Hendrik Lorentz and his links with the Accademia dei Lincei and Italy
Short talk by Frits Berends, Professor emeritus of Theoretical Physics at the University of
Leiden, during a visit of members of the Royal Holland Society of Sciences and
Humanities to the Accademia Nazionale dei Lincei (7 September 2016).
At this occasion it is a pleasure to say a few words on the Dutch physicist Hendrik
Lorentz. He lived from 1853 to 1928. On one hand he was a member of the Royal Holland
Society of Sciences and Humanities. On the other hand, he became a foreign member of
the Accademia dei Lincei in July 1902, a cleverly chosen moment since a few months later
he turned out to be the 1902 Physics Nobel Prize laureate.
What were his greatest successes? Before most physicists did so, he recognized the
great value of Maxwell’s theory of electromagnetism which made the startling claim that
light was an electromagnetic wave. Lorentz improved and extended Maxwell’s theory,
amongst others he suggested in 1878 the presence of small charged particles inside
molecules and atoms. They were later called electrons. With that assumption he could
explain amongst others the well-known color splitting of light in a prism which Maxwell
couldn’t. That electrons really exist in matter was demonstrated by his former student, the
experimental physicist Pieter Zeeman in 1896. He shared the Nobel Prize with Lorentz.
Looking back in 1918 at the introduction of the electron, Lorentz said: “I have been
very lucky with it. Thanks to experimental and theoretical research by many physicists
electrons have greatly surpassed the expectations which one initially could have. In those
days one couldn’t foresee that they would be building blocks of the atoms, that they
would be seen freely forward flying, that one would be able to count them and could
determine both their charge and mass.” Now hundred years later, one may add that our
daily life depends on electrons.
In Lorentz’ studies of electromagnetism he had also faced a serious problem – the
constancy of the speed of light irrespectively whether one moves to or from a light source.
He could only solve this paradox by making the revolutionary assumption that lengths
change in moving systems. This he did in 1892. Thus he paved the way for the theory of
relativity which Einstein published in 1905. One would then expect that scientific contacts
would soon be established between the two, but for four years there was no interaction at
all. That changed because of an event which took place here in Palazzo Corsini. Lorentz
had been invited to the 1908 International Mathematics Conference organized by the
mathematician Vito Volterra, member of this Accademia, later also foreign member of the
Holland Society. In his talk Lorentz proved that Planck’s theory of quanta created in 1900
was incompatible with the classical theory of electromagnetism. Einstein read this in the
proceedings, admired the proof, wrote a letter to Lorentz and a lifelong interaction started
between the two. Lorentz’proof had also another more dramatic effect: the Swedish
academy in 1908 made the very unusual step to overrule the recommendation of the
Physics Nobel Prize Committee to award the Prize to Planck. A Swedish mathematician
who had been to the Rome conference successfully opposed the proposal. He argued that
no Prize should be awarded to a not yet established theory. So Planck didn’t visit
Stockholm on December 10, but he wasn’t in Berlin either. Instead he happened to stay at
Lorentz’ home since months before a date had been fixed for a talk in Leiden. It would last
ten more years before Planck became a Nobel Prize laureate.
In the twenties Lorentz gave another memorable talk in Italy. It was at the
international physics conference which commemorated the famous Italian physicist Volta
in 1927, hundred years after his death. Volta invented the battery in 1800, thus giving
mankind electrical currents. Lorentz was invited to give the concluding talk, summarizing
the astounding development of physics since Volta. Although the emphasis was on the
20th century physics revolution, Lorentz started with some historical remarks. Volta
became a foreign member of the Holland Society in 1782 - before the battery invention.
Volta visited Haarlem and corresponded intensively with Martinus van Marum, physicist
and secretary of the Holland Society.
At the end of his summary talk one recognizes not only the physicist Lorentz, but
also the chairman of the International Committee on Intellectual Cooperation, predecessor
of UNESCO, part of the League of Nations. One hears the great advocate of international
cooperation, when he says: Every country has brought to this congress its character, its
mentality, its way to consider things. Physics is universal, but the way to cultivate it, is not
identical. This work of an ensemble, as an orchestra, is absolutely indispensable for the
beauty and richness of our results.
The Volta talk was Lorentz’ last great discourse since he suddenly passed away a few
months later. Therefore it could be considered as his scientific testament, presented in
Italy.
In December 1925 a great celebration was organized for Lorentz at the occasion that 50
years earlier he had obtained his PhD – a golden doctorate celebration. One of the actions
was to form a fund to facilitate visits between foreign and Dutch theoretical physicists.
About 2400 people donated to this Lorentz fund, about 1000 from the Netherlands and
about 1400 from 20 foreign countries, the latter donors being mainly physicists. On a small
blank visiting card the contributor could write his or her name. In the archives there are
about 115 cards from Italian donors. One of them is Fermi (Fig. 1). He had been to Leiden
for a few months at the end of 1924 where he met Lorentz and his successor Ehrenfest. In
her book Atoms in the family Laura Fermi mentions this connection.
Fig. 1