## More Order-of-Magnitude Physics

Posted in Cute Problems with tags , , , on April 25, 2019 by telescoper

A very busy day today so I thought I’d just do a quick post to give you a chance to test your brains with some more order-of-magnitude physics problems. I like using these in classes because they get people thinking about the physics behind problems without getting too bogged down in or turned off by complicated mathematics. If there’s any information missing that you need to solve the problem, make an order-of-magnitude estimate!

Give  order of magnitude answers to the following questions:

1. What is the maximum distance at which it could be possible for a car’s headlights to be resolved by the human eye?
2. How much would a pendulum clock gain or lose (say which) in a week if moved from a warm room into a cold basement?
3. What area would be needed for a terrestrial solar power station capable of producing 1GW of power?
4. What mass of cold water could be brought to the boil using the energy dissipated when a motor car is brought to rest from 100 km/h?
5. How many visible photons are emitted by a 100W light bulb during its lifetime?

## Failing A-levels

Posted in Education with tags , , on April 17, 2019 by telescoper

As it is tangentially related to yesterday’s post I thought I’d comment on an article in The Times with the headline

# University grades: firsts for quarter of students with lowest A levels

The piece (which you probably won’t read as it is behind a paywall) goes on to imply that the success at degree level of students who got poor A-levels results is the result of ‘grade inflation’.

My take on this is somewhat different. To me it just confirms what I’ve thought for years, namely that A-levels are virtually useless, either as a preparation for undergraduate study or as an indicator of academic potential. If they are are a guide to anything at all, it is to the quality of the school the student was lucky enough to attend.

It’s not only a shame that UK universities rely on A-levels so heavily for student recruitment but also a disgrace that institutions are punished in league tables whenever they take on students with low results. And if they do a good job educating such students to high levels of achievement they get attacked in churlish articles accusing them of lowering standards.

The assumption behind this is that there should be a near-perfect correlation between entry and exit qualifications. That is not the case at all, and why on earth should it be?

Look at this the other way round. Oxbridge only accepts students with the highest A-levels results, so why do these Universities not award more first-class degrees? Dare I suggest that perhaps not all the students they select have the aptitude their school qualifications suggest?

I noticed this the other day. It’s a list of skills needed for the job market in 2020.

Strangely, ‘rote learning’, ‘uncritical regurgitation of factoids’, and ‘ability to perform formulaic tasks’ are not on the list. They’re not much use as a preparation for university study either. So why does the UK school education system place such an emphasis on precisely these useless activities, to the exclusion of actually useful things?

## In Praise of Omnibus Science

Posted in Education, Maynooth with tags , , , on April 16, 2019 by telescoper

I’m taking a few days off at the moment so this morning I had a bit of time to catch up on various things. One news item I stumbled across points out that first-choice applications to study at Maynooth University are the highest ever. Within the overall increase of about 7% there is a growth of 17% in Science subjects, which is very good news for the Department of Theoretical Physics as well as the other Departments in the Faculty of Science and Engineering.

Anyway, this spurred me to comment on what I think is one of the strengths of Maynooth University: the Omnibus Science programme.

Currently, most students doing Science subjects here enter on the Omnibus programme, a four-year science course that involves doing four subjects in the first year, but becoming increasingly specialised thereafter. That’s not unlike the Natural Sciences course I did at Cambridge, except that students at Maynooth can do both Theoretical Physics and Experimental Physics in the first year as separate choices. Other possibilities include Chemistry, Computer Science, Biology, etc.

In Year 1 students do four subjects (one of which is Mathematics). That is narrowed down to three in Year 2 and two in Year 3. In their final year, students can stick with two subjects for a Joint Honours degree, or specialise in one, for Single Honours.

I like this programme because it does not force the students to choose a specialism before they have had a taste of the subject, and that it is flexible enough to accommodate Joint Honours qualifications in, e.g., Theoretical Physics and Mathematics. It also allows us to enrol students onto Physics degrees who have not done Physics as part of the Leaving Certificate.

I think it’s a strength that students take such a broad first year rather than locking themselves into one discipline from the start. Part of the reason is that I went to do my own degree at Cambridge expecting to end up specialising in Chemistry, but enjoyed the physics far more, eventually specialising in Theoretical Physics. I’m sure there were others who went the other way too!

One problem with the Omnibus Science programme is that the range of possible final qualifications is perhaps not as clearly advertised as it could be, so some clearer signposting would do no harm.

## R. I. P. Wolfgang Rindler (1924-2019)

Posted in Books, Talks and Reviews, Education, The Universe and Stuff with tags , , , , on March 5, 2019 by telescoper

A recent comment on this blog drew my attention to the sad news of the death, at the age of 94, of Wolfgang Rindler. He passed away almost a month ago, in fact, but I have only just heard. My condolences to his family, friends and colleagues.

Wolfgang Rindler was a physicist who specialized in relativity theory and especially its implications for cosmology. Among other things he is attributed with the first use of the phrase `Event Horizon‘ as well as elucidating the nature of horizons in general relativity, both in the context of black holes and in cosmology. I never met him personally but to me, and I think to many other people, Wolfgang Rindler will be familiar through his textbooks on relativity theory. I have two in my collection:

I bought the one on the right on recommendation when I was an undergraduate over thirty years ago and the other (shorter) one I acquired second-hand some years later. Both are still very widely used in undergraduate courses.
I found the first one then (as I do now) rather idiosyncratic in approach and notation but full of deep insights and extremely effective from a pedagogical point of view. I still recommend it to students, to balance more conventional modern texts which tend to be far more conventional. It’s no easy thing to write textbooks and Wolfgang Rindler deserves high praise for having devoted so much of his time, and considerable talent, into writing ones whose impact has been so widespread and lasted so long.

Rest in peace, Wolfgang Rindler (18th May 1924 – 8th February 2019).

## From Phase Walks to Undergraduate Research

Posted in Education, The Universe and Stuff with tags , , , , , on September 28, 2018 by telescoper

This week I put together a couple of brief descriptions for possible research projects for final-year undergraduate and/or Masters students in the Department of Theoretical Physics at Maynooth University, and I was reminded of the value of projects like this when I found this paper on the arXiv:

In fact the `Phase Walk Analysis’ developed here is based on an original idea I had for an undergraduate summer research project when I was at Nottingham University and have mentioned before on this blog. The student who did the project with me was Andrew Stannard (who is now at King’s College, London) and the work led to a paper that was published in a refereed journal in 2005 and has now been cited 21 times by various authors including the Planck Team.

Although Andrew is now working in a completely different area (Condensed Matter Physics), I like to think this taste of research was of at least some assistance in developing his career. Above all, though, it relates to something I read in the Times Higher by astronomer, Nobel Prize winner, and Vice-Chancellor of the Australian National University, namely that the idea that many politicians seem to have of separating teaching from research in universities is at best misguided and at worst threatens the very idea of a university.

## The Importance of Taking Notes

Posted in Biographical, Education with tags , , , on September 24, 2018 by telescoper

Well, term has officially started and the campus of Maynooth University is looking very busy. Taking a short break from the task of preparing notes and problem sets for the modules  I’m teaching this term.  I’ve just remembered 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 that many students are simply not used to taking notes and find it difficult to do so effectively during lectures, so much so that the effort of copying things onto paper must surely prevent them absorbing the intellectual content of the lecture (assuming that there is any). Since it’s the first week of teaching here, I thought I’d share some thoughts, for the benefit of those starting a new term.

I dealt with the problem  of taking notes 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 many 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 (and which actually works very well in mathematically-based disciplines). That’s probably because they get much less practice at school than my generation did. Most of my school education was done via the blackboard..

Nowadays,  many lecturers  give copies of their powerpoint slides to students and others even 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. In other words, entirely passive learning is unlikely to be effective.

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 completely as possible. I don’t mean by copying down what they see on the screen and what they may have on paper already, but by 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 modules I’m doing this term I don’t intend to 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.

As a further study aid, most lectures at my previous institutions (Sussex University and Cardiff University) are recorded and made available to students to view shortly after the event. Contrary to popular myth there’s no evidence that availability of recorded lectures lowers the attendance at lectures. It appears that students use the recordings for revision and/or to clarify points raised in the notes they have taken, and if anything the recordings allow the students to get greater value from lectures rather than persuading them that there’s no need to attend them. Unfortunately we don’t have lecture capture at Maynooth, but I hope it can be introduced  here at some point.

I do 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 only  option and ensure that a range of teaching methods is available.

I don’t think I ever learned very much about physics from lectures – I found problem-based learning far more effective – 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 in danger of becoming a dying art. If we’re going to carry on using lectures, we old fogeys need to stop assuming that students learnt it the way we did and start teaching it as a skill.

Perhaps the biggest problem with the way we* teach physics these days, however,  is not really about the mode of delivery but the compartmentalization that has crept in via the school system which encourages students to think of each `module’ as a bite-sized piece that can be retained until the examinations, regurgitated, and then forgotten. I’ve no doubt that a great many students pass the examinations we set by simply memorizing notes with little genuine understanding  needed or problem-solving ability demonstrated. We promote physics as a subject that nurtures these skills, but I don’t think many physics graduates – even those with good degrees – actually possess them at the end. We should be making much more of an effort in teaching students how to use their brains in other ways than as memory devices, and getting them engaged in more active teaching activities seems to me to be a very high priority. That said, I think we probably do much more of this in physics than in most other subjects!

*by `we’ I mean physicists generally, rather than my current Department (where we do actually make a lot of effort to develop these skills through small group sessions that complement other teaching activities.

## Age, Memory and Learning

Posted in Education, Maynooth with tags , , , , , , , on August 20, 2018 by telescoper

Today’s a big day for prospective students at Irish universities. It’s the day when the Central Applications Office (CAO, the equivalent of the UK’s UCAS) makes offers of places to students based the Leaving Certificate results that were announced last week. Thus begins the process by which universities find out how many students we will have for entry next month. Lectures here at Maynooth start on 24th September, with an induction week before that, so there promises to be quite a rush to get everything sorted out.

The first thing that struck me thinking ahead to this year’s new entry of students was that the majority of students starting this autumn either here in Ireland or in the UK were born in the year 2000. That means that I’ve been a Professor (at four different universities: Nottingham, Cardiff, Sussex and Maynooth) all the time they have been alive! Yikes I feel old!

The other thing that struck me among all the press coverage of the Leaving Certificate in Ireland is the significant amount of griping about how these examinations are basically just memory tests and the system encourages rote learning. This is something I’ve complained about before in the context of British A-levels and indeed the system of university examinations.

Over my lifetime the ratio of assessment to education has risen sharply, with the undeniable result that academic standards have fallen especially in my own discipline of physics. The modular system encourages students to think of modules as little bit-sized bits of education to be consumed and then forgotten. Instead of learning to rely on their brains to solve problems, students tend to approach learning by memorizing chunks of their notes and regurgitating them in the exam. I find it very sad when students ask me what derivations they should memorize to prepare for examinations because that seems to imply that they think their brain is no more than a memory device. It has become very clear to me over the years that school education in the UK does not do enough to encourage students to develop their all-round intellectual potential, which means that very few have confidence in their ability to do anything other than remember things. It seems the same malaise affects the Irish system too.

On the other hand, as a number of people have pointed out in opinion pieces (e.g. here) and letters (here and here), a good memory is undoubtedly an extremely important asset in its own right.

I went to a traditional Grammar school that I feel provided me with a very good education in which rote learning played a significant part. Learning vocabulary and grammar was an essential part of their approach to foreign languages, for example. How can one learn Latin without knowing the correct declensions for nouns and conjugations for verbs? But although these basic elements are necessary, however, they are not sufficient. You other aspects of your mental capacity to comprehend, translate or compose meaningful pieces of text.

The same considerations apply to STEM disciplines. It is important to have a basic knowledge of the essential elements of mathematics and physics as a grounding, but you also need to develop the skill to apply these in unusual settings. I also think it’s simplistic to think of memory and creative intelligence as entirely separate things. I seems to me that the latter feeds off the former in a very complex way. A good memory does give you rapid access to information, which means you can do many things more quickly than if you had to keep looking stuff up, but I think there’s a lot more to it than that. Our memories are an essential part of the overall functioning of our brain, which is not  compartmentalized in such a simple way.  For example, one aspect of problem-solving skill relies on the ability to see hidden connections; the brain’s own filing system plays a key role in this.

Recognizing the importance of memory is not to say that rote learning is necessarily the best way to develop the relevant skills. My own powers of recall are not great – and are certainly not improving with age – but I find I can remember things much better if I find them interesting and/or if I can see the point of remembering them. Remembering things because they’re memorably is far easier than remembering because you need to remember them to pass an examination!

Posted in Education with tags , , , , on August 15, 2018 by telescoper

Today’s the day in Ireland that students get the results of their school Leaving Certificate examinations and, over the other side of the Irish Sea, tomorrow is when A-level results come out. For many there will be joy at their success, and I particularly look forward to meeting those who made their grades to get into Maynooth University shortly.

Others will no doubt receive some disappointing news.

For those of you who didn’t get the grades you needed or expected, I have one piece of very clear advice:

In particular, if you didn’t get the Leaving Certificate points you needed for entry to your first University in Ireland or the A-levels needed to do likewise in the United Kingdom, do not despair. There are always options.

For example, in Ireland, you could try looking at alternative choices on the Available Courses, where any places remaining unfilled in particular courses after all offers have been made and the waiting lists of applicants meeting minimum entry requirements have been exhausted, will be advertised.

In the United Kingdom the Clearing system will kick into operation this week. It’s very well organized and student-friendly, so give it a go if you didn’t make your offer.

Posted in Cardiff, Education, Maynooth with tags , , , on May 25, 2018 by telescoper

I’m currently waiting for the last couple of scripts from my Physics of the Early Universe examination to arrive so I can begin the task of marking them. The examination was yesterday morning, and it’s now Friday afternoon, so I don’t know why it takes so long for the scripts to find their way to the examiner, especially when marking is on such a tight schedule. I’m away next week (in Ireland) so if I don’t get papers by this afternoon they won’t be marked until I return. The missing two are from students sitting in alternative venues, but I don’t see why that means they take over 24 hours  to get to the marker.

(By the way,  `script’ refers to what the student writes (usually in a special answer book), as opposed to the `paper’ which is the list of questions to be answered or problems to be solved in the script.)

Anyway, while I’m waiting for the missing scripts to arrive I thought I’d mention that here in the School of Physics & Astronomy at Cardiff University we have a system whereby students can get access to their marked examination scripts.  This access is limited, and for the purpose of getting feedback on where they went wrong, not for trying to argue for extra marks. The students can’t take the scripts away, nor can they make a copy, but the can take notes which will hopefully help them in future assessments. There’s a similar provision in place in the Department of Theoretical Physics at Maynooth University, where I will be relocating full-time in July, based around a so-called `Consultation Day’.

When I was Head of the School of Mathematical and Physical Sciences at Sussex University I tried to introduce such a system there, but it was met with some resistance from staff who thought this would not only cause a big increase in workload and but also lead to  difficulties with students demanding their marks be increased. That has never been the experience here at Cardiff: only a handful take up the opportunity and those that do are told quite clearly that the mark cannot be changed.  Last year I had only one student who asked to go through their script. I was happy to oblige and we had a friendly and (I think) productive meeting.

If I had my way we would actually give all students their marked examination scripts back as a matter of routine. The fact that we don’t is no doubt one reason for relatively poor performance in student satisfaction surveys about assessment and feedback. Obviously examination scripts have to go through a pretty strict quality assurance process involving the whole paraphernalia of examination boards (including external examiners), so the scripts can’t be given back immediately but once that process is complete there doesn’t seem to me any reason why we shouldn’t give their work, together with any feedback written on it,  back to the students in its entirety.

I have heard some people argue that under the provisions of the Data Protection Act students have a legal right to see what’s written on the scripts – as that constitutes part of their student record – but that’s not my point here. My point is purely educational, based on the benefit to the student’s learning experience.

Anyway, I don’t know how widespread the practice is of giving examination scripts back to students so let me conduct a totally unscientific poll. Obviously most of my readers are in physics and astronomy, but I invite anyone in any academic discipline to vote:

And, of course, if you have any further comments to make please feel free to make them through the box below!

## When Log Tables aren’t Log Tables

Posted in Education, mathematics, Maynooth with tags , , , , , on May 17, 2018 by telescoper

Every now and then – actually more frequently than that – I reveal myself in Ireland as an ignorant foreigner. The other day some students were going through a past examination paper (from 2014) and I was surprised to see that the front cover (above) mentioned  `log tables’.

Now I’m old enough to remember using tables of logarithms (and other mathematical tables  of such things as square roots and trigonometric functions, in the form of lists of numbers) extensively at school. These were provided in this book of four-figure tables (which can now buy for 1p on Amazon, plus p&p).

As a historical note I’ll point out that I was in the first year at my school that progressed to calculators rather than slide rules (in the third year) so I was never taught how to use the former. My set of four-figure tables which was so heavily used that it was falling to bits anyway, never got much use after that and I threw it out when I went to university despite the fact that I’m a notorious hoarder.

Anyway, assuming that the mention of `log tables’ was a relic of many years past, I said to the group of students going through the old examination paper that it seemed somewhat anachronistic. I was promptly corrected, and told that `log tables’ are in regular use in schools and colleges throughout Ireland, but that the term is a shorthand for a booklet containing a general collection of mathematical formulae, scientific data and other bits of stuff that might come in useful to students; for an example appropriate to the Irish Leaving Certificate, see here. One thing that they don’t contain is a table of logarithms…

Students in Physics & Astronomy at Cardiff University are also given a formula booklet for use during examinations. I don’t remember having access to such a thing as an undergraduate, but I don’t object to it. It seems to me that an examination shouldn’t be a memory test, and giving students the basic formulae as a starting point if anything allows the examiner to concentrate on testing what matters much more, i.e. the ability to formulate and solve a problem. The greatest challenge of science education at University level is, in my opinion, convincing students that their brain is much more than a memory device…