The Scientific Method

While perusing an old issue of Geophysical Research Letters, a journal that publishes research in a wide area of physics: geophysics, atmospheric physics, space physics, planetary physics, etc., I ran across the following paper

What’s interesting about this article is that it is an excellent example of one piece of the scientific method in action. From the introduction,

“Measurements of carbon dioxide … have been made at Mauna Loa … since 1958 by Scripps … One objective … has been to document global-scale secular CO₂ trends. A duplicate, but quasi-independent, program has been underway since June 1974.”

Already the Scripps Institution of Oceanography had been measuring the CO₂ concentrations on Mauna Loa since 1958 and had seen an increase of 1.14 ppm (parts per million) per year. As is par for the course, scientists don't rely on one measurement of an important quantity, they seek "reproducible results." In this case, a different method was used by NOAA's Geophysical Monitoring for Climatic Change (GMCC) program to measure the same CO₂ concentration. Their result is shown here:

There is obviously an annual variation, but superposed on that is a "secular" increase, that is, one that is monotonic. It keeps on increasing. Even though it is only two years, this secular increase agrees with the earlier result.

What did the earlier result look like? This:

Again, there's a secular increase superposed on an annual variation. Peterson et al. have this to say about the earlier data:

"... the year-to-year increases were quite variable, from less than 0.5 to more than 2.0 ppm. At this time, the GMCC and Scripps records cannot be absolutely compared because of calibration problems..."

So, while the two methods were in general agreement, it was difficult to compare two measurements using completely different methods. In any case, more measurements were made, and an absolute comparison was achieved, at least to a level that was consistent with the uncertainties in the original observations.

The scientific method in action!

The Joy of Mathematical Proofs

I just received a new physics textbook that I ordered online - yes, I know, I don't need any more physics textbooks - and, as usual, no matter how familiar the material, I can always find something to learn that I didn't know.

This book is Matter in Motion: The Spirit and Evolution of Physics, by Ernest S. Abers and Charles F. Kennel, two UCLA professors. I was a students in Abers's quantum mechanics classes, and Kennel was in the plasma physics group, so I knew them both, although I hadn't known that they had written a book in 1977 for their "Physics for Non-Science Majors" class. I discovered the book while perusing the July 1977 issue of Physics Today while looking for another article (but that is another story, perhaps to be written about in a future post).

The review praised the book for not trying to do too much, and successfully dispelling "the widely held misapprehension that science consists of little more than a vast collection of uncontestable facts meticulously gathered and catalogued by individuals distinguished primarily by their ability to repress their emotions completely." They extend their discussion of the history of physics to the pre-Galileo period, where "Greek and medieval science finally get their day in court." That is, Abers and Kennel show how the Greeks obtained their results, rather than simply telling you.

My two favorites (that I have come across so far) are a simple proof of the Pythagorean theorem (one that they claim is essentially the same as the original) and a neat proof that there are only five regular solids. I've already posted about Euler's formula

F + V - E = 2

in August 2014 when I discussed Zometools. I mentioned then that there were at least 20 different proofs. Now, I don't have a classical math background. In fact, I'm one of the physicists that avoid as much math as possible, not because I don't love it, but because I like to use it rather than play around with it for its own sake. However, the latter is sometimes lots of fun. Back in 2014 I learned one of those proofs. And Abers & Kennel use Euler's formula to prove that there are only 5 regular solids (also known as Platonic solids: tetrahedron, cube, octahedron, dodecahedron, icosahedron).

So, now that I can prove some things, does that make me a mathematician?

Walter Elsasser "Memoirs of a Physicist in the Atomic Age"

Memoirs of a Physicist in the Atomic Age by Walter M. Elsasser
My rating: 4 of 5 stars

Elsasser was the founder of the dynamo theory of the Earth's magnetic field, and also had a successful career in other areas of physics, nuclear physics in Paris with the Joliot-Curies, for example, as well as meteorology. He was prolific, and published many journal articles in these areas. In his later life he turned to biology, and wrote three books on biophysics that never were quite accepted by the biological community.

In this book, he gives a more personal view of famous physicists of the early 20th century (Curie, Born, Oppenheimer, Wigner, Schroedinger, etc) than the well-known histories by Gamow and Segre - i.e., less physics - but interesting and enjoyable. His philosophical ideas I sometimes could not follow (or agree with), but the fact that he interacted professionally with so many famous physicists made for an interesting life - and an interesting read.

One scene that depicted 1922 Germany was especially eye-opening. While I knew that Philipp Lenard (Nobel Prize Physics 1905) was a strong supporter of the Nazi party, I didn't realize the extent to which this permeated his lectures, and the extent to which anti-Semitism had quickly escalated after World War I. Elsasser describes his first physics lecture at the University of Heidelberg like this:

“Every seat in the hall was taken. In walked Professor Lenard wearing an impeccably tailored suit; to his left breast there was fastened a silver swastika of gigantic proportions, perhaps ten centimeters square. This was most unusual, if one remembers that in spite of war and revolution, Germany had then still remained a place of law and order. A distinguished senior professor was most certainly not expected to brandish symbols of political extremism in class. But the students thought otherwise. They applauded intensely. They clapped, and then they shouted; they kept on clapping and shouting, on and on and on. How long this continued I cannot say precisely, but it was certainly the most dedicated and loudest ovation I ever witnessed in my life, before or after."

The recent (2017) biography on Einstein on the National Geographic channel, "Genius," depicts a similar scene in one of Lenard's lectures. There, he refuses to cancel class for the funeral of the assassinated Jewish politician, Walther Rathenau, and instead lectures to supportive students about the need to abolish the "Jewish physics of relativity" and return to "pure German physics."

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UPDATE: In Jeremy Bernstein's biography Einstein, he describes anti-Semitic (and anti-Einstein) activity even earlier, in 1920:

"In 1920 an anti-Einstein League was formed in Germany, and it offered substantial sums of money to anyone who would write refutations of Einstein's work. On August 24, 1920, the League sponsored a meeting in the Berlin Philharmonic Hall, which Einstein himself attended, where swastikas and anti-Semitic pamphlets were on sale, at which Einstein and his work were attacked. A few of his colleges respond in a letter to the 'Berliner Tageblatt' and a few days later Einstein himself wrote an angry letter, also published by the 'Berliner Tageblatt' --- which deeply shocked Ehrenfest, who seemed to feel that Einstein should have ignored the matter as unworthy of his attention. From this time on, until he finally left Germany in 1932, Einstein and his work were the targets of a steadily mounting campaign."