Alternate Ship Design Systems

[Drakon]

Originally posted by Tom Kalbfus:
On the other side of the coin, time travel also solves some problems like the number of habitable planets. I think in a realistic setting, habitable planets won't just happen. Planets may have life on them, but that won't necessarily make them habitable for us, it would only be habitable for the life that evolved their.

I think we are going to have to agree to disagree here, until we get further data. I don't think there is any other way to get life bearing planets, except via carbon chemistry. I also think that Lovelock is convincing in his argument as to how biospheres will alter their environment in order to make it more livable.

You might bring up the parity issue, how even though sugars and amino acids can be either "left haned" or "right handed" and how life on earth has selected one set. (I can never remember which, but I think it is right handed sugars and left handed amino acids. I am sure I will get corrected). But I note that there does not appear to exist ANY life forms on this one planet that uses the alternative parity. It very well may be something we are missing that prevents life forms of the opposing parity.

Also the search or extra-terrestrial intelligence has so far been unfruitful, I think that says something about our immediate stellar neighborhood.

There are several possible solutions to this problem, only the most obvious is that we are alone.

There is a big problem with SETI, in that it is as likely to be dangerous, if successful, as useless. Suppose we do make contact, find out the there is an interstellar civilization say, camped out at Wolf 359. Do we really want to tell them we are here? If they are hostile for any reason whatsoever. They just don't like our hair styles, for example. How would we defend ourselves as a planet, a nation, a species if they decided they wanted to kill us?

We couldn't. You know that Aricibo has broadcasted twice specifically to extra-terrestrials. But the first time was to the Andromeda Galaxy, the other to a distance star cluster, really unlikely to have habitable planets anyway. In both cases, to me, it looks more like we were NOT trying to broadcast to a potential ET, that it was done for show to get the SETI folks off their back.

If the civilization we contact has starflight, we are potentially in very big trouble. Alerting them to our presence could be essentially signing our own death warrents.

And if the civilization we contact does not? Would they want to talk to us, alerting us to their presence, with all the potential for disaster that could induce?

And there is the issue of the Brookings Report on the effects that finding an ET would have on our own culture and society. Even if it is a worst case scenario, it is still too high a price to pay compared to the likely benefits.

Now, toss into the mix that SETI has only been around for what, A few decades, a mere blip of cosmic time, and it is hardly surprising that SETI is a failure. But such a failure means nothing.

Most planets we would encounter would not be suitable for habitation without major modification (terraforming).

Again, I think I am more optimistic here than you are. And until and unless we get out there and actually LOOK, this debate cannot be settled.

Tell ya what, whichever of us gets their FTL drive system working first, takes the other out to settle the question. Deal?

But, if I am right, then time travel is not needed to fix the problem you present. I think you mistaken, and I kind of get the impression that you do too in a manner of speaking.

Your Traveller Universe may vary.

There are some things in physics that hint at the possibility of time travel, and opther things that hint at the possibility of parallel realities. Everytime you roll a dice, maybe there is a universe where you rolled a 2 and another one where you rolled a 3. As for the conservation of mass, we don't know if that applies to the Universe as a whole. The expanding multiple realities might just be another part of the Universes expansion.

I have never been comfortable with Everette's Multiverse. In practical fact all it does is sweep a question under the rug, much like Copenhagen does with QM. Bohm, explicitly demands time travel to make any sense. I don't see it as realistic, and don't get me started on the problems inherent in QM, (or rather the interpretations of QM, which is different. Its one thing to say, if you do this, that will happen. Its another to say, becuase the cat is both alive and dead at the same time.)

Warp drive has something to be said for it. One way to warp space is with an antigravity field. The general theory of relativity states that a gravity field would slow down time. Suppose you surrounded a spaceship with a transparent sphere and that sphere created a powerful antigravity field. Looking outward from that sphere would be similar to looking down an immense gravity field.

Assuming that is how you construct the field, but this is not quite right for the Alcubierra model.

The sphere inside the bubble would be flat. (Actually you could alter this to create a comfortable 1 G field as felt by objects inside, but we'll come back to that later) The walls of the bubble would be bent. If we are using the rubber sheet analogy, the walls bend "down" and then back "up" So not only are you looking dow an gravity well, but also up a reversed one as well.

Again, look at Hiscock's paper I refered to earlier. He lays out just how things would look from the bridge of Alcubierre's starship.

Since time would move faster in the starship light would move faster with that accelerated time.

What is wrong with this sentence? You forgot something. Time is not the only thing that changes. Space changes too. The speed of light stays constant, becuase of the change in both time AND space.

How does that sound as a warp drive? Of course it would tend to push things waya from itself as well.

Not bad. Not as good as Alcubierre or the rest of that discussion. I noted one bug you have.

The thing is that while you are altering the metric, you want to do so ONLY on the bubble walls. There are no rules in GR, or really known, that prevents the warp bubble from travelling at any speed we wish. Because what the bubble is, is space-time itself, it is not limited to the speed limit that particles inside that manifold are limited to.

The ship and the contents of the bubble don't go anywhere. For them, their local space is flat, and they ain't moving. But because they are in a warp bubble doing 5 light years a minute, they effective are travelling faster than light, even though they ain't moving at all. (With respect to their own local manifold.)

 

[TKalbfus]

"If the civilization we contact has starflight, we are potentially in very big trouble. Alerting them to our presence could be essentially signing our own death warrents.".

Most likely FTL travel is impossible, the civilizations starships would be like the STL Scout/Courier I listed above. I estimate if the civilization had cheap antimatter it would cost about $1 billion per ton of anti-hydrogen, if it were much cheaper than this civilization would destroy itself with pocket antimatter bombs that escaped government control. In any casy my starship above would require $13 billion worth of antimatter. Sending out one shuch ship is almost the size of NASA's annual budget, the price of the actual ship is insignificant compared to the cost of its fuel. If that civilization lived on Alpha Centauri, it would take 82 years to get here. If it didn't slow down, it could get here in 41 years and then it could crash into Earth at 0.1c Assuming its displacement mass is its mass, that could release quite a bit of energy. I think any civilization on Alpha Centauri would already be alerted to any technilogical civilization on Earth if they had radio communication.

 

[Drakon]

Originally posted by Tom Kalbfus:
All warp ships would also have force fields that protect it from micrometerites, and laser beams would be redshifted to harmlessness unless they exceeded a certain intensity.

Umm.. not sure we really want to talk about this subject, as ANY FTL ship is going to require shielding. Something that Traveller does not worry about.

There is something called, (I think) Urhuh radiation. What this is, is that the temperature of the universe is 2.3 kelvin, and can be represented by very long wavelength photons. As you speed up, their apparent wavelength decreases, and hence apparent temperature increases. At light speed, you are inside a sun, only hotter.

Any shielding technology you come up with to circumvent this problem is applicable in military situations. Meaning that if you have the required shielding for FTL, lasers and other energy weapons will be useless against you. And because of the gravitational shear of the bubble walls, rockets and other material weapons would be useless as well.

If you want to know more (Why is the TV announcer from "Starship Troopers" inside my head?) go to the LANL archives at http://xxx.lanl.gov/find/gr-qc and do a search (in the abstract and/or title field) for "Warp Drive" It should pop up about 13 or so papers.

You also want to select "All years" and "Search all" at the top.

Energy requirements originally were upwards of 4 jovian masses, complete conversion, to even get the ship to light speed, but later developments indicate that this is not true.

The "anti-gravity" part of the bubble actually only encompasses the aft end of the bubble. The forward section has to be, well, "gravity" for lack of a better word. You collapse or compress space-time in front, (meaning that space shrinks as time slows down) and expand it behind the bubble. (Length increases, and time speeds up). But again, only in the walls, in the transistion region between the outside universe, and inside the warp bubble.

 

[Drakon]

Originally posted by Tom Kalbfus:
Most likely FTL travel is impossible, the civilizations starships would be like the STL Scout/Courier I listed above.

Well I won't go that far yet. Again, I see a work around, that makes it possible. Call me optimistic, but I can think of few things more depressing than stuck forever on this single rock. Or even in this single solar system.

I think any civilization on Alpha Centauri would already be alerted to any technilogical civilization on Earth if they had radio communication.

Had this discussion with a co-worker who is a ham as well. According to him, none of the signals, with the possible except of radar, would make any sense beyond about 1 or 2 light years, as it gets garbled in the noise that is already out there.

The big reason why SETI uses the 21 centimeter band is that the universe is so quiet at that frequency. They figure that with all the noise on any other frequency, it is a safe bet to listen to this dark area of the spectrum.

I say except for radars because its pulsed nature might give it away.

And a civilization on Alpha Centauri means not just that, but one that has developed radio technology and even bothering to listen to us. Just because you got a life bearing planet does not necessarily mean that such life will develope intelligence, or that such intelligence will rise to the point of discovering radio communication. There are a host of socialogical reasons I can think of, using our world examples, why it is not necessarily true that any such civilization will even think to listen.

 

[Drakon]

Originally posted by Tom Kalbfus:
it will take 509.25 years to return to Earth from Alpha Centauri to give an example, but the crew has its cold berths and can wait that long, but it can beam back all the data it has gathered back to Earth at the speed of light, so those whove sent out the Scout ship get their information back in 88.4 years and that's what's important to the investors or taxpayers back home.

And this is why it will never happen.

Look at how much human civilization has changed in the last 500 years, let alone 88. How much history and change has occured.

The folks flying this ship will never return home, they will be returning to a completely new and different earth, only somewhat related to the one they left. Look at how much human language, especially english has changed. They won't even be able to speak the language.

So any such slower than light trip is effectively one way. Whatever they come back to will be way to radically different from what they left that it would be stretching things to the limit to call it "home"

 

[TKalbfus]

"So any such slower than light trip is effectively one way. Whatever they come back to will be way to radically different from what they left that it would be stretching things to the limit to call it "home""

Precisely, the exploration of Alpha Centauri is just a prelude to where the real adventure begins.
You begin with a mission to explore another star system, perhaps conducted by a futere descendent of NASA say starting in the year 2100. By 2184, the crew arrives and does a detailed planetary survey and perhaps has a few adventures there. At this point the mission is complete, they send the data back to Earth and NASA officially signs the title of the Starship over to the crew. The crew can either stay in the Alpha Centauri System and perhaps wait for the next mission to arrive or they can return home using their slower fusion rockets. There is no way they can get anymore antimatter. So using locally available hydrogen, they can refuel and head home. 500 years would pass, just like for Buck Rogers, and the Solar System is a different place when they arrive, but at least they be back among humanity and they may indeed be rich, just think of all that accumulated interest in their bank deposit. All their pay has accumulated in their bank accounts for 84 years.

 

[TKalbfus]

I envision a Solar System with a "minigalaxy" of space colonies. You would generate the colonies just as you would UPP in Traveller except that you generate the social data first and then fit the space colony type to suit.
A Small Space colony would be a Space Station of the type seen in "2001 A Space Odyssey" It is a wheel shaped building in space with apartments, offices and perhaps some green houses, these would be suitable for populations of 3 and less

Population 4 would be an Island One Space Colony - basically a sphere about 1 mile in circumference or alternately a Stamford Torus.

Population 5 would require a larger cousin of Island One - A Bernal Sphere or Island Two, it is a larger sphere of about 5 miles in diamter

Population 6 and 7 would be Island Three Colonies, these are rotating cylinders 5 miles in diameter and 20 miles long often linked in counter-rotating pairs for stability

Population 8 would be lets call it Island Four - a pair of cylinders 20 miles in diameter and 80 miles long.

Population 9 would be Island Five - A pair of cylinders 80 miles wide and 320 miles long.

A more affluent Population 9 might crave more space so it might have a pair of cylinders 500 miles wide and 2000 miles long.

Being artificial worlds, atmospheres would be 6 and hydrographics would be 3 to 5 on the inner surface of the cylinders. Then there would be the Terraformed Mars, and Terraformed Titan. Whole Nations would rise up in place of the ones familiar to the explorers. I wouldn't advance the tech much as its already advanced enough, so the returnees wouldn't be at too much of a disadvantage.

 

[Drakon]

Originally posted by Tom Kalbfus:
Precisely, the exploration of Alpha Centauri is just a prelude to where the real adventure begins.

You seem to be missing my point. Because of the changes we are talking about, it is a one way mission. The kind of psychology required for space flight may not be compatible with folks who want to leave earth and NEVER COME BACK.

The guys who would be qualified to do the mission, you really want to keep around and don't want to, in essence, throw them away. And they probably won't want to throw their lives away or alter them in such a total fashion. The guys that can, you want to keep, and won't want to go.

The guys who want to go, well, what kind of person would be so willing to alter their lives so radically and completely? I doubt it would someone who would be able to complete the mission.

Or, as my dad once said, "There are a lot of crazy people, and a lot of stupid people. But there ain't that many folks that crazy AND that stupid."

Concerning your ideas on space colonies, I think you have something. Cost is a major factor however, as these things are going to be expensive. (Of course by 2100, or 2200, that cost should come down markedly) And that means working out a decent business plan. You planning on selling the land inside the colony, giving the colonists a stake in how it goes? How would you work that?

 

[TKalbfus]

"You seem to be missing my point. Because of the changes we are talking about, it is a one way mission. The kind of psychology required for space flight may not be compatible with folks who want to leave earth and NEVER COME BACK.

The guys who would be qualified to do the mission, you really want to keep around and don't want to, in essence, throw them away. And they probably won't want to throw their lives away or alter them in such a total fashion. The guys that can, you want to keep, and won't want to go.

The guys who want to go, well, what kind of person would be so willing to alter their lives so radically and completely? I doubt it would someone who would be able to complete the mission."

Well without those guys, you don't have a mission. Realistically all interstellar missions are one-way in the sense that you can never return home to the place you grew up, but then again that's always true in a sense. I can never return home to where I grew up, the people who used to live their no longer do. The same houses are there and their are more houses there that were buiild since I left. After 600 years that would even be more true. But it's not necessarily a total sacrifice for the crew members. Loved ones and family members can also go into low berths on Earth as they wait for the crew members to finish their mission and return home. I'm assuming that low berth technology is safe and reliable, more reliable than the standard Traveller setting assumes. Large fractions of the population might use low berth technology and not just for transportation. So there maybe considerable numbers of 500 year old people. And what about technology? Were assuming TL17 minus all those technologies that blatantly defy the laws of physics. There is no gravity control, and no FTL. But Artificial Intelligence does exist and would become a major issue by 2700 AD. There is a delicate balance here, AI robots can built whatever is requested of them including other AI robots if given the energy and materials, this situation may not be healthy for humanity in General, so some work may be reserved for humans. I think robots can build giant space colonies if the criterion is that robots work where humans cannot without space suits, but once a suitable environment is created where humans can work in comfort, then some work is reserved for humans. This situation might styfle creativity over the longrun so technology won't change much over the time the crewmembers are gone, it would be TL17 when they left and TL17 when they returned. The only things that may be different would be language and culture. At TL17, technology is where it needs to be and doesn't need to go higher, why should it? With AI that can build anything that is technically buildable, what else do you need? The tech level tables don't go higher than tech level 17 anyway. It may be at TL18 where FTL is finally developed, but the impetous for developing it is small. The Solar System contains alot of room. There is certainly room for the 11,000 worlds of the Imperium if you don't mind artificial worlds. If you use the Traveller Method for generating UPP, then the average population would be in the range of 100,000 to 999,999 and a Bernal Sphere could accomodate this. The only thing that may be drastically different is if the Tech Level went down, not up. Humans could be so dependent on Robots and computers than when some unforseen disaster happens such as a ranpant computer virus, the humans might not have retained the skills to rebuild and maintain the technology that robots always took care of. The 11,000 space colonies might still be there, but their wouldn't be enough humans to build more. With things like nanotubes, for instance space colonies can get huge, even as big in size as planets in some cases. The same technology used to build space elevators can also supply the supporting cables for giant rotating cylinders that are 10,000 miles in diameter. Most of the volume of those cylinders would be empty space as even the atmosphere would be kept away from the center of the cylinder by centrifugal forces. A spaceship can fly inside theses cylinders as their sides would be open to space, as they would need only enough wall to prevent the atmosphere from spilling over the sides and no more than that. With fusion power, there is no need to be near the Sun.

 

[Straybow]

Well I won't go that far yet. Again, I see a work around, that makes it possible. Call me optimistic, but I can think of few things more depressing than stuck forever on this single rock. Or even in this single solar system.

Better stock up on Zoloft, 'cause we aren't going anywhere in the next hundred years or so.

Had this discussion with a co-worker who is a ham as well. According to him, none of the signals, with the possible except of radar, would make any sense beyond about 1 or 2 light years, as it gets garbled in the noise that is already out there.

Make sense, no. Clearly indicate a radio source orbits Sol at distance appropriate for liquid water, yes. They wouldn't be watching Gilligan's Island ("Oh, those poor people&#133 ) but they would know a technological civilization is here.

 

[Straybow]

I don't have a reference with me at the moment, but I thought the Alcubierre method was essentially collapsing space to nothing in front and expanding space in its wake.


If that is correct, then an Alcubierre ship doesn't need to repel anything. Microwave background, gas and dust won't become gamma rays, particle radiation and meteorites, they will be subsumed in the collapsed space. The "new" space in the wake will contain a similar energy level of microwaves and pair particles.

My impression is that while travelling thus the "bubble" manifests in normal space as a two dimensional disk. There is no "real space" distance between the frontal collapsing face and the rear face where space is reconstituted.

 

[TKalbfus]

Picture this, take a map of charted Space and superimpose it over a map of the Solar system on a scale of 81,000,000 km per hex. If you go 20 hexes away from the sun, planets and space station stay in their hexeover a long period of time. Saturn, Uranus, Neptune, and Pluto will remain in their hexes over any period of time the Players will be concerned with. Now imagine every planet depicted in the spinward marches map is actually a space colony in the Kuniper belt or inner Oort cloud. These space colonies are so far away from the Sun in their orbit that they remain fixed to a particular location in space, there is no need to draw orbits for each of them. In fact being out among the comets is a preferred location since fusion fuel is plentiful and easy to obtain out here. Use the same UPP but interpret them this way: If the atmosphere is breathable, then the planetary size digit matches the diameter of the space colony, otherwise, the space colony is large enough to suit the population it houses and no larger. In other words, a Bernal Sphere 5 miles wide would house a population of 100,000 to 999,999.

 

[Drakon]

Originally posted by Tom Kalbfus:
Well without those guys, you don't have a mission. Realistically all interstellar missions are one-way in the sense that you can never return home to the place you grew up, but then again that's always true in a sense. I can never return home to where I grew up, the people who used to live their no longer do.

I think you miss the point. The degree of change between your home neighorhood from when you were born to now is trivial compared to all the changes that would occur on earth over about 500 years. EVERYONE you knew would be dead. As would their children, their grandchildren and great grandchildren.

Your point about low berthing here on earth, I don't see as too realistic. Well low berthing in general, outside of a long trip, I see as pretty far fetched.

You go through a list of technical items that frankly seem to validate my point. Robots, space colonies, all of this will be brand new to the returning crew, even if they had been around for 400 years.

And if tech level collapses, that will present a whole host of different problems.

 

[Drakon]

Originally posted by Straybow:
Make sense, no. Clearly indicate a radio source orbits Sol at distance appropriate for liquid water, yes. They wouldn't be watching Gilligan's Island ("Oh, those poor people&#133 ) but they would know a technological civilization is here. [/QB]

According to him, no. The signals get too scrambled to make any sense. I don't know if he is right or not. But one thing I have heard is the biggest radio source in the solar system is Jupiter, not Earth.

With optical interference, (as I understand it) you will be able to detect Earth, and note its atmosphere. If you have oxygen in the atmosphere, that indicates life. (Without life, oxygen tends to get locked up in rocks, rust, carbon dioxide etc.)

It is my understanding that you have to get pretty close, withing a couple light years in order to see Gilligan, even as fuzzy and distorted as it would be. Again, air search radar is another can of worms, and THAT might indicate intelligence.

 

[Drakon]

Originally posted by Straybow:
I don't have a reference with me at the moment, but I thought the Alcubierre method was essentially collapsing space to nothing in front and expanding space in its wake.

[qb] Not to nothing, however the transition zone has to be very thin. But yeah, as I understand it, (and I ain't built one yet, soo...) you are correct.

[qb]If that is correct, then an Alcubierre ship doesn't need to repel anything. Microwave background, gas and dust won't become gamma rays, particle radiation and meteorites, they will be subsumed in the collapsed space. The "new" space in the wake will contain a similar energy level of microwaves and pair particles.

Again, I am not as much as an expert as I would like or to make more than partially educated guesses. But I will note that Hiscock's paper on "the view from the bridge" does show that one can see out.

In other words, light can pass through the transition zone, and impact the ship. So, if light can do it, despite the gravitational stresses, it seems reasonable that other objects like sub-atomic particles, rocks or high energy gamma, (which is light after all) can do it to. Unless some modification is made to use the warp drive bubble as a shield.

My impression is that while travelling thus the "bubble" manifests in normal space as a two dimensional disk. There is no "real space" distance between the frontal collapsing face and the rear face where space is reconstituted.

Hmmm... I had not really thought about it like that. It would be a very distorted region of space, and you might very well be right. It might look just like a disk.

 

[TKalbfus]

"I think you miss the point. The degree of change between your home neighorhood from when you were born to now is trivial compared to all the changes that would occur on earth over about 500 years. EVERYONE you knew would be dead. As would their children, their grandchildren and great grandchildren.

Your point about low berthing here on earth, I don't see as too realistic. Well low berthing in general, outside of a long trip, I see as pretty far fetched.

You go through a list of technical items that frankly seem to validate my point. Robots, space colonies, all of this will be brand new to the returning crew, even if they had been around for 400 years.

And if tech level collapses, that will present a whole host of different problems."

Problems are the meat of an Adventure. Adventuring is all about problem-solving. Utopias are boring, so I wouldn't want the PCs to return home to a Utopia where everyone peacefully coexists and all problems are solved by AI. The idea behind Traveller is to have many different worlds to visit. The usual solution is to incorporate a type of FTL drive so relatively inexpensive starships can visit the stars. Absent FTL you could simply create a "galaxy" of artifical "worlds" (cylinders) that rotate for gravity within the Solar System. The Solar System as I define it stretches outward from the Sun to a distance of 1 light day in all directions. To make mapping easier, we'll assume all of the orbiting space colonies are in the plane of the ecliptic and most of these colonies will be out beyond the orbit of Pluto so we don't have to track the in their orbits, we just put each in its own 80 million km hex and they stay there as there orbital velocity is very slow at this distance. An interstellar mission is a great way to introduce the PCs to this future Solar System. But lets say, instead of visiting Alpha Centauri, they visit a more distant Star System, Say Delta Pavonis 18.6 light years away, it is a single G6V lone star with a luminosity equal to the Sun. Figure it will take 338 years to get there and 2113 years to return for a total of 2400 years, plenty of history to develop the setting with. Also figure that those years weren't marked by a steady march of progress. For the out bound journey, alternatively assume multiple antimatter rocket stages were used to reach a maximum velocity of 0.2c, so the outbound journey is again 84 years. Total round trip is then 2200 years. The crews tech level starts out at TL17, the Solar System's tech level starts at TL 17, rises to TL 21 and then collapses so that each world now has a tech level that ranges from TL 0 to TL 17. The worlds are so big that they have self sufficient eco systems that require little maintenance, or they self-maintain themselves to a degree that they don't require human intervention.

 

[Straybow]

At TL17 usage of paragraphs should be normalized, and refined to a veritable artform by TL21. Unfortunately when civilization collapses, paragraphs will again become "optional" formatting.

nudge, nudge; know what I mean?

 

[Drakon]

Well, if you want Adventure, hanging around or beign stuck in a single ship does not sound all that adventurous. Especially if that ship is all alone on its trip to Delta Pavonis. The "galaxy of colonies" sounds intriguing.

I still don't like the idea of antimatter rockets. Call me crazy, but those things are just begging for a major catastrophy.

And I think Straybow is slightly off. I thought paragraph formatting had become standardized by TL4 or 3, rather than TL 17

 

[TKalbfus]

If you want to go anywhere close to an appreciable fraction of the speed of light in a self contained starship, you need Antimatter. A starship similar to the type used in traveller that is reusable, no "mission control" requirements, no expendable stages, requires an very energetic source of energy. Fusion, although it powers the stars, is not quite enough. Unless most of the ship's mass is comprised of fusion fuel, you can't expect to go higher than 1% of the speed of light. With an ideal matter/antimatter rocket, you propellent mass fraction is the highest velocity you can attain as a fraction of the speed of light assuming that you don't have to worry about slowing down.
Now lets say that 20% of your starship is payload and structural mass; then 40% of it will by hydrogen and the other 40% will be anti-hydrogen. 80% of the ship's starting mass will be converted to energy so if you use that energy with 100% effeciency to accelerate without decelerating, you can expect to achieve 0.8 c. Now since you may want to slow down, your maximum practical velocity would be 0.4 c for the ideal starship. Since an ideal starship may be unattainable, lets then assume that mass is converted to energy with 50% efficiency, in such a case, you can expect to achieve a maximum cruise velocity of 0.2 c with 80% of the ship's mass comprised of matter/antimatter reactants. Fusion can achieve 0.01 c max.

There are other ways to achieve high velocities.

One way is to have a laser sail propelled by a giant laser beam back in the system of origin.

The interstellar ramjet is a bit problematic.

Neither kind of starship is really suitable for a PC group. Most starships of this sort are controlled by an outside agency with the destination and mission predetermined. Their is little freedom to go on to the next system.

If antimatter was cheap and common, society would be in dire peril. The energy requirements for interstellar travel within a human lifetime are huge! One way to avoid this problem is to put everything thats interesting within a single Solar System, that way you can have spaceships operated by PCs that are affordible and maintainable by those same PCs, and powered by mere fusion engines. No FTL is required, no "rubber science", you just have to place the setting far in the future so that there are alot of interesting artifacts to uncover. Another option is to have a prior civilization that left alot of permanent wormholes in its wake.

 

[Drakon]

Originally posted by Tom Kalbfus:
If you want to go anywhere close to an appreciable fraction of the speed of light in a self contained starship, you need Antimatter.

False. But I can see where you get that idea. The amount of reaction mass, or energy producing fuel is enormous for travel through standard space. However, this may not be the case when gravitational technology enters into the picture.

have you done an energy calc on Traveller power plants? Take a look at how much energy is consumed in 1 jump, from just the fuel on board. We are talking enormous power outputs, and one of the noted bugs in Traveller. The energy usage is astromonical, even if it is just fusion. (Which is why some folks assume part of the jump fuel is used to create a plasma bubble)

I know a little something about manufacturing antimatter. And it ain't cheap and don't look to be in the foreseeable future. Massive amounts of antimatter simply do not exist, and frankly I don't think you will ever be allowed to produce sufficient quantities anywhere near a habitable planet. The stuff is just too dangerous. One false step, one tripped breaker or shorted magnet, and BOOOOOM!!!!!!!!. Only much much bigger.

And if you got wormholes, again the technology to create those ends up beign the same kind of technology required for warp drive.