I first apologize for being an obstacle to intellectual progress.
I then pose the question:
Is it impossible for Venus to have harboured some form of life (sentient or not) involved in a carbon cycle not unlike ours, hundreds of billion years ago, except (or perhaps similarly...) due to one of the "Great Filter" probability barriers, the life on the planet eventually produced a runaway greenhouse effect, which leads to the current state of Venus today (and over hundreds of millions of years, wiping all obvious traces of life)?
Even now, we might be less than 50 years from independent colonies, if lower costs for space launch finally "take off" with Musk.
This implies that if there is some common reason (e.g. a physics experiment with unexpected outcome) that exterminates budding civilizations, it ought to have already happened (and we were lucky) -- or it is something big enough to blast a whole solar system.
Edit: It would be interesting with percentage chance evaluation of the possibility that the Shuttle project doomed humanity to extinction...?
Surely whatever improbability would be diminished because of this?
Since we don't see galaxy-spanning, highly advanced civilizations, there seems to be some combination of factors that prevents planet-bound dirt from turning into them. If those factors are primarily after our stage of development between dirt and galactic civilization, that's Very Bad News, because we shouldn't expect to get extraordinarily lucky. If those factors are primarily before our stage of development, that's reasonably good news, because we've already made it past the hard part.
Seeing bacteria isn't as bad as seeing the ruins of a civilization just past our stage of development. But it does move the probability-mass forward more than if we just found dirt.
My view is that it's likely/possible the universe is has quite a lot of life. However, since all evidence suggests the universe had a beginning, between abiogenesis, evolution, and the universe/galaxy/planet being in a state hospitable to life, it might always take a very long time to get the state we're in now, just as it did on this planet. It's quite possible that there are billions of planets with life in some stage of evolution, but few of them are significantly more advanced than our planet's life. Even if there are a smaller number of super-advanced civilisations, they may only have been broadcasting for a few hundred thousand years, and we may not be in range of that, or pointing our antennae at the right place to pick up the very weak signals. Even if they have discovered FTL travel, it would conceivably still take an extremely long time for them to visit every planet in the universe. Even if they have visited Earth in our historically documented timeline, they may not have been interested enough in what they saw to stop by and have a chat. Worse, if they have discovered FTL, they're probably not using radio broadcasts any more.
But that doesn't mean that life is uncommon, or even that there isn't some intergalactic federation of civilisations, just that any given civilisation being significant enough to notice or be noticed happens rarely. I would be far more worried about extra-terrestrials being hostile than non-existent (see Stephen Hawking's views on the matter).
Really, most of these sort of arguments feel quite similar to a bunch of humans sitting around a hundred thousand years ago, discussing with their tribe that they are probably the only humans on the planet, since no other more advanced cultures have communicated with them yet. Even though they haven't discovered any efficient means of transport to actually explore the Earth yet...
$ curl http://www.nickbostrom.com/extraterrestrial.pdf | pdftotext - -
Also, pdftotext is part of poppler in Arch and poppler-utils in Debian.
Thanks anyway, though.
I'm really paranoid about loading unfamiliar websites up (I've got a version of Chrome with js and plugins disabled that I use for random links), and pdfs are still a bit of a concern as an attack vector. It looks like this viewtext.org will come in handy.
- - -
Example using this PDF:
Clean, light, and doesn't require a GA login.
All this reported by ANSA.
PD: it was in a conference in La Sapienza, in Rome, hardly a remote and/or obscure university/place.
The author's evidence for that bold headline claim was earlier reporting on the issue as the speculation built up.
"Whatever Curiosity has found, it is not evidence for life on Mars. It can't be. Curiosity is not designed to look for life. Grotzinger has stated this himself. In a Nasa video about the mission, he says, 'Curiosity is not a life detection mission. We're not actually looking for life; we don't have the ability to detect life if it was there.'
"Following up the internet speculation, Jeffrey Kluger of Time talked to Nasa's Jet Propulsion Laboratory spokesperson Guy Webster and was told, 'It won't be earthshaking, but it will be interesting.'"
Organic molecules (molecules containing carbon) are commonplace in many lifeless places around the Solar system, so this is hardly surprising. It is moderately interesting, but certainly not earthshaking, as previously reported.
AFTER EDIT: Replying to the first reply kindly posted to my comment,
I'm not arguing whether Curiosity has found evidence for life on Mars or not but I would like to point out a logical fallacy in the cited argument; in particular, the statement "device X wasn't designed to do Y" does not imply "device X can't do Y".
I take the statement made by the NASA planners at face value for a simple reason. While the Curiosity rover, with its cameras, would surely be able to detect Martian megafauna, if there were such a thing, for example a Martian elephant, I trust the statement that Curiosity is incapable of providing unambiguous evidence of microorganisms on Mars. I cited the Guardian article in my first posting of this comment. The issue of detecting life, or not, was surely discussed by the NASA mission planners, who included astute exobiologists. The mission profile of Curiosity does not include a task of detecting life on Mars, and the instruments on Curiosity are not reliable for distinguishing organic molecules made by living microorganisms from organic molecules made by purely physical processes. Whatever Curiosity detects with its molecular analysis instruments, it cannot be taken as evidence for life on Mars. That is the statement of the article, based on interviews with people knowledgeable about the planning of the mission, and that is a credible statement, given the amount of thought the mission planners must have devoted to this issue.
The USSR discovered water on the moon about 40 years ago in 1976 - http://www.technologyreview.com/view/428030/soviet-moon-land... They also had landers on Venus in the 70s http://nssdc.gsfc.nasa.gov/planetary/venera.html Why did NASA announce in 2009 as if it's unexpected and novel that there's water on the moon? http://www.nasa.gov/mission_pages/LCROSS/main/prelim_water_r...
From http://en.wikipedia.org/wiki/13_Things_That_Dont_Make_Sense#... ?
In this case, however, since the scientists know what they'd need to "prove" life, they can state that Curiosity doesn't have enough sensor capability to gather such evidence. Rather than stating that Curiosity was not designed to detect life, it would be more appropriate to state that Curiosity is incapable of providing rigorous proof of life.
Now, back to the evidence. Stating that what Curiosity has found is not evidence, may be taken at face value only if we narrow the definition of "whatever Curiosity has found" to the information capable of being gathered and returned, as opposed to the sources of the exhibits under observation (which may or may not have a biological origin, or may or may not be a precursor to biologic functions). A thin metaphysical/epistemological distinction to be sure, but one that is relevant because when we need to trust our senses, we need to know our sensor limits, and when we need to trust remote sensors, extra-terrestrial remoteness is as remote as it gets, and its hard limits cannot be easily overcome once deployed.
That would be a pretty conclusive proof of live even though Curiosity wasn't designed to work in that way.
Curiosity could certainly detect certain kinds of life... but not the types of life astrobiologists are guessing might exist near the surface. Curiosity definitely can detect active chemical processes for which there would be few if any non-biological explanations... but after so many false positives in the past the science community has decided that alone would not be definitive proof.
Curiosity was not built to detect life, but it can. However scientific conservatism would likely mean any “yes” result would be interpreted as a ”maybe.”
One can always hope...
The reason why methane would be exciting is that it is broken down by UV radiation, so there must be some persistent source of it on the planet for a sustained presence.
Edit: Here are similar stories from PC Magazine and Mashable, which was apparently the original source of all of these articles:
Sorry for the pedantry.
"how does this jive with" - About 257,000 results
"how does this jibe with" - About 234,000 results
"how does this gibe with" - About 6,490 results
Also, Curiosity is quite capable of unambiguously detecting life on Mars, the question is just a matter of how likely it would be. Curiosity can detect a wide array of organic compounds, and if a sufficient quantity of the right variety of compounds were detected it could be near incontrovertible proof of life. For example, if you fed a pile of fine wood shavings into Curiosity's SAM instrument you would be able to look at the data and go "yup, this is absolutely, definitely, wood, it couldn't be anything else".
The difficulty is that realistically the amount of organic matter from some life form that is sampled by Curiosity could be fairly small and very difficult for the rover to get any useful data out of. That's why Curiosity was not designed as a "life detection mission", which would require other instruments. However, that doesn't mean Curiosity is incapable of detecting life, just that it would likely have to get fairly lucky to do so, and most of the evidence it would gather would likely be fairly circumstantial rather than definitive.
This is all rather speculative though as there has been no information provided on Curiosity's new findings, merely more speculation from people who don't know the findings (in this case the manager of JPL).
If Curiosity founds "celulose", that is a very complex ~20000 atom molecules, with the atoms arranged in a very special scheme, then it is almost almost almost sure that it was created by some kind of life, because we don't know any non-biological process that can make it.
The main problem is that there is no distinction between organic and biological molecules, so you can't make a sensor that distinguishes them.
The very simple molecules (formic acid) are expected to be found even in places without life. The intermediate molecules (some sugars, aminoacids, even some nucleotides) are more rare, but not unexpected. The big complex molecules are unexpected, so after discarding everything else, the conclusion would be that in that place there is something living.
A similar problem is "How many grains of rice is a lot of rice?": One is not enough, one million is enough, but there is no a clear border. There is not a clear border between organic and biological molecules; the question is "Is the probability that a molecule like this was created by a life form greater than the probability that a molecule like this was created by an inorganic process?"
For a given molecule, life tends to strongly prefer either the left-handed or right-handed version.
Curiosity's gas chromatograph can tell them apart. If it finds a strong handedness preference for several chemicals, then Mars almost certainly has life.
Partly this is because we still need to know about the mineralogy of Mars, there is a ton we don't know. Improving on that knowledge will mean that we are all that much more able to target the regions of Mars that are more likely to harbor or have harbored life. And then we can send a "life detection" class mission.
However, such missions aren't easy. Consider a few of the challenges. In order to determine the composition of a rock you really don't care about the extreme minority constituents of that rock. If you can figure out what the elemental composition of the rock is within, say, 1% that can be a good day. However, if you want to determine whether or not a sample of dirt contains living or formerly living microbes then you are talking about a teeny, tiny fraction of a fraction of a percent of the material. Which means that you don't just need to break down the material into its major parts, you need to figure out how to focus in your studies to just that small bit of biological material. Which could mean extremely high magnification microscopes, for example, though that has a throughput problem. Or it could mean making use of various experiments to prove the existence of running metabolic activities within living organisms, such as using radiologically tagged nutrients, for example. But these sorts of things are pretty much a crap-shoot, and wouldn't help if the biological samples are no longer living.
Also, a NASA life detection mission requires much higher standards of clean-room assembly and pre-launch sterilization, which add expense and complication to the mission.
Keep in mind that for unmanned "life detection" missions a spacecraft would not just be constructed in a clean-room but all of its components (as well as the whole vehicle) would be extensively sterilized (at 112 deg. C for about 30 hours, for example). Additionally, the vehicle would be extensively swabbed throughout assembly to search for any amount of biological contamination.
However, more than likely the focus will not be on an unmanned life detection mission but rather on a sample return mission (which would be optimized to try to find samples containing life) or on a manned mission (which would also likely entail sample return). In either case there would be a considerable amount of research resources available to study any samples of Martian life, should it be found, and bring to bear instruments or tests which would unambiguously show it to be of a different origin to Earth life.
Imagine if you were only allowed to purchase $100 of equipment - it could either be a digital camera that can take pictures of fossils and definitively prove life exists on Mars once and for all, which is less likely than, a piece of equipment that detects the presence of methane in the atmosphere. (more likely but less definitive proof).
The way NASA communicates to the public makes it tough. If a troupe of green martians wearing tophats and kilts started doing the "Lord of the Dance" routine in front of the rover, NASA would announce "We are still awaiting test results, but we believe that the Curiosity rover may have discovered organic materials that resemble felt that resembles something that could potentially be a hat."
More seriously, adding extra components to a mission means many more man-hours designing, testing and vetting the extra functionality, and also adds a boatload of extra weight, which makes the entire thing massively more risky and expensive (especially with the rover's at-the-time-unproven landing mechanism). There's no real need to send everything at once, especially if a lot of what you're sending could be ruled out as entirely unnecessary depending on the results of other tests you're carrying out.
So, finding some organic molecules in Mars is totally expected. On the other hand, finding a any proof of life in Mars would be amazing, but as far as I understand this "report" is only an uniformed speculation.
In biology carbon is the backbone molecule for all life/biological chemistry, although there are theories that on other planets/ecosystems other similar chemicals, such as silicon or germanium (both able to form 4 bonds, like carbon - same column of the periodic table) may be able to fill the same role.
From the scientists perspective discovering 'organic molecules' is important because basically when you get down to the nuts and bolts of what carbon molecules are, the point is that on a planet with an environment such as mars', without 'biology' as an underlying mechanism for the generation of these molecules, there shouldn't be any, I.e. they will all get degraded by the environment without some process churning them out.
That doesn't mean it's the only way that they can be made, just a theory that we have for their source.
The presence of methane (organic and usually biological in origin) in the Martian atmosphere has long been suspected of being persistent (ir should otherwise escape/be broken down) because of renewal due to biological activity however that is far from clear and more likely scenarios put the gas escaping from geological processes under the surface as the cause.
The long and short is thus that the discovery of organic molecules may be a tantalising clue to the presence of biological processes, either now or at some time in the past, however there would likely remain many alternative hypotheses to rule out and it would be (extremely) unlikely that any announcement could point to the existence of a form of 'life' on mars due to the equipment they have available.
As to what is a biological molecule, well, that's a harder question. In a somewhat tautological way I'd probably say that's something coming from a biological organism.
DNA is a biological molecule - a molecule used more or less exclusively in biology and not spontaneously occurring outside the context of life.
We do know that organic molecules with non-biological origins do exist on other planets and even on asteroids. Titan has large quantities of organic compounds on it's surface that have non-biological origins, for example. It is believed that at one time Mars had a much thicker atmosphere and active geology which may have lead to the formation of organic compounds.
Methane on Titan would be a better example, and I actually initially used methane - but most people have experience with methane in the context of biology, too.
Charles Elachi (http://www.nasa.gov/about/highlights/elachi_biography.html) is an eminent scientist in his own right (follow the link to see) and you can bet he's very well-informed about MSL, which is JPL's biggest mission right now. This is because Charles has been running JPL ever since MSL was in the planning stage. His job would include briefing all interested parties about the progress of the mission and its instruments for about 8 years now.
In no sense is Charles Elachi "just like every other armchair scientist".
Besides this side show (I work at JPL so it's bothersome to read mischaracterizations of Charles), I agree with you that this story has been shifted beyond what it actually means. If I read you right, that's what caused you to comment. "Organic" has been changed from its chemistry meaning ("containing carbon") to its lay meaning ("coming from something living"). And "perhaps" has been left out completely.
Charles is a careful speaker and a veteran at communicating results to the public. This is why his statement contains a specific disclaimer ("not biological"). You have to give the article credit for getting this right.
And he said, in fact, that that was what they found, but that it's still a "perhaps" because they have to check the data very very thoroughly. Read the news, and get your informations right.
Please stop trolling all over the thread, thanks :)
NASA is the agency that made a big prime time press conference for their "arsenic DNA" discovery not so long ago, which proved to be BS (and not well researched at that).
Ultimately, the weak link is the guy at the conference, not the site where it's reported.
It's amazingly interesting and well argued. In short, the author says first that any sufficiently advanced civilization will at one point send self-replicating probes that will eventually colonize all of the galaxy and even universe. And it takes only one match to light a fire, and this is important--that is, for a sufficiently advanced planet, it would take only one rebel, one mad scientist, to set the colonization, by robots, of every habitable body in motion.
Assuming the above is true, then why do we not see any sign of these probes? It follows that there must be a Great Filter that prevented them from ever being created. Things that qualify as such a filter are not plenty, and include the original formation of life and the transition from procaryotic to eucaryotic (taking a couple billion years).
Thus if we find life so easily formed on Mars or anywhere else (especially eucaryotic cells), we can assume these past events are not really Great Filters. Then, the only reason we haven't found a single probe is that any sufficiently advanced civilization destroys itself before it ever gets to that point. If it's not nuclear weapons, then there must exist technologies that are sure on our path to discovery while at the same time guaranteeing our extinction--again, think in terms of things that only need one outlier to use it in a way that compromises the existence of all on Earth for good.
So he concludes that we must pray that we never find life anywhere else, because it would in turn give us hope (but not assure us) that there might exist no Great Filter ahead of us, and the Great Filter was indeed in our conception as life--thus we are the one single unfathomably lucky planet to ever have harbored life. If nothing potentially impedes our expansion, we will be the one sending probes and expanding to everywhere.
Adding my own expansion on this, I believe it's extremely unlikely that there is some irrevocably cataclysmical tech to be discovered before ever we are able to send self-replicating probes--ones who can mine the raw materials needed for unbounded expansion.
I don't think we're that far from that point, and taking from our own anecdotal existence since it's the only one there is, even if we do annihilate ourselves before sending them out by chance, other civilizations might not have done so, if they existed. Thus indeed the only tech that would assure a Great Filter is the self-replicating technology itself. And that is a strong point--the author seems to ignore the fact that these probes wouldn't really be the expansion of humanity, it would be the expansion of drones. And what might the precursor techs for such a replicating machine look like? If superior AI is needed at any rate, we could think that the tech leading to sure extinction is indeed robots who decimate us humans. And since they would do this as early as chance would afford it, the robots eliminating us would be as dumb as possible--thus we can assume they would be incapable of advancing technology on their own; or of coordinating an event like launching themselves into space, and thus would never leave Earth. In this scenario, we can assume every civilization that ever got a shot in going to space ended up extinct, their planet ridden with dumb self-replicating robots who can never launch themselves into space.
Since self-replicating robots are the hypothesis of the author's argument, then indeed it makes sense that every potential civilization either never reached this tech (the Great Filter is in life's conception, or otherwise somehow denies the existence of self-replicating robots), or it must absolutely reach it, in order to colonize space, but in doing so it declares it's extinction.
So, like the author, I also hope that we never find life elsewhere, that we might put our tiny hopes in thriving as a race, the only one that ever existed.
: Just an hour ago, I would have jumped with joy if this NASA announcement was indeed confirming life.
And, for a moment, let's suppose your thought experiment is true, and there's an alien probe somewhere in our solar system. Would you be surprised we haven't found it yet? There're an awful lot of places left to look.
1. I was wondering if we could apply an anthropic type of argument here? We are having this argument at this time and place because we predate the colonization by self-replicating bots / other end-of-world scenarios. Multiverse version: any time we're having this discussion, we are on the surviving branch predating self-replicating bot colonization that renders the planet unlivable. I realize this type of argument can be extended to reach absurd conclusions, but nonetheless it's an entertaining thought.
2. What is life? What is civilization? What are their goals? Why do we assume a society of relatively independent individuals? Is it even a sustainable model for a post-human level civilization? Aren't we anthropomorphizing aliens a bit too much? What if a civilization either dies out at human-level stage or necessarily reaches a mental unification point and all its further activity is inward focused? I think we're on the first stages of self-awareness compared to rocks and jellyfish, imagine the level of self-awareness experienced by a far more advanced civilization. Would it necessarily be resource and space-greedy and try to colonize the galaxy? At least it's not immediately obvious to me why it would.
3. Another point is, what scales are we looking for? Doesn't our scale essentially depend on the planet / star system we evolved in, and the scale at which original life started? What basic building blocks / resources does alien life use? Maybe they rely on physical resources we haven't yet explored (dark matter, etc). Essentially I'm agreeing with the people saying "we don't know what we're looking for".
And there is no need to assume that it is so slow. We have already designed technologies to send probes to stars much, much faster than Voyager 1. Here is one. Put a bunch of solar panels on Mercury, and use the power to shine a laser into space. That can push on a light sail, pushing the probe outwards at something like 1% of the speed of light. Then as it nears its star, let the sail fly away, shine the laser again, and have its reflected light brake the probe.
With this level of technology, which may be feasible for us in just a few hundred years, the colonization of an entire galaxy can be reduced to tens of millions of years.
If technological life is out there in our galaxy, in the blink of cosmic time finding evidence of it will not be a search for a needle in a haystack - it will be closer to finding a piece of straw in a haystack.
"I will return to this scenario shortly, but first I shall say a few words about another theoretical possibility: that the extraterrestrials are out there, in abundance but hidden from our view. I think this is unlikely, because if extraterrestrials do exist in any numbers, it’s reasonable to think at least one species would have already expanded throughout the galaxy, or beyond. Yet we have met no one."
Sorry mate, but it's not reasonable to think that at all. The galaxy is colossal. We have exactly zilch insight into how even a two-star civilization might work, and the kind of problems it would have - and he's saying it's reasonable to assume the existence of a civilization with dozens of thousands, or hundreds of thousands, of millions of stars?
It's possible, maybe, but it's not reasonable, and it doesn't disprove the idea that we simply haven't looked deeply enough for ET yet. As Jill Tarter of the SETI Institute once remarked , it's like asking if there are any fish in the ocean, filling a cup with ocean water, and upon discovering that it has no fish in it, you conclude that all the world's oceans don't, either.
In short, we haven't done the experiment yet - we may as well refrain from making conclusions. Our galaxy could house a million times the diversity of species in Star Trek, Star Wars, Battlestar Galactica and Mass Effect combined, but it may take a while to find evidence of any of that.
That said, I'd probably enjoy the novel.
Top quality propulsion can shrink the time to 50 million years, which means somebody can colonize the galaxy faster than dinosaurs can evolve into talking monkeys.
So there has been plenty of time for robotic probes to colonize the galaxy. So where are they?
In fact, using current technology, we actually could build a "self-replicating probe" loaded with algae and other photosynthetic single-celled organisms. So we really can't rule out ourselves as the evidence we're looking for. We might even be evidence that such probes usually malfunction.
I like that.
AFAIK, mammals existed during the dinosaur era. But they occupied a tiny ecological niche and were physically tiny. They survived the asteroid hit because they were tiny.
The absence of dinos enabled them to eventually occupy niches occupied by dinos.
They're bacteria and they already colonized Earth.
My hunch is that it's true: that when we get better at detecting it, we'll discover bacteria/viruses/spores of various kinds all over the place (including Mars and other solar system locales).
I heard recently that if the earth was 3 times larger, the most advanced chemical rocket would not have the energy density to leave the atmosphere.
Scientists now know that with out a Jupiter, the asteroid belt might not form in such a way to deliver 'water' and protect us from large comets roaming the galaxy.
Even now it may not be possible to leave our solar system without a significantly different understanding of physics. Voyager is just no leaving our solar system, and it will take decades for it to actually leave the effect of our sun. Today if we launched a craft it probably would get just about as far as Voyager in just about the same amount of time, but maybe our power source could power a more efficient version for a decade longer, getting us just a bit further than voyager will, but still no where near Alpha Centauri.
For us to explore the depths of space, it would need to be much easier and cheaper than it is today.
For it to even be plausible a DIY Scientist as you suggest would need to create energy density so powerful, it would be hard to imagine a world where that sort of thing is not regulated.
For us to study sub atomic physics, we have a structure that is 20 miles in length, this is not the research of... a DIY community.
Today we argue about Iran getting enriched plutonium for nuclear research, when some think they want to build a bomb and others think they want to build a power plant. I really can't imagine a neighbor of mine being able to ... take that step without raising some alarms.
Your mad scientist would have to be on a far off island/ comet/ moonbase with all of the resources and man power required without interference from others, but still have access to raw materials.
I am just not sure we will find other worlds in humanity's lifetime.
We may be able to colonize mars and a few other large bodies in our solar system, but leaving it is a different story.
well unless he, or his supporters, are also granted dictatorial control over a significant portion of the planet.
And there is also the possibility of having intelligent civilizations never reaching the space age for one reason or another.
We have only ONE specie on Earth among billions which reached this point, it is not like we have much of a sample to make any rule.
All this is just assumptions based on very small data pool. Meaningless.
I am also not too sure the maths adds up either.
Lets assume that this "spread everywhere" civilisation does exist, and it fortuitously started evolving just after the Big Bang, and neatly at the "centre" of the universe (i.e. somewhere that is not next door to us, nor the furthest point possible from us)
Lets also assume it took them roughly 4Bn years to evolve to the Promethean level (age of the Earth) and so have been spreading for past 10 BN years.
And (yet) another assumption - they spread uniformly outwards, travelling at speed of light (!) but taking a recharge period to, I don't know, consume the resources of a planet, build a few houses, before spreading again.
So, with a observable bubble of 46 bn light years, and 10^^23 stars in it, I think the following calculation works
* there are 10^^23 stars , spread evenly over 46 bn light year diameter bubble
* they atarted their migration to us (to everywhere really) 10bn years ago
* between the "them" and us there should therefore be a even distribution over 23 bn light years or ~ 10^^23 - 10^^9 = 10^^14 stars.
* given a "pause" of 100 years at each star system and light speed travel in between that is still 23 bn years plus (100 x 10^^14) 10^^16 years or a ridiculous number that I have probably got wrong but is clearly older than the age of the universe many times over.
I know this can be tweaked any which way, but if we are looking at the pan-dispersal approach, even simple lower bound cases make it highly unlikely that a civilisation spreading enormously fast and comprehensicvely throughout the universe will still "never" get here for any value of "never"
That's the mistake. Its an extension of cultural / religious / philosophical values of the European colonial era. Not politically correct in this era or likely any point in the future.
Its the "star wars" effect applied to SETI. The "star wars" effect is we used to have emperors and knights in shining armor and mage/paladin wannabe types and castles and long choreographed sword fights so I'm sure the future will have them too. However good a hollywood movie plot, that's not realistic.
Repeating Earth's 1492 is dramatically less likely than ... a gray goo accident. Look for one of those. Or evidence of an unfortunate accident involving using black holes/singularities as a power source.
Also, when thinking about this, i don't think we should discount the possibility that we have already discovered and merged with other forms of life, especially during explosive growth periods over previously uncharted territory. Maybe some forms of life we know of today were actually independent in origin.
But i definitely like this kind of intelligent design by self angle more than any other.
Using a transport infrastructure whose effects can be seen across the galaxy.
A theory of advanced races who have different sensibilities misses the point. What matters are the ones that have a growth and expansion sensibility. The first one of them to arise will conquer the galaxy.
However, what everyone else in this thread has been saying, is that his conclusion (that no life exists elsewhere) is wrong because there are number of other possible explanations as to why we don't see evidence of this civilization. A quick summary of some of those arguments:
1. The expansion that Bostrom assumes is inevitable is actually physically impossible at the scale he describes.
2. It is possible that we are actually a by product of that expansion (DNA being the 'self-replicating' robot).
3. The expansion is happening, but hasn't reached us yet.
4. No other civilization has reached such an advanced stage yet (it is entirely possible that our 4.5 billion years was an extremely and uniquely fast time for evolution to intelligent life)
5. Super-intelligent civilizations come to conclusions that expansion is not a productive or useful undertaking.
While it is possible that life doesn't exist elsewhere (or at least intelligent life), it is by no means the natural conclusion to Bostrom's hypothesis.
I favor this possibility. Fledgling expansionists cannot know if they are wards of conservationists who have spent the past billion years developing spying technology and culling weapons. On a game theoretic basis, every sensible fledgling expanionist, even the first one in the universe, should reasonably act as if a living god is judging them.
We already know of at least one catastrophe we are rebuilding from, there's also no reason to think we weren't already rebuilding from earlier (possibly much larger) catastrophes.
Following this, there's nothing to say that we haven't already had some major effect on our surroundings (intentional or not) in some previous, possibly more complex or larger-scale growth. Our influence on our surroundings could be huge. Lack of life or anything that seems anomalous in our immediate vicinity could be our own doing. A seeming lack of evidence for this might be explained by scale, or the nature of the catastrophe, or (if it was intentional) by design.
We have great difficulties to find foreign planets. We barely know what's beyond Pluto. Heck, we probably have a couple of surprises waiting for us in the solar system.
One cannot expect us to be able to detect alien probes, operating with engines and communication capabilities beyond our understanding, probably only few meters wide (if not much smaller!) and operating somewhere near our star, probes we don't even attempt to detect in the first place.
Plus there is a bias toward colonization. I agree that an advanced civilization, except if it becomes extremely xenophobic, would probably want to explore the universe, but colonize? If you have the technology, it's possible you don't need to spread physically that much.
Just speculations of my own, of course.
We have cultural fantasies and biases that will be hard to break free (or do we want it?), and the possibility of fully reliving those as we please will be a Great Temptation as the writer puts it.
Still I think it's short-sighted in that the people who can be as powerful in real life as everyone else can in the virtual will take advantage of it and control the masses with infinite happiness. So I don't think it's ultimately a good point to stand for the Great Filter.
I would wager, attempted mischief, that words themselves are the self-replicating machine, to the Universe..
Think about it. These very characters, here on this page .. motivate the pro-creation of yet more, and so much the human organism is designed exclusively for the propagation and 'existence' of these words, that eventually, to the Universe, it must look like each letter is but a sperm, off to meet some fertile substance designed to fuse another font of near endless replication, reproduction, duplication, consumption ..
How about hydrocarbon fuels? They don't need one outlier. They seem to have chemistry and physics resulting in an economic trap for t heir use.
2. Hydrocarbons are a temporary religious dogma, not a trap. There are collosal amounts of thorium waiting to be tapped when the energy religion is reformed.
A bit of hyperbole there?
As if our opinions change the chemistry of a planet none of us have ever been to.
Guy Webster, a spokesman for NASA’s Jet Propulsion Laboratory in Pasadena, Calif., which operates Curiosity, said the findings would be “interesting” rather than “earthshaking.”
According to the article posted he said "perhaps" they found organic molecules. Or am I reading it wrong?
Can anybody verify if this news is true? Or its from a trust worthy source?