The subject of the vessel is saturated with claims. Every maker explains that its shape concentrates the aroma, that its thickness holds the heat, that its material is neutral. The difficulty is not that these sentences are false. It is that they mix three very different registers, and one no longer knows which one is being read.

The first register is that of what has been measured, with a sample size, a protocol and an effect size. It is narrow. Only one published experiment tests the shape of the vessel on specialty coffee, and only one half-contradicts it.

The second is that of physical reasoning that is coherent but unverified on the object. That a narrow opening retains odorant molecules is a solid idea, three and a half centuries old, and confirmed on the wine glass. That it works on a coffee cup served hot has never been measured.

The third is that of the sales pitch, which borrows its vocabulary from the second and its authority from the first, owing nothing to either.

This plate separates the three in every paragraph. When it writes that we do not know, that is not a gap in the research that prepared it: it is the result.