h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Well, my interpretation of all that would be that since x is across the page and y is up the page, and z is out of the page, then in that table version x is across the table and y is up the table and z is out of the table, and then you go and confuse things by saying that the zeros have y=0.

That's why I asked you to explain it more clearly.

Well, do you think it's explained more clearly now?

(I used the model of x, y and z axes merely as a way of enabling non-mathematicians to grasp the concept.I really didn't anticipate the confusion that this seems to have caused. As I said, the OU programme didn;t use x, y and z nomenclature at all. They didn't need to as they has the 'visual' which they were able to rotate around as the commentary proceeded. I used the terms x and y coordinates as this is what most people would be familiar with.

No, I don't think it is any clearer now. My posting 101 is based on the way I think it is at the moment. All I want you to do is to insert a sentence saying that y is the height above the table. It can't be that hard, can it?

P.S. A question to the Answers to Correspondents' column in todays Daily Mail asks, 'Can anyone explain to me Riemann's Metric Tensor' which was taught to me in High School Mathematics but which I never understood'

Well, I studied maths to 'O' Level, and then my ONC in Physical Sciences took pure maths teaching nearly up to 'A' Level - but I've never come across Riemann's Metric Tensor.

I would say that this fuels the debate on whether standards are slipping in mathematics teaching

I studied Mathematics up to Leaving Certificate which is about probably slightly better than O level, and then I went on to do four years of Mathematics in college as part of an Engineering Degree, and also never encountered Riemann's Metric Tensor. I think I heard the word "tensor" once all those years.

I'd never even heard the word 'tensor'. (When term restarts I'll asked the 'A' Level Maths lecturer if its on her syllabus.

'All I want you to do is to insert a sentence saying that y is the height above the table. It can't be that hard, can it?'

Well, I thought these two sentences did exactly that:

The points at which the mountains' bases are at table level are known as the 'Riemann zeros'. These occur at the points where y=0.

However, I think what has happened is that I've used the convention from 'Solid Geometry' and applied it to a landscape model. I agree with what you said in a post above that, on an OS Map, W-E would be x and N-S would be y. Therefore elevation in this case has yo be given by z.

I think, having slept on it, I'll use a form of words whiuch I trhink you suggested further up.

See if that'a any better.

That seems better

You might wait to hear what Gnomon has to say about the critical line as being along 'y' instead of the 'x' - it's just that the imaginary number in the zeta function is what one normally thinks of as z = x + iy so to have the zeros along y would mean that you are using the convention z = y + ix. Apologies for being tedious about this, but conventions are often tedious.

tensors were bandied about in a course on elasticity - I recall

I forgot to mention - this was interesting all over again on a complete re-reading. It's a terrific entry and probably about ready to go - would you say?

I've changed it so that the Critical Line is now along x.

I'm feeling dreadful still today. I thought I might've been on the mend 'coz I spent much of yesterday out of bed. But things seem to have relapsed.

Just to say that I've added Gnomon and Pailaway to the Credits, due to their help (and patience) with ensuring that I got the axes of the Riemann 'zeros' mathematically correct.

Thanks, BigAl. Sorry for pestering you when you were unwell. Hope you are feeling better now.

The Entry certainly looks ready for picking to me.

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Well done BigAl!

Still unwell though. Main problem is extremely sore roof of mouth and gums which prevents me eating. Still alternate profuse sweating/shivering throughout the night and, today, had a headache this morning for the first time this illness.

However, I'm not as comatose as I was earlier in the illness, and I've managed not to return to bed so far today. Also prepared lunch for myself, Mrs BigAL and grandson.

Booked a visit to the tomorrow and he's gonna run some tests.

Well done, Al.

If necessary, get the doctor to send you into hospital for tests. They found out what was wrong with me in only four hours, and I was cured within a week (although I'm still recovering months later).

Congratulations Big Al!

Though I'm very sorry about your discomfort. Yes, by all means - doctors have been known to help.

I just dscovered that a Uni Project on the Great Mathematicias (starting with the Greeks) was started in 2000, but seems to have foundered.

Seems a worthy cause for someone to take on ...

Oops. It's at A482483