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Ray Stoneham worries that a ¡°seismic shift to online discourse¡± will leave academics, who are not on first-name terms with modern-day referencing, ¡°in their ivory towers calculating the number of angels who could dance on a pin¡± (¡°Rewrite the source code¡±, Letters, March). That task is already well under way.

In 1995, Phil Schewe of the American Institute of Physics, using ideas from superstring physics, came up with the elegant estimate of the number of angels on the point of a pin as 10 to the 25th power. This has since been challenged by Anders Sandberg, of the Royal Institute of Technology, Sweden, who addresses the crucial problem of when the angels actually break into a dance.

So, lively disputation will continue in the ivory tower.

R. E. Rawles
Honorary research fellow in psychology
University College London