Whenever my graduate thesis adviser once told me “as soon as you start drawing lines in the air no one knows what they hell you are talking about.”

This was typically in response to someone in the lab elaborating a point by drawing an imaginary graph in the air with their fingers.

If you ever tried to do this while talking to him he would usually chuck a dry-erase marker or a chunk of chalk at you, and make you go up to the board and draw your graph properly.

This is also something I try to encourage in the shop. Whenever someone starts drawing in the air or using their finger as parts I always hand them a sharpie and something to write on.

Those simple graphs, figures, or diagrams often become beautiful, palimpsestic drawings conveying both the idea itself, and the beauty of the underlying thought process behind it.

If you are as interested in chalk-board drawings as I am, check out Bye bye blackboard, a website showing some of the chalk board drawings on display in the Special Exhibitions Gallery at the Museum of the History of Science, Oxford.

Here is one I really liked:

Sir Martin Rees

Astronomer Royal

‘Some of us suspect that there is more to physical reality than what we’ve traditionally called ‘our universe’ — the aftermath of ‘our big bang’. Moreover, other big bangs could give rise to cosmoses that behave very differently — with more structure or less; with galaxies that are bigger, smaller, or nonexistent. These diagrams consider what the aftermath of the big bang would have been like if two particular parameters were different from the values in our actual big bang: the quantity Q that measures how smooth the universe is, and Einstein’s cosmological constant ‘Lambda’. The shading delineates regions where galaxies could form.’