The glider is a pattern that travels across the board in Conway's Game of Life

Conway's Game of Life

The Game of Life, also known simply as Life, is a cellular automaton devised by the British mathematician John Horton Conway in 1970....

. It was first discovered by Richard K. Guy

Richard K. Guy

Richard Kenneth Guy is a British mathematician, Professor Emeritus in the Department of Mathematics at the University of Calgary....

 in 1970, while John Conway's group was attempting to track the evolution of the R-pentomino

Pentomino

A pentomino is a polyomino composed of five congruent squares, connected along their edges ....

. Gliders are the smallest spaceships, and they travel diagonally at a speed of c/4. The glider is often produced from randomly-generated starting configurations.

Importance

Gliders are important to the Game of Life because they are easily produced, can be collided with each other to form more complicated objects, and can be used to transmit information over long distances. For instance, eight gliders can be positioned so that they collide to form a Gosper glider gun. Glider collisions designed to result in certain patterns are also called glider syntheses.

Gliders can also be collided with other patterns with interesting results. For example, if two gliders are shot at a block in just the right way, the block will move closer to the source of the gliders. If three gliders are shot in just the right way, the block will move farther away. This "sliding block memory" can be used to simulate a counter

Counter

In digital logic and computing, a counter is a device which stores the number of times a particular event or process has occurred, often in relationship to a clock signal.- Electronic counters :...

, which would be modified by firing gliders at it. It is possible to construct logic gate

Logic gate

A logic gate is an idealized or physical device implementing a Boolean function, that is, it performs a logical operation on one or more logic inputs and produces a single logic output. Depending on the context, the term may refer to an ideal logic gate, one that has for instance zero rise time and...

s such as AND

Logical conjunction

In logic and mathematics, a two-place logical operator and, also known as logical conjunction, results in true if both of its operands are true, otherwise the value of false....

, OR

Logical disjunction

In logic and mathematics, a two-place logical connective or, is a logical disjunction, also known as inclusive disjunction or alternation, that results in true whenever one or more of its operands are true. E.g. in this context, "A or B" is true if A is true, or if B is true, or if both A and B are...

and NOT

Negation

In logic and mathematics, negation, also called logical complement, is an operation on propositions, truth values, or semantic values more generally. Intuitively, the negation of a proposition is true when that proposition is false, and vice versa. In classical logic negation is normally identified...

using gliders. One may also build a pattern that acts like a finite state machine

Finite state machine

A finite-state machine or finite-state automaton , or simply a state machine, is a mathematical model used to design computer programs and digital logic circuits. It is conceived as an abstract machine that can be in one of a finite number of states...

 connected to two counters. This has the same computational power as a universal Turing machine

Universal Turing machine

In computer science, a universal Turing machine is a Turing machine that can simulate an arbitrary Turing machine on arbitrary input. The universal machine essentially achieves this by reading both the description of the machine to be simulated as well as the input thereof from its own tape. Alan...

, so, using the glider, the Game of Life is theoretically as powerful as any computer with unlimited memory and no time constraints: it is Turing complete.

Hacker emblem

Eric S. Raymond

Eric S. Raymond

Eric Steven Raymond , often referred to as ESR, is an American computer programmer, author and open source software advocate. After the 1997 publication of The Cathedral and the Bazaar, Raymond was for a number of years frequently quoted as an unofficial spokesman for the open source movement...

 has proposed the glider as an emblem

Hacker Emblem

The Hacker Emblem was first proposed in October 2003 by Eric S. Raymond, who claimed a need for a unifying and recognizable symbol for his perception of hacker culture...

 to represent hackers because:

• The glider was "born at almost the same time as the Internet
  Internet
  The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...
  
   and Unix
  Unix
  Unix is a multitasking, multi-user computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs, including Ken Thompson, Dennis Ritchie, Brian Kernighan, Douglas McIlroy, and Joe Ossanna...
  
  ".
• The Game of Life appeals to hackers.

External links

• Glider at the LifeWiki
• The Glider: Proposal for a Hacker Emblem