What are “back-of-the-envelope” calculations?
The term “back-of-the-envelope” has several connotations: • calculations which are sufficiently straightforward or simplified so that they could, in principle, be written on the back of an envelope; • indicate which factors or physical processes are dominant; • indicate the bounds of behavior of the system; • usually intended to provide order-of-magnitude answers, or else something more precise but which still falls short of a full calculation done by computer simulation or numerical integration etc. For instance the calculations involving the properties of the Endor moon are back-of-the-envelope because they are realistic, but one or two of the quantities used are educated guesswork. This does not mean that the result is arbitrary. The density of the sanctuary moon must lie somewhere between the densities of Earth and Mars.
The term “back-of-the-envelope” has several connotations: • calculations which are sufficiently straightforward or simplified so that they could, in principle, be written on the back of an envelope; • indicate which factors or physical processes are dominant; • indicate the bounds of behavior of the system; • usually intended to provide order-of-magnitude answers, or else something more precise but which still falls short of a full calculation done by computer simulation or numerical integration etc. For instance the calculations involving the properties of the Endor moon are back-of-the-envelope because they are realistic, but one or two of the quantities used are educated guesswork. This does not mean that the result is arbitrary. The density of the sanctuary moon must lie somewhere between the densities of Earth and Mars. We use a plausible number which fits the general trend for planets of terrestrial composition, but without completing comprehensive and detailed geological structu
