolved
billions of years ago on a world that lost its atmosphere, or perhaps in
the upper layers of a gas giant planet. Eventually they adapted to space,
and a few species evolved the ability to generate their own wormholes and
spread across the Galaxy. Some of these creatures are large enough to
carry spaceships along with them; a Star Whale fifty metres long, with a
mass of five hundred tonnes, can open a wormhole big enough for a ship of
twice its length and ten times its mass.
They're not highly intelligent; perhaps as smart as dogs. You can't force
them to do anything; if you mistreat a Star Whale, it simply vanishes. But
they can be persuaded, or trained, to cooperate with humans. They can be
rewarded with whatever it is they eat (liquid hydrogen? plutonium?
strange matter?). Fully trained Star Whales, suitable for carrying a large
liner or warship, are very expensive; owners of small prospecting ships or
tramp freighters would buy a young calf from a reputable breeder (or, if
you're really cheap, a disreputable one) and train it themselves. Just
think of all the things a puppy can do wrong while it's learning, and scale
it up to the size of a small starship...
Anyone who wants to use any of these ideas is welcome to them.
--
Ross Smith (Wanganui, New Zealand) ... al...@acheron.amigans.gen.nz
GCS/S d? p c++++ !l u-- e- m---(*) s+/++ n--- h+ f g+ w+ t-/+ r+ y?
Keeper of the FAQ for rec.aviation.military
"This calls for a very special blend of psychology and extreme violence." (Vyv)
Paul Kinsler
: My favourite is the 2300AD Stutterwarp. The idea is that it is possible to
: somehow make large physical system perform quantum tunneling a short distance.
: [...]
: The drive is not that bad from a scientific standpoint. Of course it will lead
: to a lot of paradoxes, but thats FTL. Quantum tunneling has been observed, and
: perhaps quantum gravity or a GUT can influence it. Creating some kind of
: field to make everything jump at the same time in the same direction is a bit
: harder to swallow, but it might be possible.
Quantum tunneling doesn't "go" faster than light speed.
I my campaign i have replaced quantum tunneling with short hyperspace hops.
--
------------------------------+soluble fish+------------------------------
"You people, you do not see the grandeur in the wind and stone and stars,
in the blood and fire and iron - but paint only the flowers."
par...@vaxkab.e.kth.se
I've got an idea.
First Einstein was wrong you can go faster than the speed of light.
The increse of speed is linear following good old Newton. But physics
still works as we know it. How is this possible?
I'll try to explain my idea by using a analogy.
The speed you can accelerate a gas or plasma to is limited by the speed
of sound. The only way to increase the flow to supersonic speeds is to
let it pass through a Laval nozzle (I think that's what it's called).
The flow doesn't need to pass through a physical nozzle but must be
affected by forces which create the same percived structure for the
gasflow. As an example there was suprise when it was found that the solar
wind was travelling at supersonic speeds. It was later shown that the
fieldlines from the sun acted as laval nozzle on the solar wind. My idea is
that
a) there exists a FTL nozzle which is necessary to pass through to achieve
superlight speed. If one doesn't pass through a nozzle the relativity
is in effect. The FTL nozzle could be created by the forces of diffrent
planets working in unison. In other words there would be stargates which
had to be used to achieve superlight speed.
or
b) You could accelerate a plane to supersonic speeds without a Lavalnozzle
so maybe you could accelerate space ships to superlight speeds without
a FTL nozzle. But small particles like electrons,photons or loose
structures like gas and plasmas would have to pass through a FTL nozzle.
As far as I know one has yet to accelerate any physical object of human
size or larger to relativistic speeds so it could work with today science.
Well almost.
-The Troll
---------------------------------------------------------------------
Truls Parsson / The secret of success is sincerity, once
par...@vaxkab.e.kth.se / you can fake that, you've got it made
---------------------------/-----------------------------------------
Disclaimer: / If at first you don't succed...
I don't use disclaimers / Destroy all evidence that you've tried.
---------------------------------------------------------------------
par...@vaxkab.e.kth.se
In my earlier article I proposed an idea for FTL travel. However I forgot
to mention a minor problem with the ideas of accelerating a ship to
superlight speeds. If you start with no velocity and accelerate your ship
with 7G it would take (if my memory serves me right) round about 80 days
to reach 90% of light speed. Not that you would be able to live with a
constant acceleration of 7G for a longer time period. Does anybody have an
idea of how to negate the effects of high acceleration.
Joseph Dzikiewicz
...Paul <cle...@magritte.its.rpi.edu> wrote:
>No, no, no... Use the Smut Drive...
>
>You get yourself some hamsters, right, and some hamster porn mags, right.
>
>You put the hamsters on little wheels, okay, and make sure they haven't
>had sex in several years (which is a long time, in hamster years). Then,
>you show them the magazine, and, being that they're hamsters, and very
>horny, and very stupid hamsters at that, they'll start running towards
>the pictures. This makes the wheel go. The hamsters will accelerate
>when they find out they're not making progress (after all, they'ver VERY
>stupid, and VERY horny). Eventually, the wheels will achieve the speed
>of light in rotational speed, the hamsters will explode, releasing a
>massive amount of energy, which can be used for thrust. This thrust is
>enough to propel any spaceship halfway across the universe in a matter
>of seconds. After all, sexually depraved, horny hamsters pent up a LOT
>of energy... :)
This works even better with undergraduates.
Dave Sherohman
>constant acceleration of 7G for a longer time period. Does anybody have an
>idea of how to negate the effects of high acceleration.
The Space Master Way: Use a RIF (Relative Inertial Field) generator. I think
they handwave it as 'suspending certain laws of physics' so as to negate both
the ship's inertia (allowing ungodly accelerations (ie, 0 to FTL in 60
seconds) without squashing people like bugs or tearing the drives off the
hull) and relativistic effects.
The Explainable Way: Assuming you have gravitic manipulation technology,
just set up an artificial gravity of -6G, giving a net 1G. If the grav
fields can be used upon the ship itself as well as within it, you can also
use it to reduce stresses upon the hull, thereby sidestepping many engineering
problems. (Note that it is recommended that the grav generators be _at_least_
triply redundant... :)
Bill Hay
" writes:
> In my earlier article I proposed an idea for FTL travel. However I forgot
> to mention a minor problem with the ideas of accelerating a ship to
> superlight speeds. If you start with no velocity and accelerate your ship
> with 7G it would take (if my memory serves me right) round about 80 days
> to reach 90% of light speed. Not that you would be able to live with a
> constant acceleration of 7G for a longer time period. Does anybody have an
> idea of how to negate the effects of high acceleration.
>
Well filling your bodies cavities with liquid is supposed to help with
acceleration. You then have to figure a way to breathe or avoid the need to
do so.
--
Bill Hay
Ron
>> to mention a minor problem with the ideas of accelerating a ship to
>> superlight speeds. If you start with no velocity and accelerate your ship
>> with 7G it would take (if my memory serves me right) round about 80 days
>> to reach 90% of light speed. Not that you would be able to live with a
>> constant acceleration of 7G for a longer time period. Does anybody have an
>> idea of how to negate the effects of high acceleration.
>>
>Well filling your bodies cavities with liquid is supposed to help with
>acceleration. You then have to figure a way to breathe or avoid the need to
>do so.
in ABYSS, the movie, they had liquid gunk you could breathe. in one of
Asimov's technologies to watch guides he mentioned fluorocarbon-liquid,
which has an oxygen substitute.
in SPHERE, by Creighton (sp?), that author had a pilot couch/seat which
surrounds you with sacs of water ... or something to that effect.
Steven Sharp
>
>Quantum tunneling doesn't "go" faster than light speed.
Apparently a recent experiment seems to indicate that it is instantaneous.
(This is a vague recollection of a posting in sci.physics.)
I don't know what frame of reference it is supposed to be instantaneous in,
perhaps the frame of the particle or the frame of the potential barrier.
At any rate, if this is true, in some frames it would take positive time
and in others it would take negative time. The latter case is probably
equivalent to a virtual anti-particle tunneling the opposite direction in
positive time and destroying the original particle. Since you can't control
the tunneling, it can't be used for FTL communication or travel anyway.
Steven Sharp
>I rather like the idea of having a very long elliptical
>ship. The recipe goes thus: Accelerate for ages until your
>length goes way down and your mass goes way up. At some
>point you will become a black hole from the perspective
>of the rest of the universe. Then wing it!
"Relativistic mass" does not behave the same way gravitationally as normal
mass and cannot produce an event horizon. Remember that "relativistic mass"
depends on the frame of reference that the object is being observed from.
This kind of difference from real mass is why physicists have moved away
from using the term.
douglas craig holland
>ara...@iastate.edu (Andrew R. Akins) writes:
>> I am designing a Sci-Fi RPG setting that is interstellar in
>> Anyone have any comments on the above? I'm not interested in any
>>"FTL is not possible" comments....I know that. But I have decided
>>to include FTL in my game, and I want your opinions on which
>>method you like the best...
>
>right out the window, of course, but as another poster pointed out,
>you don't lose much anyway since most people don't have a great idea
>how relativity works in the first place. Some of this is obvious
>waffle, but you need some waffle when describing something outside the
>(known) laws of physics. :-)
>
>You mentioned 'folding space' from the Dune series... that sounds sort
>of like this, but I'm not familiar with Dune and I invented this stuff
>myself. Hopefully there's at least _one_ original idea in here!
>
>This is a direct extract from my campaign background file, with some
>bonus info about the availability of FTL radio communication and the
>operation of ship sensors (I hate the Star Trek idea that you can 'scan'
>another ship and tell what everyone on board is doing...); enjoy!
>=====
>
>The skew-drive skews the normal set of spatial dimensions into an
>orthogonal set, so that normal propulsion methods move a ship along
>at sub-light speeds through the orthogonal ``skew-space''. When the
>dimension skewing is then relaxed, the ship is found many light years
>from its original position in real space. Only theoretical physicists
>and skew-drive engineers really know how it all works. This travel method
>is quite safe, so long as you have enough computing power on board to
>calculate various parameters correctly.
>
>The skew-drive is characterised by trips taking a finite amount of time.
>While in the dimension-skewed state, interaction with real space is
>possible, but not very easily. Such interaction would involve a part of
>the ship relaxing into real space, which naturally puts mechanical
>stresses on its construction. Course changes can be made while in the
>skewed state, but navigation must be done either by dead reckoning or by
>letting some of the ship's sensors relax into real space. The dimension
>skewing can be performed anywhere in real space, and skew-drive ships
>routinely leave planetside docks by skewing while on the landing pad.
>Returning a ship to real space is usually done some distance from any
>large body, since trying to do this safely on a landing pad would
>require enormous amounts of luck and courage.
>
>Radio communication is restricted to the speed of light. The fastest way to
>get information anywhere outside one's own stellar system is to send a ship
>with a messenger. Ship sensors are usually restricted to detecting
>electromagnetic and gravitic radiation, so very little can be learned about
>another ship when encountered in space unless it either transmits or leaks
>useful information. It is possible to scan with a wide-beam x-ray laser and
>detect internal ship structures, but this is usually seen as a hostile
>action, as the x-rays are dangerous to most organisms.
>
>- David Mar. m...@physics.su.oz.au
>Astrophysics Department, University of Sydney NSW 2006, Australia.
Here's an idea I came up with when I read this. Radio communication is
restricted to the speed of light, and there is no "subspace" to facilitate
FTL radios. However, what if you can permanently put a telephone cable
into skew. You could have telecommunications lines only a few kilometers
long, but would link Earth with Alpha-Centauri. This could link up all
of the civilized worlds in the galaxy, but would leave ships and explorers
on their own.
Doug Holland
--
| Doug Holland | Proud member of:
| hol...@beethoven.cs.colostate.edu | Mathematicians Against Drunk Deriving
| Finger for PGP 2.2 key |
Spam El - Last Spam of Krypton
writes:
[stuff deleted]
>in ABYSS, the movie, they had liquid gunk you could breathe. in one of
>Asimov's technologies to watch guides he mentioned fluorocarbon-liquid,
>which has an oxygen substitute.
correct me if i'm wrong, but i believe that (at least in "the abyss") the
fluid was just a transport medium, carrying oxygen to your lungs. the
liquid just had some very high saturation point for oxygen. an early
demonstration i saw of this in the early 80's needed an aerator running
to keep enough oxygen dissolved.
there are a few problems, tho. one is that the stuff being so thick, you
can't speak. does anyone know that if the liquid had a lower viscosity
if it would help? or, is it a matter of how fast sound propogates thru
the medium? (my guess; you need to be able to vibrate your vocal cords)
also, i understood that there was some damage done to the lungs/throat when
you first use the stuff. in a future game, this and the above may very
well be worked out, but it could be an issue if its just beginning to be
used.
oh, and one more thing: pressure contributes to the amount of oxygen
dissolved in your tissues. lots of gravity (from acceleration) would give
you lots of pressure. oxygen poisoning happens at around 10 atmospheres
of pressure, assuming normal earth atmospheric makeup.
joe
--
"Once you can accept the universe as being something expanding into an
infinite nothing which is something, wearing stripes with plaid is easy."
Albert Einstein
David Schwartz
Fill it with that "liquid oxygen" like in the Abyss.
Truls Pärsson
Richard Adams writes:
>Acceleration affects are only harmful if they are uneven. If the accelerating
>affect works on all of your body (inside and out) unlike sitting in a rocket
>seat where it pushes you in the pack to accelerate you then there is no
>real problem.
>So one accelerating factor is gravity. Gravity works on the whole body, and
>assuming you are not trying to work against it, then there is no noticable
>harmful affect. ....
^^^^^^^^^^^^^^
Tell that to some one on a planet with 7G. This poor person would be die.
By the way I'm still wondering how one can avoid be crushed by the force
of high acceleration 20G or more. Or survive extended accelerations in the
range of 7G.
Thomas Schoene
> |> >So one accelerating factor is gravity. Gravity works on the whole body, and
> |> >assuming you are not trying to work against it, then there is no noticable
> |> >harmful affect. ....
> |> ^^^^^^^^^^^^^^
> |>
>
> Not if he isn't working against the acceleration (That of cource requires that
> the character in question was i free fall. The drop wont hurt you, the sudden
> stop at the end might)
Except that the human body must always work against gravity. Yo have to
breath, circulte blood and support the inscreased weight of the boby's
muscles, organs, etc. Under 7G you would anticipate that it would be very
hard to breathe especially for extended periods, blood would tend to pool
at the lowest piint in the body and the loads on ribs etc would be quite
high. I don't think you would break anything immediately but sustaine high
ge woul be a problem
For a possible solution see Haldeman's _The Forever War_. He uses a system
which suspends the body in a pressurized medium and also fills body
cavities using a surgically instaled valve. Accidents with this system are
ugly. Of course accelerations are somewhat higher.
Tom Schoene
James Steel
> gravitationally as normal mass and cannot produce
> an event horizon. Remember that "relativistic mass"
> depends on the frame of reference that the object is
> being observed from. This kind of difference from
> real mass is why physicists have moved away from
> using the term.
Oh well, back to the drawing board. Thinking about it
later I realise it couldn't possibly work like that.
Thank goodness! It avoids having a logically closed
universe and several other problems (like your destination
vanishing). I presume "relativistic mass" just stops one
from speeding up or slowing down too fast...
Mind you, it might work for a game in which no physicists
or mathematicians were playing.
James :)
This is not a .sig
Kenneth D Miller
>
>Richard Adams writes:
>
>>Acceleration affects are only harmful if they are uneven. If the accelerating
>>affect works on all of your body (inside and out) unlike sitting in a rocket
>>seat where it pushes you in the pack to accelerate you then there is no
>>real problem.
>
>>So one accelerating factor is gravity. Gravity works on the whole body, and
>>assuming you are not trying to work against it, then there is no noticable
>>harmful affect. ....
> ^^^^^^^^^^^^^^
>
>Tell that to some one on a planet with 7G. This poor person would be die.
Ah, but that's because they're being resisted by the GROUND. The uneven force
applied to the person by the ground (by their being pulled into it at 7G) is
what's causing them pain. Being in a 7G free-fall is no problem at all. Nor
is being in a 20G free-fall, or a 10000G free-fall. It's that pesky force
applied to your feet that causes the trouble.
And, indeed, since the person on the 7G planet is, in fact, resisting the
pull of gravity (the ground geing in the way), that person is illing quite
badly. Even more so at 20G
You seem to have neglected the first paragraph.
--
Ken! "Evil is afoot!"
"Really, that's very philosophical, Tick. A foot? I always
envisioned evil as a dark, brooding shape with sqinty eyes..."
Steve Gunnell
In article <1994Apr02.0...@ghidora.santa-cruz.ca.us> j...@ghidora.santa-cruz.ca.us writes:
> In article <2nailo$4...@vixen.cso.uiuc.edu> rsm5...@uxa.cso.uiuc.edu (Ron)
> writes:
> [stuff deleted]
> >in ABYSS, the movie, they had liquid gunk you could breathe. in one of
> >Asimov's technologies to watch guides he mentioned fluorocarbon-liquid,
> >which has an oxygen substitute.
> > - ron
> >--
> >(ron) rm9...@meibm10.cen.uiuc.edu
>
> correct me if i'm wrong, but i believe that (at least in "the abyss") the
> fluid was just a transport medium, carrying oxygen to your lungs. the
> liquid just had some very high saturation point for oxygen. an early
> demonstration i saw of this in the early 80's needed an aerator running
> to keep enough oxygen dissolved.
>
> you first use the stuff. in a future game, this and the above may very
> well be worked out, but it could be an issue if its just beginning to be
> used.
premature babies already. I don't know about the other problems.
-----------------------------------+-------------------------------------
Stephen Gunnell -----------------------------> ste...@eldred.dialix.oz.au
-----------------------------------+-------------------------------------
Jens-Arthur Leirbakk
Well, actually the liquid diving suit technology used in the Abyss actually exists.
Truls Pärsson
>>Tell that to some one on a planet with 7G. This poor person would be die.
>Ah, but that's because they're being resisted by the GROUND. The uneven force
>applied to the person by the ground (by their being pulled into it at 7G) is
>what's causing them pain. Being in a 7G free-fall is no problem at all. Nor
>is being in a 20G free-fall, or a 10000G free-fall. It's that pesky force
>applied to your feet that causes the trouble.
Not true as your body resists even if you're in free-fall. Of course you would
take less damage in free-fall than if standing on the ground. Now just think
of what would happen to you're bodyfluids in 20G free-fall. The only way is
to some how negate the effect of the accelration with a perfectly matched
anti-acceleration force.
Thomas Newton Bagwell
: >Ah, but that's because they're being resisted by the GROUND. The uneven force
: >applied to the person by the ground (by their being pulled into it at 7G) is
: >what's causing them pain. Being in a 7G free-fall is no problem at all. Nor
: >is being in a 20G free-fall, or a 10000G free-fall. It's that pesky force
: >applied to your feet that causes the trouble.
: Not true as your body resists even if you're in free-fall. Of course you would
: take less damage in free-fall than if standing on the ground. Now just think
: of what would happen to you're bodyfluids in 20G free-fall. The only way is
: to some how negate the effect of the accelration with a perfectly matched
: anti-acceleration force.
You're kidding, right? Sorry, but if you're accelerating in free fall
with no resistance (no air, etc.) Then your acceleration makes no
difference. Somebody falling in a 1 million G gravity field would feel
no different than somebody in 0 G. This is because the gravity is
working independently on every atom of the body simultaneously.
Carl D. Perkins
>You're kidding, right? Sorry, but if you're accelerating in free fall
>with no resistance (no air, etc.) Then your acceleration makes no
>difference. Somebody falling in a 1 million G gravity field would feel
>no different than somebody in 0 G. This is because the gravity is
>working independently on every atom of the body simultaneously.
With one little catch - gravitational fields are not uniform. If you are
falling towards an object (feet first, say) and at that point in time the
force at your center of gravity is 1,000,000g it could well be 999,995 at
your head and 1,000,005 at your feet for, effectively, a net 10g force trying
to stretch you...
The joys of tidal type effects.
--- Carl
Leif Magnar Kj|nn|y
Thomas Newton Bagwell <new...@indial1.io.com> wrote:
>
>You're kidding, right? Sorry, but if you're accelerating in free fall
>with no resistance (no air, etc.) Then your acceleration makes no
>difference. Somebody falling in a 1 million G gravity field would feel
>no different than somebody in 0 G. This is because the gravity is
>working independently on every atom of the body simultaneously.
...assuming a homogenous gravity field, that is. Most very strong gravity
fields are found close to very dense bodies such as neutron stars and black
holes; in these cases you could get close enough that the tidal effect would
rip you and your ship to bits.
--
Leif Kj{\o}nn{\o}y (lei...@kari.fm.unit.no)
"Take your cigarette from its holder, and burn your initials in my shoulder.
Fracture my spine, and swear that you're mine...
as we dance to the masochism tango." (Tom Lehrer)
Matthew Bassett
|> Truls Pärsson (par...@vaxkab.e.kth.se) wrote:
|>
|> : Not true as your body resists even if you're in free-fall. Of course you would
|> : take less damage in free-fall than if standing on the ground. Now just think
|> : of what would happen to you're bodyfluids in 20G free-fall. The only way is
|> : to some how negate the effect of the accelration with a perfectly matched
|> : anti-acceleration force.
|>
|> You're kidding, right? Sorry, but if you're accelerating in free fall
|> with no resistance (no air, etc.) Then your acceleration makes no
|> difference. Somebody falling in a 1 million G gravity field would feel
|> no different than somebody in 0 G. This is because the gravity is
|> working independently on every atom of the body simultaneously.
You are entirely correct... although I would suspect that the only place
you would find a G-field of 1 million gravities is near the bottom of a
very deep G-well (ie near a black hole?), where the strength of the G-field
changes a great deal over distance... in this instance the front half of
your body could be accelerating in a 1 million G field and the back half in
a 950 thousand G field... a difference of 50 thousand Gs which I should
think would cause quite a lot of damage to said body (for all you pedants
out there... so I'm mixing up force/acceleration and everything else to
hand - but you get the picture).
Yon fella above (Truls Pärsson) is mixing up the effects of forces applied
by a G-field, and forces applied by contact with an accelerating body (ie
the difference between being in free fall in a 20G gravity field and being
in a space-ship accelerating at 20Gs).
- Matt.
--
_______________________________________________________________________
Matthew Bassett Tel: 0235 446571
Rutherford Appleton Laboratory janet: mat...@uk.ac.rl.sa
Building R25, room 2-55 internet: mat...@sa.rl.ac.uk
Chilton, Didcot, Oxon, OX11 OQX, UK.
Alan Barclay
>
>
> You're kidding, right? Sorry, but if you're accelerating in free fall
> with no resistance (no air, etc.) Then your acceleration makes no
> difference. Somebody falling in a 1 million G gravity field would feel
> no different than somebody in 0 G. This is because the gravity is
> working independently on every atom of the body simultaneously.
>
If the character is being accelerated by some force of gravity, he does
indeed feel like he's in freefall. However, if he is in a spaceship,
which is doing the accelerating, the spaceship transmits the acceleration
to the character's body through contact with the ship. In this case the
character will feel every single newton of
acceleration.
/%{Alan
Spam El - Last Spam of Krypton
>You're kidding, right? Sorry, but if you're accelerating in free fall
>with no resistance (no air, etc.) Then your acceleration makes no
>difference. Somebody falling in a 1 million G gravity field would feel
>no different than somebody in 0 G. This is because the gravity is
>working independently on every atom of the body simultaneously.
one thing to consider is the gravity gradient; if there is 100 Gs at your
feet, but only 1 G at your head, you get turned into the amazing linguini. :)
yet another reason why falling into a smaller gravity source is so bad.
joe
--
There are four kinds of homicide: felonius, excusable, justifiable,
and praiseworthy... -- Ambrose Bierce
Fred and Evelyn Wolke
: : Not true as your body resists even if you're in free-fall. Of course you would
: : take less damage in free-fall than if standing on the ground. Now just think
: : of what would happen to you're bodyfluids in 20G free-fall. The only way is
: : to some how negate the effect of the accelration with a perfectly matched
: : anti-acceleration force.
: You're kidding, right? Sorry, but if you're accelerating in free fall
: with no resistance (no air, etc.) Then your acceleration makes no
: difference. Somebody falling in a 1 million G gravity field would feel
: no different than somebody in 0 G. This is because the gravity is
: working independently on every atom of the body simultaneously.
Free-fall, by definition, is a state of weightlessness. The sensation,
and effect, of weight is due to a force (such as gravity or acceleration)
that is resisted by some other force (such as the ground). A droplet of
water falling in a gravity field behaves EXACTLY the same as a droplet of
water that is not in a gravity field at all. The same applies to people.
The only exception to this is when the gravity field is not uniform, to
an extreme degree. If you were falling into a black hole, and your feet
were in a 1 billion-g gravity field, and your head, a bit farther out,
were in a 900 million G gravity field, you would be stretched out like a
piece of spaghetti. (A 100-million G force is a bit more than the human
body can take WHEN APPLIED DIFFERENTIALLY.) If you don't understand, or
don't accept this, take a high school physics course.