By Seth Shostak
Senior Astronomer, SETI Institute
As spring eases into summer, the multiplexes are witnessing an all-out alien assault. Within the space of a month, silver screens have shown ships of the U.S. Navy belching ordnance at invading extraterrestrials in Battleship; portrayed black-garbed government agents keeping tabs on ornery aliens in Men in Black III; and are promising the long-awaited back-story of perhaps the most visceral space opera of all time (Alien) in Prometheus.
These fictional tales appeal to us with themes that are long established: The all-powerful enemy with some niche vulnerability that humankind can discover and exploit; the potentially malevolent neighbors who are not what they seem; and the odd strangers who lie in wait, keen to turn us into surrogate mothers thanks to unauthorized breeding experiments.
Extraterrestrial beings offer obvious benefits for the movies' creators. The filmmakers can exploit the possibilities of novel settings and situations, and can fashion their antagonists to be thoroughly repugnant and in possession of technology that would stun DARPA.
Obviously, there is no pretense that Hollywood aliens might accurately reflect actual inhabitants of the galaxy. But is it all just free-form imagination? Can contemporary science say much about whether these cinematic sentients might be ciphers for the real thing?
That may sound like an unanswerable question. After all, researchers haven't yet found any life -- dead or alive -- from beyond Earth. None; not even microscopic life. That fact seems to gives the moviemakers utterly free rein. But not entirely. We know a few things about both astronomy and biology that can help delineate what's plausible when it comes to extraterrestrials.
One thing that every school kid learns is that the distances between stars are vast. This, of course, is a challenge to rocketry -- our fastest spacecraft would take 100 thousand years to travel to even the nearest star. But it's no real impediment to filmic aliens, as they can be presumed to be far beyond our own technical level. After all, they've demonstrated their advanced technology by coming here, for good or otherwise (or, as in the case of Alien, have invaded someone else's world.) Clearly, this automatically implies that any weaponry these visitors wield will also be far beyond the capabilities of our own quaint arsenals. It's not likely that we could really take them on and win. However, if Hollywood were to bow to that fact, it would turn most alien invasion films into short subjects.
The large distances between the stars will also affect the motivation for any extraterrestrials to come to Earth. In some sci-fi, the visitors from afar have opted to visit because they are aggrieved by our nuclear weaponry or our poor treatment of the environment. But our cosmic confreres won't know about either, since the radio and television broadcasts (or for that matter, the reflected light from the greenhouse gasses in our atmosphere) will not yet have reached their world, and alerted them to our bad behavior.
Often, invading aliens decide to drop by because we have some tempting natural resources. Water is a favorite, but so are heavy metals. However, one of the great triumphs of astronomy has been to show that the entire cosmos is composed of the same stuff everywhere. The aliens can find needed raw materials at home, and save the transportation costs.
Most movie aliens also share our body plan -- an upright stance with two arms, two legs, and a nose separating eyes and mouth. Their biochemistry is often similar enough to ours that they can either get some nourishment by eating us, or use us for breeding -- all of which would be remarkable, which is to say unexpected and unlikely. But the movie mavens know that if the aliens are too alien, audiences will have a difficult time reading their intentions, or accepting any interaction between them and us.
The bottom line is that Hollywood aliens are mostly reflections of ourselves, and hardly accurate ciphers for real extraterrestrials.
Even so, sci-fi movies are more than just entertainment: they are remarkably influential in getting young people interested in space and science in general. This is not because these pictures correctly reflect what we know about the universe, but because they are emotionally compelling. The facts might be wrong, but the story telling grabs young minds, and infuses the subject matter with romantic appeal.
The National Academy of Sciences has recognized the significant influence of cinema sci-fi on youth, and has inaugurated a program, known as the Science and Entertainment Exchange, that brings practicing scientists and filmmakers together. That way, not only will Tinsel Town script writers be able to sharpen the fidelity of their product, but they'll also hear of discoveries that might help in the development of novel story concepts.
And that could be beneficial to all concerned because, after all, the hero of a sci-fi story is not a character -- it's the idea.