How differently do mathematicians and historians think? It would seem the factor is about a billion.
I went to a lecture today by a history professor. His abstract had raised the question, “How many people alive today are descendants of Genghis Khan?” The answer he gave in the lecture was, around 16 million.
That was the word he used, simply “descendants”. However, after a question it emerged that he actually meant not just descendants but descendants in a direct male line, male to male to male to male (hence all with the same Y chromosome).
This is a sensational, spectacular, supernova kind of a difference. Suppose Genghis Khan lived 30 generations ago. In principle each of us has up to 2^30 ≈ 1 billion ancestors back then. (The actual number will be less because of overlaps and limited population size.) If one of your ancestors was Genghis Khan or William the Conqueror or Attila the Hun, that’s not very remarkable. But if your father’s father’s father’s … father was Genghis or William or Attila, that’s astonishing.
To this historian, the distinction was evidently a footnote.
[27 September 2016]
So far as I am aware, there is no historical evidence about Jesus Christ’s mother. I believe we just invented her. Thus one of Mary’s most unusual properties is indeed quite true: she was immaculately conceived.
[21 September 2016]
Here in Oxford’s spectacular mathematics building, we had our weekly meeting of the Chebfun team yesterday. Looking around the table, I realized that the people here working with me were from Italy, France, Germany, the USA, Pakistan, Iran, Japan, and China — and that I was the only one in the room with the right to remain permanently in the UK.
Seven-and-a-half of our nine salaries are paid by sources outside the UK.
More or less accidentally, the British people seem to have voted to bring all this to an end.
[7 July 2016]
The Bible has much to say about sheep, which are cared for by man as man is cared for by God. Walking the South Downs Way past hundreds of them yesterday, I was wondering about what sheep make of this relationship. It’s hard to put myself in the mind of a ewe, but perhaps an approximation goes like this. She probably knows pretty well that people run the show. She probably has a sense that the man who takes care of her and her lambs is on their side. A caregiver.
Being a sheep, she probably doesn’t reflect much on the question of “why”? Why does that man take care of us? What’s in it for him? Perhaps she dimly supposes that it’s because he likes us.
It doesn’t occur to her that his actual plan is to eat us.
[4 July 2016]
Jeremy Corbyn, leader of the Labour Party, was overwhelmingly defeated this week in a no-confidence vote: 40 votes for him, 172 against. That’s 81.1% against.
The press has been describing this fraction sometimes as “three-quarters”. I heard that expression on Radio 4 when the vote was first announced, and here it is again in yesterday’s Economist: “Jeremy Corbyn has been rejected by three-quarters of his MPs”. In fact, 81.1% is between four-fifths and five-sixths.
The BBC and the Economist are not sloppy. We can assume their choice of words was intentional. I guess in their editorial judgment, “three-quarters” sounds like English and “four-fifths” sounds like statistics.
[1 July 2016]
Dear NA friends,
I don’t normally sink so low as to send you an image from a movie, but this is irresistible. Kate and I just saw The Martian, in which Matt Damon is stuck on Mars and likely to die. But then the very cool young JPL astrophysicist genius Rich Purnell has the idea of slingshotting a spacecraft around Earth and back to Mars at great speed. Will it work? Cool young Purnell goes to the computer to run the math. He presses Enter, waits a tense moment, and then in one of the film’s big dramatic moments, gets this response on the screen,
| CALCULATIONS CORRECT |
Isn’t this delicious? It’s not every day that Hollywood shows the world the excitement of numerical computation.
[16 May 2016]
In this awful Trump election year, Republicans are announcing that they won’t vote for him; and of course, most of them add, they couldn’t possibly vote for Hillary either. The latest is Miami mayor Tomás Regalado. Today the New York Times reports that Regalado says he’s going to sit this one out.
The idea of sitting out an election gives another illustration of the strange disconnect between the mathematics and the psychology of voting. Mathematically, for a Republican to not vote for anybody has exactly the same effect as voting for Hillary, except with half the magnitude. Who would want their vote to be cut in half? But the human truth of voting has little to do with the mathematics. We all construct personal narratives of how we will or won’t vote, and out of millions of narratives, somehow or other, a president is elected.
[31 May 2016]