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Equation 44 · Part 11 · A Horizon Is a Toll Booth, Not a Loophole

subscript

Eloc=E∞f(r),so thatEloc dτ=E∞ dt.E_{\rm loc} = \frac{E_\infty}{\sqrt{f(r)}}, \qquad\text{so that}\qquad E_{\rm loc}\,d\tau = E_\infty\,dt.
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

​ d t , with f(r) = 1-2GM/(rc2c^2) for Schwarzschild. A locally conserved (Killing) energy E∞E_\infty — the energy the same quantity would be assigned by a distant static observer — and the energy measured by the local static observer, ElocE_{\rm loc} , are related by the standard blueshift-on-the-way-down relation Eloc=E∞f(r),so thatEloc dτ=E∞ dtE_{\rm loc} = \frac{E_\infty}{\sqrt{f(r)}}, \qquad\text{so that}\qquad E_{\rm loc}\,d\tau = E_\infty\,dt. That second identity is the entire resolution in miniature, and it is worth deriving N⊥N_\perp[Γ\Gamma] both ways to see it operate. Hold the local energy budget fixed at ElocE_{\rm loc}=E0E_0' (a battery physically at the processor, delivering a fixed amount of locally measured energy) over a proper interval Δ\Deltaτ\tau :

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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.

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