Difference between revisions of "Great Filter"

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The '''Great Filter''' is a proposed explanation for the [http://en.wikipedia.org/wiki/Fermi_paradox Fermi Paradox]. Robin Hanson coined the term in his 1998 essay [http://hanson.gmu.edu/greatfilter.html The Great Filter]. The titular Filter refers to whatever forces prevent the development of an interstellar civilization. These forces might be present at any stage of development, i.e. an "early filter" which prevents the formation of life, a "middle filter" which prevents life from attaining sentience, or a "late filter" which prevents sentient life from spreading beyond its home planet. Any of these filters could account for the lack of visible evidence for extraterrestrial life. Hanson argues that our lack of knowledge regarding the position of the filter should make us more cautious, as a "late filter" would imply that we have low odds of successfully colonizing space and our survival may be in danger.
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The '''Great Filter''' is a very improbable step leading to an interstellar civilization, it is a proposed explanation for the[http://en.wikipedia.org/wiki/Fermi_paradox Fermi Paradox]. Robin Hanson coined the term in his 1998 essay [http://hanson.gmu.edu/greatfilter.html The Great Filter].
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If we know that many other habitable planets fulfilling the conditions for life to flourish until a interstellar civilization are bound to exist and at the same time know about the [http://lesswrong.com/lw/ih/absence_of_evidence_is_evidence_of_absence/ lack of evidence] for the existence of other civilizations this implies the existence of a extremely improbable step, a Great Filter, in the path leading from the basics conditions for originating life to the emergence of interstellar civilizations.  
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The Great Filter might be the transition from prokaryotes to eukaryotes, or from unicellular to multicellular life forms, or yet the appearance of photosynthesis. Should this be the case, we have already passed through the improbable region, the filter is behind us and we shouldn’t worry. But the hard step might also be ahead of us: to survive the creation of nuclear bombs, [[AGI]] biotechnology, [[nanotechnology]] or an asteroid impact [http://www.global-catastrophic-risks.com/docs/Chap01.pdf]. In this scenario, we are passing or will pass through the improbable region and we should worry.  Estimating the location of the Great Filter is a crucial task for dealing with [[Existential risk]]. [http://hanson.gmu.edu/greatfilter.html Many] [http://hanson.gmu.edu/hardstep.pdf efforts] [http://www.stat.berkeley.edu/~aldous/Papers/GF.pdf have] [http://www.nickbostrom.com/papers/fermi.pdf been] [http://www.global-catastrophic-risks.com/docs/Chap01.pdf made] [http://meteuphoric.wordpress.com/2010/03/23/sia-doomsday-the-filter-is-ahead/ in] that direction, but much remains uncertain.
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Traces of life in other planets are an evidence for a later Great Filter[http://www.youtube.com/watch?v=_W8zu7lFmhY]. Any indication, anywhere in the universe, that life evolved until a period anterior to ours it’s an indication that evolving until such anterior period isn’t so improbable.  Hence, the Great Filter probable location shifts in the future direction, enhancing the chances he is just ahead of us.
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The study of [http://en.wikipedia.org/wiki/Extinction_event#Major_extinction_events past mass extinctions] and astrobiology can provide ideas for the estimation of the Great Filter probabilistic distribution. However, there are many difficulties involved. For instance, one can not estimate the improbability of a step based on its completion time. Robin Hanson gives the following example in his [http://hanson.gmu.edu/greatfilter.html  seminal paper]:
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“…say you have one hour to pick five locks by trial and error, locks with 1,2,3,4, and 5 dials of ten numbers, so that the expected time to pick each lock is .01,.1, 1, 10, and 100 hours respectively. Then just looking at those rare cases when you do pick all five locks in the hour, the average time to pick the first two locks would be .0096 and .075 hours respectively, close to the usual expected times of .01 and .1 hours. The average time to pick the third lock, however, would be .20 hours, and the average time for the other two locks, and the average time left over at the end, would be .24 hours. That is, conditional on success, all the hard steps, no matter how hard, take about the same time, while easy steps take about their usual time”
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[http://hanson.gmu.edu/hardstep.pdf  On a subsequent paper], Hanson constructs a simulation of the hard steps distribution given earth habitable time, and concludes that there is a total of 4 to 7 hard steps uniformly distributed . It also shows that since hominid evolved there has been at least one hard step and that the best extinction model that fits all these requirements is [http://www.pnas.org/content/91/15/6735.full.pdf William Schopf’ model]. Taking evolutionary arguments for AGI and [http://wiki.lesswrong.com/wiki/Observation_selection_effect observational selection effects] together, [http://www.nickbostrom.com/aievolution.pdf Bostrom and Shulman argue] that Hanson’s results can narrow the bounds on where AGI engineering difficulty can be found.
  
Katja Grace [http://meteuphoric.wordpress.com/2010/03/23/sia-doomsday-the-filter-is-ahead/ argues] on her blog that the [[self indication assumption]] should lead us to suspect that the Great Filter is still ahead of us.
 
  
 
==Blog posts==
 
==Blog posts==
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==External links==
 
==External links==
  
*Hanson, Robin (1998) [http://hanson.gmu.edu/greatfilter.html The Great Filter - Are We Almost Past It?]
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*Robin Hanson’s Great Filter original paper: [http://hanson.gmu.edu/greatfilter.html The Great Filter - Are We Almost Past It?]
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*A simulation of the hard steps distribution: [http://hanson.gmu.edu/hardstep.pdf Must Early Life Be Easy? The Rhythm of Major Evolutionary Transitions] by Robin Hanson
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*Strong candidates for present Great Filters: [http://www.global-catastrophic-risks.com/docs/Chap01.pdf Introduction of the book “Global Catastrophic Risks”, summarizing it] by Nick Bostrom
 
*[http://meteuphoric.wordpress.com/2010/03/23/sia-doomsday-the-filter-is-ahead/ SIA Doomsday: The filter is ahead] by Katja Grace
 
*[http://meteuphoric.wordpress.com/2010/03/23/sia-doomsday-the-filter-is-ahead/ SIA Doomsday: The filter is ahead] by Katja Grace
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*An audio with Bostrom talking about how finding traces of life on mars is terrible bad news: [http://www.youtube.com/watch?v=_W8zu7lFmhY Nick Bostrom on life on Mars]
  
 
==See also==
 
==See also==

Revision as of 07:57, 1 September 2012

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The Great Filter is a very improbable step leading to an interstellar civilization, it is a proposed explanation for theFermi Paradox. Robin Hanson coined the term in his 1998 essay The Great Filter.

If we know that many other habitable planets fulfilling the conditions for life to flourish until a interstellar civilization are bound to exist and at the same time know about the lack of evidence for the existence of other civilizations this implies the existence of a extremely improbable step, a Great Filter, in the path leading from the basics conditions for originating life to the emergence of interstellar civilizations.

The Great Filter might be the transition from prokaryotes to eukaryotes, or from unicellular to multicellular life forms, or yet the appearance of photosynthesis. Should this be the case, we have already passed through the improbable region, the filter is behind us and we shouldn’t worry. But the hard step might also be ahead of us: to survive the creation of nuclear bombs, AGI biotechnology, nanotechnology or an asteroid impact [1]. In this scenario, we are passing or will pass through the improbable region and we should worry. Estimating the location of the Great Filter is a crucial task for dealing with Existential risk. Many efforts have been made in that direction, but much remains uncertain.

Traces of life in other planets are an evidence for a later Great Filter[2]. Any indication, anywhere in the universe, that life evolved until a period anterior to ours it’s an indication that evolving until such anterior period isn’t so improbable. Hence, the Great Filter probable location shifts in the future direction, enhancing the chances he is just ahead of us.

The study of past mass extinctions and astrobiology can provide ideas for the estimation of the Great Filter probabilistic distribution. However, there are many difficulties involved. For instance, one can not estimate the improbability of a step based on its completion time. Robin Hanson gives the following example in his seminal paper: “…say you have one hour to pick five locks by trial and error, locks with 1,2,3,4, and 5 dials of ten numbers, so that the expected time to pick each lock is .01,.1, 1, 10, and 100 hours respectively. Then just looking at those rare cases when you do pick all five locks in the hour, the average time to pick the first two locks would be .0096 and .075 hours respectively, close to the usual expected times of .01 and .1 hours. The average time to pick the third lock, however, would be .20 hours, and the average time for the other two locks, and the average time left over at the end, would be .24 hours. That is, conditional on success, all the hard steps, no matter how hard, take about the same time, while easy steps take about their usual time”

On a subsequent paper, Hanson constructs a simulation of the hard steps distribution given earth habitable time, and concludes that there is a total of 4 to 7 hard steps uniformly distributed . It also shows that since hominid evolved there has been at least one hard step and that the best extinction model that fits all these requirements is William Schopf’ model. Taking evolutionary arguments for AGI and observational selection effects together, Bostrom and Shulman argue that Hanson’s results can narrow the bounds on where AGI engineering difficulty can be found.


Blog posts

External links

See also