Dear Dirichlet, Issue 20

8 November 2024

Moonlighting agony uncle Professor Dirichlet answers your personal problems. Want the prof’s help? Send your problems to deardirichlet@chalkdustmagazine.com.

Dear Dirichlet,

I’m the groundskeeper at Edgbaston cricket ground, and England are playing a test match next month. The captain has not-so-subtly suggested to me that before England go out to bat, I should cut the grass extremely short under the rope around the outside. Is this friendly gardening advice, or does he have something up his sleeve?

— Where’s Wolf, Derby

Dirichlet says:
I’ve heard of your captain’s technique before. To reduce spin on the field, just remove the field at the boundary. A simple consequence of
\[\iint_{S}(\boldsymbol{\nabla} × \boldsymbol{F}) \cdot \mathrm{d} \boldsymbol{S} = \oint_{\partial S} \boldsymbol{F} \cdot \mathrm{d} \boldsymbol{r},\]
or as the pundits call it, Stokes’ theorem. Of course, I personally recommend zero as your boundary condition.

Dear Dirichlet,

I’m supposed to have been writing a dissertation about triangles, but I’ve spent most of the year slacking off instead. I had a great idea: my housemate’s also working on a triangle project, and he’s been writing, rewriting, and binning chapters at a record pace. I took a bunch of pages he wasn’t using, stuck them together, increased the font size, and submitted it—but I got a 100% plagiarism score on TurnItIn! Now what?!

— Mow money, mow problems, Selly Oak

Dirichlet says:
Ah, this is a classic ‘ship of thesis-us’ situation (also known as Trig-ger’s broom). Each time your housemate cut a chapter and replaced it with something better, you got pieces of his work, but the final dissertation was still his. Scaling it up won’t help—the triangles will still be flagged as similar! My advice: use ĉGPT.

Dear Dirichlet,

Wow. That opening Olympics ceremony! The incredible weather. The Assassins Creed horse thing. And the power of that Céline Dion performance. I can’t believe I’ve never heard of her before! Where should I start exploring her catalogue?

— Orla Coppie, London SE15

Dirichlet says:
When I’m covering Céline on karaoke, I start with ‘All summing fractal me now’, followed with ‘All bi(na)ry self’, and, bien sûr, ‘Pie chart will go on’. For the more discerning, I do a great rendition of ‘Where does Descartes eat now?’ (he’s banned from Burger King), and I always end the night with the undisputed Eurovision banger, ‘Poincaré pas sans moi’.

Dear Dirichlet,

I’m teaching a large class of undergraduates next term, and I’m worried my voice isn’t going to carry. I’ve got a number of small Bluetooth speakers and I think I read that they work better if set at better relative frequencies. I’ve done some simulations with $\sqrt{2}$ and $\sqrt{3}$, but the results were underwhelming. Where am I going wrong?

— Rose Water, Newcastle-under-Whelming

Dirichlet says:
The time for theory has passed. You have to get in the lecture theatre and do it for real. Bring all your speakers, and set their frequencies to a half, a quarter, an eighth,… You’ll find this is much more effective since fractions peak louder than surds.

Dear Dirichlet,

I’m really confused by my first year analysis course. Can you help?

— Sonia Sonic, The Wirral

Dirichlet says:
For every undergraduate, there is a lecture number $N$ such that for all $n > N$, the undergraduate is lost.

Heed Professor Dirichlet’s previous advice:

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