Insure/Ensure, Spectral Lines, and Ants

Today I Learned:
1) The word “insure” is, according to the OED, properly a variant of the word “ensure”, and was originally interchangeable with it. I found a published scholarly work from 1996 that uses “insure” in the modern sense of “ensure”… I’m not sure if that means it was acceptable practice as recently as twenty years ago or if it means that there were grammatical mistakes in the text.

2) It’s rather difficult to tell if a very young, hot star is getting nearer or farther away. Why? Well, the way you can typically tell whether a star is getting nearer or farther is by looking for red-shift or blue-shift in the spectral lines of the star. Spectral lines are specific wavelengths of light that are emitted or *not* emitted by hot matter, and they’re extremely specific — so if you see the spectral lines for, say, hydrogen, but they’re a little more blue than they should be, then that has to be from doppler shift.

The thing is, spectral lines are caused by absorption and emission of photons by the electrons in an atom. In a super-young, super-hot star, the outer layers of the star are so hot that their molecules are *stripped of electrons* — i.e., they’re plasma — so they have nothing to produce spectral lines. Ergo, no visible red- or blue-shift.

3) Ant trails are not so straightforward as I expected. Twice today, I tried tracing a line of ants back to the colony. I figured in one direction, it would fan out and dissipate, or converge on some sort of food, and in the other direction it would thicken and lead me to the next. Instead, in *both* directions, it thinned for a time, then would thicken in places and thin in other and branch in yet others… in neither case did I find a colony before I gave up (admittedly only a few minutes of searching).