Tag Archives: General Relativity

The Big Bang Revolutionaries

The Big Bang Revolutionaries  : The Untold Story of Three Scientists Who Reenchanted Cosmology

by Jean-Pierre Luminet

Many widely read scientific writers of our day mistakenly attribute the concepts of the expanding universe and the Big Bang to Edwin Hubble and Albert Einstein. Hubble did provide evidence of an expanding universe, but he neither discovered such evidence nor accepted the radical idea that space itself was expanding. As for Einstein, he held out against the idea of an expanding universe for more than a decade, and ceased working in the field as soon as he had to amend his view. The real heroes of the Big Bang revolution are the Russian Alexander Friedmann and Belgian priest Georges Lemaître. That they are virtually unknown to the general public is one thing. That their contribution is underestimated by astrophysicists and cosmologists is another, for the concepts they promulgated are among the most remarkable achievements of twentieth-century science. The Big Bang Revolutionaries amends the record, telling the remarkable story of how these two men, joined by the mischievous George Gamow and in the face of conventional scientific wisdom, offered a compelling view of a singular creation of the universe in what Lemaître termed a “primeval atom.”

Publisher : Discovery Institute Press
Published : April 23, 2024
ISBN : 978-1-63712-040-8
Pages : 254
Retail Price : $18.95

Jean-Pierre Luminet, a French astrophysicist specializing in black holes and cosmology, is emeritus research director at the French National Centre for Scientific Research. He is a member of the Laboratoire d’Astrophysique de Marseille (LAM) and Laboratoire Univers et Théories (LUTH) of the Paris-Meudon Observatory. Luminet has been awarded several prizes. These include the Georges Lemaître Prize (1999) for his work in cosmology, the UNESCO Kalinga Prize (2021), and the Einstein medal for the Popularization of Science (2021). He has published more than twenty science books, eight historical novels, and eight poetry collections. The asteroid 5523 Luminet was named in his honor.

Advance Praise

This excellent and well-illustrated book convincingly puts into a clear focus the key original contributions of Friedmann and Lemaître in the early twentieth-century revolution in our understanding of the large-scale physical universe.

Roger Penrose, Emeritus Rouse Ball Professor of Mathematics at the Mathematical Institute of the University of Oxford, Emeritus Fellow of Wadham College at Oxford, fellow of the Royal Society, and recipient of the Wolf Prize (1988) and the Nobel Prize in Physics (2020)

The author brings together many aspects of thinking about the large-scale nature of our world from the points of view of concepts, theory, observation, and culture. The account starts with Albert Einstein’s thought that a philosophically satisfactory universe has no boundary, a bold conjecture that proved to fit well with Einstein’s new gravity theory and now agrees with the observational evidence. You will find fascinating details of the evolution of ideas, evidence, and the cultural situation between that time and the early steps by which George Gamow’s brilliant intuition took him to the realization that an even better picture of our universe is that it expanded from a hot dense state.

Jim Peebles, the Albert Einstein Professor in Science, emeritus, Princeton University, and recipient of the 2019 Nobel Prize in Physics

It is rare to find an internationally distinguished astrophysicist who is also a searching and meticulous historian. It is rarer still to find such a person who is also a gifted prose stylist. Jean-Pierre Luminet is such a man. The Big Bang Revolutionaries is invaluable reading for anyone fascinated by the history of the big ideas that have shaped and reshaped Western science and civilization, and for anyone who wants a front row seat to witness the all-too-common character of scientific revolution—messy, full of unexpected twists and turns, and not without its casualties. In the present case and as Luminet dramatically shows, the revolution occurred in the face of sustained prejudice from some of the finest minds in physics and astronomy. As for the wider implications of the Big Bang revolution, Luminet leaves those for the reader to contemplate.

Stephen C. Meyer, Director of the Center for Science and Culture and author of Signature in the Cell, named a Book of the Year by the Times (of London) Literary Supplement, Return of the God Hypothesis, and the New York Times bestseller Darwin’s Doubt

The twentieth century represents an exceptional period in the study of the cosmos. But this century will be remembered above all as the one in which physics, for the first time, made it possible to study the universe and its evolution. Jean-Pierre Luminet, an eminent cosmologist, takes the role of historian in this analysis of the emergence of ideas, and pays tribute to the physicists who contributed to this dizzying scientific adventure.

Michael Mayor, Swiss astrophysicist and professor emeritus at the University of Geneva; a recipient of the Viktor Ambartsumian International Prize (2010), the Kyoto Prize (2015), and the Nobel Prize in Physics (2019)

An inspiring overview of the history and physics of our modern view of the universe by the brilliant scientist Jean-Pierre Luminet, who was first to simulate black hole silhouettes. The reader is introduced to the scientific insights that revolutionized the perception of our cosmic roots and future. A fascinating read!

Abraham (Avi) Loeb, Frank B. Baird Jr. Professor of Science and Director of the Institute for Theory & Computation, Harvard University, and director for the Breakthrough Initiatives of the Breakthrough Prize Foundation

This book is a very careful discussion of the work of three less-known key figures who laid the foundations of modern cosmology—Alexander Friedmann, Georges Lemaître, and George Gamow. It does a great service in detailing the contributions that each of them made to the topic. I particularly appreciate the discussion of the pioneering work and personality of Lemaître, who can justly be called the father of scientific cosmology. With its discussion also of cosmic topology, the book is a unique contribution to the history of cosmology.

George Ellis, emeritus distinguished professor, University of Cape Town, co-author with Stephen Hawking of The Large Scale Structure of Space-Time, former president of the International Society on General Relativity and Gravitation, fellow of the Royal Society, recipient of the Templeton Prize and the Georges Lemaître International Prize

The Big Bang Revolutionaries is one terrific book. And one, I might add, of historical importance inasmuch as it restores to their rightful place two fascinating figures whom the standard history of physics in the twentieth century has shamefully neglected. Lucid? Of course it is lucid. Luminet is a fine astrophysicist. Moving? Very much so, not only for what it says about Friedmann and Lemaître, but for what it reveals about the author’s sensitive intelligence on encountering the story of men whose position of prominence was denied them. It is, all in all, a splendid restoration—something very French, I might add, in that it describes men who should have been monarchs reacquiring their thrones.

David Berlinski, Senior Fellow of the Center for Science and Culture, and author of A Tour of the Calculus, The Advent of the Algorithm, Newton’s Gift, The Devil’s Delusion: Atheism and Its Scientific Pretensions, and Science After Babel

Finally a book that brings the credit of the great cosmological revolution of the twentieth century to where it is properly due: the Russian Alexander Friedmann and the Belgian priest Georges Lemaître.

Carlo Rovelli, founder of the quantum gravity group of the Centre de Physique Théorique (CPT), Aix-Marseille University, and author of the bestselling Seven Brief Lessons on Physics

Big Bang theory has become a popular topic, but who knows the scientists who first proposed the outrageous concept that our entire universe started as an ultra-dense fireball? Theoretical physicist Jean-Pierre Luminet, well-known for his pioneering work on the visualization of black holes, takes the reader through a pedagogical, and historically accurate, tour of the conceptual vistas opened by the inventors of Big Bang theory, namely: the Russian mathematician (and meteorologist) Alexander Friedmann, the Belgian cosmologist (and priest) Georges Lemaître, and, last but not least, the eclectic genius physicist George Gamow. A must-read for any person eager to understand one of the major scientific breakthroughs of twentieth-century physics.

Thibault Damour, Institut des Hautes Études Scientifiques, recipient of the Einstein medal, the Galileo Galilei medal, and the Balzan prize

A brief history of space (4/4)

Sequel of the preceding post A Brief History of Space (3/4) : From Descartes to Schwarzschild

Cosmology developed rapidly after the completion of general relativity by Albert Einstein, in 1915. In this theory, the Universe does not reduce to a space and a time which are absolute and separate; it is made up of the union of space and time into a four dimensional geometry, which is curved by the presence of matter.

Albert Einstein (here in 1910) developed the theory of relativity and was awarded the 1921 Nobel prize for physics. Image by © Hulton-Deutsch, Collection/CORBIS

It is in fact the curvature of space-time as a whole which allows one to correctly model gravity, and not only the curvature of space, such as Clifford had hoped. The non-Euclidean character of the Universe appeared from then on not as a strangeness, but on the contrary as a physical necessity for taking account of gravitational effects. The curvature is connected to the density of matter. In 1917, Einstein presented the first relativistic model for the universe. Like Riemann, he wanted a closed universe (one whose volume and circumference were perfectly finite and measurable) without a boundary; he also chose the hypersphere to model the spatial part of the Universe.

Einstein static universe in a space-time diagram.

At any rate, Einstein’s model made the hypothesis of a static Universe, with the radius of the hypersphere remaining invariable over the course of time. In truth, the cosmological solutions of relativity allow complete freedom for one to imagine a space which expands or contracts over the course of time: this was demonstrated by the Russian theorist Alexander Friedmann, between 1922 and 1924.

At the same time, the installment of the large telescope at Mount Wilson, in the United States, allowed for a radical change in the cosmic landscape. In 1924, the observations of Edwin Hubble proved that the nebula NGC 6822 was situated far beyond our galaxy. Very rapidly, Hubble and his collaborators showed that this was the case for all of the spiral nebulae, including our famous neighbor, the Andromeda nebula: these are galaxies in their own right, and the Universe is made up of the ensemble of these galaxies. The “island-universes” already envisaged by Thomas Wright, Kant and Johann Heinrich Lambert were legitimized by experiment, and the physical Universe seemed suddenly to be immensely enlarged, passing from a few thousand to several dozen million light-years at the minimum. Beyond this spatial enlargement, the second major discovery concerned the time evolution of the Universe. In 1925, indications accumulated which tended to lead one to believe that other galaxies were systematically moving away from ours, with speeds which were proportional to their distance. Continue reading

The Warped Science of Interstellar (4/6) : Time dilation and Penrose process

Sequel of the preceding post The Warped Science of Interstellar (3/6)

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 fourth 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.

A HUGE TIME DILATION

The elasticity of time is a major consequence of relativity theory, according to which time runs differently for two observers with a relative acceleration – or, from the Equivalence Principle, moving in gravitational fields of different intensities. This well-known phenomenon, checked experimentally to high accuracy, is called « time dilation ».

The celebrated "smooth watches" by Salvador Dali are a nice metaphor of time elasticity predicted by Einstein's relativity theory.
The celebrated “smooth watches” by Salvador Dali are a nice metaphor of time elasticity predicted by Einstein’s relativity theory.

Thus, close to the event horizon of a black hole, where the gravitational field is huge, time dilation is also huge, because the clocks will be strongly slowed down compared to farther clocks. This is one of the most stunning elements of the scenario of Interstellar : on the water planet so close to Gargantua, it is claimed that 1 hour in the planet’s reference frame corresponds to 7 years in an observer’s reference frame far from the black hole (for instance on Earth). This corresponds to a time dilation factor of 60,000. Although the time dilation tends to infinity when a clock tends to the event horizon (this is precisely why no signal can leave it to reach any external observer), at first sight a time dilation as large as 60,000 seems impossible for a planet orbiting the black hole on a stable orbit.

As explained by Thorne in his popular book, such a large time dilation was a « non-negotiable » request of the film director, for the needs of the story. Intuitively, even an expert in general relativity would estimate impossible to reconcile an enormous time differential with a planet skimming up the event horizon and safely enduring the correspondingly enormous gravitational forces. However Thorne did a few hours of calculations and came to the conclusion that in fact it was marginally possible (although very unlikely). The key point is the black hole’s spin. A rotating black hole, described by the Kerr metric, behaves rather differently from a static one, described by the Schwarzschild metric. The time dilation equation derived from the Kerr metric takes the form:

1 – (dτ/dt)2 = 2GMr/c2rho2, where rho2 = r2 + (J/Mc)2cos2θ.

Continue reading

My books (1) : Black holes

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…), only 4 of my essays have been translated in English.

The first one was :

Black Holes

312 pages – Cambridge University Press, 1992 – ISBN 0 521 40029 5 (hardback) – ISBN 0 521 40906 3 (paperback) – Foreword by Joseph Silk.

black-holesBlack holes are the most fascinating discovery of modern astronomy. They have already become legendary, and form the basis of many myths and fantasies. Are they really the monsters of science fiction which devour light and stars? Are they purely hypothetical objects from the theory of relativity or are they an observable reality?
In answering these questions, the author takes us on a fabulous voyage through space and time. He explains how stars are born, light up and die. He takes us into the strange world of supernovae, X-ray stars and quasars. We travel on a journey to the very edge of the universe and to the limits on contemporary physics.
The amount of information conveyed is impressive. The intended audience is readers with some understanding of physics who are seeking a coherent, accurate nonmathematical overview of black-hole physics and all the astronomical situations that the discipline seems to explain. Also, any student embarking on a serious technical study of general relativity or astrophysics will find the book a first-rate overview of an important part of the story. (…) This is an outstanding work of scientific exposition.” — John Barrow, Nature Continue reading

The Rise of Big Bang Models (2) : Static solutions

Sequel of previous post :  From Myth to Science

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.

The History of Relativistic Cosmology can be divided into 6 periods :

– the initial one (1917-1927), during which the first relativistic universe models were derived in the absence of any cosmological clue.

– a period of development (1927-1945), during which the cosmological redshifts were discovered and interpreted in the framework of dynamical Friedmann-Lemaître solutions, whose geometrical and mathematical aspects were investigated in more details.

– a period of consolidation (1945-1965), during which primordial nucleosynthesis of light elements and fossil radiation were predicted.

– a period of acceptation (1965-1980), during which the big bang theory triumphed over the « rival » steady state theory.

– a period of enlargement (1980-1998), when high energy physics and quantum effects were introduced for describing the early universe.

– the present period of high precision experimental cosmology, where the fundamental cosmological parameters are now measured with a precision of a few %, and new problematics arise (nature of the dark energy, topology of the universe, new cosmologies in quantum gravity theories, etc.)

Let us follow chonologically the rather hectic evolution of the ideas in the field. Continue reading