Geoverse

Not much is going on other than that i’m freezing my arse off in the house. They say it’ll get even colder so im going to get a heater soon. But nevermind that. Last week I took a break from my research project by attending a 3-day workshop on communicating science. We practised how to hold presentations about your research and how to write a newspaper article in laymans terms. I know I know that there are science journalists who do this for a living, but just imagine that as a scientist you often get asked yourself to explain your research. To one of these journalists for example. How would you fare? Well let me tell you the absolute truth. You’d do miserably! That much have I learned at this workshop. Science is littered with terminology the simple mind has never heard of. You’d describe processes that they cannot relate to in every day life. How do you expect to sell science to the general public if they cannot understand a word you are saying in the first place? So that’s what this workshop focused on. It took me two long nights to finally get my research in words that most people (“a well read 12 year old”) could understand, nevermind that it’s not exactly what my research is dealing with. So below is my latest version of a news article about my research. It’s by far not finished before it would be something that could be entered in a news paper. The other thing at the workshop was giving presentations. That was nerve racking! Even though they had to be short, the amount of attention to detail is immense. How do you stand? What do you do with your hands? Do you look at the audience? Do you engage them? How’s your voice? No uhms, or ah’s? Loud and clear? Not too fast? Do you include pauzes? etc etc. Definitely things to look for when giving a presentation next time be it to a general audience or your science group.
______________________________

The Earth is a hard boiled egg

CANBERRA: Scientists at the Research School of Earth Sciences at ANU
hope to prove that the Earth’s mantle is actually solid. The previous
Earth model represented an unboiled egg with a liquid interior.
However, new evidence points at the Earth to be just like a hard boiled
egg with a shell called the crust, the solid eggwhite is the mantle and
the yellow yolk in the centre represents the core.

We know that sound travels differently through different materials. In
Western movies it is often observed that the cowboy puts his ear to the
ground to hear his approaching enemies on horses long before he can hear
them otherwise. Sound travels faster through rocks (a solid) than
through a liquid. This phenomenon supported the previous Earth model
with slower sound waves in the molten liquid mantle.

However, this may prove to be incorrect using new laboratory studies
where rocks sampled from volcanoes are exposed to high temperatures and
pressures and the speed of sound is measured within them. According to
Mr. Farla, the lead scientist “these rocks are not molten but contain
varying amounts of tiny cracks, smaller than the diameter of a hair or
even smaller than a blood cell. These micro-cracks can theoretically be
responsible for slowing down sound waves.”

To understand how micro-cracks in rocks slow down sound waves imagine a
crack as a long piece of string with foam cups attached on either end.
One person talks into the cup and the other person far away holds the
cup to his ear and listens. When the string is tight and straight it is
possible to hear what is said in the cup as sound travels as vibrations
in the string. But when the string is slack this wont work because the
vibrations die out before they reach the other end.

If this theory proves correct then our understanding of the structure
of the interior of the Earth will be greatly improved. The application
of such knowledge includes mapping, better understanding of continental
drift and discovering geologically active planets and moons, which in
theory would be able to support life just like on earth.

I updated my website with a nifty posting system. Have a look if you got a couple of minutes to spare. A proper blog post will come later. I can’t post much if nothing much has happened 😀

I’ve been pretty busy up to now. Thankfully we have a 4 day easter weekend coming up. I intended to go to Sydney but there is an Easter party on Sunday and on monday I may get a double bed from a graduated and departing PhD student. She has been accepted as a post-doc fellow at Oxford! And I wanted to work some more on my website / make a new one so friday and saturday would be good for that. I still need to do some sightseeing in Canberra anyways as well. My house mates will be off to check up with their folks. But that’s not what this post is about. 🙂

I’ve been doing a lot of SEM work lately and yesterday I had my first session operating the Cambidge SEM apparatus. The samples we are using right now are not mine but they are useful because mine will be similar to them. Oxidation of the iron bearing olivine samples, that have been pre-deformed, allow me to image
dislocation lines (as well as grain boundaries) with BSE (electron
backscatter) using the SEM (scanning electron microscope). Oxidation will
increase the average atomic number at edges, dislocations and grain boundaries
increasing the frequency of backscattered events and consequently these areas
show up with a bright contrast. The advantage of using the SEM over the TEM
(transmission electron microscope) is that lower resolutions can be taken to
increase the scanning area and improve upon more representative unbiased
dislocation density measurements. Also sample preparation is much faster for
the SEM than for the TEM. A 10 -12 minute alumina polish (grain size ~0.05μm)
removed most of the oxidized coating on the sample but did not remove the
oxidized dislocations themselves. BSE imaging was done at 20kV and 500pA.
I’ll be trying lower voltages at 5, 10 and 15kV as well. A lower voltage is
preferred because it will reduce the imaging depth of field (DOF) and decrease
the 3rd dimensional component which causes blurs to be visible of features underneath the surface in the
2-dimensional SEM image. The downside is
that because the sample contains atoms of a higher atomic number (Si, Fe, Mg…),
a too low voltage will not force powerful enough elastic collisions with the
atoms and the backscattered electrons will be in a diminished concentration and
consequently only very low contrast images will be obtained. Low contrast images
may or may not be useful. That’s what I’ll be determining on next Wednesday when I’ll be using the ‘new’ Hitachi 4300 SE/N SEM apparatus rather than the 15 year old Cambridge one. The Hitachi supposedly handles lower acceleration voltages better.

Anyway, there ya go. 🙂 Once I sort out the best method of obtaining SEM images of dislocations in olivine and how to best estimate the dislocation density in the olivine samples I’ll be focusing my attention to torsinal forces oscillation experiments, dislocation annealing and hot pressing.