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Equation 2 · Part 5 · Fine-Tuning Without a Tuner: Selection Effects in Physics

multiplication

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

What this part means

Multiply the quantities on either side.

Its job in the formula

Multiply the quantities on either side.

The passage around this formula

Done correctly, the weak principle is pure statistics: it is a conditioning operation, identical in structure to correcting a biased sample in any other empirical science. A concrete instrument in this article’s own world makes the logic exact rather than analogical. A magneto-optical trap holds a cloud of atoms by continuously discarding the ones moving too fast to be captured by the cooling beams; every atom visible in the trap already survived a velocity cut. Someone who measured only the trapped cloud and concluded “the atoms in this room are unusually cold” would be committing exactly Eddington’s error — the room is not unusually cold, the trap is unusually selective, and the correction…

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Learn the underlying idea

Multiplication scales one quantity by another. A dot, a cross, or adjacent symbols can indicate a product.

Open the illustrated multiplication: combining factors guide →

Sources cited in the surrounding passage

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