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Monday, 11 June 2012

I Am Not Impressed With This Slime Mold

In the following video you can see a single-cell slime mold create a network between lumps of food. A large lump is used to represent Tokyo and then smaller lumps are then placed around it to represent the cities around Tokyo. The slime mold creates a network for passing the food around that according to the documentary's presenter is both 'absolutely identical' to the Tokyo rail system and more efficient*.  We also later see the slime mold 'do' the motorways in Britain, the best routes around Spain, some alternates to Route 66, and 'control' a robot..

* I would think that anyone praising Tokyo's efficiency is more to deal with the number of passengers it serves. What is the point of this comparison.


So why am I not impressed?




  1. The list of what the slime mold can do moves from the specific (replicate Tokyo's rail system and the UK's motorways - why not do both for each country?) to the general (best routes around Spain and alternates to Route 66 - what does alternate even mean in this context?). This seems to me like a pre-emptive example of the logical fallacy 'Moving the Goalpost', where the criteria of an argument are changed when shown to be untrue. You can see how the specific examples will break down if you ask why they do not do the UK's railways and Tokyo's motorways. Now you realise that they had two shots at each target (and possibly many more if varying the size of the lumps of food would affect how the slime mold grows).
  2. London is a primate city, meaning it is twice as large as the next biggest city in a country or contains at least a third of the population. Tokyo in the context of the Tokyo metropolitan area is in effect one too. They both exert far greater influence than any competing city. This creates the most likely circumstance in which a single-cell organism will succeed at a task like this as the cell must be placed somewhere to begin with. How would the mold fare if placed at Birmingham or Newcastle?
  3. Complexity is not intelligence. Check out this page on the 'Game of Life', a game invented by mathematician John Conway. Based on three simple rules surprising complexity emerges. Go to the 'Do All Patterns Stabilize Eventually?' section. The spacefiller ('Run Max') pattern impressed me the most but do give the puffer ('Run Puf Train') time to break out to the right - or run it at warp speed. Another example is the simple rules that govern bird flocking*. 
  4. If you made it as far as the slime-mould controlled robot (1:12:00) then I should make clear that it is the reporting that I am annoyed at - it doesn't even follow the unwritten rules of science journalism. It is not impressive that the slime mold is controlling a computer, you could take 'Big Fish, Little Fish' by Bob the Builder and adapt it to issue instructions to a robot. The way these robots work are that the slime mold is molded into an n-pointed shape. Each point is then attached to a sensor that adjusts the intensity of light being shined on that point. This affects the pulsing of the slime mold surrounding that point and that pulsing can then be used to guide the robot. The idea being that emergent complexity can be found (. 

* When I heard this I thought it would be a cool - and short - idea to simulate. As I was doing it though, it soon became clear that it would not be fun unless I could see the result. This meant I would have to learn how to use Java3D. I did spend several days programming with an excellent guide that I found online. Eventually other projects took over - but hey - koala on a red ball!

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