Conway's Game of Life

In 1970, mathematician John Horton Conway invented a game called Life. Conway was intrigued by John von Neumann's theories about self-replicating automata: simple mathematical formulae representing virtual "life forms" that could be depicted in a virtual world. Of course, in von Neumann's day the "virtual world" was a piece of graph paper with some squares filled in (squares being the life forms), but still, it was a pretty cool idea. Conway took von Neumann's ideas a step further, creating a computer simulation of the graph paper-based automata, and forcing the automata to follow simple rules:

The universe of the Game of Life is an infinite two-dimensional orthogonal grid of square cells, each of which is in one of two possible states, live or dead. Every cell interacts with its eight neighbours, which are the cells that are directly horizontally, vertically, or diagonally adjacent. At each step in time, the following transitions occur:

1. Any live cell with fewer than two live neighbours dies, as if by needs caused by underpopulation.
2. Any live cell with more than three live neighbours dies, as if by overcrowding.
3. Any live cell with two or three live neighbours lives, unchanged, to the next generation.
4. Any tile with exactly three live neighbours cells will be populated with a living cell.

The initial pattern constitutes the 'seed' of the system. The first generation is created by applying the above rules simultaneously to every cell in the seed — births and deaths happen simultaneously, and the discrete moment at which this happens is sometimes called a tick. (In other words, each generation is a pure function of the one before.) The rules continue to be applied repeatedly to create further generations.

Conway's Game of Life often starts with a very simple playing field: mostly blank, with a few little bits filled in. What's fascinating is how complexity arises from the simple rules above, as they operate on the seed (the initial condition of the game). Some crazy things happen, including "guns" (pictured above), in which base cells seem to shoot virtual pellets. (When Bill Gosper at MIT discovered/invented guns, he won a $50 prize from Conway.)

Since 1970, Conway's Game of Life has been implemented on virtually every computer platform, either as a time waster or a nice way to get started with simple graphics programming. You can even get Life on the iPhone. To get a feel for Life, try playing The irRegular Game of Life, a nice Flash game in which you solve puzzles by creating automata (you do have to sit through an ad first, though). For a more traditional version of Life, check out this Java version (warning: kinda slow). To learn more about Conway's famous game, read up at Wikipedia.

The Prehistoric Bacteria That Helped Create Our Cells Billions of Years Ago

We owe the existence of our cells—the very building blocks of life—to a chance relationship between bacteria that occurred more than 2 billion years ago. Flash back to Bio 101, and you might remember that humans, plants, and animals have complex eukaryotic cells, with nucleus-bound DNA, instead of single-celled prokaryotic cells. These contain specialized organelles such as the mitochondria—the cell’s powerhouse—and the chloroplast, which converts sunlight into sugar in plants.

Mitochondria and chloroplasts both look and behave a lot like bacteria, and they also share similar genes. This isn’t a coincidence: Scientists believe these specialized cell subunits are descendants of free-living prehistoric bacteria that somehow merged together to form one. Over time, they became part of our basic biological units—and you can learn how by watching PBS Eons’s latest video below.

Stones, Bones, and Wrecks
Buckingham Palace Was Built With Jurassic Fossils, Scientists Find

The UK's Buckingham Palace is a vestige from another era, and not just because it was built in the early 18th century. According to a new study, the limestone used to construct it is filled with the fossilized remains of microbes from the Jurassic period of 200 million years ago, as The Telegraph reports.

The palace is made of oolitic limestone, which consists of individual balls of carbonate sediment called ooids. The material is strong but lightweight, and is found worldwide. Jurassic oolite has been used to construct numerous famous buildings, from those in the British city of Bath to the Empire State Building and the Pentagon.

A new study from Australian National University published in Scientific Reports found that the spherical ooids in Buckingham Palace's walls are made up of layers and layers of mineralized microbes. Inspired by a mathematical model from the 1970s for predicting the growth of brain tumors, the researchers created a model that explains how ooids are created and predicts the factors that limit their ultimate size.

A hand holding a chunk of oolite limestone
Australian National University

They found that the mineralization of the microbes forms the central core of the ooid, and the layers of sediment that gather around that core feed those microbes until the nutrients can no longer reach the core from the outermost layer.

This contrasts with previous research on how ooids form, which hypothesized that they are the result of sediment gathered from rolling on the ocean floor. It also reshapes how we think about the buildings made out of oolitic limestone from this period. Next time you look up at the Empire State Building or Buckingham Palace, thank the ancient microbes.

[h/t The Telegraph]


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