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Occasionally you get a sense from kids that they can see something deeper in what you’re trying to teach them than you actually see yourself.

A couple of days ago we saw a very good planetarium program called “Black Holes: The other side of infinity” at the De Anza College Planetarium — a small but very good local planetarium that does numerous public programs.

One of the really nice things about this program was that in addition to the usual 2D rendition of gravity warping space(-time), they had a really nice animation of the warping of space(-time) in 3-dimensions, which was something like this:


(source: http://scienceblogs.com/startswithabang/files/2013/10/Curved_in_3D.jpg)

Okay, so now, apparently unrelated to the above:

This morning on the drive to school, Leo decided that he wanted to write in the air so that he could write a message and it would stay there. He had in mind  that when the car drove through it, it would come into the car and we would go right through the message, and it would come out the back … or something. I should have thought of sky writing, although I didn’t at the time. Nonetheless, we talked about the possibility of coloring the air molecules – but then the message would move with air currents. We talked about laser projection – but that would need to project onto fog, or something. (This is the obvious place that I should have thought of sky writing!) My last suggestion was thousands of nano-drones that we could program to for a pattern and stay in geocentric place, like the GPS satellites  – but then we would disturb them as we drove through. (We retrospectively figured out that this idea probably came from the micro-bots from Big Hero 6, but I had in more in mind Neal Stephenson’s “Toner Wars”.)

A few moments after the conversation died down Leo said (I’m only slightly paraphrasing): “I wish I had a black hole pen that could write on space time. I’ll bet that that would stay in place, except for gravitational warping.”