In a recent paper, Dr Jacobson argues that observations made of synchrotron radiation produced by the Crab nebula (the remnants of a supernova observed in 1054) limit the granularity of space.

ECONOMIST: Planck-scale physics

Some people believe that the proportionality assumption about radiation should be made because it gives a "conservative" estimate of possible risks.

WSJ: The Panic Over Fukushima

With more emotion than sense, electronic components, machine parts and even towels made far from Fukushima have required radiation checks or been turned back by Italy and China, among others.

ECONOMIST: A spreading cloud of economic and human costs