What primordial radioactive nuclides (isotopes) still exist in the Earth's crust? To figure that out, we might need to know the original abundances of various nuclides in the matter that now makes up the Earth's crust. I haven't found good data on that. But it's pretty easy to calculate what the abundances would have to … Continue reading Is there any niobium-92 left?
Plain text extensions is an obsolete feature of the GIF (version 89a) image format. Essentially, it allows an animated GIF to have ASCII text frames, as well as the usual graphical frames. As far as I know, it was pretty much never used at all. The only GIF file with plain text extensions that I'm … Continue reading GIF plain text extensions
Where are the northernmost and southernmost naturally-growing trees in the world? I thought it would be easy to find the answer, but it turn out, not so much. Northernmost The northernmost trees are most certainly Dahurian larch (Larix gmelinii) trees growing in north central Russia. They are apparently somewhere in the marked region below, or … Continue reading The northernmost and southernmost trees
X-Face is an odd little graphics format, designed around 1990 as a standard way to include your picture/icon/avatar in the email messages you send. It's not exactly a file format; it's a special string of text that can be included in email headers. A number of email applications supported it, and maybe some still do. … Continue reading X-Face format
In how many different ways can an isolated neutral non-exotic atom decay? When an atom decays, it spontaneously changes into something else. That "something else" is inevitably two or more particles, none of which is the same kind of atom as the original. I also need to also explain what a "kind of atom" is. … Continue reading Simple classification of radioactive decay
Suppose we start at Cape Horn, at the southern tip of South America. We are challenged to travel from there to Tasmania (the big island south of Australia). We can travel freely over land, but only for X consecutive kilometers over water. How small can X be, and still allow us to reach Tasmania? Ground … Continue reading How to walk around the Earth
MacPaint is a paint program for early Macintosh computers. You can see it, and try it out, at the Internet Archive: <https://archive.org/details/mac_Paint_2>. Its native image file format is very limited, and very obsolete. But a large number of MacPaint files were created, back in the day, and some of them can still be found. For … Continue reading Survey of MacPaint brush patterns