A radio host used an amazing metaphor to give a sense of how small a nanometer is:

If Texas were a meter wide, an ant would be a nanometer long.

I immediately concluded, Texas is a billion ants wide.

When you live in Texas, it certainly seems to have billions of ants, or even billions of types of ants, some of which are really scary, such as fire ants, that swarm up the unlucky leg that stumbled into their nest and cover its owner with venomous bites, an attack that occasionally proves fatal.

All the ants are different sizes too, begging the question, which species is the billion-wide ant? A quick calculation, using the Internet-generated value of 790 miles as the width of Texas, yields a value of 0.05 inch, which is 1/20 inch or 1.27 mm, for the ant length. That seems like one tiny ant, especially considering that this is the state with big hair, huge belt buckles, and Texas toast.

Sure enough, there’s no ant that small in Texas. I found a list of native Texas ants and patiently checked the size of each. The Pharoah ant seems to be the smallest, with a minimum size of 1/16 inch, or just under 2 mm, while the fire ant also has a minimum near 2 mm.

Random thought: So many scientists measuring so many ants…

Maybe the person wasn’t using Texas ants to measure Texas. It’s a mental exercise; no need to line up one billion ants to confirm the supposition. Maybe the person is familiar with smaller ants from a different state, country, or continent. I couldn’t find any smaller ants on the Internet, but there are surely plenty of undiscovered ones, some of which we may catalog before extinction. Alternatively, maybe the person was a little sloppy, deciding to use the width of Texas in inches, dividing by a billion since there are a billion nanometers in a meter, then thinking, What is a twentieth-inch long? and erroneously concluding, An ant.

To give this person a break, it’s hard to find a good example of something 1.27 mm long. The only thing I easily found was a single species of parasitic copepod with which few are familiar. A credit card is about 1 mm thick, not only is that about a fifth too small, it’s not nearly as fun to imagine credit cards marching across Texas.

Maybe Texas was, for once, too small for this thought process. If you use the continental US, for example, you get a billion items that are 0.1774 inches long, or 4.5 mm. That’s about as long as a small paper clip. The red imported fire ant also suits, but it ranges from 2.4 to 6 mm long, so you might picture the wrong one. Plus, it’s very scary to picture red imported fire ants spanning the continental US, at least for those of us who spent our childhoods in Texas.

I did not listen to the entire piece, so I don’t know why the presenter wished us to understand the size of a nanometer. If it was related to the size of SAR-CoV-2, I think the example was overstated. As viruses go, that one is a porker, to use another Texas term, at 120 nm diameter, and even the smallest known virus of any type is 17 nm. Maybe she was discussing something else though. Realizing that there is an enormous world of things we cannot see, scales at which human skin has the topography of the High Sierras and woven fabric is a gaping array of wide passages, is useful to resetting one’s perspective.

This is how my mind works. Nothing is at all obvious. I can always think of another question.

It can be exhausting.