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What Do Gravitational Crystals Really Look (i.e. Move) Like?

In a recent blog, Stephen Wolfram discusses the idea of what he calls "gravitational crystals." These are infinite arrays of gravitational bodies in periodic motion. Two animations of mesmerizing movements of points were given as examples of what gravitational crystals could look like, but no explicit orbit calculations were given. In this blog, I will carefully calculate explicit numerical examples of gravitational crystal movements. The "really" in the title should be interpreted as a high-precision, numerical solution to an idealized model problem. It should not be interpreted as "real world." No retardation, special or general relativistic effects, stability against perturbation, tidal effects, or so on are taken into account in the following calculations. More precisely, we will consider the simplest case of a gravitational crystal: two gravitationally interacting, rigid, periodic 2D planar arrays embedded in 3D (meaning a 1/distance2 force law) of masses that can move translationally with respect to each other (no rotations between the two lattices). Each infinite array can be considered a crystal, so we are looking at what could be called the two-crystal problem (parallel to, and at the same time in distinction to, the classical gravitational two-body problem).
Education & Academic

An Exact Value for the Planck Constant: Why Reaching It Took 100 Years

Blog communicated on behalf of Jean-Charles de Borda.

Some thoughts for World Metrology Day 2016

Please allow me to introduce myself I'm a man of precision and science I've been around for a long, long time Stole many a man's pound and toise And I was around when Louis XVI Had his moment of doubt and pain Made damn sure that metric rules Through platinum standards made forever Pleased to meet you Hope you guess my name

Introduction and about me

In case you can't guess: I am Jean-Charles de Borda, sailor, mathematician, scientist, and member of the Académie des Sciences, born on May 4, 1733, in Dax, France. Two weeks ago would have been my 283rd birthday. This is me:
Education & Academic

New Derivatives of the Bessel Functions Have Been Discovered with the Help of the Wolfram Language!

Nearly two hundred years after Friedrich Bessel introduced his eponymous functions, expressions for their derivatives with respect to parameters, valid over the double complex plane, have been found.
In this blog we will show and briefly discuss some formerly unknown derivatives of special functions (primarily Bessel and related functions), and explore the history and current status of differentiation by parameters of hypergeometric and other functions. One of the main formulas found (more details below) is a closed form for the first derivative of one of the most popular special functions, the Bessel function J:
Education & Academic

Special Event: New Wolfram Language Resources for the Classroom

Earlier this year we launched Wolfram Programming Lab as the place to start learning the Wolfram Language. And since launch, we've received a lot of feedback and support from educators and students interested in using Programming Lab in their classrooms. Programming Lab was conceived and designed with teaching in mind, and to help make Programming Lab the best possible learning environment, we've developed some new tools for both students and teachers. We invite you to preview these new materials at a special virtual event, New Resources for the Classroom: Virtual Workshop for Educators.
Computation & Analysis

Computational Stippling: Can Machines Do as Well as Humans?

Stippling is a kind of drawing style using only points to mimic lines, edges, and grayscale. The entire drawing consists only of dots on a white background. The density of the points gives the impression of grayscale shading. Back in 1510, stippling was first invented as an engraving technique, and then became popular in many fields because it requires just one color of ink. Here is a photo of a fine example taken from an exhibition of lithography and copperplate art (the Centenary of European Engraving Exhibition held at the Hubei Museum of Art in March 2015; in case you're curious, here is the museum's official page in English).
Education & Academic

Celebrate Math Awareness with This Wolfram|Alpha Promo

April and Mathematics Awareness Month will soon be coming to an end, and so will these special offers on Mathematica and Wolfram|Alpha. As I mentioned in my last post, this year's Mathematics Awareness Month explores "the Future of Prediction" via mathematics and statistics. Ever since the earliest recognition of mathematics, people have used it to make accurate predictions not only in math but also in related fields.
Education & Academic

Analyzing Shakespeare’s Texts on the 400th Anniversary of His Death

Putting some color in Shakespeare's tragedies with the Wolfram Language

After four hundred years, Shakespeare's works are still highly present in our culture. He mastered the English language as never before, and he deeply understood the emotions of the human mind. Have you ever explored Shakespeare's texts from the perspective of a data scientist? Wolfram technologies can provide you with new insights into the semantics and statistical analysis of Shakespeare's plays and the social networks of their characters. William Shakespeare (April 26, 1564 (baptized)--April 23, 1616) is considered by many to be the greatest writer of the English language. He wrote 154 sonnets, 38 plays (divided into three main groups: comedy, history, and tragedy), and 4 long narrative poems.
Computation & Analysis

The 26.2 Blog

It’s four months into the new year. Spring is here. Well, so they say. And if the temperatures do not convince you, the influx of the number of runners on our roads definitely should. I have always loved running. Despite the fact that during each mile I complain about various combinations of the weather, the mileage, and my general state of mind, I met up with 37,000 other runners for the Chicago Marathon on October 11, 2015. As it turns out, this single event makes for a great example to explore what the Wolfram Language can do with larger datasets. The data we are using below is available on the Chicago Marathon results website. This marathon is one of the six Abbott World Marathon Majors: the Tokyo, Boston, Virgin Money London, BMW Berlin, Bank of America Chicago, and TCS New York City marathons. If you are looking for things to add to your bucket list, I believe these are great candidates. Given the international appeal, let's have a look at the runners' nationalities and their travel paths. Our GeoGraphics functionality easily enables us to do so. Clearly many people traveled very far to participate: