If we find life on Mars — we are doomed!

Can you guess why finding alien life on our neighbouring planet could spell the long-term extinction of Humanity? A thought experiment.

Recently I did what every reasonably intelligent, inquisitive person should do: I downloaded a bunch of files from the Sam Harris Making Sense Podcast page and stored them on a micro-SD card. This I inserted into my car radio, and now, while driving, I listen to very sensible discussions instead of news repeats and weather reports. You should try it — there is an endless supply of material on Sam’s podcast page.

One discussion I listened to — twice in fact — was with Nick Bostrom, a Swedish-born Professor at Oxford University who specialises in theoretical physics, neuroscience, logic, and, most significantly (for me), artificial intelligence. I have read a number of his books, and he has influenced my thinking profoundly.

In the Sam Harris podcast Bostrom (and Sam) came up with a cosmological idea that was new to me. I have used it to formulate the puzzle given in the headline above.

The question why finding life on Mars, which is what the current generation of rovers is trying to do, would possibly mean that humanity is doomed — this question generally leads to scepticism. “You mean if we bring some deadly alien lifeforms back to Earth?” people ask. No, if we simply find any form of alien life, even bacteria or lichen like creatures, even if we leave them where they are. In fact finding ancient fossilized shells or bacteria would spell doom. “So just the fact that we discover life on Mars means we are doomed??” people ask, and challenged me to describe any train of thought that could possibly lead to this conclusion.

The reasoning for the dire conclusion is based on two ideas which I need to explain before I tell you the why we might be doomed.

Bostrom’s “urn metaphor”

The historical process of science and technological discovery can, according to Bostrom, be pictured as a giant urn which contains a large number of white balls, but also a few grey and a few black ones. People are reaching into the urn all the time, and pulling out (white) balls, each of which provides a deeper understanding of the world. They pull out a ball that allows them to construct steam engines, one that leads to the general introduction of electricity, one to the invention of wireless communication, etc. etc. The white ball advances are generally beneficial, to the inventor and to human society. There may be some disadvantages, but usually these can be controlled and they do not result in mass destruction.

Pulling out a grey ball leads to the development of more dangerous technologies which can lead to serious destruction, even to the end of civilisation. Atomic energy is a good example: it can be used to generate vast amounts of electrical power, but it also allows the construction of fission and fusion bombs with devastating strength, potentially enough to wipe out civilisation as we know it.

So why did grey ball of atomic understanding, and other grey balls we have pulled out of the urn, not lead to disaster? There is a simple reason: the technologies required for the production of massively destructive weapons are very hard to master. They require the cooperation of a large number of scientists and the backing of nation states. Imagine if the atomic ball had shown us how to make a nuclear device by baking sand in a microwave oven (Bostrom’s example), or if it took just a skilled engineer a few months to build a megaton bomb using easily available devices and materials. That would have meant the end of cities and civilised areas. If, of the seven billion people living on the surface of the earth, one millionth of one percent has genocidal or suicidal inclinations, then the ability to execute mass destruction very easily would mean that society, as we know it, would cease to exist. We are simply lucky that it turned out to be so hard.

So what is a black ball? It is, in Bostrom’s definition, a discovery that will lead to the end of civilisation by default. This could be through the deployment of the new technology by mal-intentioned agents, or through consequences that we fail to anticipate (or can do nothing about). A short-term example could be the development of easily accessible genetic manipulation. Imagine if we developed a 3d-printer like device that could produce DNA sequences using a PDF file you can download on the Internet. Imagine that a few very evil-intentioned scientist formulated the code to create the deadliest form of viruses and bacteria ever seen. That would give them powers of destruction that are even greater than thermonuclear weapons, which only destroy individual cities. Weaponised biological agents can rapidly spread over entire countries.

So we must consider ourselves extremely lucky that we have, so far, only pulled out white and a few grey balls out of the urn. And we can hope (without any justification for doing so) that no black ball exists.

But let us assume there is a black ball, one that any civilisation will sooner or later pull out of the urn. It could be far deadlier than the example described above and inevitably lead to the destruction of any civilisation that chanced upon it. The consequences of pulling out the black ball would not be restricted to our planet or our civilisation — it would have the same effect everywhere, since the ball is about the understanding of physics and reality, which is the same all over the universe. That has serious consequences.

Next step: Fermi

You probably know Fermi’s famous paradox. Put briefly, it asks why Earth is not teeming with alien lifeforms. There are about a trillion planets just in our galaxy, and many have existed for a number of billions of years. It is reasonable to assume that some will have developed life that evolved to technically advanced civilisations.

And now to the critical point: human society on Earth, which is one example of such an evolution, can be reasonably expected to undertake interstellar exploration within the next few centuries. If no faster-than-light travel is discovered, and we use our biological bodies to undertake the journeys, how long would it take to colonise the entire galaxy?

Let us assume it takes a couple of thousand years for Earth-based explorers to reach five neighbouring life-sustaining star systems, and it takes a thousand years for each of the colonies to advance to a stage where they can in turn send out starships for further exploration. Remember, they don’t need to invent the technology from scratch, just develop economic conditions that makes further interstellar exploration possible and desirable.

In this case, after a few thousand years, we will see twenty-five spaceships setting out to other planets. Geometric progression tells us how it will continue: at this rate of exploration humans would be able to colonise the entire galaxy, all the millions of habitable planets, in just 20 to 40 million years. And this is the most conservative scenario — flesh-based beings using generation ships. Self-assembling robot systems could do it much faster.

A few tens of millions of years are the blink of an eye in cosmological terms. If dinosaurs had advanced to space travel the Milky Way would now be completely colonised by those creatures. That means that it should certainly have happened for a different civilisation, or for hundreds of advanced societies, a long time ago. Remember that we are the youngest technological species in the galaxy (Homo Sapiens developed science and engineering in the last three or four thousand years — it makes no sense to assume that there are civilisations out there that are even more recent). No, other civilisations should be on average a giga-year older, which gives them ample time to colonise the galaxy many times over.

So why aren’t they here, why have we not found a shred of evidence that Earth has ever had alien visitors in the past? Or even detected any signals that indicate that there is advanced life in distant star systems?

The Great Filter

There have been a number of attempts to solve the Fermi Paradox. One of the more reasonable explanations, put forth by Robin Hanson and others, tries to explain why we haven’t found alien life. Of all the planets in the Milky Way that support self-replicating life forms, a large number of them should have evolved into advanced technological civilisations; and many of these should have undertaken interstellar exploration; and all this should have happened millions of years ago. Yet in fact, when looking deep into Space, all we can detect is lifeless matter

Hanson says that the reason why we have seen no evidence that any civilisation or have visited our solar system might be the existence of a “Great Filter,” something that prevents pure matter throughout the universe from giving rise to expanding civilisations that develop to a point where they can be seen by other civilisations, or in fact travel to them. A link to a talk he has given on the subject is to be found at the end of this section.

So there could be something that reliably prevents advanced civilisations from developing, and from becoming visible. That Great Filter, when considering our own civilisation, could lie in the past or in the future. If it lies in our future it is most likely to be a black ball extracted from the urn, one that everywhere in the universe inevitably destroys civilisation.

If it lies in the past, i.e. the filter prevents life from developing to the stage that we have reached, then it means that we might be the one incredibly rare cases which slipped through the filter. And here the most likely point where this could have happened is in the origination of life itself. Say the chances of life starting anywhere in the universe, the chance of random molecules bumping into each other in such a way as to form self-replicators, was one in 10⁵⁰ or less. That could actually mean that we are indeed alone in our galaxy, or in fact in the universe — the result of an unimaginably rare occurrence.

You notice that we have arrived at the answer to the question I asked at the outset. If we discover truly alien life on Mars, even if it is very primitive, that is bad news for mankind. It means that life has been able to start in two places in a single star system, which in turn means that it has to have happened on countless planets, and the galaxy and the universe must be teeming with life. Conclusio: there must be millions of life-harbouring planets in the Milky Way, with thousands of advanced civilisations amongst them.

Now that appears not to be the case, which leads us to conclude that the Great Filter is not behind us, in our biological history, but ahead of us in our future technological and social development. And that it is something that inevitably occurs, reliably preventing any civilisation from achieving interplanetary travel and colonising the galaxy. Most likely they all, every one of them, pull a black ball out of the urn and perish at some stage, just as we will, at a time that is not so far in our future.

Summary by Robin Hanson (on TEDx)

The universe is vast, dark, cold, empty — and dead. Everywhere we’ve ever looked, outside of Earth, it is all … completely … dead. If you saw aliens out there you might be scared of them. But you should be more scared if you see no aliens, if you see absolutely nothing. Because, likely, something out there is killing everything — and you’re next! … The point is we have never seen [any sign of life]. All we’ve ever seen is lots of dead matter. That should scare you!

Frederic Alois Friedel, born in 1945, science journalist, co-founder of ChessBase, studied Philosophy and Linguistics at the University of Hamburg and Oxford.