Fresh from their relatività speciale class, graffiti artists Avicenna and L. Bassi decide to test their acumen. They climb aboard opposite ends of a 21 m long train and synchronize their watches. The train starts up and quickly reaches a cruising speed of 180000000 m/s. (It is a very special train, indeed.) The plan? To investigate this funny concept called length contraction. At the predetermined moment on their watches, 1 minute after starting, they will open the windows and simultaneously spray their cans of paint, tagging the long brick wall beside the train. Since moving objects are contracted, the two spots will be closer together than 21 m.

Or will they be?