The Great Filter

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The Great Filter

Postby hyksos on February 2nd, 2018, 6:49 pm 

Look up at night at the stars. We do not see the galaxy teaming with interstellar civilizations. Why not?

Different answers to this question have deep-reaching consequences. A few : (1) We are the first advanced civilization. More will come. (2) The galaxy is littered with the ruins of past mighty civilizations which collapsed. (3) We are the only advanced civilization because of an implausible fluke accident that happened to early life on Earth. (4) et cetera (5) et cetera

(2) and (3) are called Great Filters.

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Re: The Great Filter

Postby Serpent on February 2nd, 2018, 7:22 pm 

Bah! There may be any number of planets with intelligent life-forms on them, but -
1. they are at different levels of technological advancement; only 10% have space-flight capability and only 10% of those have been able to send any vehicle beyond their own solar system -
the distances are so vast that those vehicles won't ever encounter one another,
even if some of their trajectories intersect
(There is no reason "we should see something".)

2. Some civilizations may be capable of space flight, but not rich enough to squander resources, too busy with local challenges and other preoccupations, or simply not interested.
(There is no reason to suppose - Star Trek notwithstanding - that all advanced life-forms are humanoid.)

3. Some are organic, maybe symbiotic, rather than mechanical and cannot leave their planets - the source of their life-energy.
(There is no reason to suppose that other planets have the same competitive and over-reproductive drive that propel any species to dominance or to change a hospitable environment to an inhospitable one.)
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Re: The Great Filter

Postby Dave_C on February 2nd, 2018, 10:39 pm 

hmmm... well, the video is an advertisement of course. Might be questionable to post adverts but it is an interesting question.

I think they make a good case for 'filters' but perhaps the first question to ask is whether or not a single filter should be assumed or should we ask how many filters there are along the way to super-intelligent civilizations? Seems to me there could be many. Note this whole idea of filters isn't unlike the Drake equation where we put probabilities to various occurrences, each level representing some degree of 'filtration' if you will.
... The number of such civilizations N, is assumed to be equal to the mathematical product of

I. R∗, the average rate of star formations, in our galaxy,
ii. fp, the fraction of formed stars that have planets,
iii ne for stars that have planets, the average number of planets that can potentially support life,
iv fl, the fraction of those planets that actually develop life,
v fi, the fraction of planets bearing life on which intelligent, civilized life, has developed,
vi fc, the fraction of these civilizations that have developed communications, i.e., technologies that release detectable signs into space, and
vii L, the length of time over which such civilizations release detectable signals,

for a combined expression of:
N = R ∗ f p ⋅ ne ⋅ fl ⋅ fi ⋅ fc ⋅ L [

My understanding - life started early on in the Earth's development, so starting life seems not to be a filter. That could be false of course, but it seems reasonable that the start of life isn't a filter. I'll turn around and propose that this possibly is a filter momentarily (just for fun). :)

The second one, multicellular organisms, does seem like it could be a filter. My understanding is it took billions of years for that step to occur. Perhaps it takes so long that life on a given planet tends to be eliminated before it can take place.

The possibility that intelligent life destroys itself is obviously another 'filter' which might eliminate some large percentage of civilizations.


So I think there's not one filter, we should consider that there are multiple filters which largely correspond to those factors in the Drake equation.

Now, time for some crazy imagination... Let's face the fact that we've not yet determined what phenomenal consciousness is or how it can come about. If it were something science could put it's finger on and study easily, we'd all largely agree on what it is and how it comes about. I have my doubts, I'd consider myself a secular substance dualist. If the development of phenomenal consciousness is a 'filter' then perhaps, like Schrodinger's cat, and for whatever reason I'm not even imaginative enough to imagine, there can only be one phenomenally conscious 'spark' and that spark has already happened, so it can never happen again. If that were the case, if phenomenal consciousness wasn't simply a physical process (albeit, it supervenes on physical processes) but is entailed by an additional substance which can only have one link to our physical world, then the one, most important filter there is in nature, has already been passed through, and perhaps we're on our way to infinite existence whether we want it or not.

If you like sci-fi - in his book "Contact", Carl Sagan talks about this other alien influence that was part of the universe, but was discovered to have left. Maybe there's more than one substance. Maybe we need to get out?
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Re: The Great Filter

Postby hyksos on February 3rd, 2018, 6:47 pm 

vii L, the length of time over which such civilizations release detectable signals,

I was expecting more elaboration on this one, since the cartoon develops this in great detail.

There are other videos about the Fermi Paradox on youtube. This video I linked is only about a particular subheading on the paradox, namely, Great Filters. If Great Filters are not your cup-of-tea, or you are bored talking about them, you can investigate all sorts of weird alternatives.

One is this idea that the advanced civs are not using radio. They are using some kind of beacon tech that humans don't understand yet.

Could talk about the speed of light being a real , hard limit, and therefore it is infeasible for civs to know about each other due to the slowness of their evidential signals moving across the galaxy.
the distances are so vast that those vehicles won't ever encounter one another,
even if some of their trajectories intersect

{ more exotic }. Civilizations progress to holodecks, and then their citizens give up on regular reality.

The cartoon also depicts the filter of (what is clearly) run-away global warming. I'm not sure I buy this tract as being scientific. Global warming would become catastrophic enough for humans to start migrating very far north. At that point in time, it would be obvious from massive societal collapse that we can no longer burn fossil fuels in cars. The remaining few million humans would survive this catastrophe and survive it with most techno knowledge intact. The cartoon shows pollution as killing all life on the surface. I'm not entirely sold on the idea.
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