I apologise for things being a bit quiet around here recently – I can only blame my shonky time planning in failing to fit new posts in. I’ve actually started penning 3 or 4 over the last couple of months, then something has got in the way and by the time I got back to the post it seemed a little old and irrelevant.

The major reason it’s been so quiet is that I’ve been solidly ensconced down in the modelling lab since January making headway on the project work which I aim to have finished by the end of May.  That I’m writing a post now is largely because after a smooth start, some unexpected observations, a detour, and most recently a proper pause while I stopped to try and figure out a problem, I’ve been reflecting on the nature of experimental work, and how we go about navigating these little issues.

I’ve been assured by colleagues that it’s not just me that hits these speedbumps – they are a natural part of experimental work. So I write this post for new researchers who perhaps have not found their first hurdle yet, or perhaps those of you who are just interested in how experimental science jogs along in between those times we’re excited about a new project and publishing the resulting papers. And for those of you who know this all too well, maybe it will at least be a comfort to know that everyone else has the same problems.

Unless of course it is just me who has these moments, in which case I guess you can just all point and laugh 🙂

Snapshot from one of this mornings runs. That big plume of pale material growing through the left side of the image was a bit of a surprise.

Snapshot from one of this mornings runs. That big plume of pale material growing through the left side of the image was a bit of a surprise.

Any experimental research project begins with either a hypothesis, or at least a series of behaviours that you want to investigate. While conceptually this idea might be simple (“see  how fluidised grainflows deposit”) all sorts of interesting phenomena and experimental obstacles can get in your way. For example, after I analysed the first months worth of experiments I realised that the material was behaving strangely when it was in a particlar configuration. It’s an interesting physical phenomenon which had been seen before by a colleague in the lab, but as far as we’re aware not published on. So, at this point, do you try to find a work around for the issue, or do you divert and investigate this new problem? The answer will depend on your funding and your timescales. But consider there’s also the possibility you might not find a workaround. In the words of Tolkien:

“There is nothing like looking, if you want to find something. You certainly usually find something, if you look, but it is not always quite the something you were after.”

Sometimes these things can open new avenues, sometimes you’re presented with something which makes your work more difficult to interpret or less valid for the case you had hoped to compare it to. Sometimes you just hit a dead-end and you realise your line of enquiry is going nowhere.  And sometimes you hit upon something and you can’t necessarily tell which of those many things it is.

So it was that I was stood in the lab this morning resting my head on the handle of a broom, staring into the middle distance trying to work out a chewy problem with regard to how to get the information I wanted under the conditions imposed by the equipment, and considering a number of little hurdles which have been identified in the last 4 months.

The original research project had been to see how flow and deposition occurred in granular flows which have a high gas flux passing through them, and when their material supply lasts longer than the timescale it takes for the front of the flow to come to a halt. These fluidised sustained currents are how we believe the largest ignimbrite-forming pyroclastic flows behave. Particularly vexing for me is the attempt to get a long deposit profile, without getting drawn into a messy problem involving the rate we inject gas at a particular point (which seems to have a weird control on the flow, but we can’t understand why, so we’ve put it to one side to deal with in a future dedicated project).

At the end of the day dealing with these problems is part of the fun of experimental work – finding where the obstacles are and then navigating them is what the research is all about. But sometimes you end up leaning on a broomstick staring into the middle distance on a stinker of a problem you can’t wrap your head around.

When I find myself doing this (and it happens quite a bit more than I think people realise) I have a very simple way of moving forward*. Sit down, grab the lab notebook, draw a line under the last entry and start writing down what I’m trying to do, what the problem is, and write down every idea that comes to me about working around it.  I don’t know why, but for some reason writing it down in this way helps incredibly. Next time you have your chin on a broom handle and are trying to stare-out a wall, give it a go**.

Within a 20 minutes I had settled on an approach to work around the problem that will get the results I need in a meaningful way. Much success!

And so it was that 1 run later I discovered a whole new ‘feature’ of the experiments we had no idea was happening. Back to the broom it is.

I’ll leave you with a quote from Feynman that I love and think sums up the whole thing rather nicely.

“Science is the belief in the ignorance of experts.”

*One successful method at least. The fall back I rely on is to go and find somewhere to have a few beers in the sun and hope the problem goes away. Not yet successful, but a pleasant way to spend a day.

** May work for other postures.

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Accretionary Wedge #55 – Geological injuries

So the Accretionary Wedge comes around again. This time we are given the theme of Geo Injuries, and Maitri starts us off with a series of painful looking contributions.

Geologists are known for spending a lot of time outside, if not smacking rocks with hammers, then climbing over lava or scrambling across wet foreshores. It’s no surprise that injuries occur.  One of my professors as an undergraduate would wax lyrical on field trips about safety glasses and hammering technique, using his glass eye as a rather good example of what can go wrong when people aren’t paying attention to others around them.

I have been very fortunate in that I can’t recall picking up any real injuries while out and about (although you’d be surprised at the scrapes and cuts you can pick up in a lab).  I’ve spent quite a few hours in A&E with undergrads who have injured themselves on trips I’ve been on though, and I have to say the worst (a very nastily broken ankle) was a result of stupid messing about on a bit of flat pavement during a lunch break. I also recall a lecturer spending some weeks in plaster after a late night fall off a sea wall onto the beach below. So it goes to show that the risk is all somewhat relative.

That’s not to say I’m not prepared for an accident of course.  One of the things I most enjoyed back when I returned to academia to start my PhD was doing a ‘fieldwork first aid’ course.  I spent the best part of a decade with St John Ambulance, so considered my first aid skills to be pretty good. Pretty much every other weekend was spent out providing first aid cover to public events, and we saw all sorts. Everything from cuts, grazes and asthma attacks through to people having their horse fall on them after failing a jump. However, the nature of first aid in those cases is basically about making everything safe and getting people to hospital as fast as possible.  Fieldwork first aid presented a very different concept – that of being out in isolated wilderness and trying to vastly increase your mobility and longevity at the expense of injury in order to be able to get help. It was fascinating, but I hope I never have to practice it.

The closest I came to me needing that kind of training was actually about 6 years before, while I was still doing my undergrad. On a trip to Almeria in Spain we had hiked up on top of a hill to look at some carbonates. Very clear instructions were given on the route to get back down to the coach. Inevitably someone managed to either not hear or ignore the instructions, convinced he knew better.  He took the steeper direct route.  It was about 20-30 minutes to get back down to the coach, and there was no sign of Charlie. We looked around, then heard a “Uh – guys…”

The coach was parked next to a 5 m tall cliff. At the top of that, on a narrow ledge, was Charlie. He had managed to get himself down the 2 m cliff behind him, but was now stuck, as he couldn’t get back up. Below him was a 5 m drop, surrounded by cactus.  To say we laughed at him doesn’t quite express the level of pointing and namecalling that happened, and to this day I have no idea quite how he and Shane (who volunteered to stand underneath and catch him) got away as injury free as they did. I have a photo somewhere of the panicked look on his face as he tried to lower himself to Shanes waiting arms, but a) it’s still analogue and b) it’s in the wrong country.

I digress.  I should also be more honest.  While I’ve never experienced physical injury in the field, I should admit to an emotional one.  A pride-stinging moment which one or two of my colleagues still like to remind me of every now and again. Something of a running joke shall we say.

3 years into my PhD we had a new postgrad student start on a big tephra-related project the department was involved in.  He was coming from a geography background, and while he’d worked with tephra in the lab, was not familiar with stuff in the field. As it happened I was scheduled to go out to Tenerife alongside one of our undergrad field trips in the September – I was going to spend a couple of days helping out with the undergrads, and the rest of the week trying to look for shear instability features in ignimbrites along the southern flank of the Canadas system.  So the new student, whom we shall call Paul, for that is his name, was booked on the flights to come and join us. He was going to be my field companion, or, as I increasingly thought of him during the week – a convenient walking photography scale. In return for his 180 cm of vertical standard, he got a crash course in identifying pyroclastic flow and fall units, and the features of each.

And so it was that we found ourselves several days in doing driveby geology on the narrow roads near El Rio. We needed contacts between flow units, and we had got good at spotting them. The road cuttings provided some great exposure – cliffs of vertical clean section. A geologists dream. It was then I saw a beauty off in the distance – perhaps three quarters of a kilometer away. A pale wall, probably 10 m tall. A clear band separating the two graded units. Flows almost certainly. I checked the satnav to see what the best way of getting close to it was so we could go and have a good look. I pointed at it and explained to Paul what we were looking at. He wrinkled his nose up at me. “It’s a wall” he said with that voice that suggests we’ve been looking at nothing but the same damn walls of rock for the last 3 days and it’s about time for a beer.

At this point I should have just accepted that his youthful but inexperienced eyes were at least youthful. Blasé confidence got the better of me as we rounded a corner and the section went out of sight for a while.

“No”, say I. “Definitely flow. You could see the grading.

“It was a wall. Looked like the inside of an old water tank. It was green“.

My nemesis

My nemesis

Well, after a bit more to-ing and fro-ing we turned another corner, and what was very clearly the one remaining wall of an old concrete-lined water tank hoved into view. For the following days there was no let-up as the inevitable references to water tanks came up at each exposure. It became his favourite anecdote for about a month and a half.

The scars are on the inside.

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Meteor madness 2 – look at the size of that thing

So yesterday was all abuzz with cool videos of the Chelyabinsk meteor, and a whole bunch of questions.  How big was it? Did any of it hit the ground? Did it explode or not? How fast was it going?

Today we start to get some refinement on the preliminary answers.  Most startling of all of these are the size estimates.  The original numbers given by the Russian Academy of Sciences were that it was about 2 cubic meters, and 10 tons.  That was handily blown out of the water by estimates made from infrasound stations, which put the numbers at 15 m  diameter (~1700 cubic meters) and 7000 tons.

This morning that number has been further increased to 17 m diameter and 10,000 tons.  This thing was approaching the atmosphere at 18 km per second, and is estimated to have released 500 kt TNT equivalent of energy during the event, over a period of 32.5 seconds. To put that energy in context, the “Little Boy” bomb dropped on Hiroshima at the closing of World War 2 had a yield of approximately 16 kt. So, assuming it was shedding energy at a constant rate (which it wasn’t) it is almost exactly the equivalent of a Little Boy detonation for every second it was in the atmosphere. For a while this thing was glowing brighter than the sun.

Witness photo of 2013 Russian meteor event made ​​from Chelyabimsk Drama Theatre, Nikita Plekhanov

Witness photo of 2013 Russian meteor event made ​​from Chelyabimsk Drama Theatre, Nikita Plekhanov

So, It entered the atmosphere, created an airburst at between 30-50 km altitude, and is known to have hit land in at least three places – two near Chebarkul lake (an impressive picture of the hole left by one of them is available here), and another 80 km away near the town of Zlatoust. There’s reports of another couple of pieces that may have come down in Khazakstan as well.

Looking forward to seeing what comes of any samples they recover, which will tell us what kind of meteorite it is, and will probably lead to some recalculation of the numbers given so far.

In the mean time DA14 passed – as expected – without incident.

I’ll leave you with a pretty incredible animation that puts the spotting of these smaller asteroids in some perspective.  This demonstrates the history of asteroid spotting over the last 30 years far better than any plain description can.  What else is out there?

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Meteorite madness


[Updated 11.00 am CET]

[Update 2 13:40 CET – impact crater located and reported at 6m diameter]

[Update 3 20.00 CET – massive revision on the meteorite size. Early estimates of 2 cubic meters and 10 tons, increased by 3 orders of magnitude to 700 tons and over 3000 cubic meters (15 m) wide]


[UPDATE 4 – 16th Feb. Size revised upward again – see here for more info]

I was looking forward to seeing what exciting meteorite news today would bring. Far from precognition, I was anticipating the rather close flyby of asteroid DA14, which in a little under 12 hours is due to pass about 34,000 km over our heads.  While the ISS orbits at a piddly 300-400 kilometers, 34,000 km puts DA14 inside the orbit of our geosynchronous satellites.

Little did I realise that I was going to wake up to the altogether more spectacular footage emerging from Russia this morning. At about 9.00 am local time an asteroid plunged into the atmosphere over the Chelyabinsk region of Russia.  This was particularly good for several reasons. Firstly, it’s a time in the morning when there’s plenty of people around to see it, secondly, it was a beautiful crisp clear winters morning, and thirdly because it was in Russia, and the Russians love to have cameras on their car dashboards. Who knew corruption and scamming could have scientific benefits?

The result is videos like this:

and this

To have any footage at all of these events is unusual and useful. To have so much footage from so many different angles and perspectives is really quite incredible. There’s a good repository of some of the best clips here from Emily Lakdawalla


The obvious question which starts cropping up is whether this meteor is related to the DA14 event.  That question I think has been adequately dealt with – at elast based on preliminary data – by Phil Plait (@BadAstronomer) who summarises that

“I do not think this is related in any way to the asteroid 2102 DA14! For one thing, this occurred about 16 hours before DA14 passes. At 8 kilometers per second that’s nearly half a million kilometers away from DA14. That puts it on a totally different orbit.”

and furthermore

“from the lighting, time of day, and videos showing the rising Sun, it looks like this was moving mostly east-to-west. I may be off, but that’s how it looks. DA14 is approaching Earth from the south, so any fragment of that rock would also appear to move south-to-north.”

I strongly recommend you read his post in full, as it also encompasses some great images.

The information coming out of Russia has been somewhat confused.  Initial claims even suggested the military had shot the meteorite down – a somewhat outlandish claim.  Injury estimates were ranging anything between 0 – 100, although the Russian Interior Ministery has since updated the numbers to over 400 people seeking medical attention. These were mostly due to broken glass, caused by the enormous sonic boom as the meteor passed overhead.

UPDATE: Meteosat caught the moment the asteroid started entering the atmosphere

There’s a massive thread on r/AskScience at Reddit that I’ve been looking after for the last few hours that’s worth checking out.

Here’s some more link and video repositories you might like to have a browse through.



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When Twitter goes bad…

Very very short post for no other reason than this amused me and I thought some others might like it. Every few days Twitter sends an update suggesting people to follow based on who you already follow. So if you follow, say, BBC News, they might suggest you follow the Associated Press.

Among many other things, I follow the very amusing Drunk Hulk. This is the recommendation email I just received:

Hulk deGrasse Tyson


I can only assume he has some off days?

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The experimentalist

I got asked a question the other day, and it got me thinking. The question was ‘what makes a good scientist?’

The more I thought about it, the more I realised that while there are a number of key traits that I considered central (‘lateral thinking’, ‘good communication skills’, ‘self motivated’), I could think of well regarded professional researchers who were exceptions to each of them. The only skill I have been able to settle on so far as being universal is the ability to critically think.

There are scientists who are team players, and those who are better working alone (for their own, but often also their colleagues sanity). There are plenty of careful scientists with a precise and measured approach to everything. There are also many I’ve come across who are often a little more slap-dash and clumsy, but who churn out excellent science nonetheless.

I also don’t think research scientists are more intelligent than the general population. We’ve been trained to look at problems and think in a certain way, and we draw on a lot of experience and education, but given those factors I think most people could do what we do.  There’s nothing in our skillset and abilities that can’t be taught.

It was then I realised what the other common factor is to every professional science researcher I know. A love of the science.

Pay and conditions for researchers aren’t that great. While you’re still in school, the people who started work at 16 will have 10 years of earning and promotion behind them, while you’ve been racking up debt. The PhD process is well known as a tough slog, and you then begin hearing rumours that there are far more PhDs being produced than there are available jobs. If you get lucky you then start a career at a moderate level of renumeration, but requiring years in short term contracts which often mean migrating nationally or internationally.

Despite all that, most postdocs I know love their jobs. Sure, they get pissed off at the moving and instability and the general climate of work, but they still love their jobs because they love doing the science.

There are plenty of people who get their PhDs and have the love of science beaten out of them by the time they finish. Or at least that love is overwhelmed by other needs or desires. And there seems to be a reasonable amount of work available for those people. In fact, these other jobs also tend to get paid a hell of a lot more than those in research. Which again highlights that those who stay in it are generally there for the love of carrying out cutting edge science.

In my quest to give a more comprehensive answer to the question I’d been posed I decided to try and concentrate more specifically on my own type of work – that of experimental science.

Here it is more specifically important to maintain a methodical approach. But I find an almost playful inquisitiveness is also really important.  Just this afternoon I was having a conversation with a colleague about the benefits of spending some time just messing around with the equipment and materials you have available to see what interesting behaviours and features can be encountered. In fact, an interesting point came up when my colleague explained that next week he is going to be letting some Masters students loose on trying to model debris flows. He made the excellent point that quite often what they do is crazy and illogical, as they do not have the base of experience to know what *should* happen. But we also agreed this can be a fantastic boon, as they have none of the preconceived notions of how a particular method should be carried out. So while there can be a lot of ‘failed’ experiments, and they learn a lot of lessons about why certain things are done certain ways, both of us fully intend to go and see what they attempt and see if we can’t learn a few things ourselves about what features and flow processes might be investigated with a little bit of a leftfield and original method.

So what traits are essential to your field?

I’ll leave you with a video I put together today showing what happens when you pass gas through a powder material at such a high rate that the material passes through ‘fluidised’ and comes out the other side as bubbling. Stress chains within the material allow conduits to form. I’ve seen it described in many papers, but it’s the first time I’ve played with the mechanism myself, and took the opportunity to use the high speed camera to record it. I think it’s pretty neat – you can see the discrete gas bubbles pass up the sidewall. It was shot at 1000 fps and plays back at about 1/15 speed (30 seconds of video is 2 seconds of footage – timestamp is in the top right). There’s a 2cm grid on the right for scale. For some reason I can’t link to the HD version, so make sure you select the HD option on playback.

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Measure twice, cut once.

My dad was a design and technology teacher. I was exposed to the arts of woodwork, construction, design and so on as a child, and – while my brother went off and became an engineer – I have to say I’ve not particularly made use of those skills since I was doing my GCSEs. That said, I always enjoyed technical drawing, the precision and 3D spatial planning (and indeed, that same 3D spatial awareness that is so important in many aspects of geology).

While I was doing my PhD and had to design some flume equipment I had a flash of interaction with things again, but it was an absurdly simple three-part flume that a 7 year old could have designed and assembled.  For this current project, however, somewhat more time and effort has had to go into flume design. In fact, the full first month was spent doing little but designing and refining the flume, to ensure it was capable of producing the results I want to achieve without being blown apart by high pressure gases or collapsing under its own weight.

So I found myself with a ruler and protractor drafting out isometric sketches and trying to make sure everything fitted together. Then a stroke of genius hit and I booted up Google Sketchup. I’d used it a few times before, but I reasoned that while I could sketch by hand as much as I wanted, by producing a 3D model I would ensure that all the separate parts would fit nicely, and I could read the numbers for part ordering straight out of the model.

Sketchup models of some flume parts.

And I was right – in fact, it was even quicker than drafting by hand. A couple of people in the lab were quite impressed by these models I was producing and got interested.  I took images of the models down to our outstanding workshop engineer, and he was very pleased with the detail – illustrations of where cutouts needed to be made, clear ideas of where we would need PVC, where we would need aluminium, where perspex, and even where particular joins should be made (and how).  It enabled me to design the somewhat complicated hopper shape (do a Google search for ‘hopper geometry’ and you’ll quickly realise that simply whacking a great big box on top of a release mechanism is not the done thing), and was even able to ensure it would be of a certain volume and mass.

So I was ever so pleased with myself when the purchase order went off with all the outputted measurements for the 75 or so separately cut pieces of material, in a variety of materials and thicknesses.

I was less pleased this morning after an hour in the workshops ensuring that all the pieces fitted together nicely to discover that the 3000 mm x 100 mm x 10 mm  perspex flume base had been delivered at 3000 mm x 130 mm x 10 mm. Sounds trivial, but Perspex is really horrible to cut, even in a well equipped workshop. A 3 m length of it is unwieldy and impossible to deal with without some very specialist equipment.

I checked the purchase order. 3000 x 130 x 10. Bugger. How did they make that mistake. Why did I not notice it? I spent some time cursing myself for not checking the purchase order more carefully. I went and double checked again. Then I went and looked at the original paperwork. The spreadsheet I had specced everything on was correct. Then I checked the order email. I’d sent.  Hmm. That was wrong.

So, what had gone wrong? Idiot cut and pasting. I had copied the details from one part, and pasted them, then pasted the same values for the next part on the list.

In summary, after a morning of ferrying a 3m length of perspex to and fro between the suppliers and their enormous cutting machine to remove 30 mm of excess plastic, I propose a 21st century modification to the age-old adage ‘Measure twice, cut once’:

“Measure twice, cut once, paste once, check”.

At least it was cut too big rather than too small – that would have been both annoying and expensive.

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