Geometry Joys, Murderous Maths, Simon teaching

Hyperbolic space

This is a model of hyperbolic space (7 triangles around a vertex). It’s an open problem of how far you can keep expanding your structure this way (possibly infinitely far, if you allow the surface to cross itself). Which is strange, because with 3, 4 or 5 triangles around a vertex you get a platonic solid, so you definitely can’t go on forever. If you put 6 triangles around a vertex, you end up tiling a plane, so you definitely can go on forever.

For 7 or more triangles, it’s this sort of saddle shape and we don’t know if we can go on forever. How far can you go even if you do it physically? Physically you’ll definitely end up not going on forever, but still interesting to see how far you can go.

Crafty, Experiments, motor skills, Physics, Together with sis

Some Physics Demos with Geomag

Rotating a merry-go-round with a “magic wand”
One beautiful thing about Simon’s recent return to Geomag is that, as it turned out, he is now capable of building all the tricky constructions on his own, without any help from the grown-ups
An example of a Gaussian Gun, a magnetic chain reaction to launch a steel ball at high speed. As soon as the rolling ball hits the magnet, another ball in the opposite side is launched.