As November 2015 approaches and the celebrations of 100 years since Albert Einstein’s publication of The General Theory of Relativity kicks into full gear, it is easy to forget his other great achievements. This year also marks the 110th anniversary of Einstein’s so called “miracle year” of 1905 when he published papers on the following subjects:
- The photoelectric effect
- Size and number of atoms in a solution
- Brownian motion
- Special relativity and a subsequent further paper on the same subject and introducing the small matter of e=mc2.
The least celebrated of these great papers is the second in respect of the size and number of atoms; however, although maybe the least well known by the public it holds an Einstein record and has important influences for a number of industries.
The paper, entitled “A New Determination of molecular Dimensions”, (subject to some minor improvements) was the paper that Einstein submitted to the University of Zurich on the 20th July 1905 for his Doctorate, which he was to receive on the 15th January 1906.
What the paper described was a technique for calculating the size and number of molecules (atoms) in a solution. He did this in a mathematical calculation for the behaviour of sugar molecules in a solution and how this affects the measurable properties of the solution. He was finding a new way of getting results using liquids alone as against previous methods of obtaining the size and number of molecules in a solution from the kinetic theory of gasses.
Why should we be interested in this subject? Well, there are three reasons:
- It was the work for which Einstein became a Doctor, so it is of biographic interest.
- It is the most cited paper from Albert Einstein. What does this mean? In 1979 ( to mark the centenary of Einstein’s birth) researchers carried out a survey of citations (in papers published between 1961 and 1975) of all science papers published before 1912. Of the top eleven, four were by Einstein and the top was this paper.
- It has widespread applications where the suspension of particles in liquids is used from industries as varied as the dairy industry, the study of pollution and the behaviour of liquid cement.
This paper is another example of the way in which Albert Einstein affects our world, in this case on a practical and important level.