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Equation 2 · Part 3 · Fine-Tuning Without a Tuner: Selection Effects in Physics

Symbol n_obs

P(λ∣observed)  ∝  P(λ)×nobs(λ)P(\lambda \mid \text{observed}) \;\propto\; P(\lambda) \times n_{\text{obs}}(\lambda)
nobsn_{\text{obs}}

What this part means

non_obs 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

non_obs is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

The passage around this formula

…whether they were selected into the sample. A universe with different constants that nobody observes has no such settled status — whether it exists at all, in what sense, and how to count it relative to ours (the term nobs(λ)n_{\text{obs}}(\lambda) in the expression above, the number or measure of observers a given value of λ\lambda produces) is precisely the disagreement the rest of this article has to work through. The trap analogy is exact about the logic of selection — you must condition on it — and silent about the…

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