Does a "Great Filter" Exist? - (Or Why We've Never Seen Any Sign of Alien Life)

The Great Filter is the idea that there is some single, almost insurmountably improbable barrier on the path to the stars that explains why we've never seen any sign of alien life.  It combines aspects of astrology, biology and history to arrive at one inescapable conclusion: university professors dream of book deals.

Robin Hanson of George Mason University posits a "Great Filter" that prevents the rise of intelligent, self-aware, technologically advanced, space-colonizing civilizations. The "filter" would be one or more improbable steps along the path that starts with the creation of a planet and ends with a race capable of colonizing the galaxy.

Somewhere between those two points, philosopher Nick Bostrom points out, "the Great Filter operates, and it must be powerful enough that even with all the billions of possible starting worlds on which life might evolve - all those rolls of the cosmic dice - one ends up with nothing: no aliens, no spacecraft, no signals, at least not in our neck of the woods."

The very existence of life makes finding a four-leafed clover with winning lottery tickets for leaves look like a sure thing.  Add the staggering improbability of our evolution from single cells and you end up with odds so vast they've driven the invention of everything from the Drake equation to an invisible sky-beard who seems unnecessarily preoccupied with what we do one day out of every seven.  People who study this subject file all that under "Shit we already knew", and were too busy actually working on the science to come up with a garbage buzzword phrase that would look really awesome in bold type on the cover of a hardback book (available now for $29.99!)  Luckily Robin Hanson was ready to do that for them.

There isn't actually a book yet, but the Great Filter "theory" is so clearly designed to be publisher-ready you can almost see the page numbering.  It talks in grand terms about a vast threat facing humanity, and if it never seems to have any idea what that threat actually is, was or will be then who cares?  Most of the 'evidence' is based on the scarcity of life in the cosmos in general and how that describes threats to Earth specifically, otherwise known as "Fundamental misunderstanding of statistics #1".  He goes on to talk around this ethereal menace and all the effects it could have on THE SURVIVAL OF EARTH, combining lots of different fields in compelling pop-science friendly chapters without ever coming up with an actual result.

Not that we're claiming that Professor Hanson doesn't understand all this; just that he's made a tactical decision not to care.  His real intentions are further revealed by the way he throws around "possibility of world-destroying physics experiments" (we're assuming he'll scribble "I'M TALKING ABOUT THE LARGE HADRON COLLIDER" on autographed copies).  This is a great buzzword for catching media attention and popular sales, at the tiny price of sacrificing even the pretense of scientific validity.  Everyone who's even heard of the basic physics of the LHC knows these cataclysm quotes are garbage.

Bostrom, director of the awesomely titled Future of Humanity Institute at Oxford University, claims that the Great Filter poses an "Existential Risk".  That's a perfect choice of words because he thinks it means a threat to our very existence, when it's really a made-up Nietzschean problem for people who should be delighted but are determined to be miserable anyway.  He confirms this assessment by telling us we should take any discovery of alien life as terrible news, as that would put this mysteriously unspecified Filtering Boogeyman in our future instead of the past.

Listen: if the Phoenix Lander discovers life on and you can honestly call that a bad thing, then it's not just that you aren't a scientist.  We're not even sure you could be described as human.

Posted by Luke McKinney.

Related Galaxy posts:

The METI Controversy: Is Detection by Alien Life a Threat to the Human Species?
Babelfish -Universal Translator Will Allow ET to Speak English
The 1.5 Gigayear Technology Gap
Advanced Civilizations in the Universe -A Galaxy Insight
 "The Great Silence" -A Galaxy Insight
 NASA's "New Worlds Observer" Will be Able to Spot Oceans, Continents and Clouds on Small Rocky Planets
MIT Asks: How Would Extraterrestrial Astronomers Study Earth?
Harvard-Smithsonian Scientists Zero In On Key Sign of Habitable Worlds
Cruising the Goldilocks Zone -The Search for Super Earths
Dead Zones in the Search for Extraterrestrial Life

Source LinkS

Nick Bostrom on the Great Filter

Please Give Me A Book Deal (aka The Great Filter Page)

Comments

[ray braxas]

The scientists are dancing around with words for fear of the real implications of where these ideas are going. Somebody is going to come clean very soon.

[EvilCosmicMonkey from Knoxville]

The " Great Filter " would seem to be the speed of light, as far as contacting any other extra - terrestrial civilizations. For the forseeable future, any contact is going to be one way. Even though our closest interstellar neighbor is merely 4 l.y. away, if there's intelligent life on one of the planets there ( there are planets there, right ? ), we won't be able to come a - visiting until we develop a way to travel at or near light speed, even though we should've intercepted signs of civilization if they developed communication technology.

The barrer of time is the same reason we can't contact the people of ancient Egypt, Mesopotamia, Imperial China, etc.

[Brian H]

Luke, you got a bit careless as you came to the finish line; "if the Phoenix Lander discovers life on and you can...". I b'lieve the word "Mars" comes after "on". ;)

Ever heard of the { answers.com/topic/charles-r-pellegrino } Pellegino Postulate? It says that some, or most, dominant planetary species will be predator stock, inclined to eliminate competition. Some might want to do so pre-emptively, and therefore use { answers.com/topic/relativistic-kill-vehicle } RKVs (Relativistic Kill Vehicles) to wipe out planets that have developed or might develop technological civilization.

Since even ONE such species would be enough to erase all reachable competition, the only rational course for EVERY technological species is to protect itself by adopting the same strategy pro-actively. Therefore we, also, should set up our near-solar automated factories turning them out and preparing to cut loose at any and every planet we spot with any chance of developing advanced life. Not to do so is suicidal.

Not that it's likely to do much good, because the RKVs targeting Earth are probably already on the way. Our only real chance of survival is to quickly get into deep space and colonize some inconspicuous planet(s), and stay very, very, quiet.

How's that for a "Great (Self-)Filter"?

[EvilCosmicMonkey from Knoxville]

Brian H.-

A lot is still contingent on that sometimes pesky 2 - letter word " if ". BTW, would RKV's be in the form of some kind of Von Neuman ( self - replicating ) machine ?

Time & distance ( & of course, technological development ) are still bigger barriers than anything. Also the " light - speed limit ".

[Brian H]

No, the RKVs are simple beasts, just a ~2ton(?) net weight vehicle with advanced target guidance accelerated by initial rail-gun solar-orbital setups, and using an on-board anti-matter engine to get up to about .92C. They would become visible about 1/12 of the actual time of impact (when it looks like they're 1 (light) year away, they're actually about 1 light month away). They can't be deflected or destroyed, and could pretty much sterilize a planet's surface on impact, or at least return it to the microbial life only stage.

They are "fire and forget" tech; the hope is that they nip any potential competition before it has advanced to the point of detecting and targeting you. Given the time lags involved, it's quite possible for two planets to wipe each other out.

Read "Flying to Valhalla" by Pellegrino. Asimov helped him with the "Rules of Alien Contact" underlying the plot.

[jer35mx]

Well, those three last answers were a kind of thinking, I won't ask if you support or aprove the russian trials for communications with other stars. But, it's interesting if you put 10 kgs. of "literature" of the world in the ¿2 1/2? tons. device we can share all our culture. Different kinds of thinking.

[Coyote]

Luke McKinney: do you actually work for Daily Galaxy; are you paid, or are you and others here merely commentators, or free bloggers? Many of the articles here are written as if by amateurs and promoters, as in Rah rah rah! Go science! To the detriment of thoughful balanced articles.

For example, what the hell were you trying to say here, except to condemn the idea that advanced alien life was probably unlikely? I could not make any sense out your article, except your deep-seated belief that the Star-Trek version of space was actually real.

Look there are many reasons why we apear to be alone, yet you explored none.

Mathematically, the problem is that the distances of space are so large and the time so long and that civilization's typical lifespan so short (as evidenced by our own experience and the precariousness of our current situation), that it is extremely rare to have two civilizations near enough each other in time/space lasting long enough to develop the technology to enable contact.

Interstellar space travel is impossible; distances are too great and the speed of light is not fast enough. “Warp drives” like Star trek to speed things up will still be too slow. The other limiter is the tendencies of civilizations to be short and to self-destruct from self-created “Progress Traps” (Ronald Wright).

If we survive long enough to create some sort of quantum drive or “stargate,” time/space travel may be possible, but more likely interdimensional of some sort.

[ANNUNAKAI]

WE ARE ALREADY HERE YOU FOOLS , AND WE HAVE BEEN HERE IN YOUR SOLAR SYSTEM FOR EONS .
ARE YOU BLIND , DEAF OR JUST ON THE UNIVERSAL WEED OF LIFE.
SOME OF YOU WHO WATCH THE X FILES AND UFO CHANNELS ARE AWARE OF US BUT WE ARE TRICKY AND IT DOES NOT TAKE A MENTAL GIANT TO CAMOFLAGE OUR PRESENCE.

I HAVE THE AUDACITY TO TELL THIS TO YOU NOW AND YOU WILL SCOFF AT IT.... WHAT FOOLS YOU EARTHLINGS ARE !

YOU WILL NEVER FIND US .

ENKI AND ENLIL

OF THE ANNUNAKAI

[EvilCosmicMonkey from Knoxville]

RKV's sound like an ultimate WoMD !! But an anti - matter propulsion system still sounds like it belongs in the realm of science fiction.
As to interstellar contact -- Seeing as how Alpha ( & Proxima ) Centauri is just a hoot 'n holler away from us on a cosmic scale, if there are planets there, IF they're habitable, if they're inhabited by sentient / sapient beings, etc., they must not possess telecommunications systems yet. Maybe some nearby stars with planets possessing sentient / sapient life are still at the equivalent of our early Industrial Age, at maximum. Has anyone thought of that ?

Or they could still be hunter - gatherers, or Bronze / Iron Age technological level.

[cat callahan]

Consciousness is the great filter. It is what we have been TOLD or Taught is there or not there-and so we miss or dismiss anything that might catch our attention. I have written 2 books on UFOs(under my real name) and have studied this for 30+ years. I have talked to Ivy-League educated scientists, engineers, and average folks who believe they have been contacted, yet are not allowed ANY physical evidence-WHY? Because wwe are a warring group! Look at the military adventurism of the Bush Administration! Would you want George Bush trying to assert power in YOUR part of the Universe? We are not yet ready to be allowed out into the solar system. But we are changing slowly!