Tag Archives: Enrico Fermi

Dinosaurs in the Cosmos 1: Enrico & Frank

by Shane L. Larson

shaneRockOne of the most profound consequences of the development of life on Earth is that the Cosmos has produced complex systems with the ability to question their own existence.  We are each of us a collection of atoms that the Universe has stirred together in such a way that we can contemplate the nature of the Cosmos itself. It is remarkable, really.  A rock is also a collection of atoms that the Universe has stirred together, but if a rock contemplates the Cosmos, I have no strong notion of what its rocky thoughts might be.  Humans, on the other hand, have been given a remarkable gift: we can ask questions, and then we can figure out the answers.  This game of questions and answers has a name.  We call it science.

Deep sea anglerfish (Monterey Bay Aquarium, E. Widder/ORCA).

Deep sea anglerfish (Monterey Bay Aquarium, E. Widder/ORCA).

There are many questions that we could use the atomic computing engine between our ears to consider, like: how can we grow enough food to feed 10 billion people? will a catastrophic shift in the San Andreas Fault change the geography of California? can I make a jetpack safe enough for sixth-graders to fly to school? anglerfish — what are they all about? why do some tissues develop cancer in the human body and others don’t?  Where did the Universe come from?

Questions about life and our own existence often dominate conversations in philosophy classrooms, research labs, and late nights around a campfire.  What is the origin of life?  Is there life elsewhere?  Is there intelligent life (on this planet or others)? These are BIG THOUGHTS — heady questions that have been asked for as long as we have been capable of asking them.  Some of them may have answers that can be figured out, and some of them may not.  Let’s think about one of these together — is there life elsewhere?  This is a question that could be answered by simply looking.  Except that looking for life elsewhere is difficult for two reasons: (1) Everywhere else is far away (as I’ve talked about before!) (2) We’re not even sure what life elsewhere might look like! We’re still discovering new life on Earth (like under the Antarctic ice, and even in the deep forests where humans have not tread before).

These points are hindrances to be sure, but that is the nature of this game. Our atomic computing engines are very good at facing down such adversity, and finding ways to answer our questions irrespective of the difficulties we face.  For big questions, it is often useful to make an estimate of what the answer could be before you embark on your quest for knowledge. This helps define the boundaries of your quest.  One of the defining traits of modern scientists is their ability to make quick, quantitative statements about extremely complex questions using only a few pieces of data that almost everyone agrees upon.  These kinds of problems often go by the name “back of the envelope calculations” because they are supposed to be simple enough as to fit on the back of an old bill envelope (though sometimes you may need a manila envelope).  They are often called Fermi Problems, after Enrico Fermi who was famous for this skill.

Enrico Fermi.

Enrico Fermi.

Enrico Fermi was born in 1901 in Rome; he rose to prominence in physics very quickly, completing his laurea (the equivalent of a Ph.D.) at the age of 21. He worked in Italy until 1938, when the Fascist regime passed the leggi razziali (“racial laws”), which threatened his wife Laura, who was Jewish. That same year, he was awarded the Nobel Prize in physics, and after acceptance in Stockholm, took his family to New York, where they applied to become residents of the United States. He famously worked on the world’s first nuclear reactor (“Chicago Pile-1”), and the Manhattan Project.

Fermi was, without a doubt, one of the giants of modern physics. When you first start studying physics, you are regaled with tales of the great minds of physics — their accomplishments as kids, their discoveries early in their careers, and the myriad ways they have transformed the way we view the world. As a young and aspiring physicist, it is incredibly intimidating and almost crippling; fortunately, I had many outstanding mentors. Each of them played a role in calming my doubts and fears; each of them helped me look at great scientists like Fermi and learn something about how to do science from their examples.

One of those things is Fermi problems. Fermi was famous for his ability to quickly estimate the answers to complicated problems. When his answers were checked against precise calculations, his results were amazingly close to the “real” answer! One of the most famous examples was Fermi’s estimate of the strength of the atomic explosion at the Trinity test. Fermi dropped handfuls of paper from a height of 6 feet before, during, and after the blast wave washed over the observation post. Based on the distance the paper spread as it fell, Fermi estimated the explosion to be the equivalent of 10,000 tons of TNT; the strength reported after the test had been fully analyzed was 20,000 tons of TNT.

The Trinity fireball, 16 milliseconds after the first human-made atomic explosion. Fermi was the first person to estimate the energy in the explosion.

The Trinity fireball, 16 milliseconds after the first human-made atomic explosion. Fermi was the first person to estimate the energy in the explosion.

Calculating the yield of an atomic bomb is definitely a big physics problem; it’s not the kind of thing most of us have to do in our lives. But all of us do Fermi problems every day. Every one of us. Things like: you’re going to watch curling with 4 other friends; how many pizzas should you order? how many bikes can fit in your garage with everything else? what time do you need to leave home to make it to work on time?

The classic problem that Fermi used to introduce this estimation concept is “how many piano tuners are there in your city?”  With Google, or the yellow pages (if you are a caveman), this question could easily be answered definitively.  But it can also be calculated by using some things you know or can estimate from your own personal experience.  Let’s try this together — I’ll do it for Logan, Utah, and you do it for wherever you happen to be right now.

The number of piano tuners in a given city is not general knowledge that most of us carry around. Despite its seemingly esoteric nature, it is a number that can easily be estimate to high accuracy using Fermi estimation methods!

The number of piano tuners in a given city is not general knowledge that most of us carry around. Despite its seemingly esoteric nature, it is a number that can easily be estimate to high accuracy using Fermi estimation methods!

The method is to ask a series of questions upon which the answer must depend, and that you may know the answers to. Questions like: how many people live in your city? how many households are there? how many households have pianos? How often do they tune pianos?  if you are a piano tuner, how many days a year do you work? how many tunings can you do in one day?  The answers to these questions don’t need to be 100% correct, nor do all of them have to be the same as someone else would guess.  All in all, the guessing and errors average out to give about the same answer for everyone.  This is a beautiful and elegant method of trying to understand the nature of the world by relying on the fact that your knowledge sometimes does better and sometimes does worse than reality, but overall combines to give something close to the truth.  In the figure below, I show the calculation for Logan, Utah. If I check the answer in my phone book, I find that I was pretty close!

Estimating the number of piano tuners in a city. Starting at the top, there is a simple series of numbers you need to estimate, most of which you probably know or can guess.

Estimating the number of piano tuners in a city. Starting at the top, there is a simple series of numbers you need to estimate, most of which you probably know or can guess. (Click to embiggenate)

The key methods to bear in mind in your quest to become a good Fermi problem estimator are:

  • Most problems seem unanswerable when posited, but usually can be broken down into simpler bits which you do know the answer to.
  • Rely on numbers you know the value of, or can estimate a reasonable value for.
  • Don’t worry about being precise!
  • Round relentlessly (“7 is about 10”)
  • Combine numbers sloppily (“15 x 6 is about 100”)
  • Use everyday experience as averages (“a human masses about 70 kg”)

This is a powerful and robust technique for answering questions. More to the point, you do this every day when you figure out how many cupcakes to make when the cousins are visiting, or when you buy rope to make a new tire swing, or when decide how long before the football game to start mowing the lawn to make sure you are done on time.  You could do it for all kinds of other things that may be important in your life and business, like: estimating how much pizza is consumed on a nearby college campus every day, or how many ball point pens are sold in your city each year, or how many car crashes there are in town each month.

Frank Drake.

Frank Drake.

For our purposes here, we are going to use this powerful technique to figure out how much life there might be elsewhere in the Cosmos.  One of the first people to think about this was astronomer Frank Drake. Drake was a radio astronomer, and made important discoveries regarding the nature of Jupiter’s magnetosphere, and in pulsar astrophysics. In the 1960’s he also began to think about how radio astronomy could be used to search for transmissions from extraterrestrial civilizations, initiating Project Ozma in 1960 to search for possibly intelligent transmissions from the nearby Sun-like stars, Tau Ceti and Epsilon Eridani.

When thinking about life in the Cosmos, and whether we are alone or members of a vast chorus of civilizations spanning the galaxy, Drake asked a specific (but plausibly unanswerable) question: how many civilizations might exist in the galaxy that we could communicate with?  The Fermi problem solution to this question is known as The Drake Equation.  We’ll examine the Drake equation and its implications next time.

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This is the first of two parts. The second part can be read here.

This particular piece was completed while in residence at the Aspen Center for Physics.

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Cosmos 2: One Voice in the Cosmic Fugue

by Shane L. Larson

imaginationHumanity is simultaneously blessed and cursed with one of the most ingenious creations of Nature: our imaginations.  Our brains have developed not just to run our bodies, and not just to absorb sensory data from the world. They store all the vast myriad of experiences we have and then, at a later time, recall that data for the express purpose of inventing ideas that may or may not have anything to do with reality.

An excellent example of how your brain works can be found in a simple game my daughter and I play at restaurants while we’re waiting for our food.  We call it “The Napkin Game.”  One person draws a simple line doodle, without lifting the pen, then the other person takes that doodle, looks at it from all angles, then adds more lines to turn it into a picture. When you draw a doodle for your partner, you don’t a priori know what it will be turned into.  That’s the magic of brains! Any random doodle could be Batman’s cowl, or a Wonka Bar, or a turtle. Your brain takes a little bit of visual input, maps it onto one of the trillions of neural connections in your mind, and makes something new!

An example of the Napkin Game. One person draws a simple line doodle, and the other person adds to it to make a picture.

An example of the Napkin Game. One person draws a simple line doodle, and the other person adds to it to make a picture.

One of the most important things your imagination does, is it extrapolates into the future.  Sometimes it makes up extrapolations out of whole cloth that likely have little bearing on reality (though they may be perfectly entertaining, if not desirable, daydreams).  I count among such extrapolations imagined futures where zombies have taken over the world, Apple Slice has made a comeback, or I am close personal friends with Queen Elsa of Arendelle.  But very often, the extrapolations are really simulations — attempts to divine a realistic future. This is the origin of wonder, of anticipation and excitement, and also of fear (particularly fear of the unknown). Imagination uses both of these extrapolations in the game we call science.

The most remarkable thing about imagination is that it knows no boundaries. T-rex flying a fighter jet? No problem. I’m really Walter Mitty, a member of MI:6 who cleans up after Bond?  Duh. Every kind of particle we have ever seen maybe has an undetected and completely made up “super-symmetric” partner particle?  Sure, that sounds cool to think about! 

Examples of imagination, possibly run amok. (L) Dinosaurs flying fighter jets [Lego model; dino added by S. Larson]. (C) The Standard model of particle physics. (R) The "SuperSymmetric" addition to particle physics, imagined by some physicists.

Examples of imagination, possibly run amok. (L) Dinosaurs flying fighter jets [Lego model; dino added by S. Larson]. (C) The Standard model of particle physics. (R) The “SuperSymmetric” addition to particle physics, imagined by some physicists.

Unfettered by physical limitations or abstract societal rules, our imaginations can stray from the possible to the impossible, from the real to the unreal, and from the mundane to the extreme. The most powerful aspect of this ability is that it allows us to ask questions about things of which we currently are completely ignorant.

Consider the question of life in the Cosmos.  Is there life elsewhere? Are we a singular instance of life, or is there a vast froth of life-filled worlds filling the deep, deep dark of the Universe?

One dish in the Very Large Array (VLA) near Socorro, NM. [image by S. Larson]

One lonely dish in the Very Large Array (VLA) near Socorro, NM, staring out into the Cosmos. [image by S. Larson]

It is a deep and through provoking question that has profound implications for our philosophical and cultural identities. We can ponder such questions precisely because our brains can take the question and push it to the extreme boundaries, which are:

(1) The Earth is unique. We are a singular instance of the music we call life, a lone voice shouting vainly into the vast, dark cathedral of the stars.

(2) The Cosmos is teeming with life, a vast ecosystem of atoms that have organized into patterns capable of replicating and contemplating their own existence.

Arthur C ClarkArthur C. Clarke once famously summarized these extremes, saying “Two possibilities exist: either we are alone in the Universe or we are not. Both are equally terrifying.”  The amount we are terrified by this thought is the fault of our imaginations.  We are inherently social creatures — we thrive on contact, discussion, and shared common experience. All of us have, at some point in our lives, experienced profound loneliness — being lost, being trapped, being left out by our peers. When we imagine being alone in the Cosmos, our brain magnifies that sense of loneliness a trillion-fold.  What gets simulated is not the Earth all alone, but ourselves all alone — what if I were alone in the Cosmos, lost in the vast dark? We anthropomorphize the entire human race, mapping our own personal feelings onto 7 billion other souls.

In the opposite case, our imagination proposes a Cosmos completely contrary to the normal hubris that humanity wields.  Despite our proclaimed belief in the fundamental tenets of Copernican astronomy, where the Earth is not the Center of All That Is, we certainly don’t lead our lives that way. Humanity, as a rule, does not pretend to be anything other than the Center of Everything!  But it could be that we inhabit a Cosmos with other intelligences, some perhaps vastly greater than our own, some perhaps implacable and as unaware of us as we might be of ants or bacteria.  Such musings are disquieting because they challenge the central tenet of our perceived existence as the premiere lifeform, on planet Earth or anywhere else.

The question of whether the Cosmos harbors life elsewhere is a compelling one from the perspective of our psychology, but also because there is an apparent conflict between two eminently reasonably scientific viewpoints.  The first of these viewpoints is the so called “Principle of Mediocrity.”  This is the no-holds barred manifestation of the Copernican Principle — there is nothing special about the Earth.  The Cosmos seems to be filled with planets (the latest count, as of today, 9 Dec 2013 is 1051 known planets (visit the Exoplanet Encyclopedia Catalog), with some 3000 candidates from the Kepler mission.  Our deepest probes of the Cosmos (the Hubble Extreme Deep Field) suggests there could be as many as 600 billion galaxies. If each galaxy has 300 billion stars, and every star has at least 1 planet (probably more) then there are a staggering number of possible worlds on which life could have arose. There is nothing special about Earth, so if life arose here, there should be no impediment to life arising on any of the trillions and trillions of other worlds that fill the Cosmos.

The Hubble Extreme Deep Field (XDF). [Credit: NASA; ESA; G. Illingworth, D. Magee, and P. Oesch, University of California, Santa Cruz; R. Bouwens, Leiden University; and the HUDF09 Team]

The Hubble Extreme Deep Field (XDF). [Credit: NASA; ESA; G. Illingworth, D. Magee, and P. Oesch, University of California, Santa Cruz; R. Bouwens, Leiden University; and the HUDF09 Team]

Enrico FermiThe opposing viewpoint is something called “The Fermi Paradox.”  It was originally proposed by Enrico Fermi, and can succinctly be summarized as, “Where are they?”  What Fermi wondered was why has the Earth, or any world in the solar system, not been visited by self-replicating robotic explorers of some distant alien race?  His point was that if we really want to explore the galaxy, the most efficient way to do that would be to send a robotic probe out to the nearest star.  It won’t get there in a human lifetime, but it will get there in a time substantially shorter than the age of the galaxy.  When the robot gets to a star system, it pokes around a bit, then builds 10 copies of itself using the natural resources it can find, and sends those copies out to the next 10 closest stars.  If every robot successfully makes 10 copies of itself, it only takes 11 replication cycles before there is 1 robot for every star in the galaxy.  But really, why would they stop there? They would just keep replicating until there are a whole lot of robots in the galaxy.  But we haven’t seen one yet!  Why not? One’s immediate gut reaction might be to think, “Well humans are just the first species to have such a crazy idea. The galaxy is not full of self-replicating robots because we haven’t built them yet!”  But if we apply the Copernican Principle to Earth and humanity in particular, there is no reason to believe we are the first instantiation of intelligent life; some civilization should have preceeded us, and built the fleet of galaxy filling robots.  But there are no robots, and the chance that we are the first civilization in the entire galaxy is vanishingly small.  The fact that there are no robots means that we are alone in the Cosmos. 

Why has our solar system not been visited by alien robots, sailing through to see what the galaxy is full of? This is the central tenet of the Fermi Paradox. [Model by S. Larson]

Why has our solar system not been visited by alien robots, sailing through to see what the galaxy is full of? This is the central tenet of the Fermi Paradox. [Model by S. Larson]

The space in between these two possibilities is a matter of intense debate among aficionados of the search for extraterrestrial life, as well as professional scientists who spend their careers thinking about this. There are as many facets of the debate as there are persons engaged in the discussion!  In the absence of true, reliable knowledge, our imaginations have free reign. We imagine every idea we can, then argue about whether the idea is plausible or even possible.  One of the most intriguing ideas in this space is that perhaps no civilization ever survives to build a self-replicating army of robots to explore the galaxy. Maybe the Cosmic fugue of life never grows beyond the initial swelling notes of the song.

The dinosaurs haven't (didn't?) go exploring the galaxy. [Image from Captain Raptor and the Moon Mystery, by O'Malley and O'Brien]

The dinosaurs haven’t gone (didn’t go?) exploring the galaxy. [Image from Captain Raptor and the Moon Mystery, by O’Malley and O’Brien]

This is not an unreasonable idea. Even if we confine our considerations to the history of life on Earth, we’ve seen “civilizations” that persist for long periods of time. The dinosaurs existed on Earth for 160 Million years, and never developed a single bit of technology (so far as we know), let alone build a self-replicating robot to proclaim their existence to the Cosmos. In the end, the dinosaurs were completely obliterated, wiped off the face of the Earth by an asteroid. Today, their closest living descendants are the birds, but no chicken has reached out to explore the Cosmos either. 

But we don’t even have to think about lifeforms long gone. Even among our own species, entire civilizations have utterly vanished from the world.  Five thousand years ago, the Indus Valley Civilization (IVC) was comprised of 5 million persons, fully 10% of the entire world population at that time. It stretched all along the Indus River valley, in what is today the borderlands between modern India, Afghanistan and Pakistan. The preeminent civilization of the era, the IVC developed the first system of weights and measures; quantitative measure is the foundation of all technology and science.  But they did not colonize the galaxy. The civilization survived for almost two millennia, until the cities were mysteriously abandoned and the civilization collapsed, never having once cast their voice out into the Cosmos. Before they had the ability to build a robot, drought and shifting economics with other, nearby civilizations destroyed the greatest civilization the world had known to that time.

If I were to take these two examples at face value, and use my imagination to extrapolate to other worlds, I might imagine that life is common throughout the Universe, but perhaps it is far too fragile a form of matter to survive. Perhaps it is always obliterated, by the abusive hand of the Cosmos or through ignorance and self-destruction. Obliterated before it can send its seed, robotic messengers, out into the Cosmos.  That would be a depressing thought, with terrifying implications for our future on this world. But it is not inconceivable (even knowing what that word means); even in my lifetime, the spectre of the destruction of our world has constantly loomed, though it has been an evolving chorus of spectres, each sharing the lead.  As a child growing up in the 1980s, the possibility of nuclear annihilation was real and forefront in our minds, even as children. The threat is perhaps no less real today, but the end of the Cold War has reduced the threat in people’s imaginations. Today, the fragility of our climate and environment plays a more prominent role in considerations of what our future may be. Now, as in The Cold War, the conversation is driven by ideology and arguments built around emotional viewpoints rather than scientific considerations. It is not clear we will survive to build a robot army that will explore the galaxy. 

The Earth as seen from Saturn.  Can you tell there might be life there from this picture?

The Earth as seen from Saturn. Can you tell there might be life there from this picture?

Another possibility is that maybe it is just too hard to find other life.  Maybe it is out there, but detecting it is far more difficult than finding the proverbial needle in a haystack.  We are not even sure if there is life elsewhere in the solar system, and we live here! What would an alien robot sailing into the solar system find?  There are almost 100 known worlds in the solar system that are at least large enough to be round (say larger than 200km; list at Wikipedia). Would a robot explore all of them, or simply gaze from afar?  Consider what the Earth looks like from beyond Saturn.  Can you tell there is life here?  Look at the Earth from the Moon.  Can you tell there is life here, especially compared to a picture of Titan from roughly the same distance?  What if the probe never came in this close, landing on the first world it encountered, say Neptune’s enigmatic moon Nereid? 

The Earth (L) and Titan (R), each viewed by a spacecraft from roughly the same distance.  Can you tell if either harbors life?

The Earth (L) and Titan (R), each viewed by a spacecraft from roughly the same distance. Can you tell if either harbors life?

Despite all the difficulties, real and imagined, of searching for life elsewhere, we continue to do it, both by sifting the surfaces of worlds near Earth, as well as plumbing the depths of interstellar space looking for messages from other beings.  The idea of there being life elsewhere is one that is hard to let go of, because the alternative is far too depressing — that we truly are alone. It is a staggering thought, which we are constantly reminded of.

There is a very famous picture of Earth, taken by Michael Collins during the Apollo 11 flight.  As the ascent stage of the Lunar Module Eagle returned to dock with Collins aboard the Columbia in lunar orbit, he snapped a picture showing the Eagle (containing Aldrin and Amrstrong) hanging in front of the magnificent desolation of the Moon, with the partially illuminated Earth in the background.  Collins later remarked,  “I remember most vividly the picture of the lunar horizon and then the LEM ascent stage in the foreground with these two guys in it, and then the Earth popping up at that instant… You’ve got 3 billion people over there, two people here and that’s it.” 

A picture from Apollo 11 of every human being, alive or dead, except for Michael Collins (the photographer).  [NASA Image AS11-44-6642]

A picture from Apollo 11 of every human being, alive or dead, except for Michael Collins (the photographer). [NASA Image AS11-44-6642]

It is perhaps one of the most poignant images of the lonely Cosmos ever taken — every member of the human race, alive or dead, except the photographer. If indeed we are alone in the Cosmos, then that was everything, captured in a single frame, at a single moment in time.  Every voice in the Cosmic fugue, the chorus of life.

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This post is part of an ongoing series, celebrating the forthcoming science series, Cosmos: A Spacetime Odyssey by revisiting the themes of Carl Sagan’s classic series, Cosmos: A Personal Voyage.  The introductory post of the series, with links to all other posts may be found here:  http://wp.me/p19G0g-dE

Smartphones and the Enduring Silence of the Cosmos

by Shane L. Larson

We live in an age of global communication, where the world is tied together electronically in ways that could not have been imagined twenty years ago.  Today, you are linked to the world through your smartphone and laptop.  The global village is hung on an intricate web of cellular networks and wi-fi hotspots, allowing you to be in constant communication with millions of strangers.  In a world where tweeting your every move and Facebooking random snapshots of your life are often decried as technological monsters that supplant deep, meaningful relations, it is easy to forget that the growth of wireless connectivity empowers you to find and be exposed to diverse new ideas, awesome spectacles of nature and civilization, and amazing works of art.

The other day I stumbled on one such awesome spectacle: a fantastic YouTube video of Eric Clapton and Chuck Berry singing “Wee Wee Hours” (http://www.youtube.com/watch?v=mhNjQBsBPLY).  As a general rule, I avoid reading comments online for anything. The signal to noise ratio on the web is very low.  But I happened to notice that an astute commenter had asked, “Why isn’t this video on the space shuttle telling aliens how awesome we are?

I understand the sentiment; this is awesome stuff.  But as it turns out, we are beaming this spectacle into deep space for any unsuspecting extraterrestrial intelligence to stumble upon and realize how awesome we are.  Since the invention of radio, the growth in broadband electromagnetic communication on Earth has progressed as fast as we could build transmitter towers and sell radio and television receivers to a world population enamoured with gadgets.  Radio and television broadcasts are omnidirectional — the signals flood out on the airwaves in all directions so everyone in all directions can catch the broadcast.  This means that UP is just as probable as sideways, and our television and radio signals are streaming into outer space, a bright electromagnetic cacophony of modern entertainment that screams to the Cosmos “Hey! We’re down here!  There’s (intelligent?) life down here!” So Chuck and Eric are currently blasting their way out into the Cosmos; that performance was recorded in 1987, so the most distant point in the Cosmos that could be aware of this awesomeness is some 25 lightyears away.

As it turns out, Chuck is also rocketing out into space in other ways.  Voyager 1 and 2 both carried with them a Golden Record (http://voyager.jpl.nasa.gov/spacecraft/goldenrec.html) containing instructions on how to play the record, a map to find Earth, 116 images of life on Earth, audio greetings in 55 languages, and 90 minutes of music from the planet Earth, including “Johnny B. Goode” by Chuck Berry.  A single handwritten sentence is etched on each record, reading “To the makers of music — all worlds, all times.

So in some sense, Chuck Berry is plausibly our emissary to the first extraterrestrial intelligence we will encounter.  In the case of our expanding sphere of radio noise, he might be an unintentional emissary.  By contrast, the Voyager record is a highly intentional attempt to communicate with life beyond the Earth.  In many ways, the Voyager record embodies an almost unfathomable optimism about the chances of the record ever being found by anyone.  Ignoring the sheer vastness of the empty dark between the stars that Voyager 1 and 2 are plummeting into, what are the chances of there being someone out there to find them?

There is a very famous problem about extraterrestrials in the scientific community called the Fermi Paradox.  The way the Paradox was first described to me was poetic and majestic.  Enrico Fermi was strolling with friends through a starlit meadow one evening, hands plunged deep in his pockets and his feet shuffling through the burgeoning spring grass as he gazed skyward at the arch of stars.  He stopped, and with the casual aplomb that scientists are masters of says, “Why aren’t they here?”

Fermi’s point was that the galaxy is vast.  If life is common and plentiful, humans almost certainly are not the first lifeforms to arrive on the scene.  That means we should have been visited by extraterrestrial beings already, or perhaps more to the point, we should have received their radio broadcasts and their blues records!  Because we have not had such encounters, and because we have not received such signals, Fermi concluded that life is not plentiful in the galaxy, and in all likelihood, we are alone.

There have since been many arguments for and against Fermi’s conclusion, which brings me back to where we started. I watched this Chuck Berry and Eric Clapton video on my smartphone, connected to a low-power cellular network.  In today’s world, it is extremely common to carry in my pocket entertainment that was traditionally broadcast via television and radio.  We stream music and news over the network through CNN and services like iTunes and Pandora.  The age of massive radio signals that can reach the far sides of the Earth while simultaneously flooding out into space is being supplanted by the wireless grid.  The sphere of loud radio noise expanding away from Earth is beginning to taper off, and it is not beyond the boundary of possibilities that it may fade all together.  It is not unreasonable to imagine that in my and your lifetimes, Earth will become radio quiet, undetectable by intelligences other than our own.  By a similar token, maybe the aliens are out there, but they’ve gone radio quiet and beings from a distant blue world will never hear them either.

It is plausible that civilizations are only radio-bright for short periods of time until technology improves to the point that personal communication becomes portable and distributed in a planet-girdling web of fibers and low-power radio links.  If so, then we may not be alone in the Cosmos.  It may be that there are other civilizations, but they too are absorbed by wi-fi hotspots and alien cyber-cafes, looking forever inward and connected only to their own world through small screens and technology.

Just like us.

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NOTE: This piece arose because one of my friends pointed me at the Clapton/Berry video; I’m sorry, but I don’t remember who that was!  It was spurred onward by another friend when we floated the idea of a civilization going radio quiet with the growth of wi-fi (a known, suggested resolution of the Fermi Paradox that often goes by the moniker “the fiber optic objection”);  I can’t remember who that was either!  I must be losing it…