I suspect they meant micrometers. I tried looking at the original article in “Nature”, but it’s a paywall site.
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I was thinking the same, micrometers, but maybe nanometers, thought that’s quite thin!
I also wonder how often Autocorrect is involved. If you’re writing on any Apple device, it’s always lying in wait, just waiting to strike. I fight with it constantly, and frequently see it actually change correctly-typed words to entirely different words after the fact, based upon what it (mistakenly) believes is the context of the sentence. It’s really poorly designed.