First there was the Wabbler, the charmingly antropomorphized naval mine of Murray Leinster‘s 1942 science fiction story of the same name. The Wabbler was a mechanical device whose destiny whose nature the reader only gradually discovered as the narrative progressed.
The Wabbler went westward, with a dozen of its fellows, by night and in the belly of a sleek, swift-flying thing. There were no lights anywhere save the stars overhead. There was a sustained, furious roaring noise, which was the sound the sleek thing made in flying. The Wabbler lay in its place, with its ten-foot tail coiled neatly above its lower end, and waited with a sort of deadly patience for the accomplishment of its destiny. It and all its brothers were pear-shaped, with absurdly huge and blunt-ended horns, and with small round holes where eyes might have been, and shielded vents where they might have had mouths. The looked chinless, somehow. They also looked alive, and inhuman, and filled with a sort of passionless hate. They seemed like bodiless demons out of some metallic hell. It was not possible to feel any affection for them. Even the men who handled them felt only a soft of vengeful hope in their capacities.
The Wabblers squatted in their racks for long hours. It was very cold, but they gave no sign. The sleek, swift-flying thing roared on and roared on. The Wabblers waited. Men moved somewhere in the flying thing, but they did not come where the Wabblers were until the very end. But somehow, when a man came and inspected each one of them very carefully and poked experimentally about the bottoms of the racks in which the Wabblers lay, they knew that the time had come.
The villain of the Wabbler story is of course man. It was man who set the “chronometer, tide-time gear, valves, compressed-air tanks, and all the balance of its intricate innards” on its appointed course; the intelligence that programmed — the word was not in general use yet in 1942 — this clockwork to “wabble” from side to side through the mud until it crawled beneath the keel of an enemy battleship to fulfill its destiny.
But after the Wabbler came the much more sophisticated idea of the von Neumann probe, which was no mere clockwork but a self-replicating spacecraft which would endlessly make copies of itself. “These replicas would then be sent out to other star systems. The original ‘parent’ probe could then pursue its primary purpose within the star system”. Unlike Leinster’s cute mines, the Von Neumann probes were almost spooky. Properly considered they were an agency whereby Man could possess or haunt matter, almost in the demonic sense, and by his creations drift through and suffuse the universe in a sentient cloud.
That disturbing thought — the idea of being surrounded by sentient alien dust — occurred to scientists who consoled themselves by reasoning that if von Neumann probes were possible then advanced alien civilizations would have deployed them already. The fact we don’t detect them suggests that aliens don’t exist.
The argument is symmetric. Any alien who notes the absence of von Neumann probes would similarly conclude that we do not exist (at least as advanced technological life forms) just as our failure to find swarms of such devices eating through the star systems can be taken as proof that aliens don’t exist in that sense either.
In 1981, Frank Tipler put forth an argument that extraterrestrial intelligences do not exist, based on the absence of von Neumann probes. Given even a moderate rate of replication and the history of the galaxy, such probes should already be common throughout space and thus, we should have already encountered them. Because we have not, this shows that extraterrestrial intelligences do not exist. This is thus a resolution to the Fermi paradox—that is, the question of why we have not already encountered extraterrestrial intelligence if it is common throughout the universe.
You can almost imagine some alien teacher lecturing to his pupil: “if this Man that you imagine exists, then where are his von Neumann probes? Since there are none then Man does not exist”.
But the Navy exists at all events. The USN, in its desire to maintain is dominance of the waves, actually plans to seed the oceans with Wabblers. “Back in 2005, the US Navy’s Office of Naval Research (ONR), along with the Defense Advanced Research Projects Agency (DARPA) began work on developing … a semi-autonomous controlled network of fixed bottom and mobile sensors, potentially mounted on intelligent unmanned underwater vehicles (UUVs) to keep a constant eye on littoral zones.”
The classic image of a destroyer captain listening, with white knuckle intensity, to the returns of his sonar pings is long obsolete. Today these things are managed remotely. “In early July 2012, the United States Navy (USN) responded to Iran’s threats to use warships and mines to close the strategic Strait of Hormuz – through which around 40 percent of the world’s energy travels – by deploying dozens of ROVs to the Persian Gulf.”
Diesel electric and conventional submarines function almost like mobile mines and the mobile sensor grid destroys their chief strength and amplifies their major weakness. In order to remain stealthy, conventional subs eschew high energy propulsion sources in favor of quiet AIP engines which produce only about as much power as a family sedan. While on AIP they cannot sustain any more than a very slow speed.
It was natural that the Navy would create a low energy counterpart to its own high-energy fleet units. The grid finds them while the physically powerful fleet units, with their unlimited energy resources and big weapon-filled hulls outrange them.
The next step of course was to cut the cord and get these remotely controlled vehicles to think for themselves.
Perhaps nothing epitomizes this class of autonomously powered, semi-sentient vehicles more than “gliders”. These cheap simple devices which can literally navigate round the world with precision powered only by wind and wave.
And in their peregrinations they will tirelessly literally scour the ocean for purposes — which may include finding AIP submarines — which their makers have destined them for. Perhaps the best known of these devices are made by Liquid Robotics.
Their purpose is simple. To become almost a wave, one with the wind, a creature of the foam — and from that vantage to watch anything and everything.
But there are swifter models; gliders which use temperature gradients to propel themselves, enabling them to literally circle the earth. They are designed to keep pace with an AIP submarine in the creep mode — and be cheap too. One hundred and fifty of the “expensive” prototypes were purchased for $53 million. In mass production they will probably cost a few hundred dollars each.
Liberdade class flying wings are autonomous underwater gliders developed by the US Navy Office of Naval Research which use a blended wing body hullform to achieve hydrodynamic efficiency. It is an experimental class whose models were originally intended to track quiet diesel electric submarines in littoral waters, move at 1–3 knots and remain on station for up to six months.
It will come as no surprise that some scientists are proposing to use similar gliders to explore the under-ice oceans of Titan. A native of Titan, finding these prowling the oceans of that planet might well say, “‘oh look mom, a von Neumann probe’. ‘Oh, no dear’, she might reply. ‘That’s just the USN making sure there are no Kilo class subs on Titan.’”
You can never be too sure.
Perhaps the correct metaphor for understanding why we don’t see von Neumann probes comes from ASW. From that vantage, the main purpose of such probes is to keep the aliens hidden in the first place, just as the role of the mobile sensor grid is to never allow the fleet to become visible. They are complementary. The role of the grid is to let the high energy fleet watch undetected from afar. The role of the high energy fleet in return, is to defend the mobile sensor grid and service it in the same way that machine guns cover a terrestrial minefield.
Perhaps that alien child can answer his teacher in a paraphrase of Arthur C. Clarke: “any sufficiently advanced civilization would be invisible to their inferiors.” Maybe, but clearly any sufficiently advanced navy would. Perhaps if mankind achieved a sufficient mastery of physics he would hasten to become unobservable himself. Is the ASW paradigm the answer to the Fermi Paradox? Maybe not. But the mobile sensor grid could be the USN answer to the conventional submarine.