Dan, Dan the Physics Man

March 28, 2014 1 comment

I was very sad to hear this week about the death of my old high school physics teacher, Mr Livingston. I had him for five of my six years at school, and for all four years of my formal physics courses. It made me consider how important school and how especially important teachers are in getting us where to end up as adults, and it’s clear to me that without Mr Livingston’s influence there’s a good chance that I’d be (whisper it) a chemist…He was not the easiest teacher to get along with, being rather strict, and made of my classmates would probably say he turned them away from physics rather than on to it, but the fact that he really knew what he was talking about, and was able to communicate that understanding made him, in my eyes at least, one of the good ones. He was one of those teachers who was easily distracted. If he was asked the right sort of questions (often nothing to do with science) he would digress, often for a whole lesson, and it meant we often were very behind were we were meant to be. His stories about random things in physics stay with me even now, and I pass them on to my students and school kids in outreach events. The fact that cat fur used to be a mainstay in electrostatics experiments; the idea that you could learn which way German bombers were flying by listing to their engine noise; how to draw near perfect circles on a blackboard without any instruments; and of course the days when school kids were encouraged by teachers to bring in their fathers’ airguns for school experiments. I have lots of fond memories of classroom demos, and being closeted in his cupboard for my final year CSYS lessons. He was a great teacher, and I owe him a lot. May he rest in peace.

Categories: physics, schools Tags: ,

Media Interactions

This week I have a “News and Views” article published in Nature, which is a discussion of a research paper published in Physical Review Letters outlining an experiment in which a a mirror made from colloidal particles was trapped using laser beams. The idea is that this could be extended to much larger scale devices suitable for making space mirrors, for things like telescopes. Interestingly this article that I wrote about in Nature was then picked up by Physics Todayin a sort of degrees of separation from the original work game. I’m not quite sure what this tells me, other than the media is a bit different from academia – it’s rather faster paced, it scavenges material from where it can, and that I have the utmost respect for media people who can write quality material over a vast range of subjects with rapid turnaround times. I like writing stuff, but quick and accurate is not always my strong point (note the length of time since my last blogpost), but the communication of what we, scientists, do is really important. I’m glad that it is not always down to those at the coalface do that communication.

Note if you have comments on my article you can leave them at the bottom of the Nature page.

Going on a summer holiday, quantum style

The Academic Summer is an oft discussed thing. There are usually two camps, the outraged non-academic, moaning about taxpayers money going to fund four months of time off for lazy academics to swan about and not teach anybody anything, and the aghast academic bemoaning the fact that they work bloody hard thank you very much during the summer, and barely have time for a real holiday anyway.

I don’t think I fall in the latter camp – I have a 12 month job, some of which involves contact teaching while the undergraduates are about, but which also involves a myriad of other things, like for example, today I was attending graduation and a garden party. It’s a hard life. I also hope to get at least one grant submitted in the next couple of weeks and the list of things to do on my whiteboard seems to grow each day – writing a whole new lecture course for September being very high on the list. So, like most people, I work hard, and this is in large part due to the fact that I enjoy my job. But the reality is that it can be hard to find time to take off on holiday. This is compounded by the odd way in which academics often end up to all intents and purposes as their own boss – so if you are mainly having to justify time off to yourself, it can be hard to tell yourself you really deserve it, or can really afford to take it off.

This is interesting as I have just finished reading “Quantum” by Manjit Kumar (which is well worth reading – it gives an excellent overview of the development of quantum mechanics in that golden area before the second world war, but rather rushes later developments that came later). In the book it tells the story of scientists who once upon a time led very different lives to us – no internet, no email, telephony in its infancy – you could wait years to see papers in print. This meant that scientists worked in greater isolation, but nonetheless the cohort of scientists who worked developing quantum mechanics managed to do something perhaps that has never really been done since. And, what kept cropping up was that they took lots of holidays. Bohr, Heisenberg etc were always popping off on walking trips, skiing outings, sailing and even going on academic ‘tours’ which probably involved a fair bit of travelling. Perhaps if you are a bunch of geniuses you can get away with lots of holiday – but I do think it perhaps suggests that sometimes academia takes its self rather seriously. Breaks are needed by everyone, working all the time is simply not good for the majority of us. Holidays perhaps allow a bit of that much needed thinking time. Me? Well, I had planned to take a week away with the family during the school holidays. After reading ‘Quantum’ I’d really love to take three, but have convinced myself that I definitively have to take two full weeks to recharge. Then I can come back and get stuck into the new challenges that will be coming my way in the next year or so. If you are an overworked academic – just ask yourself, ‘what would Bohr do?’. He’d go walking.

Inspiring the kids and vice versa

I was a judge today (14th June) at the Big Bang Fair Scotland at the SECC in Glasgow. I have had the pleasure of taking on this role several times over the past few years and this year the event was the biggest yet. There were an estimated 4000 kids due to attend with hundreds of competitors from schools all over Scotland, even from as far away as Shetland.

One of the big things that the judges are told is that the judging is actually a highlight for the kids, that the discussion with a professional scientist or engineer is a big deal, a form of validation, and it helps to add a little to the inspiration that hopefully they are all privy too as part of being involved with the competition and the event. Equally we are told not to be too hard on them, and to focus on the positive, as this can shatter the experience and put them off science and engineering.

I never have a real problem with the judging – the kids are always fairly enthusiastic and rightly proud of what they have done – the projects are often amazing – 10 year olds building working wave electricity generating machines, teams building little satellite sensor systems in a juice can, volcano investigations, Raspberry Pi controlled racing cars, Robots (lots of robots) and more renewable energy houses than you can shake a stick at – and it’s clear that they have the bug. They have been inspired. And this is in very large part due to a group of very dedicated, hard working and brilliant teachers who are the ones to help pull all the projects together.

What I found this year was that I was inspired to actually try and do something myself – one of the science club projects was sponsored by the Weir Group, and it was to look at using 3D printing to build a water wheel system. This involved giving those schools participating a 3D printer. On speaking to one of the teachers from Eastbank Academy in Glasgow it was also clear that the printer had hugely impressed some of the teachers and that the possibilities were huge – the kids had used it to print all sorts of stuff, from minecraft objects to jewellery. The comment we both made was that soon every school will want one.

3D printer at the Big Bang Fair Scotland

3D printer at the Big Bang Fair Scotland

So that got me thinking – one of the things Universities are supposed to try and do is engage with the local community – so why don’t I (or at least my School/College) try and get one of these devices in every high school in Dundee? I haven’t quite thought through the details yet, but I’d hope the University, some local businesses and maybe some crowdfunding might allow me to get to the target needed. There are other details to consider such as ongoing consumable costs, but let’s not let them spoil my afternoon vision. So my goal (and making this pledge in public might actually focus my mind) is to try and give the local high schools of Dundee a 3D printer as a Christmas present. I see this part of the “Transform Dundee” vision that the University of Dundee has.

If anyone wants to help in this endeavor, let me know. If anyone wants to point out the fatal flaw in my idea, that’d be good to know as well. If anyone wants to pledge money to support it, drop me a line and I’ll work out someway to take that from you.

The Droplet Laser

A laser is a fairly simple thing at heart. You need a couple of mirrors a chunk of material with the appropriate atomic characteristics and an energy source to get it all started. When teaching lasers to my undergraduates I often flippantly remark that “if you hit it hard enough, pretty much anything will lase,” [1] meaning that if you can get enough pump energy in the material requirement of the laser material don’t matter too much. While this isn’t quite true, it didn’t stop some of the original laser pioneers trying to make an ‘edible‘ laser out of jelly (or Jello-o for American viewers). In this they didn’t quite succeed, but they were able to get gelatin doped with fluorescein dye to lase and this could then be eaten, as the dye “was almost non-toxic”.

In some recent work (Optics Letters 38 1669 (2013), behind a paywall, sorry) work between my group and Alper Kiraz‘s at Koc University in Istanbul we have had a shot at making both slightly unusual and potentially edible substances lase, namely a microscopic droplet of water. This too is based on using the water droplet as a host medium for the lasing material (Rhodamine-B – which is likely a carcinogen, so you might not want to digest it) and a bit of glycerol for stability. Our work is based on using optical tweezers to trap the droplet in mid-air using an infra-red laser and then we illuminate it with a second pulsed, high energy, (green) laser. The droplets (water aerosols) are around 10 microns, so 10 millionths of a meter, in diameter. Pretty small! The nice thing about water droplets is that they tend to form very nice spheres, and this gives us a very simple way to form an optical cavity. Normally we would use mirrors to form the cavity, for example in a Helium-Neon laser, but here like that gets into the droplet can undergo total internal reflection and can get trapped inside. This enables a large optical field to build up and gets us above the energy threshold needed to see any laser action. This effect is called a whispering gallery resonance, and is the same effect as seen (or heard) in cathedral domes, like the ‘Whispering Gallery‘ in St. Paul’s Cathedral in London. Here, if you stand on one side of the gallery and whisper into the wall, the sound is able to creep around so that your friend on the opposite side of the dome can hear you clearly.

In the figure below you can see the output from the laser – these are in the form of cavity ‘modes’, which are the little spikes in the diagrams. The top two figures show the outputs below the laser threshold, while the third shows a higher pump energy and laser action. The inset shows the trapped laser droplet.

Droplet Laser Modes

The figure shows the outputs of the cavity formed by the water droplet – the peaks indicate the ‘modes’ of the cavity, where a whole number of wavelengths fit round the droplet circumference. The top two figures show the output below the laser threshold, while the lower figure shows ‘laser modes’.

Our laser is not the first to make use of water droplets as the lasing host – there has been work on bigger droplets trapped using ultrasound and on surfaces but ours is the first to make use of optical tweezers to hold the laser. This should enable us to look at very small droplets, explore tuning of the laser through controlled heating, and it gives us significant control over the movement and placement of the droplets.

So what could you do with a droplet laser? Well there is quite a lot of work on using whispering gallery modes in solid spheres as sensors, and one could imagine extending this to liquid spheres. As we can easily place things within the droplets we could also use them as more general probes – the idea would be that perturbation of the laser in some way would allow us to probe the contents of the droplet. It might also allow us to sensitively probe the shape and dynamics of the droplet, which is very hard to do otherwise due to the very strong surface tension. We are only just starting to think about the possibilities.

On a personal note, this is an experiment that I thought up many years ago, and which we started to do when I worked in St. Andrews. We got some preliminary results showing droplet fluorescence but then the PhD student working on it had to write up and finish and we never quite got back to it. So it’s very satisfying to have finally done it, with a little help from my friends, and also that no-one else has done it in the meantime!

[1] Turns out this was a phrase used by Art Schawlow (see here, well worth a read), which means either great minds think alike, or I pinched it from him. I’ll stick with the former.

Physics and Life Sciences/Biophotonics Initiative

It seems appropriate that as EPSRC starts up its ‘Understanding the Physics of Life‘ network (also discussed by Athene Donald on Occam’s Razor) that we in Dundee are also starting up a new collaborative project between Life Sciences and Physics. The College of Life Sciences in Dundee is a world leading centre of research in a range of biological topics and in many ways is the dominant research centre in Dundee. Physics plays a rather more modest role in the life of the University, but in recent years we have been gathering significant momentum, and a range of pilot projects between physics and life sciences have now started to deliver results.

We have had some grant success recently as well, playing a part in an MRC Optical Microscopy proposal funded through Life Sciences and we have also just been awarded an Innovative Doctoral Programme ITN based at Dundee to help train a number of early career researchers in fully interdisciplinary projects. This should become active next year and lead to a significant boost in the number of projects we run between our two departments.

To try and cement these relationships further we have also established a trial project to host a space within Life Sciences that can be used by physicists to develop new techniques and tools side by side with the biologists. Our initial goals are to look at the development of new light sheet microscopy devices as well as test out in-house developed lasers for suitability as multiphoton imaging sources. We have a one year postdoctoral position advertised at present to work on these topics and also try and act as an interface point for staff looking to try out new pilot projects – including some of my own on intracellular optical manipulation. So if you are looking for a new interdisciplinary biophotonics role or know someone who is, please apply at the link above (you can contact me for more info).

We are also expanding our staff in biophysics – we have just welcomed Dr Ulrich Zachariae to the Division, who will work on computational biophysics problems, and hopefully will form close ties to the Drug Discovery Unit here, and will be welcoming a further biophotonics staff member next month. We have also been very lucky in our recruitment process for ‘Dundee Fellows’ and we’ll be adding another computational biophysicist later in the year, and hopefully to other biophysics areas depending on if offers are accepted.

Our goal in all this is to try and tackle new and bigger scientific problems by working together and we have exciting plans to try and make this area grow further at Dundee. So I am hopeful that we can make a big mark in the ever expanding research world at the physics and life sciences interface.

Printing the Moon

A few weeks ago I had the good fortune to attend a conference (in a loose sense) that was a million miles away from my normal academic meetings – South by Southwest (SxSW). This is a huge multifacted event, with over 100,000 attendees covering interactive. film, music, education and every other form of tech meets new media that you can think of.

I was there because I know a man who knows a woman who happens to work at NASA. My brilliant colleague Jon Rogers, a product designer in our Art School, works on a range of projects exploring how to make data ‘physical’. NASA, who have a desire to make their open data more used by interested parties have been developing a ‘Space Apps‘ challenge to try and focus people, in a crowdsourced manner, around certain topic areas. As one might imagine these challenges and their solutions are fairly software based, but NASA also wanted something a bit more hardware oreintated – hence ‘Making Space Apps Physical’. Jon wanted to try and broaded this idea out and so asked a couple of other designers, Sandra Wilson and Jayne Wallace and myself to get involved, adding to the team that already included Ali Llewellyn from NASA. This led to us submitting a panel proposal for SxSW this year, which was (surprisingly) accepted, based around this idea of making space a bit more immediate, a bit easier to interact with.

And so the “Print the Moon” project was born – my little contribution. The idea arose from an Advanced Higher (final year Scottish high school pupil) who wanted to try and do an experiment on Astronomy. We lent her a telescope and then suggested that she could try and do some measurement on craters on the moon looking at their shadows. Even with a decent telescope like ours this is not so easy, so I thought about how you might be able to do the same thing in the lab. With the ability to 3D print objects it seemed like it should be possible to print out a crater and then just use a torch or other light source to do the experiment, and this was the challenge I sent to a group of our keen undergraduates.

Essentially the problem was to find the right data and then take that and turn it into something readable by the 3D printer (or rapid prototyper). The data was provided by NASA’s Lunar Reconnaisence Orbiter with it’s Lunar Orbiter Laser Altimeter instrument providing 3D surface topography. The students then ported this into Matlab to plot the surface, sent it over to Meshlab for cleaning up and then sent it to Solidworks to output it to the printer. As an educational tool this has proved very valuable, as the students had never really used any of these before (expect Matlab). A copy of the Korolev Crater is shown below, from the dark side of the moon. You can then do a bit of trigonometry to try and get the crater dimensions based on shadow data. So all in all it works quite well.

3D version of Korolev on the dark side of the Moon.

3D version of Korolev on the dark side of the Moon. Spot the deliberate mistake.

And we took this over to South by Southwest and talked about it on the panel, and I even got to meet an astronaut. I’m very proud of my students getting stuck into something like this – a project that has no academic bearing on their courses – done just as it’s a bit of fun and it helps you to learn some new skills. I also think we could maybe push this towards a publication in something like the American Journal of Physics and will hopefully have some Nuffield Bursary students working on this over the summer to try and gather the necessary data.

Our students were also on hand at an event organised by New Media Scotland, the LateLab, as part of the Edinburgh Science Festival to talk about their work. And there is still more to come, with other events still to make use of out little chunk of the moon. Oh, and if you want to get involved, there is a Space Apps Challenge: “Dark Side of the Moon“.

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