This was the first Interlude, describing the history of risk analysis and safety, important concepts in engineering that are often overlooked by science, math, and even business folks.
|image by babykrul (Gölin Doorneweerd) via rgbstock.com|
Lasers are relatively new, but the idea of safety--and how to quantify it--is not. All technology comes with risks, and one of the most ancient sets of law, Hammurabi's Code, showed the consequences of unsafe technology (like buildings) by outlining punishments for builders whose houses collapsed. However, figuring out how to make things safe took time.
Step 1: Make It WorkThe first step in designing safe technology was to create working technology: for example, builders had to figure out how to make buildings that actually stayed standing! In ancient Egypt, engineers such as Imhotep (c. 27th century BC) developed new construction methods and materials, eventually earning the title of the royal chief of engineering. Once experienced builders learned what worked, they passed those methods on. Imhotep wrote an encyclopedia of architecture that served as the definitive text for Egyptian builders for thousands of years. Likewise, in ancient Rome, Vitruvius's De Architectura (Ten Books on Architecture, c 15 BC) provided guidelines for buildings, hydraulics, aqueducts, roads, and even construction and war machines, and gave instructions for taking required measurements so that future builders could replicate his results.
How did these early engineers figure out what worked? They started with the Goldilocks method of "too much" or "too little," focusing on a qualitative understanding of construction rather than specific numbers. For example, in ancient China, the Kaogong ji (The Records of Examination of Craftsman, c. 210 BC), an instruction manual for building houses, vehicles, and weapons, described how to make an arrow: "The feathers at the end of the shaft are installed in three directiosn [...] When the feathers are too many, the arrows will slow down; when the feathers are too few, the arrow will become unstable."
Step 2: Do It ConsistentlyOnce engineers figured out how to make things work in general, they were able to start thinking about numbers. By quantifying how to build something, they began to quantify how to build it safely as well. In ancient Greece, records of a building constructed by Socrates (c. 341 BC) show early building requirements: "He shall set the joints against each other, fitting, and before inserting the dowels he shall show the architect all the stones to be fitting, and shall set them true and sound and dowel them with iron dowels, two dowels to each stone..." In 12th century China, the Yingzao Fashi (Treatise on Architecture Methods or State Building Standards) laid out very specific instructions for building a foundation: "For every square chi, apply two dan or earth; on top of it lay a mixture of broken brick, tile and crushed stones, also two dan. For every five-cun layer of earth, two men, standing face to face, should tamp six times with pestles, each man pounding three times on a dent..."
These specific, quantified safety guidelines are the roots of modern building codes. For instance, after the great fire of London in 1664 destroyed many poorly constructed buildings, Parliament enacted building regulations to ensure that new buildings were constructed properly. Today, we have many regulations around our technology--not just our buildings, but also water and gas pipes, electricity, telephones, and even contact lenses. Each warning label represents research that was done to determine the safe operating parameters for the device or system.
If you'd like to learn a bit more about lasers and light, take a look at the LASER Classroom MOOC course, Bringing STEM to Light: Teaching About Light and Optics. And LASER Classroom has a number of free light lessons as well which you might like.
- "Archery in Ancient China." China Archery. 29 November 2009. Web 2 Jan 2017. <http://www.chinaarchery.org/archives/tag/kao-gong-ji>
- "History of Building Codes." City of Neenah. Web 2 Jan 2017. <https://www.ci.neenah.wi.us/wp-content/uploads/2015/02/BuildingCodeHistory.pdf>
- "Architecture of the Song Dynasty." Wikipedia. Web 2 Jan 2017. <http://en.wikipedia.org/wiki/Architecture_of_the_Song_Dynasty>