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Old 10th November 2017, 08:57 PM   #1
Fudbucker
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Dark Forest Theory

Briefly, dark forest theory is a theory that the universe is a dark forest where it's kill or be killed. The optimum strategy is to hide and hunt, silently taking out anything that might be a threat to you, gobbling up anything that might increase your chances of survival. There's no avoiding infinite chains of suspicion, so the wisest choice, if you meet someone, is to assume hostility on their part. Infant civs like us, who leak like a sieve in the EM spectrum are quickly gobbled up, which is one reason that explains the fermi paradox: most civs hide, suspicious of every other possible civ. The ones that don't hide already got poached.

The problem with this line of thought is that we're not like that. We haven't cloaked ourselves. We broadcast welcome signals. And even if we're a rarity, if there's a lot of civs in the galaxy, there are a bound to be a few more like us. Given enough civs, two friendly ones will eventually find themselves near each other and make contact and cooperate. Wouldn't cooperation lead to faster tech progress than mutual distrust? And if, by some fluky chance, there are a cluster of friendly naive cooperative civs all right next to each other, might they become extremely powerful? Powerful enough to swat down the lone hunter-killers and establish some rules to live by in the forest?

Thoughts?

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Old 10th November 2017, 09:54 PM   #2
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I think life is commonplace, but reaching multi-cellular sentience and intelligence is extremely rare, so a so-called "intelligent" civilization like ours is probably alone right now in this galaxy. And space is so vast that by the time another civilization hears from us, we'll be gone. I don't think we need to worry about getting gobbled up.
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Old 10th November 2017, 10:59 PM   #3
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It seems like Dark Forest Theory vastly overestimates our EM presence, and gets rather more romantically extreme from there.
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Old 10th November 2017, 11:11 PM   #4
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Originally Posted by theprestige View Post
It seems like Dark Forest Theory vastly overestimates our EM presence, and gets rather more romantically extreme from there.
The inverse square law works to our benefit. Our EM leakage probably won't be noticed, but specifically beaming powerful messages to specific stars might not be the greatest idea.
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Old 11th November 2017, 12:57 AM   #5
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The Fermi Paradox is explained by habitual interstellar predation leading to self concealment of multiple advanced star-faring civilisations?

How was the information that concealment is the best policy acquired? Did one civilisation see a second one being "consumed" by a third?

This is all very difficult to visualise.
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Old 11th November 2017, 01:21 AM   #6
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Someone has been watching too much Star Trek, and over-thinking it.
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Old 11th November 2017, 01:56 AM   #7
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I think it's less Star Trek and more Three Body Problem, a nice sci-fi series by a Chinese author.

The basic flaw in the proposition is that life from one planet would be in competition with life from elsewhere.
But in competition for what?
Energy is basically free in the universe if you don't go too far from a star, and material is everywhere.
Given how hard it is to move through space, any invasion fleet would be massively outnumbered by the forces of the host system, technological superiority or not: the Aztecs could have crushed Cortez a dozen times but (for stupid reasons) chose not to.
Space is no Petri dish that life can extend exponentially into.
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Old 11th November 2017, 01:59 AM   #8
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Originally Posted by Fudbucker View Post
Briefly, dark forest theory is a theory that the universe is a dark forest where it's kill or be killed. The optimum strategy is to hide and hunt, silently taking out anything that might be a threat to you, gobbling up anything that might increase your chances of survival. There's no avoiding infinite chains of suspicion, so the wisest choice, if you meet someone, is to assume hostility on their part. Infant civs like us, who leak like a sieve in the EM spectrum are quickly gobbled up, which is one reason that explains the fermi paradox: most civs hide, suspicious of every other possible civ. The ones that don't hide already got poached.

The problem with this line of thought is that we're not like that. We haven't cloaked ourselves. We broadcast welcome signals. And even if we're a rarity, if there's a lot of civs in the galaxy, there are a bound to be a few more like us. Given enough civs, two friendly ones will eventually find themselves near each other and make contact and cooperate. Wouldn't cooperation lead to faster tech progress than mutual distrust? And if, by some fluky chance, there are a cluster of friendly naive cooperative civs all right next to each other, might they become extremely powerful? Powerful enough to swat down the lone hunter-killers and establish some rules to live by in the forest?

Thoughts?
Perhaps start reading some science fiction? Then you will at least get some entertainment out of these thought exercises?
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Old 11th November 2017, 07:16 AM   #9
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This is the plot of Greg Bear’s Duology, Forge of God/Anvil of Stars (1987)

The Earth is destroyed by robotic probes (Von Neumann machines) sent out in vast numbers to discover nascent technological civilizations that might pose a threat to the “planet killers”

A fraction of Earth’s population is saved by the “Benefactors”, who assist the children of the survivors in their quest for vengeance.

“The birds don’t sing in the forest when there are hawks about.”
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Old 11th November 2017, 08:22 AM   #10
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Old 11th November 2017, 10:09 AM   #11
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Originally Posted by The Great Zaganza View Post
I think it's less Star Trek and more Three Body Problem, a nice sci-fi series by a Chinese author.

The basic flaw in the proposition is that life from one planet would be in competition with life from elsewhere.
But in competition for what?
Energy is basically free in the universe if you don't go too far from a star, and material is everywhere.
Given how hard it is to move through space, any invasion fleet would be massively outnumbered by the forces of the host system, technological superiority or not: the Aztecs could have crushed Cortez a dozen times but (for stupid reasons) chose not to.
Space is no Petri dish that life can extend exponentially into.
That was a great series. Liu Cixin didn't address the objection I made: that clusters of rare cooperative civs would become immensely powerful. Is it a bad objection?

There are a finite number of habitable planets in the galaxy.

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Old 11th November 2017, 07:50 PM   #12
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Originally Posted by Fudbucker View Post
which is one reason that explains the fermi paradox
This was the concept in the books, Forge of God and Anvil of Stars. The first question you have to ask is whether there is a Fermi Paradox.

Scientists tended to assume that our sun was average. It isn't. Only 7.5% are G type stars like our sun. However, half of those are binaries. So, now we're down to 3.75%.

We don't actually know how common planets like our Earth might be. If our solar system is typical then there is a big problem. Venus is too small to support complex life and all the other solid planets, moons, and dwarf planets are smaller than Venus. There's nothing between Earth and Neptune, and of course, Neptune and the other gas giants are out of the question. But it's actually worse than that. Neptune is 17x the mass of Earth but even the mini-Neptunes at only 3x Earth mass are also too big.

So, we would apparently need planets at least as large as Earth and no bigger than maybe 2.5 Earth masses with an orbit from Earth to Mars. However, that probably isn't quite right. Earth is in all probability too small and also just outside the habitable zone. So, the actual requirements might be more like 1.5 - 2.5 Earth mass with an orbit farther out than Earth and no farther than Mars, probably between 1.1 and 1.5 AU. And the planet would need to have a fairly circular orbit. You might also need gas giants farther out to help prevent bombardment from asteroids and comets. One optimistic assumption was that there were billions of habitable planets in the galaxy. A realistic upper bound is probably 500,000.

There are more requirements to develop intelligent life and more still to develop an organism with general intelligence like humans. Do civilizations disappear? That notion provides fodder for the deluge of second-rate dystopic books and movies that seem to be popular these days (especially with preppers). However, I don't recall any that were based on science. Civilization near Earth cannot last more than 5 billion years since that is when the sun will go nova. Is interstellar travel possible? If not then there could already have been general intelligence that has vanished. Also, we cannot currently pick up radio signals from just anywhere in the galaxy. We would never hear a radio on the other side of the core even if they pointed an antenna directly at us.

What we can actually detect is out to a few thousand light years. So, we have a limited time frame for any civilization that gained radio capability within that time. For example, we know that there are no radio sources within 50 light years unless they are more recent than that. We couldn't detect a radio signal 1,000 light years away if they only started broadcasting 500 years ago; it wouldn't have reached us yet.

Then we have to deal with a couple of silly assumptions used to create the Fermi paradox. The first was that other stars would be colonized. The basic assumption was that it would only take 5-50 million years to colonize the whole galaxy. This assumption makes some sense if you believed that there were indeed billions of habitable planets. However, at 500,000 this is far more difficult. If evenly distributed then habitable planets are 4 light years apart. Let's assume that 1/1000th the speed of light is possible for colony ships. That would be 4,000 years average between colonies. Can a ship even be built that can operate reliably for that long? Could even a robotic probe be expected to be working 4,000 years later?

The second silly assumption was that civilizations would eventually create Dyson swarms and use a detectable fraction of a star's energy. These could perhaps be detectable even in other galaxies. However, there doesn't seem to be any evidence that Dyson swarms are practical or even feasible.

So, there could be 100 civilizations in the galaxy right now and we would have no way of detecting them. That isn't much of a paradox.
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Old 13th November 2017, 10:14 AM   #13
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There is probably no possible net gain from interstellar resource piracy.

A ship that could collect resources and return those resources to its origin, on a time scale of less than millennia, would have to be fueled by antimatter. And even with that, you need somewhere from thousands to billions of tons of it. Any other fuel, and the multipliers from the four required accelerations mean you'd be starting with something the size of a small moon to end up with a container ship's worth of loot coming back.

There's a problem with antimatter fuel, though. You know what's less resource-intensive to synthesize from scratch, via nuclear reactions if necessary, than antimatter? Absolutely anything. Your interstellar raid makes less sense than building a car that runs on shovelfuls of five-carat diamonds, then driving it to a grocery store 1,000 miles away, to steal or buy oatmeal. (All the same issues apply to peaceful interstellar trade of any material goods.)

Of course, there are many other possible mission parameters than a round-trip raid for material resources. Too many to address them all individually. But most of them have similar problems, or different ones that are comparably severe. If some civilization advanced enough to have already exploited a large fraction of their star's output goes looking for another star to chew on, they won't be looking for a relatively short-lived one like our sun. The Star Trek model of simply transplanting colonists onto planets that are habitable but uninhabited by intelligent species (perhaps because those species have been preemptively fumigated) would only be attractive to aliens dependent on living on a planet surface; that is, like ourselves, not adapted to surviving long-term in artificial space environments or able to directly exploit large portions of stellar outputs. But in that case, given that warp drives etc. are fiction, it's unlikely they could get here.

I'll grant the possibility that sending a doomsday Von Neumann weapon or Omega Virus or whatever is more practicable than actually raiding or colonizing. The theory then is that "they" might do it to us out of fear that we might do it to them. That would make sense if there were also some other benefit, some possible gain or some possible grievance, that would motivate either of us to do it. In that case, a Prisoners Dilemma situation might arise. But if fear they might do it first is the only reason, there's no Prisoner's Dilemma.

So, in the end, Fudbucker, I think your argument about cooperation is a valid and powerful one.
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Old 13th November 2017, 10:55 AM   #14
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Actually, the argument (as I've heard it) is a bit more nuanced than presented here, and has little to do with resource piracy. It's primarily about survival, and based on a few ideas.

1. Any species, by being the dominant life form on it's planet, will place it's own survival above that of other species. If a species didn't, it wouldn't survive.
2. The technological ability to travel from one star to another necessarily entails the ability to reach relativistic speeds...some significant fraction of the speed of light.
3. With relativistic speed comes the ability to completely sterilize a planet. The term is "R-bombing" or relativistic bombing. At speeds which are a significant percent of the speed of light, impact can give you almost a full matter-to-energy conversion. Even relatively "small" devices can cause enormous damage.
4. Also at relativistic speeds, it's hard to detect an object. By the time you detect it, whether by radar, visible light, gamma rays, whatever, it's already moved on from the detection spot (speed of light limit). Assuming any sort of maneuvering capability, that makes relativistic projectiles difficult to intercept reliably if they have any maneuvering capability. Not to mention that the plan must be to divert, unless one can be sure of complete vaporization. Fragmenting an object means a shotgun instead of a rifle.
5. The only way to determine whether an incoming object at those speeds is a weapon or a ship is if it starts to slow down.

So, the basic idea is that any species capable of interstellar travel necessarily is also capable of planetary ecocide (I suppose that's the best word? Destruction of the biome of a planet). So, what risk of genocide of your species is acceptable?

While it's not considered very likely...it's a bit more reasonable than this thread assumes. The idea is that this would have built up over time. Once the first contact "went bad", so to speak, the idea would spread. It would only take one paranoid race deciding to initiate a "first strike" mentality on any system/planet that could potentially destroy them. Now, how word of these destructions would spread I'm not sure on...don't know enough about the technical side to say if the impacts would generate any detectable signals at interstellar ranges.

But basically, it's not so much about competition for resources, as it is about minimizing risk of genocide. I first heard it as the "Central park" theory. You're wandering around Central park in the dark. You know there could be crazies and/or criminals around. You could try to find a street light, but that makes you more visible to anyone who would want to harm you. You could try to find a police officer, but that also entails calling out or moving around to look, increasing the chance of running into undesirables. You could use a flashlight, but that also draws attention to you. The safest option is likely to try and stay quiet, not draw attention to yourself, and try to find your way out. But in the real universe, there are no policemen, there are no streetlights, and there's no way out of the park.

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Old 13th November 2017, 11:48 AM   #15
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I liked the trilogy and thought it made a good case for its premise. I think the main idea is that of "chains of suspicion". Because of the vast distances between stars and the relatively slow speed of light, communication between species would be almost impossible (unless you were willing to wait years, decades, or centuries for replies).

And therein lies the problem. You have no idea if the aliens you just detected are friendly or not. If they are great. But if they are some kind of evil Hitler species, sending them a hello could doom the earth. Even if they were not an evil Hitler species, they don't know that we are not. So if you work out the game theory problem that underlies this, the upside is an exchange of knowledge after years and years of trying to find a mutual language and the downside is the destruction of your planet. The idea is that any rational species will attack any other life it detects before they themselves are detected and possibly destroyed. And to keep silent so you don't get detected in the first place. Thus the Fermi paradox.

Makes for good sci-fi but is the universe really like this? I'm not so sure it's that easy to kill planets though the books did posit several different ways. Maybe this idea keeps everyone quiet minus the actual planet killing.
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Old 13th November 2017, 12:06 PM   #16
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Originally Posted by theprestige View Post
It seems like Dark Forest Theory vastly overestimates our EM presence, and gets rather more romantically extreme from there.
I like this picture regarding our Em presence.
https://planetary.s3.amazonaws.com/a...broadcasts.jpg
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Old 13th November 2017, 12:10 PM   #17
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I often wondered what the aliens in Independence Day came here to take. The Mona Lisa? The Coca Cola recipe?

Seriously, with tech like theirs what might we have to offer? [/what others have said]
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Old 13th November 2017, 12:21 PM   #18
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There's a Voyager episode where the crew want the help of a much more advanced civilisation who have their own version of the prime directive which prevents them giving it, and they try to bribe them with a copy of a database containing all the Federation's literature.

I can see civilisations exchanging stories, music - anything that can be sent electronically. Physical objects, though, are unlikely for the reasons already discussed.
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Old 13th November 2017, 05:31 PM   #19
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Originally Posted by Myriad View Post
There is probably no possible net gain from interstellar resource piracy.
That’s true of the raw resources, but one thing that might make sense is using local resources to produce some very light weight and valuable finished product. What could be light weight and valuable enough? The end product of information processing.

Whether science, art, or something else, it could be created through local resources and beamed back to the original system via radio waves, which is certainly much cheaper than anti-matter power spacecraft, which I agree will never exist.

The return on investment of the original “raid” ship will be extremely long, but it depending on the value placed on the information returned it should pay for itself after some number of millennia.

ETA: Well, that’s what I get for not reading the thread, Pixel42 just made basically the same point.
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Old 14th November 2017, 12:06 AM   #20
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Originally Posted by barehl View Post
Venus is too small to support complex life and all the other solid planets, moons, and dwarf planets are smaller than Venus.
Wrong! Venus is pretty much identical in size to Earth. It's 95% of Earth's size and has 81.5% of Earth's mass.

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Old 14th November 2017, 01:28 AM   #21
Craig B
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Originally Posted by Hellbound View Post
Once the first contact "went bad", so to speak, the idea would spread.
By what means would the idea spread? The very thing any theory about this requires to explain is why ideas are not spreading. We do not receive any ideas via SETI. Your dog eat dog cosmos inhibits the spread of ideas, as you acknowledge. That is my problem with this scenario, as I have stated. You propose
Quote:
The safest option is likely to try and stay quiet, not draw attention to yourself, and try to find your way out. But in the real universe, there are no policemen, there are no streetlights, and there's no way out of the park.
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Old 14th November 2017, 01:59 AM   #22
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Originally Posted by Hellbound View Post
Actually, the argument (as I've heard it) is a bit more nuanced than presented here, and has little to do with resource piracy. It's primarily about survival, and based on a few ideas.

1. Any species, by being the dominant life form on it's planet, will place it's own survival above that of other species. If a species didn't, it wouldn't survive.
I don't think that follows. If the challenges to survival are not great in proportion to a species' ability to control it's environment, it can have many other priorities and yet still manage to survive.

In general each individual will have a survival instinct, as the genes for this will have been selected for, but that doesn't necessarily translate into valuing the survival of the species.

Still, I do find it likely that members of any species will tend to put more value on their own species than on other species.

Quote:
2. The technological ability to travel from one star to another necessarily entails the ability to reach relativistic speeds...some significant fraction of the speed of light.
We have another thread here where we've been discussing non-relativistic interstellar travel. The time scales are very long and there are some technological requirements (the ability to rebuild or repair all the components of your ship on your ship) but I personally find it not only plausible but perhaps more plausible than relativistic space travel, at least for any large scale ship.

Quote:
3. With relativistic speed comes the ability to completely sterilize a planet. The term is "R-bombing" or relativistic bombing. At speeds which are a significant percent of the speed of light, impact can give you almost a full matter-to-energy conversion. Even relatively "small" devices can cause enormous damage.
That makes sense if your species is localised on a planet. But if you have colonised thousands or millions of orbiting bodies a relitisitic kill device might be lethal to any one colony but won't do much to your civilisation.


Quote:
So, the basic idea is that any species capable of interstellar travel necessarily is also capable of planetary ecocide (I suppose that's the best word? Destruction of the biome of a planet). So, what risk of genocide of your species is acceptable?
How long after becoming a potential target will any species remain localised on a single planet? How long after that will that original homeworld remain the economic or industrial centre of that civilisation and thus a reasonable target for such an attack?
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Old 14th November 2017, 02:03 AM   #23
The Great Zaganza
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Originally Posted by Roboramma View Post

That makes sense if your species is localised on a planet. But if you have colonised thousands or millions of orbiting bodies a relitisitic kill device might be lethal to any one colony but won't do much to your civilisation.
if you target the local star instead of a planet, you could cause eruptions that can sterilize the entire solar system.
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Old 14th November 2017, 02:05 AM   #24
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The idea that we're not hearing from countless ET civilisations because they're maintaining radio silence to hide from genocidal super aliens seems a bit... fanciful.

For it to be feasible there would have to have been interstellar contact between other species, one of which would have to have been destroyed by the Borg/Predators/Empire, which would have caused the others to start hiding.
However, if there was extensive contact between these species in the years leading up to the planetary genocide, I think the Space Nazis would be able to locate the other guys too. And all of the surviving species that had been in contact would have to have come to the same conclusion at the same moment.
And none of this should affect the (supposedly myriad) species that would not have come into contact with the bad guys, so we should still be able to pick up their signals. Unless you'd want to posit some kind of pan-galactic society that only Earth is excluded from.
It all reads more like a science-fiction movie plot than a reasonable hypothesis for why we don't pick up alien transmissions all of the time...

I prefer the Black Forest Theory: The aliens are staying away because they're allergic to cherry chocolate cake.
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Old 14th November 2017, 02:09 AM   #25
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Originally Posted by The Great Zaganza View Post
if you target the local star instead of a planet, you could cause eruptions that can sterilize the entire solar system.
Out to the distance of the Oort cloud? And assuming we are living inside of rather than on top of our colonies?
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Old 14th November 2017, 02:36 AM   #26
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So this is a theory about the behaviour of intelligent species? There is a sample size of one species, and it doesn't conform to the rule?

I have a theory that I will nearly always roll a six on a die. I roll it once and roll a three. I would now like to write a book, make YouTube videos and go on a lecture series to explain my theory.
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Old 14th November 2017, 02:50 AM   #27
The Great Zaganza
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Originally Posted by Roboramma View Post
Out to the distance of the Oort cloud? And assuming we are living inside of rather than on top of our colonies?
ok, maybe not enough to exterminate a species, but enough to cripple a civilization severely.
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Old 14th November 2017, 03:14 AM   #28
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The theory doesn't make much sense to me. If intelligent civilizations keep quiet or get wiped out, then how would any newly-evolving civilizations get to know that? Presumably they would either just have to correctly guess the situation and keep quiet right from the outset, or they'd be wiped out by an existing civilization.

It would also mean that successful surviving civilizations wouldn't have any accurate idea of how many other civilizations there might be out there - they could tell that there is at least one other (by finding wiped-out planets that they knew they hadn't wiped out themselves) but they wouldn't know whether there was only one other civilization or millions. They could try to carry out covert spying missions to find other civilizations - but presumably if they found any they would then quickly wipe them out - or maybe they'd choose not to even try spying lest the spies be discovered so revealing their own civilization's existence.
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Old 14th November 2017, 07:58 AM   #29
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Originally Posted by Roboramma View Post
I don't think that follows. If the challenges to survival are not great in proportion to a species' ability to control it's environment, it can have many other priorities and yet still manage to survive.

In general each individual will have a survival instinct, as the genes for this will have been selected for, but that doesn't necessarily translate into valuing the survival of the species.

Still, I do find it likely that members of any species will tend to put more value on their own species than on other species.
The idea is if it comes down to a choice. Sure, we want to saves the apes, the whales, the dolphins, etc...but if we had resources limited enough and it came down to them or us, we'd be saying goodbye.

Plus, evolution. If a species evolves not to value itself (by whatever mechanism, species or individual), it doesn't survive. That translates to valuing species survival, at least in the aggregate.

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We have another thread here where we've been discussing non-relativistic interstellar travel. The time scales are very long and there are some technological requirements (the ability to rebuild or repair all the components of your ship on your ship) but I personally find it not only plausible but perhaps more plausible than relativistic space travel, at least for any large scale ship.
Yes, that's a possibility. But the costs are high for any large-scale ship, relativistic or not. And we have current theoretical models now for ships that could reach relativistic speeds.

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That makes sense if your species is localised on a planet. But if you have colonised thousands or millions of orbiting bodies a relitisitic kill device might be lethal to any one colony but won't do much to your civilisation.
That depends on where they are. I really don't expect to see civilizations colonizing multiple solar systems as the norm. And if they're all in one system, then a relativistic device (or more likely, several) can easily take out all of them: large devices for the planets, and some designed to break into pieces to catch various orbiters. Plus, how long will an artificial environment last without the planets supporting them? Most are still going to need something from down below.

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How long after becoming a potential target will any species remain localised on a single planet? How long after that will that original homeworld remain the economic or industrial centre of that civilisation and thus a reasonable target for such an attack?
On a single planet? Maybe not. But unless they can get somewhere else, and do it without being detected, even a single solar system is susceptible.

Now, all that is just to say the idea isn't entirely unreasonable. It's very low-probability, I agree. It would take a very specific set of circumstances to start this sort of cycle. Most I've seen have relied on detection via gamma rays. Current theories for interstellar travel at relativistic speeds rely on antimatter engines of some type, and matter-antimatter reactions produce very characteristic gamma ray emissions. Now, as to how far away those can be detected, I don't know.

But like I said, I don't think it's a likely idea myself...just mainly pointing out it's not as silly as the "Martians are coming for our women" idea
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Old 14th November 2017, 08:10 AM   #30
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Just as an addendum, the book "A Killing Star", by Charles R. Pellegrino and George Zebrowski, goes into the idea. While it's fiction, it does includes pieces of an actual discussion among scientists about the idea, and goes into a lot more detail. They do a better job of explaining the reasoning behind it than I can, as well as giving some additional details on R-bombing (the authors are the ones that actually coined the term) and similar.

https://en.wikipedia.org/wiki/The_Killing_Star
https://www.amazon.com/Killing-Star-.../dp/1511399082
https://www.goodreads.com/book/show/...e_Killing_Star

In their scenario, the alien civilization that attacked Earth had actually been taken over by their own AI creations, whose logic decided that no potential threat to the species could be allowed. Two things "targeted" Earth: the detection of characteristic gamma rays from matter-antimatter reactions, and the Michael Jackson worldwide "We Are the World" broadcast, which indicated to the aliens a unified world government
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Old 14th November 2017, 08:23 AM   #31
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Originally Posted by Hellbound View Post
Plus, evolution. If a species evolves not to value itself (by whatever mechanism, species or individual), it doesn't survive. That translates to valuing species survival, at least in the aggregate.
Again, that doesn't follow. There's no evolutionary mechanism that necessarily causes individuals of a species to value the survival of the species. As long as the individuals all go on living and reproducing, the species will tend to survive whether they care about it or not. So, as I said, there is an evolutionary mechanism that will tend to favour a survival instinct, but that's not related to the species as a whole.



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Yes, that's a possibility. But the costs are high for any large-scale ship, relativistic or not. And we have current theoretical models now for ships that could reach relativistic speeds.
So:
"2. The technological ability to travel from one star to another necessarily entails the ability to reach relativistic speeds...some significant fraction of the speed of light."
Is false.



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That depends on where they are. I really don't expect to see civilizations colonizing multiple solar systems as the norm. And if they're all in one system, then a relativistic device (or more likely, several) can easily take out all of them: large devices for the planets, and some designed to break into pieces to catch various orbiters. Plus, how long will an artificial environment last without the planets supporting them? Most are still going to need something from down below.
The colonies can take advantage of exactly the same mechanism to avoid getting hit as you mentioned with the weapon: they can make small random course corrections.

Also, I'm thinking about colonising the Oort Cloud. We are talking about billions of orbiting bodies, and they are not at all easy to see. How exactly are you going to attack those?
If our colonies are closer in, for instance in the inner solar system, maybe made from the asteroid belt, they will present an easier target, but they will still be very spread out. I am having a hard time envisioning a weapon that can attack them all.

And you do need to attack them all, otherwise you invite counter attack.

In fact the logic here might be enough to build a weapon as a deterrent, but not to actually make the attack, which would in turn invite counter attack. We're left with a situation very similar to a nuclear standoff.



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On a single planet? Maybe not. But unless they can get somewhere else, and do it without being detected, even a single solar system is susceptible.
I'm not seeing it.

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Current theories for interstellar travel at relativistic speeds rely on antimatter engines of some type, and matter-antimatter reactions produce very characteristic gamma ray emissions. Now, as to how far away those can be detected, I don't know.
For thermodynamics reasons I don't think we'll ever be producing anti-matter in large quantities.

The only way that we know how to produce it at present is so inefficient as to be basically useless for the sorts of purposes we're talking about, even if we take optimistic scenarios for the sorts of resources we have at our disposal (those of the whole solar system).

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But like I said, I don't think it's a likely idea myself...just mainly pointing out it's not as silly as the "Martians are coming for our women" idea
Oh, I agree that it's not silly on the face of it. I just think that the argument doesn't quite work when you look at it deeply, but there are some assumptions I'm making about what's possible.
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Old 14th November 2017, 09:08 AM   #32
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Originally Posted by Roboramma View Post
Again, that doesn't follow. There's no evolutionary mechanism that necessarily causes individuals of a species to value the survival of the species. As long as the individuals all go on living and reproducing, the species will tend to survive whether they care about it or not. So, as I said, there is an evolutionary mechanism that will tend to favour a survival instinct, but that's not related to the species as a whole.
Eh, I think it's a bit of semantics. Basically, if another species is wiping you out, you aren't going to sit back and take it. Survival instinct is all that's needed.

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So:
"2. The technological ability to travel from one star to another necessarily entails the ability to reach relativistic speeds...some significant fraction of the speed of light."
Is false.
Technically maybe. I don't see slow-colonization ships being feasible for quite some time, if ever. But that's an arguable point. Or more succinctly, I think that by the time we had the capability for that, we'd have the capability for relativistic craft, and I strongly suspect the latter would be cheaper (resource-wise).

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The colonies can take advantage of exactly the same mechanism to avoid getting hit as you mentioned with the weapon: they can make small random course corrections.
Yes, but your relativistic ships can be guided, and the small course corrections they make are in response to where the incoming missile used to be, so you don't know if you're moving away or towards it's path. Plus, against small targets like that, a better option is to have the relativistic device simply explode once it gets close, and shower the entire area with relativistic particles.

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Also, I'm thinking about colonising the Oort Cloud. We are talking about billions of orbiting bodies, and they are not at all easy to see. How exactly are you going to attack those?
Simple detection system that home in on any EM emissions as they approach the target system? Again, unless the colonies all stay quiet (which is the premise of the theory...that they realize they can be attacked and are quiet so as not to be a target), they can bet found and detected.

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If our colonies are closer in, for instance in the inner solar system, maybe made from the asteroid belt, they will present an easier target, but they will still be very spread out. I am having a hard time envisioning a weapon that can attack them all.
Well, there's the problem. Weapons. You wouldn't send just one. You'd send two per planetary body you knew to target, and several waves behind those. You're up-front would transmit data back to the follow-ons on where they detected signals and similar.

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And you do need to attack them all, otherwise you invite counter attack.

In fact the logic here might be enough to build a weapon as a deterrent, but not to actually make the attack, which would in turn invite counter attack. We're left with a situation very similar to a nuclear standoff.
Yeah, personally I see that as the more likely outcome, assuming any of it is possible at all.

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I'm not seeing it.

For thermodynamics reasons I don't think we'll ever be producing anti-matter in large quantities.

The only way that we know how to produce it at present is so inefficient as to be basically useless for the sorts of purposes we're talking about, even if we take optimistic scenarios for the sorts of resources we have at our disposal (those of the whole solar system).
Well, partly I don't think we've ever designed anything specifically for efficiency in antimatter production. Most of what we currently produce is more of a side-effect of research. I don't know enough about it to speak to the truth of that, though.

Also, it doesn't take much antimatter to power a drive (for an AM thermal rocket, anyway): Inject a small amount into your reaction mass in the chamber, and the resulting explosion adds thrust. This can be any ratio from 1:1 matter/antimatter to 1:100 or 1:1000 or whatever. And remember, if you're looking at R-bombing, you don't need fuel to slow down .

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Oh, I agree that it's not silly on the face of it. I just think that the argument doesn't quite work when you look at it deeply, but there are some assumptions I'm making about what's possible.
Yeah, it's very unlikely like I said. I put it along the same lines of probability as "Earth is the only life in the universe". Possible, but I'm not holding my breath.

I do think that, given sufficient antimatter, one could easily sterilize a whole star system...at least to the point of it not being sustainable anymore. However, as you add additional colonies and such, it gets progressively more expensive, to the point that you could easily destroy your own civilization in the process of trying to target another. I don't think, though, there's any technical barrier to it...just not really feasible from a logical/resource perspective. And part of the original idea was that you're targeting civilizations right as they show signs of access to space travel: when they first develop the capability for relativistic flight. Not a lot of time for numerous scattered colonies in that scenario.
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Old 14th November 2017, 07:06 PM   #33
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Regarding anti-matter:

http://www.iop.org/resources/topic/archive/antimatter/
Quote:
However, antimatter currently takes far too long to produce, and at too high an energy cost, for either weapons or fuel to be practicable. CERN claims it has taken several hundred million pounds to produce just a billionth of a gram, and that to make a gram of antimatter would take about a 100 billion years.
100 billion years/gram is a pretty slow rate to be producing fuel for your spacecraft. Maybe if you build a billion CERNs... you can get your production up to 100 year/gram. That's still too slow when you need kilograms to tons of fuel/spacecraft, even for small craft to get up to relativistic speeds, you're still talking about hundreds of thousands to millions of years (and that's if you have billions of CERNs producing your fuel) to fuel a single spacecraft. But you need millions of spacecraft to attack all of our colonies...

Meanwhile, how much does it cost?

https://en.wikipedia.org/wiki/Antimatter#Cost
Quote:
Scientists claim that antimatter is the costliest material to make.[58] In 2006, Gerald Smith estimated $250 million could produce 10 milligrams of positrons[59] (equivalent to $25 billion per gram); in 1999, NASA gave a figure of $62.5 trillion per gram of antihydrogen.[58] This is because production is difficult (only very few antiprotons are produced in reactions in particle accelerators), and because there is higher demand for other uses of particle accelerators. According to CERN, it has cost a few hundred million Swiss francs to produce about 1 billionth of a gram (the amount used so far for particle/antiparticle collisions).[60] In comparison, to produce the first atomic weapon, the cost of the Manhattan Project was estimated at $23 billion with inflation during 2007.

$25 billion/gram is a high price, and positrons aren't a good candidate fuel source as they are going to be very hard to deal with in quantity, what you need is something like anti-hydrogen atoms. So we really need to be looking at the figure of $62.5 trillion/gram.

Of course as you say, maybe that's just because we haven't been trying to produce the stuff in a cost-effective manner.

In another thread Ziggurat made a simple point about the thermodynamics of anti-matter production that I think applies here:

Originally Posted by Ziggurat View Post
An electron or positron's rest mass energy is about 511,000 eV. A typical room-temperature thermal photon has an energy of about 0.026 eV. So one electron or positron has the energy of about 20,000,000 room-temp thermal photons. The entropy difference here is gigantic. You can arrange your ~20,000,000 photons in so many more ways than you can arrange your one electron or positron (yes, I know they come in pairs). The task of converting energy from a high-entropy state to a low-entropy state is inefficient (you've got to expend energy to increase entropy elsewhere), and the larger the disparity in entropy, the more inefficient the process is. Energy concentrated into a particle is very low entropy. It gets much worse if you want to make a proton-antiproton pair, which you would probably need to do since storing large amounts of just positrons isn't likely to work.
That's a more fundamental issue that we can't really overcome through future technologies and innovation.

So, unless we find a source of naturally occurring anti-matter I don't think it's a likely "fuel of the future".
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Old 14th November 2017, 07:11 PM   #34
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Originally Posted by Hellbound View Post
Eh, I think it's a bit of semantics. Basically, if another species is wiping you out, you aren't going to sit back and take it. Survival instinct is all that's needed.
My point is that individuals may care about their own survival but not that of the species as a whole. I think it's an important distinction that may or may not matter depending on the specifics of the situation.



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Technically maybe. I don't see slow-colonization ships being feasible for quite some time, if ever. But that's an arguable point. Or more succinctly, I think that by the time we had the capability for that, we'd have the capability for relativistic craft, and I strongly suspect the latter would be cheaper (resource-wise).
I disagree, based on what I see as the challenges of relativistic spacecraft, one being the extremely high energy costs, but you may be right.


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Yes, but your relativistic ships can be guided, and the small course corrections they make are in response to where the incoming missile used to be, so you don't know if you're moving away or towards it's path. Plus, against small targets like that, a better option is to have the relativistic device simply explode once it gets close, and shower the entire area with relativistic particles.
The guidance of the missile is also in response to where the colony used to be. Their velocities are relative. From the perspective of the missile it's the colony that's moving toward it at relativistic speeds. A small change in the colony's relative motion will leave it in a very different position. If I make random course changes each of which puts me millions of kilometers away before you become aware of the course change, how do you target me?
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Old 15th November 2017, 07:20 AM   #35
Hellbound
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Originally Posted by Roboramma View Post
The guidance of the missile is also in response to where the colony used to be. Their velocities are relative. From the perspective of the missile it's the colony that's moving toward it at relativistic speeds. A small change in the colony's relative motion will leave it in a very different position. If I make random course changes each of which puts me millions of kilometers away before you become aware of the course change, how do you target me?
Well, it wasn't so much that, but the problem is as that effect lessens (the R-bomb gets closer), you have much less time to make your maneuver. In any case, R-bombs are typically planet-killers, not satellite killers. But let's run some math just for fun

Let's assume your colony is capable of 1m/s acceleration (just over .1G, which is a ridiculously high amount for a typically stationary structure, and respectable even for a designed spacecraft, but still). That 1,000,000 km course change will take you 31,623 seconds, or about 527 minutes, or close to 9 hours...and that's assuming you accelerate the entire time.

During that same time, assuming a velocity around .5c, the R-bomb will travel 4,743,416,490km. That's roughly 32 AU (just under). That means to make that course change, you'd have to detect the incoming R-bomb, decide it was targeting your colony, and start your maneuvers before the R-bomb got inside the orbit of Neptune (roughly). ETA: And have enough fuel and energy to maintain those maneuvers for 9 hours.

For satellites and such, though, I doubt they'd be directly targeted with R-bombs...and most would be hard-pressed for survival without planetary support, unless you're talking about a very advanced civilization. And the whole point about the Dark Forest idea is that civilizations are stopped long before they get to this point. Frankly, if it were me, I'd simply have several R-bombs set to break into a cloud of particles at a pre-set distance, and shower the entire solar system (or at least the inner system) with a relativistic dust storm. That wouldn't sterilize planets, but should be more than enough to take care of any orbital infrastructure. And given the relative velocities (if I've done my math right), I can blow my incoming R-bombs up at something like 18000 AU out and have the resulting debris cover an are 1 AU in diameter (That's assuming the .5c incoming velocity, and an explosion of the R-bomb equivalent to the speed of C4...8000m/s).

In any case, though, it's neither here nor there. The ideas of defending against it have the same issues as the attack itself: it's going to need an outrageous amount of resources and a very high technology level

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Old 15th November 2017, 09:23 AM   #36
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Originally Posted by Hellbound View Post

Let's assume your colony is capable of 1m/s acceleration (just over .1G, which is a ridiculously high amount for a typically stationary structure, and respectable even for a designed spacecraft, but still). That 1,000,000 km course change will take you 31,623 seconds, or about 527 minutes, or close to 9 hours...and that's assuming you accelerate the entire time.

During that same time, assuming a velocity around .5c, the R-bomb will travel 4,743,416,490km. That's roughly 32 AU (just under). That means to make that course change, you'd have to detect the incoming R-bomb, decide it was targeting your colony, and start your maneuvers before the R-bomb got inside the orbit of Neptune (roughly). ETA: And have enough fuel and energy to maintain those maneuvers for 9 hours.
I'm talking about making smaller course corrections randomly at random time intervals. If you're worried that a missile that you can't see is coming you just make small changes in to your trajectory all the time. So each course change can be smaller. If I'm in the Oort cloud and I make a small change in course when your missile first launches I might be billions of kilometers away from where you thought I was supposed to be by the time you see me making that change. So now you alter your trajectory, but in the meantime I've made more random changes. Etc.

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For satellites and such, though, I doubt they'd be directly targeted with R-bombs...and most would be hard-pressed for survival without planetary support, unless you're talking about a very advanced civilization.
I don't think you need to be much more advanced than we are now. A few hundred or a thousand years is nothing on these time scales.

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And the whole point about the Dark Forest idea is that civilizations are stopped long before they get to this point. Frankly, if it were me, I'd simply have several R-bombs set to break into a cloud of particles at a pre-set distance, and shower the entire solar system (or at least the inner system) with a relativistic dust storm.
That's a pretty big dust storm. Either each individual target will only get a tiny amount of dust or you will need an incredibly massive dust cloud, and the requisite energy is on a scale that even I'm not comfortable thinking is viable.

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In any case, though, it's neither here nor there. The ideas of defending against it have the same issues as the attack itself: it's going to need an outrageous amount of resources and a very high technology level
I think the defence requires fewer resources than the attack, which is my point.
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Old 16th November 2017, 11:46 AM   #37
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The gases in our atmosphere have been broadcasting the signature of life for half a billion years. If any BEMs that could make it here and have a reason to want our stuff and were so inclined, they would have done so.
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Old 16th November 2017, 09:29 PM   #38
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Originally Posted by Fudbucker View Post
Briefly, dark forest theory is a theory that the universe is a dark forest where it's kill or be killed. The optimum strategy is to hide and hunt, silently taking out anything that might be a threat to you, gobbling up anything that might increase your chances of survival. There's no avoiding infinite chains of suspicion, so the wisest choice, if you meet someone, is to assume hostility on their part. Infant civs like us, who leak like a sieve in the EM spectrum are quickly gobbled up, which is one reason that explains the fermi paradox: most civs hide, suspicious of every other possible civ. The ones that don't hide already got poached.

The problem with this line of thought is that we're not like that. We haven't cloaked ourselves. We broadcast welcome signals. And even if we're a rarity, if there's a lot of civs in the galaxy, there are a bound to be a few more like us. Given enough civs, two friendly ones will eventually find themselves near each other and make contact and cooperate. Wouldn't cooperation lead to faster tech progress than mutual distrust? And if, by some fluky chance, there are a cluster of friendly naive cooperative civs all right next to each other, might they become extremely powerful? Powerful enough to swat down the lone hunter-killers and establish some rules to live by in the forest?

Thoughts?

Primary thought is that it's not a theory in any usual sense of the word - it's a set of conjectures based on potentially faulty assumptions.

We couldn't know whether any of those assumptions are justified because we lack the data points to corroborate or falsify them.

While I think the universe is inevitably predatory because of its thermodynamic fabric, I don't think it then stands to reason that everything within it will only ever be predatory. Life is not about eating whatever you can find, but about surviving at least to reproduce, and while eating is important to provide energy to do that surviving and reproducing, cooperation often provides a much better investment ratio than ubiquitous hostility. You share the rewards, but there is plenty more where that came from, but more importantly, you share the costs - and that efficiency can be scaled.

Any species which makes its way into interstellar space must already be capable of cooperating.
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Old 16th November 2017, 10:07 PM   #39
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Originally Posted by kedo1981 View Post
The gases in our atmosphere have been broadcasting the signature of life for half a billion years. If any BEMs that could make it here and have a reason to want our stuff and were so inclined, they would have done so.
Representatives of an advanced civilisation were on their way here, having followed signs of life for half a billion years; then in 1951 they started picking up broadcasts of "I Love Lucy" so they turned round and went away again.
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Old 17th November 2017, 09:10 AM   #40
Fudbucker
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Originally Posted by kedo1981 View Post
The gases in our atmosphere have been broadcasting the signature of life for half a billion years. If any BEMs that could make it here and have a reason to want our stuff and were so inclined, they would have done so.
Maybe they've been here for a long time, observing.
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