Equation 1 · Part 3 · What a Biosignature Has to Rule Out
=
=
What this part means
The expressions on both sides represent the same quantity under the stated assumptions.
Its job in the formula
The equals sign connects the complete expression on the left with the complete expression on the right. Both sides must have compatible units.
Full expression→=→Article meaning
The passage around this formula
If no gas can be trusted individually, the natural move is to look for a property of the whole atmosphere. The most general candidate is thermodynamic disequilibrium: life is a persistent chemical engine, so a biosphere should hold its planet’s atmosphere away from the composition it would relax to if all permitted reactions ran to completion. The quantity is the available Gibbs energy — the difference between the free energy of the observed composition and that of its equilibrium state at the same elemental abundances, temperature and pressure: . Krissansen-Totton, Olson and Catling computed this across Earth history and reported values that make the appeal obvious and…
Learn the underlying idea
An equals sign says that the expression on its left and the expression on its right have the same value under the stated definitions and assumptions.
Open the illustrated equality: what the equals sign claims guide →
Sources cited in the surrounding passage
These citations provide research context; check each source for the exact claim it supports.