In 1870, Lord Rayleigh used oil and water to calculate the size of molecules
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Re: In 1870, Lord Rayleigh used oil and water to calculate the size of molecules
#2I love articles like this. I feel like too often in science education (at least my science education) that laws and theories are presented as just something that you need to memorize, when in my opinion the stories of how things were originally discovered and figured out is eminently more fascinating and inspiring. Like I remember having to learn all of these biochemical pathways, but I left school with nary a clue as to how these pathways were uncovered in the first place.
Thanks for submitting! Would welcome suggestions for any other publications on how scientific theories were first discovered.
Re: In 1870, Lord Rayleigh used oil and water to calculate the size of molecules
#3The page is timing out for me, but is it the inverse problem of the time when Steve Mould/Matt Parker measured the unknown quantity π, but already assuming a size of the molecules? Presumably Lord Rayleigh already had a at least a good order-of-magnitude approximation of pi...
Re: In 1870, Lord Rayleigh used oil and water to calculate the size of molecules
#4> Assuming that the oil formed a single layer of molecules — a monolayer — then the thickness of the oil film is the same thing as the length of one oil molecule.
How did he know that the film of oil was one molecule thick?
It feels like a huge assumption to me, but maybe this blog post left something out.
Re: In 1870, Lord Rayleigh used oil and water to calculate the size of molecules
#5I would have loved to have had a course in school about "The Design of Scientific Experiments." One that described the processes of landmark historical experiments from antiquity onward, and challenged students throughout: "Given this set of constraints, how would you design and execute an experiment to estimate the size of the Earth? Disprove phlogiston and luminiferous aether? Measure the speed of light?"
Re: In 1870, Lord Rayleigh used oil and water to calculate the size of molecules
#6We recreated this experiment in one of my university physics classes. It was a lot of work, and our results weren't nearly as good, but it was instructive and interesting. The equipment requirements were completely reasonable for an undergrad physics lab. I highly recommend giving it a try if you can.
Re: In 1870, Lord Rayleigh used oil and water to calculate the size of molecules
#7> Assuming that the oil formed a single layer of molecules — a monolayer — then the thickness of the oil film is the same thing as the length of one oil molecule. How did he know that the film of oil was one molecule thick? It feels like a huge assumption to me, but maybe this blog post left something out.
Agreed. The experiment actually gives an upper limit on the size of a molecule in one particular dimension. Still a very useful result.
Re: In 1870, Lord Rayleigh used oil and water to calculate the size of molecules
#8> Assuming that the oil formed a single layer of molecules — a monolayer — then the thickness of the oil film is the same thing as the length of one oil molecule. How did he know that the film of oil was one molecule thick? It feels like a huge assumption to me, but maybe this blog post left something out.
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Re: In 1870, Lord Rayleigh used oil and water to calculate the size of molecules
#9The page is timing out for me, but is it the inverse problem of the time when Steve Mould/Matt Parker measured the unknown quantity π, but already assuming a size of the molecules? Presumably Lord Rayleigh already had a at least a good order-of-magnitude approximation of pi... https://www.youtube.com/watch?v=lmgCgzjlWO4
By 1870 pi was known to several hundred decimal digits, for something like this calculation where you have other large sources of error Archimedes approximation from 2 millennia earlier would probably be fine. (https://en.m.wikipedia.org/wiki/Chronology_of_computation_of...
Re: In 1870, Lord Rayleigh used oil and water to calculate the size of molecules
#10> Assuming that the oil formed a single layer of molecules — a monolayer — then the thickness of the oil film is the same thing as the length of one oil molecule. How did he know that the film of oil was one molecule thick? It feels like a huge assumption to me, but maybe this blog post left something out.
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