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lajzar
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Japan
Jun 2003
time: 14:34
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quote:
Originally posted by Plotinus
Darkcloud, as lajzar points out, you are underestimating what would be involved in really going to another star system.
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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 
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Roman
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Bratislava, Slovakia
Sep 2000
time: 05:34
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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)!
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lajzar
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Japan
Jun 2003
time: 14:34
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quote:
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).
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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.
quote:
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!
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Yes, I was being deliberately optimistic on fuel : payload ratio in order to forestall the objections of any naysayers.
quote:
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.
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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.
quote:
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.
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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.
quote:
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.
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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.
quote:
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!
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Yeah, sex with your crewmates can get a bit stale are the first few hundred years  
quote:
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.
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lajzar
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Japan
Jun 2003
time: 14:34
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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.
Last edited by lajzar on 02-03-2004 at 03:22
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Plotinus
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[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!
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okblacke
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quote:
Originally posted by lajzar
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. |
Actually, I believe you were the one to ask if you were the only one who noticed it. I think one other person chimed in.
In other words, it only makes a "world of difference" to you and one other guy. Well, let's say a small percentage.
Civ is, of course, a game of abstractions. The symbolic importance of the Alpha Centauri launch is that Man has finally broken the bonds that have tied him to where Fate and God cast him.
Mars doesn't do that nearly as strongly.
And, okay, Bananaland would sort of take game atmosphere in an unforseen direction.
But I don't think it needs to be changed until it's perceived as a problem by a larger portion of the audience. Until then, it has tradition and SMAC on its side.
[ok]
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okblacke
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quote:
Originally posted by Oncle Boris
Seriously though, I heard that in 30-40 years scientists will be able to plant chips in the brain to increase its capabilities. |
Ask yourself how many predictions made between 1960 and 1970 for the year 2000 came true.
quote:
What I guess is that if it works, it might allow us to quicly transcend over the current limitations of our intelligence and progress really fast in discovering new laws of physics. |
We don't use the capacities of our brains at present. Not to repeat the old canard about only using 10% of our brain (because it's not true) but our problem isn't one of capacity, more of tradition, ambition and understanding.
Our brains don't seem to ever get full: the presence of total recall in humans demonstrates that we haven't touched whatever structural limits exist; the existence of various savant abilities demonstrate, again, that structure is not the limiting factor in speed or capacity to comprehend.
I submit that gaining the technological ability to successfully create neural implants would reveal enough about the brain that we wouldn't need to.
And the big problems there are cultural. Tradition. Superstition. Politics. Especially politics. Education seems clearly to be going backwards. (Or stalled at the bottom.)
[ok]
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PresidentMarcos
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Ehh...
Instead of making planetary colonies on Alpha Centauri, build ORBITAL COLONIES.
Far superior to planetary ones, as construction is much easier in zero-G conditions and asteroid mining can provide resources.
Besides, you can build around 10-15 orbital colonies for the price of one AC spacecraft. As for a sci-fi victory condition, I have no clue whatsoever.
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Leland
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There's obviously demand for more realistic victory conditions, so I give you: "You Beat Other Players" victory condition... with 3d animation of an exhausted gamer doing a victory dance in front of his computer?
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Plotinus
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[Leland] My God, can you imagine the other game possibilities... "Sire, we've received reports that your girlfriend is trying to talk to you about the fact that you promised to do the shopping today but you've just been playing this silly game. Shall we tell her - (a) Just one more turn, I'm about to build Copernicus' Observatory; (b) Of course dear, I apologise for my neglectful behaviour; (c) Silence woman! Or I shall unleash my 4-tank army on you."
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Jarred
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I bet you 250 gold that we can research the proper techs on the tree to reach it before you make it to Pluto.
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Silpy
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The USA's European Colony
Sep 2002
time: 05:34
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What about an AI race? For each civ to attempt to be the first to create a true AI- , now that, I feel would be a fitting end for Civ IV (the birth of human civilisation to the birth of AI civilisation) Though I am unsure of the way this could be put into the game.
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Max Sinister
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Yes, I like the idea too. You could call it "scientific victory": Intelligence recreates itself. Didn't we have that in another thread?
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Drachasor
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Hmm, isn't the Alpha Centauri project basically the science victory though? I suppose they could add another, but it seems redundent.
Maybe give it more of a militaristic edge, so you can have sort of a "scientific/military victory" as opposed to a "scientific/peaceful-victory". The big rush for A.I. would be a bit like the A.C. project then (lots of buildings and lots of devotion to finish), but when you are done, you get quite superior units. Bombers that are half the cost of current Bombers and more effective. Troops that are half cost and cost no war-weariness (no live people fighting), and the like.
The downside is that you can't upgrade any of your current units to the A.I. units, you have to build from scratch. That fact should allow people neck and neck to stay neck and neck, which somehow seems desirable. Winning the A.I. war then would require a lot of espionage, both to defend your projects and sabatoge theirs, so that you have enough of an advantage to build an A.I army and mop the floor with them.
Ehh, it's an idea anyhow. I don't think we need another Peaceful Scientific Victory though.
-Drachasor
P.S. And yes, A.I. will actually not be as focused on war as I made out, but it was the main new avenue for Civ that I saw for it.
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01-03-2004 18:22
QED.
versus a year number..
Attachment: 
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