Desktop version

Home arrow Engineering arrow The dark side of technology

Source

Information loss from technology of materials

From politicians and scientists to the media, we are misled that technology is improving the world and everything is getting better. In the case of the ways we have written information (everything from shopping lists to love letters and science), this is definitely not correct. Indeed, the opposite is closer to the truth. The following examples will give a short catalogue of some of the writing media used over the last few thousand years and hint how long they might survive, and some of the reasons for their loss and decay. In every case, there is some trade-off between the ease and speed of writing and the length of time it could survive in that format.

Stone carving needs skill, strength, and patience, especially if it is intended for long-term survival, as then the choice of rocks will favour hard-wearing ones that do not readily weather and crumble. That means hard to carve. So carvings in granite have survived quite well, and there are many inscriptions on old buildings that are easily legible. The text is often on a large scale and limited content, but in favourable climates a carving on a building saying, ‘This is the palace of the great King Og, ruler of the universe’ can look impressive and last far beyond any memory of Mr Og. There are stone carvings from the earliest literate civilizations, so survival times of, say, 10,000 years are feasible. Aggressive climates and the use of softer stones to allow faster, cheaper carving clearly do not match this survival. A trip around any UK church graveyard will show some headstones are still legible after 100 or 200 years, but many others of the same age have been etched away in the weather, and eroded into a blur.

The obvious problem with stone carvings is that they are expensive to make, heavy, and not very portable, so are best suited for use at a fixed location—not items to be sent by post. Storage in kinder climates increases their chances of survival, as does being buried in a protective layer of sand. The case of the Rosetta Stone fragment indicates that it is possible to inscribe a lot of text on a material such as basalt and it is clearly legible a few thousand years later.

Considering stone carving is ideal, as it links writing speed and quantity of information, and shows that some examples survive, whereas a high proportion of stone tablets are lost, broken, or eroded. Overall, this means there is a typical ‘half-life’ where half the items existing at any one moment are likely to survive for this period of time. The concept of a half-life is familiar in science as the nuclei of radioactive elements (such as uranium or potassium) have a mixture of weights because they contain slightly different numbers of protons and neutrons (although they are chemically uranium or potassium). Some proton and neutron mixtures are unstable, and statistically half of them fall apart at a very precise rate. The time for the loss of half of the unstable ones is called the half-life. But the pattern of a half-life for survival is the same elsewhere, even if we are discussing writing on materials that gradually decay.

Stone is inanimate, so this view of life expectancy of materials is not the same as the way we think about human life expectancy. For humans reaching adulthood in the UK, we can normally estimate the percentage that may survive until 70 (the classic three score and ten years). Somewhat surprisingly, by the time we reach 90, the inanimate half-life pattern sets in. Survival statistics beyond 90 suggest for a group of 90-year-olds approximately half are likely to reach 91, and of those survivors 50 per cent reach 92, etc. To any 90-year-olds reading this, I am sorry to say this means only one in a thousand are likely to reach a century.

At this end phase, the model of a ‘half-life’ is close to that of the loss of information with an inanimate ‘half-life’, or of the decay of radioactive elements. Of the many materials used for writing, stone is clearly the best choice for long-term survival, as for hard stones a half-life of carved information may be a few thousand years. Faster writing became possible by incising lines into clay tablets and then letting them dry or be baked. This was the classic start of cuneiform writing. Survival was good, but the clay tablets were more easily broken or lost as they tended to be small portable items. Nevertheless, the concept of a half-life for clay tablet survival may still suggest a number of, say, a thousand years. Many more stone tablets were written than big stone carvings, so overall more may have survived (even with a shorter half-life).

By around 2000 BC, much faster writing techniques started to become possible by writing with inks on papyrus and paper. Bonuses included greater writing speed, light weight, ease of storage and transport, and for immediate usage, the materials would probably outlast a typical human lifetime of the period. For documents stored in dry and arid tombs in Egypt (inside protective stone boxes), many will have decayed, but overall a few have survived to the present day. The problems of failure are decay of the papyrus, attack by insects, fading of the inks, or destruction by dampness. Overall, this means carefully stored items may have a half-life of 1,000 or 2,000 years, but the general documents would vanish within 100 or so years.

The white-hot technology of writing materials moved to using animal skins, which have, confusingly and variously, been called vellum and parchment. As before, they were excellent for faster writing with inks and survival for transport, and, in good containers, a few have survived up to the present day. Fading of inks and destruction by bacteria and bugs probably sets a half-life at a few hundred years, but again, so many were written that a few have survived several half-lives and survived 1,000 years. Modern technology can slightly increase the legibility of the scripts that have faded, as often viewing them in infrared light offers a better contrast than for the original viewing of the ink in visible daylight. Vellum has not gone out of fashion, as the British Acts of Parliament are written on vellum precisely to offer long-term stability and legibility.

In 2016, there were proposals to move from vellum to an entirely electronic storage system. This change might have offered some initial speed advantage for the storage copy, but fortunately wisdom prevailed with the realization that electronic formats and software are highly transient. So access to an electronic primary store might only be measured in decades, not centuries. Electronic transmission and distribution of the laws is of course routine. (Later in the chapter, I will return to this topic with more comments on vellum and its importance for the Domesday Book.)

Examples of carefully preserved writing include political documents, such as the record of property owned by people in England after the Norman invasion. This 1086 book, called the Domesday Book, has been cherished, so it gives a distorted and extended view of the normal survival half-life of such writings. Other high-profile documents such as the Dead Sea Scrolls have been found (in very poor condition) from the first century BC. These are at the extreme end of many half-lives for the materials used.

The Dead Sea Scrolls are an interesting example of a technology with a short survival time, as the scrolls were in metal containers described as being made of bronze. Bronze (for most of us) is a hard alloy of copper and tin, which was widely used, corrodes to form a surface protective layer, and was valuable in sword making and armour. Bronze items have survived because of their protective coating. Bronze Age metallurgy was in fashion for more than 1,000 years. By contrast, the containers for the Dead Sea Scrolls were of arsenic bronze (i.e. copper and arsenic). It had some good properties and was probably no more difficult to make, but during the production the melt liberated large quantities of toxic arsenic vapour. The life expectancy of working in an arsenic bronze smithy was remarkably short, and it was highly unlikely to be a skill maintained in a family business. Arsenic bronze went out of fashion.

Modern style paper manufacture started in China around the first century BC, reached the Islamic world by the eighth century, and continued westward. The move from writing to various forms of printing on paper speeded up duplication of information transfer. Paper offers a good writing speed and a material that was more readily produced than parchment and vellum, but with a compromise of a shorter survival time. As with early items, the inks were also liable to fade or attack the paper. For example, many medieval black inks were made from acorn galls, which have rather high iron content. The iron gives a good black contrast, but chemically it attacks the paper. So the centres of loops (as in an o or p) could drop out. Many types of paper fade in sunlight or crumble. Because of the large quantity of printing (e.g. mass production of books), examples have survived up to the present. However, for one-off specific and normal documents, the average life expectancy had dropped to, say, a century or so. In the last century, typing paper damage could occur from the impact of the keys. Fading of the inks is still a problem, and much more recently many current warranties and guarantees printed on till receipts are valueless, as they will have faded long before the guarantee expires.

 
Source
Found a mistake? Please highlight the word and press Shift + Enter  
< Prev   CONTENTS   Next >

Related topics