Through billions of years of time, countless particles collide and arrange into different configurations. Sometime somewhere, by chance, a particular configuration is produced: a certain group of particles are arranged in such a way that they effectively form an efficient self-replicating nanobot.

In merely seconds, the nanobot start multiplying out of control, stripping necessary atoms from nearby matter and consume the whole planet shortly. Since they have no way of going into space, a period of quiet is ensued.

Sometime later, an meteor impact on this planet sends a number of these nanobots flying into space in all directions, and they go on a journey to conquer other planets and stars.

Life on earth originated in a similar way, even though DNA-based life seeks to replicate in a less direct/aggresive way. what prevents the above scenario from happening?

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    $\begingroup$ You're assuming these nanobots are going to need every atom from every nearby piece of matter; in which case, wouldn't they consume each other and keep their population in check rather than consuming the entire planet? $\endgroup$
    – Frostfyre
    Mar 25, 2015 at 19:37
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    $\begingroup$ @Frostfyre not every atom, but the atoms they are made up of. Also , if they consume each other they will just become a shifting glob of nanobots, and the edge of the glob will consume new matter to expand. $\endgroup$ Mar 25, 2015 at 19:39
  • $\begingroup$ If the point is the panspermia, why not have the nanobots created on purpose by some alien race, then they get loose, get blown to the stars, etc. They could even have been thrown to the stars on purpose as a way to conquer distant planets with slower than light methods. Then when the alien master race gets there all the valuable minerals are already mined and ready. $\endgroup$
    – AndyD273
    Mar 25, 2015 at 19:42
  • $\begingroup$ Until they reach a boundary they cannot or have no need to cross (water, perhaps?) and begin to adapt hunting strategies, whereupon they can theoretically reduce their own population to a single member of all the applicable atoms. $\endgroup$
    – Frostfyre
    Mar 25, 2015 at 19:43
  • $\begingroup$ Also, if it happened, where is it going to get the instructions to know how to build a new one just like itself? $\endgroup$
    – AndyD273
    Mar 25, 2015 at 19:53

2 Answers 2


What prevents the above scenario from happening?

Sheer improbability.

The likelihood of a nanobot like you're describing arising randomly is so incredibly tiny that it can be said to be impossible. This is akin to all the oxygen molecules in the room you're in all migrating to the corner of the room. It's physically possible, but of the nearly countless physical configurations possible for the molecules in that room, a vanishingly small portion of those configuration include the aforementioned scenario.

If nanobot components had some roots in naturally occurring chemical processes then the chance goes up significantly. However, they simply do not. Especially considering the details of the apparent use of free energy by the nanobots, there isn't a natural process I know of to support that type of use.

DNA based life did not start in such an improbable way. DNA did not randomly combine and begin operations. In fact DNA based life started with RNA, and very simple RNA at that.

  • $\begingroup$ So it could happen in some paralell universe? $\endgroup$ Mar 25, 2015 at 19:41
  • $\begingroup$ @whatissleep I'm not sure how adding a parallel universe makes this any more likely :) It could happen in this universe. A better approach might be a new type of organic life, life that spreads like fire, an anima-inflammo of sorts. $\endgroup$
    – Samuel
    Mar 25, 2015 at 19:51
  • $\begingroup$ @whatissleep If you look at every universe in an infinite multiverse, with trillions of years of time, then sure, why not. Any probability, no matter how small, multiplied by infinity, equals infinity. But if you're going to do that, why ask with a reality check tag? $\endgroup$
    – AndyD273
    Mar 25, 2015 at 19:51
  • $\begingroup$ Don't forget that the resulting nanobot would need to run on code....spontaneous c++? $\endgroup$
    – Jax
    Mar 25, 2015 at 20:13
  • $\begingroup$ @DustinJackson Oh, clearly they would be running assembly if anything. But self-replication could be purely logic, an ASIC could do it, no software required. $\endgroup$
    – Samuel
    Mar 25, 2015 at 20:17

The factor which will keep your spontaneous nanites from consuming their home-world and ultimately the entire universe is... change. Nanites are no more immune to change than any other aspect of existence.

The first generation of the little critters might have come out of the randomness with a perfectly crafted structure made of just the right elements that had come together into just the right geometry within a perfectly accommodating environment of temperature and gravity.

That blessed first nanite would have a virgin world full of resources to choose from, so it might succeed in spawning a few absolutely identical copies of itself. Those perfect duplicates would also have been born into an unravaged world, so they too might find all the parts necessary to sire flawless children. The perfect duplication might go on for a few generations, but sooner or later, the available parts (atoms) would start to run low. When 31 argon atoms are needed and only 23 are within reach, substitutions will have to be made.

Change will have crept into the system.

From there, the nanite Armageddon is inevitable. Before the little terrors have consumed more than a few cubic yards of planet, significant variations will start appearing in each successive generation. Those difference will lead to a fractioning of the nanite population into factions. This, and the growing scarcity of required elements will eventually lead to wars.

But their wars will be different than our counterparts in our human-scale world. These nanites have only two instincts, to eat and to spawn. The factions lack any common interests or goals with which they might forge peace with the other side. Their competition for survival is absolute with enemy corpses providing the precious rare elements need for each side to reproduce. They will fight until neither side is able to persist

...and if by some miracle one side prevails and is able to survive, the whole process begins again. Change wiggles in through the gaps in available elements. Distinctions grow and factions form, and then once again, to war they go.

Like humans, your nanites will spend most of their time and ability trying to kill each other. Luckily for the planet (and the universe), they will never get organized enough to get on with the destruction for which chaos created them.

  • $\begingroup$ If change is occurring then evolution is in play. This makes a draw very unlikely. As nanobot evolution progresses, a nanobot best fit for that environment, that world, would emerge and dominate. Introducing change introduces adaptability, which allows for world eating domination. But it's mostly irrelevant, if that first nanobot was created at all the most amazingly massive hurdle has already been overcome. Also, I know it's super nit-picky, but argon is a noble gas and probably wouldn't be used in nanobot construction ;) $\endgroup$
    – Samuel
    Mar 25, 2015 at 23:19

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