From Steven Hall, Leigh, Greater Manchester, UK
Joshua Sokol reports the idea that the granularity of space-time acts as a form of friction, shedding energy into the stitching of space (27 May, p 28). I suggest it has another effect: to make space-time “stiff”.
It limits how curved space-time can become: a radius of curvature less than the grain size is not possible. In other words, at very small scales, the gravitational field cannot be stronger than a maximum value. This would mean that if you put more and more mass into a small volume, there comes a point when this mass is not “visible” through its effect on gravity.
