by Paul Gilster | Dec 21, 2016 | Astrobiology and SETI |
I love watching people who have a passion for science constructing projects in ways that benefit the community. I once dabbled in radio astronomy through the Society of Amateur Radio Astronomers, and I could also point to the SETI League, with 1500 members on all seven continents engaged in one way or another with local SETI projects. And these days most everyone has heard the story of Planet Hunters, the citizen science project that identified the unusual Boyajian’s Star (KIC 8462852). When I heard from Roger Guay and Scott Guerin, who have been making their own theoretical contributions to SETI, I knew I wanted to tell their story here. The post that follows lays out an alien civilization detection simulation and a tool for visualizing how technological cultures might interact, with an entertaining coda about an unusual construct called a ‘Dyson shutter.’ I’m going to let Roger and Scott introduce themselves as they explain how their ideas developed.
by Roger Guay and Scott Guerin
Citizen Science plays an increasingly important role across several scientific disciplines and especially in the fields of astronomy and SETI. Tabby’s star, discovered by members of the Planet Hunters project and the SETI@home project are recent examples of massively parallel citizen-science efforts. Those large-scale projects are counterbalanced by individuals whose near obsession with a subject compels them to study, write, code, draw, design, talk about, or build artifacts that help them understand the ideas that excite them.
Roger Guay and Scott Guerin, working in isolation, recently discovered parallel evolution in their thinking about SETI and the challenges of interstellar detection and communication. Guay has undertaken the programming of a 10,000 x 8,000 light year swath of a typical galaxy and populates it with random radiating communicating civilizations. His model allows users to tweak basic parameters to see how frequently potential detections occur. Guerin is more interested in a galaxy-wide model and has used worksheets and animations to bring his thoughts to light. His ultimate goal is to develop a parametric civilization model so that interactions, if any, can be studied. However, at the core, both efforts were attempts at visualizing the Fermi Paradox across space-time, and both experimenters show how fading electromagnetic halos may be all that’s left for us to discover of an extraterrestrial civilization, if we listen hard enough.
The backgrounds, mindsets, and tool kits available to Roger and Scott play an important role in their path to this blog.
Roger Guay
I am a retired Physicist and Technical Fellow Emeritus from Boeing in Seattle. I can’t remember when I first became interested in being a scientist (it was in grade school) but I do remember when I first became obsessed with the Fermi paradox. It was during a discussion while on a road trip with a colleague. At first, this discussion mainly revolved around the almost unfathomable vastness of space and time in our galaxy, but then turned to parameters of the Drake equation. The one that was the most controversial was L, the lifetime of an Intelligent Civilization or IC.
The casual newcomer to the Drake equation will tend to assume a relatively long lifetime for an IC, but when considering detection methods such as SETI uses, one must adjust L to reflect the lifetime of the technology of the detection method. For example, SETI is listening for electromagnetic transmissions in the microwave to radio and TV range. So, L has to be the estimated lifetime of that technology. For SETI’s technology, we’ll call this the Radio Age. On Earth, the Radio Age started about 100 years ago and has already fallen off due to technological advances such as the internet and satellite communication. So I argued, an L = 150 ± 50 years might be a more reasonable assumption for the Drake equation when considering the detection method of listening for radio signals.
At this point the discussion was quite intense! When I thought about an L equal to a few hundred years in a galaxy that continues to evolve over a 13-billion-year lifespan, the image that came to my mind was that of fireflies in the night. And that was the precursor for my Alien Civilization Detection or ACD simulation.
One can imagine electromagnetic or “radio” bubbles appearing randomly in time and space and growing in size over time. At any instant in time the bubble from an IC will have a radius equal to the speed of light times the amount of time since that IC first began broadcasting. These bubbles will continue to grow at the speed of light. When the IC stops broadcasting for whatever reason, the bubble will become hollow and the shell thickness will reflect the time duration of that IC’s Radio Age lifetime.
If the age of our galaxy is compressed into one year, we on Earth have been “leaking” radio and television signals into space for only a small fraction of a second. And, considering the enormity of space and the fact that our “leakage” radiation has only made it to a few hundred stars out of the two to four hundred billion in our galaxy, one inevitably realizes there must be a significant synchronization problem that arises when ICs attempt to detect one another. So what does this synchronicity problem look like visually?
To answer this question my tasks became clear: dynamically generate and animate radio bubbles randomly in space and time, grow them at the speed of light at very fast accelerated rate in a highly compressed region of the galaxy, fade them over time for inverse square law decay, and then analyze the scene for detection. No Problem!!!
Using LiveCode, a modern derivative of HyperCard on steroids, I began my 5-year project to scientifically simulate this problem. Using the Monte Carlo Method whereby randomly generated rings denoting EM radiation from ICs pop into existence in a 8,000 X 10,000 LY region of the galaxy* centered on our solar system at a rate of about 100 years per second, the firefly analogy came to life. And the key to determining detection potential is to recognize that it can only occur when a radiation bubble is passing over another IC that is actively listening. This is the synchronicity problem that is dramatically apparent when the simulation is run!
To be scientifically accurate and meaningful, some basic assumptions were required:
- 1. ICs will appear not only randomly in space, but also randomly in time.
- 2. ICs will inevitably transition into (and probably out of) a Radio/TV age where they too will “leak” electromagnetic radiation into space.
- 3. The radio bubbles are assumed to be spherically homogeneous**.
To use the ACD simulation, the user chooses and adjusts parameters such as Max Range, Transmit and Listen times*** and N, the Drake equation estimate of the number of ICs in the galaxy at any given instant. During a simulation run, potential detections are tallied and the overall probability of detection is displayed.
About two years ago, as the project continued to evolve, I became aware of Stephan Webb’s encyclopedic book on the Fermi Paradox, If the Universe is Teeming with Aliens … Where is Everybody? This book was most influential in my thinking and the way I shaped the existing version of the ACD simulation.
A snapshot of the main screen of the ACD simulation midway through a 10,000 year run.
A Webb review of the ACD simulation is available here: http://stephenwebb.info/category/fermi-paradox/
And you can download it here at this Dropbox link:
https://www.dropbox.com/sh/dlkx24shyfjsoax/AADeFd2wZyZxvLYHU2f4jJ0ha?dl=0
Conclusions? The ACD simulation dramatically demonstrates that there is indeed a synchronicity problem that automatically arises when ICs attempt to detect one another. And for reasonable (based on Earth’s specifications) Drake equation parameter selections, detection potentials are shown to be typically hundreds of years apart. In other words, we can expect to search for a few hundred years before finding another IC in our section of the galaxy. When you consider Occam’s razor, is not this synchronicity problem the most logical resolution to the Fermi Paradox?
Footnotes:
* The thickness of the Milky Way is small compared to its diameter. So for regions close to the center of the thickness, we can approximate with a 2-dimensional model.
** Careful consideration has to be given to this last assumption: Of course, it is not accurate in that the radiation from a typical IC is assumed to be composed of many different sources and have widely varying parameters, as they are on Earth. But the bottom line is that the homogenous distribution gives the best case scenario of detection potential. An example of when to apply this thinking is to consider laser transmission vs radio broadcast. Since a laser would presumably by highly directed and therefore more intense at greater distances, the user of the ACD simulation might choose a Higher Max Range but at the same time realize that pointing problems will make detection potential much smaller than the ACD indicates. The ACD does not take this directly into consideration. Room for the ACD to grow?
*** One of the features of this simulation is that the user can make independent selections of both the transmit and listening times of ICs, whereas the Drake equation lumps them together in the lifetime parameter.
Scott Guerin
I grew up north of Milwaukee, Wisconsin and was the kid in 5th grade who would draw a nuclear reactor on the classroom’s chalkboard. My youthful designs were influenced by Voyage to the Bottom of the Sea, Lost in Space, everything NASA, and 2001: a Space Odyssey. In the mid 70s, I was a technical illustrator at the molecular biology laboratory at UW Madison and, after graduation with a fine arts degree, I went on to a 30-year career as an interpretive designer of permanent exhibits in science and history museums.
I began visually exploring SETI over two years ago in order to answer three questions: First, why is such a thought-provoking subject so often presented only in math and graphs thereby limiting information to experts? Secondly, why is the Fermi Paradox a paradox? Thirdly, what form might an interstellar “we are here” signaling technology take?
Using Sketchup, I built a simple galactic model to see what scenarios matched the current state of affairs: silence and absence. At a scale of 1 meter = 1 light year, I positioned Sol appropriately, and randomly “dropped” representations of civilizations (I refer to them as CivObjects) into the model. Imagine dropping a cup full of old washers, nails, wires, and screws onto a flat, 10″ plate and seeing if any happen to overlap with a grain-of-salt-sized solar system (and that speck is still ~105 too large).
The short answer is that they didn’t overlap and I’ve concluded that the synchronicity issue, combined with weak listening and looking protocols is a strong answer to the paradox. When synchronicity is considered along with sheer rarity of emitting civilizations (my personal stance), the silence makes even more sense.
For scale, the green area at lower right represents the Kepler star field if it were a ~6,000 LY diameter sphere. The solid discs represent currently emitting civilizations, the halos represent civilizations that have stopped emissions over time, and the lines and wedges represent directed communications. I sent this diagram to Paul and Marc at Centauri Dreams who were kind enough to pass it on to several leading scientists and they graciously, and quickly, replied with encouragement.
Curtis Charles Mead’s 2013 Harvard dissertation “A Configurable Terasample-per-second Imaging System for Optical SETI,” George Greenstein’s Understanding the Universe, Tarter’s, and the Benford’s papers, among others, were influential in my next steps. I realized the halos were unrealistic representations of a civilization’s electromagnetic emissions and that if you could see them from afar, they could be visualized as prickly, 3-dimensional sea urchin-like artifacts with tight beams of powerful radar, microwave, and laser emanating from a mushy sphere of less directional, weaker electromagnetic radiation.
From afar, Earth’s EM halo is a lumpy, flattened sphere some 120LY in radius dating to the first radio experiments in the late 1890’s. The 1974 Arecibo message toward M13 is shown being emitted at the 10 o’clock position.
From Tarter’s 2001 paper “At current levels of sensitivity, targeted microwave searches could detect the equivalent power of strong TV transmitters at a distance of 1 light year (the red sphere at center in the diagram), or the equivalent power of strong military radars to 300 ly, and the strongest signal generated on Earth (Arecibo planetary radar) to 3000 ly, whereas sky surveys are typically two orders of magnitude less sensitive. The sensitivity of current optical searches could detect megajoule pulses focused with a 10-m telescope out to a distance of 200 ly.”
In this speculative diagram, two civilizations “converse” across 70 LY. Mead’s paper confirms the aiming accuracy needed to correct for the the proper motion of the stars, given a laser beam just a handful of AU wide at the distance illustrated, is within human grasp. The civilizations shown would most likely have been emitting EM for hundreds of years so that their raw EM halos are so large and diffuse they cannot be shown in the diagram. The magenta blob represents the elemental EM “hum” of a civilization within a couple LY, the green spikes represent tightly beamed microwaves for typical communications and radar , while the yellow spikes are lasers reaching out to probes, being used as light-sail boosters, and fostering long distance high-bandwidth communications. Each civilization has an EM fingerprint, affected by their system’s ecliptic angle and rotation, persistence of ability, and types of technologies deployed — these equate to a unique CivObject.
In advance of achieving the goal of a fully parametric 3D model, I manually animated several kinds of civilizations and their interactions by imagining a CivObject as a variant of a Minkowski space-time cone. I move the cone’s Z axis (time) through a galactic hypersurface to illustrate a civilization’s history of passive and intentional transmission, as well as probes at sub-lightspeed. A CivObject’s anatomy reveals the course of a civilization’s history and I like to think of them as distant cousins of Hari Seldon’s prime radiant. https://vimeo.com/195239607 password: setiwow!
The anatomy of a CivObject allows arbitrary time scales to be visualized as function of xy directionality, EM strength, and type of emission. Below is Earth’s as a reference. Increasing transmission power is suggested by color.
I found it easy to animate transmissions but continue to struggle with visualizing periods of listening and the strength of receivers. Like Guay, I concluded that a potential detection can occur only when a transmission passes through a listening civilization. A “Conversing” model designed to actually simulate communication interactions needs to address both ends of “the line” with a full matrix of transmitter/receiver power ratios as well as sending/listening durations, directions, sensitivities, and intensities. In addition, a more realistic galactic model including 3d star locations, the GHZ, and interstellar extinction/absorption rates is needed.
And now for some sci-fi
A few months before KIC 8462852 was announced and Dyson Swarms became all the rage, I noticed one of those old ventilators on top of a barn roof and thought that if a Kardashev II civilization scaled it up to +-1AU diameter, it would become a solar powered, omni-directional signalling device capable of sending an “Intelligence was here” message across interstellar space. I called it a Dyson Shutter.
Imagine a star surrounded by a number of ribbon-like light sails connected at their poles. Each vane’s stability, movement, and position is controlled by the angle of sail relative to incoming photons from the central star. The shutter would be a high tech, ultra-low bandwidth, scalable construct. I have imagined that each sail, at the equator, would be no less than one Earth diameter wide which is at the lower end of Kepler-grade detection.
Depending on the number constructed, the vanes could be programmed to shift into simple configurations such as fibonacci and prime number sequences.
I imagine the Dyson Shutter remains in a stable message period for hundreds of rotations. Perhaps there are “services” for the occasional visitor, perhaps it has defenses against comets, incoming asteroids, or inter-galactic graffiti artists. Perhaps it is an intelligent being itself but is it a lure, a trap, a collector, or colleague? Is it possible Tabby’s star is a Dyson Shutter undergoing a multi-year message reconfiguration?
The shutter’s poles are imagined to be filled with command and control systems, manufacturing facilities, spaceports, etc.
Wrap
We hope that our work as presented here might inspire some of you to join the ranks of the Citizen Scientist. There are many opportunities and science needs the help. With today’s access to information and digital tools, anyone with a little passion for their ideas and a lot of imagination and persistence can help communicate complex issues to the public and make contributions to science. We hope that our stories resonate with at least some of you. Please let us know what you think and let’s all push back on the frontiers of ignorance!
by Paul Gilster | Oct 4, 2024 | Astrobiology and SETI |
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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