"What would last a hundred million years? Not much, but there are some things, like nuclear waste. Or any sort of biotechnology that has knock-on effects: If you tinkered with genomes a hundred million years ago, the traces of that would still be with us today. Or any large-scale quarrying: If you chopped up an asteroid in a very distinctive way, that'd still be orbiting. Who knows when we might stumble across such a thing? We'd say, the aliens came, and they're gone, but they left a calling card inadvertently. That's going to be one of the biggest discoveries in the history of mankind."
– Professor Paul Davies
For the last fifty years, a relatively small band of scientists have dedicated considerable efforts to the search for extraterrestrial intelligence – SETI. Probably most readers will be familiar with the SETI Institute, founded in 1985 and the most prominent hub for focused efforts to detect alien civilisations. Due in significant part to the technological limitation of the time, the scientific search for extraterrestrial intelligence has primarily centred on monitoring the cosmos for structured radio emissions. The aim is that radio telescopes on earth will detect signals from distant planets at a technological level like ours. Detecting civilisations producing radio transmissions in our remote past and finally reaching our solar system.
It is not unreasonable to think that somewhere out there are, or were, intelligent beings that used technologies akin to our own and produced radio signals. However, we must consider the outrageous odds against a radio signal fortuitously travelling in our direction, at this moment in the vastness of time, with our radio-telescopes monitoring the right section of the vast sky. All of this is further complicated by the background noise of both earth and space, with us having little idea what an intelligent signal might be like. The chance level required is somewhat akin to finding a particular needle in an ocean of pins. The shrewd gambler wouldn't put a dime down on this detection happening even in the next thousand years.
We are reminded of the concerns expressed by the University of Cádiz neuropsychologists Gabriel de la Torre and Manuel García on radio signal hunts detracting from preferable technosignature indicators. However, they are not the only scientists who see an urgent need to move beyond a narrow focus on radio waves. Long-time SETI Post Detection Task Force director Professor Paul Davies echoes the concerns of the University of Cádiz neuropsychologists:
"I think we need to get away from the idea of leaving this [SETI] to a small and heroic band of radio astronomers and try and spread the burden across the entire scientific community. I think all the sciences can contribute, and I'll give you some examples," says Professor Davies.
It should be noted that Davies is quoted from an interview for the World Science Festival in 2014. Since then, we have seen progress towards Davies's vision of a more multidisciplinary approach to SETI. Specifically, we have seen NASA return to the technosignature search in 2018 with a list of potential targets that have expanded beyond radio signals. For example, one technosignature type gaining popularity among scientists is evidence of industrial activity modifying exo-planet atmospheres. In addition, with the launch of the James Webb telescope at the end of 2021, there is now the technology to better analyse atmospheric composition even at vast distances.
Looking at planetary surfaces is undoubtedly an eminently sensible addition to SETI efforts. However, might we want to turn our attention a little closer to home?
In the opening quote from the previously mentioned World Science Festival interview, Professor Davies suggests a few possible examples of technosignatures targets. One of these hypothetical targets is any asteroids chopped up in a distinctive way that might be orbiting our solar system. While many rocks are orbiting our sun, there is one that has already produced some tantalising indications of possible deliberate modification. I am referring here to the dwarf planet Ceres.
Ceres is the largest object in the central asteroid belt, with a diameter of 590 miles (950 km). At its closest to earth, this barren rock passes about 1.5 astronomical units from our world (1 AU is the distance between the earth and the sun). Ceres orbits the sun at a distance from the sun, which the Titius–Bode law predicts is where we should find another planetary system, just between Mars and Jupiter. This prediction has led astronomers to theorise that a planet nicknamed Phaeton once existed here but was somehow disrupted, giving rise to the asteroid belt and Ceres.
Our first good look at Ceres came in 2015 as NASA's Dawn spacecraft entered orbit, having previously rendezvoused with Vesta, the second-largest object in the asteroid belt. For all but enthusiasts of asteroid research, Vesta was nothing more than a big potato-shaped rock pot marked with craters. Ceres, however, offered far more mysteries and several intriguing features.
While the surface composition is the same as that of C-type asteroids, there is growing evidence the rocky surface hides a significant amount of water. Possibly ongoing sub-surface geological activity is also present. While water is an exciting discovery, considered essential for life, it's not the presence of this crucial liquid that has brought the attention of space scientists towards this barren world.
Images of one of the most significant impact structures on Ceres, the Occator crater, included several mysterious bright spots. The data analysis from NASA's Dawn probe enabled a detailed study of surface features, including the bright spots. While the exact explanation remains open to question, a leading hypothesis is the presence of highly reflective salts resulting from the action of ice volcanoes. These so-called cryovolcanoes would be produced by sub-surface brine reservoirs pushed upwards by hydrothermal processes. However, it must be said that there are professional doubts about the cryovolcanic activity on Ceres as no energy source sufficient to explain their presence has been confirmed.
Images showing a shining beacon of light within the Occator crater whilst in complete shadow would suggest more than simple reflectivity.
Another striking feature is inside the 92km diameter, 3km deep impact structure as it transpires. In the middle of the Occator region is a luminous region, Cerealia Facula, with a central dome 3km wide by 340m high named Cerealia Tholus. To the east is a cluster of more minor luminous spots, Vinalia Faculae, one of which incorporates an intriguing geometric pattern.
As part of research conducted by a University of Cadiz team, an experimental artificial neural network was taught to recognise shapes and patterns. The initial intention of the study was to compare how human beings and machines recognise planetary images. In doing so, they could better understand whether specially designed artificial intelligence can help astronomers discover physical evidence of extraterrestrial intelligence.
The neural network was given images of Ceres and soon identified a circle within a square enclosed by a larger triangle. These geometric structures, reminiscent of alchemical symbols, were initially occluded by the bright glow emanating from the reflective region in which they are situated. The same peculiar feature was also picked out by human volunteers forming a control group, all of whom had no training in astronomy. The joint human-AI confirmation seemed to support further the legitimacy of purportedly identifying an anomaly.
The experiment was carried out by the same Spanish neuropsychologist, Gabriel G. De la Torre, who was associated with work on the cosmic gorilla effect that we previously encountered. The results led many scientists to question how we might apply artificial intelligence in the search for extraterrestrial intelligence (SETI). In addition, questions arose as to whether AI designed to assist space science might carry elements of human perceptual bias, a type of digital pareidolia. If so, it might inadvertently fool us into believing we had found evidence of aliens.
"We weren't alone in this; some people seemed to discern a square shape in Vinalia Faculae, so we saw it as an opportunity to confront human intelligence with artificial intelligence in a cognitive task of visual perception, not just a routine task, but a challenging one with implications bearing on the search for extraterrestrial life (SETI), no longer based solely on radio waves," explains Gabriel G. De la Torre.
The University of Cadiz scientists, having already recognised the potential for undetected technosignatures associated with the cosmic gorilla effect, brought together 163 volunteers with no training in astronomy to test their perceptions of the Occator crater site. The researchers then did the same with an artificial vision system (based on convolutional neural networks), trained to recognise shapes depicted in thousands of images. The full results are available in the associated paper, Does artificial intelligence dream of non-terrestrial techno-signatures?
"Both people and artificial intelligence detected a square structure in the images, but the AI also identified a triangle," notes De la Torre, "and when the triangular option was shown to humans, the percentage of persons claiming to see it also increased significantly."
The square seemed to sit centrally positioned within the triangle, and inside its boundaries, there even appeared to be a faded circle.
"On the one hand, despite being fashionable and having a multitude of applications, artificial intelligence could confuse us and tell us that it has detected impossible or false things," says De la Torre, "and this, therefore, compromises its usefulness in tasks such as the search for extraterrestrial technosignatures in some cases. We must be careful with its implementation and use in SETI."
He continued, "On the other hand," he adds, "if AI identifies something our mind cannot understand or accept, could it in the future go beyond our level of consciousness and open doors to reality for which we are not prepared? What if the square and triangle of Vinalia Faculae in Ceres were artificial structures?"
We must recognise that any artificial intelligence created by human beings will likely include some of our limitations and biases. Therefore, caution is warranted in the AI application process. Consider De la Torre's final 'what if' question more closely. What if the apparent square, triangle, and circle within Ceres' luminous Vinalia Faculae region really are artificial elements?
Might we be looking at an instance where aliens have "chopped up an asteroid in a very distinctive way", one of the potential technosignatures suggested by Professor Paul Davies?
In a recent collaborative study addressing issues relating to the Fermi Paradox, four highly respected space scientists, Jonathan Carroll-Nellenback, Adam Frank, Jason Wright and Caleb Scharf, modelled the settlement of the galaxy by space-faring civilisations. Their paper, The Fermi Paradox and the Aurora Effect: Exo-civilization Settlement, Expansion, and Steady States, discusses the possibility that extraterrestrial civilisations may expand across the galaxy in wave fronts that take advantage of the movement of stars relative to each other.
The benefit of waiting for star systems to move closer is that it requires less effort to colonise their associated planets. Any advanced civilisations may expand rapidly through the galaxy by taking advantage of stellar motion, never having to travel enormously vast distances in space. The researchers speculate that our own Sol system may have been previously visited but now is perhaps located at an unfavourable distance for exploration. An expanding civilisation may be now waiting for us to come to them, so to speak.
In fact, we know that 70,000 years ago, a star passed right through the Oort cloud out on the edges of our solar system, and there would have been many other such close passes during the last few billion years. Perhaps during one such fly-by, visitors from a passing star explored our solar system, colonised worlds, and exploited resources through "large-scale quarrying". Statistically speaking, it is reasonable to speculate that extraterrestrial intelligence could have visited our part of space sometime in the last 4.5 billion years.
Suppose the luminous regions and geometric patterns are indeed the work of ancient aliens. Might they not be simply remnants of mining? Could the features on Ceres be a deliberate message left for future visitors? After all, math and geometry have long been considered universal languages. How would the ancient creators ensure any other civilisation that arrived would eventually locate their message? What about engraving the enormous geometric structure into the middle of a naturally highly reflective region – or deliberately surfacing the surrounding area with such materials?
To add to the mystery, Dr De la Torre has now identified other strangeness regarding geological features on Ceres. Ahuna Mons is a 4 km high mound with a reflective surface, suggested as also being of possible cryovolcanic origin. Situated beside Ahuna Mons is a crater with similar aspects such as diameter, age and morphology. This strange pairing raises the possibility of artificial engineering of the landscape. Here I will quote directly from his paper Evaluation of Several Computer Vision Feature Detectors/Extractors on Ahuna Mons Region in Ceres and Its Implications for Technosignatures Search:
"According to our results and independently of the possible cryovolcanic or cognitive bias (either human- or AI-based) hypotheses, in the future, we have to be prepared for the possibility of a new form of technosignature, a natural-like object/phenomena where natural patterns are artificially or intelligently designed to be mostly indistinguishable from nature. We may need AI's eyes and multidisciplinary teams to perceive, identify and understand them, whether they are star-like megastructures (Dyson spheres) [46] or mountains."'
I find that the entire luminous Vinalia Faculae region of the Occator crater resembles a star map. Of course, it could be my brain seeking patterns in random features, a problem we have already highlighted. However, might some long distant civilisations have left us a map of their home system, marking the vital home world location with a geometric symbol?
If we look out into the darkness and see intriguing things that might indicate intelligence, will we always seek to airbrush them out, accepting mundane explanations? Will we always promptly turn away and look for something else, just a little more extraordinary?
There may be no such thing as unambiguous evidence of alien intelligence. Whether in radio signals, derelict probes, genetic engineering, or distant megastructures, we might always be able to explain away signatures of alien technology rationally. We might always see them as the most similar known phenomena. It is conceivable that we will always be able to offer a natural hypothesis for potentially artificial phenomena. Forever favouring natural solutions where there is merit for artificiality. Just as advanced alien technologies may be unrecognisable to us as technology, we may not recognise their effects on planetary environments.
"What would happen if a caveman saw a cellphone?" Asks Harvard astronomer Avi Loeb. "He's seen rocks all his life, and he would have thought it was just a shiny rock."
Part 3 - Part 5
Sources
Does artificial intelligence dream of non-terrestrial techno-signatures?
The cosmic gorilla effect or the problem of undetected non terrestrial intelligent signals
The Fermi Paradox and the Aurora Effect: Exo-civilization Settlement, Expansion, and Steady States
Meet Paul Davies, The Man Who’ll Greet the Aliens