And ... the Great Silence persists: More on the Fermi Paradox: Where is Everyone?

Before diving into the Biggest Question - Are we alone in the universe? - I'm pleased to announce new volumes in my Out of Time series of novels for teen readers who love adventure laced with history, science and other cool stuff.

New books include Boondoggle by SF Legend Tom Easton & newcomer Torion Oey plus Raising the Roof by R. James Doyle! All new titles are released by Amazing Stories.

Meanwhile, Open Road republished the earlier five novels, including great tales by Nancy Kress, Sheila Finch, and Roger Allen. Plus The Archimedes Gambit and Storm's Eye!

The shared motif... teens from across time are pulled into the 24th Century and asked to use their unique skills to help a future that's in peril!  Past characters who get 'yanked' into tomorrow include a young Arthur Conan Doyle, Winston Churchill, Joan of Arc's page and maybe... you!

All of the Out of Time books can be accessed (and assessed) here. 

* With coming authors including SF legend Allen Steele and newcomer Robin Hansen.

And now to the Great Big Question.

== Because there's bugger-all (intelligence) down here on Earth! ==

In "A History of the Search for Extraterrestrial Intelligence," a cogent overview of 200+ years of SETI (in various forms), John Michael Godier starts by citing one of the great sages of our era and goes on to illuminate the abiding question: "Are we alone?" Godier is among the best of all science podcasters. 

I also highly recommend YouTube channels by Isaac Arthur and Anton Petrov as well as the PBS series EONS.

Joe Scott runs a popular Science and future YouTube Channel that is generally informative and entertaining. And much more popular than anything I do. This episode is divertingly about what the year 2100 might be like. 

== Anyone Out There? ==

Hmmm. Over the years, I’ve collected ‘fermis’ … or hypotheses to explain the absence of visible alien tech-civilizations. In fact, I was arguably the first to attempt an organized catalogue in my “Great Silence” paper in 1983, way-preceding popular use of ‘the Fermi Paradox.” 

See Isaac Arthur’s almost-thorough rundown of most of the current notions, including a few (e.g. water-land ratio) that I made up first. Still, new ones occasionally crop up. Even now!

Here’s one about an oxygen bottleneck: “"To create advanced technology, a species would likely require the capability to increase the temperature of the materials used in its production. Oxygen's role in enabling open-air combustion has been critical in the evolution of human technology, particularly in metallurgy. Exoplanets whose atmospheres contain less than 18% oxygen would likely not allow open-air combustion, suggesting a threshold that alien worlds must cross if life on them is to develop advanced technology." 

Hence my call to chemists out there!  Is it true that “an atmosphere with anything less than 18% oxygen would not allow open-air combustion”?  That assertion implies that only the most recent 500 million years of Earth history offered those conditions. And hence industrial civilization might be rare, even if life pervades the cosmos. 

My own response: It seems likely that vegetation on a lower-oxygen world would evolve in ways that are less fire resistant. After all, there is evidence of fires back in our own Carboniferous etc.

== This time the mania just isn't ebbing (sigh) ==

The latest US Government report on UFO/UAP phenomena finds – as expected – no plausible evidence that either elements of the government or anyone else on Earth has truly encountered aliens. 

Alas, it will convince none of the fervid believers, whose lifelong Hollywood indoctrination in Suspicion of Authority (SoA) is only reinforced by any denial! No matter how many intelligent and dedicated civil servants get pulled into these twice-per-decade manias. 

I don’t call this latest 'investigation' a waste of taxpayer money!  Millions wanted this and hence it was right to do it!  Even if none of those millions of True Believers will credit that anything but malign motives drive all those civil servants and fellow Americans.

Shame on you, Hollywood. For more on this, especially the SoA propaganda campaign that (when moderate) keeps us free and that (when toxically over-wrought) might kill our unique civilization. For more, see Vivid Tomorrows: Science Fiction and Hollywood.

…or my own highly unusual take on UAP phenomena. I promise fresh thoughts.

And here John Michael Godier offers an interesting riff on a possible explanation for the infamous WOW signal detected by a SETI program in 1977. 

== on the Frontier ==

Mining helium-3 on the Moon has been talked about forever—now a company will try. "There are so many investments that we could be making, but there are also Moonshots."

Yeah, yeah, sure. “Helium Three” (in Gothic letters?) is (I am 90% sure) one of the biggest scams to support the unjustifiable and silly “Artemis” rush to send US astronauts to perform another ritual footprint stunt on that useless plain of poison dust.  

Prove me wrong? Great?  I don’t mind some investment in robotic surveys.  But a larger chunk of $$$ should go to asteroids, where we know -absolutely – the real treasures lie.

Meanwhile, far more practically needed… and reminiscent of the very first chapter of my novel Existence…  Astroscale is one of several groups demonstrating methods to remove debris from Low Earth Orbit (LEO). Though we gotta hope that a desperate world ‘leader’ doesn’t decide to spasm wreck LEO, as his final gift to the world.

== Dive to the Sun! ==

The Parker Solar Probe – (the team named me an informal ‘mascot’ on account of my first novel) has discovered lots about how solar magnetic fields churn and merge and flow outward to snap and heat the solar corona to incredible temperatures.

(I am also a co-author on a longer range effort to plan swooping sailcraft, that plunge just past our star and then get propelled to incredible speed. The endeavor’s name? Project Sundiver! Stay (loosely) tuned.)

== Physics and Universal Fate ==

I well recall when physicists Freeman Dyson and Frank Tipler were competing for the informal title of “Theologian of the 20th Century” with their predictions for the ultimate fate of intelligent life. In a universe that would either 

(1) expand forever and eventually dissipate with the decay of all baryons, or else 

(2) fall back inward to a Big Crunch, offering Tipler a chance to envision a God era in the final million years, in his marvelous tome The Physics of Immortality.

 I never met Tipler. Freeman was a friend. In any event, it sure looks as if Freeman won the title. 

Only... how sure are we of the Great Dissipation? Its details and influences and evidence and boundary conditions? Those aspects have been in flux. This essay cogently summarizes the competing models and most recent evidence. Definitely only for the genuinely physics minded!

A final note about this. Roger Penrose - also a friend of mine - came up with a brilliant hybrid that unites the Endless Dissipation model and Tipler's Big Crunch. His Conformal Cosmology is simply wonderful. (I even made teensy contributions.) 

And if it ain't true... well... it oughta be!

And finally... shifting perspective: this ‘official’ Chinese world map has gotta be shared. Quite a dig on the Americas! Gotta admit it is fresh perspective. Like that view of the Pacific Ocean as nearly all of a visible earth globe.   A reminder how truly big Africa is, tho the projection inflates to left and right. And putting India in the center actually diminishes its size.

===

PS... Okay... ONE TEENSY POLITICAL POINT?

When they justify their cult's all-out war against science and every single fact-centered profession - (including the US military officer corps) - one of the magical incantations yammered by Foxites concerns the Appeal- to-Authority Fallacy.

Oh sure, we should all look up and scan posted lists and definitions of the myriad logical fallacies that are misused in arguments even by very intelligent folks. (And overcoming them is one reason why law procedures can get tediously exacting.) Furthermore, Appeal to Authority is one of them. Indeed, citing Aristotle instead of doing experiments held back science for 2000 years!

Still, step back and notice how it is now used to discredit and deter anyone from citing facts determined by scientists and other experts, through vetted, peer-reviewed and heavily scrutinized validation. 

Sure. "Do your own research' if you like. Come with me on a boat to measure Ocean Acidification*, for example! With cash wager stakes on the line. But for most of us, most of the time, it is about comparing credibility of those out there who claim to deliver facts. And yes, bona fide scientists with good reputations are where any such process should start, and not cable TV yammer-heads. 

The way to avoid "Appeal to Authority" falacy is not to reflexively discredit 'authorities,' but to INTERROGATE authorities with sincerely curious questions... and to interrogate their rivals. Ideally back and forth in reciprocally competitive criticism. But with the proviso that maybe someone who has studied a topic all her life may, actually know something that you don't.

*Ocean acidification all by itself utterly proves CO2-driven climate change is a lethal threat to our kids.  And I invite those wager stakes!

Are we about to corner Fermi? The Paradox explained?

== Recent excitement ==

The best year for human space exploration since 1972 only keeps getting better.  For example…

Pluto is getting weirder. Smooth craterless plains. Regions cracked like drying mud on a giant scale. Atmosphere extends over 1000 miles from the surface. Visible wind-streaks on the surface, which may sites of current active cryo-venting.  And it's losing it's atmosphere to space at 500 tonnes/hr. Forming a dense ion tail trailing away from the sun.  Uh oh. Pluto may be demoted from Dwarf to Comet. (Thanks Pau451:)

And another coolness: The “Gore Sat” – a scientific spaceprobe proposed originally by Vice President Al Gore – is now positioned in a gravitationally metastable orbit about a million miles from Earth, closer to the Sun, allowing it to send home stunning images of the entire lit face of our planet, every single day or hour. Of course the money was spent for science. Discovr was launched in February of this year on a mission to monitor solar winds. Keeping tabs on space weather helps scientists issue accurate warnings ahead of solar storms that can potentially disrupt telecommunications or power infrastructure. But Gore (whose Senate bill around 1990 freed the internet into the wild and open thing we know) also dreamed that the perfect images of our world might inspire us.  Make it so.

= Your “Fermi” theory of the month ==

I’ve been asked to rebuild my catalogue of possible explanations for the Fermi Paradox… or the mystery of why we see no signs of technological civilization out there, despite extensive searches. Well well. I’ve been in this field for more than 30 years, both as an astronomer and an author of sf’nal thought experiments about alien life. (See a compilation of my writings here. Also see this animated introduction to the Fermi Paradox. A bit simplistic and off by a few factors. But interesting.)

That catalogue? Well, I started building it in 1981. I estimate close to a hundred hypotheses that are at least “not impossible,” with two dozen or so qualifying as “plausible” contributors to the observed scarcity of high-tech ETs… and maybe five or six that seem rather compelling. But let’s start with one that sits squarely in the mid-range.

They are out there, but sparse enough that we just haven’t spotted them yet!  We simply need to look a little harder.

And indeed.  It seems that is what we are about to do.

== SETI goes big in 2015 ==

Yuri Milner and Stephen Hawking have just announced a $100 Million Breakthrough Initiative to reinvigorate the search for intelligent life in the universe over the next ten years. “Also present at the Royal Society in London for the project's announcement earlier today were Astronomer Royal Martin Rees, SETI Pioneer and UCSC Professor Emeritus Frank Drake, UC Berkeley Professor Geoff Marcy, Breakthrough Prize Foundation Chair Pete Worden, renowned author and producer Ann Druyan, and UC Berkeley postdoctoral fellow Andrew Siemion.” 

Notable, several of the members of this initiative, Geoff Marcy, Dan Werthimer and Andrew Siemion, have worked with me in endeavors to prevent METI or rash message beaming outward -- yoohoo shouting for attention from extraterrestrials.  

This new B.I. endeavor will include public engagement about messages! But there is no intent to actually send any, before the extensive discussions and examination-of-issues that many of us have long requested. I hope they will hold true to this promise.

This will be the biggest scientific search yet for signs of intelligent life beyond Earth. The Breakthrough Initiative includes significant access to two powerful radio telescopes – the 100-meter diameter Green Bank Telescope in West Virginia, and the 64-meter Parkes Telescope in Australia. There will also be significant efforts in Optical SETI.  Lick Observatory's Automated Planet Finder (APF) Telescope above San Jose CA will undertake a new deep and broad search for optical laser transmissions from nearby civilizations, if any exist.

You can tell they want to move vigorously on this from the fact that they hired Pete Worden to run the enterprise. The funds provider is Yuri Milner, a Russian entrepreneur and investor who has made a fortune in Silicon Valley. The program will include a survey of the 1,000,000 closest stars to Earth. It will be 50 times more sensitive than previous SETI research, will cover 10 times more of the sky, and will scan at least 5 times more of the radio spectrum – and 100 times faster. I’m hoping they will collaboratively make use of lessons learned by Jill Tarter and others at California’s SETI Institute.  Here is a well-written appraisal in the Economist.

Happy hunting guys. Just follow the protocols, please.

== Another “Fermi” for the catalogue? ==

I keep hearing this one… that we see no evidence of alien civilizations because they are indifferent to us.  Their technologies and communication methods are so far beyond us that we mistake them for natural phenomena, and they have as little interest in us as we might have in a hive of termites.

It has a nice, round smoothness to it, and aggressive humbleness is very much in vogue, these days. Still, the indifference explanation strikes me as much less likely than it at first seems.  Might we be "like ants" to some super species?  Sure! 

But we assign experts to study ants with passionate interest.

The response to that? "There are millions of ant nests for every ant scientist. Hence we aren’t likely to be one of the nests getting attention!"

Clever. But that response fails on two counts:

1) Even if you crank every Drake Equation factor to maximum, the very highest number of new tech-races to emerge in the galaxy would be maybe one per year. One… per year… across the whole Milky Way. Hence, such each new tech race is a noteworthy event when it happens. It’s not comparable to the zillions of ant nests per human. The scaling is entirely different.

2) Super beings will be able to create and deputize sub-agents at any level of intelligence or programmed interest.  It would be both reasonable and very cheap for them to assign such deputies to investigate and communicate with each newborn "ant" tech race, like ourselves. 

Oh, you can pose dozens of reasons why they might not choose to do that! But now you are talking cultural motivations and notice this: that you assume all the super-duper advanced races will be similarly incurious and indifferent! That, in turn, relies upon the number of uber-civilizations being very small!  Because if such civilizations are both numerous and diverse, then one or another or many will be interested, after all, in "ants."

Can you see why this field is actually a whole lot more subtle than our surface impulses imply?  The temptation seems natural to shout "of course THIS is the answer!"... but it can be silly, when confronting a vast and complex/mysterious cosmos.

Indeed, it is the surest sign of an immature and intemperate mind, to declare that, based on almost not evidence: "I know the answer!"

And now... some cool space-related miscellany.

== We need rapid advancement in space… to save Earth! ==

Many people are aware that the Sun has an eleven (actually 22) year cycle of sunspot and magnetic field activity.  There appear also to be longer cycles having to do with deeper convection layers. Now an interesting hypothesis with a new model that “predicts that the pair of waves become increasingly offset during Cycle 25, which peaks in 2022. During Cycle 26, which covers the decade from 2030-2040, the two waves will become exactly out of synch and this will cause a significant reduction in solar activity.” And “When they are out of phase, we have solar minimums. When there is full phase separation, we have the conditions last seen during the Maunder minimum, 370 years ago."

Suggesting that the 2030s might feature an activity dip that could counter a bit of global warming. We had better have IQ boost pills by then, or the Fox-denialist cultists will have a field day. Oh, but by then the vested interest oligarchs will be Big Sustainables.

So how to verify any of this? Fund research back at levels almost a quarter as high as they were in the 1950s and 1960s, that’s how!

Alas, at present , scientists do not have any way to view the sun that is not facing earth. This capacity existing across some years in the past. (Especially when the denizens of Counter-Earth were willing to cooperate.) Now? Well, we make our other robots take on even greater workloads. Lately, the Curiosity rover’s Mastcam has captured images of the sunspots of the side of the sun that is pointed away from earth, offering more continuity of record for major suspot regions.  "One sunspot or cluster that rotated out of Curiosity's view over the July 4 weekend showed up by July 7 as a source area of a solar eruption observed by NASA's Earth-orbiting Solar Dynamics Observatory", said NASA.  

== Space Miscellany! ==

What If We Can Never Travel Faster than the Speed of Light? I don’t credit every part of this scenario but it is vivid and fun.  And it demonstrates a basic truth… that the speed of light only makes interstellar colonization difficult, not impossible.  

This article on alien planetary systems misses the selection effect… that the Kepler probe’s method for discovering distant systems is extremely biased toward discovering planets orbiting close to their suns.  But bear that in mind and read it anyway.

One analysis shows the planet HIP11915b to be a close match to Jupiter both in mass and orbital period, and its host star is extraordinarily similar to the Sun. Beyond having fundamental physical properties close to the Sun, initial spectroscopic analysis suggests that HIP11915 is also a solar twin in the sense that its detailed abundance pattern matches the solar pattern (Melendez et al. 2015, in prep). The presence of a Jupiter twin and a solar-like composition both make HIP11915 an excellent prospect for future terrestrial planet searches."  

                                                                           

For those of you who still think we should make it a goal to “go back to the Moon,” instead of sensibly mining asteroids, this clear cartoon from SMBC.

The “dust” that is causing most of the absorption in interstellar space may be largely C60 buckeyballs.  Wow.   

                                                                                                                            

Are We Alone in the Cosmos, cursed by Fermi's Paradox?

And now the news from Alpha Centauri…

(Oh, I’ve waited for so long to utter those words! News. From Alpha Centauri. Wow!)

After an incredible decade, in which the number of planets known beyond our solar system increased from zero to several hundred, with a couple of thousand potential "hits" still to verify, astronomers have now detected a roughly Earth-sized world orbiting between the two stars nearest to our system, Alpha Centauri A and Alpha Centauri B.  Much too hot to sustain life, it nevertheless will help in narrowing down the search space for others.  Moreover, now we have a target for the first interstellar probes, which are already under discussion.  Indeed, the youngest of you readers may live to see them launched.

Ah, but this raises the perennial question.  If planets are more common than we ever thought, then what about life-worlds? And even alien intelligences?

I have been involved in this topic all my life, having grown up in Southern California, the part of human civilization least rooted in the familiar, traditional or... perhaps... sane.  I am best-known today as an author of novels and stories about our many possible-plausible futures, including some that explore a wide range of possible extraterrestrial civilizations. My scientific career, ranging from optics to astrophysics, led to papers about SETI in the 1980s that include what is still the only full review article in the field, compiling all then public theories for what I called The Great Silence, but that is now more widely known as the Fermi Paradox. 

(See a collection of articles and speculations about the Search for Extraterrestrial Intelligence (SETI).)

Today, we'll dive into the Fermi Paradox, in some detail. But first a little background.

The first time I witnessed the subject of extraterrestrial intelligence brought up in a scientific setting was at a Caltech physics colloquium in 1968, when I was just seventeen. The speaker remarked on the remote possibility that pulsars -- recently discovered radio sources that emitted bursts in perfect rhythm -- might turn out to be beacons of an advanced civilization. They were, after all, several thousand times more regular in their repetitive "beepings" than any other astronomical radio source ever discovered.

The speaker was only partly serious, though pulsars to this day are listed in catalogues with the prefix LGM -- a smiling reference to "Little Green Man." Despite that whimsy,  sides were quickly taken, and it was soon very clear that most of those with tenure didn't like this kind of talk at all.

But attitudes were changing rapidly during that decade -- the exciting era of Apollo moon landings and stunning pop music. A few years later some of those who seemed angriest in 1968 applauded loudly when Carl Sagan unveiled the gold plaque that was to be placed upon Pioneer 10, the first human artifact launched on a trajectory that would take it out of the solar system.

Today that plaque is famous, along with "messages" that followed on Pioneer 11 and the Voyager probes. They depict the nude figures of a woman and a man, an arm raised in greeting, a schematic of the planets of our system, and a rayed pattern of lines and binary dots representing the most prominent pulsars detectable from Earth. The pulsar map should enable any distant beings who recover the spacecraft to trace its point of origin within a light-year in space, and its launch date to within six months.  Oh, and the Voyager probes famously carry disks with recorded sounds and images of Earth. In fact, no scientist expects the messages to be recovered by aliens, though our own speedy descendants may collect Voyager for a museum.

Ever since the 1960s another, related project went through many ups and downs.  SETI programs (Search for Extraterrestrial Intelligence) prospered and withered under public excitement and ridicule, a cycle that continues even today... and that we may discuss another time. But let's stay focused.

Of course other-worlds and their inhabitants had already long been the topic of stories -- some great and others dismal -- on the pages of science fiction pulps of the thirties and forties, then more insightful thought experiments by Arthur C. Clarke, Ray Bradbury Robert Heinlein and others.  A tradition that extends through authors like C.J. Cherryh, Greg Bear and Dan Simmons all the way to more recent speculations about alien thought processes by Ken MacLeod and Iain Banks.

In fact, this tradition goes back much farther, to wanderers' tales like Journey to the West and the Odyssey. The expansion of our horizons of interest may be among the most human of all activities, as we stretch our gaze and curiosity beyond the mere present, the mere town, nation or even planet.  If we ever do encounter the alien, it can be hoped that the vast literature of science fiction gedankenexperiments (thought experiments) about contact will be consulted by our wisest sages, who will be amazed and enlightened by the vast range of possibilities we humans have already imagined.

== The Essential Questions About Alien Life ==

The Fermi Paradox refers to a question posed by the great physicist Enrico Fermi in the 1940s, demanding: "If it seems so likely the universe may host other life forms, how come we haven't seen any signs?"  Not just of radio beacons, but of mighty structures that our own descendants might someday build out there in space. Or leakage from chatty commerce between civilizations.  Or indeed, any trace that the Earth was visited during the 2 billion years that it was "prime real estate" with an oxygen atmosphere, but nothing higher than slime molds to defend it.

It is a fascinating topic... perhaps the fascinating topic.  For it takes you from pondering the birth and death of stars and planets to the dynamics of atmospheres and the potential origins or life... to intelligence (what is it and how many varieties can it come in?)... all the way to the stark possibility that few technological species survive their tense adolescence, attempting to cross a minefield of potentially lethal errors, from nuclear war or designer plagues to ecological devastation or cultural stagnation...

... all of which I talk about in my most recent novel, EXISTENCE.   In ways that I hope readers find both fascinating and thrilling, embedded in an exciting, near-future plot  There's a new idea on almost every page.  And why not? I've been cataloguing the possibilities for what feels like eons.

== The Drake Equation ==

The most common tool that folks use, in appraising the Great Silence is a little gem called the Drake Equation (D.E.), concocted by the early SETI pioneer Frank Drake when he was at the Arecibo National Radio Observatory. It remains the most widely accepted tool for xenological speculation.

Let N = the current number of technological civilizations in the galaxy. Then,

N = R P n(e) f(1) f(i) f(c) L

Here R is the average rate of production of suitable stars since the formation of the galaxy, approximately one per year. (The current rate is slower. R is an average that includes the burst of star creation early in the galaxy's history.)  f(s) is the fraction of stars that are accompanied by stably orbiting planets. Factor n(e) is the average number of planets per system that have the requisite conditions to support life.

The other factors include f(1), the fraction of these congenial planets on which life actually occurs; f(i), the fraction of these on which "intelligence" appears; f(c), the fraction of intelligent species that attain technological civilizations, and L, the average lifespan of each species.

The D.E. certainly seems to line up the varied factors involved in bringing sapient life to prominence in our galaxy.  All the terms on the far left of the D.E. have to do with the prevalence of stable, reliable stars... and then how many have planets. There are plenty of stable, long-lived G-type dwarf stars like the Sun out there... about 6 percent of the galaxy's several hundred billion stars. Are there planets circling many of them? (We astronomers were always sure there were, for reasons of angular momentum that I won't go into here. We've grown a lot more confident in recent years! Though mysteries still abound.)

== The likelihood of life ==

What are the chances of life erupting spontaneously on isolated worlds? It appeared to do so swiftly on Earth, almost as soon as the planet cooled enough for oceans to form. Three scientific discoveries and one useful philosophical tool gave researchers the courage to make crude estimates about the distribution of life among the stars.

The first discovery came when it was found almost ridiculously easy to make amino acids, and other precursors to living matter, from abundant molecules such as methane, ammonia and cyanogen. Stanley Miller subjected a water solution of these substances to electrical discharge and ultraviolet radiation and got an organic "soup" in short order. Leslie Orgel of the Salk Institute accomplished the same thing by a freezing process. The high pressures of ice formation not only gave up amino acids, but the purine adenine as well. (Adenine is one of the four building blocks of DNA, and is the core of ATP, adenosine tri-phosphate, which controls the energy economy of the living cell.

So many mechanisms have been found that can change crude precursors into "biological" molecules that today organic activity seems almost an automatic consequence of the distribution of chemical elements in the universe.

The second major discovery supports this point of view. During the last two decades, radio astronomers -- listening to narrow emission lines from interstellar space -- have discovered great clouds of complex molecules: ethylene, formaldehyde, ethyl alcohol; some even claim evidence for -- you guessed it -- adenine. (Astronomer and science fiction author Sir Fred Hoyle, looking at starlight scattered from interstellar dust, even thought that the dust itself might actually be something akin to bacteria... living cells about a micron in size, in diffuse colonies spanning light-years and outmassing suns. It's an extravagant speculation, but fun to think about.)

It's clear, then, from basic chemistry and radio astronomy, that the basic materials for life are out there. What about the right environments? We have to assume, until we have reason to think otherwise, that complex life must grow and evolve to intelligence on planets orbiting stable stars. Are there other "nursery worlds" like the Earth? Or might ecosystems more likely be found under the ice coverings of "roofed worlds" like Europa and Enceledus, where life-giving heat rises from below and any denizens would never see the stars?

== The Role of Sapience ==

Assuming planets are common and life is not rare, then how do we explain the Fermi Paradox?  Well, some hold that the factor that's small -- that keeps the numbers down --if f(l), the likelihood that a planet will create an intelligent species.  After all, it appears to have happened just once in 4.5 billion years on Earth... though some question whether it has happened yet, on this planet, at all!

What about dolphins, apes, sea lions, crows, parrots... even prairie dogs and octopus, who now show signs of some linguistic ability and problem solving savvy?  They all seem to crowd under a "glass ceiling" that none has ever broken through (except us).  Could that represent some kind of law of nature, and might we be a fluke?

A separate question, that I explore in EXISTENCE and also in my Uplift Series of novels – (now being re-released in the UK in beautiful omnibus editions by Orbit Books) -- is whether we should start to help other species burst through that glass ceiling and join us, as fully sapient fellow citizens of a much broader and more diverse Earthly culture.  The end result, that I portray in Startide Rising and The Uplift War (both won the Hugo Award for best novel), is a much richer and wiser civilization.

But oh, the pain of the two centuries it might take, to get there.  Are we willing – and sure enough of our skill and compassion – to embark on such a journey? Would it be the height of hubris and arrogance? Or would it be the ultimate act of selfishness to reject this challenge? To say to such species “we made it to the level of art and literature and ideas and science… and we refuse to offer anybody else a hand!”

== The Minefield Ahead of Us ==

All of the factors in the Drake Equation that we've discussed so far are ones that might explain the Fermi Paradox by keeping down the numbers of intelligent beings who reach our level.  If any of those factors were responsible for the Great Silence, then that means the Big Filter lies behind us.  We are rare... but the galaxy lies open before us and nothing stands in our way!

Then come the grouches who insist that life and intelligence and good planets and all that must be abundant, but that the Filter lies ahead of us.  Remember the minefield of possible mistakes that a “smart” race might make, from nuclear war to eco-devastation? (I explore a much longer list in EXISTENCE.) With that long litany of potential failure modes in mind, these folks ask how long any technological species can survive that endless expanse of snake pits, quicksand and possible ways to commit suicide. All of which falls into the Drake Equation factor “L” or how long such a species can survive.

(As it turns out, Drake left out several possible factors, but I'll leave it as an exercise for the fanatics among you to read my astrophysical article about this.)

Suffice it to say that these two sides -- those who think the Filter lies behind us and those who cry "look out!" -- are in furious debate to this day.  And it may surprise you that the "grouches" include many in the SETI community, those looking the hardest with radio telescopes, who openly admit that they are searching for the exceptions who do not kill themselves.

Again, there is no topic like this one, so rife with mind-blowing possibilities... and so free of any data about actual alien life! And yet so prone to sudden, premature conclusions, in which smart people declare "I know the answer!" without a shred of supporting evidence.

And why not?  This is, after all, the greatest Rorsach Test... a mirror or ink blot on which we project our personalities and notions and worries about our own species... our own selves. (And if so, what does it say about me, that I am one of the few saying "wait! We don't know enough yet. Don't jettison any of the possibilities too soon. The universe may yet surprise us.)

Perhaps the most painless and entertaining way to learn more is probably on the pages of my novel (I promise).  But I'll supply plenty of other links for those who relish our most precious human gift ---

-- The wonder of curiosity.  The insatiable thirst to know about what we know... and to speculate about what we don't and to explore this vast realm. A topic we all find fascinating... and as-yet we understand so poorly.

David Brin

http://www.davidbrin.com

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