Continue to invest in the UK's world class science base and develop strategies for commercialising more of that science.
This is what's being tossed around by the Government as the reason for the reorganisation (again) of the departments to give us the shiny new Department for Business, Innovation and Skills which will take over responsibility for science funding. The reaction from those scientists who've commented since the announcement this afternoon? 'We're doomed' seems to sum it up.
It has been pointed out before (I think Carl Sagan once answered a press conference question to this effect, but I can't recall where or when) that if you want commercially useful science, the one thing you should not do is attempt any kind of scheme for developing commercially useful science. You fund research, and new stuff comes along. A lot of it is only good for trivial things like discovering our place in the universe etc etc, but you get fancy spin-offs and everyone's happy.
More worrying, however, is when polititians say they want to fund commercially viable science, what generally happens is that everything without an immediately obvious material benefit gets cut. Short-sighted economically, for the reason above, but disastrous for science as a whole. I know these are times when the Government must try to save money, but there has to be more to life than just profit maximising.
It's not just confined to the current objects of my annoyance, but there does seem something awfully hollow about the present Government. They'll fund some cultural projects, but they don't seem to like them - they're just publicity events. They'll fund some scientific research, but they don't seem interested - it's just potential business capital.
Rant over.
Friday, 5 June 2009
Thursday, 9 April 2009
Efficient Area
Further to my post of units in science, here's a thought:
The efficiency of a car is measured in miles per gallon (or kilometers per litre, or miles per litre or whatever). That is, length travelled per volume of fuel consumed.
We can express this as a length divided by a length cubed - m / m³ if we're using SI. But this works out to be a reciprocal area, 1/m² .
So what's the meaning of this area that somehow describes the fuel efficiency of a car? It's the cross-sectional area of a pipe laid by the road containing stationary fuel such that the amount of fuel you pass is exactly enough to keep the car moving at the present speed.
The efficiency of a car is measured in miles per gallon (or kilometers per litre, or miles per litre or whatever). That is, length travelled per volume of fuel consumed.
We can express this as a length divided by a length cubed - m / m³ if we're using SI. But this works out to be a reciprocal area, 1/m² .
So what's the meaning of this area that somehow describes the fuel efficiency of a car? It's the cross-sectional area of a pipe laid by the road containing stationary fuel such that the amount of fuel you pass is exactly enough to keep the car moving at the present speed.
Saturday, 4 April 2009
Hammer Time
I've been away for a couple of weeks, happily bashing away at rocks in the West Country with my hammer. Spending a fortnight in the company of geologists does odd things to your brain - anyone who thinks the internet has a monopoly on memetic mutation hasn't encountered the running jokes that develop in science departments.
A list of stereotypical traits of geologists that seem to be true a disproportionate amount of the time:
1. Long hair and/or beard
2. Drinks real ale
3. Likes walking and camping
4. Likes folk music
5. Married to another geologist
On a similar subject, almost all the mathematicians I know speak - or are learning - Chinese (none of them actually are Chinese). Why the correlation, I wonder?
A list of stereotypical traits of geologists that seem to be true a disproportionate amount of the time:
1. Long hair and/or beard
2. Drinks real ale
3. Likes walking and camping
4. Likes folk music
5. Married to another geologist
On a similar subject, almost all the mathematicians I know speak - or are learning - Chinese (none of them actually are Chinese). Why the correlation, I wonder?
Saturday, 28 February 2009
Tuesday, 24 February 2009
Die? No!
'Early Tertiary dinosaurs' is a fairly controversial phrase to utter in the palaeontological community. It crops up now and again when dinosaur-like fossils crop up in deposits thought to be Cenozoic in age.
[Before I go any further, a word of explanation for those not in the know. The dinosaurs were predominant during the Mesozoic Era which came to an end about 65 million years ago, succeeded by the Cenozoic. The Tertiary refers to everything between then and the beginning of the current Ice Age, after which is the Quaternary. Tertiary and Quaternary are old terms and don't fit neatly into the nice modern hierarchical system of time divisions, but they're pretty convenient]
Now, non-avian dinosaurs are not found - at least, not found definitively - after the end of the Mesozoic, the so-called 'K-T boundary'. However, it's entirely feasible that they hung around for a little while longer; after all, the birds are still going strong and are themselves a variety of dinosaur, hence my use of 'non-avian dinosaurs' at the beginning of this paragraph.
However, we do occasionally find teeth and even sometimes bones in early Tertiary deposits that look dinosaurian. So we are faced with four possibilities:
1. Dinosaurs lasted notably longer than we previously thought.
2. They're not dinosaur remains.
3. They are dinosaur remains, but reworked from previous sediments. That is, they were washed out of older rocks as they eroded and were carried along to be included in younger layers.
4. The rocks are older than we thought.
Which of these is true likely depends on particular deposits of these remains. But I want to look at the problem itself and what it actually means.
Because it depends entirely on what you mean by 'K-T boundary'. We're so used to hearing confident dates for these things that frequently we forget what they mean in practice. And people use 'boundary' in so many ways. Such as:
But none of these really mean the same thing. Let us assume for the moment that this asteroid did hit at the date believed - a fairly solid proposal - and that it was what directly caused the mass extinction of the dinosaurs and various other groups. What does this mean for our Tertiary dinosaur hypothesis?
Well, not all of the dinosaurs would have died at once. The fact that some creatures survived is indicative of non-total destruction. Therefore, dinosaurs would almost certainly have struggled on for a little longer. Whether they did so for years or for millions of years; in tiny numbers or as marginal but notable populations we do not know. So if we defined the beginning of the Tertiary as the moment - or even the day or the year - of the impact then yes, there were Tertiary dinosaurs. Maybe not long-lasting, but they were there.
But this is something of a impractical definition. It's pretty obvious that the mass extinction wasn't instantaneous, so why not give the boundary a width as well as a location and define it by the extinction itself, as per the first bullet point above? Now things are more interesting. The presence of Cenozoic dinosaurs in this way of thinking would require one or more populations to survive not only the impact but the associated traumas and extinctions. Only if they then disappeared on their own, after the massive tide of deaths would they truly count as Tertiary. And this is the real nub of the question, because what people actually want to know is not what we call the point that dinosaurs disappeared, but did the dinosaurs actually become extinct as a group, or was it more complex than it might appear? Were they doomed from the moment of impact, or did some of them achieve stability afterwards only to be killed off for some other reason?
[Before I go any further, a word of explanation for those not in the know. The dinosaurs were predominant during the Mesozoic Era which came to an end about 65 million years ago, succeeded by the Cenozoic. The Tertiary refers to everything between then and the beginning of the current Ice Age, after which is the Quaternary. Tertiary and Quaternary are old terms and don't fit neatly into the nice modern hierarchical system of time divisions, but they're pretty convenient]
Now, non-avian dinosaurs are not found - at least, not found definitively - after the end of the Mesozoic, the so-called 'K-T boundary'. However, it's entirely feasible that they hung around for a little while longer; after all, the birds are still going strong and are themselves a variety of dinosaur, hence my use of 'non-avian dinosaurs' at the beginning of this paragraph.
However, we do occasionally find teeth and even sometimes bones in early Tertiary deposits that look dinosaurian. So we are faced with four possibilities:
1. Dinosaurs lasted notably longer than we previously thought.
2. They're not dinosaur remains.
3. They are dinosaur remains, but reworked from previous sediments. That is, they were washed out of older rocks as they eroded and were carried along to be included in younger layers.
4. The rocks are older than we thought.
Which of these is true likely depends on particular deposits of these remains. But I want to look at the problem itself and what it actually means.
Because it depends entirely on what you mean by 'K-T boundary'. We're so used to hearing confident dates for these things that frequently we forget what they mean in practice. And people use 'boundary' in so many ways. Such as:
- The Maastrichtian mass extinction event, associated with the disappearance of many forms of life, including the dinosaurs, ammonites, icthyosaurs etc.
- A point in the rock record marked by or correlated with a layer of iridium and shocked quartz thought to be the effect of a giant asteroid hitting the Earth at Chixulub. By extension, the point at which this asteroid hit.
- A stratigraphic boundary recognisable - though differently formed - in many parts of the world by change of depositional environment and/or fossil assemblage. Presumably associated with the above.
But none of these really mean the same thing. Let us assume for the moment that this asteroid did hit at the date believed - a fairly solid proposal - and that it was what directly caused the mass extinction of the dinosaurs and various other groups. What does this mean for our Tertiary dinosaur hypothesis?
Well, not all of the dinosaurs would have died at once. The fact that some creatures survived is indicative of non-total destruction. Therefore, dinosaurs would almost certainly have struggled on for a little longer. Whether they did so for years or for millions of years; in tiny numbers or as marginal but notable populations we do not know. So if we defined the beginning of the Tertiary as the moment - or even the day or the year - of the impact then yes, there were Tertiary dinosaurs. Maybe not long-lasting, but they were there.
But this is something of a impractical definition. It's pretty obvious that the mass extinction wasn't instantaneous, so why not give the boundary a width as well as a location and define it by the extinction itself, as per the first bullet point above? Now things are more interesting. The presence of Cenozoic dinosaurs in this way of thinking would require one or more populations to survive not only the impact but the associated traumas and extinctions. Only if they then disappeared on their own, after the massive tide of deaths would they truly count as Tertiary. And this is the real nub of the question, because what people actually want to know is not what we call the point that dinosaurs disappeared, but did the dinosaurs actually become extinct as a group, or was it more complex than it might appear? Were they doomed from the moment of impact, or did some of them achieve stability afterwards only to be killed off for some other reason?
Wednesday, 31 December 2008
Not So Crystal Clear
It is exceedingly apparent today that ice defines our world to a great degree. Here I am, about three thousand miles from the North Pole and it's still sub-zero outside my window. Hardly suprising given that we're in the middle of an ice age, although admittedly people tend not to think about it like that.
Ice is a mineral * , and that's something else that seems a little odd, though if you think about it there's no reason why not - it's a crystalline solid with a characteristic composition, it's just that it has a nice low melting point. Actually it's a family of minerals, because all the water molecules can pack together in different ways, giving the different types of ice different physical properties.
The reason snowflakes are hexagonal (unless you break them, obviously) is because pretty much all the ice you'll encounter on Earth is of the hexagonally symmetric variety. What I mean by this is best illustrated by a diagram of how the molecules link to each other:
The hexagonal symmetry is pretty plain looking down this axis. This is going to affect the way the crystal grows and therefore the overall appearance. It's one of the most useful principles for mineralogists that the macroscopic properties of a crystal are indicative of its microscopic structure. In this case, the growth faces of the snowflake have to be arranged with hexagonal symmetry looking down this axis.
(Incidentally, there is no reason why two snowflakes cannot look the same. But given the vast number of possible flakes and the endless variations in initial conditions the chances of finding two identical ones are minimal)
But as I mentioned earlier, there is more than one type of ice and I don't simply mean that in the sense of frost/rime/sheet ice/wrong type of snow. They're all the hexagonal form of ice, ice I-h as it's know. In all, there are fifteen different structures (if one includes amorphous ice - 'ice glass' as it is also known, more on the unconventional use of the word 'glass' another time) with one more predicted but not yet observed definitively. These other forms are only really observed in unusual circumstances or in conditions not encountered on Earth.
Some of them have unexpected properties indeed. Ice XI is 'ferroelectric' - it establishes an electric dipole with a positive end and a negative end, analogous to a magnet with a north and south pole. Ice VI and VII also do odd things with electricity, although in more abstract ways.
This multiplicity of forms masquerading as pure simplicity - for what could appear purer or more regular than clear ice? - is a common theme in mineralogy. It is also a prime example of the importance of interaction in explaining the properties of materials - all the ices have the same chemical formula, the same chemical properties. But the interactions between the identical molecules produce a dazzling variety of possibilities, something mirrored in the infinity of forms of the silica minerals. To drive the point home, over 60% of all the rocks that make up the crust of earth is silica, the same stuff of which glass and quartz are made.
* The Greek for for ice, 'krystallos', gives us our word 'crystal'.
Ice is a mineral * , and that's something else that seems a little odd, though if you think about it there's no reason why not - it's a crystalline solid with a characteristic composition, it's just that it has a nice low melting point. Actually it's a family of minerals, because all the water molecules can pack together in different ways, giving the different types of ice different physical properties.
The reason snowflakes are hexagonal (unless you break them, obviously) is because pretty much all the ice you'll encounter on Earth is of the hexagonally symmetric variety. What I mean by this is best illustrated by a diagram of how the molecules link to each other:
The hexagonal symmetry is pretty plain looking down this axis. This is going to affect the way the crystal grows and therefore the overall appearance. It's one of the most useful principles for mineralogists that the macroscopic properties of a crystal are indicative of its microscopic structure. In this case, the growth faces of the snowflake have to be arranged with hexagonal symmetry looking down this axis.(Incidentally, there is no reason why two snowflakes cannot look the same. But given the vast number of possible flakes and the endless variations in initial conditions the chances of finding two identical ones are minimal)
But as I mentioned earlier, there is more than one type of ice and I don't simply mean that in the sense of frost/rime/sheet ice/wrong type of snow. They're all the hexagonal form of ice, ice I-h as it's know. In all, there are fifteen different structures (if one includes amorphous ice - 'ice glass' as it is also known, more on the unconventional use of the word 'glass' another time) with one more predicted but not yet observed definitively. These other forms are only really observed in unusual circumstances or in conditions not encountered on Earth.
Some of them have unexpected properties indeed. Ice XI is 'ferroelectric' - it establishes an electric dipole with a positive end and a negative end, analogous to a magnet with a north and south pole. Ice VI and VII also do odd things with electricity, although in more abstract ways.
This multiplicity of forms masquerading as pure simplicity - for what could appear purer or more regular than clear ice? - is a common theme in mineralogy. It is also a prime example of the importance of interaction in explaining the properties of materials - all the ices have the same chemical formula, the same chemical properties. But the interactions between the identical molecules produce a dazzling variety of possibilities, something mirrored in the infinity of forms of the silica minerals. To drive the point home, over 60% of all the rocks that make up the crust of earth is silica, the same stuff of which glass and quartz are made.
* The Greek for for ice, 'krystallos', gives us our word 'crystal'.
Saturday, 6 December 2008
A Colourful Tale
Yeah, it's been a long time since the last post. Blame endless piles of work and similar commitments. Anyway, I'm going to talk about light and colour today, via a rather oblique approach. Bear with me.
Here we have two photographs taken down a microscope of a sample of kimberlite, a rock found frequently in South Africa - it's where all those diamonds come from. This sample doesn't have any, though, I chose it to point out the grains of olivine. They're the highly cracked ones in the upper-left, brightly coloured in the right-hand photo.
Now, the coloured photo has not been digitally altered in any way. The colours are not made up - they are there naturally given the right conditions.
What happens is this - a petrographic microscope has two polarising filters, one above the sample which is fixed in place and one above that can be put in and out, called the analyser. A polarising filter, by the way, is a little screen that lets light through only if it is vibrating in the correct orientation.
Any light that's vibrating at the correct orientation (ie. parallel to the grid) goes straight through, any that is perpendicular gets totally blocked and any that is somewhere between the two gets broken down into a parallel component and a perpendicular component. The polarised light then proceeds to travel through the crystals that make up the rock.
As you can probably see, the presence of the analyser creates some possibilities. If it has the same orientation as the polariser, it might as well not be there, as it does nothing that has not already been done. And if it is perpendicular, it'll just block out everything that got through the first time.
As it happens, the analyser is always fixed perpendicular to the polariser. And yet somehow we get an image of the rock, in many bright colours. Something funny must be going on.
What's happening is this: when the newly polarised light passes into a crystal, it encounters obstruction from the atoms, electrons etc. Crystals, by their nature, have internal structure and some directions are going to be more obstructed than others. Without going into the physics of this too deeply, the asymmetrical obstruction creates a twisting effect on the light - the polarisation it has when it goes in is not necessarily the polarisation it has coming out again. So we get some light that's capable of passing through the analyser after all.
What about the colours, though? Well, another effect of the crystal on the light is that some of it gets bent and comes out with a delay:
This means that those rays in the above diagram are going to be out of phase (the peaks and troughs in their vibration will not match up properly). But remember that white light is composed of many different wavelengths (ie colours) of light all mixed up. They won't all match up or fail to match up at the same time - different colours will be transmitted depending on the orientation of the crystal. This is what makes those 'birefringence colours' in the olivine, you're seeing the composite of all the wavelengths that managed to get through without cancelling themselves out.
(The reason you only see the birefringence with the analyser in is that it filters out the component that doesn't get twisted around - in the first picture the birefringence is lost in all the other light that's allowed through to your eyes.)
Colour seems so intuitive a lot of the time - everything has its colour and it's so easy to see how they combine and contrast. But our brains are fooling us, colour isn't as fundamental as we think. Colour is our mind's way of interpreting and representing different wavelength of light. Normally the wavelengths we see coming from an object relate to what that object is good at absorbing - it's colour is the composite of whatever is not absorbed. But not always.
The sky, of course, isn't actually blue. Not really, not in the sense that, say, blue ink is blue. But it looks blue to us because the light from the Sun is scattered differently depending on its colour. Blue light is scattered a lot, red hardly at all. So the red light all seems to be coming from the Sun, while the blue light seems to be coming from all over the sky. Sunsets are often red because the extra air (and smoke etc, this being close to the horizon) scatter the red light enough to dominate the area.
But surely most things do have real colour, barring a few peculiar set-ups like the crossed polars and sky? The photo on the left - that shows how olivine really looks, doesn't it? Well, not really. Remember me saying that certain orientations of the crystal slow down light more than others? Well, they also absorb light more than others. And with polarised light, this means that certain positions of the sample are going to absorb different light than others. If you spin the slide as shown in the first picture around, you would see the colour of the grains twinkling and fading between shades of yellow, brown and colourless.
Colour, I'm afraid, is not truthful. Like so many other things, it tells us things about the world around us. But we have to learn the language it's talking in to understand the tale.
Here we have two photographs taken down a microscope of a sample of kimberlite, a rock found frequently in South Africa - it's where all those diamonds come from. This sample doesn't have any, though, I chose it to point out the grains of olivine. They're the highly cracked ones in the upper-left, brightly coloured in the right-hand photo.Now, the coloured photo has not been digitally altered in any way. The colours are not made up - they are there naturally given the right conditions.
What happens is this - a petrographic microscope has two polarising filters, one above the sample which is fixed in place and one above that can be put in and out, called the analyser. A polarising filter, by the way, is a little screen that lets light through only if it is vibrating in the correct orientation.
Any light that's vibrating at the correct orientation (ie. parallel to the grid) goes straight through, any that is perpendicular gets totally blocked and any that is somewhere between the two gets broken down into a parallel component and a perpendicular component. The polarised light then proceeds to travel through the crystals that make up the rock.As you can probably see, the presence of the analyser creates some possibilities. If it has the same orientation as the polariser, it might as well not be there, as it does nothing that has not already been done. And if it is perpendicular, it'll just block out everything that got through the first time.
As it happens, the analyser is always fixed perpendicular to the polariser. And yet somehow we get an image of the rock, in many bright colours. Something funny must be going on.
What's happening is this: when the newly polarised light passes into a crystal, it encounters obstruction from the atoms, electrons etc. Crystals, by their nature, have internal structure and some directions are going to be more obstructed than others. Without going into the physics of this too deeply, the asymmetrical obstruction creates a twisting effect on the light - the polarisation it has when it goes in is not necessarily the polarisation it has coming out again. So we get some light that's capable of passing through the analyser after all.
What about the colours, though? Well, another effect of the crystal on the light is that some of it gets bent and comes out with a delay:
This means that those rays in the above diagram are going to be out of phase (the peaks and troughs in their vibration will not match up properly). But remember that white light is composed of many different wavelengths (ie colours) of light all mixed up. They won't all match up or fail to match up at the same time - different colours will be transmitted depending on the orientation of the crystal. This is what makes those 'birefringence colours' in the olivine, you're seeing the composite of all the wavelengths that managed to get through without cancelling themselves out.(The reason you only see the birefringence with the analyser in is that it filters out the component that doesn't get twisted around - in the first picture the birefringence is lost in all the other light that's allowed through to your eyes.)
Colour seems so intuitive a lot of the time - everything has its colour and it's so easy to see how they combine and contrast. But our brains are fooling us, colour isn't as fundamental as we think. Colour is our mind's way of interpreting and representing different wavelength of light. Normally the wavelengths we see coming from an object relate to what that object is good at absorbing - it's colour is the composite of whatever is not absorbed. But not always.
The sky, of course, isn't actually blue. Not really, not in the sense that, say, blue ink is blue. But it looks blue to us because the light from the Sun is scattered differently depending on its colour. Blue light is scattered a lot, red hardly at all. So the red light all seems to be coming from the Sun, while the blue light seems to be coming from all over the sky. Sunsets are often red because the extra air (and smoke etc, this being close to the horizon) scatter the red light enough to dominate the area.
But surely most things do have real colour, barring a few peculiar set-ups like the crossed polars and sky? The photo on the left - that shows how olivine really looks, doesn't it? Well, not really. Remember me saying that certain orientations of the crystal slow down light more than others? Well, they also absorb light more than others. And with polarised light, this means that certain positions of the sample are going to absorb different light than others. If you spin the slide as shown in the first picture around, you would see the colour of the grains twinkling and fading between shades of yellow, brown and colourless.
Colour, I'm afraid, is not truthful. Like so many other things, it tells us things about the world around us. But we have to learn the language it's talking in to understand the tale.
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