New and Improved

Last update: 23 March 2017

Update Log (covers finer-grained changes)

The Analytical Engine

In 1837, Charles Babbage invented The Analytical Engine, a mechanical card-programmed digital computer which anticipated almost every aspect of the electronic computers which would not appear for more than a century afterward. These pages are a virtual museum where you can explore the Engine both through historical documents and an emulator which allows you to experience for yourself what it would have been like to program a steam-powered computer. New: 2017 update adds a JavaScript/HTML5 Web-based emulator and several new sample programs.

Pitch Drop

The longest continuously-running scientific experiment demonstrates that even extremely viscous fluids will eventually flow as the liquids they are. Do it yourself instructions are included.

Orbits in Strongly Curved Spacetime

An interactive animation illustrates how orbits around compact objects such as neutron stars and black holes depart drastically from Kepler's laws, and explains why.

Update: January 2017 update uses HTML5/JavaScript animation, eliminating the need for Java, and improves graphics rendering. The original Java version remains available.

The RetroPsychoKinesis Project

Retropsychokinesis is the claimed ability of certain subjects to alter random data generated, but not examined, prior to the time the data are presented to the subject. Crazy, you say! Well, there's certainly no mechanism in mainstream physics which could permit such an effect, yet experiments conducted by a number of different researchers over the last 20 years suggest, compellingly according to some analyses, that the probability of the results obtained in such experiments being purely the result of chance is sufficiently low that they would be considered evidence of a causal mechanism in most scientific disciplines. The archives of the Project provide a broad collection of research reports (reproduced with the permission of their authors and publishers) and literature citations related to this elusive but, if real, profoundly important phenomenon.

Retropsychokinesis Experiments On-line

You can explore the phenomenon of Retropsychokinesis (if indeed it exists) through these on-line experiments. Each presents you with a sequence of random data produced by the HotBits radioactive random number generator which is presented by a visual feedback program. The random sequence is pre-recorded but not examined prior to your performing the experiment. Results are logged in a secure and transparent fashion, and a daily summary of results to date is published on the Web. Complete source code is available for all of the experiment programs.

Update: Twentieth anniversary update adds HTML5/JavaScript visual feedback programs, eliminating the need for Java.

The Probability Pipe Organ

The Probability Pipe Organ lets you run interactive experiments which demonstrate how the results from random data approach the normal distribution expectation as the number of experiments grows large. Update: HTML5 animation eliminates the need for Java applet support. (The Java version remains available.)

The Autodesk File

The history of Autodesk and AutoCAD told through contemporary documents, edited and annotated by Autodesk founder John Walker. You can read this 900 page book on-line on the World-Wide Web, or download a copy to read or print off-line in either PostScript or Adobe Acrobat PDF format. New: Fifth edition (2017) updates to modern Web standards, typography, and navigation.

Project Pluto

In the late 1950s and early '60s Project Pluto aimed at developing a nuclear powered cruise missile which could fly three times the speed of sound at low altitude with unlimited range and deliver nuclear devastation to multiple targets with pinpoint accuracy. It was one of the most bizarre concepts of the age of unlimited nuclear optimism, and got as far as ground testing a full scale flight weight propulsion system.

GAU-8 Avenger

If there is a pyramid of badassery when it comes to guns, the GAU-8 Avenger, carried by the A-10 Thunderbolt II (“Warthog”) close air support aircraft, is near the pinnacle. Explore the details of this bad boy.

Rocket Science

Rocket engineering is complicated and demanding, but rocket science is pretty straightforward. Explore the rocket equation, which governs the operation of all rockets, and understand why it's so difficult to get to orbit from the surface of the Earth and why multistage rockets make sense.

The Army's Flying Saucer

In the late 1950s, the U.S. Army investigated a flying saucer as an airborne replacement for the ubiquitous Jeep. This is the story of the Avro Canada VZ-9 Avrocar, one of the most curious projects of the “anything goes” era of aviation.

Slide Rule

Before computers and calculators, there were slide rules. It is difficult for people today to appreciate just how magic it was to be able to carry a small tool, made of bamboo and plastic, that could perform many of the computations of engineering and science which used to be so tedious in mere seconds, as long as you were happy with its limited precision. This document explores this vintage computing tool, using it to solve a variety of problems ranging from loading a turnip truck to interstellar flight.

Frisky Molecules

Essays about a variety of highly reactive and/or explosive molecules. Don't try this at home.

Clash of Ideologies: Communism, Islam, and the West

Western politicians say, “We're not at war with Islam.” But Islam is more than a just a religion. Its scriptures specify a political system, civil and criminal law, economics and trade, laws of war, and other matters which other major religions leave to civil authority, and some of these policy prescriptions conflict with Western values. This essay explores whether the West should treat these aspects of Islam as an ideology, like communism, fundamentally incompatible with its values, and how best to confront it.

Islam and Political Freedom

Is Islam compatible with political freedom? This document combines data from the Pew Research Center and Freedom House to investigate how empirical evidence addresses this question.

Kerbal Space Program Screenshot Gallery

Kerbal Space Program is a computer game in which the player builds spacecraft, aircraft, and spaceplanes and sends them on various missions. Not only is the game a great deal of fun, playing it helps develop an intuitive sense for rocket design and engineering and orbital mechanics, even among people who already understand these topics at the mathematical level. The graphics in the game are superb. This document is a collection of screen captures from missions I've flown.

Uranium Enrichment

To understand the news about negotiations with aspiring nuclear powers, it's important to grasp the technical fundamentals of both paths to nuclear weapons. This document describes the science and engineering behind enriching natural uranium for use in civil nuclear power reactors or weapons. A companion document discusses plutonium production.

Plutonium Production

To understand the news about negotiations with aspiring nuclear powers, it's important to comprehend the technical fundamentals of both paths to nuclear weapons. Here are the physics, chemistry, and engineering behind the production of plutonium for nuclear weapons applications, described for non-specialists. A companion document discusses uranium enrichment.


In an op-ed (never published) from July 1988 I ask whether the government of the United States is losing its legitimacy: whether citizens continue to believe it has the “consent of the governed”.

ANTarctica—Fourmilab South Pole Expedition 2013

We decided to celebrate our fortieth wedding anniversary by going South for the winter in January 2013. This being Fourmilab, no half measures would suffice short of going all the way—to the South Pole. We'd already been to the North Pole so, hey, we could become officially bipolar! This photo essay chronicles the expedition.

Floating Point Benchmarks

There are many disadvantages to being a balding geezer. In compensation, if you've managed to survive the second half of the twentieth century and been involved in computing, there's bearing personal witness to what happens when a technological transition goes into full-tilt exponential blow-off mode. I'm talking about Moore's Law—computing power available at constant cost doubling every 18 months or so. When Moore's Law is directly wired to your career and bank account, it's nice to have a little thermometer you can use to see how it's going as the years roll by. This page links to two benchmarks I've used to evaluate computer performance ever since 1980. They focus on things which matter dearly to me—floating point computation speed, evaluation of trigonometric functions, and matrix algebra. If you're interested in text searching or database retrieval speed, you should run screaming from these benchmarks. Hey, they work for me.

New September 2012 update adds Haskell to the C, FORTRAN, QBasic, Ada, Common Lisp, Java, JavaScript, Pascal, Perl, Python, Ruby, Smalltalk, and Visual Basic (6 and .NET) implementations of the original floating point benchmark, and includes a comparison of the relative performance of these languages.

Paleo Postings

This is a collection of postings from Fourmilog and documents on this site which relate to the paleo/primal/ancestral diet and lifestyle.