Improved Poll: When should Civilization IV end?

[lajzar]

Originally posted by Plotinus
Darkcloud, as lajzar points out, you are underestimating what would be involved in really going to another star system.

...

The diameter of the Earth is 12,756 kilometres. The Moon is approximately 384,400 kilometres away (about thirty times the diameter of the Earth). The Sun is 149,597,892 kilometres away (11,727 Earth diameters).

Alpha Centauri, by contrast, is approximately 40,680,305,690 kilometres away. That is 105,828 times the distance to the Moon.

Its not just Darkcloud who underestimates interstellar distances. You did too. As a rough estimate, AC is 4.2 light years, or 462000 astronomical units away. An au is teh distance from earth to the sun, and 462000 of those is quite a bit farther than 105828 earth-moon distances.

Basically, once you start talking interstellar distances, the numbers get ridiculous if you plan on actually travelling there.

Let's play the numbers game. The current generation of liquid hydrogen rockets have an ISP of about 500 or so. The most optimistic estimates for fusion rockets is for an ISP of 50000 - 100 better than the best tech at present. For reference, an ISP of [n] means 1 ton of fuel will accelerate 1 ton of payload to [n] metres per second. Of course, half of that payload is the fuel itself, so the maths gets kinda funky.

Fortunately, I have a formula right here

dv = change in velocity
Isp = specific impulse of engine
Ve = exhaust velocity
x = reaction mass
m1 = payload mass
g = 9.8 m / s^2

Ve = Isp * g
dv = Ve * log((m1 + x) / m1)
= Ve * log((final mass) / (initial mass))

Kinda hard to understand I admit. So I made a spreadsheet, and plugged in some numbers. Lets use that fusion rocket with an isp of 50000 (100x better than teh best conventional rocket remember), and lets assume that 99.9999% of the rocket is fuel; 1 part per million is payload. Bear in mind however that half the thrust will have to be used to slow down.

Plugging those numbers into the formula, we are just shy of a top speed of 0.5% of c. Given the triangle shape that would illustrate aceleration:time, we could expect an overall travel time of, oh, about 850 years.

Nothing to interstellar travel really

[Roman]

Indeed lajzar, and the assumptions you made were ridiculously optimistic.

1) We are not realistically going to get an ISP of 50,000 from fusion engines (which we incidently do not yet have at all).

2) Making a spaceship that is 99.9999% fuel by mass is mind boggling to say the least. I would say that it is actually impossible Remember that the 'payload' is not just the humans, supplies and their life support systems within the ship, but also the entire ship itself, including its frame, engines, the huge fuel tanks it carries to hold the fuel, power generators and their fuel (you cannot rely on solar beyond about Mars) etc, etc, etc!

3) The ship (even disregarding the fuel) would be absolutely huge, as it would have to carry sufficient number of people to assure reproduction without degeneration for many generations of travelling time.

4) Although you mentioned using it, you forgot to use the acceleration triangle. Using the simplified constant acceleration assumption, we have to double the travelling time to about 1700 years.

5) Within 1700 years, there would be a very high probability of an accident happening on the ship that would be lethal to the entire crew in the hostile environment of space. The Mir space station almost crumbled within 20 years of its creation and it certainly had numerous close calls as well as less serious accidents. Simply put - man-made things do not last long enough to survive the journey.

6) Even disregarding all of the above, there is an overwhelming likelihood that the mission would fail as a result of tension within the crew. It is hard to keep interpersonal relations brilliant for 1700 years in confined space!

7) As has been pointed out Alpha Centauri is unlikely to have any hospitable planets.


On the other hand, we do not know what kind of technology will be discovered in the future that may depend on physical laws that we do not yet understand. Breaking 'c' might not be possible, but there may be ways to cheat (think wormholes, or possibly other as yet undiscovered physical phenonema)!

[lajzar]

Originally posted by Roman
Indeed lajzar, and the assumptions you made were ridiculously optimistic.

1) We are not realistically going to get an ISP of 50,000 from fusion engines (which we incidently do not yet have at all).

That estimate is from various pundits involved in the Traveller SF RPG. Given that more than one of these people is a qualified rocket scientist in his own right, I am inclined to believe that group. Of course, we are still nowhere near controlled fusion as you so rightly point out.

2) Making a spaceship that is 99.9999% fuel by mass is mind boggling to say the least. I would say that it is actually impossible Remember that the 'payload' is not just the humans, supplies and their life support systems within the ship, but also the entire ship itself, including its frame, engines, the huge fuel tanks it carries to hold the fuel, power generators and their fuel (you cannot rely on solar beyond about Mars) etc, etc, etc!

Yes, I was being deliberately optimistic on fuel : payload ratio in order to forestall the objections of any naysayers.

3) The ship (even disregarding the fuel) would be absolutely huge, as it would have to carry sufficient number of people to assure reproduction without degeneration for many generations of travelling time.

Not a real objection. I think we already know any ship that claims to carry a colony of 40,000 (as in Civ2) would be non-trivial to build.

4) Although you mentioned using it, you forgot to use the acceleration triangle. Using the simplified constant acceleration assumption, we have to double the travelling time to about 1700 years.

I mentioned it yes. I also realised that teh best way to forestall the naysayers would be to assume that the acceleration/deceleration periods take a trivial amount of time, and that the ship coasts at its top speed of 0.5% c for nearly all of the travel time.

5) Within 1700 years, there would be a very high probability of an accident happening on the ship that would be lethal to the entire crew in the hostile environment of space. The Mir space station almost crumbled within 20 years of its creation and it certainly had numerous close calls as well as less serious accidents. Simply put - man-made things do not last long enough to survive the journey.

Agreed. But let's not give the naysayers anything to bite into. I was simply giving the most wildly optimistic engineering limits, and still showing that the travel times are non-trivial.

6) Even disregarding all of the above, there is an overwhelming likelihood that the mission would fail as a result of tension within the crew. It is hard to keep interpersonal relations brilliant for 1700 years in confined space!

Yeah, sex with your crewmates can get a bit stale are the first few hundred years

7) As has been pointed out Alpha Centauri is unlikely to have any hospitable planets.

On the other hand, we do not know what kind of technology will be discovered in the future that may depend on physical laws that we do not yet understand. Breaking 'c' might not be possible, but there may be ways to cheat (think wormholes, or possibly other as yet undiscovered physical phenonema)!

As I said upthread, any AC mission will have to assume some kind of transportation technology other than rockets, even really good rockets.

[lajzar]

I just plugged the stats for a typical modern rocket - 500 isp and 95% fuel by mass. Assuming the thrust time is a trivial fraction of total travel time, we can expect to arrive in about 200,000 years

[Roman]

Originally posted by lajzar
That estimate is from various pundits involved in the Traveller SF RPG. Given that more than one of these people is a qualified rocket scientist in his own right, I am inclined to believe that group. Of course, we are still nowhere near controlled fusion as you so rightly point out.

You missed my point. What I was trying to say is that fusion engines might have an ISP of 50,000 theoretically, but like with every engine you never get 100% efficiency...

[lajzar]

ISP statistics take that efficiency factor into account.

Edited to add: My sources give varying ISP factors for modern rockets depending on whether they are in atmosphere or vacuum. The efficiency (and hence listed ISP) increases in atmosphere, as they have something to push against there. Of course, atmosphere also limits the top speed; it's a double edged sword.

[Leland]

Since Alpha Centauri ending appears to be patently silly, how about plagiarizing the Matrix and making the creation of a human level AI the top goal? It could plausibly happen within the next 50 or 100 years, it would be a logical ending to the game about human history (from science fiction we know that the first thing any artificial intelligence does is to try eradicate its creators... ) and it's an effort that might be modelled in the game as building research centers and studying new technologies.

[okblacke]

Originally posted by Leland
Since Alpha Centauri ending appears to be patently silly, how about plagiarizing the Matrix and making the creation of a human level AI the top goal? It could plausibly happen within the next 50 or 100 years

No, it couldn't.

Even if Moore's Law wasn't petering out.

We don't understand intelligence. The social "sciences" are the weakest and least likely to yield usable results for engineering. In desperation, current AI solutions tend to "brute force" their way toward correctness, so that we're not really any closer to modelling human-like intelligence, and we're pretty damn poor at faking it.

I think it's probably more likely that physicists will discover some means for faster-than-light travel and ways around that pesky second law of thermodynamics. And, uh, that we'll master gravitational fields.

Of course, that's just my opinion. I could be wrong.

[ok]

[DarkCloud]

Plotinus

Darkcloud, as lajzar points out, you are underestimating what would be involved in really going to another star system.

Actually, I am not.
With the progression of technology, the development of faster than light travel is currently on the horizon. When enough atoms have been smashed in devices such as the Superhadron Collider and the CERN laboratory we will eventually be able to develop enough negative density materials to be able to hold open 'mini-wormholes' long enough to pass data through... and once that is done, we may quickly discover ways to widen them and send humans through them.

And there are other ways to send humans through space at FasterThanLight speeds: supermagnets for one... superstring manipulation for another, etc.

And they're just out there, waiting to be developed

[DarkCloud]

Now as to the question of whether or not we will reach Alpha C by 2050- the answer, I will agree- is probably no. But it is possible by the year 2100 due to advances in nanotechnology and in physics and in the observation of the universe due to instruments such as the Hubble Space Telescope.

[lajzar]

Ah, but you are proposing radical new technologies. As I have now (repeatedly) said, we cannot reach AC with any form of rocket technology, at least not within 10 natural human lifespans.

However, I did also note (repeatedly) that the AC mission would be possible with radical new technologies, none of which were ever hinted at in any civ game yet released.

Basically the AC victory needs serious revamping. Either a renaming to Mars colony ship, or else a redesigned tech tree that includes futuristic propulsion technologies.

And of course, introducing wild future technologies has its own drawbacks. Many people have expressed a dislike for having a futuristic tech tree in the main game, as it would distract the game designers from making the historical aspect fully rounded.

[Plotinus]

[Darkcloud] I hate to be a wet blanket, and I don't want to sound like some Victorian scientist proclaiming that heavier than air flight is a fantasy, but something tells me there's a rather big gap from smashing atoms and sending data down a mini-wormhole in a lab to sending *objects* light years across space. A century ago no-one would have imagined the Internet, with all this information flying across the world at lightning speed; but I'd like to see you try to fax yourself to Tokyo. Similarly, no matter how many atoms you send down an accelaration tube and no matter how many data you send from one end of the lab to the other, I think to say that in a century we'll be ready to send human beings through holes in space is to stretch the "science" part of "science fiction" to the limits of meaning.

Even if it *were* possible, of course, it wouldn't happen - can you imagine how much it would cost? It was expensive enough getting to the Moon. I agree that the ending of the game should change to setting up a Mars base - although I don't believe they would change it, since after all they're not likely to rename SMAC to fit it!

[alva]

Who says money will still be around?

[okblacke]

Originally posted by Plotinus
A century ago no-one would have imagined the Internet, with all this information flying across the world at lightning speed; but I'd like to see you try to fax yourself to Tokyo.

We can xerox our asses and fax them to Tokyo.

Hey, we can combine two fantasies: Create artificial intelligence copies of ourselves and project those through wormholes. We'll conquer space without actually leaving Earth. Without even knowing it for quite some time.

As I said earlier, the ship may as well launch to Bananaland.

As for there being money in the future, we know there will have to be money, because money makes the world go 'round, and if the earth stopped spinning it would burst into flames. QED.

[ok]

[lajzar]

As I said earlier, the ship may as well launch to Bananaland.

And we may as well rename "bronze working" to "materials technology one". It has the same game effect. But it makes a world of difference in believability and game atmosphere.