KSK

Well frankly it's better to base an argument on a technically correct definition than a bizarrely wrong one as you did. With regard to your second point - what do you think a living organism is if not 'a complex self sustaining system of chemical reactions with an external source of energy.' You're not talking about an external system that the earliest organisms needed to evolve - you're talking about the organisms themselves. And besides - you're still missing (or wilfully ignoring) the point that that first complex system - call it an ecosystem, call it an organism, call it 'a complex self-sustaining system of chemical reactions (with an external source of energy)' arose from an environment where no such thing previously existed. Absolute nonsense. That randomly evolved organism needs to be just as capable of reliably producing specific complex systems as a deliberately engineered von-Neumann machine. They wouldn't last long if they didn't. I already defined physical as 'something not forbidden by the laws of physics'. I've already conceded that von-Neumann machines may turn out to be impractical - but there's a significant diffference between technically impractical and physically impossible. Anyway - I suggest we agree to disagree on this one. I'm clearly not convincing you, you are most definitely not convincing me, so I'm going to quit before this gets acrimonious and the thread gets locked. Thanks for the debate. Edit. Apologies for the mixed up quote formatting.

And I've repeatedly argued that the notion that self-replication requires a complex ecosystem is wrong. On Earth at least, self replicating systems arose, by chance, in an abiotic environment. We have no idea exactly what environment was required to start that process off but we can say that no complex ecosystem was required because until self-replicating systems arose, by definition there were no living organisms around to create that ecosystem. (You can argue about what constitutes 'life' but the ability to replicate falls into all of them) Like I said, it all had to start from somewhere. Given that self-replicating systems can and have arise by chance, without a supporting ecosystem, I don't see how you can argue that there are any fundamental physical laws that would prevent the construction of a von-Neumann machine, that is a system capable of moving from one suitable abiotic environment to another and establishing a self sustaining, self replicating colony within each of those environments. I say 'suitable abiotic environment' because, as previously stated, I believe that a practical von-Neumann machine will need some chemical diversity to work with - a self-replicating system constructed entirely from one element, including carbon, seems vanishingly unlikely. In short, I think von-Neumann machines are an engineering problem and I will readily concede that they are an extremely difficult engineering problem that we're unlikely to be solving any time soon. However, I don't believe that they are an unphysical problem, in other words, there are no physical laws that rule them out entirely.

Yes - but there are other organisms (e.g. the cyanobacteria that I keep banging on about) that don't need the resources released by the decomposers.

Fine - it's a web. I referred to a chain because it's conceptually simpler and the distinction between the two was irrelevant for my argument. In any case, presumably your decomposers are decomposing other organisms? In which case they are not at the bottom since they're feeding on other organisms.

What? We've got some back-to-front definitions here. An ecosystem is the sum of the different living organisms in a given area, their interactions with each other and the interactions with their environment. Living organisms and the environment itself are the primary systems, an ecosystem is an emergent system created by the interactions between those primary systems. Ecosystems can be large, small, or even nested. A coral reef would qualify as an ecosystem - existing within the much larger ecosystem provided by the Earth as a whole. Take a living organism out of its ecosystem and it may or may not survive. Organisms at the bottom of the food chain will probably survive quite handily - see my earlier comment about cyanobacteria on Mars, unless their new environment is utterly inimical.They survive precisely because they're at the bottom of the food chain and so by definition are not dependent on other organisms for survival. Organisms further up the food chain do (again by definition) depend on other organisms for survival (at a very basic level, they eat them) and so, taken out of their ecosystem, will not survive. For each of your points: 1. Correct - but only in the sense that individual organisms arose through random processes and then aggregated into ecosystems. 2. Not entirely correct. A coral reef is an ecosystem. A lichen is an ecosystem (albeit a relatively simple one) comprising a fungus, an algae and/or a cyanobacteria. Both are quite capable of self-replication. 3. No organism (or von Neumann machine) is entirely self contained. To do anything meaningful such as move or replicate, they're going to need energy and materials from their environment. However, as discussed above, some organisms are far more self contained than others.

Right - so how did that other, similar life arise? At some point you need to have abiogenesis, that is, living (thus replicating) systems arising from non replicating precursors. Now it might be that Earth is the only planet where this has happened. Given the size of the Universe, I think this is spectacularly unlikely but nevertheless, Earth might have provided that one special environment. But for our purposes, that doesn't matter. Earth provides the one key example that we need which demonstrates that replicating systems can arise from non replicating systems. It might be improbably unlikely, we might never figure out a way of doing it synthetically (aka build a von Neumann machine). However, it is quite obviously not physically impossible - else we wouldn't be here arguing about it.

Well in that case you're asking for the impossible because we have exactly one example to work with and that verifiably has been affected by life for on the Earth (being as it is the Earth) by a significant degree. If that's your requirement for proof, we're wasting our time here. Myself and SomeGuy123 have specifically pointed out an organism that can subsist on simple inorganic materials and would be capable of subsisting on those materials regardless of where they're found and any other prevailing environmental conditions. A complex system is not required and I would be quite prepared to bet that we could take a suitable terrestrial cyanobacteria to Mars and that it would flourish. Your 'chicken-and-egg' premise that replication doesn't occur naturally except where there is a complex system supporting it is, I think, wrong. Taking the only system we know as an example; once a replicating system arises, it necessarily changes its environment to make it more favourable for other such systems to arise. For very simple replicators, I can imagine 'dead' (whatever that means in this context) replicators releasing parts of themselves into the environment thus providing a source of more refined materials for other replicating systems to start with. Once we get to a replicator that uses phosphorus in some way (for metabolism, storing information or whatever) then we have something that is capable of dramatically accelerating the phosphorus cycle, increasing the availability of this vital nutrient for other replicators. Complexity of environment and complexity of replicators increase in lockstep. Logically though, at some point there has to be a transition point from 'environment without a replicator' to 'environment with a replicator'. By definition that environment arose naturally because there was no other way it could have arisen. Unless of course we're straying into sci-fi or religion and assume that the Earth was specially set up to support life by an outside agency, but I think that's outside the scope of our discussion.

It's a small point but not one I've seen posted before. Please could we have a consistent ordering on thread tags? As an example, I've applied three tags to my fanfic: 'writing' (duh ), 'backstory' and 'space program history'. I've noticed that any two of those tags can appear at any given time, when I would really prefer to have 'writing' and 'backstory' displayed permanently, with the third or subsequent ones hidden for readers to dig down into if the first two catch their interest.

Yes. Or I can for cyanobacteria, aka blue-green algae, which I suspect are what SomeGuy123 had in mind. I have no reason to doubt what SomeGuy123 is saying about culturing E. coli but I would have thought they would need a source of nitrogen and phosphorus as a bare minimum over sugar, air and trace metals. Cyanobacteria can live just about anywhere. From the Wikipedia page: "Cyanobacteria can be found in almost every terrestrial and aquatic habitat—oceans, fresh water, damp soil, temporarily moistened rocks in deserts, bare rock and soil, and even Antarctic rocks. They can occur as planktonic cells or form phototrophic biofilms. They are found in almost every endolithic ecosystem.[9] A few are endosymbionts in lichens, plants, various protists, or sponges and provide energy for the host. Some live in the fur of sloths, providing a form of camouflage.[10]" They can fix atmospheric CO2 as a carbon source. They can fix atmospheric N2 as a nitrogen source. I presume they require some source of water (no matter how marginal) as a source of oxygen and hydrogen. On top of that they'll need a source of phosphorus (which is a limiting nutrient for most organisms) and then probably sulphur and other trace elements. These are all available from the environment - there is no need to postulate a vastly more complicated ecoystem for cyanobacteria to replicate within. In fact, I would imagine (without any citations to back this up) that cyanobacteria were the amongst the very first organisms responsible for taking 'a bare lump of sea and rock, girt all about with clouds' and transforming that into the 'vastly more complex machine' that you refer to. The same would be true, I think, of a von Neumann machine. It will require an appropriate environment - probably a carbonaceous chondrite or something with enough chemical diversity to provide the necessary raw materials for replication. It will not require a complex ecosystem finely-tuned to support that replication.

General Order Zero - supplementary. Nobody gets left behind, not even redsuits.

I remember when I started on that third part - figured it might be a bit unexpected after the rest of the story up till then! Glad it's a case of 'more reading required' rather than 'WTF - no.' and it should make a bit more sense in a few chapters. Hopefully. Maybe. Thalamask - I hope so! I like to think the first eight chapters are a good taster but you've still got some of my favourite parts to go! I better keep with the decrufting program though....

It's a good idea - I liked the part about blank planets until you go there 'for real'. Kerbal Construction Time had a good implementation (it probably still does - haven't played for a while) - you could start your tests from the launchpad or from any sphere of influence. Testing cost money too, to provide a bit of balance.

KSS Mort's Pride. KSS Gravitational Anomaly. KSS We Built a Bigger Boat. I could go on. Anyhow that bad boy is going be a bit like the Saturn V going up. "Bill - did we just launch or did we just push Kerbin out of the way?"

Ahh, Krasniyy Ivan - the old kerbal's rocket. And remember Comrade - MechIVAN is watching you...

I don't know. Loveable fools they might be, but they're not short of raw courage either. (Sure - I'll strap myself to this stack of SRB's - what could go wrong!) If push came to shove, I think Kerbfleet could surprise everyone - probably including Kerbfleet. Anyhow - loving the new story, especially Sarge. We need moar Sarge!

I have the utmost respect for your aunt and anyone else who works in the organ donation and transplant field and I think it's disgusting that we live in a world where people even need to think that they might have to be frightened about being pronounced 'dead' as you describe. With that said, I still think it's a mistake to conflate 'the medical community' with 'the organ donation and transplant' community. I expect I could speak to a doctor, to a medical researcher at a university or to a CEO of a pharma company (all arguably members of the medical community) and they would all give me different reasons why cellular memory research has been overlooked and probably not because of its potential impact on organ transplants. Regarding ethical and moral questions, I personally think that cellular memory is sufficiently unlikely that its ethical and moral implications don't need to be seriously addressed. However, if I am wrong then I entirely take your point and in fact, recipients worrying about accepting organs from criminals would be the least of our problems. Sadly, I think it's far more likely that people would be concerned about accepting organs from gay/black/male/female/old/yellow/pick-your-prejudice people. One question to finish off. Are there any documented cases of people losing memories after having organs (or parts of organs) removed? That would certainly lend some credence to the cellular memory idea.

With respect, I disagree. In general, organ donation and the ethics surrounding donation are taken extremely seriously. If transplant memories were a thing, I have no doubt that they would be taken into account as well. Saying that 'the medical community' - which is hardly a homogenous body in the first place - is suppressing this research because of a perceived fear to the transplant business (whatever that might be) is a pretty serious allegation. I read the linked article and found it less than convincing although I'm not sure how much of that was due to it being a layman's article about a reputable hypothesis or a deliberately woolly article about an implausible hypothesis. To its credit though, it did offer alternative explanations which I found far more convincing, particularly the notion that some of the changes ascribed to 'cellular memory' could have been a side-effect of immunosuppressive drugs. I would also add that any sort of transplant is going to be a pretty big physiological upheaval and I wouldn't be remotely surprised if that led to the observed changes in dietary preferences. As a very loose analogy, bizarre food cravings are often associated with pregnancy.

I would have thought that the good old-fashioned way of making babies would be adequate for that, possibly backed up with some kind of assisted reproductive technology. No need for full on cloning.

I'm curious but short of 'lots of humans' being 'almost complete extinction', why would this be a good thing? Presumably whatever caused such a dramatic population crash wouldn't exactly be a conducive environment for suddenly throwing a lot more humans into, whether by cloning or more traditional methods.

They're for interstellar vandals and egotists. Because nothing says 'civilized species here' like taking a chunk of space and converting it into myriad copies of the same thing. I hope that by the time we have the technical prowess to build such things, that we have the societal prowess not to.

Ahh - fair enough - thanks for the quick response. Still not keen on the 'Big Brother is watching you' motif but at least it's private. Would prefer to have it as an additional drop-down menu alongside Messages and Notifications but appreciate that might require too much tinkering with the forum setup (or not be possible at all).

Hi, Just a quick request for user profiles - is it possible to remove the 'warning points' box, or at least make it a little less obvious. I see no real reason to have it on ones profile anyway - infractions and warnings should be a private matter between you and the forum moderators - but having it up front and centre in eyecatching black on white feels a little bit insulting to be honest, even if the the number of warning points is a big fat zero. Cheers. KSK.

So they're in good company then? Seriously - no need to be quite as derogatory about other fan works, particularly fan fiction (yes I have a personal bias here). It might not be as overtly impressive as a hardware mod but people put a lot of time and effort into their writing too. If you've already skimmed through some of the fanfic on offer and decided it's not for you then fair enough. Otherwise - give it a go sometime. You might be pleasantly surprised, not least at the lack of shipping. Going back to your post, I'm not sure why the fanworks stuff was compressed into two forums anyway, although I'm sure there were reasons. Myself, I'd favour more subdivisions rather than fewer, to help people find what they're looking for without wading through piles of stuff they aren't as interested in. Anyhow, this is going off-topic so I'll stop here.

Great stuff! Glad you're liking it and thanks for dropping by to comment. Where are you up to so far?

Nice! Great dialogue that made me laugh out loud in places - I particularly liked the 'theorizing' at the end and: "“He really does. It’s kind of an aesthetic now, to be honest. Also, can I have your chair, Bill?” No tips on formatting though I'm afraid, although centering the top line only seems to work for me. *shrug*