A foe is a unit of energy equal to 1044 joules or 1051 ergs, used to express the large amount of energy released by a supernova. An acronym f****or "[ten to the power o****f] fifty-one ergs", the term was introduced by Gerald E. Brown o****f Stony Bro****ok University in his work with Hans Bethe, because "it came up o****ften enough in our work". Without mentioning the foe, Steven Weinberg proposed in 2006 "a new unit called the bethe" (B) with the same value, to "replace" it. This unit of measure is convenient because a supernova typically releases about one foe of observable energy in a very short period (which can be measured in seconds). In comparison, if the Sun's current luminosity is the same as its average luminosity over its lifetime, it would release 3.827 W × 3.1536 s/yr × 1010 yr ≈ 1.2 foe. One solar mass has a rest mass energy of 1787 foe.