Play with it

One page per chapter. Every number in the article is a control on one of these.

• 0 · Turn the stack yourselfThe greengrocer's stack of equal balls, in three dimensions. Drag it.
• 1 · Slide the rows togetherCircles of the same size, arranged in rows. The slider staggers the rows and pulls them closer.
• 2 · Add dimensions and watch the room goOne ball, and the box that just holds it. The slider changes the dimension.
• 3 · Try to settle it by handClick to drop circles. They refuse to overlap, and the packing you build is one of infinitely many.
• 4 · Break a certificate yourselfA working certificate in the plane. Each slider changes one of its parts.
• 5 · Count the same total twiceA small packing on the left, its frequencies on the right. Step through the count.
• 6 · The gap nobody has closedWhat can be built, against what has been proved impossible, in the dimensions where this repository has a certificate.
• 8 · Stretch until the two agreeA certificate and its Fourier transform. The slider stretches the certificate.
• 9 · Push the radius into the wallThe negative half of the balanced function has to fit inside a ball. The slider shrinks that ball.
• 11 · Watch the two halves closeOne direction rules every certificate out below a rate. The other builds one that reaches it. The slider raises the dimension.

Each page is self contained: no libraries and no network, so they work offline and from a file.