Carina Nebula (courtesy NASA). Click to enlarge

Does anyone recall the scene in the movie “Independence Day”, when Will Smith discovered an alien spacecraft that worked and behaved exactly like a modern fighter jet? Perhaps you remember the scene in Star Wars where aircraft marshallers, used internationally recognised signals to bring the rebel craft to a halt? Clichés dominate most blockbuster science-fiction. How many times have we seen cargo ramps, flashing lights, handheld heat sensors and all the other standard accoutrements of “alien” technology? How many times have aliens been depicted as immature humanoids with long arms, wide eyes and oversized heads? The recent movie Avatar*, portrays alien creatures so similar to us they would easily beat our close genetic cousins, the chimpanzees, into a distant second place. All of this indicates that we have very limited set of ideas of what aliens might really look like.

To understand what alien contact might resemble, it is worth considering the cargo cults that popped up in the more remote regions of the South Pacific during the 1940’s. American servicemen landed on the islands in order to create airfields to help in the war effort. The local tribespeople had never before encountered modern civilisation. They were thus hurled from the stone age to the 21st Century in a matter of moments. They had no language to describe guns, airplanes, bombs and helicopters, chocolate, radios or uniforms. Long after the airmen left, the natives would cut out clearings, set up mock landing strips out of wood and whatever material they could muster, in order to usher back the sky gods who provided them with all this weird and wonderful cargo.

It is likely therefore that no words in any language could properly describe a real alien visitation. We would be dealing with something beyond the limits of our imagination. A thousand assumptions about extraterrestrials would be blown away instantly. This would be especially the case if we were dealing with a civilization thousands, even millions, of years more advanced than us.

The likelihood of aliens looking anything like us is, in my opinion, vanishingly small. We humans are products of planet Earth: its dynamics, its chemical processes, its biology and its history. It’s important to realise this when considering the possible differences between Earth and an alien world. There would be differences in temperatures and temperature ranges, ages, rotational periods, revolutionary periods, planet sizes, atmospheric compositions, atmospheric pressures, solar strengths, orbital eccentricities, axial inclinations and wind speeds, to name but a few factors. Complicating this even further would be the biological systems on another living planet. Different lifeforms would compete remorselessly, creating a diversity of biological forms that would be perfectly matched to niches suitable to their home planet’s environment. Other elements such as the frequency of mass-extinctions or climate change events would also drive the eventual form of life on this planet.

The resulting differences might be enormous. Our alien counterparts could be kilometers wide or smaller than a mite. They might live their lives over a period of millennia or merely a few seconds.  The alien “mind” might be a single entity, or distributed across multiple independent units. Emotions might not exist. Language might not exist. Empathy might not exist. Consciousness might exist on a completely different level to our own. They might be receptive to a completely different part of the electromagnetic spectrum – infrared, ultraviolet or radio waves. Suffice to say that Star Trek, with it’s bumpy headed, American accented aliens, is not the template we should choose.

Of course there are people who believe that intelligent life would, by necessity, converge on the human form. Processes such as convergent evolution might drive creatures to behave and look similarly to creatures on our planet. Others would say that intelligent life could only possibly exist on a world almost identical to our own. These are possibilities certainly, but my feelings are that, in order to thrive, life does not require perfection, just sufficient conditions for survival. After that it’s anyone’s guess what the path of development might be.

So we are left with a real conundrum. There may not be intelligent aliens out there at all, but if there were and if they were capable of making their way across the vast distances between the stars to meet us, it may not be possible to relate to them in any practical way. If SETI ever discovers anomalous signals, or if they show up unannounced on our front door some day, we are in for quite a treat, but it’s unlikely we will understand them when they ask us to take them to our leader.

* To be fair to James Cameron, making his creatures humanoid was deliberate. Falling in love with a jellyfish like creature** does not, after all, make for great cinema.

** I know, I know. Galaxy Quest. Shhh!