I 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.
Did you get your physics education in high school or university? I only had to take one physics class in the USA at college for my major, quantum electrodynamics for electrical engineering but my professor wrote the textbook and I recall he went over each experiment starting from the fundamentals of our understanding of the basics of the atom, Newton's understanding of light at the time, double slit experiment, to Maxwell's equations, the Michelson Morley ether experiment, to deriving then proving experimentally proving general relativity and decomposing GR into Newtonian physics/other laws of electromagnetism, I am still in awe at the people just figuring this stuff out from first principles.
Anyways, I haven't read this (have it on hold at my library) but someone recommended this book on reddit
How to Make an Apple Pie from Scratch: In Search of the Recipe for Our Universe, from the Origins of Atoms to the Big Bang
https://www.publishersweekly.com/9780385545655
What’s the name of that textbook? It sounds really interesting.
Isaac Asimov wrote a couple books that follow the narrative of science from the beginnings up until the 80s or so, which I highly recommend. One is called Atom and is more focused on how we got to our “present” understanding of particles. There’s also one that takes a broader view, it’s something like History of Science (? not at my bookshelf right now).
There’s several books in this genre for math as well. IMO it’s a much better structure for pedagogy since we can piggy back the education on our natural wiring to care about narrative and mystery/puzzles.
It's like 800 pages, I haven't read it but I think I'll keep that one. Seems like it might be hard to find another physical copy. He was definitely prolific on a number of topics.
That was my Physics too, but Chemistry just completely glanced over the history. Same thing with Mathematics, no backstory of mathematicians. I guess that either 1. Physics History is short enough, well-recorded, or 2. Physicists really like teaching their history.
I mis wrote, he talked about the experiments done to verify general and special relativity. Michelson-Morley was one of them that sticks in my mind along with some traveling atomic clocks. We never recreated the experiments like some of the other commenters did in their classes.
I read Chasing the Molecule by John Buckingham recently and thoroughly enjoyed it! It give a good outline of the history of modern chemistry in a way that felt accessible but still thorough.
It also does a great job of explaining the different characters and their stories. Some little-known who moved chemistry forwards in profound ways, and others, very well-known, who through their loyalty to false theories ended up holding it back.
It's also a pretty short book when helps make it feel accessible.
So very true. The greatest science teachers understand the power that comes with the stories of scientific discovery.
Carl Sagan’s Cosmos and some of Richard Feynman’s best lectures come to mind as some of the most memorable examples, but I’m certain all the best teachers out there know to incorporate the historical and human aspects to bring the essential perspective and natural mnemonic anchors to otherwise “dry” subjects.
We did it with several hundred volts (DC, scary) in college and it was pretty fun collecting the data and watching the numbers fall out in excel doing the analysis.
As part of 9th grade biology we had to read "Microbe Hunters". The grades ahead insisted that it was awful and boring but I devoured the whole thing in a weekend. So thankful that it was part of the curriculum.
When I was a tutor, mostly doing math, when it came to polynomials and that range, I would trick my students into deriving the quadratic equation. It's not even a full page. Almost all of them finished with a strange expression, and then we had the little "it was always there, waiting for someone to find it" chat.
Some people care about the history, some don't. I find when people talk about astrophysics stuff, most of them do not know the history and ought to, because most of their interpretations fall into the "Yes, that was a question in the 1960s but eventually ..."
If you want one for relativity, I strongly suggest Was Einstein Right? by Clifford Will. It dates from 1986, so it is nearly forty years behind now, but it covers the many experiments and tests of relativities special and general.
In 1676 Roemer estimated the speed of light by timing the orbit of Jupiter’s moon Io, noting that as the Earth approached Jupiter, Io emerged from behind Jupiter a little earlier every day, and as the Earth traveled away from Jupiter it appeared a little later every day, with the time of day varying by 22 minutes over a year. Knowing the difference between the two distances, he reckoned that light travels that distance in 22 minutes, or 227 thousand km/s. The actual speed is about 300 thousand km/s. Not bad!
I always appreciate these stories about how very specific observations that most people would miss can give away far deeper details of the universe that many wouldn't even consider. Eratosthenes using shadows and figuring out the size of the earth within a few percent is another well known one.
"Rayleigh divided the volume of the oil by the area it covered, thus estimating the thickness of the oil film. 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.
This is how Lord Rayleigh became the first person to figure out a single molecule’s dimensions, many years before anyone could see such molecules."
That reminds me of the Millikan & Fletcher oil-drop experiment [0], which measured the charge of the electron.
In short, microscopic atomized oil droplets had their fall-time through air measured to figure out their volume, and then a known electric field was used to levitate them. The calculated charge-per-molecule clustered around multiples of a smaller value, which would be the charge of an individual electron.
For that to happen, you would have to be very unlucky: all of your measurements would have to be 2e, 4e, 6e, etc. If a 3e or 5e sneaked in there, you'd realize that the charge was e, not 2e. With enough measurements, you can be confident that you've hit all the expected multiples of the quantum.
In 1909 the results results were couched in some "elementary electric charge" quantity, since the now-familiar subatomic particle model (and the "electron") was still gaining acceptance.
I expect that the greater the number of trials, it becomes easier it is to detect a distinction between closer-multiples, and if at some point more trials stops changing the answer then you've likely converged on e, unless there's some new principle like "X-ray exposure only affects charge in in multiples of e greater than one."
> 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.
Rayleigh's experiment was actually trying to solve for the minimum thickness of oil required to stop some camphor shavings from moving around on the water. He never states it explicitly, but I think the assumption is that the minimum thickness required to stop the shavings' movement would be such that the oil volume 'just' covers the surface, ie. is 1 molecule thick everywhere and hence the shavings never touch water. I think he's specifically making a slightly more clever point about surface tension, but that's a little beyond me.
It feels intuitive that a thin fluid on a low-friction surface (like water) would spread out "as much as possible" given enough time. There certainly may be confounding factors, but it seems like a reasonable thing to pin as an "assumption" in a hypothesis. I.e. he didn't have to "know" - assumptions are OK, and I don't feel like this one is huge.
> It feels intuitive that a thin fluid on a low-friction surface (like water) would spread out "as much as possible" given enough time.
Most fluids do not behave this way in most circumstances, because of surface tension, so it's really not intuitive.
This experiments is one of the few ways you can get an accurate measurement. Many other fluids will either mix or end up as bubbles/blobs many orders of magnitude thicker than a molecule.
I'm confused, the blog wrote "known amount of water," so was it a closed little area like a bathtub? If you added a ton of oil wouldn't it spread out as much as possible aka 600 molecules thick or whatever?
Scientists frequently have to make assumptions in order to make progress.
Famous example is Darwin figured out that traits are inheritable by natural selection, and this is the driving force of evolution, without having any concept of the physical nature of DNA, or how genes could change (eg. by DNA mutation) to develop adaptations and thus make an organism more fit.
Perhaps at the time it was sufficient to define "molecule of oil" as "the height of the amount when spread maximally across the surface of water", and it just so happens that height is only 1 actual molecule
If there were multiple layers of molecules then the film would spread out over a wider area. With repeated experiments it would be clear that films are always an integer multiple of this thickness and never thinner.
> Seems questionable that Rayleigh would have known that oil molecules are hydrophobic on one end and hydrophilic on the other.
That's not a true thing, so it kinda doesn't matter. Surfactants (soaps, emulsifiers) have hydrophobic and hydrophilic ends. Oils are just straight up hydrophobic and nonpolar and don't have a water-loving end.
He certainly knew oil was hydrophobic. I don't think the hydrophilic nature was necessary for the logic.
If it was, I'm sure he knew that soap oils are both hydrophobic and hydrophilic and had ways of figuring out that soap oils consist of a single type of molecule and aren't a mixture.
Whatever possessed you to post that bilge, despite finding it fishy, is beyond me. In the future, you might choose to keep such interactions to yourself.
I 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?"
I don't think many people today would be able to propose the Michelson Morley experiment and then actually do it. It was truly heoric (and Michelson was a genius).
We did this oil/water experiment in freshman physics or chemistry lab. It was rushed, everybody just did the minimum, the teachers barely explained any of it, and then we moved on.
I agree. The Michelson Morley experiment reminds me of some difficult algorithms: simple only in hindsight, and implementation is _hard_ to do correctly.
Experiments are HARD. There is a joke among physicists that theoreticians are washed up by 35 but experimentalists don't even get started until 45.
To make a physics experiment work you have to be ridiculous about recording details and have a strong intuition. You have to design the experiment such that you can differentiate between "hypothesis wrong" and "equipment doesn't work" because you don't know the answer.
(For example: When they turned on LIGO for the first time, they almost immediately caught a great event. Huge victory party, right? Nope. They promptly ignored it assuming that something was wrong with the machine. And it was only after significant post analysis and correlation that they decided that it was a real event.)
It's by a guy called Don Lincoln and it's about how we established things like the existence of atoms, the speed of light, and many other fundamental things that are good to know.
It's also an audiobook, though the lectures are easier to follow.
We 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.
A few days ago, there was a HN post about surface acoustic wave filters, and a commenter mentions how inspired the inventor of it must have been(https://news.ycombinator.com/item?id=41604937).
> I love this story because it shows, at least anecdotally, how deep scientific insights can emerge from the simplest of experiments. It's a testament to the idea that you don't always need sophisticated equipment to unlock the secrets of nature — sometimes, all it takes is a drop of oil and a bit of ingenuity.
I went to a talk by a very old physicist. At the end of his talk, he said, recalling from memory, all of the great experiments of the past were done by nothing. If an experiment costs more than $100, I am out.
His setup has mud in a jar and bacteria in it which you can see with a simple microscope or handheld lens.
The credit for proving the existence of atoms is more often associated with Einstein's explanation of Brownian motion and Jean Perrin's experimental confirmation, even though earlier work by Lord Rayleigh, Benjamin Franklin, and others hinted at the molecular structure of matter.
Luckily it wasn't my grade that got this experiment as the practical exam in one of the National Physics Olympiads I went to... :) poor souls, most got answers orders of magnitude away.
These are the best kind of posts, where there's something I've never even heard of before. I never knew 'oiling the seas' was a thing, or that it (apparently?) works.
We did this same experiment in school, with a tiny pinprick of oil, estimating the volume of the drop as a sphere, and a small water tank, and then estimated the area of oil slick as a circle.
The 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...
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. (<1% error)
That's funny, thanks for sharing. I was watching his video where he's saying "you can see it right there, look how much calmer it is, it looks like ice" and was thinking "I don't know what he's talking about I don't see ... oh, that ice patch is water"
The actual manuscript from Rayleigh [1] explains it better: the area is the entire area of the vessel the oil was placed in, and the thing actually being measured was how much oil was required for it cover the whole area.
He used a fixed area (a 33 inch diameter bowl) and measured the weight of oil required to just about calm the entire water. That turned out to be 0.81 milligrams.
Some powder is added to the water, which covers the surface of the water but not the oil patch (which is circular). Then the oil patch diameter is measured.
When we did it in high school (70's) we just used compound that had a long chain (soap?) and only one end dissolved in the water. It was very easy to measure and calculate the size of the molecule . We had a series of these simple experiments. Another I recall was measure the speed at which certain volatile compounds moved through the air.
I definitely learned that all science doesn't have to involve complex equipment.
The original way was to cover the surface of a round bowl with oil. It certainly makes a lot more sense to me than trying to measure a floating disk of oil.
>"not more than a Tea Spoonful," according to his diary — Franklin poured it onto the agitated water. The oil spread rapidly across the surface, covering "perhaps half an Acre" of the pond and rendering its waters "as smooth as a Looking Glass."
I 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.
Did you get your physics education in high school or university? I only had to take one physics class in the USA at college for my major, quantum electrodynamics for electrical engineering but my professor wrote the textbook and I recall he went over each experiment starting from the fundamentals of our understanding of the basics of the atom, Newton's understanding of light at the time, double slit experiment, to Maxwell's equations, the Michelson Morley ether experiment, to deriving then proving experimentally proving general relativity and decomposing GR into Newtonian physics/other laws of electromagnetism, I am still in awe at the people just figuring this stuff out from first principles.
Anyways, I haven't read this (have it on hold at my library) but someone recommended this book on reddit How to Make an Apple Pie from Scratch: In Search of the Recipe for Our Universe, from the Origins of Atoms to the Big Bang https://www.publishersweekly.com/9780385545655
What’s the name of that textbook? It sounds really interesting.
Isaac Asimov wrote a couple books that follow the narrative of science from the beginnings up until the 80s or so, which I highly recommend. One is called Atom and is more focused on how we got to our “present” understanding of particles. There’s also one that takes a broader view, it’s something like History of Science (? not at my bookshelf right now).
There’s several books in this genre for math as well. IMO it’s a much better structure for pedagogy since we can piggy back the education on our natural wiring to care about narrative and mystery/puzzles.
You're referring to The History of Physics. An excellent read for a budding mind.
Asimov was incredibly talented.
I was looking at my parent's bookshelf and saw a book on Shakespeare and I recognized the author's name: Asimov!
https://en.wikipedia.org/wiki/Asimov's_Guide_to_Shakespeare
It's like 800 pages, I haven't read it but I think I'll keep that one. Seems like it might be hard to find another physical copy. He was definitely prolific on a number of topics.
That was my Physics too, but Chemistry just completely glanced over the history. Same thing with Mathematics, no backstory of mathematicians. I guess that either 1. Physics History is short enough, well-recorded, or 2. Physicists really like teaching their history.
> experimentally proving general relativity
Can you elaborate on that? What experiments did the professor perform?
I mis wrote, he talked about the experiments done to verify general and special relativity. Michelson-Morley was one of them that sticks in my mind along with some traveling atomic clocks. We never recreated the experiments like some of the other commenters did in their classes.
I read Chasing the Molecule by John Buckingham recently and thoroughly enjoyed it! It give a good outline of the history of modern chemistry in a way that felt accessible but still thorough.
It also does a great job of explaining the different characters and their stories. Some little-known who moved chemistry forwards in profound ways, and others, very well-known, who through their loyalty to false theories ended up holding it back.
It's also a pretty short book when helps make it feel accessible.
So very true. The greatest science teachers understand the power that comes with the stories of scientific discovery.
Carl Sagan’s Cosmos and some of Richard Feynman’s best lectures come to mind as some of the most memorable examples, but I’m certain all the best teachers out there know to incorporate the historical and human aspects to bring the essential perspective and natural mnemonic anchors to otherwise “dry” subjects.
Discovering the quantization of the charge of electrons sounds like something you'd be interested in: https://en.wikipedia.org/wiki/Oil_drop_experiment
We did it with several hundred volts (DC, scary) in college and it was pretty fun collecting the data and watching the numbers fall out in excel doing the analysis.
I highly recommend this book! https://www.goodreads.com/book/show/25238350-the-hunt-for-vu...
As part of 9th grade biology we had to read "Microbe Hunters". The grades ahead insisted that it was awful and boring but I devoured the whole thing in a weekend. So thankful that it was part of the curriculum.
When I was a tutor, mostly doing math, when it came to polynomials and that range, I would trick my students into deriving the quadratic equation. It's not even a full page. Almost all of them finished with a strange expression, and then we had the little "it was always there, waiting for someone to find it" chat.
Some people care about the history, some don't. I find when people talk about astrophysics stuff, most of them do not know the history and ought to, because most of their interpretations fall into the "Yes, that was a question in the 1960s but eventually ..."
If you want one for relativity, I strongly suggest Was Einstein Right? by Clifford Will. It dates from 1986, so it is nearly forty years behind now, but it covers the many experiments and tests of relativities special and general.
In 1676 Roemer estimated the speed of light by timing the orbit of Jupiter’s moon Io, noting that as the Earth approached Jupiter, Io emerged from behind Jupiter a little earlier every day, and as the Earth traveled away from Jupiter it appeared a little later every day, with the time of day varying by 22 minutes over a year. Knowing the difference between the two distances, he reckoned that light travels that distance in 22 minutes, or 227 thousand km/s. The actual speed is about 300 thousand km/s. Not bad!
I always appreciate these stories about how very specific observations that most people would miss can give away far deeper details of the universe that many wouldn't even consider. Eratosthenes using shadows and figuring out the size of the earth within a few percent is another well known one.
"Rayleigh divided the volume of the oil by the area it covered, thus estimating the thickness of the oil film. 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.
This is how Lord Rayleigh became the first person to figure out a single molecule’s dimensions, many years before anyone could see such molecules."
That reminds me of the Millikan & Fletcher oil-drop experiment [0], which measured the charge of the electron.
In short, microscopic atomized oil droplets had their fall-time through air measured to figure out their volume, and then a known electric field was used to levitate them. The calculated charge-per-molecule clustered around multiples of a smaller value, which would be the charge of an individual electron.
[0] https://en.wikipedia.org/wiki/Oil_drop_experiment
How can you make sure you don't end up with 2e as a result? (Or any other multiple)
For that to happen, you would have to be very unlucky: all of your measurements would have to be 2e, 4e, 6e, etc. If a 3e or 5e sneaked in there, you'd realize that the charge was e, not 2e. With enough measurements, you can be confident that you've hit all the expected multiples of the quantum.
In 1909 the results results were couched in some "elementary electric charge" quantity, since the now-familiar subatomic particle model (and the "electron") was still gaining acceptance.
I expect that the greater the number of trials, it becomes easier it is to detect a distinction between closer-multiples, and if at some point more trials stops changing the answer then you've likely converged on e, unless there's some new principle like "X-ray exposure only affects charge in in multiples of e greater than one."
You do. Thae size of the steps between the results is the “quantum” of a single transferable charge.
He did- he selected the lowest value, ignoring all the multiples.
Not ignoring the multiples; the multiples verify the result.
If you calculate the charge of one at 1e and you measure 2.5e, something went wrong. All values must be a multiple of the lowest.
> 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.
Blog post seems to have elided this point, but it did link the original paper which was quite short: https://www.damtp.cam.ac.uk/user/gold/pdfs/teaching/old_lite...
Rayleigh's experiment was actually trying to solve for the minimum thickness of oil required to stop some camphor shavings from moving around on the water. He never states it explicitly, but I think the assumption is that the minimum thickness required to stop the shavings' movement would be such that the oil volume 'just' covers the surface, ie. is 1 molecule thick everywhere and hence the shavings never touch water. I think he's specifically making a slightly more clever point about surface tension, but that's a little beyond me.
Camphor would release compounds that adjust the surface tension of water. So the oil would break that direct relationship.
It feels intuitive that a thin fluid on a low-friction surface (like water) would spread out "as much as possible" given enough time. There certainly may be confounding factors, but it seems like a reasonable thing to pin as an "assumption" in a hypothesis. I.e. he didn't have to "know" - assumptions are OK, and I don't feel like this one is huge.
> It feels intuitive that a thin fluid on a low-friction surface (like water) would spread out "as much as possible" given enough time.
Most fluids do not behave this way in most circumstances, because of surface tension, so it's really not intuitive.
This experiments is one of the few ways you can get an accurate measurement. Many other fluids will either mix or end up as bubbles/blobs many orders of magnitude thicker than a molecule.
I'm confused, the blog wrote "known amount of water," so was it a closed little area like a bathtub? If you added a ton of oil wouldn't it spread out as much as possible aka 600 molecules thick or whatever?
Or did he pour it into a huge lake or something?
Agreed. The experiment actually gives an upper limit on the size of a molecule in one particular dimension. Still a very useful result.
It isn’t necessarily an upper bound. The molecules might spread out more distant than their size.
In a very unlucky world, they can form a 2D net, with molecules instead of strings and a lot of tiny holes.
If this seams impossible, remember that when water freeze into ice, it expands to a 3D "net" with empty holes.
Wouldn't that provide an upper bound then? If the real size is equal to or less than the calculated size?
Scientists frequently have to make assumptions in order to make progress.
Famous example is Darwin figured out that traits are inheritable by natural selection, and this is the driving force of evolution, without having any concept of the physical nature of DNA, or how genes could change (eg. by DNA mutation) to develop adaptations and thus make an organism more fit.
Perhaps at the time it was sufficient to define "molecule of oil" as "the height of the amount when spread maximally across the surface of water", and it just so happens that height is only 1 actual molecule
If there were multiple layers of molecules then the film would spread out over a wider area. With repeated experiments it would be clear that films are always an integer multiple of this thickness and never thinner.
> How did he know that the film of oil was one molecule thick?
He didn't. It was an assumption
[flagged]
Seems questionable that Rayleigh would have known that oil molecules are hydrophobic on one end and hydrophilic on the other.
> Seems questionable that Rayleigh would have known that oil molecules are hydrophobic on one end and hydrophilic on the other.
That's not a true thing, so it kinda doesn't matter. Surfactants (soaps, emulsifiers) have hydrophobic and hydrophilic ends. Oils are just straight up hydrophobic and nonpolar and don't have a water-loving end.
He certainly knew oil was hydrophobic. I don't think the hydrophilic nature was necessary for the logic.
If it was, I'm sure he knew that soap oils are both hydrophobic and hydrophilic and had ways of figuring out that soap oils consist of a single type of molecule and aren't a mixture.
He used olive oil though, not a soap oil.
Olive oil is a soap oil.
No idea. I was curious myself and decided to ask our "guru". The answer seems a bit fishy
Whatever possessed you to post that bilge, despite finding it fishy, is beyond me. In the future, you might choose to keep such interactions to yourself.
> Cortesy of ChatGPT:
Can we not, please? At the very least not unless you personally have the knowledge to confirm that ChatGPT didn't make any mistakes, as it did here.
This should be a rule on hacker news.
Agreed. Everyone here knows how to use chatgpt. We come here for a different way to share, learn and interact.
I 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?"
I don't think many people today would be able to propose the Michelson Morley experiment and then actually do it. It was truly heoric (and Michelson was a genius).
We did this oil/water experiment in freshman physics or chemistry lab. It was rushed, everybody just did the minimum, the teachers barely explained any of it, and then we moved on.
I agree. The Michelson Morley experiment reminds me of some difficult algorithms: simple only in hindsight, and implementation is _hard_ to do correctly.
People still win Nobel prizes (LIGO, for example) using interferometers. It’s arguably the single greatest invention in experimental physics.
Experiments are HARD. There is a joke among physicists that theoreticians are washed up by 35 but experimentalists don't even get started until 45.
To make a physics experiment work you have to be ridiculous about recording details and have a strong intuition. You have to design the experiment such that you can differentiate between "hypothesis wrong" and "equipment doesn't work" because you don't know the answer.
(For example: When they turned on LIGO for the first time, they almost immediately caught a great event. Huge victory party, right? Nope. They promptly ignored it assuming that something was wrong with the machine. And it was only after significant post analysis and correlation that they decided that it was a real event.)
Very cool.
For more like this, check out this lecture series: https://www.thegreatcoursesplus.com/the-evidence-for-modern-...
It's by a guy called Don Lincoln and it's about how we established things like the existence of atoms, the speed of light, and many other fundamental things that are good to know.
It's also an audiobook, though the lectures are easier to follow.
We 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.
A few days ago, there was a HN post about surface acoustic wave filters, and a commenter mentions how inspired the inventor of it must have been(https://news.ycombinator.com/item?id=41604937).
That was this same fella!
> I love this story because it shows, at least anecdotally, how deep scientific insights can emerge from the simplest of experiments. It's a testament to the idea that you don't always need sophisticated equipment to unlock the secrets of nature — sometimes, all it takes is a drop of oil and a bit of ingenuity.
This can apply to many other fields too!
I went to a talk by a very old physicist. At the end of his talk, he said, recalling from memory, all of the great experiments of the past were done by nothing. If an experiment costs more than $100, I am out.
His setup has mud in a jar and bacteria in it which you can see with a simple microscope or handheld lens.
The credit for proving the existence of atoms is more often associated with Einstein's explanation of Brownian motion and Jean Perrin's experimental confirmation, even though earlier work by Lord Rayleigh, Benjamin Franklin, and others hinted at the molecular structure of matter.
Luckily it wasn't my grade that got this experiment as the practical exam in one of the National Physics Olympiads I went to... :) poor souls, most got answers orders of magnitude away.
These are the best kind of posts, where there's something I've never even heard of before. I never knew 'oiling the seas' was a thing, or that it (apparently?) works.
We did this same experiment in school, with a tiny pinprick of oil, estimating the volume of the drop as a sphere, and a small water tank, and then estimated the area of oil slick as a circle.
Yes, we did it in physics at school too, when we were 13 or 14 I think.
The 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. (<1% error)
https://en.m.wikipedia.org/wiki/Chronology_of_computation_of...
Note that pi to 40 digits is sufficient to calculate the circumference of the observable universe to subatomic precision.
I won’t trust this until I myself can calm an acre of water with a teaspoon of oil. (Or at least see a YouTube video of someone doing it)
YouTube video: https://www.youtube.com/watch?v=RST_ylwVrUw&t=1m27s
That's funny, thanks for sharing. I was watching his video where he's saying "you can see it right there, look how much calmer it is, it looks like ice" and was thinking "I don't know what he's talking about I don't see ... oh, that ice patch is water"
Semi off topic:
Interesting to look at picture of the text of the 1890 paper. That typesetting is almost the same as modern scientific papers.
Maybe Rayleigh had an early copy of LaTeX? ;-)
Thank Knuth for TeX or good scientific typesetting would be a nice thing the Victorians had.
How is the measurement for the area the oil has spread over performed? Visually or some other way?
The actual manuscript from Rayleigh [1] explains it better: the area is the entire area of the vessel the oil was placed in, and the thing actually being measured was how much oil was required for it cover the whole area.
[1] https://www.damtp.cam.ac.uk/user/gold/pdfs/teaching/old_lite...
He used a fixed area (a 33 inch diameter bowl) and measured the weight of oil required to just about calm the entire water. That turned out to be 0.81 milligrams.
Some powder is added to the water, which covers the surface of the water but not the oil patch (which is circular). Then the oil patch diameter is measured.
This was how we did this when we replicated this experiment in high school. I guess from the other responses here that this wasn't common?
When we did it in high school (70's) we just used compound that had a long chain (soap?) and only one end dissolved in the water. It was very easy to measure and calculate the size of the molecule . We had a series of these simple experiments. Another I recall was measure the speed at which certain volatile compounds moved through the air.
I definitely learned that all science doesn't have to involve complex equipment.
The original way was to cover the surface of a round bowl with oil. It certainly makes a lot more sense to me than trying to measure a floating disk of oil.
Related: Agnes Pockels’ experiments [0]
[0]: https://en.wikipedia.org/wiki/Agnes_Pockels
>"not more than a Tea Spoonful," according to his diary — Franklin poured it onto the agitated water. The oil spread rapidly across the surface, covering "perhaps half an Acre" of the pond and rendering its waters "as smooth as a Looking Glass."
What??
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