Since the most bloggable thing I’ve done in the past few weeks has been online shopping for Christmas presents while still in bed, here’s a story from a few weeks ago. It’s nerdy! But it involves cake!

I’d been having a slighty frustrating time at work, with a lot of back and forth that went like

Me: What are the results you’re getting for your simulations of [problem]?

Other person sends me a bunch of graphs.

Me: Ok, but are you sure that’s right? Those numbers just aren’t physically possible. (They were the equivalent of “I measured the size of my car and it was 16 km wide”)

Them: well I already I debugged my code.

Me: sure, but the numbers don’t make physical sense [blah blah physics talk]

Them: but there aren’t any bugs in my code, I’ve gone through it 3 times.

Me: I don’t care how many times you debugged, can’t you see the results you’re sending me are just not possible?

And so on. And, I have to admit, a fair number of side comments about “how do people get physics degrees if they can’t even tell when their calculations are giving them nonsense? Harrumph.”

So when I realized that a friend from church had a birthday coming up and I was going to see her the day before it, it seemed like a good idea to bake her a surprise cake. It would be a nice thing to do, and I find baking quite relaxing.

I had a friend staying with me at the time, so I didn’t want to fuss about with making something complicated. So I chose a simple recipe, one where you just melt the ingredients together. It called for a 19 cm square tin. I don’t have any square cake tins, but that was fine, because I did have a 22 cm round tin, which is almost exactly the same area, so the cake should bake the same way. I even calculated the percentage difference between the two, it’s about 5%.

So I greased and lined my big cake tin, and got to work melting butter and sugar together. I had a moment of doubt when it came to adding the flour. It just didn’t seem like a lot of flour for such a large cake tin. But I trusted the recipe and I knew that 22 cm round is very close to the 19 cm square it called for. So maybe it was just a recipe with a higher butter to flour ratio.

I had another doubt when I poured the batter into the tin and it didn’t really look like much. But the picture on the recipe was of quite a light cake, so it was probably going to rise a lot. It did have quite a bit of baking powder in it. And I’d gone to such trouble to make sure I was using a recipe that suited my big cake tin. So in the oven it went.

And 40 minutes later it came out, flat. Maybe 2 cm thick, at most.

Huh??

E., the friend who was staying, and I stared at this comically thin cake on the cooling rack. It must have deflated. So much for a simple recipe! Could we put on a tonne of icing to bulk it up? No, it was just too flat. Roll it up? No, it wasn’t flexible enough and anyway, it was round. Well I can’t use this as D.’s birthday cake. There’s nothing for it, I’ll have to make a second layer. At this point, it was getting late, so I set my alarm for 6 am and went to bed.

Fortunately, making a second layer was straightforward even in my 6am mental state, and I sandwiched them together well with some plum jam:

Why are the candles unlit in that photo? Because after all the trouble of making the cake, we discovered at the last possible minute before bringing it out to D. that we didn’t have any matches. Fortunately, this tipped the whole thing from “I thought baking would be a stress relief and instead I had to get up at 6 this morning!!!” to hilarious. So all’s well as ends well.

And as I was falling asleep that night, I realized the embarassing truth. Yes, a 22 cm round tin is equivalent to a 19 cm square tin. But my big cake tin isn’t 22 cm. It’s more like 28 cm. And it’s not as if I don’t know roughly what 22 cm looks like, I work with measurements all the time. So I should add another line to my exchange:

Me: Self, I don’t care how many times you’ve calculated that 22 cm round is equivalent to 19 cm square. Can’t you see that your cake tin just isn’t 22 cm?