Sunday, April 5, 2009


It's tree time again!

We ate dinner outside for the first time this evening. Yay for living in the tropics!

Noah got a new toy today, which is fun because he can actually manipulate and play with it. Also fun because of its interesting crystal structure! 5 points for the first person to correctly identify the structure in the comments.

10 points to whomever volunteers to check any answers we receive, since I get lost with anything more complicated than FCC. Don't tell Ned.


  1. Must admit that I immediately enlarged the images to check out the structure, then realized that was dumb and went back to analyzing my OWN crystal structures (which are well-behaved fcc)!

  2. What exactly do you mean by "crystal structure"? It's not a lattice, so we can't identify it's space group. This is like some kind of trick question I would ask on a crystallography exam... Now, it's point symmetry is another question, but you'll have to ask Noah to take it out if his mouth before we can answer that one!

  3. There also appear to be points that can move there, which would complicate things, suppose. But what do I know? I only use cubic materials and dropped Uncle Bernie's class after 2 weeks.

  4. While the toy is not a lattice (excellent point), I think it is acceptable to draw the unit cell using all or part of the toy, and just assume it translates.

    It is an Icosahedron with four movable beads on the inside. There are parts that move. Take that, international tables of crystallography.

  5. I hate to break it to you, but I'm pretty sure that icosahedral isn't an acceptable unit cell shape and can't have translational symmetry.

    Rick is pretty sure our child will be born knowing all about thermodynamics after spending the last four months of its fetal development listening to me teach thermo. We can only hope so...

  6. I am pretty sure you can have icosahedral quasicrystals (you just don't have translational symmetry). I think that should count, based on the fact that we are dealing with a structure made out of painted wood and rubber string.

    Also I forgot to mention one of the cutest features of this toy, which is that Noah tries to put one bead in his mouth and ends up poking himself in the eye with another.