“If we were made of some rare isotope of Bismuth you might have an argument for us being alone in the cosmos”
One of the things that often comes up when discussing topics related to space or future technology is the Fermi paradox. Quite simply put, this begs the question that if the universe has been around for billions of years, where are all the aliens? There’s been ample time for them to evolve and either travel to our planet, or for the radio traffic they generated (perhaps millions of years ago) to reach us and be picked up by the likes of the SETI institute.
Figure 1: Where’s ET?
As a result the Fermi paradox is often cited by those who favour the rare earth hypothesis (REH). This states that the chances of a planet evolving life, never mind intelligent life, are so rare its highly unlike to have occurred twice and certainly any other species will likely be a very long way away (as in, that we are probably the only intelligent life in this galaxy). We are only here because we live on a planet with a very stable orbit, in exactly the right orbit, a planet with a magnetic field and volcanic activity, we’ve a large stabilising moon (which stops the planet wobbling around, causing severe climate change) and Jupiter acts like a sort of planetary hoover, disposing of asteroids and comets that would lead to us getting hit more often. And had that big impact that killed the dinosaurs not happened, then neither would we have evolved, or a few dozen other events over the last few billion years.
Figure 2: An outline of some of the factors REH cite as essential for the formation of the earth and our evolution
This idea has never sat well with me. Indeed this whole concept of the REH seems to have been dreamt up by someone who doesn’t understand statistics. Any event, no matter how unlikely, will still occur over a suitably long enough time period, if a sufficient number of trials are held. The odds of winning the lottery are extremely remote, yet every week someone generally does win it. The odds of being killed in a plane crash are also very remote (you are more likely to slip in the shower on the day of the flight), yet planes do crash on a pretty regular basis and people do die (a few thousand every year are killed in plane crashes). Indeed the whole reason plane travel is so safe and cars and other products are increasingly much safer is precisely because we engineers understand these statistical truths and factor this into our designs (usually by making sure that no single point of failure should result in catastrophic failure of the entire system).
There is also a sort of Sliding Doors (a reference to the film by the same name) element to the REH. In that it is assumed that there is only one possible outcome that will yield a positive and all others possibilities lead to disaster. Its like trying to argue that you have to bake a cake exactly the way you did it last time. That if you don’t start at exactly 18:25:03 and if you don’t take exactly the same amount of time to prepare ingredients and you you have to put in exactly 54.56g of sugar and 303.56g’s of flour and the oven must be set to exactly 222.43 °C and you bake for 1 hr 23 mins (rather than the 220 °C and 1.5 hrs the recipe says), otherwise baking a cake is impossible. As Douglas Adam’s in the Hitchikers Guide quibs, if you take the naysayers at their word the theoretical population density of the universe is zero and thus anyone you’ve ever met (including yourself) are all elements of you’re own over active imagination.
A useful counter to the REH is Jack Cohen and Iain Steward‘s “What would a Martian look like”. Their key point is that life on earth is a lot more diverse and capable of surviving in much wider extremes than we often realise. And as a consequence alien life could indeed be very alien to us indeed. An earth that was a bit warmer, colder or has a more variable in climate would be bad news for us or the organisms we evolved from, but there’s plenty of life on earth that would not be the least bit troubled by this. Indeed, given that such conditions would eliminate the competition (us!) they’d positively thrive. The authors also go on to argue that our narrow definition of a “habitable zone” might not be accurate, as there might be different habitable zones for different forms of life. Speculation about the possibility of life on Juipter’s moon Europa does pretty much blow the concept of a narrow “habitable zone” right out of the water.
Figure 3: Real aliens could be very alien indeed
Of course this brings us back to the Fermi hypothesis, if life isn’t extremely rare in the universe where are all the aliens? Well firstly, as I discussed in a recent piece, space flight is very difficult. Once we eliminate such fantastic sci-fi as warp drives, anti-gravity or transporter beams, getting from one star system to another is a monumentally difficult task. That only a tiny handful of species that evolve might actually do this isn’t that crazy a suggestion. And the odds of us bumping into any of these aliens (given the vast distances) are pretty low. Indeed this is probably closer to the point Fermi was actually trying to make than the rare earth hypothesis. But what about radio traffic, surely we should be picking up masses of radio traffic from various alien species?
Well not necessarily. Put it this way, when was the last time anyone reading this used a radio? Sent a telegram recently? Probably not. Most internet traffic, telephone calls and TV signals now go via fibre optic cables. And its likely that over the next hundred years our communications technology will change radically, using directional lasers (essentially fibre optics without the cable), short range wi-fi or even perhaps neutrinos. Bottom line, if you pointed a dish at the earth 150 years ago you’d hear nothing but static. Point one at the earth in another hundred years and you’ll probably also hear nothing but static (of course if Trump has his way you’ll hear only static in a year or two’s time!).
Assuming other species follow a similar trend, then the window of opportunity during which we could detect another alien species (by current means) is likely to be very narrow, 200-300 years, which is practically a rounding error on the time scales of the universe. The chances of two species (ourselves and someone else) both evolving to a point where we both have similar communications technology at more or less the same time, yet we are both sufficiently close enough to one another to establish communication links, before one goes off the air. Well that’s pretty remote.
Figure 4: Radio telescopes might not be the best means of finding ET
And radio signals don’t travel an infinite distance. The further away you are from the source, the larger the size of the dish you’ll need, the more sensitive instruments need to be. Beyond a certain distance it would be impossible to hear any of the signals we generate and thus impossible for us to eavesdrop on any aliens.
The drake equation is often cited in relation to this topic and what essentially I’m saying is that we might need to re-calibrate the last two factors in this equation Fc (the fraction of civilisations who attempt to communicate) and Fl (years during which communication occurs). Many assign values to these in the order of 1 and 1e9 respectively. I’d argue a figure of 0.001 (reflecting the low probability of them communicating in a way we can intercept and the probability of such a signal being actually picked up) and 200-300 years instead. Run those numbers and even assuming a reasonably optimistic values for all other factors, you get a very low result, perhaps only a handful in this galaxy, even in a scenario where we are otherwise estimating maybe a million civilisations within our galaxy alone (not that I think there are that many, I’m just pointing out that even if they existed, we are likely to encounter “technical difficulties” in communicating with them).
Certain types of signals would be detectable at a considerable distance. For example certain types of focused radio signals used to contact distant spacecraft or for planet to planet (or perhaps star to star) communication. There is also the concept of using focused and powerful beams of microwaves to shunt power from orbiting solar power satellites either to the ground (for electricity) or to propel distant spacecraft. Again, these would be detectable at a considerable distance.
However the “flash light” of such signals would be very narrow and the odds of us seeing such a signal are very low and it would only be fleeting, not unlike the infamous “Wow” signal. More recently there’s been the topic of Fast Radio bursts (FRB’s), which potentially fit the signature of these sorts of signals. Fraser Cain from the Universe Today, discusses the ongoing investigation into FRB’s here. Suffice to say, it probably some natural phonomeon, but scientists have yet to come up with a conclusive explanation.
Then there’s the matter of deliberate communication. We’ve blasted out the odd signal ourselves that would be detectable some distance out, so surely it must have occurred to some aliens to do the same? Well no, not necessarily. Why would a civilisation which is perhaps tens of thousands of years old, maybe even millions of years old resort to using a technology they briefly employed thousands of years ago when they now have far better technology available?
It would be the equivalent of the Chinese trying to communicate with the Russians by lighting beacon fires or Trump sending a telegram (oddly enough Western Union only stopped doing those in 2006) to Putin (likely saying, when can I defect?). And as for aliens looking out for our radio traffic, that would be like the US spending billions on new high resolution cameras on its spy satellites on the off chance the Iranians go back to using signal flags to convey military intelligence.
It probably won’t occur to any alien species to do this, and they’d be well aware that if they did find anyone it would be primitives like ourselves. It would be like us going out of our way to communicate with some uncontacted tribe in the Amazon rainforest and I don’t see anyone rushing off to do that.
Indeed, one possibility is that alien civilisations are deliberately avoiding or limit any transmissions that might be picked up by primitive civilisations like ourselves. They would be well aware that the bulk of civilisations in our stage of development are going to be relatively dangerous (fighting wars, following crazy religious belief’s, have despotic leaders, etc.). Most civilisations in our stage of development probably eventually destroy themselves (via environmental degradation or war). Only those who learn to live within their means and to co-operate peacefully will survive beyond a certain point. So it would make sense to give civilisations like ours a wide berth until they’ve evolved to the point where you can get some sense out of them.
So perhaps a different approach is needed. Looking beyond radio traffic, or perhaps trying more direct means to search for ET. And fortunately some surveys along these lines are already being conducted.
A notable candidate is Tabby’s star, which has produced some unusual Kepler data. While this is likely to be nothing more exciting than debris from a planet that breached its star’s Roche limit. But its been speculated that the star might have a Dyson swarm around it (an alien mega structure!).
Figure 6: There is considerable speculation about Tabby’s star, likely just debris, but could it be an alien megastructure?
We’ve already found a number of exoplanets, some of them in orbits within the habitable zone around their host star. Trappist-1 for example might have 4 planet’s in its habitable zone (that said, remember what we said earlier about habitable zones, it could be broader than we assume and if a planet lacks an atmosphere then it may make little difference which orbit it is in). Within the next decade the next generation of space telescopes should allow us to scan these planets and inspect the atmospheres of these targets for signs of life, e.g. oxygen, water, methane or carbon dioxide. And of course efforts to find life in our own solar system continue.
Figure 7: Trappist 1 has several exoplanets that join a growing list of potentially life bearing worlds…
Needless to say if we find any hint of life (regardless of how primitive), either in our own solar system or those nearby, then basically the rare earth hypothesis is DOA. Two positives in this small corner of the galaxy, in a universe with more stars than grains of sand on a beach its pretty reasonable to conclude that alien life is fairly common, although intelligent alien life is another matter (between Trump and brexit I’d question whether it exists on earth!).
Figure 8: ….which future space telescopes might allow us to detect
This also raises another question (this is the problem with any space related topics, you end up with more questions than answers), are aliens aware of our existence? There are some who argue we should try and hide our presence, just in case any aliens show up looking to eat our leaders (well if they are here for Trump, I for one welcome our new alien overlords).
Jokes aside, the cat is out of the bag and has probably been so for millions of years. Using similar technology to what we are now working on, any aliens in our neighbourhood would probably be aware by now that the earth has an oxygen rich atmosphere. The smarter ones might well notice the increased air pollution and carbon dioxide levels indicating industrial activity. And later on, the fallout from atmospheric nuclear tests, indicating we’re tinkering with nuclear technology. So that ship sailed along time ago.
And since we’ve mentioned the topic of invading aliens, aggressive aliens are probably unlikely. And they certainly won’t show up with ray guns in city sized flying saucers. There’s a host of far more effective military tactics a space faring society could adopt, e.g. putting a mass driver on a kuiper belt object and using it to fling large rocks at us. A couple of months of that and you could annihilate every military base, industrial area and city on the planet without having to risk any ground troops or even air/space forces.
So why aren’t they here? Well A) they may not have the technology to get here. B) oddly enough they are reluctant to make contact with a bunch of nutters like ourselves. Or C) Given that it would take hundreds of years for light to travel from our star to theirs (and thus if say they were 1,000 ly’s away they won’t be aware of possible industrial activity on earth yet), it would take some time for them to learn of us and longer still for them to travel here or send a signal.
For example, let’s suppose there is a Dyson sphere at Tabby’s star. Even if that were the case, we shouldn’t expect any sort of signal until at least 4,000 AD at the earliest. Even if someone with interstellar travel was absurdly close, e.g. Trappist-1. And even if on the first sign of nuclear testing in the 60’s (which they would only have observed in the last decade or so), they jumped in a spacecraft straight away and headed towards us, even assuming a speed of say 0.5 LS (and of course we’re assuming that its possible to travel that fast, this again is probably more the point Fermi was actually trying to make) they’d not arrive until the latter half of this century. Of course if they are further away, or can’t travel anything like that fast, these time scales lengthen considerably.
So does this mean that anyone involved with SETI is wasting their time? Well no. Everything I’ve said is speculative, as is everything that is said by SETI’s critics. And as noted they have constantly changed tactics, so just because the first few attempts failed doesn’t mean further efforts will also fail. Without some concrete evidence either way we can’t be sure. Frankly if we’re going to spend hundreds of billions a year for a bunch of guys to sit in a bunker waiting for orders from the president to start world war III (then when Trump calls, point out to him that no we can’t nuke the New York Times just because they said you’re a tax cheating Russian spy), then we can spare a few million for SETI activity.
And one has to look at the bigger picture. One thing I liked about the old computer game civilisation was how if you built the SETI institute it doubled the output of all of your science labs. Big science projects often lead to developments in related fields with all sorts of unexpected benefits. If it weren’t for projects like SETI or CERN, you won’t be reading this blog post.
Playing the long game is key. As noted these FRB’s, or the Wow signal (or the mystery of Tabby’s star), don’t add up to much, unless all natural phenomenon can be ruled out (and they can’t). But if say, in a decade’s time, similar signals were to be received and we still can’t come up with a convincing explanation as to what natural phenomenon could be behind them, well that’s a different story.
Of course this also suggests we may never get a definitive answer to this question. Short of aliens landing on the Reichstag lawn (post-Trump and brexit Germany is now leader of the free world), we’ll never be 100% sure. We might get to the stage where scientists are all but certain that one of the Trappist-1 planets has an oxygen rich atmosphere with signs of advanced life, or we’ve yet to come up with a conclusive answer to FRB’s despite decades of trying. All of this would be a lot of smoke, but we won’t be able to call it a fire.
So all in all the answer to the Fermi paradox can perhaps be summed up as “like Duh!”. Weighting up all the different factors it would be more likely than not, even in a galaxy with millions of other civilisations that we won’t have heard from any of them.
And for the record, while I don’t discount the possibility of advanced alien life, I would personally guess that there aren’t nearly that many and if there are any out there, they are probably some considerable distance away. They might be aware of our presence, or they might not (given the hundreds of millions of stars, that our planet was simply overlooked isn’t that unlikely). They might simply not care. Such contact might be forbidden under the terms of some sort of intergalactic treaty. Or the invasion fleet might well be on its way (what’s the bet if aliens ever did show up that the Daily Mail will say they are only here to claim benefits). Or its possible that having witnessed us polluting our atmosphere and testing nuclear weapons, they’ve concluded we’re doomed and plan to wait till after the inevitable apocalypse before moving in.
The point is that there are several perfect rational explanations without us having to torture statistics to get the answer we want.