# Re: Probability

```> Hi everyone, I am a complete layman but still got the illusion that
> maybe one day I would be able to understand the probability part of MW
> if explained in a simple way. I know it's the most controversal part
> of MW and that there are several competing understandings of
> probability in MW, but still: none of them make sense to me! If every
> line of history is realized then how can any line of history be more
> probable than any other?```
```
Mathematically, this isn't that hard to understand.  For example, consider
the equation (1 / (x^2)) between 1 and positive infinity on the x axis.  The
total area under the curve is 1, so it's a valid probability distribution.
The area between x = 1 and x = 2 is 1/2, or 50%.  So if you pick a "random"
point on the real number line between 1 and infinity, using that
distribution, half the time that point will land between 1 and 2.  For any
segment of the real line, you can determine exactly what the probability
will be that a point will fall on it--even though the distribution extends
forever.

The fact that there's an infinite number of choices doesn't mean that those
choices can't be normalized to a probability distribution.  Gaussians
(normal curves) describe most of the real data we measure in the sciences,
in one way or another--and the mathematical expression for a Gaussian
extends out forever.  Physics is filled with probabilities over infinite
domains.

Anna

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