I will restrict the analysis only to the galaxy, since any conclusions can be scaled up and extrapolated to the larger scale. The apparent question is why we do not see intelligent life in the galaxy, usually framed as the Fermi Paradox. This is an apparent contradiction between our theoretical expectations for intelligent life in the galaxy and our observations that we do not see any.
We begin this essay by clearly stating what the Fermi Paradox actually is. A paradox apparently exists between our theoretical expectations for intelligent life in the cosmos, based upon our measurements of stellar structure, age, composition, type, evolution, and our observations which are in apparently conflict with this expectation. This suggests straight away that there is something wrong with one or both or our two assertions: (1) that our theoretical models are incorrect (2) that are observations are incorrect. In order to bring them both into alignment, a detailed and rigorous revisiting of these assertions is required.
Firstly, we can define a paradox as a statement that apparently contradicts itself, such as a logical paradox which is an invalid argument. A paradox will often have revealed errors in definitions that are assumed to be rigorous. Because of this, I do not see the Fermi problem as a logical paradox, but more of a logical contradiction in terms. That is to say, that in classical logic, a contradiction consists of a logical incompatibility between two or more propositions. It occurs when two conclusions which form the logical, usually opposite inversions of each other. Hence I like to reformulate the Fermi Paradox as the Fermi problem.
Instead, it is better to look at the Fermi problem, from the standpoint of a mathematical axiom. An axiomatic system is any set of axioms from which some or all axioms can be used in conjunction to logically derive theorems. A mathematical theory consists of an axiomatic system and all its derived theorems. So with the Fermi problem, any statement which asserts the presents of intelligent life in the galaxy is a theorem, which must derive from the axiom that the galaxy is capable of hosting intelligent life in the first place. We know that this this axiom is true, because we are here, and so we represent the manifest evidence for the starting point of reasoning, to be accepted as true without controversy. Given that we exist, we are left to ask do others exist? This then leads to the development of a hypothesis as a proposed explanation for the phenomenon. And in the Fermi problem there are two forms of hypothesis that are proposed. The first hypothesis is that the galaxy is capable of hosting more than one intelligent life form on separate worlds around other stars. The second hypothesis is that we have the technological capability to measure the presence of such intelligent life should it exist. But these are not logical paradoxes, merely mutually exclusive and independent hypothesis which can be tested, in order to develop full theorems. But as we shall see, there are numerous issues with our handling of both hypothesis which make reasonable progress not sensible, due to the logical fallacy of the questions and how they are framed.
The first point of our analysis is simply to ask if interstellar travel is even possible. Because if is does not appear to be, then that would be the explanation for the Fermi problem. However, given that the 1970s Project Daedalus study conceived of a fairly credible machine, despite its flaws, it is not an unreasonable interpretation of this work that in the future (even if centuries or millennia) we can design a much improved machine which is far more credible, and therefore interstellar travel does appear to be feasible in theory, as a proof of existence problem. This conclusion is amplified even further by the fact that Daedalus was just a method via fusion, and since then we have conceived of a dozen other methods by which a machine could be propelled to the stars – which is a form of validation for the original Project Daedalus conclusions that interstellar travel was possible in theory. This is a conclusion one might choose to only apply to robotic vessels, but we have also conceived of various methods by which biological crews may be transported (e.g. seed ships) and so this conclusion would seem to be applicable to human missions too, at some point in the future. So given that interstellar travel appears to be feasible in theory, we must look for other solutions.
We also live in an age where countless exo-planets are now being discovered around other worlds. But one fact that has not been considered is that if an alien species never discovers a science that goes beyond simple chemistry, and they live on a large mass planet, then they will never be able to leave that planet due to the enormous escape velocity associated with the gravitational well. To assess this, one would need to know more about the mass function of Earth type planets and Jovian type planets that exist in the galaxy, in order to inform any statistical assessments.
Certainly, our observational telescopes are improving our knowledge of the universe every day, and giving us insight to inform our ‘best guesses’ about what may be possible. But it is also clear that sending starships too far away destinations, as a form of in situ reconnaissance, will add valuable to such an effort as a form of scientific enquiry.
We can look at the problem by examining two extremes, and then everything else in between. These two extremes are that we are the only intelligent life in the galaxy, or that we live in a crowded galaxy. The idea that we are the only intelligent life in the galaxy, and therefore the first intelligent life to arise in the galaxy, has been argued by many. This includes Viewing in his paper “Directly Interacting Extraterrestrial Technological Communities” (JBIS, 28, 735, 1975) as well as Hart in his paper “An Explanation for the Absence of Extraterrestrials on Earth” (QJRAS, 16, 128, 1975) and Tipler in his paper “Extraterrestrial Intelligent Beings Do Not Exist” (QJRAS, 21, 267, 1980). The idea that we live in a crowded galaxy, has been argued by authors such as Shklovskii and Sagan with their book “Intelligent Life in the Universe” (Holden Day, 1966) and also Sagan and Drake in their paper titled “The Search for Extraterrestrial Intelligence” (Sci.Am., 232, 80, May 1975). Bond and Martin examine these two extremes succinctly in their paper “Is Mankind Unique? – The Lack of Evidence for Extraterrestrial Intelligence” (JBIS, 36, pp.223-225, 1983). Let us consider both of these extreme possibilities in turn, before we consider everything else in between.
Hypothesis 1. We are the only intelligent life in the galaxy. This seems to be highly improbable, purely from a statistical point of view. That said, evolution by natural selection does allow for spontaneous mutations that have never been seen before. It could be that intelligence is a form of evolutionary mutation and we are merely the first to exhibit it. Then again, there are also examples in the animal kingdom of Earth where two species, having no connection to each other on the evolutionary chain, (different lineages) have a similar design element or analogous structures, because nature has found that solution twice for those two different species – this is known as convergent evolution – as opposed to homologous structures or traits which do have a common origin. An example of this would be vertebrate wings as forelimbs, such as used on bats and birds – they are analogous and resemble in each in the same way, and they fulfil similar functions, but their roles in flight have evolved separately. On this basis, looking for evidence of a separate biogenesis on Earth or outside of the Earths biosphere is entirely reasonable. In particular, since mutation by natural selection favours those mutations which are beneficial, and natural selections appears to guide the evolutionary processes to incorporate only the good mutations into the species and expunge any bad mutations. Given that intelligence appears to be an advantage to survival, it would be a surprise if nature has not allowed this mutation to occur in other species. Overall, it would seem fair to conclude that the idea of there being only intelligent life on this world is mainly a problem for biology to address, and not the other disciplines of science.
In addition to this, biology tends to define an organism as any contiguous living system, and it is generally the consensus that all types of organisms are capable of some degree of response to stimuli, reproduction, growth and development and homeostasis – the so called properties of life. An organism may consider of one cell (unicellular) or more than one cell (multicellular) and they are typically of microscopic size and hence termed microorganisms. There will also be an ecological connection between any organisms and their environment. Biological classification will also tend to cite the following organisational groups as a form of hierarchy: atoms, molecules, macro molecules, molecular assemblies, organelles, the cell, tissue, organs, organ systems, organisms, populations, species, community, biosphere. If we are to fully understand the apparent limitless pathways of evolutionary biology and the application of natural selection, it might be prudent to look for evidence of these organisational types operating in unexpected systems. This could be in apparent ecological systems or even astrophysical systems. Who is to say that the entire galaxy is not in some way operating, in analogy if not directly, as a giant organism? Overall, we need to establish a greater dialogue among the many disciplines of human thought to ask a broader question about what is life.
Considering the question of biology in the Cosmos, it seems to me to be a highly arrogant position, to assume that biology has only occurred on one world in a vast and expansive universe over its 13.8 billion years of history. This position would seem no different to me than the age old assertion that the Earth was the center of the solar system and thereby the universe. The reason it takes so much longer to address the biological element to this apparent anthropocentric thinking, is that the distance between the planets and by implication the stars is so much further away, and it is only in fairly recent times that we have achieved the technological capability to begin to ask this question when we became a space fairing species. My own view, based on statistical arguments alone, is that not only has intelligent life been to our solar system, but they are here now – but the nature by which they are here is non-trivial to unravel, given our biased thinking, preconceived notions, assumptions about them, lack of knowledge, and the poor manner by which we frame our questions such as the Fermi Paradox.
Hypothesis 2. We live in a crowded galaxy. This has a much larger suite of options in terms of explanations, and it is mainly a problem for the disciplines of physics, astrophysics and moral philosophy. If we take as a priori assumption that we live in a crowded galaxy but are not observing or seeing any evidence of intelligent life, then we can examine the problem from three levels of investigation. The first is observations, the second is analysis and interpretations, and the third is moral philosophy as applied to extraterrestrial socio-cultural groups.
When we say we are not ‘seeing’ evidence of intelligent life in the galaxy, we have to ask what is meant by ‘seeing’? Principally, our only mechanism for interacting with the Cosmos over large distance scales is via the observations of light, be it through radio waves, micro-waves, infra-red or optical. This means that we are interacting with the universe purely through the electromagnetic spectrum and then trying to use that information to interpolate about what is taking place to manifest that specific spectrum that is observed. So the first thing we could do is to expand our range of observations, to encompass the entire electromagnetic spectrum, but also to go outside of it to observe other phenomena. We could also examine the vast animal kingdom of the planet Earth for examples of species that have senses or interaction mechanisms that are not just through the electromagnetic spectrum, and then to hypothesise for alien biology’s where nature may have found a similar solution. Overall, we need to vastly expand our horizons for what we are trying to ‘see’ and in particular to avoid a human centric perspective.
This also includes a re-examination for what we observe with light and whether our assumptions about homogeneity throughout the Cosmos are correct. This Copernicus principal has served us well in past centuries, and there are good reasons to think that the universe is homogenous and uniform on all scales (although fractal modelling of the large scale universe might suggest a breakdown in this model on extra-galactic scales). But it may not be in certain parts, and if that is the case, then our observations will simply be in error.
As well as ‘seeing’ we can try to access other senses by which we might interrogate these distant worlds. Currently, the laws of physics appear to prohibit us from smelling, tasting or hearing them. But certainly we can touch them, if we have the courage to send out reconnaissance probes and land planetary landers onto the surface of any bodies in orbit around those distant stars.
So let us say that we have then exhausted all options in terms of observations, presumably after a multi-decade program of work and we still conclude that we are not ‘seeing’ any evidence of intelligent life in the galaxy. The next stage is to question our methods of analysis and interpretations, of the data that we are observing. It is entirely possible that the evidence is staring us in the face, but we are ignoring it because it does not fit within our pre-conceived notions. This could be for our definitions of life or intelligent life for example, and living systems may be much more ubiquitous that is imagined within our limited definitions. We also need to examine our methods, such as the requirements of the scientific method for reproducibility and falsifiability. If an event cannot be observed again, it is immediately disregarded and thrown out. When in fact, this is inconsistent with the large scale belief of human history – i.e. many claim there was one biogenesis event which gave rise to all living things. We also have a tendency to throw away so called outliers, because they do not fit the statistical trend of a data set. We should go out of our way to scrutinise those outliers and not be so keen to disregard them because they do not fit our preconceived notions of how things work. There is also a bias in science, such as a rush to conclude that an observation must be explainable by some astrophysical event. Although this is not an unreasonable position to take, alternatives should be considered, no matter how wild, and the door should never be closed on what possibilities there may be.
One example of data that may be staring us in the face is the famous 1970s ‘Wow!’ signal, for which a 72 second radio burst was observed from one of the detecting horns, never to be observed again. Scientists have spent much time examining the signature and the apparent location of the source, on the assumption that it is either an astrophysical event or ET attempting to communicate with us via radio beacons. All nearby terrestrial sources have been ruled out. Yet, one possibility that may explain the energy emission is that it is in fact a mobile source, as in a starship engine signature at a distance. Similarly, there are at least 35 other similar signatures in the astrophysical data base which do not receive attention, but may be explainable by this cause. Yet because it is considered too fantastic a possibility, the apparently free thinking and open minded SETI community which has spent much of its time examining the data, doesn’t even consider this option. Some earlier attempts have already been made to examine what long range starship signatures may look like. This includes the Zubrin paper “Detection of Extraterrestrial civilizations via the Spectral signature of advanced interstellar spacecraft” (Progress in the Search for Extraterrestrial Life, ASP Conference Series, Vol 74, 1995). This idea has also been examined by Viewing in his paper titled “Detection of Starships” (JBIS, 1977).
So let us say we have now greatly expanded the scope of our interpretations and analysis, and even after this program of work we still conclude that we do not see evidence of intelligent life in the galaxy. On the priori assumption that intelligent life does exist, but we are not seeing it, this leaves several possibilities, most of which comes down to forms of moral philosophy, given the nature of the uncertainties involved in such futuristic scenario building.
The first is that there is some agreed consensus not to interfere with our cultural development. Alternatively, there could be a genuine fear to interact with us, due to our immature nature, or the unwise manner by which we use our technologies. We might also not be seen as good custodians of our own planet, so what example are we setting for how we might conduct ourselves out there. We can take an analogy of a family living in a street, and there is another house in the street with a family of convicted felons, known liars, instigators of violence, overall bad company; from which we might choose to cross the road rather than interact with them. Another example could be there is a family which are perfectly fine in terms of obedience to law and order, but they are from a different culture to us and they have strange ways which are alien to us and we have tendency to fear that which we do not know or understand. Intelligent life in the galaxy may choose to avoid us for any one of these reasons, which are all variations on the zoo hypothesis.
Alternatively, it could be that we are simply not of interest to any advanced intelligent life form, the same way that we walking down the street would not be interested in an ant crossing the road. This would be the case if our cultural and/or technological development was so far apart, of order a million years or more. It could also be the fact that because of the huge gap in development, that they cannot see how to communicate with us, because we are simply too primitive. Another possibility related to this is the technological runaway effect, where some form of full blown transcendence or AI convergence has been achieved by those advanced alien societies, thus exacerbating the cultural and technological divergence between us. Such things are imagined in the concepts of von Neumann probes, self-replicating machines.
It is clear therefore that we need to question the scope of our observations as well as reassess our interpretations of the data we are measuring, if we hope to have any chance of detecting evidence of intelligent life in the galaxy. But ultimately, any life forms travelling across space will be using starships of a form. It is therefore highly prudent to widen our imaginations as to what form they may take, as well as what observable emissions they may make which we can detect – accepting that the known laws of physics will apply, or the unknown laws of physics will eventually be elucidated by such studies. The act of designing starships is also a self-fulfilling prophesy in that by imagining them we are inching forwards towards their fruition. Hence we come to my own motivation for the starship, and why I am pushing it so hard – to increase our chances for finding them and thereby understanding if we are alone, or in a crowded room, and all of the profound implications of that, particularly for religion and philosophy.
We have explored the two extremes of a crowded galaxy and a galaxy with only one example of intelligent life – us. But there are obviously lots of other options in between these two extremes, such as there being two intelligent species in the galaxy, or dozens, which would not necessarily meet either of the definitions of the two extremes examined above. So it may be that the galaxy is populated by intelligent civilizations among its 100-400 billion stars, but they are just not frequent enough to notice each other. This comes down to a question of distance and time. Given the galaxy is 100,000 light years across, and the average star distance is around 5 light years, this means that in any interstellar crossing a starship will encounter 100,000/5 = 20,000 stars on its line of sight path. Now it will obviously pass within a few light years of others on that journey, so let us be charitable and say it will come within observational distance of around 100,000 stars on one galactic crossing. That is still only 100,000 / 100 billion = 0.0001% of the entire stellar population. And so if there are say optimistically even as many as 100,000 intelligent civilizations in the galaxy distributed over the 100,000 LY diameter spiral, we are looking at a very low probability of interaction.
The other issue is a temporal one. In that even with say 100,000 intelligent civilisations in the galaxy, with each stars separate evolution, planetary formation timescale, the rise of life, then emergence of intelligent life and eventually a space based culture, these events will not all happen in parallel. Some may be overlapping, but it is more likely that there will be limited windows upon which to discover other intelligent civilizations that have a similar level of technological development to us. By similar, I mean within one million years, because anything less or more than this has implications for interest and also whether it is possible to conduct meaningful communications between worlds. Overall this is a question of probability and population size which feeds into the likely hood of interaction.
Another possibility is that we are once again anthropomorphising the problem, mapping human hopes and desires onto an extraterrestrial species. Our primary driver for exploration and discovery is curiosity and the growth of industry. But an intelligent extraterrestrial species may not have the same motivations of us. They may choose to cross the galaxy but for entirely different reasons, and on their journey not even be listening out for the presence of others. Survival is likely to be a primary driver for exploration, but we do not know this for sure.
Finally, if we do live in a crowded galaxy, then any reasonable analysis of the number of stars, number of planets, the evidence for life formation on Earth, the age of civilisations, certainly makes it highly probable that they, meaning ET, are already here in some form, or are at least aware of us and perhaps observing from a distance. Certainly, if any life is found on the planets within our own solar system (such as on Europa or Mars) as evidence of separate biogenesis, then the probability of life in the galaxy will increase too – and we must conclude that not only have they been here but are here now in some manner. This is not to support the vast claims of UFOs and alien abductions, many of which can be examined by any reasonably thinking person and dismissed as mistakes, misinterpretations, fantasies or fabrications. That said; there is a small quantity of those observations, perhaps less than 0.1% which is of interest and could be examined further. But those incidences are lost in the noise of the fantastic claims, and also in the difficulties of distinguishing from genuine sightings and government black programs which are by their nature secretive and explicitly clandestine – and sometimes to the extent that government programs have been used as cover stories for reported sightings therefore making proper objective analysis difficult.
What we might consider however, is that if we presume an intelligent species is observing us from a distance, the same way that we observe the animal kingdom from a distance, or the same way that our telescopes are now looking for evidence of habitable planets around other stars. It is entirely likely, given the advanced state of their technology, that they can observe and therefore learn a lot about us, including from emission signatures to indicate evidence of wide scale industrialisations, or the development of nuclear based technology. When the world’s highest atomic explosion was detonated by the Russians, it achieved a yield approaching 60 Mtons, and it was so energetic that it created two new elements, later named Einsteinium and Fermium. It is these sorts of signatures that would be of interest to any observing civilisation, as evidence that we are maturing technologically. In particular since nuclear technologies have myriad applications to starship power and propulsion systems. It is possible, that they would place ‘sentinel’ type probes in the outer limits of our solar system as a form of warning beacon, as envisioned by Arthur C Clarke’s “2001 A Space Odyssey” or his short story “The Sentinel” published in 1951. The idea of searching for extraterrestrial artifacts which might have this function has been suggested previously by Freitas in his 1983 paper “The Search for Extraterrestrial Artifacts (SETA)”.
Once we have attained technological prowess, they would then be interested in what direction we were going to go, towards technological annihilation and/or stagnation or technological maturity. If it appeared that we were in fact heading towards technological maturity, then the next question they might ask is when will we achieve space capability, in terms of sending missions to the outer edges of our solar systems and eventually to the stars – in effect when are we coming?
We have in fact made this question easy for any advanced monitoring ET to assess, due to the invention of the World Wide Web, itself perhaps a precursor to a form of large scale artificial intelligence not unlike a Matrioska brain concept. Given that the information from the web is beamed via space satellites, accessing that information may present an easy way to retrieve data about our civilisation – and by the way, this is another area we could examine for evidence of ‘interstellar hacking’. One area they might be interested in is at what point we start to express interstellar ambitions, towards the stars. They would be interested in our designs, our concepts, or our philosophical and moral perspectives, and even our analysis of their existence, such as this very document that I am writing. In which case, all of the interstellar organisations and their principal protagonists and advocates, would also be of interest to them – and with that chilling thought; it’s time to turn off the lights and go back to a candle and type writer.