1853-1928

Hendrik Antoon Lorentz was one of the greatest scientists of his time. His work covered many fields of physics. However, his most outstanding contributions were to the theory of electromagnetism. Based on the Maxwellian framework, Lorentz proposed a universal theory of physics based purely on the concepts of electromagnetism. His fundamental postulates, which were independent of mechanical principles, were presented in “Inquiry into a Theory of Electrical and Optical Phenomena in Moving Bodies” published in 1895 in Dutch. Lorentz described the electromagnetic field in five equations for the first time in compact vector notation. The first four equations embodied the content of Maxwell’s theory, while the fifth equation described, what was called Lorentz force, connected continuous field with electricity. His discoveries prepared the ground for many of the developments in modern physics. Lorentz was one of the first to predict the existence of electrons. He explained the Zeeman effect, a change in spectral lines in a magnetic field. Lorentz further advanced the hypothesis of George Francis FitzGerald (1851-1901) that the length of a body contracts in the direction of its motion when it is moving. This phenomenon is now called Lorentz contraction. Lorentz is also well-known for Lorentz transformations which he introduced in 1904. Lorentz transformations are a set of mathematical equations that correlate space and time coordinates of one moving system to known space and time of another system. Lorentz transformations explained the experiment of Michelson and Morley and described the shortening of length the increase in mass and dilation of time of a moving body moving at a speed close to the velocity of light. This work influenced, and was confirmed by Einstein’s special theory of relativity. Lorentz did a great deal to found theoretical physics as an academic discipline in Europe. Lorentz was much influenced by Augustin Jean Fresnel’s (1788-1827) work. He admitted that it was through Fresnel’s work that he acquired clarity in thought and insight.

After the First World War, Lorentz strived hard towards reorganisation of international co-operations especially among scientists. He largely succeeded in his endeavours because of the undisputed prestige and respect that he enjoyed among scientists all over the world. Towards the end of his life he served as Chairman of the League of Nations’ Committee of Intellectual Co-operation. Lorentz was the President of the first Solvay Conference for Physics held in Brussels and he continued to be president of Solvay Conferences until his death.

Owen Williams Richardson (1879-1959) described Lorentz as “[A] man of remarkable intellectual powers…Although steeped in his own investigation of the moment, he always seemed to have in his immediate grasp its ramifications into every corner of the universe…The singular clearness of his writings provides a striking reflection of his wonderful powers in this respect…He possessed and successfully employed the mental vivacity which is necessary to follow the interplay of discussion, the insight which is required to extract these statements which illuminate the real difficulties and the wisdom to lead discussion among fruitful channels, and he did this so skilfully that the process was hardly perceptible.”

Lorentz was born on July 18, 1853 at Arnhem, the Netherlands. His parents were Gerrit Frederik Lorentz and Geeruide. Till the age of 13 he attended the Mr. Timmer’s Primary School in Arnhem. He then entered the first High School to be opened at Arnhem in 1866. In 1870, Lorentz entered the University of Leiden. He obtained his BSc degree in mathematics and physics in 1872 and then he returned to his native place Arnhem where he started teaching evening classes. Though he left the university but he continued to work for his doctorate degree.

In 1875, Lorentz obtained his PhD degree from the Leiden University. At the time of his getting PhD, he was just 22 years old. In his research work for his PhD dissertation, Lorentz refined the electromagnetic theory of Clerk Maxwell. Lorentz could provide better explanation for reflection and refraction of light. His doctoral dissertation was titled “The theory of the reflection and refraction of light.”

Lorentz remained at his home without taking any permanent profession even after receiving his doctoral degree. This was due to the fact that he was in dilemma over the choice of a career in physics or mathematics. In those days theoretical physics was an isolated academic pursuit. It was yet to emerge as a distinct scientific discipline of its own. In 1878, at the early age of 25, Lorentz was appointed Professor of Mathematical Physics at the Leiden University. The post, the first chair of theoretical physics in Holland, was newly created for him. He remained at the Leiden University till his retirement in 1912. This was in spite of the fact that he received offers of many academic appointments abroad. Lorentz engaged himself in developing a single theory to explain the relationship of electricity, magnetism and light. His main objective in developing such a unified theory was to refine the electromagnetic theory of Clerk Maxwell so that the relationship between electromagnetism and light can be explained. He proposed that the atoms might consist of charged particles (later termed as electrons) and the oscillations of these charged particles were the source of light. A consequence of Lorentz’s electron theory was that a magnetic field would affect the electron oscillations, and thereby the frequencies of the light emitted. Lorentz adopted the term ‘electron’ in 1899 and identified electrons with cathode rays. He showed how vibrations of electron give rise to Maxwell’s electromagnetic waves. In 1896, Lorentz jointly with Pieter Zeeman (1865-1943) explained the Zeeman effect whereby atomic spectral lines are split in the presence of magnetic fields. For this work they were jointly awarded the 1902 Nobel Prize in Physics. Lorentz’s ‘electron theory’ proved to be so successful that its failure to explain the photoelectric effect was a major clue to the need for quantum theory.

Lorentz is well-known for his suggested method of resolving the problems raised by the results of the experiments conducted by Albert Abraham Michelson (1852-1931) and Edward Williams Morley (1838-1923) in the 1880s to demonstrate the existence of hypothetical ether. Michelson-Morley experiment gave no indication that the Earth was moving through the hypothetical ether. He showed that if it was assumed that moving bodies contracted very slightly in direction of their motion then the observed results of Michelson-Morley experiment could be accounted for. FitzGerald also derived it independent of Lorentz. This phenomenon is now known as Lorentz-FitzGerald contraction. In 1904, Lorentz developed a firm mathematical description of this, the Lorentz transformation. Einstein later showed that this emerges naturally out of his special theory of relativity.

Lorentz presided over the first Solvay Conference in Brussels in 1911. The main objective of this conference was to look at the problems of having two different approaches in physics—classical physics and quantum physics. In his Presidential address at the opening ceremony of the conference, Lorentz observed: “In this stage of affairs there appeared to us like a wonderful ray of light the beautiful hypothesis of energy elements which was first expounded by Planck and then extended by Einstein and Nernst and others to many phenomena. It has opened for us unexpected vistas, even those, who consider it with a certain suspicion, must admit its importance and fruitfulness.” Lorentz himself never fully accepted the quantum theory. He believed that eventually the new theory would be fitted into the classical approach.

In 1912, Lorentz became the Director of research at the Teyler Institute at Haarlem. However, he remained honorary professor at Leiden and gave weekly lectures there.

Lorentz was elected a Fellow of the Royal Society in 1905. He was also the recipient of the Rumford Medal (1908) and Copley Medal (1918) of the Royal Society. In 1923, he was elected to the membership of the “International Committee of Intellectual Co-operations” of the League of Nations. Lorentz became its President in 1925.

Lorentz died on February 04, 1928. He was the most revered scientist of his time in the Netherlands. The Nobel Laureate Owen W Richardson, while describing Lorentz’s funeral, wrote: “The funeral took place at Haarlem at noon on Friday, February 10. At the stroke of twelve the state telegraph and telephone services of Holland were suspended for three minutes as the revered tribute to the greatest man Holland has produced in our time. It was attended by many colleagues and distinguished physicists from foreign countries. The President, Sir Ernest Rutherford, represented the Royal Society and made an appreciative oration by the graveside.” This description gives an indication the respect that Lorentz held in the Netherlands.

Lorentz’s contributions to the growth of physics and his greatness as a human being were beautifully summarised by Albert Einstein in his message delivered at Leiden in 1953 on the occasion of commemorating of the one hundredth anniversary of the birth of Lorentz. We quote here from this Einstein’s message: “At the turn of the century the theoretical physicists of all nations considered H. A. Lorentz as the leading mind among them, and rightly so. The physicists of our time are mostly not fully aware of the decisive part which H. A. Lorentz played in shaping the fundamental ideas in theoretical physics. The reason for this strange fact is that Lorentz’s basic ideas have become so much a part of them that they are hardly able to realise quite how daring these ideas have been and to what extent they have simplified the foundations of physics…Thanks to the generosity of the Leiden University, I frequently spent some time there staying with my dear and unforgettable friend, Paul Ehrenfest. Thus I had often the opportunity to attend Lorentz’s lectures which he gave regularly to a small circle of young colleagues after he had already retired from his professorship. Whatever came from this supreme mind was as lucid and beautiful as a good work of art and was presented with such facility and easy as I have never experienced in anybody else. If we younger people had known H. A. Lorentz only as a sublime mind, our admiration and respect for him would have been unique. But what I feel when I think of H. A. Lorentz is far more than that. He meant more to me personally than anybody else I have met in my lifetime.”

References

1 – Einstein, Albert. Ideas and Opinions. New Delhi: Rupa & Co, 1984.

2 – Dardo, Mauro. Nobel Laureates and Twentieth Century Physics. Cambridge: Cambridge University Press, 2004.

3 – Heilbron, J. L. (Ed.) The Oxford Companion to the History of Modern Science. Oxford: Oxford University Press, 2003.

4 – The Cambridge Dictionary of Scientists (Second Edition). Cambridge: Cambridge University Press, 2003.

5 – The Nobel Foundation, Nobel Lectures: Physics 1901-1921, Amsterdam: Elsevier, 1967.

6 – Dictionary of Scientists. Oxford: Oxford University Press, 1999.

7 – Parthasarathy, R, Paths of Innovators in Science, Engineering and Technology (Vol. Two), Chennai: EastWest Books (Madras) Pvt. Ltd, 2003.