Vibrating Pin Screen

This table full of shaking pins forms patterns as the vibration frequency is varied. These patterns flow across the surface of the table like liquid.

Explanation

Thousands of pins hang loosely through holes on this table. The table vibrates using a strong motor, causing the pins to shake. The table is programmed to shake in a particular set of patterns.

The heads of the pins act as tiny mirrors that reflect light into your eyes. The reflections resemble the surface of a rippling pool of water.

Extras for Experts

What do pulsating colours on squids and pinscreens have in common?

They both work using cellular automaton theory.

In this theory, a larger object is composed of many small cells or domains. Each cell or domain can exist in one of a few states. The states of these domains influence the states of their neighbours. The neighbouring domains then go on to influence their neighbours, producing a complex pattern that is governed by simple rules.

In Vibrating pinscreen, each pin exists in one of three states; receptive (before excitation), excited (moving) and refractory (after excitation).

When a pin is in the excited state, it pushes the receptive pins nearby into an excited state as well. After being excited, it enters a refractory state where it will not become excited for a while.

These simple rules add up to make a very complex work.

Some squid use a cellular automaton mechanism to produce complex moving patterns on their surfaces without conscious control.

Questions to Ask

What would happen if you vibrated a pinscreen at a regular frequency? How would the pins affect each other?

Further Reading

• Ward Fleming’s Vibrating pinscreen site
  http://www.pinscreens.net/agallery4.htm
• Cellular automaton at Wolfram’s Mathword
  http://mathworld.wolfram.com/CellularAutomaton.html
• Beyer, WA, 1985. Stanislaw M. Ulam’s Contributions to Theoretical Theory. Letters in Mathematical Physics 10, p232-233

Vibrating Pin Screen
The pins shaking in the table create patterns that appear to move and flow.

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