Introduction
Recent major breakthroughs in computing and artificial intelligence (AI) may change human existence on Earth and our thinking in astrobiology, especially in relation to the Search for Extraterrestrial Intelligence (SETI).
Estimates of the values of the terms in the well-known Drake formula, which puts together the chances for contact with intelligent life forms, have made great progress in the last decade. The Kepler mission provided estimates of the values of three factors in the equation, which until the Kepler mission were uncertain: the fraction of stars with planets, the average number of planets per star in the habitable zone and the fraction of Earth-size planets. These parameters, are now believed to be of order unity (e.g. Batalha et al., Reference Batalha, Rowe, Bryson, Barclay, Burke, Caldwell, Christiansen, Mullally, Thompson, Brown, Dupree, Fabrycky, Ford, Fortney, Gilliland, Isaacson, Latham, Marcy, Quinn, Ragozzine, Shporer, Borucki, Ciardi, Gautier, Haas, Jenkins, Koch, Lissauer, Rapin, Basri, Boss, Buchhave, Carter, Charbonneau, Christensen-Dalsgaard, Clarke, Cochran, Demory, Desert, Devore, Doyle, Esquerdo, Everett, Fressin, Geary, Girouard, Gould, Hall, Holman, Howard, Howell, Ibrahim, Kinemuchi, Kjeldsen, Klaus, Li, Lucas, Meibom, Morris, Prša, Quintana, Sanderfer, Sasselov, Seader, Smith, Steffen, Still, Stumpe, Tarter, Tenenbaum, Torres, Twicken, Uddin, Cleve, Walkowicz and Welsh2013; Dressing and Charbonneau, Reference Dressing and Charbonneau2015; Wandel, Reference Wandel2017).
Our main ignorance remains in the last three terms: (i) the chances for the evolution of biological life; (ii) the probability of intelligence and (iii) the lifespan of a technological communicating civilization. As may be inferred from the evolution of life on Earth, planets with primitive biological life may be quite abundant (Wandel, Reference Wandel2015; Gale and Wandel, Reference Gale and Wandel2017). However, if the last two terms were small, intelligent and communicating civilizations could be exceedingly rare (Wandel, Reference Wandel2017).
Complex life is a relatively recent development on Earth, where, for approximately 3.5 Gy (about a quarter of the lifetime of the Universe) only simple mono-cellular life appeared (Fig. 1). Life elsewhere may have evolved at a different rate. It is reasonable to assume that many instances of any intelligent life would be more advanced than humanity.
Time line for the evolution of life on Earth. Data from Lyon et al. (Reference Lyon, Reinhard and Planavsky2014) and elsewhere.
Science fiction is replete with humanoids, despite their short appearance on Earth. Homo sapiens has only been around for about 200 000 years, and advanced technology for only two centuries (Fig. 1). Science fiction authors have described advanced and even intelligent computers, nearly always stopping at the inability of computers to carry out advanced pattern recognition, the basis of intelligent thinking. For this, a huge computing ability is considered essential, as in the human brain.
Moore's law
In the last few decades many scientists, futurists and Science Fiction authors have proposed that in the near future computers would have the same calculating capacity as human brains, which have ~1011 neurons, each connected to thousands of synapses. This proposition has been based on projections of ‘Moore's law’ of the evolution of computers. This is an observation that the number of transistors in integrated circuits doubles about every 2 years (Moore, Reference Moore1965). Remarkably, that prediction has held till today, 50 years later (Fig. 2). This advance has probably reached its almost inevitable limit, as a result of the nano-meter size of today's transistors and the impossibility of providing electrical insulation at this scale (Hennessey and Patterson, Reference Hennessey and Patterson2019). However, with the development of quantum computers, even this limit appears to be passable.
Moore's law: the number of transistors per microprocessor versus time. Data taken from Rupp (Reference Rupp2017). We have added the straight line, which shows exponential growth, doubling every 2 years.
Vernor Vinge, a mathematician and science fiction author, introduced the term ‘Singularity’ to describe the convergence of the capacities of the human brain and computers (Vinge, Reference Vinge1993). This term was previously used in mathematics and natural sciences to describe a point where some quantity becomes infinite, or ill behaved. In the context of the advance of technology, the concept received support from eminent polymath John von Neumann, quoted as saying that ‘the singularity will be reached when technological progress becomes incomprehensively rapid and complicated’ (Shanahan, Reference Shanahan2015). The ‘Singularity’ conceptFootnote 1 and its possible consequences were popularized by the futurist author Ray Kurzweil in his book ‘The Singularity is near’ (Kurzweil, Reference Kurzweil2005). Extrapolating Moore's ‘Law’, he estimated that this event would occur in about 2050. Others have suggested that it may come even earlier if quantum computers are realized.Footnote 2
Brains
Neurologists have long been pointed out the poor correlation between brain size and advanced thought. Some collated data on the relative sizes of different animal brains (here, the number of neurons) are shown in Table 1 (data collated from Herculano-Houzel, Reference Herculano-Houzel2009 and elsewhere).
Some animal brain sizes
As apparent from the number of neurons (Table 1), brain size is not well correlated with intelligence. For example, humans have less than half the brain size of the not very intelligent elephants. Of particular significance is the very small brain capacity of insects; here e.g. bees. With just 1 million neurons, bees carry out: Flight; Navigation; Hunting and Gathering; Communication with other bees; Social organization; inheritable home Architecture; preparation of hive Emergency Procedures, etc. (for numerical ability in bees, see Howard et al., Reference Howard, Avagues-Weber, Garcia, Greentree and Dyer2018). Clearly, programming seems to be no less important than brain capacity.
Human brains have developed an extraordinary ability for pattern recognition, which has long been thought to be beyond the ability of computers.
Rapid advances in computers
Recently, computers have been catching up. In 1997, IBM's program Deep Blue beat reigning chess champion Gary Kasparov. However, it was mainly a victory for brute force and the use of a small number of preset strategies.Footnote 3 In 2016, the program AlphaGO, fortified with neural networks and learning modes, defeated Lee Sedol, the Go world champion.Footnote 4
Recently, Google described ‘Alpha Zero’, a self-learning, pattern-recognizing, AI program (Silver et al., Reference Silver, Hubert, Schrittwieser, Antonoglou, Lai, Guez, Lanctot, Sifre, Kumaran, Graepel, Lillicrap, Simonyan and Hassabis2018). Given just the basic rules of Chess, Shogi and Go, this program plays itself millions of times over, selecting and remembering the most favourable winning strategies. The program has beaten human masters in all three games, by using strategies previously unknown to programmers.
The Google program is predicted to be able to solve many hitherto almost intractable problems. For example, in Astronomy – searching data banks for enigmatic radio bursts, in Medicine – reviewing millions of combinations of illness-causing gene and intermediate interactions, as opposed to single-gene errors and in Meteorology – predicting weather patterns from huge data banks.
Brown and Sandholm (Reference Brown and Sandholm2019) have described an AI program, based on Neumann and Nash game theory, which challenges hitherto unbeatable multi-player poker games.
For many years, the concept of quantum-based computers has been predicted as a way forward, once the physical limits of transistors are reached. In theory, a quantum-based computer would be able to utilize an analogue characteristic of multiple positions between zero and one, a limitation of today's digital technology. Until recently, intrinsic difficulties caused by de-coherence, an instability due to the statistical nature of quantum phenomena, and the sensitivity of such computers to vibration, temperature fluctuations and external electromagnetic waves, have prevented practical realization. However, a combination of improved hardware and error reducing software has very recently promised to overcome these problems (Levine et al., Reference Levine, Sharir, Cohen and Shashua2019; Niu et al., Reference Niu, Boixo, Smelyanskiy and Neven2019). It has been predicted that Quantum Supremacy, a term used to describe the point at which quantum computers will out-perform the largest digital computers, could be reached by the end of 2019 (Arute et al., Reference Arute, Arya, Babbush, Bacon, Bardin, Barends, Biswas, Boixo, Brandao, Buell, Burkett, Chen, Chen, Chiaro, Collins, Courtney, Dunsworth, Farhi, Foxen, Fowler, Gidney, Giustina, Graff, Guerin, Habegger, Harrigan, Hartmann, Ho, Hoffmann, Huang, Humble, Isakov, Jeffrey, Jiang, Kafri, Kechedzhi, Kelly, Klimov, Knysh, Korotkov, Kostritsa, Landhuis, Lindmark, Lucero, Lyakh, Mandrà, McClean, McEwen, Megrant, Mi, Michielsen, Mohseni, Mutus, Naaman, Neeley, Neill, Niu, Ostby, Petukhov, Platt, Quintana, Rieffel, Roushan, Rubin, Sank, Satzinger, Smelyanskiy, Sung, Trevithick, Vainsencher, Villalonga, White, Yao, Yeh, Zalcman, Neven and Martinis2019).
These advances in computer capacity and AI suggest that the Singularity may indeed be imminent. It may not come in the very near future but it will arrive, eventually. When it does, H. sapiens, sapiens may move from the bio-chemical realm to the electronic, or to some hybrid combination, with hardly predictable implications for humans (Kurzweil, Reference Kurzweil2005).
While life appeared on Earth some 4 Gy ago, for 3.5 Gy only mono-cellular life existed. Complex life evolved only some 0.5 Gy ago, when a high oxygen atmosphere developed. H. sapiens sapiens appeared just 200 000 years ago, and advanced technology – only in the last two centuries (Fig. 1).
Consequences of the Singularity for astrobiology
The search for extraterrestrial biological life will probably continue along the present lines. Singularity only applies to advanced civilizations, and consequently to SETI. Since some putative extra-terrestrial civilizations have probably had more time than us to evolve, they might have long passed their Singularity.
Once the Singularity is attained, optimal conditions for advanced, complex life may fundamentally change. We may find that the Universe is populated by autonomous, intelligent, space ships driven by quantum-computing devices. If future computers are anything like ours of today (of course they may be quite different), they may prefer dry, non-corrosive conditions, with low temperatures, which would provide a ‘quiet’ electronic environment and enable super-conductivity (Dougherty and Kimel, Reference Dougherty and Kimel2012). They would preferably operate not from the surface of ‘habitable’ planets but in space, perhaps parked in dynamically stable Lagrangian points. However, because of the huge interstellar distances, SETI would not be able to distinguish if broadcasts originated from a planet or rather from a Lagrangian point of the planet and its moon or sun.
If an alien civilization ever visited Earth long ago, it may have parked its beacons in one of the Earth-Moon or Sun-Earth Lagrangian points. An attempt to find such artefacts by photography was unsuccessful (Freitas and Valdes, Reference Freitas and Valdes1980).
Furthermore, post-Singularity civilizations may not be communicating by radio waves but rather by quantum entanglement, which is only in its very first stages of development on Earth (Ursin et al., Reference Ursin, Tiefenbacher, Schmitt-Manderbach, Weier, Scheidl, Lindenthal, Blauensteiner, Jennewein, Perdigues, Trojek, Ömer, Fürst, Meyenburg, Rarity, Sodnik, Barbieri, Weinfurter and Zeilinger2007; Kumar et al., Reference Kumar, Lauk and Christoph2019). This may provide yet another solution to the Fermi paradox, or at least to the Big Silence problem in SETI.
As for humanity's future, perhaps the superior brains of the new computers will solve Earth and humanities many problems. Science Fiction is replete with predictions, some reasonable, some disturbing, such as that mortality can be overcome by downloading the brain's contents to computers. In 2014, Stephen Hawkins stated in an interviewFootnote 5 ‘The development of full artificial intelligence could spell the end of the human race’. In other words, AI and the Singularity may be humanity's greatest and last advance.
