iLife - Riding the glider

We have seen in previous pages that the blue-cell can craft a wide-variety of life-forms, but can it spawn independent life-forms in a controlled manner? One of the simplest life-forms not explored so far is the traditional glider, if the blue-cell could craft itself a glider then it would have a means of moving through its environment, will the possibility of taking occasional pit-stops to spawn colonies of other life-forms. Sounds too fanciful to be true perhaps, but in October 2001 Dr. William Paulsen of Arkansas State University sent me the following fascinating analysis which clearly illustrates the blue-cell can claim remarkable control over its environment.


The rest of this page is in Dr. Paulsen's own words and it should be noted that the blue-cell has now been given an unbounded board to play on, thus removing any non-standard, edge-based behaviour.

"The first discovery was that the intelligent cell can 'ride a glider'. Starting from the Y-start, one first moves SS< to get to the 'Loaf' position (since I haven't figured out how to return to the Y-start, I use this stable loaf position as my initial state). From the loaf, move: U<D>/DUL/DU/UL\R//SS/SS/SS/SS... [see demo 1]. It is interesting that when a glider is ridden, it accelerates to one third the speed of light.

The next step is to steer the glider. Although the glider can be turned 90 degrees by: /SS/SSD>SS>SS>... the glider will still move to the right, and repeating this process will put it back in the original direction [see demo 2]. However, it is easy to convert the glider to a loaf by /SS/R<\ or /SS/R</. This loaf can be in one of two orientations, both different than the original orientation, so using the above method to convert it back to a glider will turn it either 90 degrees or 180 degrees [see demo 3]. In this way, we can steer the glider anywhere in the plane.

The next phase is leaving a blinker in the trail. From a loaf, one can move: U<SL\D>RRUSUSSSSS/SU<DSSSSRSSSSSSLRR/\/USUDUDS> which reproduces a loaf, but also leaves a blinker far enough away as to not interfere with any of the above procedures [see demo 4]. In this way one can leave behind a trail of blinkers placed at key points in the plane.

Finally, from the loaf position one can move: U<DURURU/USL<RD>LUSD<>D<SULUL\R/ which not only fires a glider, but then boards a second glider to chase down the first [see demo 5]. In this way, one can fire as many gliders as desired, from any direction . It is well known that starting with a blinker, one can fire carefully aimed gliders at it to form more and more complicated Life structures. In this way spaceships, glider guns, and even breeders can be formed.

It might be interesting to see if any of the above procedures can be improved upon. Perhaps a computer search could find the minimum moves to do each step. This makes for an interesting open question".

Dr William Paulsen - October 2001

Update 2002: In Jan 2002 Dr Paulsen followed up this work with an extensive example of how the blue-cell can create a complete glider gun by combining and adapting these new concepts. So, for a grand finale, see building a glider gun

Update 2003: In Jan 2003 Dr Paulsen added to his findings with iLife optimal sequences

iLife pages: Maze of life V1 World domination Optimal sequences (new)
  The Y-start challenge Active oscillators Glider gun in 247 (new)
  Stable-state goals Riding the glider iLife play area
  Dense goals  Building a glider gun

material - Dr. William Paulsen 2001-2002
applet - © Andrea Gilbert 2000-2002