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Equation 27 · Part 2 · The Corner of the Equivalence Principle No Experiment Has Touched

subscript

η^sup\hat\eta_{sup}
subscript

What this part means

The lower label selects a particular version, component, or indexed member of the quantity. For example, x₀ and xₜ can be values at different positions.

Its job in the formula

A subscript distinguishes a version, component, step, or member of a quantity. It does not automatically mean multiplication.

The passage around this formula

Lay all of it out in one table, rows for experiments and columns for the five components, and four columns get real entries: ηcl\eta_{cl} constrained at the 10^{-15} level by MICROSCOPE, η^diag\hat\eta_{diag} constrained by every dual-species and clock test in the list, η^coh\hat\eta_{coh} constrained at the low- 10^{-9} level by Rosi and colleagues’ internal-superposition test, η^sup\hat\eta_{sup} constrained by Overstreet and colleagues’ gravitational Aharonov-Bohm result. The fifth column, η^ent\hat\eta_{ent} , has nothing in it — not a weak bound, not a preliminary number, nothing. The paper’s proposition on this point is not merely that the entangled component happens to be unmeasured; it proves, within its…

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Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

Open the illustrated subscripts: which member of a family? guide →

Sources cited in the article section

These citations provide research context; check each source for the exact claim it supports.