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.
to be continued...