Gwynne Dyer: The risks of extraterrestrial contact

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      I really liked the furious debate that broke out recently among astronomers about whether we should send out signals to the universe saying “we’re here.”

      It implicitly assumes that somehow, if your science is really advanced, then interstellar travel is possible. 

      I like it because I hate the idea that the human race will never be able to go beyond this little planetary system “far out in the uncharted backwaters of the unfashionable end of the western spiral arm of the Galaxy,” as Douglas Adams put it in his Hitch-Hiker’s Guide to the Galaxy.

      We need somebody to do to Einstein’s physics what Einstein did to Newton’s. But while we’re waiting for that, it’s good to know that some quite grown-up scientists (astronomers, not physicists, admittedly, but I’ll take whatever I can get) think it’s worth having a debate about whether we should take the risk of letting all the aliens know we are here. 

      I missed the debate when it took place at the American Association for the Advancement of Science’s annual conference in San Jose last month because I was on Mars at the time. (Well, somewhere that felt quite like Mars, anyway.) But here’s a couple of quotes to give the flavour of it.

      “Any society that could come here and ruin our whole day by incinerating the planet already knows we are here,” said Dr. Seth Shostak, Senior Astronomer and Director at the Center for SETI (Search for Extra-Terrestrial Intelligence) Institute in California. 

      Not so fast, said space scientist and science-fiction writer David Brin. “The arrogance of shouting into the cosmos without any proper risk assessment defies belief. It is a course that would put our grandchildren at risk,” he said. If we send them messages, they may come here and enslave us. Or just eat us.

      Now, the traditional way to shut this debate down is to point out that we’ve already been sending out radio and television signals for 100 years. Therefore, any intergalactic pirates within 100 light-years of here already know where we are. But it turns out that this isn’t actually true: our radio and television signals begin to fade into the background radio static beyond about one light-year away.

      Since the nearest star is more than four light-years away, there’s not much chance that the Klingons or Vogons or whoever you’re worried about knows we’re here yet. (And there goes the plot of Galaxy Quest.)

      On the other hand, powerful radar signals of the kind that we have been using to map the surface of other planets and moons in our own system travel a very long way, and we’ve already been sending them out for over 20 years. They don’t carry much information—they just say “somebody here can generate microwave radiation”—but just that might be enough to attract unwelcome attention.

      This new debate is actually about “active SETI”.  We have been doing “passive SETI”—listening for messages from civilizations around other star—for more than 40 years already, using large radio telescopes that can pick up very faint signals. But there are quite strict rules about who should reply if they do get a message.

      The First Protocol, drafted by the International Academy of Astronautics SETI Panel in 1989, says that “no transmission in response to a signal or other evidence of extraterrestrial intelligence should be sent until appropriate international consultations have taken place.”

      But the advocates of “active SETI” want to scrap that and send out an “all call” to the universe. 

      One of the reasons the debate has got more heated is that we now know planets are as common as dirt. It’s only 20 years since the first confirmed discovery of an “exoplanet”, but now we know of 1,906 of them, mostly orbiting relatively nearby stars and a very small proportion showing Earth-like characteristics. (But the actual number of Earth-like planets may be much higher, since it’s a lot easier to find gas-giants like Jupiter or Saturn.)

      There are probably hundreds of thousands of planets in our vicinity (there are 260,000 stars within  250 light-years). If even a mere few thousand of them are Earthlike, then it is imaginable that somebody might come calling in response to the messages we send—if, and only if, it is possible to travel at near- or trans-light speeds. 

      Nobody knows how light-speed travel could be done, and our current understanding of physics says that it can’t be done. But this would be a very silly debate if scientists were really all convinced that there is no possibility of getting around the current speed limit. 

      They will never say that it might be possible, because they cannot suggest how it might be done and the risk to their reputations would therefore be extreme. But they are quite happy to engage in a debate that would be totally irrelevant if they didn’t think there is a chance that we—or some other civilization in our galactic vicinity—will eventually figure out how to do it. And that cheers me up considerably.




      Mar 30, 2015 at 12:18pm

      You don't need to "get around" the current speed limit [light speed] to send interstellar probes/ships. You just need to have a little more patience than our current mayfly mentality can grasp.

      In the 1960's Freemon Dyson, among others, came up with "project orion". This is basically a crude nuclear-bomb powered spacecraft that accelerate 100,000 tons to 3% of the speed of light, and then slow it down at the other end. Or if you have another way to brake at the destination, such as a magnetic sail/parachute, you could get there at 10% of the speed of light. And that's pretty much with 1960's technology, for 10% of the USA's gdp per launch. We can already build interstellar probes. We just aren't ruthless enough, or committed enough, to do it.

      And we have only had technology for a *very* small window of time. If you only assume that a society lasts a few thousand years, and their probes should be able to be fairly small, then it's easy to imagine they've send out tens of thousands - or millions - of probes to their stellar neighbourhood.

      Within a decade or two, we expect to put up space telescopes that can see which nearby stars have planets with biospheres. There are already designs sketched up that could do that for the nearest several hundred thousand stars.

      So the scope of what's possible, and our level of ignorance, is very broad, without assuming fantasy-physics.

      It's perfectly possible that there are dead or sleeping probes (aka Bracewell Probes) already in our solar system, or a nearby system. It's also possible that a probe (or bomb) could be on its way already, to arrive in a few decades. Or that the lack of said probes so far means our neighbourhood is empty. Einstein is not a limit on these scenarios, only on how quickly they might occur.

      Nice assumption..

      Mar 30, 2015 at 5:12pm

      That advanced civilizations are stuck to the speed of light.

      How does he know?

      Ford Prefect

      Mar 30, 2015 at 6:44pm

      Many scientists expect habitable planets to be within a certain range of their parent star. Not too hot, not too cold, but just right.

      It may be too that not only does a planet need to be the right distance, but also the right age. Not too young, not too old. We can't communicate with amoebae for obvious reasons, but a very advanced life form may have already killed itself off.

      I'm not sure I trust humans not to mess things up if we escape our solar system. Heck, I worry what'll happen to the Blue planet after we colonize the Red planet.

      But hopefully smarter people than that will be the colonizers.

      David English

      Mar 30, 2015 at 6:49pm

      There's nothing wrong with going slow, you just have to live longer.

      Our descendants, flesh or machine (or both), will live a lot longer than we do. Quite possibly, they will live for as long as they want, even forever. The first Voyager probe will take roughly 20,000 years to travel one light year. It's going pretty slow. It would take 40,000 years to get to the next star. What's 40,000 years to something that lives forever?

      Let's say we send out another probe, this one sentient, and it's going 10x the speed of that first Voyager. It gets to the next star in 4,000 years. That's not bad. So, let's say that probe has enough smarts and tools to gather material and then replicate itself and a launch vehicle... say it takes a few thousand years to get that done. Then, it launches 2 more of itself to other stars. Now we've got exponential growth.

      Let's say, including the replication time, the average time between stars in our galaxy is 20,000 years. If you do the math, we'll have probes at every star system in this galaxy in about a million years. That's not bad either, especially when we're talking about going a mere 10x faster than a probe launched quite a while ago. We could probably do better than that for not a whole lot of money, especially if we're talking about a self-replicating probe, a maker-bot in space.

      If if takes us 10,000 years to travel to the next star, we WILL be there in 15,000 years. It's just a matter of expanding that 'we' part. The people reading this now will not be there. We will be dead, no choice there. But, our kids... they might have a choice. Their kids probably will.

      There's been life on this planet for 3.5 billion years. That life started banging rocks together around 2 million years ago. We, as a species, have been around for less than 100,000 years. Agriculture for something like 12,000 years, industrial output for less than 1,000, computers for less than 100. What are the odds that another species in our galaxy evolved to roughly where we are within the same 1 million year window? Either they have already been here and are watching us, or we are the first. Either way, the whole SETI thing is a waste of time.

      Light speed limit is physics, not engineering problem

      Mar 30, 2015 at 11:12pm

      The proponents of Active SETI most certainly do not think that light speed is surmountable - that's one reason why they feel it's a safe practice.

      Another reason is that we have nothing here that isn't abundant in a lot of places between here and any potential aliens. Except biology. (Cue crescendo of ominous music...)

      I doubt there are any significant scientists that feel that another Einstein will solve the light speed limit. Some techno-utopians and blue-sky dreamers might, but nothing has even been proposed that wouldn't have its own massive drawbacks (like obliterating your destination coming out of the space-warp-wormhole).

      However, aliens could visit here with advanced robotics. They could have better radiation shielding methods than we can manage currently. They may have a biology that is far more resistant to time and radiation exposure.

      But I disagree with the basic premise that scientists think that the speed of light is surmountable.


      Mar 31, 2015 at 7:29am

      The speed of light doesn't need to be surmountable. All that's needed for interstellar travel is to be able to get close enough to the speed of light for relativistic time dilation to be a major factor.

      Charles Pellegrino and George Zebrowski's novel <I>The Killing Star</I> (now sadly out of print but turns up frequently on the second-hand market) explores the possible danger from aliens finding out about our existence. And yes, it's a disturbing novel.


      Mar 31, 2015 at 7:36am

      There are countless temples around the world with hieroglyphics of aliens and ships, we are a backwater country compared to the rest of this place. Not every life force needs oxygen to survive either, venus could have life on it for all we know.

      The history channel is not a good source of information gwynne, just saying. Travel the world and see for yourself, we have not been alone for a very long time.

      Dustin A

      Mar 31, 2015 at 8:29am

      There is one very important thing to consider that nobody has pointed out yet: the closer you travel to the speed of light, the more time slows down for you. Here’s an example:

      We find an Earthlike planet that’s orbiting a star that’s 100,000 lights year away. At the speed of light, it would take 100,000 years to get there. But that’s from the perspective of someone who’s on Earth. If the person travelling there was travelling in a ship that could travel the speed of light (likely impossible, but just as an example), for them the trip would be over in an instant. They would get there in less than a second.

      It just might be possible, though, to travel at 99.9% the speed of light. So, a cosmic light-speed barrier may not be in itself something that will prevent intelligent beings from being able to travel to distant stars within their own galaxy after all.

      c speed limit is an engineering problem after physics's done

      Mar 31, 2015 at 11:39am

      "We need somebody to do to Einstein’s physics "

      Someone has watched Interstellar... Maybe Murph will do it.

      Newton’s and Einstein’s universe has changed some, in the last fifty years. Dark matter engines might be more practical than chemical rockets. The search for this stuff is one of the major efforts in particle physics today:

      "we will eventually figure out how to do it. And that cheers me up considerably."

      Figuring out how to do it, before we kill/blow-up this planet is the tricky part. Elon Musk said the window of opportunity is limited:
      “There could be some series of events that cause that technology level to decline. Given that this is the first time in 4.5 billion years where it’s been possible for humanity to extend life beyond Earth, it seems like we’d be wise to act while the window was open and not count on the fact that it will be open a long time.”

      "what Einstein did to Newton’s physics"

      Apples still fall from trees - Einstein didn't change that:

      Great, debate. But basically it comes down to a 50/50 chance

      Mar 31, 2015 at 1:57pm

      Just like Stephen Hawkings said, "If aliens visit us, the outcome would be much as when Columbus landed in America, which didn't turn out well for the Native Americans," Hawking has said in a forthcoming documentary made for the Discovery Channel. He argues that, instead of trying to find and communicate with life in the cosmos, humans would be better off doing everything they can to avoid contact"

      Which raises the question, why do we need to contact them? This isn't a race and we're still here and learning enough as a human race. The fact of the matter is, if they are hostile and find us to be a threat, gee i wonder what will happen?. If they aren't, why would they want to share their own technology that they worked so hard towards?

      There's sooo many questions to be asked. But i know for a fact we are NOT ready to communicate to any advanced race right now, we still have racism against each other and hatred towards nations for crying out loud. If they are a peaceful species, they will want nothing to do with us then. But if they are hostile, then that's a scary scenario i don't even want to imagine..

      Eventually something will have to happen as we expand and if life keeps growing and technology keeps advancing it will just be a matter of time. But with no experience at all as a human race in the Universe i would want to be damn sure that our technology at the time is equivalent and/or better than whatever and whoever we meet out there to be %100 safe as a species. My 2 cents :)