As Ruínas de um Experimento

O que acontece com a velocidade da luz quando a luz se propaga num meio em movimento?

Por que se dar ao trabalho?

Holanda

=

fundado em 1927

originalmente

Nederlandsch Historisch Natuurwetenschappelijk Museum

preservação da herança científica neerlandesa

As

Ruínas

de um

Experimento

troughs for quartz

o que foi preservado dos experimentos de Zeeman com o efeito Fizeau

Ad Maas

Beto Pimentel

Museum Boerhaave

admaas@museumboerhaave.nl

Universidade Federal do Rio de Janeiro

beto@if.ufrj.br

1914-1918

experimentos de Zeeman com o efeito-Fizeau na água

P. Zeeman, Fresnel's Coefficient for Light of Different Colours, in:

KNAW, Proceedings, 17 I, Amsterdam, 1914, pp. 445-451

P. Zeeman, Fresnel's Coefficient for Light of Different Colours. Second Part, in:

KNAW, Proceedings, 18 I, Amsterdam, 1915, pp. 398-408

P. Zeeman, An Optical Method for Determining the Ratio between the Mean and Maximal Velocities in

the Turbulent Motion of Fluids in a Cylindrical Tube. Contribution to the Experiment of Fizeau, in:

KNAW, Proceedings, 18 II, Amsterdam, 1916, pp. 1240-1247

P. Zeeman, Direct Optical Measurement of the Velocity at the Axis in the Apparatus for Fizeau's Experiment, in:

KNAW, Proceedings, 19 I, Amsterdam, 1917, pp. 125-132

calhas para o quartzo

Zeeman 1914-1918:

Reprodução do experimento de Fizeau de 1851 para testar a correção do termo dispersivo de Lorentz

peças de vidro feitas pela Zeiss em Jena

calhas para o vidro

reprodução do experimento de Fizeau de 1851 sobre o arrasto do éter

o "aparato" de Zeeman em exibição

Einstein: os experimentos de Zeeman preencheram "uma desagradável lacuna ainda existente"

1919-1922

experimentos de Zeeman com o efeito-Fizeau em sólidos

von Laue 1907:

coeficiente de arrasto segue da adição relativística de velocidades

(a) ela não muda

P. Zeeman, The Propagation of Light in Moving Transparent solid substances. I. Apparatus for the

Observation of the Fizeau-effect in Solid Substances, in:

KNAW, Proceedings, 22 I, 1919-1920, Amsterdam, 1919, pp. 462-470

(b) ela é somada à velocidade do meio

A. Snethlage & P. Zeeman, The Propagation of Light in Moving, Transparent, Solid Substances. II.

Measurements on the Fizeau-effect in Quartz, in:

KNAW, Proceedings, 22 II, 1920, Amsterdam, 1920, pp. 512-522

Coeficiente de Fresnel introduzido para explicar o resultado do experimento de Arago com o prisma (SÓLIDO)

(c) apenas uma fração específica da velocidade do meio é adicionada à velocidade da luz

Lorentz introduz um termo dispersivo na expressão do coeficiente de arrasto

P. Zeeman, W. de Groot, A. Snethlage & G. C. Dibbetz. The Propagation of Light in Moving, Transparent, Solid Substances. II 1. Measurements on the Fizeau-Effect in Flint Glass, in:

KNAW, Proceedings, 23, Amsterdam, 1922, pp. 1402-1411

arrasto parcial do éter

porém nunca testado em sólidos em movimento!

razão boa o suficiente?

Nós achamos que não.

aparato de Zeeman para medir o efeito-Fizeau em sólidos!

corroboração do coeficiente de arrasto de Fresnel

Zeeman

interferômetro já montado

Visita de Einstein a Amsterdã em maio de 1920

Einstein

O quê, então?

diversão

Paul Ehrenfest

Zeeman communicated the first results of his solid-medium experiments at a meeting of the Royal Dutch Academy of Sciences on 3 March 1919. He started his exposition by referring to the earlier experiments in moving water: ‘There are many reasons to be adduced for carrying out an experiment, so exceedingly difficult as that of Fizeau, in the first place with water. It is, however,’ Zeeman continues, ‘also interesting to examine the motion of light in SOLID [emphasis in the original], transparent, rapidly moving substances.’ Remarkably, the question why this should be interesting is not answered, neither here, nor anywhere else. This series of experiments, which engaged him and his collaborators for several years and for which a costly apparatus had to be built, was started altogether without a solid (no pun intended) scientific justification. Zeeman loved to plunge into delicate and complicated experimental setups, and sometimes seemed to have lost the sight of the larger, scientific context. This appears to be an exemplary case.

desafio experimental

showing off to visitors

treinamento de estudantes

passa-tempo

vento de éter não podia ser detectado por refração!

1886 Reprodução do experimento de Fizeau de 1851

colaboradores

introduzido para explicar o resultado do experimento de Arago de 1810 com o prisma

W. de Groot

De fato, foi demonstrado por volta de 1870 que nenhum efeito de primeira ordem (v/c) deveria ser mensurável se o coeficiente de Fresnel é válido

1887 "O" experimento de Michelson-Morley

equivalente aos experimentos com telescópios preenchidos com água

G. C. Dibbetz

propostos por Boscovich e outros e finalmente realizado por Airy em 1871

2

Maxwell demonstrou que efeitos de segunda ordem (v /c ) poderiam, em princípio, ser medidos

A. Snethlage

No entanto, o efeito seria incrivelmente pequeno - em torno de um em um milhão

(na verdade uma reprodução do experimento de Michelson de Potsdam em 1881)

Natuurkundig Laboratorium

Michelson + Morley

Zeeman had secured tenure in Amsterdam in 1897, at a time when in the Netherlands the so-called ‘research university’ started to take shape. Before the final years of the nineteenth century, the Dutch universities had been mainly considered as teaching institutes. The laboratories that had been erected for the natural sciences were educational laboratories. Only from the last quarter of the century on, science professors increasingly started to use their laboratory budgets and instruments consistently to build up a research apparatus and to introduce their students into their particular, specialized fields of research. After this generation of science professors had proved to be remarkably successful – the last decades of the nineteenth century saw the rise of the so-called ‘Second Golden Age’ of Dutch science – research started to become institutionalized at the universities. Administrators became aware that fundamental research appeared to be something worthwhile to be supported for its own right and increasingly appreciated the research activities of their science professors.

Amsterdam physics reflects this development in a telling manner. The history of Amsterdam physics started with the foundation of the University of Amsterdam in 1877. Johannes Diderik van der Waals (Nobel Prize 1910) – one of the pioneers of the Second Golden Age – was the first, and for the years to come only physics professor. Thanks to his (international) scientific reputation, however, he gradually managed to realize an expansion of staff and funding. When he retired in 1908 he left Amsterdam physics with four professors and a relatively well-endowed (though old-fashioned) laboratory. One of the three professors was Johannes Diderik van der Waals Jr. who occupied a chair in theoretical physics. Remmelt Sissingh took the heaviest teaching duties, Philips Kohstamm became extraordinary professor in applied thermodynamics and Pieter Zeeman would in practice grow into the first researcher "pur sang" in Amsterdam physics. Thanks to his international reputation, after his shared Nobel Prize with Lorentz in 1902, he was able to realize ever better research conditions and only modest teaching duties.

The pinnacle of Zeeman’s efforts to improve his research conditions was the foundation of his own laboratory Physica. Whereas the old laboratory, the Natuurkundig Laboratorium (which opened its doors in 1882), was a classic educational laboratory with a large auditorium and several rooms to study different natural phenomena, Physica was an excellently equipped research laboratory, specialized in magneto-optical research. Only advanced students were allowed to enter its doors. Physica can be considered a milestone in the history of the Dutch research university, as a materialization of this modern type of university in which next to teaching, research is of equal importance.

Physica was promised to Zeeman in 1917, and finished in 1923 – the difficult circumstances created by the First World War caused some delay. Zeeman conducted his Fizeau-experiments while waiting for the (postponed) lab. The old laboratory was in a bad state: it was overcrowded with students and suffered heavily from vibrations which made the continuation of his delicate magneto-optical researches impossible. In any case, even though the Fizeau series might not have been the research of Zeeman’s first choice, he pursued it with dedication. Even before Physica opened its doors, many efforts were spent on research.

Teaching did not really have Zeeman´s interest. He typically gave a course for advanced students for one hour a week. Often he addressed topics that coincided with his research. The reserved Zeeman did not entertain close relationships with his students, though he took his educational duties seriously.

período de transição

Michelson 1881

laboratório "old-style": auditório rodeado de laboratórios de demonstração

van der Waals

aposentado 1908

van der Waals Jr.

Sissingh

experimento de Potsdam

Kohstamm

Zeeman

pesquisador "puro-sangue"

mas e o arrasto parcial "confirmado" por Fizeau?

Novo laboratório de Zeeman:

"Physica"

laboratório de pesquisa moderno

The first decades of the 20th century saw the institutionalization of the Dutch research university. Basically, this type of university was the result of an ‘unspoken’ agreement between society and the science professor. The latter was relatively well endowed to pursue his research without having to bear any responsibility. In return his research was expected to further the (international) prestige of land, city and university by unraveling the mysteries of nature, life and universe. Unfortunately, professors could be distracted by their own, particular inclinations. That Zeeman managed to measure the speed of light in to-and-fro moving transparent rods with high velocity in an accurate manner, was a remarkable achievement. Yet, it did not address major scientific questions (it did not even aim to), and it did not increase the reputation of Amsterdam physics considerably. Indeed, from this point of view Zeeman’s moving solid-series can be considered as the first misinvestment in Dutch experimental physics. By the time Zeeman became engaged with it, the only physics research laboratory in the Netherlands was the famous cryogenic laboratory of Kamerlingh Onnes, who had, after many years of building up, step by step, his apparatus, liquefied helium for the first time in 1908, and had three years later discovered superconductivity. However, also his lab would start making wrong choices, would lose the large scientific context out of sight and, despite increasing research budgets, would lose its position as the world’s most cutting-edge cryogenic laboratory. However, it would take a number of decades before Dutch society started to demand more insight in research activities and founded research councils and other annoying measurements to check these. Zeeman’s moving solid-series did not produce important scientific results, but exactly because of this it revealed at an early stage the shadow-side of the unrestrained research university. And this is the real historical significance of Zeeman’s moving solid experiments.

prometido para 1917

entregue em 1923

retomada das pesquisas de Zeeman sobre a influência de fenômenos magnéticos na luz

larga o efeito-Fizeau quase instantaneamente

mal-gerenciamento

inclinações pessoais

mais burocracia para prevenir mais mal-gerenciamento

laboratório criogênico de Kamerlingh Onnes também!