A list of patentable features of the algorithm would be right at the top of my list as well. If you can also show lack of existing patents covering any aspects of your code that would be good too.

Yeah, just leave off the OSX part on the end for me, lol. Oh, well, and then there was the PDP-11C and the VIC20 before the C64... ;)

Eh, yeah, well, we can only discuss things within the context of our own knowledge and experiences, that's true. I'm not entirely convinced that we have 'no idea' though. I think in terms of knowing what things are likely to be physically possible we're in a lot better shape than the people of 1000 years ago. I'm reminded of Isaac Asimov's famous essay where he talks about there being a HUGE difference between virtually no data and having a lot of data but not all the answers. Ancient man believed the world was flat. Indeed this was a logic belief which conformed with the available data, but it was of course a horribly inaccurate estimate of the shape of the Earth. 17th Century people OTOH knew the dimensions and general shape of the Earth, but still were unaware of its exact shape, considering it to be a sphere. While still not perfectly accurate their estimate is good enough that for the most part it is still used today even though we know that the Earth is in fact 0.3% oblate. Likewise NASA does not normally perform relativistic mechanical calculations for celestial navigation, 17th Century knowledge of mechanics suffices for this purpose. Clearly the knowledge of the 17th Century, while incomplete in many respects was good enough to irrefutably declare that the Earth was round, and to calculate the trajectories of the objects in the Solar System to great accuracy.

Likewise our understanding of things like basic conservation laws, causality, and thus the absolute limitations on travel to the stars. These things are not simply theories we've cooked up. They are reinforced by a vast interlocking array of observations. To for instance posit the actual existence of a reactionless drive or some form of FTL would be as if some 18th Century navigator had stumbled upon a whole new continent in the midst of the Atlantic ocean, there simply wasn't any unknown territory with the room to fit it into anymore.

Clearly you can always just say "well, you haven't looked in the right place, your viewpoint is limited by current understanding" etc. but what would you say to someone who showed you a map with Atlantis in the middle of ocean? It just can't be fitted with what we know, and we've seen too much to discount it, Atlantis just doesn't exist. It can't. FTL and etc things likewise.

So, that means we have to do it "the hard way". Will that never ever happen? I just posit that the hard way is too uneconomical to be at all common. I don't claim it is literally impossible. Contrariwise it seems likely it is possible to some degree, but I question if it can really happen enough to matter.

Well, sure, I agree, it is hard to be certain what is and isn't going to be possible in an engineering sense. You certainly cannot say with absolute certainty what the capabilities of a specific mission mass budget will be centuries down the road. There are questions though, blind optimism is not advised. First of all we have yet to witness any sort of complex nano-technology in action. While clearly it is possible to do things similar to what living organisms do IMHO there must be some fairly significant barriers to going much further than that, otherwise we'd having life forms with such capabilities already. Nor is it at all certain that such small and thus delicate and vulnerable structures could survive for long in the high radiation environment prevailing during a high velocity interstellar voyage (or even just floating around in the interstellar environment for that matter). 'starwisp' type vehicles are at best highly speculative. Possible? Maybe, but nobody has suggested a framework under which such technology would work.

I've THOUGHT about a lot things. Obviously extrapolation is reasonable, OTOH plenty of engineers and such will tell you that this level of miniaturization probably won't work. I suspect the truth is somewhere in between. Many of the things it is so easy for a sci-fi author to write up like it is plausible will turn out to be pipe dreams, but many things will turn out to be possible. The question then is will the real utility of a bunch of these low-mass craft really be great enough to do a whole lot? Only time will tell. I think the loss rate could be very high and then you're sort of back to "it takes a lot of energy" again, just for slightly different reasons. If you coupled that with "these sorts of spacecraft are pretty limited" then where are you?

Its an interesting question at least.

Sure, never is a long time, but we also don't need to come even close to postulating never. Lets suppose it is difficult and expensive enough to travel between the stars that actual colonization is effectively a losing proposition. You might even be able to accomplish it now and then, but its not often attempted, rarely succeeds, and thus for every given instance of an inhabited planet the probability of founding even one colony is less than one. Under this assumption civilizations don't 'spread', so they will only come into contact by proximity.

Secondly we then look out at the sheer vastness of the Universe. If intelligent life isn't SUPER common, and doesn't last for millions of years, then the chances of 2 civilizations being nearby in time and space rapidly approaches zero. In the whole Universe will it never happen? Probably it will, but the chances that WE are one of that handful are very low.

I think that the fundamental stumbling block that I run into all the time with these sorts of discussions is that the human mind is simply not capable of appreciating the sheer scale of the Universe in both time and space. We see a Universe vastly full of 'stuff', but space is vast beyond all human imagining, and time is long beyond all human imagining. Unless intelligent life is either extremely common or extremely facile at both crossing these unimaginably vast reaches of space and enduring across vast cosmological ages of time then every such spark is almost sure to be unique and alone. If the Universe in its lifetime holds 10 trillion civilizations then we have virtually no hope of ever meeting even one other.

I would just say on the first point that every single organism we have ever observed, including humans, spends all the energy it can get hold of on growth and reproduction in some sense. There's NEVER 'spare' energy. Were there the vast quantities of spare energy that would be required for interstellar travel that would imply that said society has either A) limited itself in terms of growth, which IMHO implies it probably wouldn't be interested in exploration, a fundamentally growth-linked behavior; or B) is limited by some OTHER constraint.

Possibility B brings us to the second set of points you bring up. If a society was so advanced that it could do things like harness all the energy of its star, it seems hardly likely that possibility B would be a factor (IE at that level of technology you can simply synthesize matter from energy or harvest it from your star etc).

As for 'super technological wonders' like exploding stars... A) you have to posit some mechanism for this sort of thing. Its all well and good to say that is what would happen, but without either evidence or at least a theory as to how this would be done it is just a dead-end for any discussion, you might as well just say "fairies did it" or something. B) where are all these stars? Surely if a civilization can engineer entire star systems then its impact on the visible matter in the galaxy would soon be impossible to miss. Certainly if this sort of thing has happened much at all there would be whole interstellar civilizations of beings munching on stars. I can only assume one of two things is true, either this sort of thing is impossible (and indeed I cannot imagine any actual technological way to 'take apart' a star) or intelligent life is VERY rare in the Universe, rare enough that we can't pick out its signature from natural phenomena. Either of these alternatives tends to validate the original premise, that we're unlikely to ever meet another species.

Ask what question? I can ask "is some hypothetical alien civilization allocating energy to its individuals in such-and-such a way" until I'm blue in the face, there's no answer forthcoming at this time unless someone here can demonstrate that they are in contact with actual space-faring aliens... Thus we have to work from what we know. In fact I justified my assertion that no one individual would have access to excessive amounts of energy. We can debate this point of course but it wasn't the main point of the original discussion.

You can of course simply make your own assumptions, which is exactly what your points A and B ARE, simply unjustified assumptions. You would strengthen these assertions with some logical arguments as to why they are warranted. IMHO B can be dismissed. While it is likely that we will find methods of travel that are MOST energy efficient we already know the uttermost theoretical limits on minimum energy, which are actually the ones I quoted, 450 pWh/metric ton at 0.1C (and in fact this number has been demonstrated to be low by an order of magnitude). In order to achieve a lower energy cost the laws of nature must be such that the Universe as we know it could not exist. I understand that for people without a good understanding of modern physics and cosmology this sort of statement is always disputed, but its like saying after Magellan circumnavigated the globe that we could still discover that the Earth is flat, that ship has sailed, we positively know better.

As for your point A... ALL we can work with is what we know of societies ultimately. You can of course simply state "well, its alien, no argument from experience means anything" but that just means there's no discussion to be had AT ALL. I mean, fine, aliens are alien, nothing we know applies to them, we can all pack up and go home now. Instead what I've tried to do is both argue from analogy with human societies and to look at what makes human societies necessarily as they are. I've pointed out that one of the hallmarks of human society is economically rational behaviour. Humans aren't ALWAYS rational, not even at the level of entire societies, but they are pretty well bounded within limits. When a society becomes TOO economically irrational it simply cannot support itself anymore, necessary functions cease to be carried out, anomy results. Given the large investment needed to achieve even limited interstellar flight it seems reasonable that it would require some degree of stability to achieve. Economic rationality thus seems like a reasonable hypothesis, and its hard to make any sort of economic argument for interstellar flight.

As for the point that single individual (who in human society are often not rational actors) would have unfettered access to the vast energy required for an interstellar mission, the argument is similar. A society filled with irrational individuals, each one free to deploy terajoules of power as they see fit doesn't sound to me like it would last very long. Would human civilization last very long if every individual had the equivalent of an arsenal capable of sterilizing the surface of the Earth? I really doubt it. We're scared that someone might get a nuke or make a super germ. Any really advanced civilization will PERFORCE have integrated consensual decision making to a very high degree, and it will almost surely have to be quite rational.

In fact this is the real ultimate conclusion that the blogger in the original story has to come to, that advanced civilizations must be very rational, very conservative too. The alternative is what? Societies that stagger forward to advanced technology for a decade or a century and fling a few random objects out into the void before they go kaboom? If so then I think his conclusion, that we're never likely to meet them, is justified. Either way it seems justified. The likelyhood seems low IMHO. I've explained that line of reasoning, as did the original story. You're free to object, but I think the discussion won't move forward until you're willing to really examine your own assertions and weigh them against other possibilities.

Energy, or rather work, is the ultimate 'currency'. That's what you always pay for things in, or that is that's what their cost is, which you never pay less than.

Of course your star could be about to 'go kaboom' but that is going to be a once in many billions of years event for any given species, as are other such cosmic events. So we hardly need imagine it comes up often enough to matter.

The whole POINT of the debate of course is that some people can't imagine why you wouldn't do something, but lets consider some sort of analogy. Now and then human socities do something very expensive for what seems like little really logical reason. However this is extremely rare, and never rises to very high level of total society output (for instance we only expend 2% of our wealth on war today). The one single example I can even muster of a large organized social project of no explicit utility which required double digit fractions of economic output were the last few pyramids built by the Egyptians, and they only pulled of really three huge ones and about 10 other somewhat smaller examples, all within the span of a few decades. But imagine the US spending 2 TRILLION $ a year for decades on some project for which the economic return is zero and the necessity doesn't exist. It is just far-fetched.

Depends on how determined you are to go fast. A nuclear/vasimir type of design, or other advanced fission designs, could deliver constant acceleration for long periods of time with quite high specific impulse at quite useful thrust levels. You could QUITE easily get to Pluto in a year with a fairly large spacecraft. From there we can extrapolate perhaps 10 year flight times. Clearly change the aim/focus of your telescope is quite difficult, but I could see launching such a mission to study an Earth-like world around a relatively nearby system. You could in theory resolve quite a lot of detail and it would be well-worth the mission to make a close study of such a system. It may be 50 years yet before we really have deployed the relevant technology and had enough practice with it, but we could do it. If you are OK with a 40 year mission profile then nuclear propulsion isn't needed.

Ah, right, I'm unworthy to participate in your high level of erudite debate. Pfffffffft! Give me a break bozo. If you want to have a discussion it helps to be civil, but since you're not up to that...

In any case:

Its fine to ask these kinds of questions, but surely in a society which we might conceive to be something like known human ones since when does any one individual have at their disposal routinely vast quantites of energy far beyond what they need? We can point out some individuals today who are given some authority to direct the use of many resources, but they certainly aren't in absolute control. Any society which routinely put petawatts of energy in the hands of single decision makers with no obligations and constraints placed on them would not last long! If you had actually followed my entire argument you might have noted that these points have been touched on already. RATIONAL societies survive long-term, and what's rational about expending vast amounts of energy in dubiously useful ways? Our own history doesn't show much in the way of examples of this happening.

Yes, but you still fail to appreciate just what you can do with 1.316 × 10^14 kWh (and realistically of course considerably more) BESIDES accelerate 40 tons to 0.1C. 40 tons is basically an object the size of a large bus. Such an object would be a very limited probe for the cost, lacking any means of slowing down at the other end just what exactly would you hope to gain by expending a year's worth of our current power output?

There is a QUALITATIVE difference between using oil to commute 100km and traversing 50 trillion Kilometers of space in a reasonable timeframe. The cost of the former is tiny and the alternate uses of the required energy aren't particularly compelling as a result. The cost of the later is huge, equal to everything humanity today can do in a year. Even in some future with vast energy availability (and you'll quickly run into problems harvesting even a small fraction of the Sun's total output) there's no denying what that energy is capable of. Its a simple matter of trade-offs.

Sounds right. Of course I can do that math myself, but why bother? Clearly Wikipedia is a pit of inaccurate arithmetic... ;)

700 AU is of course a LONG distance, but only a tiny fraction of the way to the nearest star. We could probably today without any major new tech build a probe that could reach that distance in a decade or two, maybe less. It would be a tiny fraction of the cost of even a high speed flyby probe of a nearby systems.

Cost?

I think people really fail to appreciate the HUGE costs involved. Energy is the ultimate currency. Its hard to see the need.

I got my numbers from various sources. The power requirements for 0.1 C travel came from the Wikipedia article on interstellar travel (but the math cited there appeared to be correct). The power output of the human race can also be found on Wikipedia, but is also found in IEA reports, so I would have to assume that number is at least roughly correct (I used the 2008 numbers).

In any case, I'm not sure which number you are correcting, but it sounds like you are saying the energy required to accelerate a mass to 0.1 C is 10x more than I stated. Even if its 10x easier than I stated (or we generate 10x more power today) it just means we could send 400 tons to Alpha Centauri in around 50 years vs 40 tons. Neither is even close to an adequate mass for a manned mission of such duration, though perhaps it would suffice for a flyby mission at 0.1C. I wonder if such a mission would actually learn much that we can't learn FAR cheaper by just building a huge telescope or 20. The costs are so vast it would seem like we could build an instrument to sit out at the gravitational lensing point of the Sun far more cheaply, or some other equally large scale project.

Its a discussion thread, if it is 'spoiled' by there being more than one side to the discussion then all of /. is utterly pointless, just go talk to yourself! lol.

As for who says, energy says. It would take a monster amount of energy (read above) to travel to another star system. Surely such vast quantities of energy are far beyond what any individual would ever need. Thus it seems unlikely to me that one or a few people would ever possess by themselves the means and authority to deploy such large resources to such a project. If an entire civilization (or a large part of it) is both so impractical and so empowered that it would do such a thing then isn't it vastly more likely such a civilization would simply do something stupid and wipe itself out due to its own impracticality? That's the whole nut of the "scale beyond a few individuals" because if the whole society is insane then yes indeed they might dream of interstellar travel, but they're not going to be in a position to achieve it.