Centauri Dreams

Is it possible that we can account for the Fermi paradox by looking to our own behavior as a species? Some science fiction of the 1950s pointed in that direction, as witness The Day the Earth Stood Still (1951). Dr Kelvin F Long addresses the question in terms of the ‘zoo hypothesis’ in the essay below, asking what our culture could do to make itself less threatening to any outsider. Long is an aerospace engineer, astrophysicist and author. He leads the Interstellar Research Centre, a division of Stellar Engines, which conducts research on the science and technology associated with deep space exploration. He is a Chartered Member of the Institute of Physics and a Fellow of the British Interplanetary Society. He tells me he wrote this article as a means of fundamental protest at the current conflicts engulfing humanity and as a plea to any observing ETI not to judge our species by the immorality of those who hold power over the potential of humankind. Also available on his site are two other documents pertaining to this topic: The Second Sun and Open Letter to the Permanent Members of the UN Security Council.

by Kelvin F. Long

As humanity reaches further out into the Cosmos through our long-range astronomical instruments and also robotic probes, our presence is sure to be noticed by any hypothetical extraterrestrial intelligence (ETI) that may also exist. Yet the development of our technology is not without complications given the potential dual use. Since it involves large powers and energies, this especially includes that any space propulsion machine can also be turned into a weapon. If ETI does exist then they will surely be mindful of how we use this technology and attempt to gauge whether we will bring peace and prosperity to any life in the Universe, or modes of destruction. Given this scenario, it is reasonable to consider that any civilisation that reaches a certain level will reach a point where they will be either permitted to continue in their advance outwards, or potentially face stagnation by clandestine means. It is argued that since within decades we are likely nearing this point of paradigm shift in space technology, the monitoring of our civilisation should be expected currently. In the near future we should prepare for the eventuality that we will either be greeted by intelligence from another world or forced to be restricted within a permanent zoo that constrains us to the Solar System. Preparing for this, such as through reforms of institutions like the United Nations, should be a key component of our nation state relationships through a moral and legitimate multilateral approach to problem solving, but also our exploration roadmaps.

Keywords: Extraterrestrial Contact, United Nations

Introduction

Life on planet Earth has taken many millions of years to evolve to the complex life-forms that characterise Homo sapiens with all its intelligence and associated technological tools. Yet, for centuries, astronomers have speculated [1] that it may be possible that intelligent life exists elsewhere, and this search has informed some of the motivations for our national space programs [2]. Life may have evolved from the same primordial soup and simply been transmitted from one world to another, such as during planetary collisions during the early stages of the Solar System formation, or it may have separate points of evolution that are independent from each other. A discovery of life representative of a separate biogenesis from Earth [3] would be one of the most profound moments in the history of the scientific endeavour.

This search has become more poignant in recent years since the discovery of thousands of exoplanets around other stars thanks to amazing astronomical observatories like the Hubble Space Telescope, the Kepler Space Telescope and the James Webb Space Telescope. These observatories and others that succeed them are sure to change our perspectives on models of planets, stars and life in the Universe as their sensitivity and resolution improves with each decade of technological development. In our search for planets around other stars we have discovered Hot Jupiter’s, Super Earth’s, tidally locked planets and they range in compositions from mostly iron to mostly water [4]. It seems only a matter of time where instruments like this will be able to directly image exoplanets around other stars and fully characterise their atmospheric composition and possible evidence of technological industrialisation.

In a recent article published in Nature Astronomy, Crawford and Schulze-Makuch [5] has argued that it is likely that the apparent absence of Extraterrestrial Intelligence (ETI) in our solar system might be explained by a form of zoo hypothesis [6] in action around the emerging human civilisation. They argue it is either that, or we are the only intelligence that exists in the galaxy, and possibly in the Universe. This would be unsatisfactory since it would imply a special observer position for planet Earth in contradiction to a Copernican principle of cosmology.

Fundamental to the arguments regarding life visiting our solar system is the Fermi paradox, which asserts that there is a contradiction between our theoretical expectations for intelligent life emerging in the Universe and our apparent lack of observations to confirm it has indeed done so. The calculation for such a prediction is based on the number of galaxies, stars, and planets, their measured ages and spectral types when compared to the solar system from which we originate. From a statistical basis, a calculation of probability suggests that we are not special but perhaps typical of an average system that might evolve.

Even if a zoo containment policy was not in action by ETI around our solar system, assuming they exist, they would be wise to at least monitor our activity. In the future it is possible that we will send a robotic probe towards the planets of another star. Since the average distance between stars is 5 light years, any flyby probe crossing this distance in less than a century, would have a velocity of order 0.05c or 15,000 km/s which would have significant kinetic energy associated with its motion.

The Trinity nuclear test in July 1945 had an associated yield of 25 kilotons TNT equivalent, or around 100 TJ. An object with this energy travelling at a speed of 0.05c would only have to have a mass of around ~1 kg. A much larger mass, let’s say of order 1 ton, for the same velocity would have an associated energy of 112,300 TJ or approximately 26,900 ktons TNT equivalent which is around 1,100 Trinity events. Therefore, any probes sent from our solar system towards a potential habitable exoplanet would be of grave concern to any observing ETI. If a probe is able to be decelerated into orbital velocity this may put at rest some concerns and reassure its scientific nature, but before any deceleration takes place the probe would first travel the majority of the distance at the determined cruise velocity and therefore still require careful scrutiny of its intention and trajectory.

Reversing roles, if we detected an emerging species from a nearby star system that also appeared to be technological, in terms of them maturing to an advanced space capability we might also wish to characterise the threat level. Borrowing ideas from how such threats are categorised by nation states we might determine as: Green: Low threat, intention appears to be benign; Amber: Moderate, intention appears benign but advise caution subject to more data; Red: High threat, actions by ETI indicate a threat to humanity is likely. Indeed, we were potentially treated to such an opportunity in 2017 with the arrival of the interstellar asteroid ‘Omuamua, the nature of which remains controversial today [7].

An analogy for ETI observing humanity’s technological developments is the allied monitoring of German nuclear experiments during World War II. Particularly after 1938 when Otto Hahn first discovered nuclear fission and the creation of the ‘Uranium club’ to investigate the military benefits of a nuclear chain reaction. This effort by Germany prompted the creation of the Manhattan project in the United States, to construct the world’s first atomic bomb. Clearly Germany was seen as a significant global threat at the time.

The problem with any such categories is that threats come in many forms and can be intentional or unintentional. In addition, it is difficult to assess the impact on the development of a society by simply exposing them to a simple piece of knowledge or a technology. This has been well recognised by our own society since at least the 1960s with the publication of the Brookings Institution report which stated: “Certain potential products or consequences of space activities imply such a degree of change in world conditions that it would be unprofitable within the purview of this report to propose research on them. Examples include a controlled thermonuclear fusion rocket power source and face to face meetings with extraterrestrials” [8].

Imagine for example, if we went back in time and communicated to Stone Age people that stars were other suns. That innocent piece of information may have profound implications on social-cultural development and give rise to new philosophies. Alternatively, imagine if we gave them an item as innocent as a single wood nail. What inspiration and technological spin-offs would that promote now that they had been exposed to the broader possibilities?

In his famous physics lecture serious the physicist Richard Feynman imagined that there was a cataclysm and all scientific knowledge was lost or destroyed and he asked what one sentence would you want to be passed onto the next generation so that they could build up science and civilisation again. He opinioned that it was the “atomic fact, that all things are made of atoms…In that one sentence, you will see, there is an enormous amount of information about the world, if just a little imagination and thinking are applied” [9].

Now imagine that if ETI was to come here in a spacecraft propelled by technology which, to quote Arthur C Clarke, appeared to be “indistinguishable from magic” [10] to our eyes, since it was based on principles of physics we were yet to discover. It’s possible they would share that technology with us, but even if they didn’t, we might attempt to steal it. Alternatively, even if they refuse to discuss it, now that we have seen it, it will promote research programs in our society that one day leads to its maturation. In other words, the mere seeing of a new phenomenon is enough to spark interest from a curious species that may lead to its eventual creation here. A few years ago, this idea was suggested as a physics postulate by this author where “No information can be contained in any system indefinitely” [11].

In the television series Star Trek they codified these sentiments into an effective Prime Directive [12]. For this reason, any ETI would be concerned about contaminating our species with knowledge or technology and this would be a prudent reason to keep at a distance. Yet also, if they decide we have hostile tendencies as a part of our nature, they would be mindful not to give us any advantage scientifically which could accelerate our development and so increase the potential threat to them.

In general, it would be prudent to speculate when might ETI be most concerned about a human presence in space and therefore warrant actions to mitigate our excess and reach? Since our progress in space is primarily driven by our technological capacity, our advance with science and engineering machines would be of primary importance and at some point, we would reach a peak of maximum interest and therefore a decision point upon which to take actions over our continued activities in space. This is arguably becoming more important since our technological level is rapidly approaching the point where interstellar missions may become possible in future generations since the science case for making the journey is compelling [13].

Indeed, this author has previously estimated that if there are any ETI civilizations within 200 light years distance then first contact may potentially occur any time in the next 100 – 200 years [14]. This is on the basis that technology advances at a certain pace of generations with increasing levels of performance, to eventually maturate to the required level to achieve a given mission over a set distance at a minimum cruise speed. For example, a mission to the nearest star Proxima Centauri at 4.3 light years in 100 years trip time would require a cruise speed of 0.05c, which is a factor ~150 times what we could do in space today with our most advanced propulsion technology, which suggests at least two orders of magnitude improvement required in our current technological state of art before the interstellar mission becomes feasible.

Detecting Emissions

The evidence to support or refute any solutions to the Fermi Paradox by long-range observations depend on our ability to detect emissions from deep space that might demonstrate technology use, such as through deliberate communication transmissions or on accidental release of power and propulsion signatures that might indicate an ETI presence. The detection of emission signatures from space as potential evidence for ETI has been discussed extensively by the astronomer Carl Sagan [15].

Historically all efforts towards the Search for Extraterrestrial Intelligence (SETI) have been focussed on the detection of transmitted radio communications. One of the factors that has influenced this program is the previously believed position that messaging through radio waves (or lasers) is cheaper when compared to sending reconnaissance probes [16], but this is no longer necessarily the case thanks to innovative programs like the Breakthrough Initiatives Project Starshot [17].

In recent years however the perspective on messaging is changing and there is an increased emphasis of technosignatures [18]. This is especially important since the power spectrum emissions of any propulsion technology would likely be several orders of magnitude higher than any transmitted communication signals through radio waves [19].

Since astronomers rely on the detection of natural astrophysical emissions to inform their physical models, it follows that any artificial emissions would also be detected by those same astronomers, so that they could be analysed for either their natural or artificial nature. Therefore, to contain human civilization, to include our awareness of an ETI presence in the galaxy, any artificial emissions coming towards our solar system would have to be filtered by them before arriving at our detectors.

Any filtering would also have to span an enormous range. Diffuse hard x-ray emission from the gas giant Jupiter has been measured at 3.3×10¹⁵ erg/s [20]. A recently discovered supergiant x-ray transient XTE J1739-302 was measured with a luminosity or radiated power of 10³⁶ erg/s [21]. A typical supernova at its maximum brightness might have a luminosity exceeding 10⁴³ erg/s, which is a billion times that of the Sun in our own solar system. A Black Hole binary reached a peak gravitational wave luminosity of 3.6×10⁵⁶ erg/s [22].

The power spectrum from an advanced propulsion fusion engine might be characterised by around 10²² erg/s which would correspond to around 10¹⁵ W propulsion jet power, appropriate for a vehicle motion in the range 0.1-0.15c [23]. There are in fact a range of ideas for space propulsion that have been proposed in the literature, from sails to beamers [24], fusion [25] to antimatter [26], relativistic ramjets [27] to space-drives [28], Unruh radiation drives [29] and other methods [30, 31]. To make significant progress, research is required on all of the physics and engineering concepts derived by human imagination and then appropriate links to physics effects in order to estimate the range of emission properties. This includes going beyond known physics and even into the speculative fields of space-time drives or warp drive [32] and wormholes [33], using the tools of General Relativity theory.

How do we distinguish in our models between the discovery of a new astrophysical object and the spectrum from an artificial source such as a power and propulsion technology indicative of industrialisation by ETI? Our interpretation of any data depends strongly on the accuracy of our scientific models to describe physical phenomena in astrophysics but also the physics and engineering of advanced spacecraft machines and how they operate [34].

If a zoo containment policy of our solar system and humanity were in place by ETI, then this raises the question of how this would be practically policed, and a basic analysis of the requirements suggest that it would in fact appear to be rather impractical. Indeed, if we imagine a containment zone around our solar system that was a hollow sphere of radius 100 Astronomical Units, this will have a shell volume of ~2.81×10²⁹ m³.

If we then assumed that any artificial megastructure that made up this filtering material was only 100 m in thickness and assumed a light but smart microporous and transparent optically thin material, perhaps similar to silica aerogel, with an average density of 20 kg/m³, which can survive in space environments whilst maintaining its strength. This then would require a perimeter shell mass of around ~5.62×10³⁰ kg which is approximately ~3 times the mass of our own sun. It would also be noticed gravitationally since it would influence the planetary orbits, and it would need an ability to self-adjust its position to prevent drift.

The use of any material density beyond the one assumed here, such as for metals, would significantly increase the megastructure mass of such a perimeter. If such a material was acting as an emissions filter, the internal matrix of the substance would have to be designed in some way to block out artificial signatures but permit the transmissibility of natural signatures from astrophysical sources to not alert us to the strategy in operation.

In addition, since the presence of our civilization is continually increasing through our robotic probes, the diameter of the wall must be enlarged periodically or altered in some way which may require in-situ management. But then if it is allowed to expand what would be the limit of the containment policy? The barrier would also have to be dynamically operable to allow the passage of long-period comets on eccentric orbits or interstellar objects like ‘Oumuamua [35] and 2I/Borisov [36] to get through and enter our solar system. Instead, perhaps their arrival itself represents evidence that falsifies a containment barrier?

The shell would also have to have a temperature less than the 2.72 K cosmic background microwave radiation, and probably close to 0 K, to prevent its detection through thermal imagers, and so that it did not absorb any energy from its surroundings due to its high transparency. Since it surrounds a star, there is a risk of it trapping the energy from that star in a manner similar to a Dyson sphere, and so any energy passing through it from the star could not undergo attenuation and must be fully transmissible. We might refer to this as a Kelvin shell due to its thermodynamic constraints. It would be manifest of a perfect crystalline material with minimal amorphous material inclusions.

Currently, the Voyager probes launched in 1977 are at a distance of 136 AU for Voyager 2 and 165 AU for Voyager 1 respectively. Since they have apparently been allowed to pass well beyond the 100 AU distance of our solar heliosphere and are also still transmitting science data to the Deep Space Network, this implies that if any such containment wall were in place, it would have to be much further out, and perhaps well into the Oort Cloud. This would then allow for another century or so of human expansion into space as our probes become more sophisticated technologically.

The above physics and engineering requirements illustrate why zoo containment via a physical shell would be problematic and at first glance it could be argued that the lack of finding such a structure may be seen as a partial falsification of the zoo hypothesis. Clearly this would be a project for an advanced technological civilization that goes way beyond the current state of art for human technological maturity and likely implies a high Kardashev level [37] to construct such a large megastructure if indeed it were ever possible.

Alternatively, there is no containment wall and instead it is an artificial boundary that is in some way policed by ETI probes to monitor what we send out there. But then this does not solve the problem of how to prevent us from detecting the presence of ETI in deep space through our astronomical observatories; unless their cloaking and propulsion technology is so advanced that it is beyond our present comprehension. For example, they could have an ability to dampen electromagnetic and gravitational waves as they move across the Cosmos and head towards us; although it is difficult to imagine how this would be completely impermeable. Overall, this implies a contradiction in our understanding and logic for how we are framing the Fermi Paradox within a zoo hypothesis.

It is possible that ETI exists in abundance, but they have made a joint decision not to engage with humanity or to release evidence of their existence and so this results in a null contact. They continue to remain in a stealth mode and do not share any information with us and only keep us under continued observation for their own security. But the technology used in their engines would have to be based on principles so advanced of our science that emissions such as due to electromagnetic waves would not occur.

In effect such an advanced society would be operating a strategy similar to the Planetarium Hypothesis [38] suggested by the science fiction writer Stephen Baxter where external reality is engineered and all we see a form of illusion. Intelligent extraterrestrial life may be in abundance but all signs of it are hidden from our gaze.

On the assumption that some form of containment policy did exist, from our perspective this might manifest itself in the continued failure of our technology programs which aim to achieve far reaching science goals. The sabotage of our technological advancement was explored in the novel The Three-Body Problem written by Liu Cixin [39]. We may get to a point of constructing an interstellar probe for example, but they will never go beyond a certain speed making journey times too long, or they will simply fail in their mission in deep space away from our ability to observe any sabotage of our vehicles.

After many attempts at trying to cross the interstellar void, and presumably at large economic cost, pressure would build on political systems to cease the attempt in the interest of other priorities. In addition, this would also lead to a belief among humanity that interstellar flight is simply not possible since the challenge is too great. A full stagnation of our technology programs past a certain containment zone in space would have been achieved and we may be none the wiser.

We can make preparations to test the existence of a containment zone by equipping our space probes with the appropriate technology and instrumentation sensors to pick up any deep space objects or interference in our probes. Just recently the Voyager 1 mission experienced a major computer malfunction [40], which after months of effort was fixed by designers at the Jet Propulsion Laboratory by uploading corrective programming. The error was put down to a faulty chip and was likely due to the increased cosmic ray flux as the probe goes further out into the interstellar medium and away from the protection of the solar heliosphere magnetic field. Yet, if there were interference in the probe, how would we know the difference or if indeed it has happened already? [41]. These sorts of issues need to be discussed by mission planners in parallel with planning for post-Voyager missions which have been proposed [42, 43, 44].

Breaking out of the Zoo

The U.S President Ronald Reagan recognised the potential impact of an ETI presence in a speech to the United Nations General Assembly in September 1987 in which he said “I occasionally think how quickly our differences worldwide would vanish if we were facing an alien threat from outside this world” [45]. In his speech he was emphasising how much unites the different groups of humanity rather than what makes us different. An imagined alien threat may have been somewhat over dramatized, but the point is still well made, that our disunion is not just a threat to them, but also to ourselves in creating a just and harmonious society. Indeed, this might be precisely what ETI is waiting for, before any meaningful level of inter-species dialogue can take place between two distinct and original interstellar species.

There is a simpler way to break out of any hypothetical zoo and it is one for which all nations of the world should take notice. If it was the case that there are many intelligent technological civilizations out there, but they choose to contain us, perhaps we should instead seek a path of humility and realise that it is highly improbable that we have more wisdom that the collective minds of many vast civilizations that may have existed for millions of years. Perhaps then this should be a prompt for us to look in the mirror at who we are as a species and who we want to become. To conduct ourselves in a manner that would not invite such a containment policy.

Recently, Western nation’s commemorated eighty years since the Normandy invasion of Europe during World War II and the many brave lives lost in the attempt to secure Europe from the grip of Nazi Germany. A mere two decades prior to this was World War I; the supposed war to end all wars. Looking at the world today in 2024, have we changed that much? For all our technological progress and the great truths uncovered by scientific discovery, isn’t our nature fundamentally the same as it always was? A diverse humanity in conflict with each other. This may simply be a result of our evolution through natural selection and undoing millions of years of our nature may not be a trivial undertaking.

We attempted some progress towards a more peaceful union in the construction of the United Nations in 1945 following World War II, and before that the League of Nations following World War I. At the United Nations, this is where all countries can at least sit at a table together and talk through differences without resorting to conflict. But is this institution working? How many conflicts rage around the world today, where it remains impotent to intervene? The United Nations was a good idea, but it clearly needs fundamental reform.

In issue 48 of The Federalist Papers written by James Madison in 1788, he makes a thought-provoking suggestion: “Happy would it be if such a remedy…could be enjoyed by all free governments; if a project equally effectual could be established for the universal peace of mankind” [46]. Whilst adopting a Federalist system for the whole world may be a step too far at this time, perhaps we can at least strive to increase our democratic union.

There may be another way in which the United Nations can be reformed and could lay the foundations for a more peaceful union that is also democratic, whilst also recognising the sovereignty of individual nation states. That is to address Article 27 of the United Nations Charter where “Each member of the Security Council shall have one vote” [47], for a two-thirds majority, and yet only certain states are given the power of a veto. These are the permanent members who include the United States, United Kingdom, France, Russia and China, all of which also happen to be nuclear armed states.

Historically, when a conflict continues with the loss of much civilian life despite attempts at resolutions by members of the United Nations, one can find evidence of a veto by one of these permanent members. As of spring 2024 the veto has been used a total of 277 times. This is split into 128 (Russia), 85 (United States), 29 (United Kingdom), 19 (China) and 16 (France) [48, 49]. How many conflicts could have been avoided if the veto power was not there?

Removing the veto power of permanent members and allowing each nation to have one vote may be the only way to fully achieve a democratic union of all countries in the world, whilst also protecting individual nation state sovereignty and preventing the homogenisation of a diverse set of rich human cultures, where diversity should also be seen as a factor in generating maximum creativity for problem solving. However, given the very different population sizes of countries some mechanism would be needed to ensure proportional representation. This might be in a manner similar to the method used by the United States Congress where all states have equal representation in the Senate but a proportional representation in the House of Representatives.

Even if a direct removal of this power is not feasible, perhaps there are variations on this idea which might be adopted as an alternative. This might include for example that with the five permanent members, for any veto to be carried forward it must have a majority among those five members, which means three against and two for any resolutions proposed by members. That would at least represent some progress towards a more cohesive union and dilute the right of any one nation to act on its own and prevent the will of a majority.

Is it reasonable that a single member of an institution which has 193 members in total has the power to prevent a resolution by a majority of the other representative? Indeed, this is manifest of Empire building and gives permission for unilateral actions of one state against another; the likes of which has so defined the last century of conflicts.

Instead of removing the veto it could be argued that it should be expanded to include more members, but this was already tried in the original League of Nations, where at one point the League Council included 15 countries with veto power and where it was difficult for decisions to be made on any complex issues. If the veto power is removed entirely from all nations, this would create a much more democratic process and arguably create the conditions for increased problem solving as nation states are forced to negotiate a settlement.

Whilst the veto allows states to act in their own sovereign rights and best national interests, removing it would force more of a consideration for international best interests and taking a broader view of humanity as one people. Is it not time to consider that adherence to a charter of rules-based order is more important than a principle of unanimty? Indeed, this may also be a pathway towards a more democratic union along the lines of the principle of subsidiarity at a local nation state level, but enhanced co-operation at a global level among civilised nations seeking to address common problems on the planet.

For sure removing the veto would come with consequences, particularly to those permanent members. Yet it would prevent for example the attack on one country by another without a much broader coalition agreement.

Where is the moral leadership on planet Earth today? It is certainly not being provided by any of the existing permanent members. Where are the grown-ups demanding people put their weapons down and break bread? This also highlights the ineffectiveness of the world’s religions, powerless to intervene, and lacking in courage to protect those caught in the middle of global conflicts. If any moral code laid down to the people of Earth should prompt them into action, “Thou shalt not kill” is certainly one of them. Yet, no definitive and unambiguous call towards peace is made by the leaders of these religions.

It should not be assumed that the conduct of these nations is not being observed closely with long term consequences to how our species will be permitted to advance, or even stagnated towards extinction in the interest of a higher principle than any for which we are currently aware.

In general, in the modern integrated geopolitical world, it should be harder to take unilateral action by one state against another, and when action is required, it should involve a multilateral approach. This would prevent the excesses of one dominant party against another, but also the moderation caused by the other members would result in a more reasonable approach to problem solving that represents a consensus position. For sure, such a decision would take a significant amount of courage and trust by the permanent members, but perhaps that is the bridge that must be crossed if our world is to become unified.

It has been argued that removing the veto would lead to the withdrawal of the permanent member states since they can no longer defend their security interests [50]. This may be so, but nations cannot have it both ways, they either want to exist in isolation or construct a harmonious existence with other nations, consistent with a peaceful and prosperous future for planet Earth. Faced with the potential contact with ETI in the near future, we should ask ourselves what arrangement would facilitate a better contact scenario? One where ETI is expected to engage in dialogue with 193 separate entities, or one where it engages with a representative body for which all nations have influence?

Imagine if the roles were reversed, and ETI came to our planet, but they came in 193 different missions representing that many different societies among their civilisations. How confusing would we find that? What would it say about their own societies lack of cohesion to give us pause for concern in reaching any agreements?

This all points towards a requirement for radical reforms in the governance model and how its various missions are executed and monitored. After all, for those permanent members that would oppose a removal of the veto, this sort of conduct gives their argument legitimacy. The primary function of the United Nations should be to prevent conflict, broker peace settlements, protect the innocent and help to create the conditions for a more prosperous human condition on this planet Earth.

That said, it is acknowledged that in removing the veto this potentially creates the conditions for a different type of geopolitical environment, where countries now attempt to ‘buy’ others votes by the promising of large infrastructure investment projects that would benefit their society. A form of nation state barter if you like. It would all need careful consideration.

The author also acknowledges that his own understanding for how the United Nations operates may be somewhat naive, and in fact the veto may be acting as a form of linchpin on the entire geopolitical diplomacy effort. To remove it may lead to unstable conditions which are difficult to predict. Nobody is a true predictor of the possible futures that may unfold. Yet, it must also be acknowledged that the existing system is not working.

To emphasise some of the positive achievements of the United Nations, in 2005 a study by the RAND corporation [51] concluded that the United Nations provides the most suitable institutional framework for nation building missions, with an emphasis on a comparatively low-cost structure and success rate, and the one with the greatest degree of international legitimacy. It is also a champion of human dignity through the Universal Declaration of Human Rights, first adopted in 1948.

Currently there is a campaign for a United Nations Parliamentary Assembly as a global network of parliamentarians, non-governmental organizations, scholars and citizens that advocate for democratic representation and an influence over global policy [52]. To date 137 nations have so far endorsed the idea. Such a suggestion might go some way to addressing some of the existing problems, but it depends on whether it has any actual power to influence resolutions.

In terms of our activities in outer space Crawford [53] proposed that a World Space Agency is required, possibly acting under the auspices of a federal world government. If the International Space Station in Low Earth Orbit has achieved one thing it has been demonstrating that different nations around the world can co-operate together behind a shared scientific exploration endeavour. This serves as a beacon of hope for what may be possible when we work together, and especially as humanity begins a new age of space exploration in the settlement of the Moon and Mars.

It is likely that significant reforms to our multilateral institutions would be difficult to implement if there is no will do so. Yet, let us not pretend then that the United Nations represents any form of democracy in action. Although the Charter states the words “We the Peoples of the United Nations” [47] the reality is that it has presided over the DisUnited Nations and continued conflict in international affairs. Until we are prepared as a global community to make the changes required to our governing institutions that leads to a more just world, it may be that for any observing ETI we are considered a threat that is to be contained.

A Cosmic Perspective

This is a planet that is spinning through space suspended in a dance of gravity around the Sun, itself spiralling around the Milky Way galaxy, a mere speck of dust in a vast and infinite universe. As we look at our world, we should be reminded of the words of Carl Sagan who said “Our posturings, our imagined self-importance, the delusion that we have some privileged position in the Universe, are challenged by this point of pale light”. He continued “To me, it underscores our responsibility to deal more kindly with one another, and to preserve and cherish the pale blue dot, the only home we’ve ever known” [54].

As discussed by Deardorff [55] the motivation for any type of containment may be for protecting any existing ETI civilizations from the aggressive tendencies of other emerging species. Any society that exhibits such characteristics will also become self-destructive and so it would be a sensible policy of ETI to not interfere in the development of emerging societies until they can at least demonstrate they can get over this phase of their development and achieve a state of peaceful cooperation with others. If they do become destructive then this would only serve to illustrate their unfitness to join a broader collective.

In the 1951 science fiction film The Day the Earth Stood Still, the alien visitor Klaatu gives a speech to the world. He refers to the creation of a galactic police force of robots that have absolute power over hostile life-forms, but where the conditions are created where civilizations can exist free from aggression and war, free to pursue more profitable enterprises. Klaatu states “It is no concern of ours how you run your own planet, but if you threaten to extend your violence this Earth of yours will be reduced to a burned out cinder” [56]. How would we change if we were really faced with such an ultimatum from outside?

Arthur C Clarke explores this in his 1953 novel Childhood’s End [57] when an alien race known as the Overlords descend to Earth and set about changing it. This includes the creation of a new World Federation using the United Nations to create a golden age of prosperity. Yet, for the humans in the story things do not end well as they eventually say goodbye to their children. When the aliens reveal themselves to humankind, they coincidently have the appearance of the devil, highlighting the illogical prejudice of our species.

In 2023 the United States Congress House Oversight Subcommittee held hearings [58] on the claims of pilots and former federal employees that unidentified anomalous phenomena (UAP) have been seen flying through our atmosphere today. It is interesting to note, following this saga on the social networks since, the suggestion of a spiritual component to the phenomena is being raised by some, with any potential ETI not being seen as our brothers and sisters among the stars, but rather as angels and demons.

Recently, the Vatican has released a document with new guidelines on the norms for discerning alleged supernatural phenomena [59]. Although the supernatural phenomena of interest to the Catholic Church is multi-varied as miracles, they also include the possible of ETI as divine apparitions.

It is these kinds of speculations which have a propensity to cause disharmony in human relationships and prevent our species from indeed achieving childhoods end. One must wonder what Carl Sagan would have thought about all this when he wrote his 1995 book The Demon-Haunted World [60] in an apparent reference to the irrationality of human thinking. Heaven and Hell do exist, and they exist simultaneously here on Earth today, manifest of our actions or inactions and “With our thoughts we create the world” [61].

In 1945 atomic bombs were dropped on the Japanese cities of Hiroshima and Nagasaki and with the hundreds of thousands of deaths that followed certainly hell on Earth existed for them. Today, in our world of global conflicts there exists over 13,000 nuclear warheads in stockpiles around the world which have a combined energy of around 4,000 Mtons TNT equivalent. Asteroids will hit the Earth with a velocity of between 18 – 30 km/s depending on their origin. Assuming such a spherical object was made entirely of Iron with a density of 7,890 kg/m³, with this total energy it would have a diameter of around ~200-300 m across – equivalent to several football sized fields and where the environmental consequences of such an impact would be devastating.

Depending on the impact angle, ground target density and material, the impact would make a crater perhaps as large as 10 km in diameter and generate global environmental effects that are too profound to consider. In the distant future a new intelligence species may evolve on Earth and they would find themselves studying the fossilized remains of Homo Sapiens the way that we study the dinosaurs that disappeared 66 million years ago.

Given the conflicts that still rage around our planet, it is nothing short of insanity that we risk escalation where a new extinction level event presents a real and present danger as an existential threat to our species. If the United Nations is to have a function, it surely must be to prevent such a scenario as this from ever happening, and if it does happen, we can surely point to the Permanent Members as complicit in humanity’s destruction.

The Permanent Members of the United Nations are a result of winning World War II and they have helped to create the modern world that we live in and the periods of stability that we do enjoy. Yet they are also creating the conditions for instability by their conduct in the world and the constant wars, imposed ideologies and atrocities as crimes against humanity. Instead, imagine a future where instead of fighting each other, they were working towards a peaceful co-existence on Earth and in space; as they have done in the exploration of Antarctica and with the International Space Station. Imagine a future where we were building colonies on the Moon, the first cities on Mars, exploring the outer planets and beyond. What new discoveries await us as a grand prize in those undiscovered lands of hope?

Although it cannot be proven, it is possible that the Cosmos has a fundamental qualification for becoming a part of it instead of just being constrained to one planetary biosphere. Those that engage in disunion, conflict and war are not welcome among the intelligent life forms so natural to the stars. For those that engage in peaceful co-operation with each other and construct a union among a civilised people who value creativity, imagination and compassion to each other, even infinity defines no boundary to what may be achieved.

Perhaps only when we step up and recognise the changes that are required within ourselves, will ETI be prepared to fully engage with us. A global multilateral institution like the United Nations is clearly a primary candidate for such change, and if is not, then it is at least complicit in the disharmony of our world. Until then, like animals in a zoo, the broader truths of the wider universe may forever be hidden from our gaze.

Summary

The possible discovery of ETI is one of the most exciting pursuits of the scientific endeavour which will also have profound implications for our social-culture and our understanding of the Cosmos. Yet, whilst we search with enthusiasm for them, we should not be so sure that they are also keen to meet us. This is due to our nature and the tendency to construct technologies which can be used for the purpose of destruction rather than creation. This would be of grave concern to any ETI that exists in our galaxy which values self-preservation and life.

On the assumption that they do exist, and they also have concerns about us, we have speculated on the possibility that a zoo containment policy may be in place around our solar system and surrounding nearby space. Although we have also suggested that a physical containment zoo would be impractical to implement.

To ensure that containment, it may be necessary for ETI to take direct actions to limit our technology growth or the reach of that technology into deep space. This could be through methods of sabotage or other clandestine operations hidden from our view that ultimately result in the moderation of our capability to go further and faster. As President Reagan once said “Perhaps we need some outside, universal threat to make us recognize this common bond” [45]. Yet, they may already be here, and we would be extremely wise to pause and take notice. Benford has suggested that perhaps we should be looking for ETI lurkers within our own solar system and this idea has merit [62].

Since humanity is now reaching a point where certainly missions that travel at speeds of 100 km/s are possible today, and much higher speeds of order 1,000s km/s appear possible towards the end of this century, it would be prudent for us to build protection mechanisms into our space probes to detect the presence of ETI or their attempts to interfere in our space probes. This might include booby-traps in our software programming, or technology sensors which can detect their presence. Whilst this possibility may seem fantastic, this would be the most sensible way to test if a zoo hypothesis containment policy were in action around our solar system.

Meanwhile, it would be a sensible policy to encourage the better angels of our nature and maintain the bonds of affection between nations that are so essential to a peace-loving society which promotes compassion and wisdom as the defining characteristics of what it means to be a human being in a vast and expanding Cosmos, where we may not be alone. As the great scientist Albert Einstein said “Our task must be to free ourselves from this prison by widening our circle of compassion to embrace all living creatures and the whole of nature in its beauty” [63].

Any change is likely to necessitate fundamental reforms to our existing multilateral institutions. It is also likely to require the emergence of a new and inspirational moral leadership class that is currently in abeyance. It could be argued that the lack of moral leadership creates the conditions for global conflict and disunion among an otherwise peaceful people. In relation to space, it should certainly be our task “to avoid the extension of present national rivalries into this new field” [64].

Ultimately, the nations of the world must decide “whether societies of men are really capable or not, of establishing good government from reflection and choice, or whether they are forever destined to depend, for their political constitutions, on accident and force” [65]. A change to the status quo at the United Nations may be the only hope for humanity as we look out upon the precipice of either our fate or our destiny. One of these futures is waiting for us.

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Every time I mention a Brian Aldiss novel, I have to be careful to check the original title against the one published in the US. The terrific novel Non-Stop (1958) became Starship in the States, rather reducing the suspense of decoding its strange setting. Hothouse (1962) became The Long Afternoon of Earth when abridged in the US following serialization in The Magazine of Fantasy & Science Fiction. I much prefer the poetic US title with its air of brooding fin de siècle decline as Aldiss imagines our deep, deep future.

Imagine an Earth orbiting a Sun far hotter than it is today, a world where our planet is now tidally locked to that Sun, which Aldiss describes as “paralyzing half the heaven.” The planet is choked with vegetation so dense and rapidly evolving that humans are on the edge of extinction, living within a continent-spanning tree. The memory of reading all this always stays with me when I think about distant futures, which by most accounts involve an ever-hotter Sun and the eventual collapse of our biosphere.

Image: The dust jacket of the first edition of Brian Aldiss’ novel Hothouse.

Indeed, warming over the next billion years will inevitably affect the carbon-silicate cycle. Its regulation of atmospheric carbon dioxide is a process that takes CO2 all the way from rainfall through ocean sediments, their subduction into the mantle and the eventual return of CO2 to the atmosphere by means of volcanism. Scientists have thought that the warming Sun will cause CO2 to be drawn out of the atmosphere at rates sufficient to starve out land plants, spelling an end to habitability. That long afternoon of Earth, though, may be longer than we have hitherto assumed.

A new study now questions not only whether CO2 starvation is the greatest threat but also manages to extend the lifetime of a habitable Earth far beyond the generally cited one billion years. The scientists involved apply ‘global mean models,’ which help to analyze how vegetation affects the carbon cycle. Lead author Robert Graham (University of Chicago), working with colleagues at Israel’s Weizmann Institute of Science, is attempting to better understand the mechanisms of plant extinction. Their new constraints on silicate weathering push the conclusion that the terrestrial biosphere will eventually succumb to temperatures near runaway greenhouse conditions. The biosphere dies from simple overheating rather than CO2 starvation.

The implications are intriguing and offer fodder for a new generation of science fiction writers working far-future themes. For in the authors’ models, the lifespan of our biosphere may be almost twice as long as has been previously expected. Decreases in plant productivity act to slow and eventually (if only temporarily) reverse the future decrease in CO2 as the Sun continues to brighten.

Here’s the crux of the matter: Rocks undergo weathering as CO2 laden rainwater carrying carbonic acid reacts with silicate minerals, part of the complicated process of sequestering CO2 in the oceans. The authors’ models show that if this process of silicate weathering is only weakly dependent on temperature – so that even large temperature changes have comparatively little effect – or strongly CO2 dependent, then “…progressive decreases in plant productivity can slow, halt, and even temporarily reverse the expected future decrease in CO2 as insolation continues to increase.”

From the paper:

Although this compromises the ability of the silicate weathering feedback to slow the warming of the Earth induced by higher insolation, it can also delay or prevent CO2 starvation of land plants, allowing the continued existence of a complex land biosphere until the surface temperature becomes too hot. In this regime, contrary to previous results, expected future decreases in CO2 outgassing and increases in land area would result in longer lifespans for the biosphere by delaying the point when land plants overheat.

How much heat can plants take? The paper cites a grass called Dichanthelium lanuginosum that grows in geothermal settings (with the aid of a symbiotic relationship with a fungus) as holding the record for survival, at temperatures as high as 338 K. The authors take this as the upper temperature limit for plants, adding this:

Importantly, with a revised thermotolerance limit for vascular land plants of 338 K, these results imply that the biotic feedback on weathering may allow complex land life to persist up to the moist or runaway greenhouse transition on Earth (and potentially Earth-like exoplanets). (Italics mine)

The long afternoon of Earth indeed. The authors point out that the adaptation of land plants (Aldiss’ continent-spanning tree, for example) could push their extinction to even later dates, limited perhaps by the eventual loss of Earth’s oceans.

…an important implication of our work is that the factors controlling Earth’s transitions into exotic hot climate states could be a primary control on the lifespan of the complex biosphere, motivating further study of the moist and runaway greenhouse transitions with 3D models. Generalizing to exoplanets, this suggests that the inner edge of the “complex life habitable zone” may be coterminous with the inner edge of the classical circumstellar habitable zone, with relevance for where exoplanet astronomers might expect to find plant biosignatures like the “vegetation red edge” (Seager et al. 2005).

The paper is Graham, Halevy & Abbot, “Substantial extension of the lifetime of the terrestrial biosphere,” accepted at Planetary Science Journal (preprint).