Re: No comments on "An Exceptionally Simple Theory of Everything"

In article <filst7$fd5$1@xxxxxxxxxxxxxxx>,
Roman Werpachowski <roman.werpachowski@xxxxxxxxx> wrote:

Are you 100% sure that the perturbation series would converge if you
summed up all terms?

I was in a quantum field theory class in graduate school, and a
student asked precisely this question: "Professor, has it been proved
that these perturbation series converge?" The professor cheerfully
replied, "Oh, no, in fact they've been proved to diverge," and
proceeded with his lecture. The student audibly sobbed and laid his
head on his desk.

As I understand it, what the professor said is quite true: the
perturbation series that arise in this sort of calculation are
asymptotic series, not convergent series. The partial sums approach
the right answer for a while, but after some number of terms they blow
up.

I certainly don't know the details of how all this works, but as I
understand it the number of terms at which things start to go bad is
pretty large in QED calculations, and the accuracy you can get to
before you run into trouble is much better than the 12 decimal places
we're talking about here.

-Ted

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