Bob Cook <[email protected]> wrote: > I have always thought that the binding energy released in a normal > “chemical reaction” was equivalent to a small change in mass. Is this not > the case? > Yes. Every form of energy production always converts mass to energy, always in the ratio from special relativity. That includes mechanical energy releases from a falling object or an unwinding spring; chemical energy (molecules changing; changes in electron bonds); and nuclear energy (changes to the nucleus).
Every form of energy storage always increases mass to the exact same extent. When you wind up a spring or move a rock 1 m up, you store energy and increase mass. I doubt any technology could measure such small changes in mass, but they are there. Other relativistic effects can be measured even on this scale, especially time, which is the fundamental quantity we measure with the most precision (1 part in 10^16 last I checked). Nowadays, when you move an atomic clock 10 m up to another floor, and compare it to one left behind, you can measure the extent to which time speeds up in the earth's reduced gravitational field. - Jed
