This week I agree to give an invited talk at the AGU, soldered some more of my satellite, advised a student, gave several short lectures, and edited some papers.  All of these are things professors get paid for-- except the editing.  Yet, ironically, the editing was my only paying work.

I am a reverse professor.  I do many of the career tasks an academic does, but I only get paid for the private sector component.  And that's the part that a 'true academic' would do for free.

In practice, this means I have traded any form of job stability for complete academic freedom.  I can research anything I wish, write about any topic from any stance, and speak freely.  I have 'virtual tenure', only with no paycheck.

Here we have two words, one in Arabic and one in Hebrew, which scholars of those languages will have no difficulty in recognizing as descending from the same ancient Semitic source. In Arabic the word means “error” in the sense of “error message” from a computer. The Arabic version is pronounced “khata” (with an emphatic “t”), and the Hebrew is quite similar.

I’m sticking with the Arabic for now, because this is the jumping-off point for an interesting bit of medieval mathematical history.