Foe (unit) Foe (unit) A foe is a unit of energy equal to 10 joules or 10 ergs, used to express the large amount of energy released by a supernova. The word is an acronym derived from a part of the pronunciation "ten to the power of fifty-one ergs". It was coined by Gerald E. Brown of Stony Brook University in his work with Hans Bethe, because "it came up often enough in our work". A bethe (B) is equivalent to a "foe". The "bethe" is named after Hans Bethe. It was coined by Steven Weinberg. This unit of measure is convenient
Conservation of energy the heat energy may be written where formula_21 is the temperature and formula_22 is a small change in the entropy of the system. Temperature and entropy are variables of state of a system. If an open system (in which mass may be exchanged with the environment) has several walls such that the mass transfer is through rigid walls separate from the heat and work transfers, then the first law may be written: where formula_24 is the added mass and formula_25 is the internal energy per unit mass of the added mass, measured in the surroundings before the process. The conservation