GURPS Space: Stardrives

[Diomedes]

Originally Posted by Anthony

Incidentally, I think this thread is going about the problem slightly backwards. We should start with discussing what features a plot-useful stardrive has, and then proceed from there.

Indeed.

I would say that useful plot features for a stardrive include:[list][*]Permits smuggling[*]Permits piracy, preferably including boarding actions

Smuggling requires the ability to go "off the trail" on routes the Navy doesn't patrol – so no point-to-point. It also requires the ability to get contraband down to the planet without getting caught, which is the real bottleneck, no mater what stardrive you use.
Piracy requires that the legitimate trade use those same unpatrolled routes, or a navy that is seriously under-resourced. Boarding actions aren't really affected by stardrive, unless you want them to actually occur in FTL.

[list][*]Is slow enough to keep events somewhat isolated -- PCs should be days or weeks from civilization, not minutes or hours.[*]Conveniently available on inexpensive, PC-scale ships.

Both of these are very good to have.

• On the opposite end of things, something keeps the interstellar population limited.

Realistically, it takes an awfully long time to grow interstellar colonies, unless you assume population growth rates will be considerably larger than they are now. Do we really need a limit?

[thrash]

Originally Posted by Anthony

One variant I've considered, which has some considerable utility with respect to solving Fermi's Paradox, is something sort of like a B5 drive, though more restricted.

This description also has some similarities to the drive used in Morioka Hiroyuki's Seikai no Monshou novels. See, e.g.: http://www.geocities.com/Tokyo/Shrin...ai/planar.html

[Fred Brackin]

Originally Posted by Anthony

The advantage, here, is that any place that a ship can exit hyperspace must be interesting, because the presence of a gate implies something capable of creating a gate

A similar set up I've considered is called the Swirlway. It is an artificial network of portals which always come in pairs. Access to the network is obtained by playing the tones from CE3K (or at least something like them) on a radio specific frequency. Entry and exit are non-dramatic.

This pair of portals would be approx. 400,000 miles ahead and behind a planet of Earth's mass. Note that this does not consist of an orbit. Keeping a sensor always on the portal is relatively easy. keeping an interception fleet within range is certainly possible. Even keeping a weapon always within range might be doable but you can't just sit on top of a portal without a something like a reactionless drive.

When you enter a portal you're on an Alpha line. This appears to be something like the inside of a tornado made of energy (hence the name). The Alpha line will connect relatively soon to a Beta line and perhaps eventually to a Gamma line and so forth. Sometimes higher level lines may connect directly to an alpha. There's a legendary Omega line out there somewhere. If you can make it to the Omega line you can go _anywhere_

To control your movement within the swirlway you must have what's called a "Turbo". The Turbo spins (rotary movement is very important to interstellar flight, see many TV shows) and contains the stored energy that you use to maneuver in the swirlway. As your turbo winds down (or runs out of "revs" in the local jargon) you need to get out of the swirlway or start a rough ride to a random place.

Unpowered swirlway riders always get dumped out _somewhere_ (or at least such is the local article of faith). If their ship was small and sturdy they might even be in one piece.

Most swirlway portals lead to habitable planets. Others lead to resource sites, places of scientific interest or for the very smallest cases (asteroids c. 100 miles in diameter with correspondingly close portal pairs) what may be hyperspace bypasses.

With known levels of technology turbos can not be recharged while in use. These leads to a pattern of short trips. In one alpha, down the beta to the next alpha and out again to recharge your turbo.

Sometimes you go right back in and up the same beta and sometimes you go from a leading portal to a trailing portal (or vice-versa)

High performance turbos (greater ratio of of turbo size to ship mass) can enable longer trips. So can high quality piloting. Swirlway navigation is complex, based on passive sensor input only and even that has a chaotic uncertainty factor.

An A.I. that can even equal to performance of a trained human is a very high order machine and probably more expensive than a trained pilot. P.C level pilots with Luck, Intuition and similar Ads can usually exceed any A.I.'s results.

The swirlway has probably been in existence for a few billion years or so and whether Earth life has been transplanted to other places or taken from other places and transplanted to Earth so long ago that it's blended completely in is an exceedingly difficult question to answer. Combinations of both repeated over a very long time are also possible.

How recently the Builders were doing this and whether or not there are Homo Sapiens or closely-related species beyond Earth and it's colonies is left to the individual GM. There could be intelligent dinosaurs or anything else out there as well.

It can be easily established that portal exits that are close to one another in the swirlway are not close to one another in normal space. Also, portals that are close to one another in normal space (i.e the leading and trailing ones) are very rarely close to one another in the swirlway system.

Can it even be proven that different exits are even in the same galaxy, universe or time? Not so far.

If anyone wonders this all came out of a thought experiment of what would justify the life pod in UT. The 400-500,000 mile distance from a habitable planet is the key thing.

[Diomedes]

Originally Posted by Fred Brackin

When you enter a portal you're on an Alpha line. This appears to be something like the inside of a tornado made of energy (hence the name). The Alpha line will connect relatively soon to a Beta line and perhaps eventually to a Gamma line and so forth. Sometimes higher level lines may connect directly to an alpha. There's a legendary Omega line out there somewhere. If you can make it to the Omega line you can go _anywhere_

So you go through the portal and travel down the line until you reach the appropriate exit, or jump to a higher power line? Is there just one Alpha line that can theoretically take you anywhere if you can stay on long enough, or do you have to switch via a Beta or higher to a separate Alpha line?

[Fred Brackin]

Originally Posted by Diomedes

So you go through the portal and travel down the line until you reach the appropriate exit, or jump to a higher power line? Is there just one Alpha line that can theoretically take you anywhere if you can stay on long enough, or do you have to switch via a Beta or higher to a separate Alpha line?

In my visualization Alpha lines are just feeders to higher order lines. You'll have to make at least 2 transitions (Alpha to Beta, Beta to new Alpha) to get anywhere.

Each transition would require a Piloting roll and margin of success would determine how many revs you have to spend to get across the turbulent juncture.

Bypassing a juncture would also require Plioting and expenditure of revs though not quite so much. A hot PC Pilot should be able to go a good deal farther than a safe corporate pilot or AI on the same amount of revs.

[Diomedes]

Originally Posted by Fred Brackin

In my visualization Alpha lines are just feeders to higher order lines. You'll have to make at least 2 transitions (Alpha to Beta, Beta to new Alpha) to get anywhere.

Each transition would require a Piloting roll and margin of success would determine how many revs you have to spend to get across the turbulent juncture.

Bypassing a juncture would also require Plioting and expenditure of revs though not quite so much. A hot PC Pilot should be able to go a good deal farther than a safe corporate pilot or AI on the same amount of revs.

How would you go about bypassing a juncture (between the Alpha and Beta lines, I take it?)?

Edit: Or to put it another way, is there some method of accessing the higher lines besides the junctures?

[Rupert]

Originally Posted by Anthony

Depending on the exact properties of hyperspace, this may support hyperspace pirates. If gates can only be detected at relatively short distances (relatively short on hyperspace scales, anyway) this also supports exploration. I'd also be strongly tempted to toss psionic powers into the blender, as some form of excuse to keep robotic probes under control.

The easy way would be to have it that only psionics can detect a gate at anything more than "we're on top of it" ranges while in hyperspace. The other way is to require psionic talent for hyperspace navigation. The former means psions are only needed for exploration, the latter means they're needed for all FTL travel and are therefore a likely limitation on ship numbers.

[tachyonic]

Originally Posted by Anthony

One variant I've considered, which has some considerable utility with respect to solving Fermi's Paradox, is something sort of like a B5 drive, though more restricted. The basic way it works is that ships can only enter or leave hyperspace (or whatever you choose to call it) at a jump point, and that jump points are (a) normally synthetic, and (b) last pretty much forever once created. My instinct is that a jump point is either just a micro black hole, or perhaps something more exotic like a ring singularity, but either way, is pretty much indestructible once created. Creating such gates probably implies gravitic superscience, though not necessarily anti-gravity or full-fledged creationless drives as such (tractor/pressor beams, or perhaps force beams, seem more likely). It would be nice, if a good handwave can be found, if the region in which you can enter/leave hyperspace is fairly large (planet-sized), as that makes smuggling more practical. You can also sensibly handwave size limits on ships, or even throughput limits on jump points.

The advantage, here, is that any place that a ship can exit hyperspace must be interesting, because the presence of a gate implies something capable of creating a gate -- at least, sometime within the last fourteen billion years. It also means you can have alien races who haven't contacted Earth, and maybe don't know about us, because we haven't created a gate.

Depending on the exact properties of hyperspace, this may support hyperspace pirates. If gates can only be detected at relatively short distances (relatively short on hyperspace scales, anyway) this also supports exploration. I'd also be strongly tempted to toss psionic powers into the blender, as some form of excuse to keep robotic probes under control.

You're assuming that Fermi's paradox is real!

[David Johnston2]

Originally Posted by tachyonic

You're assuming that Fermi's paradox is real!

Logic is not an assumption.

IF the galaxy is filled with aliens

and

IF it is possible to travel from star to star

THEN aliens would already be here.

THEREFORE:

The galaxy is not filled with aliens

OR

It is impossible to travel from star to star

OR

The aliens are already here.

The first option is no fun. The second option is also no fun. The third option is fun but raises the question...if the aliens are here, why are we here? After all, by all rights a galaxy filled with aliens would contain aliens who got here first and therefore would have occupied our planet before we did.

[Ulzgoroth]

Originally Posted by David Johnston2

Logic is not an assumption.

IF the galaxy is filled with aliens

and

IF it is possible to travel from star to star

THEN aliens would already be here.

THEREFORE:

The galaxy is not filled with aliens

OR

It is impossible to travel from star to star

OR

The aliens are already here.

Er, no. Adding spurious if-then structure does not make an assertion into unassailable logic. Your premises do not lead to your conclusion without additional unstated premises.

It might be legitimate to say that it is likely that in a universe with lots of aliens and practical means of interstellar travel, the aliens would have come here already (Though space is big, so we could just be missed). However, there is no reason the universe has to be likely.

-We might be the elder race. The galaxy might be full of alien life, all of it a few thousand or million years of development behind us.
-It might be that despite all of the smart aliens out there, and the physics allowing FTL, none of them have hit on just how to do it.
-We might be totally englobed by an empire that considers our star holy/forbidden/boring, for some reason.
-We might not be on the FTL network.
...just for a few. All of them would be amazing coincidences. Amazing coincidences do happen.

Originally Posted by David Johnston2

The first option is no fun. The second option is also no fun. The third option is fun but raises the question...if the aliens are here, why are we here? After all, by all rights a galaxy filled with aliens would contain aliens who got here first and therefore would have occupied our planet before we did.

Anthropic principle, if nothing else.

Not to mention that they might be us, they might not want our planet, they might be here in some way we haven't noticed... (Stargate based civilization of gas giant dwellers? We'd have no clue.)