One of the most daunting tasks in both space travel and speculation merges the two in trying to accurately describe what an alien race would be like if we actually did meet them – explaining their complex system of travel as well as their ability to survive the long journey that would last years between the stars. And as our understanding of the scale of the universe around us becomes more concrete, so have the channels through which potential alien visitors have been described. And in doing, three different theoretical types of alien visitors have arisen that humanity may do well to avoid contacting.
The three all come from the perplexing Fermi paradox that suggests the universe may be more hostile to advanced alien cultures than we once thought. It suggests that if life were plentiful in the universe, it would be impossible to cover up as new races would be visiting daily in their faster than light spacecraft or contacting us indirectly via radio communication. And the very thing that inspired the Fermi Paradox is the first type of alien machination that humanity may want to stay away from – the Von Newmann Probe.
The Von Newmann Probe isn’t a problem in itself. If humanity were to encounter a mysterious self replicating device with an incredibly well programmed mission and the most basic understanding of how to keep itself running without endangering any biological entities it encountered, then we might very well want to eventually be visited by one as we reached into the stars. But just like regular cells divide complex information again and again, it may be theoretically possible for the Von Newmann probes to become corrupted somehow and begin dividing out of control – using up any available resources they came across as material for further probes. If this were the case, then we may very well have a very slow but a sort of galactic apocalypse on our hands – or at least an incalculably large army of once benign drones growing out of control.
But what if the probes weren’t designed to spread throughout the universe gradually collecting information and reporting back at a snail’s pace? What if instead they were sent out as automated terraforming factories designed to take dead worlds and transform them gradually into living ones using the components within and then build more terraforming probes once the device had completed its mission? This seems like a fairly noble idea except for one problem – different species may require different environmental conditions to survive. One alien species’ paradise may be another’s personal vision of hell. Eventually as the universe was converted into a place ideal for one type of species, it would edge all others out. David Brin’s 1986 short story collection “The River of Time” explores the idea of these “seeder ships” and their interactions with one another – ultimately creating an ecosystem in itself.
Finally of course there is the most terrifying of the theoretical drones – the self replicating doomsday drones. They are essentially the same as the malfunctioning “cancerous” Von Neumann probe, but with one variation – they were designed to be that way.