Talk, Nosh and Gridlock

I paid a flying visit yesterday to the beautiful city of Edinburgh in order to give a seminar at the Institute for Astronomy, which is situated with the historic Royal Observatory. I was there not long ago, in fact, to do a PhD examination but on this occasion all I had to was stand up in a lecture room and rabbit on for an hour or so. That part of it seemed to go reasonably well, in that no more than half the audience fell asleep while I wittered away.

The morning flight from Cardiff to Edinburgh was uneventful and got me there in time to chat with various people and have lunch before the talk. I elected not to rush straight from the seminar to the airport in order to return the same day, but stayed overnight giving some of  the locals the dubious pleasure of paying for my dinner and enduring my company during it, which they did with great patience. I’d like to thank Alan, John, Alina, Stefano and Brendan for rounding off such a nice day with such a pleasant evening.

In the restaurant we ended up setting each other little geometry problems drawn on napkins, to the palpable disdain of our waiter who clearly wanted us to leave.  However, since I had to get up at 5am the following morning (i.e. this morning) to get the flight back to Cardiff, we didn’t stay out too late. I got back to the B&B where I was billeted in good time to check last night’s football results  before retiring to grab some shut-eye. Newcastle United 4 Coventry City 1 was the result, so it was good news to end the day…

I had to get up at the ungodly hour of 5am in order to catch the flight at Edinburgh airport, but the return flight was right on time. This was fortunate because, not long after the plane landed, a blizzard descended on Cardiff. Snow has fallen intermittently all day. Although I’m a bit tired after getting up so early – hence the brevity of this post –  I’m relieved I managed to get back to work without any major travel hitches.

Anyway, my contribution to the little problem-setting session that took place between the plates and wine glasses was this one, which I was asked during the interview I had to undergo to get a place to study at Cambridge:

Consider an infinite square grid made as shown above from 1Ω resistors. What is the resistance between any two adjacent nodes of this network?

If you’re really interested, a general solution for the resistance between any two (not necessarily adjacent) nodes is given here but you should be able to get the answer for adjacent nodes by a much simpler line of reasoning!

Viva Voce

Just back from a flying visit to the beautiful city of Edinburgh, where I was involved in the examination of a PhD candidate at the Institute for Astronomy, which is housed on the site of the Royal Observatory.

For those of you not familiar with how this works, a PhD involves doing research into a particular topic and then writing up what you’ve done in a thesis. The thesis is a substantial piece of work, often in the region of 100,000 words (200 pages or so), which is then assessed by two examiners (one internal to the university at which the research was done, and one external). They read copies of the thesis and then the candidate has to defend it in an oral examination, which was what happened today, after which they make a recommendation to the university about whether the degree should be awarded.

At most universities the supervisor does not attend the oral examination, but is not normally required to go into hiding for the day, which is what seemed to happen in this case…

There aren’t many rules for how a viva voce examination should be conducted or how long it should last, but the can be as short as, say, 2 hours and can be as long as 5 hours or more. The examiners usually ask a mixture of questions, some about the details of the work presented and some about the general background. The unpredictable content of a viva voce examination makes it very difficult to prepare for, and it can be difficult and stressful for the candidate (as well as just tiring, as it can drag on for a long time). However, call me old-fashioned but I think if you’re going to get to call youself Doctor of Philosophy you should expect to have to work for it. Some might disagree.

As it happens, my own PhD examination 20 years ago was quite long (about 4hrs 30 minutes) and my external examiner was John Peacock, who happened to be the supervisor of today’s candidate Berian James. It wasn’t a deliberate consequence of me wanting to take vicarious revenge as external examiner on John’s student, but this turned out to be a long examination too. We did break twice (once, briefly, for the remembrance day silence and then for a longer period for lunch), but it was still a lengthy affair.

Obviously I can’t give details of what went on in the examination except that it was long primarily because the thesis was very interesting and gave us lots to discuss. In the end internal examiner Philip Best and I agreed to recommend the award of a PhD. Berian then went off to celebrate while we completed the necessary paperwork. At Edinburgh as in most UK universities, the examiners simply make a recommendation to a higher authority (e.g. Board of Graduate Studies) to formally award the degree, but in the overwhelming majority of cases they follow the recommendation.

After doing the paperwork I still had time to join the party for a glass or two of fizzy. At the do and at various points during the day I had the chance to say hello to some old friends, including Andy Taylor, Bob Mann, and Alan Heavens who all work at the ROE and Richard Nelson who was there for a meeting that I hadn’t known about when we arranged the date and time of the viva.

All in all, it was a very pleasant trip. Although I had to dash around to and from airports a bit getting to and from Scotland, all the planes went on time and since it’s less than an hour flying time from Cardiff to Edinburgh, it was all remarkably hassle-free.

Just before I left to get a taxi to the airport I had a quick chat with one of the PhD students, Alina Kiessling, who joked that I must be rushing off to write about the day on my blog. I never had time to read blogs when I was a PhD student (but  they hadn’t been invented then).

Perhaps I should start charging people to put their name in lights on In the Dark…