A hymn to energy

E=mc2 the story of the greatest discovery in history; David Bodanis. Translated from English: Yaniv Farkash. Keter Publishing, 296 pages, NIS 78

Dear Shoshani

Manuscript of the paper on E=mc2

If short modern poems, which contain an idea expressed succinctly, can resemble formulas in physics, as it sometimes seems to me, then the formula E=mc2 developed by Albert Einstein in his special theory of relativity in 1905 can be considered a song (hallel) for energy.

David Boudanis, the author, received basic training in the sciences, but preferred to work as a journalist and economic consultant, and in the book before us he describes in fluent and fascinating language the components and development of one of the most important formulas in modern physics.

Until the beginning of the twentieth century, two separate conservation laws were known for mass and energy. In any physical or chemical process that occurs in the system closed to the environment, the amount of these sizes did not change. It was Einstein who first pointed out, from purely theoretical considerations, that mass can turn into a huge amount of energy and vice versa - energy, for example from electromagnetic radiation, can turn into two particles with mass that separate from each other in a process known today as "pair production". Since the book is intended for a non-professional audience, the author offers no proof or explanation of the origin of the linking formula (a simple explanation is provided on the author's website).

The first two parts of the book review in detail each of the physical quantities and symbols appearing in the formula, while focusing on the personalities associated with their development. From this interesting review we learn that significant contributions to physics were made by personalities outside the scientific establishment. In the chapter on clarifying the concept of energy (p. 21 onwards), the author describes the contribution of Michael Farday, an apprentice bookbinder in London in the early 19th century, who, due to his great love of books, came to deep insights related to the concepts of energy and the electric field. The author explains the ability of a non-professional person to make such an important contribution to the development of physics, by saying that "in retrospect it became clear that Faraday's limited formal education was an advantage. This is not a common case; when a subject of scientific research is in advanced stages...the doors are locked, the articles become unreadable. But In these early days of understanding energy, things were different" (p. 24).

In the chapter reviewing the concept of mass, the story of Antoine Lavoisier, who was an accountant for 20 years, and in his investigation, which eventually led to the Law of Conservation of Mass, was only concerned with one day a week, which he called "the day of happiness". Einstein also, as we know, worked starting in 1902 as a third-rate patent clerk in Bern, and while doing this work he composed several scientific articles and conceived the basic ideas of the special theory of relativity. "Working at the patent office freed him from the duty of serial production of academic publications ('a temptation to superficiality', Einstein wrote, 'which only those with a strong character are able to resist') and allowed him to engage in his ideas as much as required" (p. 81

Another interesting aspect of the historical review in the book is the contribution of women to the development of physics, which is not adequately reflected in the scientific education system. How many physicists know, for example, that Cecilia Payne was the first to correctly read the spectrum of sunlight, and that based on this reading she determined that most of the material on this planet is hydrogen and helium?
In this work she challenged the theory that prevailed at the time, that the core of the sun is made of iron, a theory that was unable to explain the source of the sun's energy.
Cecilia Payne's conclusions were of crucial importance for understanding the source of the energy of the Sun and other stars. Today we clearly know that fusion processes of light nuclei into heavier ones take place in stars, for example the fusion of hydrogen into helium, or of helium into carbon, and the reduction in mass between the reactants of this reaction and its products becomes energy.

An equally important contribution was that of the Jewish chemist Lisa Meitner, who in 1938 offered Otto Hahn the correct theoretical analysis of the fission of the uranium nucleus, even though Hahn betrayed their friendship and arranged for her to be removed from the German institute where she worked when Hitler came to power. Two centuries earlier, the researcher Amelie de Chatela offered an explanation that the kinetic energy is proportional to the square of the speed, as Leibniz believed in the 17th century, and not as his contemporary Isaac Newton believed, that this energy is proportional to the speed to the first power.

The core of the book (parts 5-3) deals with the meanings of the famous formula and the results derived from it. The author describes in detail the problems that faced the Germans in the development of the nuclear bomb in World War II, and how the Americans managed to overcome them in their "Manhattan Plan". It is a shame that the author did not devote the same amount of attention to the description of the uses of the formula for the well-being of man and society, although there is a description in the book, in my opinion too brief, of some such interesting uses. In my opinion, it was also possible to expand more in the discussion of the importance of the formula in understanding the thermonuclear processes that provide the energy of the stars, including our sun, and its contribution in the development of models in astrophysics, such as the creation of black holes and the evolution of the universe until the end of generations. From my experience I know that these topics are very fascinating to many people. I think it would have been good to bring, if not in the body of the book, then in the notes, at least one example of a fusion process, for example of a deuteron and tritium into helium, and show, through a fairly simple use of the formula, what the energy is released from the fusion between them.

In some places the descriptions offered by the author are inaccuracies, perhaps due to the difficulty of explaining complex physical processes to the general public. Such is, for example, the description of Chandrasekhar's ideas in connection with the formation of black holes (p. 172 et seq.) or the argument on p. 53 that tries to justify the increase in the mass of a space shuttle whose speed approaches the speed of light (a more convincing explanation is provided in the comments on p. 215). Also in the discussion about the earth's gravity on page 217 there is an inaccuracy in the sentence "An apple, or any other object, falls in one second about 5 meters". As we know, there is an acceleration on the surface of the earth (about 10 m per second squared), so that only in the first second the body falls about 5 meters and then its speed increases and increases.

Although the book is popular in nature and intended for a wide readership interested in modern physics, professionals in the history of physics will also find it of some interest. The author invested a considerable effort in collecting a wide variety of scenes, in the expansion of topics from the body of the book with instructive notes, and in fascinating historical and philosophical explanations. Thus, for example, he brings up the dispute between Newton and Leibniz regarding the dependence of the energy of motion on speed and links this with the existence of God. As we know, Newton was imbued with religious faith and believed in the divine design of the world and its laws. Furthermore, he believed that God continuously supplies energy to the world. Indeed, in his opinion, if the energy of motion is characteristic of speed to the first power, then in the collision of two bodies whose velocities are opposite, all their energy of motion is lost, and therefore there is a need for a continuous renewal of the world's energy stock. The book contains many additional examples with thought-provoking philosophical and historical contexts.

Budanis ends his book with the sentence: "I really enjoyed writing this book" (p. 284). And to that I have nothing but to add: Thank you Mr. Budanis, I really enjoyed reading this book.

David Bodanis E = mc2, A Biography of the World's Most Famous Equation

Yakir Shoshani is a physics professor. His latest books "Thoughts on Reality" and "Thoughts on Reason" were published by the Broadcasting University - Ministry of Defense.

To purchase the book in Mithos - please click on the banner
https://www.hayadan.org.il/BuildaGate4/general2/data_card.php?Cat=~~~301410247~~~42&SiteName=hayadan

Leave a Reply

Email will not be published. Required fields are marked *

This site uses Akismet to filter spam comments. More details about how the information from your response will be processed.