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Equation 49 · A Horizon Is a Toll Booth, Not a Loophole

What does this equation mean?

E∞=f E0′E_\infty = \sqrt{f}\,E_0'

Read the formula alongside the article passage below. Each part has a deeper page with its role in the equation, the supporting passage and nearby citations.

Inputs and operationssqrtfE_0'
Result or conditionE_infty
How to read the two sides of this formula. Follow the article passage for the meaning of each quantity.

This equation states an equality: the expressions on both sides have the same value under the article’s assumptions. Read the equation part by part below; each part has a contextual explanation and a link to its mathematical background.

Read it piece by piece

E∞E_\infty

Symbol E_infty

EiE_infty is part of the quantity the equation computes from the expression on the right.

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ff

Symbol f

f is an input to the expression that computes the quantity on the left.

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E0E_0

Symbol E_0

E0E_0 is an input to the expression that computes the quantity on the left.

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=

=

The expressions on both sides represent the same quantity under the stated assumptions.

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√

√

Take a square root.

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subscript

subscript

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.

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How to interpret it

Read it with the definitions, units, and assumptions supplied by the article.

What the article says around this equation

Now hold the asymptotic Killing energy fixed instead, at E∞E_\infty = f\sqrt{f}\,E0E_0' (the amount of energy it would cost a distant experimenter, at infinity, to deliver that same physical resource down to radius r ), and integrate over the corresponding coordinate interval Δ\Delta t = Δ\Deltaτ\tau/f\sqrt f :

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