Nectar of the Gods - A Look at Fermi's Paradox
(Originally posted May 1, 2017 on Blogger)
Are we the only communicative, technologically-advanced species in the universe? It seems statistically improbable that we are. When we consider just how many stars are in each galaxy (100s of billions to a trillion), and how many galaxies are in the observable universe (~100 billion), and couple these figures with the possible number of planets (trillions); it becomes nearly impossible to imagine we're the only ones. Particularly when we factor in just how long the universe has existed. So there must be evidence that we're not alone. However, no such evidence has ever been detected to suggest that there are others out there (save for perhaps the WOW! signal). It's odd when one thinks about it in terms of shear numbers; odd in both peculiarity and in statistics. This oddity has come be known as Fermi's Paradox.
In this blog we'll discuss the possible reasons as to why we've not detected intelligent life beyond Earth.
When I make references to intelligent life or advanced species, I'll mean technologically-advanced species capable of radio communication and space flight. We'll make this distinction, because intelligence isn't a Hominidae-specific trait; just have a look at our or others' pets, the birds in the sky, the dolphins playing in the wake of boats at sea, or any host of other animals.
In my blog on climate change, I attempted to conceptualize geologic time as a backdrop from which to put human-scale climate shifts into meaningful context. Now let's consider a much grander timescale; that of cosmic time. We'll use it as a backdrop from which to put into context our place in the known universe, and contemplate whether or not we're alone in it, and if so, why.
Our universe is about 13.8 billion years old, give or take 21 million years. This estimate is given within context of the Lambda cold dark matter model of the universe. You can read more about the Lambda cold dark matter model in my short blog on cosmic shear. The age of 13.8 billion years has been arrived at by extrapolating the measured expansion rate of the universe back in time. This, along with the expected cooling time of the cosmic microwave background radiation (Bennet et al., 2013) correlate well to the ~13.8 billion year age.
13.8 billion years is inconceivable! But let's try to put that number into perspective: 13.8 billion seconds ago, Sir Francis Drake was busy planting a flag on a beach declaring the land for Queen Elizabeth I; much to the dismay of the the indigenous population of that land who had been there for 10s of thousands of years. That beach is part of what is today California. If you had 13.8 billion dollars and spent $100 per minute every day, 12 hours a day (you need to sleep), 365 days a year, it would take you over 525 years to spend it all (assuming you made zero interest on it). If time and money aren't good analogies, let's consider distance. 13.8 billion inches is the distance around Earth's equator... almost 9 times. When we start to think of 13.8 billion in terms of everyday things, it really does seem inconceivable!
Some astrophysicists have inferred that the chemistry of life may have formed shortly after the Big Bang (~13.8 billion years ago), when our universe was a mere 10-17 million years old (Loeb, 2014). If so, then let's consider this in context that galactic formation may have begun as far back as 200 million years just after the Big Bang (Bromm et al., 2011). Galaxies invariably host star systems with planets, many of which are within their respective star's habitable zone. Over 100 billion galaxies, trillions of planets, and well over 13 billion years for the seeds of life to take root. It seems quite possible for life to exist, or to have existed, elsewhere in our vast universe, and even within our own vast galaxy. There are countless stars that have existed longer than our Sun. There are stars that may have hosted planetary systems that have lived out their stellar lives even before our Sun was a mere billion years old (not including M or K class main sequence stars, or red or orange dwarf stars).
These first stars could have hosted planets upon which life evolved. That life could have evolved as early as a few hundred million years after the planets themselves formed (Dodd et al., 2017). Our planet formed only ~4.54 billion years ago, billions of years after the formation of countless other planets within our galaxy, and across the universe. In the 4.54 billion years Earth has existed, it has given rise to us. And though we modern humans (Homo sapiens) have only been around for a generous ~200,000 years, we've managed to become a space-faring, radio-transmitting intelligent species capable of contemplating everything we've discussed so far.
Let's imagine the fact that there are other planets that have been around twice—if not nearly three times—as long as our own. Surely at least one of them has given rise to an intelligent species. If not now, then perhaps at some point in the distant past. We'll get into this further soon.
Given the epic rate at which the Kepler mission has been discovering "habitable" exoplanets (read this blog if you'd like to see why I use quotes for "habitable"), it's no stretch of the imagination to imagine that many of these distant stars may have planets hosting intelligent species like, or more advanced than ourselves. This was the crux for the founding of SETI (Search for Extraterrestrial Intelligence). While we continue to search for the existence of extraterrestrial intelligent life, we continue to transmit evidence of our own existence just through our ubiquitous use of modern-day technology (cell phones, radio, television, etc).
While other civilizations (if they exist) may have had many thousands, if not millions or even billions of years head start, we've only become potentially detectable within the last ~100 years. We at long last became a 'blip' on the cosmic radar screen with the advent of wireless communication ('radio').
The outer shell of our expanding 'radio bubble' is not more than 100 light years across; minuscule compared to the 100,000 light-year span of our Milky Way. Even still, it is a fascinating fact to consider that our expanding little radio bubble has already passed through thousands of other star systems by now. And as Kepler has shown, this means our radio bubble has likely washed over hundreds, if not thousands of potentially-habitable planets as well. And though the information contained in our expanding radio bubble is now hopelessly diffuse at those great distances (no thanks to the inverse square law), it's still fascinating to know that we've essentially graced the surfaces of faraway planets, each with its own 'sunrises', each with the potential of being home to some form of life. No matter how primitive that life might be (if it exists), the thought is riveting.
Unless there is an advanced civilization within the shell of our radio bubble, the chances intelligent life knows we're here is slim to none. The Milky Way is ~100,000 light years across (~588 quadrillion miles), so our bubble has only permeated a tiny fraction of our galaxy. There are billions of other stars out there, many of which may host planets. And this is only within our own galaxy. Andromeda (galaxy) has a trillion stars, and it is only one of 100 billion other galaxies in the known universe.
But not being detectable because our radio transmissions have yet to travel far enough to be detected doesn't mean our planet can't be detected. We're able to detect atmospheres (crudely) on planets in star systems light years away. It's possible intelligent life has done the same, and has detected our planet, declaring it a potentially-habitable one at that. Perhaps they've already sent probes our way to investigate, traveling at significant fractions of the speed of light. Or, perhaps knowing this planet is potentially habitable, they make sure to go radio silent so as not to be detected themselves. Or, perhaps they don't exist at all. This is a fascinating, and perhaps sobering thought. Fascinating in that perhaps there exists some intelligent being out there who knows or at least sees potential that we're here; sobering in that maybe there isn't anything out there, and (so far) we're the only technologically-advanced beings around. Perhaps, Earth is the only planet in the galaxy that harbors life.
Statistics can be a very revealing form of math, or it can be the most fuzzy of maths. Nine times out of ten, statistics we hear in the media are just presented as fact without any source of how they were derived, or what they actually mean in context. In California years ago, felony crime spiked and the stats showed it. This was touted in the media rather recklessly. Turned out that spike in felony crime was due to the fact that the price of certain bicycles had gone up such that theft of that brand of bike was now considered a felony, when only a year earlier it was a misdemeanor. Theft totaling less than $100 was a misdemeanor, and anything over that is a felony (I don't recall the exact number). When the price of the bikes rose above the $100 threshold, felonies spiked, even though the theft rate remained the same. Sure, factually felonies had spiked, but the reality tells a much different story. Hence, we ought to always ask what stats mean when they're presented.
In the early 1960s astrophysicist Frank Drake came up with a probabilistic approach to determining how many technologically-advanced civilizations currently exist in the Milky Way galaxy. He wanted to come up with a number that statistically represented how many advanced civilizations we could expect to exist in the Milky Way. He formulated a simple equation that took astrophysical, biological, and sociological factors into consideration. It has since become known as the Drake equation.
The results from his equation ranged from 20 to 50,000,000 advanced civilizations in the Milky Way galaxy. His results varied so widely because he was working with some arbitrary factors; ie) number of planets out there. I'd qualify the Drake equation as 'fuzzy math'.
However, in the years since, the Kepler mission has given us a much better idea about exoplanet quantities. As such, we now have more meaningful numbers with which to substitute into the astrophysical portion of the equation. Additionally, there have been some tweaks made to the original equation to account for other factors not originally considered. However, even with all this, we're still no closer to coming up with an acceptable number than we were 50 years ago. Depending on what numbers are substituted into the equation, from the most conservative to the most liberal, results have varied by a factor of 100.
So astronomers Woodruff Sullivan and Adam Frank decided to approach the problem from a pessimistic angle. They did this by considering what it would mean for the biological and sociological factors in the Drake equation if we actually are the only technologically-advanced species in the entire known universe. Ugg, how depressing!
Assuming we're it, they calculated that for there to be just a 1% chance for us to be the only advanced species to have ever existed in the entire known universe, then the chance for each habitable planet within the universe to produce an advanced civilization like our own would have to be less than 1 in 400 billion trillion. That's:
1 : 4,000,000,000,000,000,000,000,000
400 billion trillion microseconds ago the universe didn't exist and wouldn't for billions of years! One in 400 billion trillion (400 septillion) is such an impossibly-remote chance that we must conclude we're not the only advanced species to have ever existed. Right? Or are the odds truly that astounding. I don't know. No one does. But, in a universe that likely contains trillions of habitable planets around stable, relatively long-lived stars, it seems to fly in the face of logic to conclude that we're all that is, has been, or will ever be.
So where is everyone? Here's where we'll get a bit philosophical. But fret not my friends; science was born out of philosophy, and philosophy is the offspring of curiosity; the very thing that drives us. That, and of course love.
- May the Odds be Ever in Our Favor -
Earth is incredibly unique for many reasons; We have a large moon which has slowed the planet's rate of rotation down considerably. A planet (with a substantial atmosphere) that rotates too fast could have very powerful weather systems; systems that can erode away precious topsoil, or even prevent it from ever establishing in the first place. Topsoil of course, is needed for plant growth.
Plants are needed for animals to survive (provide food and oxygen), and together along with rock are needed for a stable mix of critical atmospheric gases. Without a topsoil, the chance for advanced terrestrial civilizations to evolve is impossible. In other words, all our tech is truly worth the dirt beneath our feet.
To be fair, this topsoil business says nothing to the possibility that there exists an advanced aquatic species out there. But then again, without land there will be no fire, and without fire, there is no way to forge a path toward technology. (Sorry Aquaman, but your gig is up you land lover! arrrr!) Of course fire requires oxygen, but not too much or flames can become uncontrollable, not to mention the air would become toxic; but not too little or flames will never ignite, and the air would become asphyxiating for us oxygen breathers. No fire, no tech. It really is that simple.
Now many will cite the fact that we benefit from having Jupiter in our solar system. For years many have called it the great "vacuum cleaner" of the solar system; protecting Earth from comet and asteroid impacts by diverting them into itself under the effects of its immense gravity. This may or may not be the case. I'm sure creatures that were enjoying their day some 66 million years ago would have to disagree with the Jupiter vacuum cleaner hypothesis. Some scientists believe that same immense gravity could just as likely eject comets and asteroids from the Oort cloud and asteroid belt respectively, sending their dislodged chunks of death hurtling towards Earth (Horner et al., 2008). Given the ongoing debate, the great Jupiter vacuum cleaner hypothesis lacks enough evidence to deserve more than a mention here, so mention we have.
For an advanced species to evolve, it helps to have a stable host star like our Sun around which their planet can revolve. Not all stars are as stable as our Sun (currently is). Some stars' brightness fluctuates so much that they could send planets into a life-obliterating see-saw of deep freezes and hellish epochs ad nauseum. Tabby's star could be one such stellar nightmare.
Some stars may be stable but not bright enough, while others may be stable but too bright. Another factor to consider is stellar life; some stars may not exist long enough for life to have time to evolve (ie. hypergiants). Quiescent stellar circumstances aside, we must also consider planetary circumstances that have—or at least seem to have—had some significant level of pertinence with regard to the existence of life in all its forms.
Planets will need enough land (with topsoils) to support life (and fire) as well. But to get life of course requires abiogenesis; life arising from non-life. Though we're not sure what the exact set of conditions were when life first occurred here on Earth, we know they aligned just right to spawn life. If it can happen here, what's to say it cannot happen elsewhere in this unfathomably-vast universe?
Whatever life form spawns from beneath the protective umbra of favorable conditions then must go on to survive long enough in order to evolve into something(s) more complex. On Earth, it took a long time just for prokaryotes (single-cell organisms) to evolve, and longer still for eukaryotes (multi-cellular organisms) to develop. And longer still for sexual reproduction to evolve. Though this seems a bit peculiar to mention sexual reproduction as an important factor towards the evolution of a technologically-advanced species, the fact remains that it is absolutely crucial (not a good pick-up line). Without it, genes cannot be shared. This genetic sharing invariably passes on beneficial mutations that allow a species to adapt to a changing environment; to better compete with other species for food and habitat. All this within natural balance of course. Balance is something nature is quite adept at; though I can't extend that compliment to us despite our advances. But I digress.
That natural balance we mention is attained through diverse ecological webs chalk full of delicate-yet-robust checks and balances that have evolved over great time. Within these intricate webs are food chains that support hierarchical series of organisms, each dependent on the organism one link 'beneath' it as a source of food.
Higher-level organisms require higher-caloric intake (energy) to support themselves; particularly animals with large, active brains like us. Contrary to popular (and rather condescending) belief, there are no stupid humans; just ideologues. But I don't equate ideology to stupidity, I attribute it to a complex of emotion, and emotion is both intricate and highly evolved no matter what we're told; regardless of the action (or inaction) it provokes (or paralyzes in us). But again, I digress.
Large brains are an obvious requirement for cognitive thinking. Cognitive thinking is, of course, a measure of our ability to think critically, and this critical paradigm has led us to the invention of such things as tool & their uses, language (both verbal & written), agriculture, and ever-further advances in technology... to name a few.
And all of these advancements need to be achieved through the structured framework of societal rules and laws. Themselves highly sophisticated, if not inscrutably so.
I have to admit, I've done none of these factors any service by skimming over them so superficially, but I hope mentioning them stirs deeper thought with those kind enough to read my blogs into what should be considered when imagining the rise of other advanced civilizations.
Of course, all of this is meaningless if an advanced civilization kills itself either by war or self-induced global environmental catastrophe, before it is able to make itself known, or to come to know another civilization somewhere out there. That is, if another advanced civilization exists.
Taking all that we've discussed so far together, it seems the odds of living have indeed been in our favor. Unfortunately, with so many factors to consider, it doesn't appear too promising for other potential civilizations. But there's more to consider...
Other factors that may (or may not) be critical to life include a planet having an ocean (but one that's not too salty), a planet with the right amount of tilt (in order to have seasons), a planet that isn't consistently struck by massive asteroids or comets (give life a chance), a planet with tectonic activity (but not too active), being in the "habitable zone" of its star, a planet that is (preferably) not tidally locked (like all those planets in the Trappist system), and a host of wild-card factors.
Though it's a fairly extensive list of factors, it shouldn't be seen as a list of requirements. In fact, not all scientists believe it should even be looked at as a list of guidelines even. Some of these factors can be argued to be biases we have as to what is necessary for life; biases stemming from the fact they're ipso facto factors that have given rise to us.
We should be careful not to assume the conditions listed above that seem to have greatly aided in giving rise to life on Earth, necessarily need to be replicated elsewhere in the universe for life to evolve. Some folks tend to make this false assumption, and I believe to do so is folly. But as I always say in my blogs, and I say it with an utmost humble realization; what do I know?
There are, however, some important galactic-scale factors that would likely affect the potential for life to evolve elsewhere in the universe. And this is where we can make some assumptions as to why our place in the Universe is, for all intents and purposes, relatively unique in its hospitality.
For instance, our galaxy is fairly benign. It doesn't have a blazing quasar in its core, spewing its intense ionizing guts across the galactic bands. The intensity of a core like that could make life on any planet within the galaxy, even on the outskirts, rather difficult. Imagine the Milky Way core being several hundred trillion times brighter than it is now.
Another galactic-scale factor that might have some bearing on life is a solar system's orbit around the galactic core. Our solar system doesn't have a highly-eccentric orbit, and this is probably a good thing. If we did, then over geologic time we'd pass much closer to the dense cluster of stars in the galactic core region. The higher density of stars would awash our solar system in intense ionizing radiation that Earth's magnetosphere may not be able to shield us from. Unlike a relatively quick 365-day orbit around our Sun, our solar system (or other stellar systems for that matter), can take hundreds of millions of years to complete. As such, stellar systems with highly-elliptical orbits can spend several millennia near their galactic core. That's an awful long time to be hanging out in ionizing radiation. Though Nikolai Kardashev figured we'd have the best chance of finding extraterrestrial life by peering towards the dense core region, chances of life near the core are likely quite slim. We'll get to Kardashev soon.
Consider also that we're fortunate enough not to have any 'nearby' pulsars or magnetars spinning off lethal doses of ionizing radiation in our direction. That would be quite the sterilizing experience. Additionally, our location here on the Orion Spur is not too far, nor too close to the galactic core. I suppose we could say we're living in the galactic Goldie Locks zone.
We know being too close to the core is bad due to the intense ionizing radiation there, but being too far can be bad due to the general lack of metals. Heavier elements (like metals) are created from the expelled guts of exploding stars. This is a great opportunity for me to quote Neil DeGrasse Tyson:
"...the atoms that make up the human body, are traceable to the crucibles that cooked light elements into heavy elements in their core under extreme temperatures and pressures. These stars- the high mass ones among them- went unstable in their later years- they collapsed and then exploded- scattering their enriched guts across the galaxy- guts made of carbon, nitrogen, oxygen, and all the fundamental ingredients of life itself."
The outermost regions of galaxies have substantially fewer stars, and therefore experience fewer supernovae. The fewer stellar explosions, the fewer of those crucial elements will be produced, and the fewer of them that are available in those outer regions of the galaxy. No advanced species can develop without these heavier elements in well enough abundance to support life, and by extension, technology.
So with all this, it seems life doesn't have all that great a chance. This may be true; however, let's not forget the numbers game: There are likely TRILLIONS of habitable planets out there. That's trillions of chances of getting it right, just as we have (human politics excluded).
Breaking Down a Communication Breakdown
The Milky Way is ~13.2 billion years old. Over that time it may have had Sun-like stars that have come and gone, and during their ~10-billion-year main sequence stage, they could have hosted planets that hosted advanced civilizations; civilizations that--like us--may have tried valiantly to search for other life beyond their star systems, sending out radio signals in all directions, but went extinct without ever so much as hearing a single chirp from the cosmos.
Then again, perhaps they were heard, and answered. Perhaps there was a time, right here in the Milky Way, when two or more civilizations were in communication with each other. Perhaps it was a congenial relationship between species (imagine that), or perhaps it lead to some interstellar war. Each civilization having their own unique histories, much like we've had ours. Perhaps they had ancient empires like China, or great wars like those fought between Greece and Persia. Perhaps they had great periods of enlightenment; renaissances of such romantic and scientific depth that our own pales in comparison. Perhaps. Given the age of our galaxy, all this could have happened, and all of it long before we existed.
Contrarily, it's possible none of this happened. Either way, by the time our Sun formed (~4.6 billion years ago), these other Sun-like stars would have been nearing the end of their main sequence phase of life, during which time they'd have become too hot to support the life that might have once basked under their rays, extinguishing forever worlds we'll sorrowfully never know.
Imagine worlds that evolved as ours has, with rich histories like our own, and with delicious, far-reaching space faring missions that we've only just begun to taste. We sit on the brim of an ethereal bowl of technological ambrosia, near drooling at the prospect of diving in head first. And all of it made possible by an alignment of factors seeming to defy astronomical odds, but in a universe with astronomical potential for life. It's possible that we are the first advanced civilization to rise from our nest to spread our wings to take flight into the wider galaxy. This is a sobering, yet inspirational thought.
Whether we are the first, the last, or one of a long line of advanced civilization to live in the Milky Way or in the universe at large, the fact remains; we're mere infants when it comes to exploring beyond the reaches of Earth, and we've much more to learn.
It hasn't yet been 100 years since we first realized we exist in a universe at all. Up until the last century, our Milky Way was all that existed to us. The greatest minds on Earth had no idea the universe existed, and now children are not only aware of it, but highly inquisitive as to its nature.
Other civilizations like our own may concurrently exist and may sit on that same ethereal brim prepared to take the plunge into the deep unknown. But having only recently evolved technologically to levels capable of radio communication transmission bubble has yet to traverse the great distances of our galaxy to reach us; even if they're in our galactic neighborhood.
It could take their signals hundreds, if not thousands of years to reach our otherwise lonely corner of the galaxy. Even if an advanced civilization as 'close' as what I've depicted in the image below were to have transmitted their first radio signals into space several thousand years ago, those signals (traveling at the speed of light) would still have not reached us yet; and wouldn't for another thousand years or more.
Perhaps the reason we've not detected other civilizations yet, is simply because there hasn't been enough time for their signals to reach us.
Another possibility to consider is that their signals are reaching us, we just don't have the technology or the wherewithal to realize it. If their signals have traversed the many hundreds or thousands of light years necessary to reach us, they may be so desperately diluted that we'd be hard pressed to know they're there.
Another possibility is that they're transmitting, but not towards us. Not all signals are omnidirectional. Some are directional signals, and it is possible another civilization concentrates energy into directional lasers for more efficient communication transmissions. If those signals are directed anywhere other than our direction, then they're simply not available to us.
Though, astrophysicist Gregory Benford has a caveat to this; he has said that if an alien species wants to be heard, they'll find a way to be heard. After all, look at us. We're so desperate to be heard that some zealous members of our species have already beamed twitter feeds into space. Grrrrrreat. :/
NASA thought it prudent to beam music of the Beatles out there, and though the female genitalia was censored on the Pioneer plaque, we've even sent a spacecraft that has now traversed the edges of our solar system.
The late Carl Sagan holds the plaque depicting two human beings; a man and a womanish-looking creature (?). Needless to say, Sagan was very upset about the censorship. You can even see his abashed grin trying hard to be proud of what should be a proud moment. I'm certain he smoked a J after that shot. But again, I digress.
I suppose all this is better than aliens' first impression of us being television frequencies of reality television, or daytime talk shows. I can only imagine the puzzlement they'd experience after deciphering the meaning of, "You are not the father!" I wouldn't be surprised if we've been heard, and they choose not to deal with us.
And this is the perfect segue to our next point: perhaps they exist, but don't want to talk to us. Or, it's possible they exist, but prefer to hide and for serious reasons.
Perhaps they find the effort not worth it; all effort no gain. But as many have philosophized, this scenario seems to suggest another civilization completely lacks the gift of curiosity. Sure, there may be members of their species that don't want to talk, just as we have. But generally speaking it seems only a natural step for the intelligent mind to want to hear and be heard.
Curiosity is the very soul of science, and it seems counter-intuitive for an advanced civilization that has gotten to where it might be technologically, to have gotten there by not seeking answers to questions (curiosity) via genuine inquiry.
What if this is the case? What if there is an advanced civilization out there that purposely keeps quiet?
Then we must ask, "Why would they want to do that?"
The answers to this question can get imaginatively wild, but there's nothing to say any of the possibilities are impossible... Perhaps they'd keep quiet because they've discovered they're not alone. And that discovery reveals that there exists another far-more advanced civilizations in their immediate galactic neighborhood. That's a rather chilling thought if we think about it.
As any history buff can attest, things have rarely (if ever) fared well for a society when met with a technologically-superior group. Considering this, then we can assume they might hide in order to protect themselves. This seems legitimate on the surface, but if we ponder it further, it seems to fall flat. We must consider the notion that if they have the technology to realize they're not alone, then the civilization far more advanced than them would also have the tech to know they're there... and probably long before they themselves were detected. Besides, if we can detect them, then we can detect those they hide from.
There is a flip side to this galactic coin. We must consider the possibility that a reason another civilization doesn't communicate with us, is because they don't want to interfere with our natural evolution and sociocultural growth. Well, that's kind of a slap in the face! Thanks superior beings out there looking at us from afar like visitors to a zoo.
And so it has been dubbed; the "zoo hypothesis". There may be a large number of advanced civilizations out there, all of whom are in communication with each other, watching us like we watch YouTube, refraining from interfering (commenting) with us. It's similar to Star Trek's Prime Directive:
In fact, it's similar to ourselves in a sense. Many anthropologists have stressed the need to avoid direct contact with extremely remote tribes deep in (what's left of) the tropical rainforest and on some of the Andaman Islands.
These technologically-primitive cultures can only survive by evolving at their own natural rate; a rate dictated by their own set of beliefs, customs, and availability of natural resources. It is believed any interference on our part would serve them no great benefit, and therefore contact should be avoided. Of course we humans aren't all that great at following the prime directive. The very people who have touted the need to avoid direct contact, are often the same folks that would send a research crew, or documentary film makers, to go live with an otherwise isolated culture group for a few weeks to see how they live. Those who want to be extra careful to avoid contact, may choose to fly over remote villages in aircraft in order to film them from above. That will minimize contact and subsequent influence... right? :/
As technologically-superior people, it's our duty to "protect" these last-remaining isolated cultures by essentially probing them in much the way we've feared probing from aliens. It's the Avatar-movie-syndrome; we can save you primitives and become one with your people while doing it! Um, ya. Rather ethnocentric if you ask me. But what do I know?! And, once again, I digress!
All this leads us to our next topic; the Kardashev Scale. Just how advanced can an advanced civilization can get? See? I told ya I'd get to him soon, despite all my pseudo-philosophical tangents!
A Carbon Footprint the Size of a Galaxy
The Kardashev Scale (basically) measures the level of an alien civilization's technology by considering the amount of energy it uses to transmit information through space (Karsashev, 1964). It's a 3-tier scale based on energy consumption at planetary, stellar, and galactic scales. It is defined as follows:
Type I Civilization - A civilization consuming the energy available from its own planet; similar to ourselves but a bit more advanced. We don't quite make this list (yet).
Energy consumption of a type-I civilization ≈ 4 x 1019 erg/sec
Type II Civilization - A civilization capable of harnessing the energy of its own star; ie) utilization of a Dyson swarm or sphere utilizing hordes of star-orbiting statites.
Energy consumption of a type-II civilization ≈ 4 x 1033 erg/sec
Type III Civilization - A civilization capable of harnessing the energy of its entire galaxy;
meaning every single star has a Dyson swarm or some sort of energy-harnessing system.
Energy consumption ≈ 4 x 1044 erg/sec
Though Kardashev's paper on these three types of civilizations focuses primarily on their energy consumption as it is used for communication (amount, rate, and power of transmission), we can assume that any civilization consuming energy at these levels is also using it for other technologies.
Going on this assumption, Carl Sagan made adjustments to the scale as follows:
K0 civilization - 10^6 watts (Much to the chagrin of "developed" nations, we would be a K0.7 civilization not including food energy consumption. So we don't even make Sagan's list.)
K1 civilization -10^16 watts (About what Earth gets)
K2 civilization -10^26 watts (About what the Sun puts out)
K3 civilization -10^36 watts (About what the Milky Way puts out)
One thing to consider, is that planets, stars, and galaxies vary in size, and energy. So these numbers are more like ball-park figures so to speak. There are stars out there with circumferences so immense that it would take a commercial airliner over 1,000 years to circle the star (non-stop at full power). Whereas our Milky Way contains ~200 million stars, there are some galaxies, such as Andromeda, that contain about a trillion.
For civilizations that have managed to survive beyond the cradle of their home star, it is possible for them to survive beyond the age of their home star, and have the time needed to harness the energy of their galaxy. I don't want to rain on Sagan's or Kardashev's parade, but the chances a civilization would survive millions of years without evolving into something else is likely pretty slim. Perhaps that'll be another blog.
Now technological advancement and energy consumption are not necessarily linear. It is possible, and even likely (as we ourselves have demonstrated time and time again), that energy consumption on a per unit basis decreases as efficiency increases. I'm not explaining this well! Hmmm... Simply put, they could get a lot more (ie. computing power) for less (energy) on a per unit basis. This needs an analogy we can all grasp better than I'm explaining here...
Ahh, let's consider computer technology of the 1950s. The one-ton IBM 305 RAMAC was a state-of-the-art computer that utilized energy-intensive vacuum tube technology and moving parts. It also required the space of a 135 sq. meter-sized room (due to its enormous size). If one wanted to add an additional 5 mb of external hard drive space, they'd need even more room!
The ~2,400 watt RAMAC system was capable of processing 1 kb per second, which at the time made it one of the world's fastest computing systems. Compare this with today's ultra-basic, low-end laptop that uses not more than 1/60th the power, yet has many orders of magnitude faster computing speed.
We can reasonably expect the energy consumption of an advanced K2 or K3 civilization (if they exist) is not linear to the efficiencies and capabilities of its technology. We can only imagine what their tech is capable of at stellar or even galactic energy levels. Imagine efficiency so great, that the energy requirements of the latest iPhone could be enough to power some small alien computer the size of a fingernail, but with computing speeds so extreme they'd make the Sunway TaihuLight seem like a 1980s pocket calculator by comparison.
Their energy consumption would be a function of both their technological advancement, as well as their population size. Building a million (or billion) Dyson swarms may be impossible to a civilization with a population of, say, 7.5 billion (us). But to a civilization with populations in the trillions, such expansion isn't so difficult.
K2 and K3 civ populations could be enormous. A K2 civilization could support a population of 100 quintillion (that's 1 with 20 zeroes after it). A K3 civilization could support a population of 1 nonillion (that's 1 with 30 zeroes after it). If we're ever visited by an alien from such enormously-populous civilizations, I doubt the vast majority of their species would ever know (or care) some of their kind have visited us. That's a rather chilling thought; chillier still when we consider just what sort of technology such civilizations would be capable of.
The Matrioshka Brain -
Nothing on Earth remotely compares to the hypothetical computer power of the Matrioshka Brain (MB); a multi-layered (or swarm) computer system that harnesses the energy of an entire star. Named after the nesting Russian Matryoshka dolls (one doll fits inside the other), the MB would consist of layers of shells, each specifically spaced apart from the next layer out, utilizing the energy of the star to perform calculations.
The inner most shell receives the most energy. It converts this extremely high-temperature energy into useful calculations. Few things are more useful to an advanced civilization than calculations. Waste heat from calculations computed by the inner-most sphere is subsequently absorbed in the next layer out, where further calculations can be computed. Waste heat energy from that second layer is then absorbed in the next layer, and so on in what would be the most efficient use of energy known.
The processing speed of a computer like this (around a star like our Sun) would be gargantuan; ~1049 Hz. That's a lot of cycles, and to be honest, I cannot think of any analogies to give perspective on a number that large. It truly is beyond human comprehension.
As alluded to above, the most efficient Matrioshka Brains would utilize as much of the star's energy as possible. Of course, there is no such thing as 100% efficiency--the most physics allows is 50% and even that isn't practical--but we can imagine a K2 or K3 civilization would be very detail oriented to maximize efficiency. To squeeze the most out of a stellar orange like our Sun for instance (which is actually white star), the outermost shell of the brain would need to extend beyond the outer limits of our solar system. This is because each shell has to be perfectly spaced, and this spacing is a function of Carnot's Theorem which mathematically dictates maximum efficiencies possible for heat engines (which is what the MB effectively is).
To use every bit of energy possible, a Matrioshka Brain would have to have an outermost layer whose waste heat is the same temperature as the Cosmic Microwave Background radiation (CMB) of 2.7 Kelvin. Any less, and heat from the CMB would become problematic to calculations of the outermost shell. And that outermost shell (around a star like our Sun) would be so big that other stars would need to be moved to make room. And if we think a civilization with the capability of creating something like this is incapable of moving stars out of the way, then we must think again my friends! They'd most certainly have stellar engines such as a Shkadov Thruster. Though, I'm sure their technology would have a slightly different name.
Though civilizations capable of constructing Matrioshka Brains would obviously be more advanced than us, the fact remains that they'd be using the same math we (as in not me) have come to realize. In all its computing prowess, the Matrioshka brain can be designed with utmost efficiency by simply using the Steffan-Boltzmann Law, and Carnot's Theorem.
Point here is that they'd be using the language of the universe regardless of what tech level they're at; math! Rather than sending Twitter streams, we might serve transmissions better by transmitting meaningful math (or maths as my British friends would say).
Not all Matrioshka Brains would need a shell-within-a-shell type structure. Swarms of satellites could also be used. So next we must ask, just what sort of calculations could be done with such a computing monster.
All but the most complex (ie. The Tower of Babel mathematical thought experiment) calculations could certainly be computed. But one of the most intriguing uses of a Matrioshka Brain, would be to use it for simulation that would put the Matrix to shame. We're talking simulation on a scale so immense that the entire existence of a K3 civilization could exist within the simulated reality of the computer system itself. This of course deserves a blog all its own, but it is something that has been postulated for decades, and brought into focus by philosopher, Nick Bostrum.
A civilization that has achieved the ability to upload their brains (which we might consider to be the soul) to a massive system like the Matrioshka Brain, could experience an existence (as a civilization) far longer than the universe itself. One of my favorite YouTubers (is that a term?), Isaac Arthur, has postulated that subjective time in virtual reality could be slowed independent of real time, allowing a civilization to experience eons between seconds.
When I wrote that we are merely perched on the brim of a cosmic bowl of ambrosia, we really have no idea just how flavorful that plunge could be. The possibilities are supported by the math, and as such are nearly limitless in scope. Are we the only advanced civilization in the universe? We may never know the answer to this question, but one thing we can know, is that we are coming to know the universe. Given the fact that we are made of 'star stuff', then the next logical conclusion to make is that we truly are a way of the universe coming to know itself. And that kind of knowledge truly is the nectar of the gods.
As always, thanks for reading.