Archive for Physics

Spare me the Passive Voice!

Posted in Education with tags , , , , , on December 16, 2010 by telescoper

I’ve felt a mini-rant brewing for a few days now, as I’ve been reading through some of the interim reports my project students have written. I usually quite enjoy reading these, in fact. They’re not too long and I’m usually pretty impressed with how the students have set about the sometimes tricky things I’ve asked them to do. One pair, for example, is reanalysing the measurements made at the 1919 Eclipse expedition that I blogged about here, which is not only interesting from a historical point of view but which also poses an interesting challenge for budding data analysts.

So it’s not the fact that I have to read these things that annoys me, but the strange way students write them, i.e. almost entirely in the passive voice, e.g. “The experiment was calibrated using a phlogiston normalisation widget…”.

I accept that people disagree about whether the passive voice is good style or not. Some journals actively encourage the passive voice while others go the opposite way entirely . I’m not completely opposed to it, in fact, but I think it’s only useful either when the recipient of the action described in the sentence is more important than the agent, or when the agent is unknown or irrelevant. There’s nothing wrong with “My car has been stolen” (passive voice) since you would not be expected to know who stole it. On the other hand “My Hamster has been eaten by Freddy Starr” would not make a very good headline.

The point is that the construction of a statement in the passive voice in English is essentially periphrastic in that it almost inevitably involves some form of circumlocution – either using more words than necessary to express the meaning or being deliberately evasive by introducing ambiguity. Both of these failings should be avoided in scientific writing.

Apparently our laboratory instructors tell students to write their reports in the passive voice as a matter of course. I think this is just wrong. In a laboratory report the student should describe what he or she did. Saying what “was done” often leaves the statement open to the interpretation that somebody else did it. The whole point of a laboratory report is surely for the students to describe their own actions. “We calibrated the experiment..” is definitely to be preferred to the form I gave above.

Sometimes it is appropriate to use the passive voice because it is the correct grammatical construction in the circumstances. Sometimes also the text just seems to work better that way too. But having to read an entire document written in the passive voice drives me to distraction. It’s clumsy and dull.

In scientific papers, things are a little bit different but I still think using the active voice makes them easier to read and less likely to be ambiguous. In the introduction to a journal paper it’s quite acceptable to discuss the background to your work in the passive voice, e.g. “it is now generally accepted that…” but when describing what you and your co-authors have done it’s much better to use the active voice. “We observed ABC1234 using the Unfeasibly Large Telescope..” is, to my mind, much better than “Observations of ABC1234 were made using..”.

Reading back over this post I notice that I have jumped fairly freely between active and passive voice, thus demonstrating that I don’t have a dogmatic objection to its use. What I’m arguing is that it shouldn’t be the default, that’s all.

My guess is that a majority of experimental scientists won’t agree with this opinion, but a majority of astronomers and theoreticians will.

This guess will now be tested using a poll…


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Take a note from me…

Posted in Education with tags , , , , on December 14, 2010 by telescoper

Having just given a lecture on probability and statistics to our first-year postgraduate students I thought I’d indulge in a bit of reflective practice (as the jargon goes) and make a few quick comments on teaching to see if I can generate some reaction. Part of the reason for doing this is that while I was munching my coffee and drinking my toast this morning – I’m never very coordinated first thing – I noticed an interesting post by a student on a blog  that somehow wound up referring some traffic to one of my old posts about lecture notes.

I won’t repeat the entire content of my earlier discussion, but one of the main points I made 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 aren’t used to taking notes like this, 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 lecture 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.

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.

Next year we’ll rolling out a new set of courses here in the School of Physics & Astronomy at Cardiff University. The express intent of this is to pare down the amount of material lectured to create more space for other types of activity, especially more exercise classes for problem-based learning. The only way to really learn physics is by doing it.

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. Note-taking is a transferable skill, but it’s also a dying art.


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Ways of Thinking

Posted in Biographical, The Universe and Stuff with tags , , on November 25, 2010 by telescoper

I’m putting one more Richard Feynman clip up. This one struck me as particularly interesting, because it touches on a question I’ve often asked myself: what goes on in your head when do you mathematical calculations? I think I agree with Feynman’s suggestion that different people think in very different ways about the same kind of calculation or other activity.

There’s no doubt in my mind that I’ve become slower and slower at doing mathematics as I’ve got older, and probably less accurate too. I think that’s partly just age – and perhaps the cumulative effect of too much wine! – but it’s partly because I have so many other things to think about these days that it’s hard to spend long hours without interruption thinking about the same problem the way I could when I was a student or a postdoc.

In any case, although much of my research is mathematical, I’ve never really thought of myself as being in any sense a mathematical person. Many of my colleagues have much better technical skills in that regard than I’ve ever had. I was never particularly good at maths at school either. I was sufficiently competent at maths to do physics, of course, but I was much better at other things at that age. My best subject at O-level was Latin, for example, which possibly indicates that my brain prefers to work verbally (or perhaps symbolically) rather than, as no doubt many others’ do, geometrically or in some other abstract way.

Another strange thing is the role of vision in doing mathematics. I can’t do maths at all without writing things down on paper. I have to be able to see the equations to think about solving them. Amongst other things this makes it difficult when you’re working things out on a blackboard (or whiteboard); you have to write symbols so large that your field of view can’t take in a whole equation. I often have to step back up one of the aisles to get a good look at what I’m doing like that. Other physicists – notably Stephen Hawking – obviously manage without writing things down at all. I find it impossible to imagine having that ability.

But I endorse what Richard Feynman says at the beginning of the clip. It’s really all about being interested in the questions, which gives you the motivation to acquire the skills needed to find the answers. I think of it as being like music. If you’re drawn into the world of music, even if you’re talented you have to practice long for long hours before you can really play an instrument. Few can reach the level of Feynman (or a concert pianist) of course – I’m certainly not among either of those categories! – but I think physics is at least as much perspiration as inspiration.

In contrast to many of my colleagues I’m utterly hopeless at chess – and other games that require very sophisticated pattern-reading skills – but good at crosswords and word-puzzles. Maybe I’m in the wrong job?


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The Inconceivable Nature of Nature

Posted in The Universe and Stuff with tags , , on November 19, 2010 by telescoper

I had a couple of requests to post yet another Feynman clip. This one – about electromagnetic waves and swimming pools – is one that I vividly remember watching on BBC when it was first broadcast donkeys’ years ago. I think it’s totally wonderful.


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Through the Looking Glass

Posted in The Universe and Stuff with tags , , , on November 15, 2010 by telescoper

I’m afraid I’m too busy again for a proper post, so I’ll resort once again to the supply of wonderful Richard Feynman clips on Youtube. Here’s a particularly nice one, about the mysterious matter of mirrors. I might use this later on this year when I talk about parity to my particle physics class!


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Uncertainty

Posted in The Universe and Stuff with tags , on November 7, 2010 by telescoper

At the risk of turning this blog into a Feynman-fest – although I don’t think that would be such a bad thing, as a matter of fact – I couldn’t resist posting this little clip as a follow up to my previous one. In it he talks about a subject that has been a recurring motif on this blog – the importance of knowing when not to be certain.


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The Feynman Reaction

Posted in The Universe and Stuff with tags , , on November 5, 2010 by telescoper

I came across this clip of the great physicist Richard Feynman sort-of explaining magnetism, but was taken aback by some of the comments posted on Youtube in reaction to it. Some people appear to have found his response extremely arrogant, while others think he was just being honest (and trying his very best not to be patronising). I know what I think, but doubt if everyone agrees with my reaction.

I know the readership of this blog isn’t a fair sample, but I’d be very interested to see the general opinion on his comments. So please study the clip and complete the poll at the bottom.


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After Reading a Child’s Guide to Modern Physics

Posted in Poetry, The Universe and Stuff with tags , on October 26, 2010 by telescoper

This, written by W.H. Auden, is probably one of the most famous poems written about physics. A quick google about showed me that Cosmic Variance already featured it, along with a bit of an explanation of some of the scientific references contained within it. What I’m not sure whether what that article says about Auden’s own father was a physicist is correct. I always thought he was a medical doctor…

 

If all a top physicist knows
About the Truth be true,
Then, for all the so-and-so’s,
Futility and grime,
Our common world contains,
We have a better time
Than the Greater Nebulae do,
Or the atoms in our brains.

Marriage is rarely bliss
But, surely it would be worse
As particles to pelt
At thousands of miles per sec
About a universe
Wherein a lover’s kiss
Would either not be felt
Or break the loved one’s neck.

Though the face at which I stare
While shaving it be cruel
For, year after year, it repels
An ageing suitor, it has,
Thank God, sufficient mass
To be altogether there,
Not an indeterminate gruel
Which is partly somewhere else.

Our eyes prefer to suppose
That a habitable place
Has a geocentric view,
That architects enclose
A quiet Euclidean space:
Exploded myths – but who
Could feel at home astraddle
An ever expanding saddle?

This passion of our kind
For the process of finding out
Is a fact one can hardly doubt,
But I would rejoice in it more
If I knew more clearly what
We wanted the knowledge for,
Felt certain still that the mind
Is free to know or not.

It has chosen once, it seems,
And whether our concern
For magnitude’s extremes
Really become a creature
Who comes in a median size,
Or politicizing Nature
Be altogether wise,
Is something we shall learn

You can hear a recording, made in 1965, of the poet himself reading this poem here.


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The Day After: A Welsh Perspective

Posted in Education, Politics, Science Politics with tags , , , , , , , on October 21, 2010 by telescoper

It’s well after 11am and I’m still at home. Came down last night with some sort of bug that kept me awake nearly all night with frequent visits to the smallest room in the house. Whatever it is is still rumbling on so I’ve decided to stay at home until I give myself the all clear.

This sudden attack of lurgy is probably not connected with yesterday’s dramatic announcements of the results of the comprehensive spending review, which are now being dissected and analysed all over the mainstream press, the blogosphere, and countless common rooms around the country.

I haven’t got the energy right now to go over the ramifications in detail, but encourage you to read the whole thing, which is available in a nifty online reader for your perusal. I will, however, make a few brief comments, with particular emphasis on the situation here in Wales.

First, the announcement of large cuts to the teaching budget administered by HEFCE has clearly sent shockwaves through academia. It appears that only STEM subjects will continue to receive the state contribution and in future students will have to bear the full cost of tuition (but only after they’ve graduated and started to earn over the threshold of £21K). As a supporter of the Science is Vital campaign I was relieved that we seem to won a victory, although the war is far from over. However, I feel great sadness at the cost that our success seems likely to inflict on other disciplines. If you think these are nervous times for scientists, imagine what it must be like working in the Arts and Humanities.

Of course this all applies directly only to English universities: the budgets for Higher Education in Scotland, Wales and Northern Ireland are administered separately, so in principle things could work out very differently for Higher Education here in Wales.

However, the total amount of money available for the Welsh Assembly Government (WAG) to spend is fixed by the Westminster government through the Barnett Formula. This determines the overall cash for the devolved governments by allocating a proportion of what England spends on those things that are devolved., i.e. Wales is notionally allocated an amount for Higher Education which is proportional to HEFCE’s allocation and similar for other areas of spending such as Health. Once the size of the overall pot is fixed, however, the WAG is not obliged to spend its money in the same way that England does.

Buried in the pages of the CSR document is Wales’ allocation over the CSR period, which shows real terms cut of about 7.5% over the term. However, the Welsh Assembly Government’s reaction puts it rather differently:

In real terms, our total Budget is set to fall by around 3.1% per year on average, or 12% in total over the coming four years. This means that our Budget in 2014/15 will be £1.8bn lower in real terms than it is this year. Overall, in cash terms the reductions to our Budget will be 3% over the period.

Our capital Budget has been hit particularly hard, and will be cut by 40% in real terms – 34% in cash terms – over the next four years. This substantial reduction, particularly next year, where the cut is more than 25% in real terms, will clearly have a major impact on the private as well as the public sectors.

These figures seem different from those in the CSR document, which might be because of some nuance such as the way capital expenditure is accounted. If anyone can explain the discrepancy through the comments box I’d be grateful.

The main point is, though, that if Wales is going to keep current levels of investment in Higher Education (or even cut less than the English are doing) then it will have to take the money from elsewhere, which is not going to be easy to get through the Welsh Assembly. The picture, therefore, may not be any better here in Wales than it is in England, and could well turn out even worse, depending on how the WAG sets its own spending priorities. To complicate matters further, there’s an election next year for the Welsh Assembly, so there’s a wider political perspective to consider.

Within the overall issue of Higher Education spending is the question of whether Wales will decide to protect funding for STEM disciplines at the expense of all others. The WAG has already produced a document that suggests a strong focus on the so-called regional agenda, which may mean more money going into Further Education, vocational training, and part-time studies rather than, say, research-led science. I know what I would prefer, but whatever I say, it’s the WAG’s decisions that really count. And so it should be. After all, unlike me, they were elected!

Of course, if STEM subjects aren’t protected in Wales, those of us working in those areas are likely to lose even more ground to English universities, which already out-perform us in many respects. We have to make our case as best we can and see what happens.

However, I will end with some more local news which is extremely promising. Yesterday we had a staff meeting in the School of Physics & Astronomy at Cardiff University during which two extremely positive items came to light. One is that we will shortly be interviewing for the extra physics posts we advertised some time ago. Hopefully there will be a new Professor and three new Lecturers joining the staff in the very near future. I’m told we had a huge number of applicants for these positions, and the shortlists for these positions are very strong indeed. This is all very encouraging.

On top of this there is another exciting development on the horizon. After the disappointing outcome of the last RAE for physics in Wales, we have been thinking very hard at working closer with colleagues at Swansea with a view to building a sort of South Wales Physics Alliance. The departments are complementary in many ways: Swansea does particle physics, but Cardiff doesn’t; Cardiff does astronomy, but Swansea doesn’t. Where we are both relatively weak is in so-called “mainstream” physics, which is in the minority in both departments. With a bit of help, I think these two small(ish) departments could form a research institute that really challenges our competitors abroad (especially in England). I’m strongly in favour of this plan, and hope it goes ahead with full HEFCW support (including extra cash), but in this as in some many things, it’s a case of “fingers crossed”.


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Physics Nobel Prize 2010

Posted in The Universe and Stuff with tags , , , , on October 5, 2010 by telescoper

Just a quick newsflash: the 2010 Nobel Prize for Physics has gone to Andre Geim and Konstantin Novoselov (both of the University of Manchester)  “for groundbreaking experiments regarding the two-dimensional material graphene“.

For more details see the official announcement.

Heartiest congratulations to them both! Thoroughly well deserved.

ps. They were predicted to win two years ago by Thomson Reuters.

pps. It’s a clean sweep for UK-based scientists, so far. I wonder if the government is listening?