Suppose aliens exist and imagine that some of them have been observing our world for four and a half billion years. What the hell would they have seen? For much of that vast time period, the appearance of the Earth changed slowly and steadily. Continents drifted; ice cover waxed and waned; successive organisms appeared, transformed, and many of them became extinct.
But in a tiny sliver of Earth’s history—the last hundred centuries—the patterns of plants have changed even faster than before. This marked the beginning of agriculture—and later of urbanisation. Changes intensified as the population of humans grew.
Then the improvements came even quicker. Within a century, the volume of carbon dioxide in the atmosphere started to increase dangerously quickly. Radio pollution that could not be explained by natural processes have arisen and something else has occurred without precedent: rocks launched from the surface of the earth have completely escaped the biosphere. Some spacecraft were launched into orbits around the Earth; others were on their way to the Moon, Mars, Jupiter, and even Pluto.
If those hypothetical aliens kept watch, what will they be seeing in the next century? Would the last spasm of action be accompanied by silence due to climate change? Or is the ecosystem of the earth going to stabilise? Is there going to be major terraforming? Can the spaceship armada launched from Earth spawn new oases of life elsewhere?
Let us think specifically about the future of space exploration. Successful missions such as Viking, Cassini, New Horizons, Juno, and Rosetta have all been accomplished with technology from the last century. We can reasonably conclude that during this century, the entire solar system—planets, moons, and asteroids—will be explored by robotic craft flotillas.
Will there still be a human part in the crewed spacecraft?
There is no denying that NASA’s latest Perseverance rover racing across the Jezero crater on Mars could miss some surprising discoveries that no human geologist could possibly have overlooked. But machine learning is moving quickly, just like sensor technology. On the other hand, the cost difference between the crewed and the autonomous missions remains enormous.
We believe that the future of crewed spaceflight rests with privately-funded explorers such as SpaceX and Blue Origin, who are prepared to engage in a much more risky price-cutting scheme than Western nations might enforce on publicly financed projects. These ventures—bringing Silicon Valley-type culture to a domain long dominated by NASA and a few aerospace conglomerates—have innovated and improved rocketry far faster than NASA or the European Space Agency. The potential position of national agencies will be attenuated—becoming more like an airport than an airline.
We are close to the end of Darwinian evolution, but the technological evolution of intelligent beings is just starting.
We would argue that inspiringly run private companies should face all human-involved missions as low-priced high-risk projects. There will still be a lot of volunteers—a few maybe even accepting one-way tickets—driven by the same reasons as early explorers and mountaineers. The word ‘space tourism’ should be avoided. It encourages people to believe that such projects are normal and low-risk. If this is the perception, the unavoidable accidents would be as horrific as those of the space shuttle. These exploits must be marketed as hazardous, extreme sports, or intrepid exploration.
The most important obstacle to space travel is the inherent inefficiency of the chemical fuel and the need to bear a fuel weight well beyond that of the payload. As long as we are relying on chemical fuels, interplanetary travel will remain a challenge. Nuclear power may have been revolutionary. Allowing even higher in-course speeds will greatly reduce transit times in the solar system, minimising not only the boredom of astronauts but their exposure to harmful radiation. It is more effective if the fuel supply can be on the ground; for example, by propelling spacecraft into orbit through a “space elevator”—and then by using a “star-shot”-type laser beam produced on Earth to push a “sail” attached to the spacecraft.
By 2100, the thrill-seekers in the mould of Felix Baumgartner (the Austrian skydiver who broke the sound barrier in the free fall of a high-altitude balloon in 2012) may have developed bases on Mars, or maybe even on asteroids. Elon Musk said he wants to die on Mars—”but not on impact.” It’s a practical target, and it’s an attractive one for some.
But don’t expect a mass exodus from Earth. It’s a dangerous illusion to believe that space provides an escape from Earth’s problems. We’re going to have to solve those here. Addressing climate change or the COVID-19 pandemic may sound overwhelming, but it’s a piece of cake compared to terraforming Mars. There is no spot in our solar system that provides an atmosphere as clement as the Antarctic or the peak of Mount Everest. Simply put, there is no Planet B for ordinary risk-averse people.
Even, we (and our offspring here on Earth) should cheer on the courageous space explorers. They have a pivotal role to play in shaping the post-human future and deciding what is going on in the 22nd century and beyond.
Pioneer explorers will be ill-adapted to their new habitat, so they will have a compelling reason to redesign themselves. They will harness the super-powerful genetic and cyborg technologies that will be created in the coming decades. This may be the first step towards a new species divergence.
Organic organisms need a planetary surface ecosystem in which life will emerge and evolve. But if post-humans make the leap to completely inorganic intelligence, they’re not going to require an environment. They may also prefer zero-gravity, particularly in the construction of massive objects. It is in deep space where non-biological brains will grow forces that humans can’t even imagine.
There are chemical and metabolic constraints on the scale and processing capacity of organic brains. We might already be close to these thresholds. However, such limits do not extend to or constrain electronic computers (still less, perhaps, quantum computers). Thus, by any concept of “thinking,” the volume and speed that can be accomplished by organic human-type brains would be swamped by AI cerebrations.
We may be at the end of Darwin’s evolution, but the technological evolution of intelligent beings is just beginning. It could happen the fastest away from Earth—we wouldn’t expect (and definitely wouldn’t want) such dramatic changes in humanity here on Earth, while our survival may rely on ensuring that the AI on Earth remains “benevolent.”
Few doubt robots will eventually exceed or improve more and more of our distinctly human capabilities. Disagreements are just about the timescale for this to happen. Inventor and futurist Ray Kurzweil claims it’s only going to be a matter of decades. More careful scientists are looking forward to decades. Either way, the timescales for technological advancements are an instant relative to the timescales of Darwinian evolution that contributed to the creation of humanity—and, more importantly, less than a millionth of the vast expanses of cosmic time ahead. The results of future technological evolution could exceed humans by as much as we surpassed the slime mould.
But, you would ask, what about consciousness?
Philosophers and computer scientists are discussing whether consciousness is something that only characterises the kind of wet, organic brains possessed by humans, monkeys, and dogs. Would electronic intelligence, even if their intellects seemed superhuman, lack self-awareness? The ability to imagine things that don’t exist? An inner life, huh? Or is consciousness an emerging property that any sufficiently complex network will eventually have? Some claim it’s meaningless and semantic, like asking whether the submarines can swim.
Extraterrestrial culture may be made up of a swarm of microscopic probes that could have escaped detection.
We don’t think that’s it. If the robots are what computer scientists refer to as “zombies,” we would not have given their experience the same importance as ours, and the post-human world would seem very grim. On the other side, if they are conscious, we can accept the possibility of their potential hegemony.
What would be their driving motivation if they become completely autonomous entities? We have to confess that we have absolutely no idea. Think of the variety of bizarre motives (ideological, financial, political, egotistical, and religious) that have driven human efforts in the past. Here’s a simple example of how different they could be from our naive expectations: They may be contemplative. Far less obtrusively, they may know that it is easier to think at low temperatures, while moving away from any star, or even hibernating for billions of years before the cosmic microwave background cooled well below its current 3 degrees Kelvin. At the other end of the spectrum, they could be expansionist, which seems to be the expectation of most of those who thought about the future trajectory of civilizations.
And if life existed only on Earth, it does not need to remain a negligible, insignificant function of the universe. Humans could jump-start a diaspora in which ever-more-complex knowledge spreads throughout the galaxy, transcending our limitations. The “sphere of control” (or some would envisage a “frontier of conquest”) might cover the entire galaxy, spread through self-reproducing machines, transmit DNA or instructions for 3-D printers. The leap to the nearby stars is just an early step in this process. Interstellar travel—or even intergalactic travel—would hold no fear to near-immortals.
Moreover, even though the only propellers used were currently understood, this galactic colonisation would take less time than the more than 500 million years after the Cambrian eruption. And even less than the 55 million years since the advent of primates, if it proceeds in a relativistic way.
Expansionist possibilities would have the effect that our descendants would become so visible that every alien race would become aware of them.
The key question remains: are there any expansionists whose domain might have an effect on ours?
We don’t know that. The emergence of intelligence may require such a rare chain of events and occurrences—like winning a lottery—that nothing else has happened. This will disappoint SETI searchers and explain the so-called Fermi Paradox—the surprise expressed by physicist Enrico Fermi over the lack of any sign of the existence of other intelligent civilizations in the Milky Way. But presume we’re not alone, though. What kind of proof would we like to find?
Suppose there are also several other planets where life has evolved, and that on some of them, Darwinian evolution has taken a path close to that on Earth. Even then, it is extremely unlikely that the main stages will be coordinated. If the advent of knowledge and technology on a planet lags far behind what has happened on Earth (because, for example, the planet is younger, or because certain evolutionary bottlenecks have taken longer to negotiate) then that planet would have revealed no signs of ET. Earth itself would possibly not have been observed as a life-bearing planet in the first two billion years of its existence.
But life may have had a head start of a billion years or more around a star older than the sun. Notice that the present age of the solar system is around half the age of our galaxy and half the total life expected by the sun. We expect a large fraction of the stars in our galaxy to be older than the sun.
The history of human technological culture has been calculated in a few millennia. It could be only a few more generations before humans are overtaken or transcended by inorganic intelligence, which will then continue to grow over billions of years through a faster-than-Darwinian timescale. Organic human-level intelligence could, in general, be only a brief interlude before machines took over, so if alien intelligence had developed in the same way, it would most likely be caught in a brief period of time where it was still represented in that form. If we were to detect ET, it would be much more likely to be electronic where dominant beings are not flesh and blood—and might not even be bound to a planetary surface.
Astronomical discoveries have now demystified many of the likelihood variables in the so-called Drake Equation—a probabilistic effort historically used to estimate the number of advanced civilizations in the Milky Way. The number of potentially habitable planets has changed from being totally unknown just a few decades ago to being directly determined by observations. At the same time, we need to reinterpret one of the main factors in the Drake equation. At most, the life of an organic civilization can be millennia. But the electronic diaspora may have continued for billions of years.
It is in deep space where non-biological brains will grow forces that humans can’t even imagine.
If SETI were successful, it would be unlikely that the signal would be a decodable message. It will most likely expose a by-product (or maybe even a malfunction) of some super-complex system beyond our comprehension.
The practice of referring to “alien civilisations” can in itself be too limiting. Civilization is a culture of individuals. ET, on the other hand, maybe a single integrated intelligence. Even if messages are sent, we do not identify them as artificial because we do not know how to decipher them, in the same way that a veteran radio engineer with only amplitude-modulation (AM) transmission may have a hard time decoding modern wireless communications. In reality, compression techniques strive to make the signal as close to noise as possible; in so far as the signal is predictable, there is space for further compression.
So far, SETI has concentrated on the radio portion of the spectrum. But we can investigate all wavebands, including the optical and X-ray bands. We should also be alert to other signs of non-natural phenomenon or behaviour. What might be a pretty generic signature, then? Energy consumption, one of the possible hallmarks of advanced civilization, seems difficult to hide.
Starlight is one of the most plausible long-term energy sources open to advanced technology. Powerful alien civilizations may create a mega-structure known as the “Dyson Sphere” to gather stellar energy from one star, several stars, or even the entire galaxy.
The other possible long-term energy source is the regulated fusion of hydrogen into the heavier nucleus. In both cases, waste heat and a visible mid-infrared signature would have been an expected outcome. Or, one might seek proof of large objects such as the Dyson Sphere itself. Intriguingly, it is worth searching for objects in our own solar system: We might be able to rule out visits by human-scale aliens, but if an extraterrestrial culture had mastered nanotechnology and passed its intellect to computers, the “invasion” maybe a swarm of microscopic probes that may have escaped detection. Yet, it would be easier to transmit a radio or laser signal than to pass through the mind-boggling distances of interstellar space.
Finally, let’s move on quickly, not only for a few millennia but for an enormous timescale, millions of times longer. As interstellar gas is to be absorbed, the ecology of stellar births and deaths in our galaxy will continue more steadily, before the environmental shock of a collision with the Andromeda galaxy comes to an estimated 4.5 billion years. The debris of our galaxy, Andromeda, and their smaller companions (known as the Local Group) will be aggregated into one amorphous (or perhaps elliptical) galaxy.
As the interstellar expansion accelerates, distant galaxies will travel farther forward, receding faster and faster until they disappear—rather like objects dropping through a black hole—with a horizon beyond which they are lost from sight and causal interaction. But the remains of our Local Group will survive for a much longer period. Long enough, perhaps, for what has been called the “Kardashev Type III” hypothesis, in which a civilisation uses energy from one or more galaxies, and perhaps even from supermassive black holes, to arise as the result of a long-term tendency for living systems to achieve complexity and negative entropy (a higher degree of order).
The only limits set by fundamental physics will be the number of accessible protons (because they can, in theory, be transmuted into any element) and the total amount of available energy (E=mc2, where m is mass and c is the speed of light) which can be transformed from one form to another.
Essentially, all atoms that were once in stars and gas could be converted into structures as complex as a living organism or silicone chips except on a galactic scale. A few science fiction writers envisage stellar-scale engineering to build black holes and wormholes—concepts well beyond any technical capability that we can imagine, though not in violation of simple physical rules.
If we want to go to other extremes, the total mass-energy content of the Local Group is not the maximum of the available resources. It would also be consistent with the physical laws of an unbelievably advanced society with the galaxies that are receding due to the cosmic expansion of space before they accelerate and disappear over the horizon. Such a hyper-intelligent species might pull them in to create a section resembling Einstein’s original idea of a static universe in balance, with a mean density such that the cosmic repulsion induced by dark energy is precisely balanced by gravity.
All we’ve said is consistent with the laws of physics and the cosmological model that we understand. Our speculations presume that the repulsive force causing cosmic acceleration persists (and is defined as the dark energy or the cosmological constant of Einstein). But we should be open-minded about the possibility that we don’t understand a lot of things.
Human brains have changed very little since our ancestors roamed the African savannah and faced the obstacles that life then posed. It is certainly amazing that these brains have helped us to make sense of the quantum subatomic universe and the cosmos at large—far removed from the common sense, the daily world in which we have evolved.
Scientific borders are moving quickly. But at some stage, we could reach the buffers. There may be phenomena, some of which may be vital to our long-term destiny, that we know little more than a gorilla understands the origin of stars and galaxies. Physical reality may include complexities that neither our intellect nor our senses can comprehend. Electronic brains can have a different understanding of reality. As a result, we cannot predict or even consider the motivations of such brains. We cannot determine whether the Fermi paradox means their absence or merely their choice.
Conjects of advanced or intelligent alien life are shakier than those of simple life. However, there are three features that may define entities that SETI searches may have revealed.
• Intelligent life is not likely to be organic or biological.
• It will not live on the surface of the earth where it’s biological precursor has arisen and evolved.
• We would not be able to understand the purposes of such life forms.
Two familiar maxims should apply to all SETI searches. On the one hand, ‘the lack of evidence is not proof of absence,’ but, on the other, ‘extraordinary statements require extraordinary proof.
Note – Some say that humanity is not ready to witness the truth that life in the universe exists. Not only exists but is already an inhabitant of our planet. There is the possibility of mass hysteria, but I feel this will come from religious sources and older generations who have already been brainwashed o conceive the idea that aliens don’t exist. History doesn’t lie, and with all the scientific evidence we have collected through the decades, and with Tesla stating he was in contact with extraterrestrials. And all the hype surrounding his technology and death plus many more evidence coming to light. It’s about time that humanity takes the next step forward and embrace the fact that aliens exist.