July 2011 archive

Book review: “In defence of History” by R.J. Evans

evansI’ve been interested in the history of science for some time, as a result of hanging around with historians on twitter I have been led to historiography – the study of history and its methods. This has brought me to "In Defence of History" by Richard J. Evans. It provides an opportunity to compare the ways of the historian with those of my area of science.

In his introduction Evans makes clear the book is a response to postmodernist criticism of historical practice. I was also amused to note that he cites a source as saying that historians were resistant to philosophising about their subject and criticism of their methods. As a scientist it sometimes feels as if other academic disciplines, such as philosophy and history, are on a crusade to "help" science with their criticism – this has never felt at all supportive or helpful. What this book makes clear is that one shouldn’t lump all such outsiders into one hostile blob!

It becomes clear through the book that postmodernism is not really a single thing. The core is the idea that all things are text, and that an external, objective world is less relevant – this idea originated with linguists and philosophers who were relatively unconcerned with the external world. As a somewhat hostile outsider Evans probably does not provide the best introduction to postmodernism, although he does acknowledge that ideas from postmodernism have been useful in the study of history and historical study.

As a by-product of this defence Evans gives a clear survey of what history is and what it claims to do.

The book begins with a history of history: raising first pre-modern styles of history, such as the chronicle and the morality tale of Gibbon’s "Decline and Fall of the Roman Empire". Leopold von Ranke is cited as the father of the modern method, that’s to say the inspection of contemporary documents in the historical record using them to identify causes for historical events and "facts". Here the distinction is made between the primary sources and secondary sources. For Ranke the key subject of history was politics, a view that held sway for many year but more recently has been receding. The key to the historical method therefore is hunting down original documentation and reading it with a mind to its original purpose and the context of other documents of that period with a care not to be caught out by changes in language and unspoken purposes.

Evans also identifies the crisis in history following the First World War, a stark reminder to historians that predicting the future was tricky although Evans does not sign up to the idea that history is at all about predicting the future. There’s an interesting parallel here between Toynbee’s "A study of history" which tried explicitly to make laws of history for predicting the future and Asimov’s Foundation series of novels, which are based on precisely this idea. Predicting future events sets a high barrier for successful prediction, some fields of science face similar challenges such as in seismology – we can say an awful lot about earthquakes but exactly where and when are not amongst the things we can say. For these fields it’s typical to talk about the probabilities of events and the statistics of large numbers of events.

One thing that struck me was the statement that history was a scientific, imaginative and literary exercise, the first two are things that a scientist would sign up to for their own field immediately, but literary? For sciences such as the one I trained in, physics, students are scarcely asked to string words together. Exam questions are largely a case of putting a sequence of calculations together. My own writing is a reflection of this lack of training.

At one point Evans spends time trying to motivate the idea that history is a science, this seems to me an empty discussion – once you’ve decided whether or not history is a science what are you going to do? Put on a labcoat?

Since Ranke’s time history has diversified immensely with the increasing focus on non-political history such as social history and an appreciation of a wider range of themes , I find this liberating since my interest in history is primarily in "people like me", therefore social and scientific, rather than political.

In contrast to any scientific research I know the political beliefs, defined broadly to include race, gender and sexuality, have a strong bearing on historical research with fields driven to support currently political agendas and the political leanings of the researcher a subject of comment. The same goes for nationality with many European historians focused very much on their own nations and with a distorted view of their importance. It’s very difficult to find parallels in scientific research, to stretch a point you can perhaps look at genetic and brain imaging studies of homosexuality. There is a degree to which there exist national styles of scientific research which have varied with place and time but this research driven by the political agendas of the researcher feels alien to a scientist.

When doing battle with the postmodernists the work of a scientist is easier than that of a historian, since ultimately the usefulness of science is measured by tangible outputs, by impact. If postmodernism increases tangible outputs then it is welcomed into the fold, if it doesn’t (and I don’t believe it does) then it isn’t. Science is tied down by reality which is always there for a return visit, with new methods, in case of dispute. History on the other hand is always flowing past, with no chance of return.

An interesting note on style is the forthright criticism of other historians through the book, and also in the afterword where he addresses his critics in detail and at length. This type of writing is rarely seen in science, that’s not to say the thoughts do not exist just that such discussions are left to the bar, or other informal locations.

I found this book immensely thought provoking because it describes the inner workings of history from the point of view of a practioner, making a striking contrast with my own workings as a scientist.

The Two Cultures

It feels that there are two cultures growing up in the world of work, that of the public and the private sectors. If you believe reports in the news, public sector workers have gold-plated pensions and vast salaries for which they do very little, and the private sector is filled with the venial moneygrabbers who can provide no service to the public, and are actively intent on harming them.

I worked in the almost-public university sector, and now in the private sector – albeit in a very large company. The similarities are quite striking: both are subjected to continual change as the result of the appointment of a new ruling clique, and often operate in Byzantine bureaucratic systems.

These days, in the private sector, my tenure is clearly not secure and never has been, despite continuing success the number of people employed in my company has decreased by over a half since 2000. I receive a bonus, or variable-pay, it is variable and it is not pensionable. 

Last week many public sector workers were on strike over their pensions.

Comparisons with private sector pensions miss the point: in the public sector 90% of full-time workers have a pension, in the private sector only 43% of the full-time workforce have a pension [source]. The glib answer to this is that we should attempt to improve the pensions of all workers. However, we should understand why pensions are not a given in the private sector.  

Consider the nature of the organisations involved: the UK government has been around for hundreds of years, and we can anticipate it will do so similarly for hundreds of years. It also has a good credit record, if we are owed money by the government there is a good chance that we’ll get because at any time the government has a sizeable tax base on which it can call. As employees of the government we can expect substantial job security. A pension plan based on 1/80ths of income accrued per year actually seems a plausible bet: you can still expect to serve a substantial fraction of that with one public employer. It’s not the same in the private sector.

For most companies 40 years is an unimaginable period of time, as it is for their employees. In 40 years many successful companies will have lived out their lives, only a few such as the one I belong to, last longer. In the recent past private pension funds have collapsed leaving their members with nothing. As a university lecturer I could quite reasonably look forward to being employed as a university lecturer for the rest of my working life. As an industrial research scientist my time horizon is about 5 years, and actually it is entirely plausible that we will all be called to a meeting tomorrow to discover that the site I work on is to be closed.

That’s the deal for big organisations, public and private but there is a third group: Have you tried to get a plumber, or similar skilled, self-employed worker recently? If you have you’ll have found that they’re remarkably available at the moment, that’s because they have no work and when they have no work they don’t get paid. The same is true for many small businesses and self-employed people. It’s not like my job, or any job in the public sector where there may be a pay freeze for for a few years. For these people recession and a drop in the GDP doesn’t just mean a pay freeze, it means a substantial drop in income – that’s what a drop in GDP is, it really means that a whole load of people are getting noticeably less than they did the previous year. The recent recession in the UK led to a drop in GDP of around 5%. The effects on me, in a big company, and those in the public sector are relatively small, so the impact on this other group are larger than the headline.

Meanwhile the company I work for is attempting changes to our pension scheme: a few years ago the final salary scheme was closed to new entrants, this year they have proposed to close the scheme for current members. The company’s stated policy is to go towards a defined contributions scheme, although that hasn’t happened yet. For people like me this means an expected loss in the value of their pension of around 20%. So, despite some misgivings as to the use to which they put their political fund (of which I will attempt to opt-out), I have joined the union.

Power to the people!

Computational Photography

Lightfielddemo

Lytro, Inc, a technology spin-off company founded by Ren Ng, have been in the news recently with their announcement of a re-focusable camera: take one “image”, and change where the focal plane lies after the fact. This is illustrated in the images above, generated from a single shot from the prototype camera. As you move from left to right across this sequence you can see the focus shifting from the front left of image to back right.I saw this work a few years ago at the mighty SIGGRAPH conference, it comes out of a relatively new field of “computational photography”.

All photography is computational to a degree. In the past the computation was done using lenses and chemicals, different chemical mixes and processing times led to different colour effects in the final image. Nowadays we can do things digitally, or in new combinations of physical and digital.

These days your digital camera will already be doing significant computation on any image. The CCD sensor in a camera is fundamentally a photon-counting device – it doesn’t know anything about colour. Colour is obtained by putting a Bayer mask over the sensor, a cunning array of red, green and blue filters. It requires computation to unravel the effect of this filter array to make a colour image. Your camera will also make a white balance correction to take account of lighting colour. Finally, the manufacturer may apply image sharpening and colour enhancement, since colour is a remarkably complex thing there are a range of choices about how to present measured colours. These days compact cameras often come with face recognition, a further level of computation.

The Lytro system works by placing a microlens array in the optical train, the prototype device (described here) used a 296×296 array of lenses focusing onto a 16 million pixel medium format CCD chip, just short 40mmx40mm in size. The array of microlenses means means that for each pixel on the sensor you can work out the direction in which it was travelling, rather than just where it landed. For this reason this type of photography is sometimes called 4D or light-field photography. The 4 dimensions are the 2 dimensions locating where on the sensor the photon lands, and the direction in which it travels, described by another two dimensions. Once you have this truckload of data you can start doing neat tricks, such as changing the aperture and focal position of the displayed image, you can even shift the image viewpoint.

As well as refocusing there are also potentially benefits in being able to take images before accurate autofocus is achieved and then using computation to recover a focused image.

The work leading to Lytro was done by Ren Ng in Marc Levoy’s group at Stanford, home of the Stanford Multi-Camera Array: dispense with all that fiddly microlens stuff: just strap together 100 separate digital video cameras! This area can also result in terrible things being done to innocent cameras, for example in this work on deblurring images by fluttering the shutter, half a camera has been hacked off! Those involved have recognized this propensity and created the FrankenCamera.

Another example of computational photography is in high dynamic range imaging, normal digital images are acquired in a limited dynamic range: the ratio of the brightest thing they can show to the darkest thing they can show in a single image. The way around this is to take multiple images with different exposures and then combine together. This seems to lead, rather often, to some rather “over cooked” shots. However, this is a function of taste, fundamentally there is nothing wrong with this technique. The reason that such processing occurs is that although we can capture very high dynamic range images, displaying them is tricky so we have to look for techniques to squish the range down for viewing. There’s more on high dynamic range imaging here on the Cambridge in Colour website, which I recommend for good descriptions of all manner of things relating to photography.

I’m not sure whether the Lytro camera will be a commercial success. Users of mass market cameras are not typically using the type of depth-of-field effect shown at the top of the post (and repeated ad nauseum on the Lytro website). However, the system does offer other benefits, and it may be that ultimately it ends up in cameras without us really being aware of it. It’s possible Lytro will never make a camera, but instead license the technology to the big players like Canon, Panasonic or Nikon. As it stands we are part way through the journey from research demo to product.