Hi everybody, I'm Sam, and this will be my first contribution to the blog! (cue applause) It will not be a physical modeling exercise; instead I will be writing a little bit about about paradigm shifts in a series of a few posts. I hope it will provoke some interesting discussion. "But Sam," you ask, "Isn't 'paradigm shift' just a buzzword that people use to sound important?" Well, maybe, but it's also useful phrase used to describe a substantial change in the way something is done. Consider, for example, THE METRIC SYSTEM (many details from Wikipedia) In 1791, in the wake of revolution, France became the first country to adopt the recently developed metric system. Since then, every nation in the world has officially adopted the metric system except Liberia, Burma, and the United States. It is the standard measurement system for most physical science, even in the US (as far as I know, no other unit system even has a measurement for quantities like electric field or magnetic field) (also, when I say metric, I of course include cgs and mks and ignore systems that are not meant for measurement, like natural units and Planck units). It has the advantages of easy unit conversion (1 km = 1000 m vs 1 mile = 5280 ft, a value which I had to look up from Yariv's post), and lack of ambiguity in units (mass = kg, force = N vs mass = lbs_mass or stones, force = lbs_force). The strong preference of scientists for the metric system is evident from past experiences: From CNN, September 1999: "NASA lost a $125 million Mars orbiter because a Lockheed Martin engineering team used English units of measurement while the agency's team used the more conventional metric system for a key spacecraft operation" This story also illustrates the equally strong preference of engineers for the English system. Ah, and herein lies the problem. You see, when the metric system was first adopted in Europe, it created a standardized unit system. This proved useful to merchants selling their wares by weight, but more relevant to myself as a scientist, it provided a means for creating scientific recipes, for providing the utterly essential aspect of reproducibility to scientific experiments. However, now the standardization exists even with the English system, given a simple unit conversion. But why not adopt the metric system to avoid situations like the Mars orbiter and make me less confused when I cross the border to Canada and see speed limit signs telling me to do 80? Because it would be too huge of a paradigm shift. Allow me to illustrate my point. One of the most (if not the most) strongly affected groups by a change in measurement systems is manufacturers, ie people who make stuff. I will use a typical example of a manufacturer, the kind who I interact with in my lab: the noble machinist (keep in mind that machinists are very important, as they are required to make many, many products). If you have ever worked with a machinist in the states, chances are he or she will be totally confused if you try to give them dimensions in millimeters (I have done this, and they weren't very happy with me because it meant they had to convert all the dimensions I gave them into English). It would be extremely difficult to retrain people who have used the English system all their lives. It would be like learning a new language. Inevitably, it would cause a large number of mistakes. More significantly, they would have to get ENTIRELY new equipment. Every machine shop would have to completely replace their tools (drill bits, screwdrivers, wrenches etc) and materials (standardized sizes of bolts, nuts, sheet and bulk material, pipes, connectors, cables, etc etc). You could say, "Come on, it wouldn't be so bad! Listen, we could gradually phase out the old English equipment and just make everything in metric from now on!" However, I would counter that this is not a realistic plan. For starters, there's the problem of having to keep around two sets of equipment (one for the old English stuff and one for the new metric stuff), which would require double the space and double the maintenance. Second, there would be compatibility issues between new and old equipment (e.g. my old 3/4" ipod port wouldn't mate with my new 2 cm connector). Third, the previous two problems would likely be around for a long time, considering the age of some of the equipment that I've seen in labs and elsewhere. And I haven't even mentioned the economics. If basic parts manufacturers (the people who make the screws, the bolts, and the sheet metal that will later be made into products) began to offer metric parts (now that I think about it, maybe they already do?), I doubt anybody would buy them. It would cost them too much to replace all their machinery infrastructure. There would be no market for them. Maybe you would then ask "Well, what if the government made everybody switch to metric?" Well, other than the backlash this would cause towards whichever administration suggested this, it would likely hurt and maybe even bankrupt companies who were forced to switch. As far as I can tell, it would definitely hurt the US economy in the short term (but it might help other countries who could sell their metric wares here) and not help it at all in the long term. To me, the economic loss (not to mention the difficulty in convincing the US population to swallow the change) outweighs the advantages of switching. At this point, exhausted from my challenging you at every turn, you may finally say, "Well hey, SPEAKING of Canada, they changed to the metric system only in 1973. How did THEY do it??" The answer is that, well, they didn't. Not entirely anyway. Sure, the country may package food and make road signs in metric (which the US could probably do, if people could somehow be convinced to go along with it), but in fact their engineering materials, which mostly come from the states, are still in English units. Even Canada couldn't justify completely converting to the metric system Which just goes to show how difficult it is to pull off a paradigm shift. Next time, I'll present an example of a paradigm shift that I think COULD work.