Three conditions are necessary for SETI to succeed

The Parkes 64 metre radio telescope at the Par...
(Photo credit: Wikipedia)

Tom Hartsfield has a post up at Real Clear Science criticizing both the Drake equation and SETI:

If you like science fiction, you’re probably familiar with the Drake equation. This famous one-line formula solves for the number of intelligent alien civilizations within our galaxy with whom we might be able to communicate. Supporters of the search for extraterrestrial life (SETI) often refer to the expression to bolster their case.

There’s just one BIG problem with the Drake equation. It’s completely useless! In fact, I believe it may actually misrepresent the search for ET and limit our ideas about it.

Hartsfield goes on the discuss the impossibility (at least currently) of knowing the values for each of the variables.  Because of this inability to test or observe the various values, he says, the formula is non-scientific.

He then takes aim at SETI (the search for extraterrestrial intelligence):

The worst thing about the Drake equation is that it gives us a false idea of grasping the problem we are trying to solve. A mathematical equation connotes some scientific study or understanding of a subject. But this is misleading: SETI is simply NOT a scientific endeavor. It’s entirely a leap of faith, albeit a leap that uses tools devised by science. It’s like searching for paranormal activity with an electronic sound recorder.

Now, I happen to think that, due to the Fermi Paradox (if there are thousands of civilizations out there, why aren’t any of them here?), the probability of large numbers of civilizations within our galaxy is pretty small.  That doesn’t mean there aren’t civilizations in other galaxies, but they may be hundreds of millions of light years away.

That being said, I think Hartsfield is being overly harsh in his assessment.  The Drake equation has never been meant to be anything other than a stimulus for discussion.  Most people who understand this subject know that it’s essentially just structuring our ignorance.  Given its original goal, and given that people still talk about it today, I think it is fairly successful.

Is it scientific?  That depends on your definition of science, but I think the variables are things humanity may be able to measure, someday.  A scientific theory doesn’t have to be testable immediately in order to be considered science; it just needs to be testable in principle.  I don’t know too many people who would actually call the Drake equation a theory, but to what extent it’s modelling the problem might eventually be testable, at some point in the future.  I think everyone acknowledges that the Drake equation is almost certainly incomplete, in that there are probably numerous factors that influence the final number that we’re simply not aware of yet, but that applies to many things in science.

I think calling SETI unscientific is simply engaging in polemics.  SETI is definitely a long shot.  But the search is being conducted carefully and empirically.  Saying that the people who are going about it aren’t being scientific, comparing them to paranormal investigators and the like, is just making a value judgment about their enterprise while pretending to be objective.

Now, as I said, I do think SETI is a long shot.  There are certain things that have to be true for it to work.

  1. There needs to be a large number of civilizations out there.  Enough that a number of them are close enough for us to detect them.
  2. Pervasive interstellar travel needs to be impossible, or so monstrously difficult that hardly anyone bothers.  Otherwise they would have been here long ago.  Even if only 1% of light speed is achievable, that’s still fast enough for a fleet of self replicating probes to colonize the galaxy in 100 million years.   (No, there’s no evidence that they’ve been here, despite what the Ancient Aliens people say.)
  3. They need to communicate in a manner that is detectable with our current technology.  If there are civilizations out there, they may be advanced in ways we can’t fathom, and us attempting to listen in on them may be far more fruitless than a primitive hunter-gatherer tribe attempting to listen in on global communications, by watching for smoke signals.

It seems to me that these three constraints make success for SETI unlikely, but not impossible.  And nothing about how unlikely it is to be successful necessarily makes it unscientific.

Personally, given 2 above, one strategy to find extraterrestrial intelligence may be to search for probes in the solar system.  It may be that there are several already here, laying low.  Of course, if they are here and dormant, you have to wonder what they’re waiting for, how far advanced the civilization on the third planet is going to have to be before they initiate contact.  And given the vastness of the solar system, if they don’t want to be detected, the chance of us being able to do so seems remote.

Eavesdropping on E.T. and the possibility of interstellar travel

Gabriel Popkin as an article at Inside Science about a study that looks at the possibility of intercepting communications between other alien civilizations.  The idea is that communicating across interstellar distances is best done with lasers.

So far, the optical search for extraterrestrial intelligence has focused mainly on the hope of receiving—and recognizing—an intentional, laser-encoded message. Researchers use dedicated telescopes or mine astronomical data collected for other purposes, like the Sloan Digital Sky Survey, to search for light pulses that could not be produced by any known object like a star. So far, no one has reported a light pattern that suggests an extraterrestrial intelligence.

But rather than look for light beamed directly at us, astronomers could also try to intercept signals sent between two distant civilizations. If advanced beings have existed for millions of years, they may well have found each other and started talking. Eventually many light beams would penetrate the intergalactic darkness, creating a criss-crossing network of communication beacons. As our solar system revolves around the galactic center, could we meander into the path of one of these beams?

While an interesting idea, the study largely concluded that this is unlikely to happen.

Unsurprisingly, he found that the chance of intercepting another civilization’s messages increased as more civilizations joined the communications network. He also found that the interception probability increased dramatically as the angle through which the beams spread out increased.

But the probability of accidentally wandering through a beam remained small as long as the beams were narrow, or collimated, like a typical laser. The beams would have to spread out about 1,000 times more widely than a standard laser pointer—in other words, more like a flashlight beam—before we have a decent chance of intercepting them, Forgan says. Sending out such a wide beam would require far more energy than emitting a tightly collimated one.

This isn’t too surprising.  Interstellar space is vast, and solar systems are (relatively) tiny.  As the article discusses, the aliens would have to go expensively out of their way to increase the odds of being detected by a third party.

One thing I find interesting about these studies, is that they have an implicit assumption: that interstellar travel or exploration is impossible, even robotically.  Because if it is possible and there are indeed hundreds of civilizations in the galaxy, then there would likely already be a communication relay in every solar system, and a vast interstellar communication web network.  If so, then our system would almost certainly have multiple beams interacting with other nearby stars.

If the aliens don’t want to be detected, it is possible that they could keep their relay stations in the Oort cloud, the region of comets and other icy bodies extending for a couple of light years out from the sun.  Of course, avoiding detection would have to be a major priority for them to keep their facilities so far away from the free solar energy of the sun.  But they could have decided to do so as soon as they noticed a tool using species developing on the third planet.  And if staying  hidden is a priority, we’re unlikely to find them for a while.

But, is the assumption that interstellar travel is impossible a valid one?  Or are SETI and other astronomers being overly pessimistic?  Most people are aware of the speed of light limitation, that nothing can travel faster than light.  But lamenting that issue is actually a bit of sour grapes, since we don’t even have the foreseeable technology to get to a significant percentage of the speed of light.  Just getting to 10% of c (the speed of light) will require astounding amounts of energy.

But it’s hard to imagine that in the centuries and millennia ahead, that we won’t be able to cobble together some method of getting to at least 1% of c.  There have been designs around for decades, such as the Orion Project, which would use nuclear explosions to propel a craft up to a high speed.  And there are many more speculative designs out there that could conceivably improve on that.

The problem is that Orion would still take centuries to reach the nearest star.  It’s easy enough for science fiction writers to wave their hands and imagine robotic probe machinery working that long, but engineering it is a different matter.  Still, Voyager 1 is four decades out and is expected to work at least another decade, albeit in a very low power mode.  Building a probe that could work for centuries would be difficult, but it remains an engineering challenge, not a fundamental limitation of physics.

And I think that’s why I remain optimistic that interstellar exploration will ultimately be possible, at least with robots.  Because the issues to be overcome are engineering ones, not fundamental scientific ones.  It’s hard to say whether those engineering challenges will be overcome in a century, a millennia, or farther out, but insisting that they never will seems unnecessarily pessimistic.

But as soon as we reach that conclusion, we’re back to wondering where everyone is (the Fermi Paradox).  Either they (or more likely their robotic representatives) are already here in the solar system, and hiding, as described above or in some other way, or they’re simply not there.  Or perhaps more accurately, the nearest neighboring civilization is millions of light years away in another galaxy, far enough away that they haven’t had time to reach us yet, if they ever will.

How should we communicate with aliens? Should we communicate?

The array of telescopes atop Mauna Kea (Hawaii)
The array of telescopes atop Mauna Kea (Hawaii) (Photo credit: Wikipedia)

Seth Shostak has a post up at HuffPost asking what we should say if we ever find ourselves in conversation with aliens.  Apparently this was the topic of a recent conference at the SETI institute.

Before commenting on Shostak’s main thesis, I think he makes an assertion that deserves scrutiny.

A decade of research by astronomers now suggests that a trillion planets dot the Milky Way. It takes a real Debbie Downer to believe that they’re all as dead as the Equal Rights Amendment.  Unless Earth is special beyond reason, you can confidently assume there are plenty of societies out there.

I’ve got no problem with this statement, until the last sentence, where Shostak takes a logical leap.  (Albeit an understandable one being he’s a member of SETI.)  Certainly, unless Earth is “special beyond reason”, we can expect plenty of worlds with life out there.  Given the history of life on Earth, I think we can expect most extraterrestrial life to be simple microscopic organisms.  Complex life (plants and animals) will likely only be on a minority of worlds.

And given that the Earth was 99.995% of its current age before an intelligent species arose, and also given the Fermi Paradox (if there are plenty of civilizations out there, where is everyone?), I think we should expect intelligent life to be exceedingly rare.  Rare enough that our closest intelligent neighbor may be millions of light years away in another galaxy.

Of course, it’s always possible that interstellar travel is impossible and that the only way civilizations could ever interact with each other is by signaling across the void.  And that gets to Shostak’s main topic.

A leitmotiv of the conference — one thing that just about everyone felt they could agree on — was to beware of anthropocentrism. Don’t assume that the way we think or describe things will be the same for the extraterrestrials. Context and local knowledge are the frameworks of our daily lives, and it’s easy to forget that these are peculiar to us, both in place and in time. The aliens will not get our jokes, our literature, or our reality TV. Their minds, presumably vast and deep, could be as different from ours as those of bats and beetles.

The problem isn’t even anthropocentrism, it’s terracentrism (don’t know if that’s a word, but I’m making it one).  We might have some hope of rising above anthropocentrism by comparing ourselves to non-human animals, but aliens that evolved in a radically different environment may think so differently that even communications like pictures or mathematics may simply be assuming too much.

The fact is, we probably have little hope of figuring out, a priori, how we need to communicate with extraterrestrials.  With that in mind, I agree with Shostak that, if we choose to communicate (more on that in a bit), we should do so liberally.

It’s a tough problem, and my own contribution was to opine that — rather than wrestle endlessly with what we should say — we send it all. Or at least send a lot. I suggested that we transmit the contents of the Internet, or some large subset thereof, rather than offering up more “greeting cards” similar to those that have been bolted onto some of our spacecraft. Sure, there’s a lot of silly stuff on the web — it’s not curated, to use the language of museums. But it’s wide-ranging, covers a lot of human activity, and is highly redundant. For example, the concept of “automobile” is present in descriptions, photos, and videos. That redundancy will help them — assuming they have the processing power — to figure out a lot of what we’ve sent.

In other words, give them enough so that they have a chance of piecing together our concepts.  If you think about it, if we were receiving communication from an extraterrestrial civilization, that’s probably how we would prefer to receive it.  Inundate us, and let us figure it out, particularly since interactive communication is probably going to be impossible, with replies likely to take centuries, if not millennia.

But this raises the question of whether we really should communicate.  Any other civilization that we’re likely to contact would almost certainly be far more advanced than ours, and by “far more”, think millions of years more advanced.  The probability of us connecting with another civilization that just happened to emerge within a few thousand years like we did, is infinitesimal.

Even if they’re 500 light years away, and the soonest they could conceivably affect us would be over a thousand years from now, that’s likely not nearly enough time for us to catch up technologically and be on anything like the same level as they would be.  Communicating with them may simply be the mouse summoning the cat.

Of course, it’s hard to see why an advanced civilization would bother conquering us.  Any desirable natural resources we might have would be much easier to obtain in the Kuiper belt, or on other planets without the bothersome resistance of the inhabitants.  And our biologies aren’t likely to be compatible enough for them to eat us.  (In any case, it would be easier to synthesize the food rather than travel interstellar distances to obtain it.)

But we should consider that it likely wouldn’t even amount to conquest for them.  Their attitude toward us might be the same as that of a scientist studying mice, and experimenting on them.

I suspect that it we ever did receive a signal, we’d get a lot of clues from what was in it.  If there was extensive information about themselves, including information that helped us solve many technological problems, then we might be able to assume they were benign.  On the other hand, if all we received was the interstellar equivalent of a dial tone, we would probably want to carefully consider our next move.

If evolution started over, how similar would its results be?

Zach Zorich has an interesting piece at Nautilus asking if the world began again, would life as we know it exist?

In less than five milliseconds, a Hydromantes salamander can launch its tongue—including the muscles, cartilage, and part of its skeleton—out of its mouth to snag a hapless insect mid-flight. Among amphibians, it is the quick draw champ. Frogs and chameleons are comparative slowpokes when it comes to their ballistic anatomies. “I’ve spent maybe 50 years studying the evolution of tongues in salamanders,” says David Wake, an evolutionary biologist at the University of California, Berkeley, “this is a particularly interesting case because salamanders, who don’t do anything fast, have the fastest vertebrate movement I’m aware of.” Within their lineage, evolution found a better way to accomplish tongue-hunting. Their seemingly unique adaptation appears to have evolved independently in three other unrelated salamander species. It is a case of convergent evolution—where different species separately developed similar biological adaptations when faced with the same environmental pressures. Salamanders are Wake’s go-to example when asked a decades-old question in evolutionary biology: If you could replay the “tape of life” would evolution repeat itself? In the salamanders, it appears it has: In other organisms, it may not have.

Zorich’s piece describes some fascinating experiments testing this question, and is well worth reading in full.

My own view is that this is really two separate questions.  The first is how likely is the rate of evolutionary “progress”, or increases in complexity and capabilities?  The second is, if those increases in complexity and capability did happen again at a similar rate, how similar would the results be to the ones we observe today?

On the first question, I can’t see that it is at all guaranteed.  There’s nothing to make us believe that the development of complex life was inevitable.  It took billions of years on Earth.  Viewed on geological timescales, complex life is a recent innovation.  The Earth was 87% of its current age before the Cambrian Explosion took place.  Complex life does predate the Cambrian, but 75-80% of the Earth’s age had elapsed before it developed.

Earth probably only has another 500 million to 1 billion years before the sun’s growing heat makes life impossible.  In other words, it took life most of the time it’s going to have (4 billion years out of a likely 5 billion year window) to evolve complex life.  If we started over, it’s very possible that life would never get out of the microscopic phase in time.  Of course, it’s also possible complex life might have developed earlier; we just don’t know.

But if complex life did develop, and if the environment were the same, how similar would the results be to today’s life?  I’m tempted to think that we’d see very similar ecological niches to the ones we have now.  The many examples of convergent evolution would seem to bear something like this out.

However, we have to remember that a large part of the environment is caused by life itself.  The oxygen in the atmosphere first came about from early life, and the continued oxygen levels are maintained by life that outputs it as a waste product.  Many of the optimal shapes for land animals are related to trees, grasslands, and similar life that they have to navigate through and around.  Much of life lives in an environment generated by life itself, in the biosphere.  If life started over, that biosphere would almost certainly be radically different.

Still, broadly speaking, I would expect some functional similarities.  For example, you’d still have life living in the water, and the same fish shapes that are conducive to moving through the water would be conducive again if life started over.  Many of the same shapes that are optimal for moving over land surfaces would be optimal again.  It would still be productive for species to eat other species in a food chain.  It would still be optimal for sense organs to be in the front and highest part of an animal’s body.

But within those broad functional niches, there would almost certainly be differences that we would find radical.  For example, I see no guarantee that sexual reproduction would exist, or if it did that it would resemble anything we’re familiar with.  While creatures that can regulate their own body temperature might exist, something like mammalian glands might never develop.

Of course, all of this is speculation on my or anyone else’s part.  As Zorich describes in his article, evolutionary experts are divided about it.  Unless and until we have access to life that evolved independently in its own environment, in other words, until we have access to an extraterrestrial biosphere, we won’t really know.

One point that I do think we can assess with high probability: if life started over, humans wouldn’t exist.  Turn back the clock by 1% of Earth’s age (45 million years), and nothing resembling humans had evolved yet.  Humanity’s existence is a very recent phenomenon, and civilization is a blink of the eye in geological time.

Would some intelligence capable of a technological civilization eventually develop?  Given the time constraints on complex life I mentioned above, and the amount of time it took a technology using intelligence to develop on Earth, it’s hard to say that it’s likely.

Many people point to the other intelligent species out there, such as crows, dolphins, elephants, octopuses, and so on.  With all those other intelligent species, wouldn’t it be likely that one or more of them would eventually evolve into a technology using species?  And if so many intelligent species developed this time around, wouldn’t that make it likely that a technology using species would develop in a rewound world?

The problem is that developing a technological civilization requires more than just brain power, it requires a body plan with enough dexterity to manipulate the environment.  So far, primates are one of the few species groups, perhaps the only one, that has managed to develop this type of body plan, and only great apes (including humans) managed to pair this body plan with high intelligence, and only very recently in evolutionary time.

I think the probability of life producing a technological civilization is very low.  Given the existence of the Fermi Paradox, it seems reasonable to conclude that it is profoundly rare event.

So, to summarize, if life started over, I think there’s a good chance complex life wouldn’t develop, but if it did, we’d see a lot of creatures that, from a distance, looked similar to the creatures alive today, but that would likely still be different in many ways hard to imagine.  I think the probability of human level intelligence developing would be profoundly low.

The Fermi Paradox – Wait But Why

The “Wait But Why” blog takes an in depth look at something some of us were discussing on another thread: the Fermi Paradox.

Everyone feels something when they’re in a really good starry place on a really good starry night and they look up and see this:

Some people stick with the traditional, feeling struck by the epic beauty or blown away by the insane scale of the universe. Personally, I go for the old “existential meltdown followed by acting weird for the next half hour.”

But everyone feels something.Physicist Enrico Fermi felt something too—”Where is everybody?”

full article at The Fermi Paradox – Wait But Why.

I’ve written myself about the Fermi Paradox, and my belief that the simplest explanation is that intelligent life is very rare.  But I’ll fully admit that this is an area where there’s still lots of rooms for possibilities.  That said, I think we can be pretty confident from the paradox that the Star Trek version of reality, with scores of alien civilizations within a few dozen light years of Earth flying around faster than light, doesn’t exist.

xkcd: Fish

xkcd on the Fermi Paradox.  Click through for the full sized version.

xkcd: Fish.

We might find extraterrestrial life soon, but intelligent life?

Alien
Alien (Photo credit: Wikipedia)

Forbes has an article up noting that many scientists, including Seth Shostak, are now saying that we could find intelligent extraterrestrial life in the next twenty years.  I definitely think we might find extraterrestrial life in that time frame, but I’m pretty skeptical that it will be intelligent.

I’ve written about this before, but the summary is that the universe is far older than our planet.  There has been plenty of time for intelligent aliens to have evolved.  But if they had evolved, they should have been here long ago.  Indeed, we should have been colonized many times over.  But there’s no evidence of that having happened.  This is known as the Fermi Paradox.  If all the statistics point to pervasive intelligent life, then where are they?

There have been lots of proposed answers to the Fermi Parafox, such as the rare earth hypothesis (discovering any other world with life would falsify this one), berserkers, interstellar travel is impossible or hopelessly impractical, and many others.  Personally, I think the most likely scenario is simply that intelligent life is very rare, and that the nearest extraterrestrial civilization may be millions light years away.  Too far away for any of them to have reached us yet.

Of course, there are more disturbing alternatives.  It might be in the nature of intelligent life to destroy itself, we are living on borrowed time, and the possibility of us encountering another intelligent species in our mutually brief existences is remote.  Or intelligent life might be pervasive, and we’re staring right at it, but like a troupe of monkeys unable to recognize the significance of buildings and machinery, we might be mistaking their technology for natural phenomena.

If intelligent life is pervasive, and some form of interstellar travel is at all possible, then it’s probably reasonable to assume they have probes in the solar system right now.  Our first evidence of them may be when we stumble on one of their probes on Mars or in the asteroid belt.  Although with a rich biosphere on the third planet, you’d think they’d have parked themselves somewhere close to observe, but who knows?  (No, there’s no good evidence for UFOs.)

So, it won’t surprise me much if, in the next few decades, we find evidence of life on an exoplanet, or possibly even in our solar system.  But I’ll be pretty surprised if it attempts to start a conversation with us.

The faster interstellar travel is, the further away intelligent aliens are

Ethan Siegel has an excellent post up exploring the possibility of extraterrestrial civilizations.

With hundreds of billions of stars (visible, above, in infrared wavelengths) in our galaxy alone, and literally trillions of planets around them, we have many, many chances for life to have evolved similarly to how it did here on Earth. With at least 200 billion galaxies in the Universe, it seems unfathomable to us that we would be alone as the only self-aware, intelligent, sentient lifeforms in the Universe.

And yet, the titular question of this article — where is everybody — is one of the most famous puzzles in modern science: Fermi’s Paradox. If the Universe is so conducive to life, and if there are so many opportunities for it within our galaxy alone, why isn’t there any evidence of extraterrestrial life?

via Throwback Thursday: Where is Everybody? — Starts With A Bang! — Medium.

Ethan’s piece is excellent and I highly recommend reading it.  But he only obliquely refers to a factor that I consider important in this question, which I’ve written about before: the degree to which interstellar travel is possible.

It seems to me that everything Siegel lays out is correct, if interstellar travel is effectively impossible.  I say “effectively” because we know it’s possible in the sense of Voyager leaving the solar system and passing by other stars tens of thousands of years from now.  But effective means getting there in some sort of usable time frame, and with technology that is able to function when it arrives.

For that to be conceivable, it seems like the probe needs to get there within a few centuries at most, which implies achieving speeds of at least 1% of the speed of light.  Is that possible?  I don’t think anyone can say for sure, but it seems very conceivable to me that it is using foreseeable technologies.

If it is possible, then it would only require self replicating probes around 100 million years to colonize the entire galaxy.  The galaxy has been around for 13 billion years.  We’ve haven’t been contacted by any of these probes, which implies that it is unlikely that there are any other advanced civilizations in our galaxy, putting the closest civilization possibly millions of light years away.

I’m admittedly ignoring the possibility of “prime directives” and such, mainly because it’s hard to imagine such a directive holding across multiple civilizations and billions of years.

If faster travel is possible, then the distance to the next civilization is further away.  If some form of faster than light travel is possible, the next civilization may be outside of the visible universe.  For a common science fiction trope to be reality, that of alien empires that haven’t noticed us yet, they’d most likely have to operate across distances of billions of light years.

How far away is the closest extraterrestrial civilization?

Screen shot of SETI@Home (Enhanced 5.27) BOINC...
SETI@Home (Photo credit: Wikipedia)

First, let me be clear on what I’m talking about: intelligent aliens with an advanced civilization.  This is a different question than extraterrestrial life in general.  For life in general, particularly simple life, I’d be surprised if we’d have to look more than a hundred light years from Earth.  (We may know the answer to this in a few years afer the James Web Space Telescope comes online.)

But any question about the existence of intelligent aliens has to grapple with the Fermi Paradox: if extraterrestrial civilizations exist, then where are they?  Why aren’t they here?  Or why don’t we have evidence of them visiting us in the past?  (And we don’t have any evidence, despite what the Ancient Aliens and Chariots of the Gods people claim.)

SETI, the search for extraterrestrial intelligence, continues to search, and they may well eventually find something, but it seems likely that the nearest stars have been ruled out.  Of course, this is an area where we don’t know everything we don’t know, and the possibility remains that aliens are shouting at us in some manner that we haven’t yet thought of.

But the idea that the nearest civilization is close, essentially comes with the assumption that interstellar travel is impossible.  If it is possible, then again, why would relatively close civilizations not be here yet?  Given how incredibly young our civilization is (in geologic and astronomical time), any other technological civilizations would almost certainly be far more advanced than us.

Maybe interstellar travel is impossible?  It’s conceivable that the hurdles involved would be so insurmountable that no civilization has yet succeeded in making it happen.  Or it might simply be so monstrously expensive in terms of resources that no civilization bothers.  (Imagine if the mass of an entire planet is needed to attain relativistic velocities.)

But this idea deserves some scrutiny.  It’s hard to imagine that technology that would allow travel at least at 1% or so of the speed of light couldn’t be designed.  Nuclear pulse propulsion, essentially ejecting nuclear bombs behind a spacecraft with a pusher plate to get up to a few percent of light speed, seems doable with foreseeable technology.  And that’s all that would be required for self replicating probes to explore and colonize the entire galaxy within 100 million years or so.  (I know that’s a long time, but it’s quite a short time in relation to the age of the Earth or the universe.)

Perhaps that has happened, and there are currently probes of that type in the solar system, waiting for us to achieve a certain level of development before they contact us.  Perhaps, but you would think electromagnetic communication would have been a substantial marker.

So, if interstellar travel is possible, then what does that say about how far the closest civilization is?  I think it says that they’re not in this galaxy.  It’s possible that they may not even be in the local group of galaxies.  In other words, they may be tens of millions of light years away.

That is why, in an earlier post, I contemplated that extraterrestrial civilization may be exceedingly rare.

This assessment assumes that interstellar travel would be limited to the speed of light.  What if any form of FTL (faster than light) travel is possible?  It depends on just how fast, but I think it increases the distance by orders of magnitude.  The faster travel ability would simply make it likely that they’re even farther away, perhaps outside of the visible universe.

Actually this would make a common science fiction scenario, that there are lots of civilizations out in the universe, but that none of them have noticed us yet, much more plausible.  If civilizations are separated by tens of billions of light years, then the chance of any two civilizations running into each other, no matter how fast they can travel, becomes virtually zero.

At least until both civilizations have started expanding and colonizing on a massive scale.  The sheer number of stars, hundreds of billions of stars in hundreds of billions of galaxies, make it very plausible, even if the observable universe could be travelled quickly.

Of course, we have scant reason scientifically to think we can travel faster than light.  It might be possible, but it will probably take a new physics.

I also could be dead wrong about the feasibility of interstellar travel, even at sub-light speeds.  And SETI might simply not be listening yet in the correct manner.  If so, then the next civilization might very well be close (less than 100 light years), and we just need to figure out how to communicate with them.

Beasts or gods; why a War Of The Worlds is very unlikely

Image credit: Alvim Corrêa via Wikipedia
Image credit: Alvim Corrêa via Wikipedia

One of the scenarios that is often played out in science fiction is what would happen if we encountered an alien civilization.  Often, we are portrayed as defending Earth from an alien invasion or fighting battles with the aliens in a war.  Another scenario, commonly found in more culturally introspective fiction, focuses on what our responsibility would be if we encountered an alien society less advanced than ours.

These stories are a lot of fun, and they often give an opportunity for commentary on colonialism and other cultural issues in our society.  But the chances of either of these, or similar, scenarios actually happening is infinitesimal.  To understand why, let’s do a thought experiment.  Imagine three worlds, which we’ll call Planet A, Planet B, and Planet C.

Planet A is Earth.  It is about 4.5 billions years old.  Life began around 4 billion years ago.  Anatomically modern humans evolved around 200,000 years ago.  Planet A currently has a technological civilization which developed in the last few centuries.

Planet B is exactly the same as A, with the exact same history, except it is 1% younger (about 45 million years).  The dinosaurs have gone extinct on Planet B, primates have appeared, and there are a few other species with promising trends toward intelligence, but there is nothing on B that the inhabitants of Planet A would even remotely characterize as a civilization.

If the inhabitants of A decided to colonize B, the inhabitants of B would not even recognize the significance of A’s arrival.  To B inhabitants, A inhabitants would simply appear as a new type of animal.  Their equipment would also appear as new animals.  Their buildings and other structures would simply look like new kinds of rock or other parts of the landscape.  Not only would B not have any defenses against A, they wouldn’t even recognize that they were being invaded.

Now, imagine Planet C, which is identical to Planet A, except it is 1% older, or 45 million years further along the evolutionary path.  If C inhabitants came to A, would the inhabitants of A even necessarily recognize what they were seeing?  And if they did, what are the chances that they’d have any effective defenses against an invasion?

Of course in reality, even in the extremely unlikely event that another world was Earth’s identical age, the randomness of things like a different sized star, a different distance from that star, different chemistry, different mutations, different timing of asteroid strikes, volcanic eruptions, and an infinity of other factors would guarantee a unique timeline and development for that world.

If we do encounter extraterrestrials, from our perspective, they will either be, at best, animals we wouldn’t regard as intelligent, or gods.  The probability that we would meet a civilization anywhere near us in development, close enough for there to be any kind of real contest between the two of us, is virtually zero.

When thinking about contact with a more advanced civilization, we should bear in mind the way that we’ve historically treated creatures far less intelligent than us.  While we’re beginning to think that maybe we should treat chimpanzees better, most of us still have no problem with treating most of the rest of the animal kingdom as a food source, as beasts of burden (slaves), pets, experimental subjects, or nuisances to be exterminated.

Belief that a more intelligent species must be benevolent is a nice idea, but I can’t see any reason to suspect it must be true.  Any intelligent species would have had to evolve in a competitive environment, just like we did.  And just like us, their instincts toward less developed life forms would likely be to regard them as slaves, experimental subjects, nuisances, or at best, pets.  (There’s little chance they’d be interested in eating us however, since the probability of their chemistry being compatible with ours is likely nil.)

This is one of the reasons that initiatives like Active SETI have always struck me as profoundly misguided.  Shouting out into the wilderness may have consequences for our posterity that we can’t imagine.

The good news is that the Fermi’s paradox indicates that, while there is a good chance of life elsewhere in the galaxy, there probably aren’t a vast number of civilizations out there.