Equation 63 · Part 1 · The Entry a Relabeling Cannot Write
Symbol ρ
What this part means
ρ is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Its job in the formula
ρ is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.
Full expression→Symbol ρ→Article meaning
The passage around this formula
an exact operator identity, not an approximation valid in some limit: the ledger for a system-only description of a system-plus-bath is precisely the bath’s own energy plus the coupling energy between the two, nothing more and nothing less. = [] for any joint state .
Learn the underlying idea
A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.
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Sources cited in the article section
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