This was all meant to be in analogy to the physical world, where such a constructor could be used to build almost anything, perhaps operating at the atomic-scale.
It turns out that we can get much simpler self-replicators if we (a) ignore the "universal constructor" ability, and only focus on self-replication; and (b) choose cellular automaton rules which make self-replication easier, rather than using cells to encode "programs". This approach gives things like Langton's Loops https://en.wikipedia.org/wiki/Langton%27s_loops
The self-replicating property described in the article seems like an extreme form of this approach: the rules are so tailored for replication that they can't do anything else.
Of course, making such simplifications sort of defeats von Neumann's original purpose, since such highly-tailored rules are less "realistic", and hence don't particularly help us build physical self-replicators; and even if we could, they wouldn't be particularly useful without the "universal constructor" ability.
Yes. In von Neumann's last book "Theory of Self-Reproducing Automata", he thought about machines having viable offspring. This was more than a trick with patterns. He had invented the architecture of working computers, and was now moving on.
As a math grad student at Harvard around 1980, the wine flowed freely on Friday afternoons. I nevertheless headed over to the biology department, where cannabis-fueled discussions centered on work like von Neumann's.
Maybe the universe just doesn't use the right rule though.
We ourselves and everything around us would be that evidence...it's finding out if everything is made up of cellular automata that's the hard part.
Or, more generally, some superimposed versions of me partially overlapping, as can be seen with those overlapping Es in the original article.
>Or, more generally, some superimposed versions of me partially overlapping, as can be seen with those overlapping Es in the original article.
Maybe - it depends on the complexity of not just you but everything around you. There may be billions of similar yous around you, with some variation based on their history, but it's not close enough 'you' for your arbitrary definition.
I guess what I'm saying is, it really depends on how it all works. The interactions of different cellular automata can still give rise to incredible complexity that might make identical yous very difficult or impossible. Twins have similar circumstances to a high degree but even they can be different physically and are always different experimentally.
Also look into fractals, since they are self similar.
Aren't cellular automata deterministic, but the universe is non-deterministic at the quantum level?
Most games and simulations contain RNG's to make things interesting, quantum uncertainty seems to look very similar to my naive self.