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The Warped Science of Interstellar (6/6) : the final equation

Sequel of the preceding post The Warped Science of Interstellar (5/6)

In november  2014, the Hollywood blockbuster and science-fiction movie Interstellar was released on screens and  much mediatic excitation arose about it.
This is the last one of a series of 6 posts devoted to the analysis of some of the scientific aspects of the film, adapted from a paper I published last spring in Inference : International Review of Science.


The final equation

At the very end of the film, the scientist’s character called Murph begins to write an equation aimed to solve the problem of the incompatibility between general relativity and quantum mechanics. We can see blackboards covered by diagrams and equations supposed to be a possible way to the « ultimate equation » of a so-called « Theory Of Everything ». If discovered by the scientists, it would eventually help to solve all the problems of humanity. I will not discuss the naivety of such a view, but briefly discuss the question whether the equations on the screen have any meaning.

The complete unification of the four fundamental interactions can be achieved only at very high energy, conditions which prevailed in the very early universe during the so-called « Planck era ».
The complete unification of the four fundamental interactions can be achieved only at very high energy, conditions which prevailed in the very early universe during the so-called « Planck era ».

At first sight we can doubt because the unification of general relativity and quantum mechanics remains unsolved – even if various approaches, such as the loop quantum gravity[1], the string theory[2] (of which the Randall-Sundrum model referred above is a very particular solution) or the non-commutative geometry[3], are intensively explored by theoretical physicists all around the world. Continue reading

My books (2) : Glorious Eclipses

Until now I published as an author 30 books in my native language (French), including 14 science essays, 7 historical novels  and 9 poetry collections (for the interested reader, visit my French blog  here.
Although my various books have been translated in 14 languages (including Chinese, Korean, Bengali…), 4 of my essays have been translated in English.

The second one was :

Glorious Eclipses : Their Past, Their Present, Their Future

Translated from French by Storm Dunlop
Cambridge University Press, 2001 -ISBN 0 521 79148 0

GEclipsesThis beautiful volume deals with eclipses of all kinds – lunar, solar and even those elsewhere in the Solar System and beyond. Bringing together in one place all aspects of eclipses, it is written by the perfect team : Serge Brunier is a life-long chaser of eclipses, and internationally-known astronomy writer and photographer, whilst Jean-Pierre Luminet is a famous astrophysicist with a special interest in astronomical history. Lavishly illustrated throughout, Glorious Eclipses covers the history of eclipses from ancient times, the celestial mechanics involved, their observation and scientific interest. Personal accounts are given of recent eclipses – up to and including the last total solar eclipse of the 20th century : the one on August 11th 1999 that passed across Europe, Romania, Turkey and India. This unique book contains the best photographs taken all along its path and is the perfect souvenir for all those who tried or wished to see it. In addition, it contains all you need to know about forthcoming eclipses up to 2060, complete with NASA maps and data.




Why should a theoretical astrophysicist, who has rarely peered through the eyepiece of a telescope, preferring to speculate on the invisible architecture of space-time by means of dry equations, be interested in eclipses, to the extent of writing a book about them?

It is true that Einstein’s general theory of relativity, which has been a constant intellectual delight for me over so many years, was first proved experimentally thanks to a ‘simple’ solar eclipse. That was on 29 May 1919. But such an argument satisfies only the intellect. When it comes to the soul, it demands a greater spectacle, a more tangible emotion.

I was not yet ten on 15 February 1961, when a total eclipse of the Sun crossed the Provence where I was born. All I can recall is preparing smoked glass under the watchful eye of our schoolmistress. Clouds over Cavaillon probably spoilt the spectacle, because I have no memory of the eclipse itself…

Then… then I waited nearly forty years before finally seeing a total eclipse of the Sun. That was on 26 February 1998, in the Sierra Nevada de Santa Maria, in the north of Colombia. Serge Brunier and a few other colleagues, genuine eclipse chasers, had finally convinced me that any astrophysicist worthy of the name should not ‘die a fool’! It is true that, obviously, such a recurrent and ‘nearby’ astronomical event might seem somewhat prosaic to someone who spends his life in abstract research on models of the Big Bang, black holes, and the realms of space-time.

On that day, however, between 10:59 and 11:03, I experienced what John Couch Adams described so well, some 150 years before. The English mathematician-astronomer, less accustomed to handle telescopes than complex equations of celestial mechanics – he predicted the existence of the planet Neptune through calculation – witnessed a total eclipse of the Sun for the very first time in his career during the summer of 1846. He subsequently described the extraordinary emotions he felt as an astronomer – and, moreover, an experienced one – who realized that he was a novice when he discovered this astounding cosmic drama for the very first time.

The darkness that descends suddenly in the very middle of the brilliance of the day; this new light that arises from the obscurity; the planets aligned like a necklace of pearls in a configuration that is never seen by night; and the Sun’s flamboyant corona…

These few minutes in which time seems suspended, create the almost palpable feeling of being, transiently, part of the invisible harmony that rules the universe. It is as if a sudden opening in the opaque veil of space allows our inner vision to reach into the otherwise hidden depths of the cosmos, giving us humans – mere insignificant specks of dust – an all-too-brief instant to see the other side of the picture.

To me, the invisible is not restricted to dark objects that our telescopes cannot detect. It is also, and in particular, the secret architecture of the universe, the insubstantial framework of our theoretical constructs. I have always been moved by black. Not black as in absence, but rather black as revealing light. According to the painter Francois Jacqmin ‘Shadow is an insatiable star-studded watchfulness. It is the black diamond that the soul perceives when the infinite rises to the surface.’ Astrophysics and cosmology team with examples where black is all-important. It is in the black of the night that one sees stars, or, in other words, that one perceives the immensity of the cosmos. This same night-time darkness reveals the whole evolution of the cosmos, and the finite nature of time. The mass of the universe is largely dominated by dark matter; massive, non-luminous objects, which through their gravitational attraction govern the dynamics of the cosmos. As for black holes, the epitome of invisibility, they are perhaps secret doorways opening onto other regions of space-time.

Another aspect of eclipses enthrals me: their historical and cultural dimension. I have always been attracted by the way in which different forms of human invention interact. Science, despite being an effective and rational approach to truth, nevertheless remains incomplete. Art, philosophy, and the comparative study of traditions, myths and religions, are all complementary approaches that are indispensable for anyone who wants to gain a greater insight into where they fit in the cosmic scheme of things.

In unfolding the story of people, their civilizations, and their relationships with heavenly phenomena, one cannot but be fascinated to see how past eclipses have influenced their course. The impression of a supernatural power engendered by the sudden disappearance of the Sun or the Moon has often struck human beings, frightened by an apparently hostile and incomprehensible nature, to the extent of changing their behaviour.

That’s enough. My colleague, Serge Brunier, and I decided to write a book that alternated between these ‘two voices’. After all, the various types of eclipses are created by the Earth and the Moon taking it in turn to pass in front of each other beneath the blazing Sun…

Eclipses are a benign contagious virus, which once it has infected you, recurs at intervals. Which is why, for the eclipse of 11 August 1999, I went deep into the Iranian desert, to be (almost) certain of finding a sky devoid of clouds.



An extrordinarily beautiful book, Glorious Eclipses guides us elegantly through the history of obscurations of the sun and moon – from the ancient Chinese belief that a dragon was devouring the daytime star through current theories and on to celestial events forthcoming in the next six decades. Some of the most startling images come from the days when photography was in its infancy and astronomers still made drawings of eclipses.

Scientific American, June 2001

Darkness at noon

At first sight, this is the ultimate eclipse book. Oversize, well-produced photographs in a large-format book are accompanied by interesting text covering a wide variety of eclipses phenomena. The partnership of an astronomer writer/editor and a professional astronomer, albeit a cosmologist, successfully brings the beauty of total solar eclipses to the fore.

Although the writers alternate, the difference is not jarring, perhaps thanks to the expert translator, Storm Dunlop. In a chapter entitled “The great cosmic clockwork”, Serge Brunier, long-time editor of the French popular astronomy journal Ciel et Espace, discusses the many kinds of eclipses and occultations (when one astronomical body occults, or hides, another). He even includes the eagerly awaited 2004 transit of Venus – the passage of Venus across the face of the Sun. This will be the first transit of Venus visibe from Earth since 1882.

The reproduction of photographs in 25 cm x 35 cm format on heavy stock is outstanding. For example, we see Saturn’s rings extending across a double page for almost half a metre in a Hubble Space Telescope image. The authors justify using this image, which shows the shadow of Saturn’s satellite Titan on Saturn’s clouds, by pointing out that it corresponds to an eclipse of the Sun by Titan as seen from Saturn. It’s a pity, though, that Brunier calls himself an “eclipse chaser” – that common but misleading phrase seemps to imply that people can outrun, or even outfly, eclipses, which has never been done.

Brunier is responsible for some of the most magnificent photographs, such as one from the 1991 total solar eclipse visible from the Mauna Kea Observatory in Hawaii, with a few telescopes in the foreground. But the image I found most arresting is not one of this; it is a wide-angle shot of the 1991 eclipse viewed through a hole in the clouds and showing the front of Reims Cathedral in the left foreground.

In his chapters on the history and cultural significance of eclipses, Jean-Pierre Luminet reproduces a remarkable set of historical images related to solar and lunar eclipses from around the world. These are no doubt related to his work on an exhibition of astronomical atlases held in Paris at the Bibliothèque Nationale in 1998.

It was good to read about myths that cast eclipses in a favourable light rather than as evil omens. Luminet also describes the history of scientific discovery through observations of solar eclipses. One example is the discovery at the 1868 total solar eclipse of the spectrum of the solar chomosphere – the layer of the Sun just above the surface that becomes briefly visible at the beginning and end of totality. The element helium was also discovered at this eclipse.

There is much that is excellent in the book. The charts of future eclipses at the end of the book are redrawn at the highest quality. Lunar eclipses are included in the text, photos and charts, looking almost as dramatic on the page as the solar ecipses, even though they are much less so in reality. As a book of history, myth, literature, photography and expeditionary experiences, Glorious Eclipses is outstanding, despite its omission of the solar research carried out at recent eclipses.

Jay Pasachoff, Nature, vol. 410, 29 march 2001.

Wonder of day turned into light

A total eclipse of the Sun is about as astonishing a treat as nature provides. For a few minutes, the Moon exactly covers the Sun, making night from day and displaying the otherwise invisible solar atmosphere. This book celebrates eclipses of both Sun and Moon (the rather less spectacular sweeping of Earth’s shadow across the lunar surface) from many directions, including the complex history of eclipse observations and their declining but still real scientific value.

Serge Brunier and Jean-Pierre Luminet are respectively a science journalist and photographer, and a senior astronomer. This book, well translated from French by Storm Dunlop, makes the most of their strengths. It displays a deep understanding of history, some gripping science and a wealth of images, both of eclipses and of the many ways in which they have been represented over the years.


If you want to take up eclipse chasing, the book’s maps of future eclipses will tell you when and where to be, and its illstrations will tell you what to expect and how to observe in safety. There are explanations of the eclipse cycle, or Saros, and of the fact that in the far future, there will be no more solar elipses as the Moon’s distance from the Earth increases.

The book also provides generous coverage of lunar eclipses and of related events such as occultations and transits. There is even space to reveal how planets in other solar systems are being detected as they eclipse their own star as seen from Earth. Eclipses still make cutting-edge science thousands of years after they first caused dismay to our ancestors.

Martin Ince, Deputy Editor, The Times Higher, March 9 2001.

Not in the shade

This attractive and beautifully illustrated book, by two Paris astronomers and dedicated eclipse-chasers, was originally published in French under the title Eclipses, Les Rendez-vous Celestes (Larousse-Bordas/HER, 1999). The present English translation is by Storm Dunlop. This book is a veritable mine of information on eclipses and is suitable for anyone who has an interest in eclipses, be they amateur or professional astronomer, photographer or historian.

The scene is set in the first chapter, which captures much of the appeal of total solar eclipses and leaves the reader in no doubt as to why eclipse chasers will travel vast distances to witness a few minutes of totality.

In chapters two and three, the historical and literary aspects of both solar and lunar eclipses are discussed. Although there is some sound history in the first of these chapters, there is also much speculation – especially with regard to such torical and literary aspects of both such diverse matters as Stonehenge, Thales, and the date of the Crucifixion of Jesus. Regrettably, there are several serious errors. Thus the “Assyrian tablet dating from the

2nd century BC” (p40) is in fact from Babylonia, several centuries after the demise of Assyria. Thucydides reports three eclipses, not just two (p43). “According to the Evangelists,” Jesus was not “crucified on a Thursday,” (p44). Chapter three contains some intriguing literary allusions to eclipses in prose and poetry – both ancient and modern.

Chapters four to seven provide the main substance of this book and are both fascinating and informative. They deal respectively with: the cause of both lunar and solar eclipses; lunar and planetary occultations and also Mercury and Venus transits; total solar eclipse phenomena; and the famous or infamous (depending on the wearher) 1999 eclipse. In particular, it is gond to see a discussion of occultations and transits – which, in a sense, are eclipses in their own right.

The final chapter contains helpful hints for observing and photographing eclipses and also a series of attractive maps showing the visibility of future solar and lunar eclipses – with special emphasis on those over the next 20 years. Unfortunately many of the individual solar eclipse maps (p156–69) are confusing; in each case the maps show “Total eclipse begins at sunrise”, “Path of totality” and “Total eclipse ends at sunset” whether the eclipse was annular or total.

Overall, this is a splendid hook, profusely illustrated.

F Richard Stephenson. Astronomy & Geophysics, 2001 December (Vol.42), 6.33


The Rise of Big Bang Models (5) : from Gamow to Today

Sequel of previous post : Lemaître

In this series of posts about the history of relativistic cosmology, I  provide an epistemological analysis of the developments of the field  from 1917 to 2006, based on the seminal articles by Einstein, de Sitter, Friedmann, Lemaître, Hubble, Gamow and other main historical figures of the field. It appears that most of the ingredients of the present-day standard cosmological model, including the accelation of the expansion due to a repulsive dark energy, the interpretation of the cosmological constant as vacuum energy or the possible non-trivial topology of space, had been anticipated by Lemaître, although his papers remain mostly  unquoted.

First English Edition of The primeval atom
First English Edition of The primeval atom

Lemaître, the "Big bang Man"
Lemaître, the “Big bang Man”
The hot big bang model

By 1950, when Lemaître published a summary, in English, of his theory, entitled The Primeval Atom: An Essay on Cosmogony, it was thoroughly unfashionable. Two years previously the rival theory of a « steady state » universe, supported principally by Thomas Gold in America and by Hermann Bondi and Fred Hoyle in Britain, had met with widespread acclaim. Their argument was that the universe had always been and would always be as it is now, that is was eternal and unchanging. In order to obtain what they wanted, they assumed an infinite Euclidean space, filled with a matter density constant in space and time, and a new « creation field » with negative energy, allowing for particles to appear spontaneously from the void in order to compensate the dilution due to expansion ! Seldom charitable towards his scientific adversaries, Fred Hoyle made fun of Lemaître by calling him « the big bang man ». In fact he used for the first time the expression « big bang » in 1948, during a radio interview.

Thomas Gold, Hermann Bondi and Fred Hoyle, promotors of the steady state theory"
Thomas Gold, Hermann Bondi and Fred Hoyle, promotors of the steady state theory”

The term, isolated from its pejorative context, became part of scientific parlance thanks to a Russian-born American physicist George Gamow, a former student of Alexander Friedmann. Hoyle therefore unwittingly played a major part in popularising a theory he did not believe in; he even brought grist to the mill of big bang theory by helping to resolve the question why the universe contained so many chemical elements. Claiming that all the chemical elements were formed in stellar furnaces, he was contradicted by Gamow and his collaborators Ralph Alpher and Robert Hermann. The latter took advantage of the fact that the early universe should have been very hot. Assuming a primitive mixture of nuclear particles called Ylem, a Hebrew term referring to a primitive substance from which the elements are supposed to have been formed, they were able to explain the genesis of the lightest nuclei (deuterium, helium, and lithium) during the first three minutes of the Universe, at an epoch when the cosmic temperature reached 10 billion degrees. Next they predicted that, at a later epoch, when the Universe had cooled to a few thousand degrees, it suddenly became transparent and allowed light to escape for the first time. Alpher and Hermann calculated that one should today receive an echo of the big bang in the form of « blackbody » radiation at a fossil temperature of about 5 K. Their prediction did not cause any excitement. They refined their calculations several times until 1956, without causing any more interest; no specific attempt at detection was undertaken. Continue reading

Luminet’s Illuminations

Luminet’s reinstated visualization of a finite Universe, albeit one from which we can exit through one face and simultaneously enter through the opposite one, relies upon a keplerian form of mental sculpture that may be described as plastic rather than algebraic. Luminet’s characteristic lithograph, Big Bang, exploits the spatial vocabulary of perspective to evoke realms beyond the three dimensional. Whereas Escher relied on contradictions and oscillating ambiguity in his graphic art, Luminet suggests plunging, interpenetrating and matter organizes itself into structures on the right; the tumbling dice on the left imply irreversible disorganization arising from chance. The remarkable range of Luminet’s creativity in art and science is integral to his agenda to recreate what he calls a « humanism of knowledge » — not that the arts and sciences are somehow to be conflated, because they work in very different ways, with illogical and logical means. But Luminet argues that they well up from the same instincts and intuitions: « I do not believe that we acquire at the beginning the ‘heart of an artist’ or the ‘heart of a scientist’. There is simply within oneself a single devouring curiosity about the world. This curiosity pushes us to explore it through various languages and modes of expression, » he says.

Martin Kemp, professor of the history of art at the University of Oxford. Excerpt from “Luminet’s Illuminations : Cosmological Modelling and the Art of Intuition”, Nature, 20 november 2003, vol. 426, p. 232