chasing mirages

My life lately has been alternating between making progress on my thesis, or and enjoying a more active social life than had been normal just a few months ago. I have a partner who recently completed his degree and, as a result, has come out of his self-imposed near-exile state that he maintained while he was still studying. From a life which involved uni work, computer games, and a reflexive “no” to any suggestions of social outings he is now suggesting social outings on a regular basis, and playing far, far fewer computer games than had been his norm. Now I’m the one who winds up staying home to work on my thesis while he goes out and spends time with our friends. Some days this is very effective and I accomplish enough to be happy I did. Other days I wish I had gone, and don’t manage to accomplish as much as I would have liked, and still other days I go along, enjoy myself, and accept that I’ve just added that much more time to the target completion date.
Ah, the target completion-date. Pretty much everyone I know asks me “when will you be finished?” How I wish I knew! Some days it feels like I’m chasing a mirage—I think about what has to be done to complete a chapter or a section; list them out A, B, and C tasks yet to be done and I can move on to the next part. But then, once I’ve done task A I discover that I also need to do D before that section will be complete, and once I’ve done B I find that E and F need to be added to the list. It is only when I stop and look at what has been done I feel like I’ve made any progress—the pile behind me is growing, but so is the pile yet to be done.
In some ways I’m not concerned and feel like I’ve plenty of time available. I’ve received a sufficient number of “sorry, we aren’t hiring after all due to budget cuts” and “sorry, we had so many truly qualified applicants that it was difficult to make a decision, but we’ve hired someone else” letters that I am pretty certain that I don’t need to stress about finishing on time to have the degree complete so that I can start a job in a teaching position in the northern hemisphere fall semester this year—sure there are a few universities which haven’t yet gotten back to me, but since they haven’t asked for a phone interview yet, I’m not holding my breath on them. This gives me extra time to complete my degree and get papers written for publication before next year’s round of academic hiring, with no stress about being “on time” and that is a good thing.
However, there are still post-doc positions, which seem to be advertised at random intervals. I just saw one today for a position in Europe which sounds like it could be fun. Alas, they want someone by 1 June—if I apply for this one, it would be back to the “hurry up—how fast can you finish?” approach. Ah the joys of a scholar’s life—shall I take my time and work in a low-stress environment and miss out on potential opportunities in the short term, or hurry up so that I can chase every interesting opportunity which comes along and hope that the haste doesn’t cause me to do a poor job?

Because I like it

Thanks to modern social networking web pages I have recently gotten back into contact with old friends from high school with whom I’d lost touch due to frequent moves in a pre-internet era. During our obligatory “what have you been up to for the past couple of decades” exchange of notes I’d described myself as “enjoying life as a PhD student”. This caused one of them to enquire if I had been under the influence when I wrote that, because by the time she’d reached the final write-up for her PhD she was so sick of the project that she was considering something more pleasant, like tearing out her eyes. This exchange brought to mind the advice I’ve heard often for people considering doing a PhD “pick something you love, because you are going to hate it by the end of the project”.

Why? What is it about our system of “higher education” which makes people think that we should hate it? I’ve met some people whose approach to life is to choose to do only things they enjoy; others of us choose to enjoy whatever we do. To my mind, there is no better thing I could be doing with my life than learning and/or sharing knowledge. Why am I enjoying life as a PhD student? In part because my schedule is my own—there is no employer standing over my shoulder saying “you must be at work between the hours of 9 and 5”. If I happen to feel like working at midnight, I do. If I happen to feel like working at 07:00, I do. I am free to set my own schedule, and to make it as random, or as consistent as inspiration makes it. This is a wonderful feeling. I may have a lot to do, but I am the one to decide when to do it.

I am also very much enjoying the project itself. My rocks, particularly as seen through the microscope in thin section, are pretty. They are pretty because of the changes to the mineralogy as a result of their metamorphism. My project seeks to understand those changes by using the chemical composition of the minerals to determine the pressure and temperature at which they must have formed, and then to use that pressure and temperature to tell a story—what happened to that mud to bring about its current beauty?

To do this I get to play with spreadsheets and graphs. I get to run computer models which take input and convert it to data from which I can make more spreadsheets and graphs. And you know what? I like playing with spreadsheets and graphs! It is actually fun to compare sets of data in a graphical format and see how they are the same, or how they are different, and to seek out patterns. I enjoy this so much that one of my biggest distractions from my project is keeping track of my personal data. To help keep me on track with the uni work I track how many hours a day I spend on various activities, so when I’m not playing with my uni data making graphs and looking for answers to questions, I often play with personal data, making graphs and looking for answers to questions. How many hours a week do I spend exercising? Doing e-mail/blogs/social networking? Can I make the graph change in the direction I want it to by changing my activities?

Enjoying the processes and day-to-day tasks required of my project helps keep me enthused. However, as I explained to my friend, one of the biggest reasons I’m still enjoying my PhD project is that there simply hasn’t been enough time elapsed for me to be sick of it yet. Because my goal when I first enrolled in University all those years ago was “to be a student forever” an entire decade elapsed while I was an undergraduate taking classes full-time in anything and everything which sounded interesting. When I did my Master’s degree four years slipped by between enrolling in the first class and handing in the thesis. But here in Australia the university system seems to think that a PhD is a short term project. They give students 3 years in which to complete their projects (note: no classes are taken—this is three years of pure research), and if you can show good progress (and demonstrate that any delays are due to circumstances beyond your control) it is possible to apply for an extension for an additional six months. After that your funding is cut off and you are on your own. So, here I am in that final, extra, six months of my project, not sick of it yet, still enjoying the work, and content to be working away. Speaking of which, time to get back to it…

I spend my days making graphs

There are a variety of techniques used to determine the temperature and pressure at which a group of metamorphic minerals grew. All of them have been built up over the decades by dedicated scientists who combine information from the study of thermodynamics and various experiments wherein real minerals have been made to grow in laboratory conditions. The one I have been using involves a suite of computer programs, which, if given the composition of the rock sample, will plot a diagram showing all of the possible combinations of minerals which grow from those ingredients at any given temperature and pressure. If all of the minerals present have uniform compositions, then it is a simple matter of comparing the list of minerals that are present with the list of minerals which should be present and thereby get a good guess as to the temperature and pressure at which they grew (how good will depend on if the "field" for that particular set of minerals is a large or small one).

However, if there are minerals which are "zoned" (their composition changes from the center to the rim), it complicates things. You see, for this technique to work, all of the minerals have to be in “equilibrium”, which means that the chemical reactions which make them have to have “gone to completion”. An entire zoned mineral, by definition, can’t all be in equilibrium with everything else present, but it is possible for the outermost bit of it to be in equilibrium with everything else present, and the inner portion to be “frozen” and no longer participating in the chemical reactions which are taking place outside of it. When this happens, the “bulk composition” of the wherein the chemical reactions are happening is constantly changing as some of the ingredients get “frozen” in the center of the zoned crystal. In such a case if you know the composition of the entire rock sample these diagrams only tell you what minerals could have been present way back when that zoned mineral first started growing, which list may or may not bear any relationship to the ones which are present now.

So, how can you read the diagram when there are zoned minerals present? You can’t tell what minerals were there at the time your zoned mineral first started growing, because as that mineral grew it subtracted some of ingredients from the surrounding rock, and “froze” them into its “core”. This process caused the remaining list of ingredients present to be sufficiently changed that the list of possible minerals present at any given temperature and pressure also changes. This is not unlike comparing the list of what you might be able to make for dinner on any given evening without going grocery shopping. They day you first stock the house up with food the list of meals you might make from the ingredients on hand will be much larger than it will be a week or two later (if you don’t go food shopping in between) and have been using up some of your ingredients in the meanwhile.

So the “trick” I use is to consider my zoned mineral (in this case, garnet) as being made up of proportions of four specific ingredients. Just as different cake recipes might call for differing amounts of flour, butter, eggs, and sugar, and still be a cake, so a garnet will have differing amounts of iron (Fe), magnesium (Mg), calcium (Ca), and manganese (Mn). (These elements, being of similar size, all manage to fit into the same slot in the crystal structure.) How much of each is incorporated into the growing garnet at any given time will depend both upon the ingredients available and the temperature and pressure at which the garnet is growing. Therefore if we make a diagram which shows the expected changes in quantity of each of those four ingredients in garnet (at different temperatures and pressures) it is possible to find the spot on the diagram which corresponds to the garnet being studied.

I do this by measuring the composition of my garnet using an electron microprobe and making a note of how much of each of those four ingredients (Fe, Mg, Ca, and Mn) is present in the center of the garnet. I then highlight the lines in the graph corresponding to each of those numbers, and where the four lines intersect marks the temperature and pressure of the first growth of garnet. Often this works, and there is much rejoicing. Sometimes it doesn’t.

There can be any number of reasons why it doesn’t work—perhaps I’ve not actually measured the center of the garnets. Perhaps the composition I started with for the whole rock doesn’t actually match the composition that was present when the garnet started growing. Perhaps the composition of the rock has changed with time as fluids carried in new ingredients and carried away old ones.

Creating these diagrams, they joys of having them work, and the frustrations when they don’t are a normal part of my life as a graduate student. Biologists get to play with plants or animals, chemists get to work in a laboratory, I spend my days entering lists of numbers into a file, setting the program calculating based upon those numbers, and, when it is done (it can take quite a while—these calculations are actually quite complex, which is why we delegate them to a computer), opening images in a drawing program to see the results in a graphical format. Once I’ve got results the fun part begins—where I think about what the numbers mean, and how my rocks could have been buried deeply enough to grow these minerals in the first place, and how they managed to get back up to the surface so that I could collect them in the second.