If physicists analysed election results…

Posted in Bad Statistics, Politics, The Universe and Stuff on November 7, 2012 by telescoper

I think this is a wonderfully sharp satirical take on pollsters, physicists and statistics…

freakofnature's avatarFreak of Nature

Mainstream media outlets around the world have declared Barack Obama the victor in yesterday’s US presidential elections, but particle physicists at CERN say that the race is still too close to call.

With every state except Florida reporting, the New York Timesannounced that Obama had won the popular vote and easily gained the electoral college points needed to win re-election. The Princeton Election Consortium put the probability of Obama’s victory at 99.2%.

But that confidence level is still several standard deviations away from the point at which particle physicists would be willing to declare the next president. According to the norms of the field, pollsters would have to be 99.99995% confident that Obama had won before physicists would be willing to call the race.

“All we can say right now is there is some evidence that Barack Obama will return to the White House in January,” says Marcus Georgio…

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I Believe

Posted in Politics, Television with tags , , , , on November 7, 2012 by telescoper

I had decided to post this if last night’s  US Election result had turned out differently, but then thought I’d post it anyway.

Those of us of a certain age will remember the sense of incomprehension that spread around the world when Ronald Reagan was elected president of the United States in 1980 and were bracing themselves for similar trauma last night if Mitt Romney  had won. I’m sure I’m not the only person breathing a sigh of relief this morning. In deference to the losing candidate, I’ll echo the title of the song with a piece of Mitt Romney’s most inspirational rhetoric:

“I believe in an America where millions of Americans believe in an America that’s the America millions of Americans believe in. That’s the America I love.

Quite.

Anyway, lest you all get carried away with the euphoria of a second term for Barack Obama, I’ll say that although I’m glad  the electorate stepped back from the apocalyptic vision of a Romney victory, this is very much business as usual – with all that entails. Here is the late Gore Vidal’s summary of American politics (written in the 1970s).

 There is only one party in the United States, the Property Party … and it has two right wings: Republican and Democrat. Republicans are a bit stupider, more rigid, more doctrinaire in their laissez-faire capitalism than the Democrats, who are cuter, prettier, a bit more corrupt — until recently … and more willing than the Republicans to make small adjustments when the poor, the black, the anti-imperialists get out of hand. But, essentially, there is no difference between the two parties.

Taking Notes…

Posted in Education with tags , , , , on November 6, 2012 by telescoper

As if this week wasn’t busy enough, I’ve just received back the student questionnaires for my second-year module The Physics of Fields and Flows (which includes some theoretical physics techniques, such as vector calculus and Fourier methods, together with applications to fluid flow, electromagnetism and a few other things). I’ve only just taken up this module this year and was planning to prepare it over the summer, but circumstances rather intervened and I’ve had to put together more-or-less on the fly. I was, therefore, not inconsiderably apprehensive about the reaction I’d get from the students.

Fortunately most of the comments were fairly positive, although there were some very useful constructive criticisms, which I’ll definitely take into account for the rest of the term.

However, one recurring comment was that I write too fast on the whiteboard. In fact I go far more slowly than the lecturers I had at University. That brings me back to an old post I did some time ago about  lecture notes.

I won’t repeat the entire content of my earlier discussion, but one of the main points I made in that was about how inefficient many students are at taking notes during lectures, so much so that the effort of copying things onto paper must surely prevent them absorbing the intellectual content of the lecture.

I dealt with this problem when I was an undergraduate by learning to write very quickly without looking at the paper as I did so. That way I didn’t waste time moving my head to and fro between paper and screen or blackboard. Of course, the notes I produced using this method weren’t exactly aesthetically pleasing, but my handwriting is awful at the best of times so that didn’t make much difference to me. I always wrote my notes up more neatly after the lecture anyway. But the great advantage was that I could write down everything in real time without this interfering with my ability to listen to what the lecturer was saying.

An alternative to this approach is to learn shorthand, or invent your own form of abbreviated language. This approach is, however, unlikely to help you take down mathematical equations quickly.

My experience nowadays is that students simply aren’t used to taking notes like this – I suppose because they get given so many powerpoint presentations or other kinds of handout –  so they struggle to cope with the old-fashioned chalk-and-talk style of teaching that some lecturers still prefer. That’s probably because they get much less practice at school than my generation. Most of my school education was done via the blackboard..

Nowadays,  most lecturers use more “modern” methods than this. Many lecturers using powerpoint, and often they give copies of the slides to students. Others give out complete sets of printed notes before, during, or after lectures. That’s all very well, I think, but what are the students supposed to be doing during the lecture if you do that? Listen, of course, but if there is to be a long-term benefit they should take notes too.

Even if I hand out copies of slides or other notes, I always encourage my students to make their own independent set of notes, as complete as possible. I don’t mean copying down what they see on the screen and what they may have on paper already, but trying to write down what I say as I say it. I don’t think many take that advice, which means much of the spoken illustrations and explanations I give don’t find their way into any long term record of the lecture.

And if the lecturer just reads out the printed notes, adding nothing by way of illustration or explanation, then the audience is bound to get bored very quickly.

My argument, then, is that regardless of what technology the lecturer uses, whether he/she gives out printed notes or not, then if the students can’t take notes accurately and efficiently then lecturing is a complete waste of time. In fact for the module I’m doing now I don’t hand out lecture notes at all during the lectures, although I do post lecture summaries and answers to the exercises online after they’ve been done.

I like lecturing, because I like talking about physics and astronomy, but as I’ve got older I’ve become less convinced that lectures play a useful role in actually teaching anything. I think we should use lectures more sparingly, relying more on problem-based learning to instil proper understanding. When we do give lectures, they should focus much more on stimulating interest by being entertaining and thought-provoking. They should not be for the routine transmission of information, which is far too often the default.

I’m not saying we should scrap lectures altogether. At the very least they have the advantage of giving the students a shared experience, which is good for networking and building a group identity. Some students probably get a lot out of lectures anyway, perhaps more than I did when I was their age. But different people benefit from different styles of teaching, so we need to move away from lecturing as the default option.

I don’t think I ever learned very much about physics from lectures, but I’m nevertheless glad I learned out how to take notes the way I did because I find it useful in all kinds of situations. Effective note-taking is definitely a transferable skill, but it’s also a dying art.

Sometimes

Posted in Poetry with tags , on November 6, 2012 by telescoper

Sometimes things don’t go, after all,
from bad to worse. Some years, muscadel
faces down frost; green thrives; the crops don’t fail.
Sometimes a man aims high, and all goes well.

A people sometimes will step back from war,
elect an honest man, decide they care
enough, that they can’t leave some stranger poor.
Some men become what they were born for.

Sometimes our best intentions do not go
amiss; sometimes we do as we meant to.
The sun will sometimes melt a field of sorrow
that seemed hard frozen; may it happen for you.

by Sheenagh Pugh (b. 1950)

Fun with Vortex Rings

Posted in Education, The Universe and Stuff with tags , , on November 5, 2012 by telescoper

I decided to squeeze in a little bit about vortex rings into this morning’s lecture, partly because they illustrate the connections between fluid vorticity and magnetism, and partly because they’re fun…

Here’s an animation of a vortex ring showing how the fluid elements move around it (you might need to click on it to make it animate):

It’s quite easy to generate vortex rings in everyday situations, the simplest way being when a mass of fluid is impulsively pushed from an enclosed space through a narrow opening. In this case the poloidal flow is set in motion, at least in part, by interaction between the outer parts of the fluid mass and the edges of the opening. This results in fluid elements travelling in little circles, like those above, around a “core”; the direction of the vorticity is at right angles to these circles, i.e. in the toroidal direction. A vortex line can be formed from by joining together the vorticity vectors from each little circle to form a circle defining the core of the vortex ring. The behaviour of vortex lines in flows like this is entirely analogous to that of magnetic field lines. In this case, the vortex line follows the motion of the fluid, which is at right angles to it, so it propagates more-or-less without disruption. This is how most vortex ring toys work, such as shown in the two examples here; the second is far more dramatic!

The last video features some naturally-occurring vortex rings (as well as some  distinctly man-made examples). What I didn’t realise until I found this video last night is that whales and dolphins know how to make vortex rings too, only underwater. Why do they do this? Is there an evolutionary explanation? I doubt it! I think they’re just having fun.

A Name for Open Astrophysics?

Posted in Open Access with tags , , , , , on November 4, 2012 by telescoper

Regular readers of this blog may recall that  while ago  I posted an item in which I suggested setting up The Open Journal of Astrophysics. The motivation behind this was to demonstrate that it is possible to run an academic journal which is freely available to anyone who wants to read it, as well as at minimal cost to authors. Basically, I want to show that it is possible to “cut out the middle man” in the process of publishing scientific research and that by doing it ourselves we can actually do it better.

I was unwell for much of the summer, and more recently have had lots to do in connection with my forthcoming move to Sussex, so things have moved more slowly than I’d hoped but I just wanted to take this opportunity to give my assurance that this project is definitely going ahead. We have a (good) website design with ample space and other resources to run it, and a sufficient number of persons of suitable eminence have agreed to serve on the Editorial Board. It will basically be a front-end for the Arxiv, but will have a number of interesting additional features which make it a lot  more than that.  I’d prefer to save further details to the official launch, which is now planned to take place in January (as it would probably get buried in the pre-Xmas rush if we tried to launch before then). I can also confirm that the service we will provide will be free at the start, although if the volume of submissions grows we may have to charge a small fee for refereeing. And when I say “small” I mean small, not the hundreds or thousands of pounds charged by the rip-off merchants.

One thing I would like some ideas about, however, is the name. My working title for this project is The Open Journal of Astrophysics, which I think is OK but what I’d really like to do is break away from the old language of academic publishing as much as possible. I did think of the People’s Revolutionary Journal of Astrophysics, but feared that it might then split into Trotskyite and Marxist-Leninist factions. In any case the very name “journal” suggests something published periodically, whereas my idea is to have something that is updated continuously whenever papers are accepted. I’m therefore having second thoughts about having the word “Journal” in the title at all. Open Astrophysics might suffice, but I’m sure someone out there can come up with a better name. I know that Shakespeare said that a rose by any other name would smell as sweet, but I think a good title might make the difference between success and failure for this initiative…

That gives me the idea of enlisting the help of the denizens of the internet for some help in coming up with a better title; given the nature of the project, this seems an entirely appropriate way of proceeding. So please engage in collective or individual brainstorming sessions and let me have your suggestions through the comments box!

Se pieta di me non senti

Posted in Opera with tags , , , , on November 3, 2012 by telescoper

I heard this piece of music on Radio 3 earlier today and it completely blew me away.  I must get the DVD of the 2011 performance of Handel’s  Giulio Cesare from which it was taken, but in the meantime here’s a clip from Youtube to give you an idea. This is the marvellous Natalie Dessay as Cleopatra singing the da capo aria Se pieta di me non senti. It’s a truly sublime and moving performance from a singer at the very peak of her prowess. Brava!

Three Tips for Solving Physics Problems

Posted in Cute Problems, Education with tags , , , , , on November 2, 2012 by telescoper

I spent quite some time this morning going over some coursework problems with my second-year Physics class. It’s quite a big course – about 100 students take it – but I mark all the coursework myself so as to get a picture of what  the students are finding easy and what difficult. After returning the marked scripts I then go through general matters arising with them, as well as making the solutions available on our on-line system called Learning Central.

Anyway, this morning I decided to devote quite a bit of time to some tips about how to tackle physics problems, not only in terms of how to solve them but also how to present the answer in an appropriate way.

I began with the Feynman algorithm for solving physics problems:

  1. Write down the problem.
  2. Think very hard.
  3. Write down the answer.

That may seem either arrogant or facetious, or just a bit of a joke, but that’s really just the middle bit. Feynman’s advice on points 1 and 3 is absolutely spot on and worth repeating many times to an audience of physics students.

I’m a throwback to an older style of school education when the approach to solving unseen mathematical or scientific problems was emphasized much more than it is now. Nowadays much more detailed instructions are given in School examinations than in my day, often to the extent that students  are only required to fill in blanks in a solution that has already been mapped out.

I find that many, particularly first-year, students struggle when confronted with a problem with nothing but a blank sheet of paper to write the solution on. The biggest problem we face in physics education, in my view, is not the lack of mathematical skill or background scientific knowledge needed to perform calculations, but a lack of experience of how to set the problem up in the first place and a consequent uncertainty about, or even fear of, how to start. I call this “blank paper syndrome”.

In this context, Feynman’s advice is the key to the first step of solving a problem. When I give tips to students I usually make the first step a bit more general, however. It’s important to read the question too.

The middle step is more difficult and often relies on flair or the ability to engage in lateral thinking, which some people do more easily than others, but that does not mean it can’t be nurtured.  The key part is to look at what you wrote down in the first step, and then apply your little grey cells to teasing out – with the aid of your physics knowledge – things that can lead you to the answer, perhaps via some intermediate quantities not given directly in the question. This is the part where some students get stuck and what one often finds is an impenetrable jumble of mathematical symbols  swirling around randomly on the page.

Everyone gets stuck sometimes, but you can do yourself a big favour by at least putting some words in amongst the algebra to explain what it is you were attempting to do. That way, even if you get it wrong, you can be given some credit for having an idea of what direction you were thinking of travelling.

The last of Feynman’s steps  is also important. I lost count of the coursework attempts I marked this week in which the student got almost to the end, but didn’t finish with a clear statement of the answer to the question posed and just left a formula dangling.  Perhaps it’s because the students might have forgotten what they started out trying to do, but it seems very curious to me to get so far into a solution without making absolutely sure you score the points.  IHaving done all the hard work, you should learn to savour the finale in which you write “Therefore the answer is…” or “This proves the required result”. Scripts that don’t do this are like detective stories missing the last few pages in which the name of the murderer is finally revealed.

So, putting all these together, here are the three tips I gave to my undergraduate students this morning.

  1. Read the question! Some solutions were to problems other than that which was posed. Make sure you read the question carefully. A good habit to get into is first to translate everything given in the question into mathematical form and define any variables you need right at the outset. Also drawing a diagram helps a lot in visualizing the situation, especially helping to elucidate any relevant symmetries.
  2. Remember to explain your reasoning when doing a mathematical solution. Sometimes it is very difficult to understand what you’re trying to do from the maths alone, which makes it difficult to give partial credit if you are trying to the right thing but just make, e.g., a sign error.
  3.  Finish your solution appropriately by stating the answer clearly (and, where relevant, in correct units). Do not let your solution fizzle out – make sure the marker knows you have reached the end and that you have done what was requested.

There are other tips I might add – such as checking answers by doing the numerical parts at least twice on your calculator and thinking about whether the order-of-magnitude of the answer is physically reasonable – but these are minor compared to the overall strategy.

And another thing is not to be discouraged if you find physics problems difficult. Never give up without a fight. It’s only by trying difficult things that you can improve your ability by learning from your mistakes. It’s not the job of a physics lecturer to make physics seem easy but to encourage you to believe that you can do things that are difficult.

So anyway that’s my bit of “reflective practice” for the day. I’m sure there’ll be other folk reading this who have other tips for solving mathematical and scientific problems, in which case feel free to add them through the comments box.

At the Mountains of Madness

Posted in Literature, The Universe and Stuff with tags , , , , on November 1, 2012 by telescoper

Well, I don’t know whether it is some sort of Hallowe’en skit or what, but the estimable arXiv has certainly served up something unusual today, in the form of a paper by one Benjamin K. Tippett with the intriguing title Possible Bubbles of Spacetime Curvature in the South Pacific. Here is the abstract:

In 1928, the late Francis Wayland Thurston published a scandalous manuscript in purport of warning the world of a global conspiracy of occultists. Among the documents he gathered to support his thesis was the personal account of a sailor by the name of Gustaf Johansen, describing an encounter with an extraordinary island. Johansen`s descriptions of his adventures upon the island are fantastic, and are often considered the most enigmatic (and therefore the highlight) of Thurston`s collection of documents.

We contend that all of the credible phenomena which Johansen described may be explained as being the observable consequences of a localized bubble of spacetime curvature. Many of his most incomprehensible statements (involving the geometry of the architecture, and variability of the location of the horizon) can therefore be said to have a unified underlying cause.

We propose a simplified example of such a geometry, and show using numerical computation that Johansen`s descriptions were, for the most part, not simply the ravings of a lunatic. Rather, they are the nontechnical observations of an intelligent man who did not understand how to describe what he was seeing. Conversely, it seems to us improbable that Johansen should have unwittingly given such a precise description of the consequences of spacetime curvature, if the details of this story were merely the dregs of some half remembered fever dream.

We calculate the type of matter which would be required to generate such exotic spacetime curvature. Unfortunately, we determine that the required matter is quite unphysical, and possess a nature which is entirely alien to all of the experiences of human science. Indeed, any civilization with mastery over such matter would be able to construct warp drives, cloaking devices, and other exotic geometries required to conveniently travel through the cosmos.

Despite the unusual subject matter, it certainly doesn’t read like a skit, which means that if that’s what it is then it’s a very good one. Alternatively, it could just be that Dr Tippett might be taking it all a bit too literally. However, the paper is full of names that will ring a bell to anyone familiar with the works of H.P. Lovecraft, especially those relating to Cthulhu. Anyway, sounds like an ideal topic for further investigation. Time to put my grant-writing hat on!

P.S. The title of this post is taken from ref. [2] in the aforementioned arXiv paper.

Monster Mash-up

Posted in Biographical, Music with tags , , , on October 31, 2012 by telescoper

It’s Hallowe’en again, and although I feel I should concoct something appropriate, I really don’t have time. I’ve decided therefore to recycle a couple of items I’ve previously posted on this lamentable occasion.

We never had Halloween when I was a kid. I mean it existed. People mentioned it. There were programmes on the telly. But we never celebrated it. At least not in my house, when I was a kid. It just wasn’t thought of as a big occasion. Or, worse, it was “American” (meaning that it was tacky, synthetic and commercialised).  Cue this seasonable clip from Fry & Laurie

So there were no Halloween parties, no costumes, no horror masks, no pumpkins and definitely no trick-or-treat when I was a lad.

Having never done trick-or-treat myself as a child, I never really had any clue what it was about until relatively recently. I’d always assumed “Trick or Treat?” was a rhetorical question or merely a greeting like “How do you do?”.

In fact my first direct experience of this perculiar custom  didn’t happen until I was in my mid-thirties and had moved to a suburban house in Beeston, just outside Nottingham. I was sitting at home one October 31st, watching the TV and – probably, though I can’t remember for sure – drinking a glass of wine, when the front door bell rang. I didn’t really want to, but I got up and answered it.

When I opened the door, I saw in front of me two small girls in witches’ costumes. Behind them, near my front gate, was an adult guardian, presumably a parent, keeping a watchful eye on them.

“Trick or Treat?” the two girls shouted. Trying my best to get into the spirit but not knowing what I was actually supposed to do, I answered “Great! I’d like a treat please”.

They stared at me as if I was mad, turned round and retreated towards their minder who was clearly making a mental note to avoid this house in future. Off they went and I, embarrassed at being exposed as a social inadequate, retired to my house in shame.

Ever since then I’ve tried to ensure that I never again have to endure such Halloween horrors. Every October 31st, when nightfall comes, I switch off the TV, radio and lights and sit soundlessly in the dark so the trick-or-treaters think there’s nobody home.

That way I can be sure I won’t be made to feel uncomfortable.

Anyway, despite my own  reservations about Hallowe’en, I’ve decided to resurrect the following little video which seems to be appropriate for the occasion. It’s made of bits of old horror B-movies but the music – by Bobby “Boris” Pickett and the Crypt-kickers is actually the second single I ever bought, way back in 1973. I wonder if you can guess what the first one was?