I don't know why this is tolerated as the top comment when it should have been auto-nuked a long time ago, but:>bozo>moron>cretin>idiocy>ignorant imbecileIt is not a rule of rationality that if you cannot control yourself enough to have basic decency, then your opinions are not valid, but grow up.

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disqus_5bOa2kamAP 5+

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As far as I can tell, you're an ignorant git. What part of "Paleontologist Peter D. Ward, fresh from helping prove that an asteroid had killed the dinosaurs, turned to the Permian problem" are you too stupid to understand?

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"No disaster is totally unforeseeable"

I don't think this is true. For instance, given what was (not) known at the time about radiation, Marie Curie's experiments with radium, polonium and X-rays probably seemed a priori perfectly safe. Her and her husband's cancer were of course very local disasters, but the scenario I have in mind would be global.

Something like this: suppose that it turns out that colliding such and such particles at sufficiently high energies generates a world-killing chain reaction. However, the math needed to predict this in practice requires a lot more technical sophistication than the engineering know-how needed to build such a collider.

Note that experiments often race ahead (sometimes by decades) of the theory needed to explain them. This is true of turbulence, I'm sure it's been true of some particle physics, and it's happening right now in parts of deep learning. (Note also that I'm NOT pointing at particle physics as a likely culprit; it's just the example that most naturally came to my mind.)

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As far as I can tell the author is either a kook or in such a minority position that most people mkaing lists of the possible reasons for the Cretaceous–Paleogene extinction don't both to list his hypothesis. Certainly the evidence for the Asteroid hypothesis seems to have gotten better in the 10 years since that book was written.

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"My understanding is that the previous times large die-offs have increased the CO2/O2 ratio it was because the Earth had turned into a snowball and the rise in CO2 fixed the problem."

No. https://smile.amazon.com/Un...

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Yes, the title of this blog is so ironic.

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"We only have experience of governments on short time scales. Doesn't mean they couldn't exist on longer time scales in the future."

This is the sort of stupid dishonest evasive strawman attack that Hanson is so prone to.

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"In principle, any piece of simple dead matter in the universe could give rise to simple life, then to advanced life, then to an expanding visible civilization."

There's no such principle, bozo. For life to arise there must first be, at the least, replicating molecules that aren't immediately consumed by their environment. The conditions to allow that are likely unusual.

"In practice, however, this has not yet happened anywhere in the visible universe."

You're a moron. It happened on Earth, and it may well have happened numerous other places as well.

"our observation of a dead universe"

We haven't observed a dead universe, you cretin ... we've barely observed the universe at all, and we've only recently even been able to infer the existence of possible life-bearing planets.

I can usually make it through Hanson's streams of idiocy, but this one is too dense, and this subject has been covered many times and by people who are vastly better informed and more intelligent.

(And as always, this ignorant imbecile makes no mention of global warming as part of his filter. And does he even know that the dinosaurs were around for 150M years before the "external disaster" that made the arisal of large mammals possible? If he knew anything about evolution, he would know that "with 1.5 billion years to putter, life seems likely to revive ... big brains, and something as advanced as humans" is baseless nonsense -- big brains aren't generally favored and they aren't "advanced" -- every organism is equally advanced relative to evolution; they all have a common ancestor and the same longevity.)

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Upon reflection, I think my reasoning still holds (albeit to a lesser extent) no matter how much of the great filter you think the future filter accounts for.

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I'd lump this in under "too little coordination". No disaster is totally unforeseeable - if nothing else, if there are no other plausible candidates for the great filter, we can increase our credence that we'll be wiped out by a difficult-to-foresee physical cataclysm. If there were only one benevolent far-sighted ruler, and they assigned significant probability to such a cataclysm, then it'd plausibly be rational to slow experimental science down by a factor of 1000 or more, and in the meantime, to colonise as widely as possible so that some remnants of humanity will escape. (I doubt that such a catastrophe would wipe out all humans no matter how far we spread - if it really would be a galactic-level extinction event, then it doesn't explain the fermi problem, since we'd need a reason why another species hasn't already triggered it and wiped both of us out).

Of course these measures will never be taken, but it's only so far-fetched because we haven't solved coordination problems to a sufficient degree.

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You've basically discussed two types of civilization-killing filters:

1 - "Big external disasters", basically spontaneous natural events. You've dismissed those as unlikely filters, and I agree

2 - "Too much coordination" and "Too little coordination" are basically governance, "social" barriers

I've often wondered about a third type, namely the

3 - "Unforeseeable tech-driven physical cataclism": this was inspired by past speculation that the LHC could produce micro-black holes that rapidly grow and swallow the whole planet. That turned out not to happen (at least according to this site: <http: hasthelargehadroncolliderde...=""/>), and the people who worried about this scenario might very well have all be hacks (i'm not qualified to judge).

Now let's consider hypothetically the following setup:

i) There is some cataclysmic physics-based phenomenom F that destroys all life on any given planet once it occurs in that planet

ii) It turns out that civilizations with sufficiently advanced technological always acquire the skill to perform some experiment E that unleashes F

iii) Furthermore, scientific inquisitiveness pretty much unavoidably leads some group pf researchers to carry out E, without of course realizing the consequences beforehand (or after the fact, for obvious reasons)

iv) It turns out that the theory and empirical evidence required to *predict* that E implies F is in practice not attainable *before* E is actually carried out -- and so no-one ever gets to prove that E implies F (except empirically...)

All of this of course sounds pretty fantastic and sci-fyish, but frankly so does a 13.8 billion-year old universe with no sign of galactic colonization...

Any thoughts on this possibility, or similar scenarios?

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In 2), my "yet", though correct, was misleading. I'm referring to the possibility that expansion(s) stay invisible *indefinitely* to someone who's looked only as hard as we have so far. This may be e.g. because the real action happens wrt the 95% (or more? other shoes may yet drop) of the universe we can't see, relative to which what we *can* see is not worth the expanding civ's time. We've been taught repeatedly that humility in the face of nature is wise. How humble is it to assume that our feeble attempts to date could definitely detect arbitrarily advanced expanding civilization?

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Just via the outside view probably on the order of a billion years, like the first time we went from Eukaryotes to multicellular life?

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I agree. This exact pattern of reasoning has led me to think that we are probably the first in our neighborhood to have cleared the filters that enable a technological society - a conclusion on which I initially placed a very low probability.

But I do see what you're saying. You're wondering whether, on the assumption that the great filter lies ahead, whether it's more likely to be a filter of strangulation or a filter of annihilation. Both seem super improbable, so yeah, it's a hard question. I say annihilation is likelier, because it runs on longer cycles. Post-catastrophic recovery might be too slow to achieve catastrophe-resilience before the cycle restarts, and the clock runs out after not too many cycles. Systems of strangulation require constant maintenance to prevent leaks. Escape attempts are bound to be more frequent.

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If I understand you correctly one possible future filter could be a world order that actively prevents expansion. But I don't think it does need to be active for that. Expansion beyond the solar system presumably is a challenging task that requires a lot of coordination. The social system just needs to be sufficiently concerned with *other* issues that not enough free coordination capacity remains.

My own opinion on this is that significantly more coordination (and energy) is necessary to reliably leave earth or the solar system than is usually assumed. Getting settlers to Australia and establish a colony there required how many ship loads? I wonder how big (in terms of people, area, circulating resources) a society has to be to sustain a certain 'level of civilization' on their own. Do we have historical evidence of that? A village of 1000 on fertile soil can presumably sustain iron age level (if they have access to iron). Australia colonists could sustain equal level civilization there. But could we really package our modern civilization with the ability to create smartphones and GPS in a vessel and send it to Mars or Alpha Centauri?


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