Tag Archives: Third level

Resistors in series and parallel

In the last post, we saw that for many materials, the electric current I through a device is proportional to the voltage V applied to it, and inversely proportional its resistance, i.e. I = V/R (Ohm’s law). If there is more than one device (or resistor) in a circuit, the current through each also depends on how the resistors are connected, i.e., whether they are connected in series or in parallel.

In a series circuit (below), the resistors are connected one after the other (just as in a TV series, one watches one episode after another). The same current runs through each device since there is no alternative path or branch, i.e.  I = I1 = I2. From V = IR, we see the voltage across each device will be different; in fact, the largest voltage drop will be across the largest resistance (just as the largest energy drop occurs across the largest waterfall in a river). The total voltage in a series circuit is the sum of the individual voltages, i.e. V = V1+V2. As you might expect, the total resistance (or load) of the circuit is the simply the sum of the individual resistances, R = R1 + R2.

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Series circuit: the current is the same in each lamp while there may be a different voltage drop across each (V = V1+V2 +V3)

On the other hand, resistors in a circuit can be connected in parallel (see below). In this case, each device is connected directly to the terminals of the voltage source and therefore experiences the same voltage (V = V1=V2). Since I = V/R , there will be a different current through each device (unless they happen to be of equal resistance) .The total current in a parallel circuit is the sum of the individual currents, i.e. I = I1+I2. A strange aspect of parallel circuits is that the total resistance of the circuit is lowered as you add in more devices (1/R = 1/r1 + 1/r2). The physical reason is that you are increasing the number of alternate paths the current can take.

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Parallel circuit: the voltage is the same across each lamp but the currents may be different (I = I1+I2)

Confusing? The simple rule is that in a series circuit, the current is everywhere the same because there are no branches. On the other hand, devices connected in parallel see an identical voltage. In everyday circuits, electrical devices such as kettles, TVs and computers are connected in parallel to each other because it is safer if each device sees the same voltage source; it also turns out to be more efficient from the point of view of power consumption (an AC voltage is used, more on this later).

In the lab, circuits often contain some devices connected in series, others in parallel. In order to calculate the current through a given device, redraw the circuit with any resistors in parallel replaced with the equivalent resistance in series, and analyse the resulting series circuit.

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Problem

Assuming a resistance of 100 Ohms for each of the resistors in the combination circuit above, calculate the total resistance of the circuit. If a DC voltage of 12 V is applied, calculate the current in the circuit. (Ans: 133 Ω, 0.09 A)

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Current, voltage and the French resistance

Last week, our 1st science students had their first laboratory session on electrical circuits. They haven’t met electricity in lectures yet, so I spent some time explaining the concepts of current and voltage.

In essence, current is the flow of electric charge around a circuit (measured in amps) while voltage is the energy that drives the current (and is measured in volts). I find it helpful to think of the two in terms of cause and effect; a current will only flow in the circuit if a voltage is applied. In simple circuits, this energy is supplied in the form of a DC battery (or voltage source) that drives the current through some device (or resistor) in the circuit.

Let's Explore Science... Turn on the Light

The lamp (or resistor) lights as the current goes through it, completing the circuit

You might expect that there is a simple relation between voltage and current, and sure enough, the German scientist Georg Ohm discovered that, for many materials, there is a linear relationship between the two. Ohm’s law states that the current I passing through a material connected to a voltage V is given by the simple equation I = V/R. Here, 1/R is the constant of proportionality and is called electrical resistance and you can see why from the equation: a material with a very large value of R will pass almost no current (bad conductor), while a material with very small R will yield a large current for the same voltage (good conductor). So the term has exactly the same meaning as it has in ordinary speech, e.g. the French resistance. Resistance is measured in volts per amp, also known as Ohms (Ω).

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Many materials have a linear relation between voltage and current – the slope of the graph is the material’s resistance

In the experiment, the students apply a series of voltages to an unknown resistance in a circuit, and record the corresponding currents. A plot of voltage versus current then allows them to verify the linearity of the relation and the resistance is estimated from the slope of the line. (Strictly speaking, one should really put the voltage on the x-axis as it is the independent variable, but the calculation is simpler if the voltage is on the y-axis).

Measuring current and voltage

All of the above is fine in principle. Yet novices find the measurements quite difficult in practice. They have problems connecting the circuit because they get confused between measuring the current that flows through a device, and the voltage across it. It’s crucial to understand the difference between the two, and I suspect the modern multimeter adds to the confusion.

simple-circuit-diagram

The ammeter reads the current running through the resistor while the voltmeter reads the voltage across it. A plot of voltage vs current gives a measurement of the resistance

When I was a student, the current was measured by passing the current through an ammeter (marked A in the diagram), an analog device with a nice big dial calibrated in amps or milliamps. The voltage across the resistor was measured by connecting a different instrument, the voltmeter, across the terminals of the resistor; this voltmeter was a separate meter with a dial calibrated in volts (marked V in the diagram). So an ammeter was always connected in series with the resistor/device, while the voltmeter was always connected across it (in parallel).

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Current is measured by passing it through the ammeter (L) while voltage is measured by connecting across the voltmeter (R)

Nowadays, identical instruments are used for both; to measure current, one passes the current through the terminals marked ‘current’ of a multimeter, and the main dial on the meter is switched to the amp scale. To measure voltage, one connects the ends of the resistor across the terminals marked ‘voltage’ on an identical multimeter, and the dial is switched to volts. It sounds simple, but it’s easy to connect to the wrong terminals, getting no readings or blowing the fuse in the meter. More subtly, I think the clever circuity inside the multimeter hides the fact that current goes through while voltage drops across. All in all, I suspect students would understand circuits better if  we went back to separate instruments for measuring current and voltage….

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The mysterious multimeter. To measure current, leads are connected to the sockets marked ‘common’ and ‘amps’; to measure voltage, one connects to the sockets marked ‘common’ and ‘voltage’.

Notes

1. If a 12-V voltage is applied across a resistor of 15, what current flows in the circuit? How many electrons per second does this current represent? (Ans: 0.8 mA,  5.0 x 1015 electrons)

2. What happens to the current if one end of the resistor accidentally touches the other? (Ans: the circuit resistance drops almost to zero and the current becomes very large – don’t try this in the lab!)

3. Ohm’s law is a misnomer – it is not a universal law of nature but simply a property of some materials (many materials have a nonlinear response to voltage, including your cat).

4. It might seem from Ohm’s law that a material with zero resistance can give infinite current! No such materials are known; the relation is simply not valid for these materials. However, some materials have extremely low resistance at very low temperatures, known as superconductors. A good application of superconductivity can be found at the Large Hadron Collider, where protons are guided around the ring by magnets made of superconducting material: this reduces power consumption enormously but the snag is that the entire accelerator has to be kept at extremely low temperatures during the experiments.

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RTE, NASA and a WARP drive

On Friday, I got a call from Mooney Goes Wild , the daily science programme on Irish national radio, asking me to participate in an interview concerning NASA’s recent interest in creating a WARP drive for space travel. I’d heard this interesting story over Christmas and I like science on the radio, so it was fun to look up a few details and take part in the discussion.

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Starship Enterprise of Star Trek uses a warp drive to traverse the immense distances of outer space

The live interview took place that very afternoon, right in the middle of our College Exam Boards (those weighty meetings when lecturers come together with external examiners to decide which students pass and which don’t). Our current physics extern, Professor Peter Mitchell of UCD, taught me as a student, so we had fun discussing the NASA project over lunch.

In the event, the interview was very interesting; I thought the RTE panel of Olan Mc Gowan, Eanna ni Lamhna, Richard Collins and Terry Flanagan asked great questions and we all enjoyed ourselves. Below is the Q&A script I prepared in advance (I always run up a draft script as it helps me organize my thoughts and it provides interviewers with a jumping-off point). The panel’s questions went a good deal further, you can hear a podcast of the interview here.

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Artist’s impression of the NASA experiment; the vacuum ring causes space behind the object to expand, propelling it forwards

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Script

We recently came across a story that NASA has begun work on the development of a WARP drive, a device that would allow spaceships to travel faster than light. Such an engine could in principle transport a spacecraft to the most distant stars in a matter of weeks, but seems the stuff of science fiction.  We contacted Dr Cormac O Raifeartaigh, a physicist at Waterford Institute of Technology, to get his opinion on this story…

PANEL: First of all, what is a warp drive?

 COR: It’s the word used for a hypothetical engine that could drive a spacecraft by distorting or ‘warping’ space. In principle, this could allow  the ship to travel faster than the speed of light, taking a shortcut to reach remote galaxies in hours instead of millions of years! (The device turns up in science fiction in order to enable people to get from one galaxy to another without dying of old age on the way…even travelling to a nearby planet  takes several years).

PANEL: How is it supposed to work? I thought faster-than-light travel was supposed to be impossible?

COR: That’s right. According to Einstein’s theory of relativity, no material body can reach the speed of light. If it comes close to this speed, the body gets bigger, and heavier, and it cannot match the speed of something with no mass (light). There is a lot of evidence to suggest that this is exactly what happens, it’s amazing to see particles like  protons accelerated at facilities like the Large Hadron Collider  up to speeds like 99.99% of the speed of light, but never quite reaching nature’s speed limit.

PANEL: So, how does the warp drive work then ?

 COR: Another prediction of relativity is that space and time are not fixed, but affected by motion and by gravity. For example, there is a huge amount of evidence that the space of our universe is continually expanding. In principle, a patch of space can move at any speed; if you could somehow  warp a bubble of space around an object ( or spaceship), then that object would travel at the speed set by the distortion..

PANEL: Has this mad idea been around for a while?

COR: Yes,in principle. The problem is that the energy required to make that bubble of warped space is far greater than any energy available. What’s new is that physicist Harold White at NASA thinks he can reduce the energy required, with a clever design; the object (spaceship) is surrounded by a thin vacuum ring of a special shape that causes the space just behind the spaceship to expand, and just in front to contract; the difference propels the spaceship very fast indeed! Of course that’s just the theory..

PANEL: Do you think it will work?

COR: No, I doubt it, even with objects on the atomic scale. However, we will learn a lot by trying, there’s nothing wrong with the principle. For example,  many cosmologists believe that our whole universe expanded at speeds far greater than light during the first instant (the theory of cosmic inflation), before settling down to today’s more sedate expansion. But as regards investment, I wouldn’t put any money in ‘warp drive’ shares just yet!

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End of semester

This week is one of my favourites in the college timetable. The teaching semester finished last Friday and the hapless students are now starting their Christmas exams. It’s time to empty out the teaching briefcase and catch up on research…

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Examtime in college

I recently compiled a list of this semseter’s research and outreach and was pleasantly surprised – three conference presentations, two academic papers and eight public lectures , not to mention a couple of science articles and book reviews in The Irish Times (see here for presentations and here for articles).

All of this is on top of an 18-hour teaching week, which adds up to a lot of late nights. I’ve been arguing for years that the workload in the Institutes of Technology should be more flexible; it’s very difficult to do any meaningful research if you’re teaching 18 hours a week. Another challenge is that most lecturers in the IoT sector are 3-4 to an office, with consequent staff interactions, phone calls and students coming to the door. As a result, a great many lecturers simply stop doing research, which is a terrible waste and hardly ideal for a college that teaches to degree level and beyond. I often think that, far from enhancing ‘productivity’, work practices in the IoT sector mitigate strongly against good teaching and research at third level.

In my case, I stay in college most evenings until 9 pm. That said, I enjoy the research – as I say to my students, if you find a job you truly like, you’ll never work a day in your life!

I’m particularly pleased with my recent paper on the discovery of the expanding universe. It’s my first foray into the history of cosmology, and it has already got quite a bit of attention,  thanks to a very nice conference in Arizona. I very nearly didn’t go to this conference because of teaching commitments; now I’m glad I did as it was a lot of fun and the paper has opened quite a few doors. These days, I turn down far more opportunities than I accept, it may finally be time to consider an academic move.

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Slipher’s telescope at the Lowell Observatory in Flagstaff, Arizona

Update

Meanwhile, rumours continue to circulate in the media concerning the prospect of our college being turned into a technological university. This would certainly be a welcome development, especially if it meant reduced teaching for those engaged in research, but I’d be quite surprised. WIT has been very successful at attracting research funding in certain areas, but research activity per academic is quite low in our college in comparison with the university sector. I don’t see how we could qualify as a university without bringing in quite a lot of new research-active staff , a buy-in for which there is no money whatsoever; hopefully I’m wrong on this.

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Mozart and the stars

I had a lovely evening on Thursday playing Mozart piano trios in Castalia Hall in Ballytobin, Co. Kilkenny. My fiddle doesn’t come out of retirement that often these days but I always try and make an exception for chamber music, especially if it’s Mozart. (Note: a piano trio means a piano, violin and cello playing together, not three pianos!)

Castalia hall, Ballytobin

The hall was a big surprise; tucked away at the foot of a large property belonging to the Camphill community of Ballytobin, it is a beautiful building, highly original in style and with a fantastic acoustic. The Camphill community was set up as a therapeutic centre for children and adults with physical or mental disabilities and there is a really nice atmosphere there. Several of the young guests wandered into the hall while we were playing, clearly well used to visiting musicians.

And what musicians. One of the great advantages of teaching at Waterford Institute of Technology is that I occasionally get to play music with renowned harpsichordist Malcolm Proud. Malcolm lectures in music in our college and just happens to be a world authority on period music. When he’s not away on solo recitals around Europe or touring with the Irish Baroque Orchestra, he likes to relax by playing chamber music of a different era – which is where amateurs like me come in.

Malcolm at the piano at Castalia hall

Of course, I’m not the only violin-playing physicist, it’s well-known that Einstein played the violin to to quite a serious level. Actually, an extraordinary number of mathematicians and physicists play classical music, I’ve often wondered about the connection. It’s hard to judge just how good a player Einstein was from his biographers; however, he must have ben reasonably competent as he performed celebrity chamber concerts with outstanding musicians such as Rubenstein. I read somewhere that Mozart was his favourite composer, that’s something else we have in common.

Einstein in concert with a piano trio

On Thursday, we played through the G major (K496) and C major  (K548) trios. Although I have played the piano quartets many times, the trios were new territory for me.  Looking at the score in advance, I thought the C major would be the more challenging of the two – in fact it was absolutely beautiful to play, a lovely opening movement followed by a fantastic slow movement. Another Mozart discovery, can’t wait to try the other five trios.

After the session, we climbed up the tower at Castalia to inspect the new observatory. John Clarke, the director of the community, had the tower built with a view to mounting a telescope on top; he has done a fantastic job, it’s a superb location for an observatory. Then we all went back to Malcolm’s house to inspect a telescope that has been misbehaving. Our cellist Ian McShane is a keen astronomer and it took him about three minutes to find the problem , whereupon we all had a good look at the beautiful night sky one sees on clear nights in rural Ireland.

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September conference: origins of the expanding universe

A conference next month will celebrate the pioneering work of the American astronomer Vesto Slipher. On September 13-15th, the Lowell Observatory in Flagstaff, Arizona, will host the conference The Origins of the Expanding Universe to commemmorate the hundredth anniversary of Slipher’s measurements of the motion of the distant nebulae; see here for the conference website.

As readers of this blog will know, Slipher observed that the light from many of the distant nebulae was redshifted, i.e. shifted to lower frequency than normal. This was the first  indication that the distant nebulae are moving away at significant speed and it was an important hint that some nebulae are in fact distinct galaxies far beyond our own Milky Way (see cosmology 101 section). A few years later, Edwin Hubble combined Slipher’s redshift results with his own measurements of distance to establish that there is a linear relation between the distance to a galaxy and its rate of recession; the relation became known as Hubble’s law although it probably should be called the Hubble/Slipher law.

The Hubble/Slipher discovery of the recession of the galaxies  was a key step along the road to the discovery of the expanding universe, but the two are not quite the same thing; for the latter, one needs to situate the phenomenon in the context of the general theory of relativity (according to relativity, the galaxies appear to be moving away from one another because space is expanding). The Belgian physicist Georges Lemaitre was the first to make the connection between the relativistic universe and the observed recession of the galaxies, although his contribution is often overlooked. A major thrust of the conference is to explore exactly such distinctions; looking at the lineup, it looks like an intriguing mixture of cosmologists, astronomers and historians.

All this is highly relevant to my yet-to-be-completed book so after a long, wet summer at WIT, I’m off to sunny Arizona next month!  My own talk is titled ‘Who discovered the expanding universe?’ and I intend to compare and contrast the contributions of various pioneers such as Slipher, Hubble, Humason, Friedmann and Lemaitre. You can see a list of speakers and abstracts for the talks here.

Many thanks to Peter Coles of In the Dark for drawing the conference to my attention.

Update

Going on holiday just as classes start back? Nice job – Ed.

Sigh. I haven’t had a day off all summer and this is not a holiday.

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O’Raifeartaigh Conference in Munich

I’m in Munich this weekend, at a physics conference in honour of my late father. The 2012 O’Raifeartaigh Conference is taking place in Munich’s Ludwig Maximilians Universität (LMU) and there are speakers here from Harvard, MIT, Stanford, the University of Tokyo, the Niels Bohr Institute (DK), the Eugene Wigner Institute (HN) and the Dublin Institute for Advanced Studies.

It sounds rather grand, but such memorial conferences are a good way for researchers who work in related fields to meet and present their latest work to each other. Many of the speakers worked with Dad at one stage or another and I think he would be very pleased to be remembered in this way. There are also some really sharp young scholars here and he would have liked that too. It’s the third memorial conference in Lochlainn’s memory, see here for the programme and other details.

Munich itself is fantastic – the university is right in the middle of the city and the neighbourhood is full of bookshops, coffee-houses, museums and beer gardens. The teaching term is not yet finished in Germany so there are students everywhere (don’t tell Minister Quinn!). In fact, I have never seen so many bicycles and bookshops in one place. The conference talks are in the University’s Arnold –Sommerfeld Centre for Theoretical Physics and the building has a Museum for Modern Art on one side and a music conservatoire or Musik Hochshule down the block. I could get used to this.

LMU University Munich (Main Entrance)

Lochlainn’s work concerned the use of mathematical symmetry methods to describe the physics of the elementary particles. Throughout his career at the Dublin Institute for Advanced Studies, he was considered a leading expert in the field. He is probably best known for his contributions to a radical theory known as ‘supersymmetry’, a theory that is currently being tested at the Large Hadron Collider at CERN. You can read more on his career by clicking on the tab Lochlainn on the top of the page.

There are some great talks here although some are are far beyond the comprehension of yours truly (an experimentalist). As always, I’m impressed by the style of presentation in theoretical physics; there are no polite powerpoint lectures here, but chalk-and-blackboard sessions with searching questions from the audience every few minutes. ‘‘Does that function even have a ground state?’, a speaker was asked within the first two minutes of his talk. ‘‘Well, it doesn’t in anti-deSitter space, but I hope to convince you that it does in deSitter space”, was the response. Answers to the frequent questions are tackled at the board until everyone in the room is satisfied. No-one gets away with anything here, from the youngest postdoc to the most eminent physicist. I think it’s a style of presentation that helps both lecturer and audience and I wish the humanities would adopt it – my pet hate is listening politely to a philosopher or historian for an hour before one gets to question a statement made in the first three minutes.

I gave a short talk myself on Friday. This was a ‘life-in-science’ presentation where I used pictures of people and places that influenced Lochlainn during his career: from his early work on general relativity with JL Synge  at the Dublin Institute for Advances Studies to his work on quantum field theory with Walter Heitler at the University of Zurich, from his use of group theory to prove his famous no-go theorem at Syracuse University in New York State to his work on the history of gauge theory at L’Institut des Hautes Etudes in Paris. I was worried I might have got some things wrong (e.g. “No, that work was completely incidental!’’), but thankfully it didn’t happen. In fact, I think the audience enjoyed the presentation as many of them had known the people and places mentioned at firsthand. You can find the photos and slides I used here.

Update

The conference is over today so Mum and I took an open bus tour of Munich. I find this a great way to get to know any city and it didn’t disappoint. Munich may not be as large as Berlin or Hamburg, but it is the capital of Bavaria and is an extremely impressive city. I’m amazed by the huge number of parks, wide boulevards and splendid buildings – clearly, it was did not suffer as much as so many other German cities from bombing in the war. This is one of the great privileges of being an academic – you get to see the most interesting places, all in the line of work.

The ‘heroes’ monument on Leopoldstrasse

And finally

On the way back to the hotel, I was intrigued to see a huge banner draped over the main university entrance; the legend’ STRINGS 2012′ is leaving the whole city in no doubt that a major conference on string theory is about to take place here! Such a civilised country..

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Schrödinger, Heuer, the Higgs boson and a European science festival in Dublin

Last week, I attended the ESOF science meeting in Dublin. The Euroscience Open Forum is a science festival held in a European city every two years; Dublin won the contract for 2012 (and built a year-long science festival around it, see here for details of the Dublin City of Science).  The stated aims of ESOF conferences are

  • to showcase the latest advances in science and technology
  • to promote a dialogue on the role of science and technology in society
  • to stimulate and provoke public interest in science and technology

I think the Dublin meeting achieved these aims in spades. It was a superb conference with a large number of interesting events, from top-level keynote talks (speakers included 5 Noble laureates) to smaller interactive seminars. The main venue was also a pleasant surprise -a beautiful light -filled and airy convention centre with a multitude of auditoria, lecture theatres and smaller conference rooms.

The new convention centre in Dublin, the main venue for ESOF 2012

One of the most interest events was ‘What is Life?- A 21st Century Perspective‘, presented at Trinity College Dublin by the Royal Irish Academy. This was a revisiting of the famous public lectures given by Schrödinger in Dublin in 1942 during his tenure at the Dublin Institute of Advanced Studies. Craig Venter, celebrated for his contribution to the sequencing of the human genome, gave an overview of Schrodinger’s influence on the work of Crick and Watson in their search for the structure of DNA, and how their work led in turn to the modern science of genetics and genomics. Even the booklet accompanying the lecture contained some fascinating information, from a superb account of Schrödinger’s life and career (by Prof Luke Drury of the Dublin Institute for Advanced Studies), to a copy of a letter from Francis Crick to Schrödinger thanking him for his inspiration!

Craig Venter

For physicists, the big event was a lecture by Rolf-Dieter Heuer, director-general of CERN, on the recent discovery of a Higgs-like particle at the Large Hadron Collider. This was quite a coup for Dublin as it was one of Heuer’s first public lectures since the landmark discovery. In fact, he took part in three events; an evening lecture at Trinity College Dublin (hosted by Astronomy Ireland), a Q&A workshop at the Royal Irish Academy and a keynote lecture at the conference centre. All the events were packed out and deservedly so. It is not an easy task to explain almost a century of particle physics in 45 minutes, yet Heuer does it time and again with ease, whilst simultaneously conveying the excitement of the experimental work at the Large Hadron Collider. His constant emphasis on the teamwork of experimentalists, engineers and analysts gives a direct view of just why this unique inter-european project has become the NASA of the particle world. (He has a great quote on the work of the giant detectors: “it’s like looking for a needle in a field of haystacks, all made of similar needles”). Last but not least, Prof Heuer took the time to draw a connection with the groundbreaking accelerator work of the Irish physicist Ernest Walton, a connection that is often forgotten when the LHC is discussed in Ireland.

Profess0r Rolf-Dieter Heuer, DG of CERN, in Dublin at ESOF 2012

There were many other great events; Brian Greene’s lecture ‘The State of String Theory‘ was a superb performace, I don’t know another scientist who puts on quite such a show. Other highlights were Jocelyn Bell’s ‘We are made of star stuff’ and Lisa Randall’s ‘High Energies and Short Distances’. Truly, an embarrassment of riches. If you like a strong mix of brilliant physics and clear philosophy of science, get Lisa’s fabulous new book Knocking on Heaven’s Door. On a different theme, President Robinson’s lecture ‘Equity and climate science‘ described how climate change will impact on the poorest nations of the world, and reminded every scientist in the room of one of the most important scientific issues of all.

Like all conferences, the networking was almost the best part; I met colleagues I haven’t seen since my undergraduate days, not to mention a great many of my former professors. This is the real importance of such events; it’s very interesting discussing the latest developments in science with one’s former teachers! All in all, it was a superb conference for anyone with an interest in science and I hope to attend the next meeting in Copenhagen in 2014.

Taking a break with Peter Mctchell of UCD (who taught me low-temperature physics) and Lisa Randall, the Harvard string theorist

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You must be on your holidays now

You must be on your holidays now? I’m confronted with this question/accusation every time I go shopping in my village these days. Almost everyone I know assumes that lecturers merely teach and the summer holidays are ours to enjoy at our leisure.

I never know how to correct this misapprehension. Usually, I just nod amiably – after all, the main thing is that I have a job I really enjoy doing. However, it worries me that there is such widespread misunderstanding of academia. Occasionally, I try to explain that ‘holiday-time’ is in fact the only time I get to do any research. However, I usually get the feeling the questioner either doesn’t believe me or thinks I’m a fool for not putting our generous holidays to good use.

And the official holidays are generous, there’s no question. In the Institutes of Technology, staff do not have to report formally for work from June 20th to September 1st. It sounds great, doesn’t it? But for those engaged in research at any level (and it’s very difficult to get a job teaching to degree or master’s level if you are not engaged in some sort of research), this is the only time such work gets done.

In my case, I used to head back to my alma mater Trinity College as soon as term ended, doing experimental work in the magnetic resonance lab. These days, I’m more involved in writing science. This summer, I’m working on a book on cosmology, aimed at a popular audience. I started it last summer at Harvard and have been tipping away whenever I can during a very busy semester. Now I have a good opportunity to finish. I don’t think of this as a chore; like most academics, I see this sort of work as an important part of my job and it’s very satisfying. I really like working in the college over the summer months, it’s a very nice environment of quiet academic activity.

I also have two conferences in August and next month I’m giving a public talk on Irish astronomy and the big bang. So it’ll be a busy summer, which doesn’t bother me in the slightest as long as I get away for the odd weekend. As for travel, I’m coming round to the view that most countries are simply too hot for me in the summer and I like the variability of Irish weather. I’ll take a few weekends in the west coast of Ireland, playing tunes in the pubs at night and surfing during the day, that’ll do nicely…

It’s a tough life – Ed

Update

This blog has been nominated for an award, the Three Quarks Daily 2012 Awards. If you like the blog, why not throw in a vote here.  That said, there are some great blogs on the nominee page, I’m having fun browsing them all

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Exam corrections

I’ve just finished correcting the last exam script of summer 2012.  No more corrections until August, yipee. That said, I don’t really mind correcting the semester exams, unlike most of my colleagues. One reason is that I see it as a form of feedback, if pretty shocking sometimes!

Oh joy

It’s probably true that correcting maths or physics exams is somewhat easier than fighting your way through hundreds of poorly-written essays. (I suspect it’s also less depressing – I often think the standard of literacy amongst our students is more worrying than their lack of mathematical ability). By the time I have corrected the first ten physics scripts of any course, I have usually committed every possible answer to memory, so the job goes quite quickly. Also,  I like a task that has a definite beginning, middle and end with room for targets and treats along the way…

In our college, exam scripts are corrected by name and the students sometimes campaign for anonymous marking. Little do they know that from a teacher’s perspective, it’s much harder to fail a person than a number, particularly if you know that student made a decent effort during the semester. Indeed, a great deal of correction time goes into trying to trying to find a few extra marks for the borderliners; if anything, I would expect pass marks to drop if anonymous marking was introduced.

The main downside of examinations is the administration. Combining exam results with attendance and continuous assessment marks, and getting the totals to the department in time for the course board meetings is no trivial task if one is teaching several different courses . Worse, there are always one or two students who seem to have appeared out of nowhere, with an ensuing search for their educational record and assessment results.

By the end of this week, the innumerable departmental meetings will be over, and we will be ready to meet the externs next week. After all that, the results become official and I will finally, finally get back to research…


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