Deep Stuff (by sarah)

Last Wednesday I went to the first of the departmental research seminars it was by Lars Strixrude and was on an area I basically knew nothing about. It was called Minerals to Mantles: The Planetary Mosaic.

There was alot of stuff in this I didn't understand but it did manage to answer some of the more pressing questions I had come out of the Solar Physics lecture with - namely about what was actually being detected/repressented with all the Tomography stuff and so it was I feel a good job I went.

As far as I could tell he was extrapolating say mineral physics to the mantle as a whole and using a similar principle to those you use in transmitted light microscopy in that the direction of the mineral and type affects the way the waves are propogated. This means you would be able to tell alot about say the actual structure of the mantle and the internal workings of the earth - I sort of felt a vagueness that eutectic and peritectic stuff should make an appearance but as I can't really remember what that was all about the reality is probably very far away from my comprehension :/

I felt intreged by the topic and thought I understood what was going on at the time but now I come to write it up its all gone 🙁

But it really reminded me of second year ingneos petrology (at least I think thats what he was teaching) with Stephan Matthai - sometimes I wish my brain worked properlly :/

I had the vague feeling that this fitted into my general thing of wanting to treat things as systems rather than confined subjects but am not really sure - hmmm - not the best blog ever and probably completely round my neck :/

Fun in computer games (by alaric)

I've noticed a pattern in computer games which I find fun. Not all games I find fun; they can be fun in different ways. I'm just saying I've noticed a particular element which subtly contributes towards the funness.

Namely, having to make a tradeoff between two or more competing requirements.

Let's have an example - Desktop Tower Defence. It's a tower defence game, which means that you use your resources to build a set of defences that waves of attackers then flow into.

Firstly, clever placement of defences has a much greater effect than simply how much you spend on them. So the game requires some measure of thought, rather than repetitive accumulation of resources followed by spending them.

But the crux of the matter is that there are different kinds of attackers, which have different weaknesses. A defence set up in the way that would be the strongest against land-based attackers - a long winding zig-zag with turrets along it - would be weak against flying attackers, since they just fly over your layout in a straight line rather than being constrained to the paths. Against them, you want a solid block of turrets in a cross, under the two orthogonal lines they fly along. So you need to establish some tradeoff between the two challenges. Not to mention that there are turrets which only attack air targets, but have a high damage per cost ratio, and turrets which only attack ground targets, and turrets that attack both but have a worse damage per cost ratio. And turrets with long ranges, or high fire rates, or that do a lot of damage per shot, or damage neighbouring targets due to a splash effect, and so on.

Sometimes you can have a tradeoff that's too simple - it's amenable to mathematical analysis to find an optimal result. That's no good. It has to be too complex to work out on paper, but not too complex to grasp. The middle ground between the two is the area where experimentation is rewarding.

I probably ought to read A Theory of Fun for Game Design...

Beatrix Potter (by sarah)

Saturday night we got out Miss Potter a film about who the Beatrix Potter books got published and about her life. This was actually really interesting - especially for me as I feel that some of the children's stories I have written are the modern day equivolent of Peter Rabbit and the rest. Well my characters are called Ester Rabbit and Christina Cluckelsworth and so on. But mine live in the now as did her creations - the characters need to be contempory and in contempory language.

Anyway I digress - Jean has the entire works and we tend to read them alot - we are also near Gloucester which obviously makes a big thing out of the Tailor of Gloucesterwith Beatrix Potter mice everywhere etc...

What I had not realised was that she had taken an active role in trying to preserve the country side and mantain the farms - I feel she was a very far sighted women in many respects - I now a an itch to know more especially as Sunday we went to the World of Beatrix Potter - Jean is still running around with her rabbit ears on she liked the place so much!

Unfortunatly she did throw up on route so Lynne kindly bought her some cloths to wear - this included a Peter Rabbit T-shirt which we have had to crow bar Jean out off for a wash! The exhibition was good but I dont think I'd have gone if I hadnt of had a three year old 🙂

Al did notice a few quiet big disgrepencies between the infor at the exhibition and the film - we have not yet investigated to find out which one is correct. I was intreged to find that Beatrix Potter had really wanted to be of a science/art bent and had applied to do botanical art - I think if I'd been born into her society with the same sort of family rank I'd have been very similar to be honest.

The funniest thing I managed was to announce that I thought the film Beatrix was like Bridget Jones - to which I got a chorus of 'well it is the same actress' - I have not seen the Bridget Jones films I was just running from an extract I had read (but I probably saw trailers somewhere along the line so can not claim complete innocence) - sigh - this always happens to me :/

I took alot of pictures of this so hopefully they will becoming soon 🙂

I like Tunnels (by sarah)

After visiting the extremely cute alpacas we headed off to the Honister Slate Mine on route Simon - Al's step brother asked me what the landscape was. I confessed I didn't actually know anything about the region but I looked at the scenes passing my window and guessed at volcanic with glacial action afterwards.

My back was in a bit of a state still and I bascially could not rotated my head but I really wanted to go in - I am from the Royal School of Mines, I am from Welsh minning stock how could I not go in? This question arose when buying the tickets as Lionel has injured his foot and was using his crutch and had sandles on.

A discuession with the lady on the desk about exactly what the mine was like had Lionel not going but me more determined to go. Jean unfortunatly was wearing sandles so would have to be carried for sections of it but would be ok as long as she was ok with the dark - we were more concerned that we wouldn't be able to keep the hard hat on her!

I have been known to go into mines on crutches - I really can not resist them!

We had to wait for our guide for a while so looked around the shop - I was I have to say impressed. They had been really ingenious with the products they where making from the mined stone - not all of it slate. I thought it all looked a bit odd though and there was definatly some interesting stuff going on in the rocks. It didn't quiet look right as slate to me and there was some interesting flow and flame structures in some of the non-slate. It is lovely stone and if I ever have enough money to do things properlly in the house I shall be getting the stone from that mine.

There is a lovely bluey/green quality to a lot of it.

The dude arrived and gave us our hard hats and battery packs which reminded me so poniantly of going caving I almost backed out but then realise what the problem was.

Jeany initial struggled over the hat until she saw that we were all wearing them - she didn't have a heavey battery pack as she had basically an LED head torch. To my suprise she noticed this - 'I have blue light, special light, you have yellow!'

We clambered into an orange landrover thing and trundled up to the mine.

Outside the entrance we stared at the landscape and low! It had once been a sea flow with volcanics going on on it and then been uplifted etc... and then had glacia's move through it all carving the characteristic u-shaped vallies - these give you a nice cross section through the formation - so in staring across the valley we basically had a mirror image of what we were standing on - this was cool and gave us a much better over veiw than was could have hoped to gain any other way.

I was just a bit chuffed that my guess had been right.

We could see the layering of the ancient lava flows and slate - the slate higher up was the greener colour. Slate normally occurs from say eustry mud which becomes mudstone - this is then folded due to tectonic action and the pressure causes changes so that you get an alinement of say mica along the fold axis - this is the cleavage and is what the slate is split down. This slate looked so odd to me becuase it was not made from mud - instead it was origonally volcanic ash!

This also means that it has more griss - this is the amount of sort of large fragments in it that stop it having a smooth break down the cleavage - therefore this slate breaks into thicker slabs compared to other slates ie welsh or scottish slates. But it also means it is stronger!

The guide dude was called Fred and he was the father-in-law of the guy who set the business up - again I was really impressed as the guy had bought the mine and re-opened it when he had initially known nothing about mining - his grandfather had asked why was the mine closed and he'd just seen the potential and gone with it!

They even went and got a special rock saw from the Itialian marble quarries - this looks like lots of lumpy beads, or sort of an articulated spine of some sort - it is beds of steel or something embadded with industrial diamonds that as Jean point out glittered.

They now mine safely off course but when the mine was origonally open (from the 1700's I think he said but am not sure) they used dangerous tequniques which have resulted in what are known as rate traps - these are rooms where so much of the slate has been removed that the overlaying rock is in danger off coming down on top of the minners if they continue - this was actaully an inefficient way to do it and they get far more out and intact than they used too. Also the range of products they offer now will hopefully buffer them from economic crisis - these are what always closes slate mines as builders stop buying the slates.

One of these rat trap chambers turns out to have great acoustics and a jazz dude has been in there recording this has given me an idea - ok Clare, Ella and Charlee what about us doing something similar - I'm thinking medeaval chants with some electric guitar thrown in would be cool - Becca could even play some flute and Carina how's your guitar playing - infact Becca you play too don't you?

I think we could call ourselves the Mining Babes?

What do you think?

Anyway cough we had a look at the history and stuff and after me rabbiting on about why I thought the cieling of the place worked so well our guide thought that we were musicians but Al and Simon blew my cover and asked me questions about the geology of the place - I was highly embarassed but then it turned out Fred was a Steel Engineer and on top of that I found out that there may be something there that will help me with my MRes project. So I may be going back there sooner than later.

I really love this and Jeany announced that she likes tunnels 🙂 Talking of which there where a few really cool tunnels there that had been in the old days, shored up with the waste stone - this is done with no key stone and is similar to the ancienct burial mounds in Scotland and places. Jean told me off for touching the walls and braeking them which I thought was sweet 🙂 Somehow she ended up getting buscuits out of the other people on the tour :/ How does she do it?

Again photos coming soon hopefully 🙂

Sun Quakes and Solar Structure (by sarah)

I had another really engaging lecture tonight - one that had me salivating for more and which has probably resulted in me alienating myself from the rest of the MRes group.

The lecture was by Vincent Tong who it turns out has been at Imperial where I studied as an Undergraduate!

First off we had to think about what our goal was, what were we actually trying to acheive - to see inside the Earth of other body and see of what and how it is made. Then with lots of analogies which steadily become more rediculous as the lecture went on.

We then decided we couldn't break the Earth (or Sun) open like an egg to see its internal structure but had to view it as a presant and shake it to see whats inside. The shaking equals eathquakes and these we record and measure. We had a quick run through of wave types which was cool as I found I had forgotten one of them!

I ended up having to answer why s-waves which can't travel through liquid are improtant along with many other things - I don't know if they others were just being shy. I found I had remembered alot of stuff and to my suprise I am finding it far easier to infer things from information I am given. I did find the periods of time when we were working with each other to work stuff out frustrating as everyone else just kept saying they didn't understand (bar the guy at the front who kept asking really really techniqual questions about the software used).

We ran through the standard this is how you look at the inner earth but then looked at the fact that the velocity of the earthquake waves are dependent on direction and temperature and their interactions with faults and other subsurface structures. This was interesting as I discovered you can basically use the arrival times of the waves to work out the velcocity of the waves which is temperature dependent - meaning that you can tell if it has had to pass through realitively hot or cold areas. If you then have sequences of these you can see how they change - meaning you've added time and can see how things are moving or flowing - this is so useful I can not even begin to tell you.

The implications to my mind are stagering and I thought seismics where boring!

We ran through (quickly) how imaging of sections works - these are generally done by man made seismic waves (big thumbing lorries or air guns at sea). Now most of the siesmic sections I looked at during my undergraduate (if not all) were of reflected waves that were bouncing off of say bedding plans and the such like. But now there is this thing called Tomography which (I think) involves refracted waves - so these are waves that travel through the rock and are slowed down by different substances etc... sort of a minni version of how we use earthquake waves. I think it is a method stolen from medical imaging but I am not sure.

This again opens a whole new world and means you can see things that are not picked up by the reflective waves. There was somehting involwing time and depths and seeing flow rates again with this but I need to look that up some more.

We also looked at the restrictions off all of this - basically we could really do with a global network of siesmometers and though we are getting there - most of the planet is covered in water - I suggested that they could put the detectors along the cable trunks that carry say the internet - this apparently has already been done. Plus they have detectors that onces having detected an earthquake bobb back to the surface adn tell the sattalites what they heard - I personally wondered what sort of fail rate they have for such instramentation.

I guessed correctly that time would be involved and the problems of refernce and angle etc... which I was impressed with myself for. Also another problem is that the earthquakes on the earth are not actually evenly spread out - they are concentrated along the plate boundaries and the such like giving certain biases to what we are finding out. Then the earthquakes are intermittent and we have no idea what strength they will be etc... meaning that it is quite - if not not impossible - to correlate the data.

Oh - one of things was that the waves travel faster along faults that are parralel to the direction of motion and go slower through ones that are perpendicular. And this effect is sort of amplyfied if there are say lots of parrellel fualts such as along the mid ocean ridges. Measuring flow there is quiet important as there is hydrothermal perculation and stuff through the newely formed sea floor as it is hot and stuff - this affects mineral exchange and the such like. But during the working things out time he gave us I came up with the concept of using the earthquakes to tell if you where in a back arc basin, or near an accretionary prism, ie looking at the big big structures as they have different minerals and things in them (stolen straight from Wednesdays lecture). The girl I was sitting with said she had thought the same thing - the lecturer said we were coming up with good ideas.

Later on he said I was asking the right sort of questions too - though as the lecture ended up over running what with me getting excited over the way in which the earth or spheres in general can distort with motions and the like (yes I asked more questions) I think the rest of the class where about to kill me.

We got on to the heliosiesmics and wow! I think i actually got how they are detecting the sun-quakes. Now on the earth we have seismometers on the surface but the sun is a) humungous and b) too far a way and c) uber hot. But we have images in all sorts of wave lengths and the suns surface is in continous motion. The sun is a plasma which moves as a fluid and you can see the convection cells on the surface. You can take images and see how they change - think about it - surface that is further away from you such as that in a trough or valley (earthquakes are waves with peaks and troughs) will have a slight red shift to it as the wave gets stretched on route were as the peaks will be like mountains and nearer the earth or satallite depending were the detector is and be blue shifted compared to the base level surface colour (we are assuming constaint composition of the sun here.

This is cool as you can basically do the tomography tequnic and look at flow!

We also looked at solar flares and sunspots which has me a bit disturbed - is it me or does the behavour of sunspots becoming solar flares seem to suggest that the sunspots individually are magnetic poles? But that would make them a magnetic monopole which I thought could not exist?

Am I missing something here?

Anyway to my suprise I am actually now considering writing my second essay (its due in december) on helioseismics! I must be mad - but I found this really really interesting!