The Standardization of Time
- Nuno Margalha
- Jul 6
- 10 min read
Reality is born in our hands. If we have doubts about the existence of something, we stretch out our index finger and touch it. The keyboard on your computer or the glass on your mobile phone are real, they exist. Your fingers can confirm this clearly. We ourselves know that we exist in this world. If you have doubts, there are two ways to confirm it: the first is to pinch your arm, a technique that is widely used. You can also, at this very moment, ask the person closest to you if it exists. Let's wait. Was the answer affirmative? Then it must be true that it exists. Was it negative? Confirm that the person next to you really exists, stretch out your index finger and touch them. Does it exist? The conclusion of the experiment is up to you. Our hands seem, in this way, to be the cradle of reality. Is that really the case?
Everything we do, we do in our own world; we cannot reach out and touch other worlds or even step on them. Perhaps this is why it is so difficult to believe in the existence of worlds beyond our own. According to one of the few theories that attempt to enlighten us on this subject, there are other worlds in which we ourselves also exist. Physicists, at the height of their creativity, have christened this theory the “Many-Worlds Interpretation”. The author of the idea is Hugh Everett III. At the age of 12, Hugh Everett III sent a letter to Albert Einstein to clarify a question about what would happen if an unstoppable force acted on an immobile object. The answer was as follows:
«Dear Hugh: There is no such thing as an irresistible force and an immovable body. But there seems to be a very stubborn young man who has fought his way victoriously through strange difficulties of his own making. Yours sincerely, A. Einstein»
Perhaps it was this answer from the greatest genius in physics that motivated him to pursue a career in physics, perhaps it was his mother's stories, or perhaps it was his studies of his father's rifle bullets. We don't know. What we do know is that Hugh Everett III was himself a genius in several areas and created one of the most interesting solutions to enlighten us about the workings of quantum mechanics. His Many Worlds Interpretation is currently accepted in physics as one of the main theories of quantum mechanics, but it was not always this way.
THE COPENHAGEN INTERPRETATION
In 1912, a Belgian businessman, Ernest Solvay, established the Solvay Conferences (1), which were held every three years. The fifth conference, which took place in October 1927, on electrons and photons, was one of the most important of all time. It was attended by 29 scientists, 17 of whom had won or would go on to win the Nobel Prize. Among them were well-known names such as Albert Einstein, Niels Bohr, Max Planck and Erwin Schrödinger. At this conference, the newly formulated quantum theory was discussed, especially in a famous debate between Einstein and Bohr about the behaviour of the electron. The famous “Copenhagen Interpretation” emerged from this conference. To understand it, we first need to know about Schrödinger’s discovery two years earlier, in 1925.
Schrödinger demonstrated, through his equation, that although in a macroscopic view of the world Newton's second law ( F = m a ) obtained good results, at the quantum level this did not happen.
The Schrödinger equation then allows us to calculate the energy of the electron orbitals, and demonstrates that it is not possible to predict the exact position of an electron. This impossibility is due to the fact that electrons are in superpositions, that is, in several positions at the same time. If they are in several positions at the same time, it can be said that they do not behave like particles, but rather like waves. However, when we observe an electron, we see it as if it were a particle. The Copenhagen Interpretation then argues that an electron behaves like a wave, but when it is observed, its wave function collapses and it becomes a particle. This was precisely Bohr's idea, with which Einstein disagreed. It is said that, following this debate, Einstein uttered his famous phrase:
«God does not play dice»
Referring to the fact that the solution presented by Bohr, to explain the transition between wave and particle, is based on probability, and is also dependent on an observer. Bohr's answer was simple:
«Einstein, stop telling God what to do».
After years of seeing the world through the eyes of Newton's classical physics, these geniuses were faced with a reality that was impossible to confirm. The author of the equation that gave rise to this whole controversy, Schrödinger, himself thought that the idea of the collapse of the wave function was nonsense. To the point of suggesting one of the most witty experiments in physics, known today as Schrödinger's Cat experiment.
SCHRÖDINGER'S CAT
The Schrödinger's Cat experiment seeks to exemplify the nonsensical application of the Copenhagen Interpretation to common, everyday objects. It consists, simply, of placing a cat in a box with a vial of cyanide, a radioactive compound, and a radiation meter. According to quantum physics, the atoms of the radioactive substance may or may not decay during the period of the experiment. If the particles of the radioactive substance decay and therefore release radiation, the vial with the poison will be broken and the cat will die. If the particles do not decay, the cat will live. According to the Copenhagen Interpretation, until the box is opened, the cat is simultaneously alive and dead. Upon opening the box, however, the observer will see only a live cat or a dead cat. Although this is not an easy theory to accept, as Einstein pointed out, to this day it has been widely accepted.
THE INTERPRETATION OF THE MANY WORLDS
Thirty years after the fifth Solvay Conference, Hugh Everett defended his doctoral thesis, in which he heroically suggested a solution to the then world-renowned Bohr problem. After defending his doctorate, Everett's thesis advisor managed to convince Bohr to meet with him. However, according to Everett's wife, Bohr would not even discuss the subject, nor would he meet with him.
Everett's proposal was quite simple, he suggested that we simply use Schrödinger's equation to explain the behavior of electrons, nothing more so than that. The next idea, however, was a little more daring.
Faced with the problem of measuring the position of an electron, Everett suggested that the simple observation of an electron would create a new world, where the same electron would appear as a particle.
This world would be different from the previous world, in which the particle still behaved like a wave. Everett's proposal was given the imaginative name of the Many-Worlds Theory. According to the Many-Worlds Interpretation, Schrödinger's cat, the observer, and the entire world are in a superposition, which is obviously more coherent. This is why the existence of several worlds must naturally be considered. To this day, the Many-Worlds Interpretation is one of the few theories that provide a solution to the problem of measuring the position of electrons in quantum physics. It is acknowledged not only by science fiction enthusiasts, but also by renowned physicists such as Sean Caroll.
HANDS AND REALITY
The idea of our presence in several worlds simultaneously is disconcerting. The vastness of the unknown that quantum physics has revealed is frightening. We have been left without understanding what reality itself is. All we can do is consider that it is only in our thoughts that reality is born, lives and dies. After all, it is in the thoughts of our parents that we begin to exist, even before we are born. We do not become reality when someone touches us. Our hands do not make real the world that our feet tread on. It is not possible to touch reality, much less make real what we touch.
We now know that reality is slipping through our fingers and that it suffers from existential problems. And since last weekend, we have discovered that time suffers from similar problems . As for reality, there is little we can do. As for time, since IPR is a School of Watchmaking, we have at least the obligation to try to clarify it — even if, as absurd as it may seem, it is considered that it does not exist.
WHAT IS TIME
In the world of watchmaking, time is not just a philosophical abstraction or a sentimental value: it is a physical unit that must be measured accurately. The history of time standardization has a remarkable history, with the General Conference on Weights and Measures (CGPM) standing out – the international forum responsible for the official definition of the fundamental units of the International System (SI), including the second.
The Metre Convention: the genesis of standardization
On 20 May 1875, twenty nations — including Portugal — signed the Metre Convention in Paris . This international treaty laid the foundations for a worldwide standardisation of units of measurement, which gave rise to the Bureau International des Poids et Mesures (BIPM) , headquartered in Sèvres, on the outskirts of Paris.
Initially focused on defining the metre and the kilogram, the BIPM's work was extended to other physical quantities, including time. The coordination of these activities was then undertaken by the General Conference on Weights and Measures , which has met regularly since 1889 to approve definitions, review standards and ensure the coherence of the international system of units.
The astronomical second: an unstable definition
For centuries, time was measured by astronomical observations.
The second was defined as 1 ⁄ 86400 part of the mean solar day—that is, the twenty-fourth part of one rotation of the Earth divided by 3600.
However, it has been found that the Earth's rotation is not constant. It undergoes small, unpredictable variations of geological, atmospheric and gravitational origin.
This instability became unacceptable for applications requiring extreme precision, such as satellite navigation, synchronization of telecommunications networks or scientific clockmaking. It was necessary to find an invariant reference, present throughout nature.
The atomic second: the revolution of accuracy
The answer came through spectroscopy and quantum physics. Atoms, when moving between energy levels, emit radiation with a specific frequency. In the case of cesium-133, this frequency is remarkably stable.
In 1967, the 13th General Conference on Weights and Measures approved a new definition of the second:
"The second is the duration of 9,192,631,770 periods of the radiation corresponding to the transition between two hyperfine levels of the ground state of the cesium-133 atom."
This moment represented a historic milestone. For the first time, the unit of time ceased to depend on the stars and began to depend on an immutable phenomenon of atomic physics. Since then, atomic clocks have become the ultimate standard of precision.
From Paris to the world: clocks to the rhythm of cesium
The CGPM continues to oversee the evolution of SI definitions. In 2019, it redefined the kilogram, ampere, kelvin and mole based on universal constants. The unit of time, however, remains anchored to cesium radiation, although it paves the way for future standards that are even more precise — such as optical lattice clocks.
Optical Network Clocks
In recent years, so-called optical lattice clocks have become the most accurate timekeeping instruments. They differ from caesium atomic clocks in that they use neutral atoms trapped in an optical lattice – a structure of laser light that immobilizes the atoms in fixed positions.
These atoms are excited by optical radiation, with frequencies much higher than the microwaves used in cesium, which allows for unparalleled temporal resolution.
The precision of these systems is such that, according to the most recent data, the accumulated error would be less than one second in 30 billion years.
Although caesium has not yet been officially replaced as the reference in the International System, optical lattice clocks are the main candidates for the future redefinition of the second, and are currently being tested in national metrology laboratories around the world.
Portugal: a country without Standard Time
In Portugal today, it can be said that time does not exist with any more accuracy than in other countries, as after 145 years of serving the country, the Lisbon Astronomical Observatory is no longer the entity that issues Legal Time.
Since 2019, legislative and institutional changes have created a gap in competences, making it impossible to comply with what Decree-Law No. 279/79 provided. Responsibility for issuing official time should be transferred to the Portuguese Quality Institute, but the legislative process remains undefined.
Meanwhile, the country remains without an active broadcasting entity and without a single public clock that officially keeps time.
Portugal, which once had one of the most prestigious observatories in Europe, no longer has its own legal time.
NOTES:
(1) The Solvay Conferences were born from the vision and generosity of Ernest Solvay (1838–1922), a Belgian industrialist and chemist who made his fortune by developing the chemical process for producing sodium carbonate. Convinced that scientific progress required dialogue between the greatest thinkers of his time, in 1911 Solvay founded a series of high-level scientific conferences that brought together the world’s most influential physicists in an environment of free and rigorous debate. His initiative culminated in the famous fifth conference of 1927, devoted to quantum theory, where two conceptions of reality confronted each other: Einstein’s deterministic view and Bohr’s probabilistic interpretation. Ernest Solvay was not just a patron: he was the architect of a space where science had the freedom to question its own foundations. Although these conferences did not define metrological standards, they were crucial for the theoretical construction that supports the way in which time is measured today — namely through the quantum physics that underpins atomic clocks.
References
Books
Kragh, H. (1999). Quantum Generations: A History of Physics in the Twentieth Century. Princeton University Press.
Carroll, S. (2019). Something Deeply Hidden: Quantum Worlds and the Emergence of Spacetime. Duton Books.
Byrne, P. (2010). The Many Worlds of Hugh Everett III. OxfordUniversity Press.
Heisenberg, W. (1958). Physics and Philosophy. Harper.
Quinn, T. J. (2012). From Artefacts to Atoms. OxfordUniversity Press.
Rovelli, C. (2017). The Order of Time. Allen Lane.
Pais, A. (1982). Subtle is the Lord: The Science and the Life of Albert Einstein. OxfordUniversity Press.
Institutional and scientific websites
Artigo muito interessante e acrescento que não fazia ideia de que não existia «hora legal» em Portugal. Ou será que a hora é definida centralmente na UE?