Alien Life and Planet Earth

When he redesigned the cosmos, Descartes diminished the significance of human beings by opening up the possibility of life elsewhere. The concept of multiple universes was strange and new, but by the middle of the eighteenth century, many natural philosophers believed not only that they existed, but also that they provided homes for intelligent beings.

"Science: A Four Thousand Year History"
Patricia Fara (2009)1

1. The Chances of Life in the Universe

Extra-terrestrials have been imagined for at least 2300 years, if not longer. Epicurus wrote to Herodotus in 300BCE proposing there could be "infinite worlds both like and unlike this world of ours", even ones inhabited by "living creatures and plants and other things we see in this world"2. The foremost evolutionary biologist, Prof. Richard Dawkins, makes some comments on the likelihood of life evolving on alien planets:

It has been estimated that there are between 1 billion and 30 billion planets in our galaxy, and about 100 billion galaxies in the universe. Knocking a few noughts off for reasons of ordinary prudence, a billion billion is a conservative estimate of the number of available planets in the universe. Now, suppose the origin of life, the spontaneous arising of something equivalent to DNA, really was a staggeringly improbable event. Suppose it was so improbable as to occur on only one in a billion planets. [...] Even with such absurdly looking odds, life will still have arisen on a billion planets - of which Earth, of course, is one. [...]

One can (and Carl Sagan did) make a sober assessment of what we would need to know in order to estimate the probability [of life elsewhere in the Universe, using the Drake Equation]. It states that to estimate the number of independently evolved civilizations in the universe you must multiply seven terms together. [...] When so many terms that are either completely or almost completely unknown are multiplied up, the product - the estimated number of alien civilizations - has such colossal error bars that agnosticism seems a very reasonable, if not the only credible stance.

Some of the terms in the Drake Equation are already less unknown than when he first wrote it down in 1961. At that time, our solar system of planets orbiting a central star was the only one known [...]. At the time of writing we now know of 170 extra-solar planets orbiting 147 stars, but the figure will certainly have increased by the time you read this.

"The God Delusion" by Prof. Richard Dawkins (2006)3

At the pessimistic end of the spectrum, cold-era politics lent a new skeptical air to the theories on life in the universe. What if all advanced life develops destructively powerful nuclear weapons and destroys itself?

Book CoverBy the end of World War II, many scientists believed that life must exist elsewhere - after all, there are 100 billion stars in our galaxy alone, so why should planet Earth be unique? For Enrico Fermi, the Italian nuclear physicist who had helped to develop America's atomic bomb, this argument contained a fatal flaw. How come, he asked, that we found no evidence of any extraterrestrial beings? [...] In the aftermath of Hiroshima, a more sinister solution emerged: could the evolution of intelligence entail a built-in tendency towards self-destruction?

"Science: A Four Thousand Year History" by Patricia Fara (2009)4

However this argument does not surface much in the modern era, as it presupposes that all life follows the same development; and this is something that we simply have no information about. There are various reasons why we may have not yet detected life:

2. UFOs Are Probably Not Aliens

2.1. Is There Intelligent Life on Earth?

[UFOs] tell us absolutely nothing about intelligence elsewhere in the universe, but they do prove how rare it is on Earth.

Arthur C. Clarke5

Picture of stars with a caption: If we ever travel thousands of light years to a planet inhabited by intelligent life, let's just make patterns in their crops and leave.

Unluckily, the distances between stars and galaxies in the Universe are so unimaginably large that, although hopeful data hints at a large number of inhabited planets, it is still unlikely that there is life nearby or even within the traveling distance of a hundred lifetimes. Even at the speed of light, the distances involve make traveling to alien planets a one-way journey. Out of all the UFO sightings, where there has been reliable evidence it has tended to lend itse8lf to terrestrial explanations rather than extra-terrestrial ones6. Where there is no evidence, though, many people cling, out of hope or fear, to the idea that UFOs are aliens. It seems that in the absence of evidence people assume that 'sightings' are aliens even though, wherever evidence has emerged, it has pointed to Earthlings as the source.

2.2. The UFO Craze Was Created by Sensationalist Media and Hoaxes

A critical analysis of the modern mass media:

"The Worst of the Modern Mass Media" by Vexen Crabtree (2009)

It is common sense that the popular press play up and exaggerate stories, including (and especially in previous decades) when it comes to UFOs. The press behaved in the same way as it did with other 'moral panics' - with much sensationalism, and with disregard for evidence7. But it wasn't until I read the research of Martin Gardner that I realized just how much of a role imaginative newspaper editors had played in the creation of the UFO craze. It started in 1947, when Kenneth Arnold saw 9 small weather balloons that were strung together, 'flying' in formation in the sky. The papers came up with the idea of 'flying saucers' on their own, and henceforth, enthusiastically published hyped-up articles attributing all unidentified flying objects to mysterious advanced technology and aliens. It was a science-fiction decade, with a popular press to match.

Aside from the press, hoaxes added to the numbers of reports. Three military men lost their lives investigating UFOs such as those seen near Maury Island. Gardner reports that "the entire Maury Island episode later proved to be a hoax elaborately planned by two Tacoma men who hoped to sell the phony yarn to an adventure magazine. Both men eventually made a full confession"8.

Book CoverAt first the military forces brushed aside the flying-saucer mania as mass delusion, but after the reports grew to vast proportions, the Air Force set up a "Project Saucer" to make a careful investigation. After fifteen months they reported they had found no evidence which could not be explained as hoaxes, illusions, or misinterpretations or balloons and other familiar sky objects. [...]

A book could be written about flying saucer hoaxes perpetrated in the past few years by pranksters, publicity seekers, and psychotics. Unfortunately, exposure of the hoax seldom catches up with the original story.

Even more difficult to expose are the semi-lies - accounts which have a basis in fact, but may be grossly exaggerated. For example, an observer sees a balloon but is convinced it is a saucer. Others are skeptical and this irritates him. So to convince them, he adds details, or exaggerates what he has seen. He may do this without being aware of it, and later recall the episode not as he saw it, but as he has added to it in his desire to convince himself and others. This is a well-known human failing and there is no reason to suppose it could be involved in hundreds of so-called saucer sightings.

"Fads & Fallacies in the Name of Science" by Martin Gardner (1957)8

2.3. What We Learn From Skyhook Balloons

We all suffer from systematic cognitive dysfunctions; they infuse the very way we notice and analyse data, and distort our forming of conclusions. Even our very perceptions are effected by pre-conscious cognitive factors [...]. Our brains were never meant to be the cool, rational, mathematical-logical computers that we like to sometimes pretend them to be.

"Errors in Thinking: Cognitive Errors, Wishful Thinking and Sacred Truths" by Vexen Crabtree (2008)

Investigation of UFOs has always found, where evidence is available, that the source of the sighting is an optical illusion, a result of human error or misunderstanding, or normal skybound objects that the observer has mistaken for something spooky. The example of Skyhook balloons teaches us much about the human predisposition to prefer exciting and stimulating theories to normal and mundane ones. First, the basics:

[In 1951 Feb] the Office of Naval Research distributed a ten-page report on the Navy's huge skyhook balloons, used for cosmic-ray research. The report pointed out in detail the ease with which these giant plastic bags - a hundred feet in diameter - could be mistaken for flying disks. The balloons reach a height of 100,000 feet, and are often borne by jetstream winds at speeds of more than 200 miles per hour. If the observer guesses the balloon to be farther away than it is, then, of course, estimates of speed can be incredibly high.

At a distance, a balloon loses entirely its three-dimensional spherical aspect. It takes on the appearance of a disk [and] a globular object viewed through a telescope looks remarkably like a plate. [...] The plastic composition of a skyhook balloon offers a surface that seems highly metallic in reflected sunlight. Most of the saucer reports describe the disks as silvery in color. At sunset the balloons may shine in the sky for thirty minutes after the earth has become dark [due to their height]. "If your imagination soars," the Navy release said, "[...] The wisp of the balloon's instrument-filled tail may impress you as the exhaust. The sun's rays may suffuse the plastic bag to a fiery glow" [...].

One of the few points on which all observers of flying saucers agree is that there is no noise. This excludes, of course, any known type of propulsion, but is precisely the way a balloon behaves. Observers have sometimes insisted that what they saw could not be a balloon because it was moving against the wind. They forget that wind directions in the stratosphere may be quite different from wind directions on the ground. [...]

The first skyhooks went up in 1947, the year flying saucers were first reported. [...]

At the time of the Navy's report, 270 skyhooks had been released from various spots in the United States, often remaining in the sky more than thirty hours. Frequently, lost balloons were actually traced by following press reports of flying saucer sightings!

"Fads & Fallacies in the Name of Science" by Martin Gardner (1957)8

We are inclined towards seeing things in a more dramatic and exciting light. We learn that before concluding extraordinary things, we should first check our basic perceptions and thinking processes because our perceptions and ideas can cause us to fool ourselves.

3. Communication with Aliens

3.1. A Very Slow Affair

Let us presume that we have detected intelligent aliens, 100 light-years away. This is not a long way but still covers a thousand stars and their planets. If we want to communicate with someone who we know exists, who probably do not know we exist we must first attract their attention. Someone could be trying to contact us but so far we could have missed the signal by unfortunately not facing a receiver in the correct direction!

If we sent a message to them it would take 100 years to get there. They would have to detect it and then send one back, which would take another 100 years. This means that a reply would take 200 years from the time our first message was sent. This is the fastest possible two-way communication allowed by the laws of physics. And this assuming they are close by. We would have to keep scanning from about 190 yrs after our first message up to 250 years after our transmission to see if they have replied to our one message. We would have to keep re-sending the signal for the 100 years in case they have not detected it yet! Only when we receive a response could we stop resending the original signal. Even if we did discover intelligent alien life in our lifetimes we certainly would not be alive to learn the outcome. If Human life was extended to beyond 200 years on average then perhaps it would seem more exciting - the prospect of still being alive when we are expecting an answer!

How long would it take us to establish a dictionary of mathematical terms with which to communicate? Depending on the length of the transmissions (they would have to be highly repetitive in order to be easily recognizable and to prevent data corruption) it could take well over a thousand years to learn anything about them, or them about us, apart from the fact that we both have well-financed radio astronomers and reasonable mathematicians.

If we receive transmissions from further away, they could have been sent thousands or even millions of years ago. We have to consider the very likely possibility that by the time signals have bounced around the Universe for long enough to accidentally stumble upon the antenna of an intelligent species, the original sender, their planet, and their sun, are all extinguished, and such a frustrating event is one that sorely worries astronomers and scientists9.

3.2. Our Transmissions into Space Already Span 100 Light Years

On the other hand, luckily, our transmissions into space actually got a head start on our present intention to find life in the Universe:

Humans have been sending radio waves into space at the speed of light for nearly one hundred years now. Although our goal has seldom been interstellar communication, radio is especially appropriate to that task because electromagnetic waves generally require no travel media, and because radio waves penetrate very efficiently through gas and dust clouds. To date, our "radio bubble," as Tyson calls it, encompasses every star around which a planet has thus far been found, including Alpha Centauri, at 4.3 light-years away; Sirius, our sky's brightest star at ten light-years out; and about a thousand others. So, if aliens are listening, they might have an opportunity to partake in any message sent at frequencies greater than twenty megahertz, including FM radio and television.

Kenneth W. Krause in Skeptical Inquirer (2007)10

The mechanics of listening to such weakened signals requires massive effort, massive receivers pointing in the right direction, "and, if the yearning stargazer actually wanted to decode our message's content, it would have to first adjust for Doppler's shifts caused by Earth's rotation and revolution, and then build a dish about twenty miles wide, or four hundred times Arecibo. That's a lot of work - and for what? A weekly dose of Desperate Housewives and reruns of Welcome Back, Kotter"6.

So although we might despair at the vastness of space, the remoteness of life on Earth and the incredible chances against radio waves happening to travel from one inhabited planet to another, we might also get lucky. I explore the potential results of discovering alien intelligence in: "Discovering Alien Intelligence: The Politics of War and Fear" by Vexen Crabtree (1999).

3.3. The Limits of SETI Over Radio11

Searching for aliens via their radio emissions may not prove to be that useful. Satellites and probes which we have sent into space transmit their radio signals in a directional manner (which saves energy) back towards the Earth, meaning, that often our transmission don't just spread across the Galaxy, but head straight for Earth. It would take an incredible stroke of luck for such intelligently directed signals to be intercepted or spotted by anyone that they were not directed at. Likewise we are unlikely to accidentally stumble across alien communication channels - the alien planet's network of satellites and spaceships, needless to say, will do most of their communicating (just like ours) by transmitting directly to their home world(s).

The same problem occurs with our own "radio bubble", expanding outwards from Earth. Unlike terran omnidirectional antennas, our transmissions that escape into space are not omnidirectional. Our radio bubble is not like a detectable shockwave, but rather, like a very thinly spread net. Signals in space do not spread out the further they travel, like they do within a planet's atmosphere. With no media such as air to travel through, radio signals travel in long, but very thin, straight lines. You have to be within the direct path of this lightspeed needle in order to detect it. "When you consider that entire galaxies can pass through one another without any stars colliding, you can get some idea of how empty the universe is. [...] Any signal from any planet in the universe broadcast in any direction is unlikely to be in the path of another inhabited planet" says Robert Carroll, "if you were a magical massless being who hopped aboard a photon shot from Earth in any direction, it is highly likely that you would pass through the entire universe without hitting anything larger"9.

Now, in addition to all that, Human use of radio transmissions is dwindling. Things like the Internet have replaced radio as a good default method of communication, but, do not use radio waves that might travel into space. Paul Davies, physicist at Arizona State University, states that the mass use of radio may not persist, and already we have largely moved on to use things like fibre instead. 'Moreover, many modern radio devices (such as mobile phones) rely on a technique called 'spread spectrum' encoding. It uses signals that look like background noise, except to a receiver equipped with the right unscrambling code. Us Humans figured this out within a century of inventing radio technology, so aliens might have done the same. Radio signals that are clearly artificial in origin may, then, be only a transient sign of civilisation.'12 In other words, planets harbouring intelligent life probably only emit radio waves (just like us) for a short period in their development. To be in the right spot, in the right direction, and have receivers pointing in the right direction, at exactly the right point in time, requires a bit more luck than many scientists hold out for.

One possibility considered by Paul Davies, a physicist at Arizona State University, stems from a problem that our species will face in the future: the death of our star, the Sun. Star manipulation, in order to make it last longer, or to shield it, or obtain more energy from it, could be a tell-tale sign of an ancient civilisation trying to protect itself from the star's demise.

Red giants are created when a star exhausts its supply of hydrogen at its core, with the result that the inner layer contracts and the outer layers expand, forming a redder and much larger star. If a star's outer layers could be mixed into the core, that would slow the process of inflation down. [...] Such a star would look odd, though. It would be bluer than it should be and would be of a type known to astronomers as a 'blue straggler'. [...] Perhaps, then, it will be a sign like this - of a technological civilisation millions of years old - that is seen, rather than some upstart that has not even got its radio waves under control.

The Economist (2010)13

So it might be that although SETI using radio waves is not likely to bear much fruit, it is possible to use some similar techniques but shifting the emphasis to stellar spectrography.

4. Space Travel Beyond our Solar System14

4.1. Fuel and Engine Requirements: The Biggest Obstacle

The next nearest star to Earth's Sun (Alpha Centauri) is about 4 light-years away. That might sound close, but it is actually something like 24 trillion miles away. [...] Our fastest spacecraft, Voyager, travels at about 38,500 mph (62,000 km/h). It would take about 70,000 years to get to Alpha Centauri on Voyager. [...] To get there in twenty-five years would require traveling at more than 100 million miles an hour for the entire trip. [...] The spacecraft would have to be built of some mighty fine stuff to endure such speeds for such a length of time. And there'd be no repair shops on the way. But the main problem for travel between stars is the fuel, the energy needed to get there. Estimates of the energy needed to travel to a star 4 light-years away range from one to one hundred times the total energy output of our entire planet for a year. We couldn't do it with nuclear fission because our spacecraft would have to carry thousands or millions of nuclear power plants on its wings!

"Unnatural Acts: Critical Thinking, Skepticism, and Science Exposed!" by Robert Carroll (2011)15

Some of the first thorough scientific investigations were done by the Nobel Prize physicist Edward M. Purcell (1912-1997), in the U.S. Atomic Energy Commission Report BNL-658: "Radioastronomy and Communication Through Space". Edward Purcell "was in the physics department at Harvard University, and shared in the 1952 Nobel Prize for physics. He was a pioneer in radio astronomy, the first to detect the famous 21-cm radio emission line from neutral hydrogen in the galaxy. He also is credited with the discovery of Nuclear Magnetic Resonance"16. He investigates what we might use to propel a spacecraft to almost the speed of light (c, just under 300 million meters per second), disregarding the limits of technology. So, his engines work to 100% efficiency, a feat which is impossible. In reality, heat would be wasted and build up in the spacecraft and must be expelled, etc, in ways which all reduce the efficiency of the acceleration process. Ignoring all such problems he examined what is possible if our engines are perfectly efficient. Using nuclear fusion (which is more powerful than nuclear fission), he finds:

For our vehicle we shall clearly want a propellant with a very high exhaust velocity. [...] I am going to burn hydrogen to helium with 100 percent efficiency; by means unspecified I shall throw the helium out the back with kinetic energy, as seen from the rocket, equivalent to the entire mass change. You can´t beat that, with fusion. One can easily work out the exhaust velocity; it is about 1/8 the velocity of light. The equation [...] tells us that to attain a speed 0.99c we need an initial mass which is a little over a billion times the final mass.

Purcell (1961)

This means, if your spaceship weighs an incredibly light one ton, you will need 1.6 billion tons of fuel to push it up to 99% of the speed of light. It is an astounding ratio - much of this comes from the fact that for much of the journey most of the weight you are accelerating is the weight of the fuel itself, of course, so the more and more fuel you add, in order to get to a faster speed, the less you are achieving.

Purcell, after considering nuclear fusion, reveals an even more energetic process but which is massively less likely to be accomplished: a perfect matter-antimatter propellant. Particles from this reaction actually leave the engine at around the speed of light itself, giving eight times the acceleration of nuclear fusion, and therefore achieving the maximum possible thrust that physics allows. Such engines are not even theoretically possible, but, if we could, what could we accomplish? A ratio of 7 tons of matter plus 7 tons of antimatter per ton of payload. That's much better, but, that is what is required to accelerate to the top speed. In order to ever reach an actual destination, you also have to slow down! Smashing into a star or a planet of choice and annihilating yourself is hardly what people mean by "space travel". To slow down, you need to reverse your engines and push particles out of the front of the spaceship. Because your fuel is also accelerating itself, you must square the ratio in order to slow down. You need 196 tons of fuel for each ton of spaceship. If your spaceship weighs 370kg (the weight of the International Space Station, which lacks massive engines), you'd need 73 000 kg of fuel - half of which would be antimatter (ignoring the fact that there is no source of antimatter at the scale of grams, let alone trying to get kilograms of the stuff!).

That sounds very much better. If I can somehow procure sufficient antimatter, somehow store it, and somehow control its reaction with matter, and somehow direct the resulting energy where I want it to go, I need only 7 tons of matter, and 7 tons of antimatter for each ton of payload. That sounds almost possible. But Purcell points out that all that buys you is a one-way ticket out of the galaxy: you have no way to slow down and stop when you get where you want to go. So to stop when you reach your destination requires a fuel-to-payload ratio of 196. And if you want to someday return, unless you know of a convenient matter-antimatter fueling station at your destination, you will need to square that again, for a fuel-to-mass ration of almost 40,000.

Purcell (1961)

Sebastian von Hoerner in "The General Limits of Space Travel" (1962) covers much of the same ground (including some other methods such as fuel scoops), but his mathematics and equations unfortunately lead him to come to some of the same conclusions as Purcell:

After several pages of equations covering much the same ground as Purcell, Von Hoerner concludes, "there is no way of avoiding these demands [for power], and definitely no hope of fulfilling them... space travel, even in the most distant future, will be confined completely to our own planetary system, and a similar conclusion will hold for any other civilization, no matter how advanced it may be".

Von Hoerner (1962) quoted by Shaeffer (2012)

Return journeys are out of the question, even with perfect matter-antimatter engines, perfect navigation and miraculously deep sources of antimatter.

4.2. Trying to Avoid Frying the Earth

In order to achieve the required acceleration our rocket, near the beginning of its journey will have to radiate about 1018 watts. This is a little more than the total power the earth receives from the sun. But this isn't sunshine, it's gamma rays. So the problem is not to shield the payload, the problem is to shield the earth.

Purcell (1961)

The perfectly efficient high-propulsion engines we have been considering make space travel possible in terms of the speeds that could be achieved. The fuel to payload ratio only worked with a matter-antimatter engine pushing out high-energy gamma rays at the speed of light, out of the engine. And what is behind the engine? The Earth. The Earth does not receive that level of radiation from the sun; our spaceship would fry the Earth in a serious way. At such high accelerations, the ability to "steer" the spaceship so it doesn't point its engines at the Earth would tear the ship apart. Even if it departed from the moon in order to avoid frying the Earth and to gain an advantage against gravity, it would fry the moon and start irradiating it (causing problems for one of the greatest assets we have when it comes to space travel). And even if it does depart from the moon, once the spaceship is a short distance away (in interstellar terms) the cone of radiation behind will soon cover both of them anyway. No matter which way it points at initial takeoff, it will fry its source location.

We'd have to launch the spaceship and let it sit there for a few months until the Earth had moved away, keeping the spaceship travelling at ordinary speeds, and then turn it, and fire up its engines, taking care to turn the engines off at intervals when the Earth is approaching the arc in its orbit where it is behind the spaceship's cone of radiation. Such fiddly and time-consuming procedures would also have to be employed at the destination if the spaceship is to follow a return journey (assuming there is something of worth at the destination that we want to avoid destroying). Luckily such manoeuvering, at low speeds, requires much less acceleration and therefore doesn't add much more fuel. It does add a lot of time manoeuvering in the local solar system before the journey can safely begin, and a similar amount of time at the destination. As the timescales involved tend to dwarf human lifespans, the entire process has to be automated so that us humans can sleep, or, as per standard science fiction fare, the crew remain mostly asleep except for one or two awake at a time in order to monitor progress. But let's not even start considering the obstacles thrown up by the requirements of cryogenic sleep and constant thawing and freezing of the poor crew!

4.3. The Requirements of Front Shielding

Shaeffer summarizes Purcell's excellent article on the realities of space travel at high portions of the speed of light where he points out that the stray particles you still get in deep space pose a great problem:

And even if you could somehow construct such a vehicle, your problems are not over. If you are moving with 99 per cent the velocity of light through our galaxy, which contains one hydrogen atom per cubic centimeter even in the "empty spaces," each of these hydrogen atoms looks to you like a 6-billion-volt proton, and they are coming at you with a current which is roughly equivalent to 300 cosmotrons per square meter. So you have a minor shielding problem to get over before you start working on the shielding problem connected with the rocket engine.

Shaeffer (2012) quoting Purcell (1961)

We could use things like massive generated magnetic fields to try to shield the spaceship from charged particles, if we can push these fields forward enough that they shield the spaceship effectively at such massive speeds. Such shielding is not really theoretically possible but even if it was, all of this draws away power from the engine. If you push a field forwards, you are reducing the acceleration of the ship, increasing the fuel to payload ratio. As we can't actually construct this type of shielding we don't know how much energy it would require (a lot), therefore we don't know just how catastrophic its impact would be on fuel requirements.

4.4. Non-Euclidean Travel

Worm-holes, teleportation, multiple-dimensional space-bending engines, warp engines and other elements of science fiction often base themselves on some elements of truth, often from the strange world of quantum physics, but sometimes, purely from the imagination. Of these, the wormhole is probably the most scientifically studied and our understanding of wormholes, if they exist, comes mostly from our understanding of black holes. Black holes have massive impacts over large areas, and, worm-holes are in the same category of stellar object. The problem is, there is no direct or indirect evidence that they actually exist.

...their actual existence is frankly extremely dubious. There is no reason to think that they could occur naturally, and no observational evidence that they actually do exist (unlike Black Holes). Even if they do exist, they may exist only on the Planck scale (subatomic quantum size). [...] There is also the problem of simply getting to the wormhole's mouth. If a wormhole were near our solar system, we would already detect its disturbing effects of warped space. And if it is far from our solar system, we need to develop interstellar travel simply to travel to the wormhole's mouth!

Can we create a wormhole to go from where we are to where we want to be? Perhaps in theory we might, but the reality of a recipe for creating a wormhole will undoubtedly be something like this:

Take 100 solar masses. Bake at one million degrees for ten thousand years. Stir in 100 solar masses of exotic matter with negative energy density. Stretch out the mix from desired source to destination. Let cool for one million years.

So the idea of using wormholes as a convenient transportation network to wherever in the universe we want to go is, well, fanciful and implausible in the extreme. We can't proclaim it completely impossible, but the person who proclaims it as a reality had better have extraordinarily good evidence that such a thing exists.

Shaeffer (2012)

4.5. Summary (and more problems)

If we don't attempt to reach speeds that are a sizable portion of the speed of light, more is possible. At 0.1 of the speed of light, which could be technologically possible in the far future, it will take hundreds of years to approach the nearest stars. So we are talking of gigantic spaceships complete with life support and everything else required to support multiple generations of humans. Not because we are assuming they're awake for the whole journey, but, because they certainly will be awake at the destination, and with such a huge spaceship, it is certainly a one-way journey. They need to take everything with them, from living modules, to a complete life's worth of scientific equipment, living quarters, engineering tools, educational facilities, etc. The more you take, the more mass you have to accelerate, and the more fuel you need to take.

The construction of such an ark is unprecedented and although we'll certainly gain experience with lunar and Martian missions, it is an incredible expenditure of materials, money and time (and human lives), just to reach the nearest stars in a dead-end one-way journey. Once there, the chances of refuelling are non-existent, meaning, any further supplies and personnel must be summoned and themselves travel for a few hundred years. Although possible these endeavour are not actually practical, at least not for the foreseeable future.

5. The Impact on Religion of Discovering Intelligent Alien Life

5.1. Can Species-Specific Religions Claim to Embody Ultimate Truth?

When we discover intelligent life in the universe we will have to face certain facts. The first would be that the appearance of an intelligent humankind was not a special act of creation by god(s). If intelligent life can arise in a multitude of conditions it makes it less arguable that God needed to act specially in order to create humankind. Yet such actions are part of the creation stories of all major religions. The particulars of our religions would be reduced to local symbolism and relative truths that apply only in some parts of the Universe, to some species.

If one group of sentient beings on Planet A have to abide by a religious book that was sent their way by a divine messenger, and sentient beings on Planet B have a different book, in a different language, with completely different stories of creation, sin and redemption, then how do adherents on either planet claim that their religion is the ultimate truth? It can't be the ultimate truth. It is only localized, temporary, limited truth, which applied only to one species, for the duration of their existence. I am sure that just like all human religions, part of the lore includes masses culture-specific, language-specific and time-specific texts that lose meaning over distance and time. If those two vastly different cultures meet on Planet C, then, by which ultimate truth would the future natives have to abide by? Clearly, new religions would be needed to cope with these complexities.

Imagine an intelligent race in the universe finding out what our religion says about us and our central position in the Creator's plan, and perhaps imagine trying to tell them that our religions are not born from our own imagination, pride and ego! Needless to say, we would embarrass ourselves.

5.2. Saviour Religions Will be Challenged

The impact of extra-terrestrial life on theology is a lot more interesting than outsiders would presume. The existence of aliens therefore throws a long shadow of doubt over the entire Christian system of sin and redemption, Heaven and hell, and in particular, cause problems for the idea of an only-son-of-god saviour. Judaism, Christianity and Islam all have holy books that claim to be absolute truth, yet, their cosmology places humankind and the Earth in a special, unique position in God's plan especially with regards to the causes and solutions to suffering. When we find aliens and discover their religions, if they have them, our traditional religions will no longer make much sense.

In Christianity the Creator of the Universe has only one son, and that one son was born on Earth in the form of a Human, and died there in order to save humans (1 Peter 3:18). Such a sacrifice only occurred once - not once per planet, once per intelligent species, or even once per galaxy. There is no saviour for anyone who isn't on Earth. Aside from the Creator of the Universe having a human son, but Humans were created in the image of God and the angels, together in Genesis 1:26-27 they say "Let us make man in our image, in our likeness, and let them rule over the fish of the sea and the birds of the air, over the livestock, over all the earth, and over all the creatures that move along the ground". This special creation of humankind must distinguish us from any race of intelligent aliens, who obviously only merely evolved into greatness. And in Biblical eschatology, when evil and suffering is stopped in the whole of creation, where does God place his new paradise? On Earth, of course (Revelations 21)! That's quite an endorsement of our species, from the creator of a billion billion stars!

Is it amazing divine grace that us Humans are so blessed with the Creator's special and ultimate attention? Or is it an anachronism, written into our myths and religions during a time when Humanity did not yet perceive the vastness of the Universe? Given that Christianity fought major battles with astronomers about the Earth being the center of the world and with biologists about evolution, and lost both major battles, I would hazard a guess that when it comes to the uniqueness of the Human race in the Universe, Christianity also finds itself the wrong side of the divide between mythology and history.

The Christian conception of God, sin and salvation, and of the son of God, Jesus Christ, is steeped in egotistical and prideful homocentricity.

"Homocentricity or Anthropocentrism: Why Do Religions Think Humanity Is Central to God and Creation?: 1.2. Homocentricity in Christianity" by Vexen Crabtree (2003)

In Christian theology Adam and Eve were punished for the original sin (of eating the apple); this punishment would be passed on from parent to child, and included not only suffering in general and death, but also many specifics, such as having a painful childbirth. Romans 5:12: "Therefore, just as sin entered the world through one man, and death through sin, and in this way death came to all men, because all sinned". Humankind was also expelled from the Garden of Eden at that point. Clearly, aliens on another planet are not subject to original sin, and, the punishments listed in the Bible may not even be applicable for the various possible life forms which exist in the Universe. Jesus was god's only son, crucified once here on earth, for us humans. Alien life makes a mess for the entire Christian idea of sin and salvation.

"The Crucifixion Facade: 5. Extra-Terrestrial Alien Life and Salvation" by Vexen Crabtree (2002)

Book CoverMaking our Earth just one amongst many raised thorny questions about Christ's uniqueness. It was hard to reconcile multiple inhabited worlds with the fundamental tenet of Christianity, that God singled out the human race for special attention.

"Science: A Four Thousand Year History" by Patricia Fara (2009)17The existence of extra-terrestrial intelligence would have a profound impact on religion, shattering completely the traditional perspective of God's special relationship with man. The difficulties are particularly acute for Christianity, which postulates that Jesus Christ was God incarnate whose mission was to provide salvation for man on Earth. The prospect of a host of 'alien Christs' systematically visiting every inhabited planet in the physical form of the local creatures has a rather absurd aspect. Yet how otherwise are the aliens to be saved?

"God And The New Physics" by Paul Davies (1984)18

Although Paul Davies talks of the humorous idea of thousands of Christs resembling various aliens, being sent to all those planets by God, it contradicts the main messages of the Bible: that Jesus was God's only son and that the Crucifixion was a unique event specific to Jesus (1 Peter 3:18). So, there is no salvation for aliens. Also, Biblical eschatology has Zion descend on to Earth after Judgement (Revelations 10), with no more stars in the sky. Genesis 1:26 says that man is made in the 'image' of God and the angels, 'in our likeness'; so where would aliens come from? Are we to believe that intelligent life evolved throughout the universe but that our species in particular was created by the Creator, and that the Creator happens to look Human, along with the 'only' son of God who is also Human-shaped? To believe such things is known as 'homocentricity', a prideful and egotistical speciesism. Do aliens who live countless light-years away from Earth really have to know Jesus in order to be saved? But if you alter the Bible's stories to make them compatible with alien races on other planets, you also alter the central truths of Christianity; the religion you end up with after taking aliens into considering simply isn't Christianity any more.

"The Crucifixion Facade: Extra-Terrestrial Alien Life and Salvation" by Vexen Crabtree (2002)

Some activist Christians have pushed for Christian messages to be sent out into space, and that our first priority should be to convert aliens. The horrendous consequences of this type of belief when Christians conquered the natives of Northern America and Australia are written into our history: They converted, or were killed. Hopefully such a violent and shocking confrontation will not also be part of humanity's future.

5.3. Universalist Religions

Mainstream theologians and intellectuals within the Abrahamic suite of religion have not given much time to discussions of the implications of alien life. However some have, and Erman McMullin warns his fellows that "religion which is unable to find a place for extraterrestrial persons in its view of the relations between God and the universe could find it increasingly difficult to command man's assent in times to come"18.

Some saviour religions actually cater for aliens. The Urantia movement holds that God has 700 000 sons incarnated on various worlds in the universe; Jesus is, of course, one of those divine sons19. The early scientist and astronomer Huygens argued that "the planets must be inhabited because otherwise God had made worlds for nothing"20. The religions that seem best placed to function in a Universe with more than species of intelligent, sentient beings are those that hold to universalist ideals; that is - the creator of the universe saves all living beings, and everyone goes to heaven. Other positions - that God punishes members of one species for doing 'evil' things, while punishing members of a different species for doing completely different things according to local circumstances, does not make sense if God embodies any set of absolute morality. In other words - deist, pantheist, universalist and non-religious forms of deism appear to be able to explain aliens much better than Abrahamic religions (Judaism, Christianity and Islam).

5.4. There are Already Alien-Centered Religions21

There have also been many sects, cults, and schools of thought, religious or not, that have been atheist. For example many UFO cults are atheistic. The Raelians were founded by Mr Vorilhon when fluent French-speaking aliens told him that we had mistranslated the Bible, and in fact everything on Earth was built by the aliens. The infamous Scientology is a sci-fi, self-help, anti-alien religion with beliefs that don't include any kind of theism (hence, it is also atheist).

"Atheism and Secularism: 3. Atheist Religions" by Vexen Crabtree (2013)

Read / Write LJ Comments

By Vexen Crabtree 2014 Mar 23
Originally published in 1999
Parent page: Life and Death

Social Media

References: (What's this?)

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The Bible (NIV). The NIV is the best translation for accuracy whilst maintaining readability. Multiple authors, a compendium of multiple previously published books. I prefer to take quotes from the NIV but where I quote the Bible en masse I must quote from the KJV because it is not copyrighted, whilst the NIV is. [Book Review]

The Economist. Published by The Economist Group, Ltd. A weekly newspaper in magazine format, famed for its accuracy, wide scope and intelligent content. See for some commentary on this source.

The Guardian. Respectable and generally well researched UK broadsheet newspaper.

Carroll, Robert. Taught philosophy at Sacramento City College from 1977 until retirement in 2007. Created The Skeptic's Dictionary in 1994.
(2011) Unnatural Acts: Critical Thinking, Skepticism, and Science Exposed!. Kindle edition. Published by the James Randi Educational Foundation.

Clarke, Peter B.. Peter B. Clarke: Professor Emeritus of the History and Sociology of Religion, King's College, University of London, and currently Professor in the Faculty of Theology, University of Oxford, UK.
(2011) The Oxford Handbook of The Sociology of Religion. Published by Oxford University Press, Oxford, UK. First published 2009.

Davies, Paul
(1984) God And The New Physics. Penguin 2006 edition. Davies is a Professor in theoretical physics who has published ground-breaking research.

Dawkins, Prof. Richard
(2006) The God Delusion. Hardback. Published by Bantam Press, Transworld Publishers, Uxbridge Road, London, UK.

Dawson, Lorne L.. Professor of Sociology and Religious Studies at the University of Waterloo, Ontario, Canada.
(2011) Church-Sect-Cult: Constructing Typologies of Religious Groups. This essay is chapter 29 of "The Oxford Handbook of The Sociology of Religion" by Peter B. Clarke (2011) (pages p525-544).

Fara, Patricia
(2009) Science: A Four Thousand Year History. Hardback. Fara has a PhD in History of Science from London University. Published by Oxford University Press.

Gardner, Martin. Died 2010 May 22 aged 95.
(1957) Fads & Fallacies in the Name of Science. Published by Dover Publications, Inc., New York, USA. Originally published by G. P. Putnam's Sons in 1952 as "In the Name of Science".

Hoerner, Sebastian von.
(1962) "The General Limits of Space Travel" in Science 137, 18, 1962. Reprinted in Cameron, Interstellar Communication. New York: W.A. Benjamin, Inc., 1963. Summarized in Sheaffer (2012).

Purcell, Edward M.
(1961) "Radioastronomy and Communication Through Space", U.S. Atomic Energy Commission Report BNL-658. Reprinted in Cameron, A.G.W. (editor), Interstellar Communication. New York: W.A. Benjamin, Inc., 1963. Summarized in Sheaffer (2012).

Sagan, Carl
(1995) Cosmos. Originally published 1981 by McDonald & Co. This edition published by Abacus.

Sheaffer, Robert.
(2012) Blog post Is Interstellar Travel "Preposterous"? (2012 Dec 29) on Printed in Skeptical Inquirer (2013 May/Jun) p24-26.


  1. Fara (2009) p128. Added to this page on 2010 Jul 01.^
  2. The Guardian (2005 Aug 25) G2 insert. Provides the comments on Epicurus.^
  3. Dawkins (2006) p137-8, 69-70.^
  4. Fara (2009) p339. Added to this page on 2011 Feb 14.^
  5. The Economist (2008 Mar 29) obituary of Arthur C. Clarke.^
  6. Skeptical Inquirer (2008 Jan/Feb) Vol.32 No.1 p11 article "Exciting UFOs Become Bland IFOs".^^
  7. Erich Goode "The Skeptic Meets the Moral Panic" in Skeptical Inquirer (2008 Nov/Dec) Vol. 32 Issue 6. Goode has taught sociology at multiple USA universities and has authored multiple books on sociology, including co-authoring the book Moral Panics.^
  8. Gardner (1957) chapter 5.^^
  9. Carroll (2011) p231-232. Added to this page on 2014 Mar 22.^^
  10. Kenneth W. Krause in Skeptical Inquirer (2007 Nov/Dec) issue p57. K. Krause is a former prosecutor and criminal defense attorney with degrees in law, history, literature and fine art.^
  11. Added to this page on 2012 Oct 17.^
  12. The Economist (2010 Apr 17) article "Cosmic archaeology". Added to this page on 2012 Oct 17.^
  13. The Economist (2010 Apr 17) article "Cosmic archaeology". Added to this page on 2014 Mar 22.^
  14. Added to this page on 2014 Mar 23.^
  15. Carroll (2011) p231-232.^
  16. Sheaffer (2012).^
  17. Fara (2009) p128.^
  18. Davies (1984) p71. Added to this page on 2010 Jul 19.^^
  19. Dawson (2011) p370.^
  20. Sagan (1995) p170.^
  21. Added to this page on 2013 Jul 25.^

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