I’ve been reading about oxygen therapy, and at first was a bit surprised how inefficient it is. The actual human use of oxygen at rest (the amount that gets used as an oxidizer and ends up as CO2 or water) is about 0.25 liters per minute, yet oxygen concentrators meant to adequately supply a single person normally put out about 5 liters per minute. And although the oxygen concentration coming out of the machine is 90% or so, inefficiencies in the way it is actually delivered to the mouth and nose reduce that to where patients are usually breathing a concentration of less than 50% oxygen (as compared to the normal 20% oxygen concentration of the atmosphere).

People are making fun of President Trump for insistently thinking that a vaccine for the new coronavirus can be put out quickly, but as entertaining as it can be to make fun of politicians who are out of their depth in a highly technical area, the man has a point. A more constructive conversation might have gone like this:

I’ve been puzzled for a while as to why fentanyl has been killing so many people. Okay, gram for gram it’s much more potent than other opiates – something like a hundredfold. But drug dealers know this and dilute it accordingly. Junkies can be quite careless with their lives, but usually don’t try to kill themselves intentionally. So what explains the tens of thousands of deaths?

As a young student, I liked the idea of patents. Here, it seemed, was a system to properly reward the sort of person I was planning to become. But gradually I came to notice that everybody I admired for their scientific and engineering achievements took a rather dim view of patents. Being practical people, they sometimes took out patents (there was money in it), but without any feeling that the patent system was really the right way of rewarding them; on the contrary, they often pointed out absurdities in it. Richard Feynman, for instance, was the “inventor” listed on the patents of the nuclear airplane, the nuclear reactor, and the nuclear rocket, and treated the whole thing as a joke.

In an article which was mostly about another topic, I ran across this:

When they teach soldering, they say that you should heat the work, not the solder. This is true, but what’s also true is that to heat the work with a soldering iron, it helps a lot to have a bit of solder between the two: the heat conductivity of solder is much greater than that of air, and the small contact patch that a dry soldering iron makes with the work is miserable at transferring heat.

Economists have reasonable arguments against laws that prohibit hoarding and price gouging. But often they get carried away and take those arguments so far that they’re arguing that nobody could ever be a jerk for doing those things – that, say, a store owner who raises the price of flashlights after a hurricane is always doing the right thing.

One of the rules I was taught for writing, but never really respected, was not to reuse words: if you have to use it a second time, use a synonym. Eventually I realized what the real rule is. It’s okay to use the same word for the same thing. What is bad is to use the same word for a different thing. Even if the word would be a good fit for that second thing, if it’s already in use you should choose another, because otherwise readers will conflate the two.

There are some things about handgun sights which I’ve never seen explained properly – that is to say, so that even someone without any gun experience can look at the explanation and check that it is correct, rather than having to take something on faith. Yet they do have reasonably simple explanations.

Files and hacksaws were two tools that were around the house when I was a kid, and puzzled me quite a bit: I couldn’t figure out how anybody did much with them. Later I learned: the secret is in what was missing: the vise. The piece being filed or hacksawed should be clamped firmly in a heavy, solid vise which is bolted down tightly – or some other arrangement that is equally rigid. (If the workpiece is big and heavy enough, nothing is needed to hold it, but that’s uncommon.) Then you can apply the sort of force that is needed to remove metal fast, without the workpiece escaping or getting into a mutual dance of vibration with the cutting tool.