Washington Post highlights historic clash between Einstein and Bergson on the nature of time

2015_Einstein_bannerWith the 100th anniversary of the general theory of relativity coming up in November, Einstein is popping up everywhere. Yesterday’s Washington Post ran a terrific feature on Einstein books, including three of our own: Hanoch Gutfreund and Jürgen Renn’s The Road to Relativity, Einstein’s Relativity: The Special and the General Theory, and Jimena Canales’s The Physicist and the Philosopher.

One of the most fascinating chapters of Einstein’s public life revolves around an encounter he had with Henri Bergson, the renowned philosopher, on April 6, 1922, in Paris. It was on this day that Einstein and Bergson publicly debated the nature of time, touching off a clash of worldviews between science and the humanities that persists today. The philosopher Bergson argued that time was not merely mechanical, and should be seen in terms of lived experience; Einstein dismissed Bergson’s psychological notions as irreconcilable with the realities of physics. The Physicist and the Philosopher tells the remarkable story of how this explosive debate between two famous thinkers created intellectual rifts and revolutionized an entire generation’s understanding of time.

Nancy Szokan’s piece in Washington Post recounts the dramatic collision:

In The Physicist and the Philosopher, Canales recounts how Bergson challenged Einstein’s theories, arguing that time is not a fourth dimension definable by scientists but a ‘vital impulse,’ the source of creativity. It was an incendiary topic at the time, and it shaped a split between science and humanities that persisted for decades—though Einstein was generally seen as the winner and Bergson is all but forgotten.

Bergson and Einstein, toward the end of their lives, each reflected on his rival’s legacy and dedication to the pursuit of truth: Bergson during the Nazi occupation of Paris and Einstein in the wake of the first hydrogen bomb. Referencing Einstein’s quest for scientific truth, Hanoch Gutfreund recently had an article in the Huffington Post on how Einstein helped shape the Hebrew University of Jerusalem (home of the Albert Einstein Archives online):

On the occasion of the opening of the university, Albert Einstein published a manifesto “The Mission of our University”, which generated interest and excitement in the entire Jewish and academic worlds.

It states: “The opening of our Hebrew University on Mount Scopus, at Jerusalem, is an event which should not only fill us with just pride, but should also inspire us to serious reflection. … A University is a place where the universality of human spirit manifests itself. Science and investigation recognize as their aim the truth only.”

Read the rest here.

November’s big anniversary serves as a reminder of the enduring commitment to scientific investigation that continues at The Hebrew University and centers of learning all over the world today.

Read sample chapters of The Physicist and the Philosopher here, The Road to Relativity here, and Relativity here.

You can find information on the Digital Einstein Papers, an open access site for The Collected Papers of Albert Einstein, comprising more than 30,000 unique documents here.

Win a copy of THE ROAD TO RELATIVITY over on the official Einstein Facebook page!

Head on over to the official Facebook page of Albert Einstein to enter to win a copy of The Road to Relativity.

The contest starts today and will run from July 22nd at 11 AM ET until Wednesday, August 5th at 10:59 AM ET.

Einstein Book Contest Flyer 2

To celebrate the 100th anniversary of Albert Einstein’s theory of general relativity, Princeton University Press launches books by Hanoch Gutfreund and Jürgen Renn

The Road to RelativityOn July 15th, Princeton University Press proudly launched two books by Professor Hanoch Gutfreund and Jürgen Renn, Relativity and The Road to Relativity, at the 14th Marcel Grossman meeting on relativistic physics in Rome.

The two books are being published to celebrate the 100th anniversary of Albert Einstein’s formulation of the theory of general relativity in 1915, and so it was fitting to launch them at a conference that demonstrates the ongoing influence of Einstein’s theory on cutting edge work on black holes, pulsars, quantum gravity, and other areas fundamental to our understanding of the universe.

The launch took place at the Besso Foundation, the family home of Albert Einstein’s friend and colleague, Michele Besso, during an exhibition, organized by Professor Gutfreund, of original Einstein letters and notebooks from the Albert Einstein Archives at the Hebrew University in Jerusalem.

relativity jacketMore than 150 distinguished physicists and invited guests, including the Chief Rabbi of Rome, Riccardo di Segni, and members of the Besso and Grossman families, listened to Professor Gutfreund and Professor Renn provide a compelling overview of their research and of the new insights it has brought to the history of the development of general relativity. Professor Gutfreund stressed the fundamental insights into Einstein’s work provided by the rich Archives in Jerusalem, while Renn dismissed the notion of Albert Einstein as an isolated and idiosyncratic genius, stressing his network of collaborators and colleagues, including Besso.


Renn and Gutfreund

Professor Hanoch Gutfreund and Jürgen Renn at the book launch in Rome

Photo from Renn and Gutfreund launch

Launch for Relativity and The Road to Relativity, at the 14th Marcel Grossman meeting on relativistic physics in Rome


Win a copy of Relativity: 100th Anniversary Edition by Albert Einstein through Corbis!

We are teaming with Corbis Entertainment to offer this terrific giveaway through their official Albert Einstein Facebook page. Contest details below, but please head over to the “official Facebook page of the world’s favorite genius” to enter!

Enter for a chance to win a FREE COPY of “Relativity: 100th Anniversary Edition” by Albert Einstein!

Two new exhibits about Albert Einstein on Google Cultural Institute


Two new, expertly written and illustrated exhibits about Albert Einstein are now available for free on Google Cultural Institute. These archives feature information from the Einstein Papers Project and the Hebrew University archives.

Einstein’s Trip to the Far East and Palestine

In late 1922 and early 1923, Albert Einstein embarked on a five-and-a-half-month trip to the Far East, Palestine, and Spain. In September 1921, Einstein had been invited by the progressive Japanese journal Kaizo to embark on a lecture tour of Japan.   The tour would include a scientific lecture series to be delivered in Tokyo, and six popular lectures to be delivered in several other Japanese cities. An honorarium of 2,000 pounds sterling was offered and accepted.

Einstein’s motivation for accepting the invitation to Japan was threefold: to fulfil his long-term desire to visit the Far East, to enjoy two long sea voyages “far from the madding crowds” and to escape from Berlin for several months in the wake of the recent assassination of Germany’s Foreign Minister Walther Rathenau, who had belonged to Einstein’s circle of friends. Rathenau had been gunned down by anti-Semitic right-wing extremists in June 1922 and there was reason to believe that Einstein’s life was also at risk.

Credit: Einstein’s Trip to the Far East and Palestine

Albert Einstein German, Swiss and American?

In a letter to his superiors, the German ambassador, Constantin von Neurath, quotes from a Copenhagen newspaper: „Although a Swiss subject by birth and supposedly of Jewish origin, Einstein’s work is nevertheless an integral part of German research“.

Von Neurath uses this flawed statement with good reason: The  Swiss Jew whom he would rather disregard, unfortunately proves to be one of the few “Germans” welcome abroad.

On April 26, 1920, for example, Albert Einstein was nominated member of the  Royal Danish Academy of Sciences and Letters.

The more appreciated Einstein becomes abroad, the greater Germany’s desire to claim him as one of their own.

Credit: Albert Einstein German, Swiss and American?

On the occasion of these exhibits, Diana K. Buchwald of the Einstein Papers Project at California Institute of Technology said, “The Einstein cultural exhibit gives us a splendid glimpse into rare documents and images that tell not only the story of Einstein’s extraordinary voyage to publicize relativity in Japan in 1922, and to lay the cornerstone of the Hebrew University in Palestine in 1923, but also the dramatic trajectory of his entire life, illustrated by his colorful passports that bear testimony to the vagaries of his personal life.”

Prof. Hanoch Gutfreund, Former President, The Hebrew University of Jerusalem, Chair of the Albert Einstein Archives echoed her Buchwald’s enthusiasm noting, “The cooperation between the Google Cultural Institute, the Hebrew University of Jerusalem and the Einstein Papers Project in Caltech has produced two exhibitions exploring two specific topics on Einstein’s life and personality. Thus, Google has provided an arena, accessible to all mankind, which allows the Hebrew University to share with the general public the highlights of one of its most important cultural assets–the Albert Einstein Archives, which shed light on Einstein’s scientific work, public activities and personal life.

Learn more about Princeton University Press’s Einstein-related books, including the print editions of the Einstein Papers Project, here.



A letter from Ingrid Gnerlich, Executive Editor of Physical and Earth Sciences

Photo on 2014-05-14Dear Readers:

As many of you will know, in November 2013, the remarkable astrophysicist, Dimitri Mihalas – a pioneering mind in computational astrophysics, and a world leader in the fields of radiation transport, radiation hydrodynamics, and astrophysical quantitative spectroscopy – passed away.  Though deeply saddened by this news, I also feel a unique sense of honor that, this year, I am able to announce the much-anticipated text, Theory of Stellar Atmospheres:  An Introduction to Astrophysical Non-equilibrium Quantitative Spectroscopic Analysis, co-authored by Ivan Hubeny and Dimitri Mihalas.  This book is the most recent publication in our Princeton Series in Astrophysics (David Spergel, advising editor), and it is a complete revision of Mihalas’s Stellar Atmospheres, first published in 1970 and considered by many to be the “bible” of the field.  This new edition serves to provide a state of the art synthesis of the theory and methods of the quantitative spectroscopic analysis of the observable outer layers of stars.  Designed to be self-contained, beginning upper-level undergraduate and graduate-level students will find it accessible, while advanced students, researchers, and professionals will also gain deeper insight from its pages.  I look forward to bringing this very special book to the attention of a wide readership of students and researchers.

It is also with profound excitement that I would like to announce the imminent publication of Kip Thorne and Roger Blandford’s Modern Classical Physics:  Optics, Fluids, Plasmas, Elasticity, Relativity, and Statistical Physics.  This is a first-year, graduate-level introduction to the fundamental concepts and 21st-century applications of six major branches of classical physics that every masters- or PhD-level physicist should be exposed to, but often isn’t.  Early readers have described the manuscript as “splendid,” “audacious,” and a “tour de force,” and I couldn’t agree more.  Stay tuned!

Lastly, it is a pleasure to announce a number of newly and vibrantly redesigned books in our popular-level series, the Princeton Science Library.  These include Richard Alley’s The Two-Mile Time Machine, which Elizabeth Kolbert has called a “fascinating” work that “will make you look at the world in a new way” (The Week), as well as G. Polya’s bestselling must-read, How to Solve It.  In addition, the classics by Einstein, The Meaning of Relativity, with an introduction by Brian Greene, and Feynman, QED, introduced by A. Zee, are certainly not to be missed.

Of course, these are just a few of the many new books on the Princeton list I hope you’ll explore.  My thanks to you all—readers, authors, and trusted advisors—for your enduring support. I hope that you enjoy our books and that you will continue to let me know what you would like to read in the future.

Ingrid Gnerlich
Executive Editor, Physical & Earth Sciences

Pi Day: “Was Einstein Right?” Chuck Adler on the twin paradox of relativity in science fiction

This post is extracted from Wizards, Aliens, and Starships by Charles Adler. Dr. Adler will kick off Princeton’s Pi Day festivities tonight with a talk at the Princeton Public Library starting at 7:00 PM. We hope you can join the fun!

For more Pi Day features from Princeton University Press, please click here.

Tfts56[1]Robert A. Heinlein’s novel Time for the Stars is essentially one long in-joke for physicists. The central characters of the novel are Tom and Pat Bartlett, two identical twins who can communicate with each other telepathically. In the novel, telepathy has a speed much faster than light. Linked telepaths, usually pairs of identical twins, are used to maintain communications between the starship Lewis and Clark and Earth. Tom goes on the spacecraft while Pat stays home; the ship visits a number of distant star systems, exploring and finding new Earth-like worlds. On Tom’s return, nearly seventy years have elapsed on Earth, but Tom has only aged by five.

I call this a physicist’s in-joke because Heinlein is illustrating what is referred to as the twin paradox of relativity: take two identical twins, fly one around the universe at nearly the speed of light, and leave the other at home. On the traveler’s return, he or she will be younger than the stay-at- home, even though the two started out the same age. This is because according to Einstein’s special theory of relativity, time runs at different rates in different reference frames.

This is another common theme in science fiction: the fact that time slows down when one “approaches the speed of light.” It’s a subtle issue, however, and is very easy to get wrong. In fact, Heinlein made some mistakes in his book when dealing with the subject, but more on that later. First, I want to list a few of the many books written using this theme:

  • The Forever War, by Joe W. Haldeman. This story of a long-drawn-out conflict between humanity and an alien race has starships that move at speeds near light speed to travel between “collapsars” (black holes), which are used for faster-than-light travel. Alas, this doesn’t work. The hero’s girlfriend keeps herself young for him by shuttling back and forth at near light speeds between Earth and a distant colony world.
  • Poul Anderson’s novel, Tau Zero. In this work, mentioned in the last chapter, the crew of a doomed Bussard ramship is able to explore essentially the entire universe by traveling at speeds ever closer to the speed of light.
  • The Fifth Head of Cerberus, by Gene Wolfe. In this novel an anthropologist travels from Earth to the double planets of St. Croix and St. Anne. It isn’t a big part of the novel, but the anthropologist John Marsch mentions that eighty years have passed on Earth since he left it, a large part of his choice to stay rather than return home.
  • Larris Niven’s novel A World out of Time. The rammer Jerome Corbell travels to the galactic core and back, aging some 90 years, while three million years pass on Earth.

There are many, many others, and for good reason: relativity is good for the science fiction writer because it brings the stars closer to home, at least for the astronaut venturing out to them. It’s not so simple for her stay-at-home relatives. The point is that the distance between Earth and other planets in the Solar System ranges from tens of millions of kilometers to billions of kilometers. These are large distances, to be sure, but ones that can be traversed in times ranging from a few years to a decade or so by chemical propulsion. We can imagine sending people to the planets in times commensurate with human life. If we imagine more advanced propulsion systems, the times become that much shorter.

Unfortunately, it seems there is no other intelligent life in the Solar System apart from humans, and no other habitable place apart from Earth. If we want to invoke the themes of contact or conflict with aliens or finding and settling Earth-like planets, the narratives must involve travel to other stars because there’s nothing like that close to us. But the stars are a lot farther away than the planets in the Solar System: the nearest star system to our Solar System, the triple star system Alpha Centauri, is 4.3 light-years away: that is, it is so far that it takes light 4.3 years to get from there to here, a distance of 40 trillion km. Other stars are much farther away. Our own galaxy, the group of 200 billion stars of which our Sun is a part, is a great spiral 100,000 light-years across. Other galaxies are distances of millions of light-years away.

From our best knowledge of physics today, nothing can go faster than the speed of light. That means that it takes at least 4.3 years for a traveler (I’ll call him Tom) to go from Earth to Alpha Centauri and another 4.3 years to return. But if Tom travels at a speed close to that of light, he doesn’t experience 4.3 years spent on ship; it can take only a small fraction of the time. In principle, Tom can explore the universe in his lifetime as long as he is willing to come back to a world that has aged millions or billions of years in the meantime.


Was Einstein Right?

This weird prediction—that clocks run more slowly when traveling close to light speed—has made many people question Einstein’s results. The weirdness isn’t limited to time dilation; there is also relativistic length contraction. A spacecraft traveling close to the speed of light shrinks in the direction of motion. The formulas are actually quite simple. Let’s say that Tom is in a spacecraft traveling along at some speed v, while Pat is standing still, watching him fly by. We’ll put Pat in a space suit floating in empty space so we don’t have to worry about the complication of gravity. Let’s say the following: Pat has a stopwatch in his hand, as does Tom. As Tom speeds by him, both start their stopwatches at the same time and Pat measures a certain amount of time on his watch (say, 10 seconds) while simultaneously watching Tom’s watch through the window of his spacecraft. If Pat measures time ∆t0 go by on his watch, he will see Tom’s watch tick through less time. Letting ∆t be the amount of time on Tom’s watch, the two times are related by the formula

where the all-important “gamma factor” is

The gamma factor is always greater than 1, meaning Pat will see less time go by on Tom’s watch than on his. Table 12.1 shows how gamma varies with velocity.

Note that this is only really appreciable for times greater than about 10% of the speed of light. The length of Tom’s ship as measured by Pat (and the length of any object in it, including Tom) shrinks in the direction of motion by the same factor.

Even though the gamma factor isn’t large for low speeds, it is still measurable. To quote Edward Purcell, “Personally, I believe in special relativity. If it were not reliable, some expensive machines around here would be in very deep trouble”. The time dilation effect has been measured directly, and is measured directly almost every second of every day in particle accelerators around the world. Unstable particles have characteristic lifetimes, after which they decay into other particles. For example, the muon is a particle with mass 206 times the mass of the electron. It is unstable and decays via the reaction

It decays with a characteristic time of 2.22 μs; this is the decay time one finds for muons generated in lab experiments. However, muons generated by cosmic ray showers in Earth’s atmosphere travel at speeds over 99% of the speed of light, and measurements on these muons show that their decay lifetime is more than seven times longer than what is measured in the lab, exactly as predicted by relativity theory. This is an experiment I did as a graduate student and our undergraduates at St. Mary’s College do as part of their third-year advanced lab course. Experiments with particles in particle accelerators show the same results: particle lifetimes are extended by the gamma factor, and no matter how much energy we put into the particles, they never travel faster than the speed of light. This is remarkable because in the highest-energy accelerators, particles end up traveling at speeds within 1 cm/s of light speed. Everything works out exactly as the theory of relativity says, to a precision of much better than 1%.

How about experiments done with real clocks? Yes, they have been done as well. The problems of doing such experiments are substantial: at speeds of a few hundred meters per second, a typical speed for an airplane, the gamma factor deviates from 1 by only about 1013. To measure the effect, you would have to run the experiment for a long time, because the accuracy of atomic clocks is only about one part in 1011 or 1012; the experiments would have to run a long time because the difference between the readings on the clocks increases with time. In the 1970s tests were performed with atomic clocks carried on two airplanes that flew around the world, which were compared to clocks remaining stationary on the ground. Einstein passed with flying colors. The one subtlety here is that you have to take the rotation of the Earth into account as part of the speed of the airplane. For this reason, two planes were used: one going around the world from East to West, the other from West to East. This may seem rather abstract, but today it is extremely important for our technology. Relativity lies at the cornerstone of a multi-billion-dollar industry, the global positioning system (GPS).

GPS determines the positions of objects on the Earth by triangulation: satellites in orbit around the Earth send radio signals with time stamps on them. By comparing the time stamps to the time on the ground, it is possible to determine the distance to the satellite, which is the speed of light multiplied by the time difference between the two. Using signals from at least four satellites and their known positions, one can triangulate a position on the ground. However, the clocks on the satellites run at different rates as clocks on the ground, in keeping with the theory of relativity. There are actually two different effects: one is relativistic time dilation owing to motion and the other is an effect we haven’t considered yet, gravitational time dilation. Gravitational time dilation means that time slows down the further you are in a gravitational potential well. On the satellites, the gravitational time dilation speeds up clock rates as compared to those on the ground, and the motion effect slows them down. The gravitational effect is twice as big as the motion effect, but both must be included to calculate the total amount by which the clock rate changes. The effect is small, only about three parts in a billion, but if relativity weren’t accounted for, the GPS system would stop functioning in less than an hour. To quote from Alfred Heick’s textbook GPS Satellite Surveying,

Relativistic effects are important in GPS surveying but fortunately can be accurately calculated. . . . [The difference in clock rates] corresponds to an increase in time of 38.3 μsec per day; the clocks in orbit appear to run faster. . . . [This effect] is corrected by adjusting the frequency of the satellite clocks in the factory before launch to 10.22999999543 MHz [from their fundamental frequency of 10.23 MHz].

This statement says two things: first, in the dry language of an engineering handbook, it is made quite clear that these relativistic effects are so commonplace that engineers routinely take them into account in a system that hundreds of millions of people use every day and that contributes billions of dollars to the world’s commerce. Second, it tells you the phenomenal accuracy of radio and microwave engineering. So the next time someone tells you that Einstein was crazy, you can quote chapter and verse back at him!

Fantasy Physics: Should Einstein Have Won Seven Nobel Prizes?

This guest post from A. Douglas Stone is part of our celebration of all things Einstein, pi, and, of course, pie this week. For more articles, please click here. Please join Prof. Stone at the Princeton Public Library on March 14 at 6 PM for a lecture about Einstein’s quantum breakthroughs.

Cross-posted with the Huffington Post.

Thanks to RealClearScience for posting about this article!!

2014-03-12-Albert_Einstein_28Nobel291.pngAlbert Einstein never cared too much about receiving awards and honors, and that included the Nobel Prizes, which were established in 1901, at roughly the same time as Einstein was beginning his research career in physics. In 1905, at the age of 25, Einstein began his ascent to scientific pre-eminence and world-wide fame with his proposal of the Special Theory of Relativity, as well as a “revolutionary” paper on the particulate properties of light, his foundational work on molecular (“Brownian”) motion, and finally his famous equation, E = mc2. In 1910, he was first nominated for the Prize and was nominated many times subsequently, usually by multiple physicists, until he finally won the 1921 Prize (awarded in 1922). Surprisingly, he did not win for his most famous achievement, Relativity Theory, which was still deemed too speculative and uncertain to endorse with the Prize. Instead, he won for his 1905 proposal of the law of the photoelectric effect—empirically verified in the following decade by Robert Millikan—and for general “services to theoretical physics.” It was a political decision by the Nobel committee; Einstein was so renowned that their failure to select him had become an embarrassment to the Nobel institution. But this highly conservative organization could find no part of his brilliant portfolio that they either understood or trusted sufficiently to name specifically, except for this relatively minor implication of his 1905 paper on particles of light. The final irony in this selection was that, among the many controversial theories that Einstein had proposed in the previous seventeen years, the only one not accepted by almost all of the leading theoretical physicists of the time was precisely his theory of light quanta (or photons), which he had used to find the law of the photoelectric effect!

In keeping with his relative indifference to such honors, Einstein declined to attend the award ceremony, because he had previously committed to a lengthy trip to Japan at that time and didn’t feel it was fair to his hosts to cancel it. Moreover, when the Prize was officially announced and the news reached him during his long voyage to Japan, he neglected to even mention the Prize in the travel diary he was keeping. He had taken one practical note of it however, in advance. When he divorced his first wife, Mileva Maric in 1919, he agreed to transfer to her the full prize money, a substantial sum, in the form of a Trust for the benefit of her and his sons, should he eventually win.

However, while Einstein himself barely dwelt at all on this honor, it is an interesting exercise to ask how many distinct breakthroughs Einstein made during his productive research career, spanning primarily the years 1905 to 1925, that could be judged of Nobel caliber, when placed in historical context and evaluated by the standards of subsequent Nobel Prize awards. Admittedly, this analysis has a bit in common with fantasy sports, in which athletes are judged and ranked by their statistical achievements and arguments are made about who was the GOAT (“greatest of all time”). Well, why not spend a few pages on this guilty pleasure, at least partly in the service of illuminating the achievements of this historic genius, even if Einstein would not have approved?

Let’s start with the Prize he did receive, which was absolutely deserved, if the committee had had the courage to write the citation, “for his proposal of the existence of light quanta.” The law of the photoelectric effect, which they cited, only makes sense if light behaves like a particle in some important respects, and that is what he proposed in 1905. This proposal came at a time when the wave theory of light was absolutely triumphant and was even enshrined in a critical technology: radio. Not a single physicist in the world was thinking along similar lines as Einstein, nor were all of the important theorists convinced by his arguments for two more decades. Nonetheless, the photon concept was unambiguously confirmed in experiments by 1925, and now is considered the paradigm for our modern quantum theory of force-carrying particles. It is the first in a family of particles known as bosons, most recently augmented by the (Nobel-winning) discovery of the Higgs particle. So the photon is a Nobel slam dunk.

We can move next to two more “no-brainers,” the two theories of relativity, the Special Theory, proposed in 1905, and the General Theory, germinated in 1907 and completed in 1915. These are quite distinct contributions. The Special Theory introduced the Principle of Relativity, that the law of physics must all be the same for bodies in uniform relative motion. An amazing implication of this statement is that time does not elapse uniformly, independent of the motion of observers, but rather that the time interval between events depends on the state of relative motion of the observer. Einstein was the first to understand and explain this radical notion, which is now well-verified by direct experiments. Moreover, Einstein’s concept of “relativistic invariance” is built into our theory of the elementary particles, and so it has had a profound impact on fundamental physics. However, here it must be noted that the equations of Special Relativity were first written down by Hendrik Lorentz, the great Dutch physicist whom Einstein admired the most of all his contemporaries. Lorentz just failed to give them the radical interpretation with which Einstein endowed them; he also failed to notice that they implied that energy and mass were interchangeable: E = mc2. There are also a few votes out there for the French mathematician, Henri Poincare, who enunciated the Principle of Relativity before Einstein, but I can’t put him in the same category as Lorentz with regard to this debate. Einstein would have been happy to share Special Relativity with Lorentz, so let’s split this one 50-50 between the two.

General Relativity on the other hand is all Albert. Like the photon, no one on the planet even had an inkling of this idea before Einstein. Einstein realized that the question of the relativity of motion was tied up with the theory of Gravity: that uniform acceleration (e.g. in an elevator in empty space) was indistinguishable from the effect of gravity on the surface of a planet. It gave one the same sense of weight. From this simple seed of an idea arose arguably the most beautiful and mathematically profound theory in all of physics, Einstein’s Field Equations, which predict that matter curves space and that the geometry of our universe is non-Euclidean in general. The theory underlies modern cosmology and has been verified in great detail by multiple heroic and diverse experiments. The first big experiment, which measured the deflection of starlight as it passed by the sun during a total eclipse, is what made Einstein a worldwide celebrity. This one is probably worth two Nobel prizes, but let’s just mark it down for one.

Here we exhaust what most working physicists would immediately recognize as Einstein’s works of genius, and we’re only at 2.5 Nobels. But it is a remarkable fact that Einstein’s work on early atomic theory, what we now call quantum theory, is vastly under-rated. This is partially because Einstein himself downplayed it due to his rejection of the final version of the theory, which he dismissed with the famous phrase, “God does not play dice.” But if one looks at what he actually did, the Nobels keep piling up.

The modern theory of the atom, quantum theory, began in 1900 with the work of the German physicist, Max Planck, who, in what he called “an act of desperation,” introduced into physics a radical notion, quantization of energy. Or so the textbooks say. This is the idea that when energy is exchanged between atoms and radiation (e.g. light), it can only happen in discrete chunks, like a parking meter that only accepts quarters. This idea turns out to be central to modern atomic physics, but Planck didn’t really say this in his work. He said something much more provisional and ambiguous. It was Einstein in his 1905 paper—but then much more clearly in a follow-up paper on the vibrations of atoms in solids in 1907—who really stated the modern principle. It is not clear if Planck himself accepted it fully even a decade after his seminal work (although he was given credit for it by the Nobel Prize committee in 1918). In contrast, Einstein boldly applied it to the mechanical motion of atoms, even when they are not exchanging energy with radiation, and stated clearly the need for a quantized mechanics. So despite the textbooks, Einstein clearly should have shared Planck’s Nobel Prize for the principle of quantization of energy. We are up to 3.0 Nobels for Big Al.

The next one in line is rarely mentioned. After Einstein proposed his particulate theory of light in 1905, he did not adopt the view that light was simply made of particles in the ordinary sense of a localized chunk of matter, like a grain of sand. Instead, he was well aware that light interfered with itself in a similar manner to water waves (a peak can cancel a trough, leading to no wave). In 1909, he came up with a mathematical proof that the particle and wave properties were present in one formula that described the fluctuations of the intensity of light. Hence, he announced that the next era of theoretical physics would see a “fusion” of the particle and wave pictures into a unified theory. This is exactly what happened, but it took fourteen years for the next advance and another three (1926) for it all to fall into place. In 1923, the French physicist Louis de Broglie hypothesized that electrons, which have mass (unlike light) and were always previously conceived of as particles, actually had wavelike properties similar to light. He freely admitted his debt to Einstein for this idea, but when he got the Nobel Prize for “wave-particle” duality in 1929, it was not shared. But it should have been. Another half for Albert, at 3.5 and counting.

From 1911 to 1915 Einstein took a vacation from the quantum to invent General Relativity, which we have already counted, so his next big thing was in 1916 (he didn’t leave a lot of dead time in those days). That was three years after Niels Bohr introduced his “solar system” model of the atom, where the electrons could only travel in certain “allowed orbits” with quantized energy. Einstein went back to thinking about how atoms would absorb light, with the benefit of Bohr’s picture. He realized that once an atom had absorbed some light, it would eventually give that light energy back by a process called spontaneous emission. Without any particular event to cause it, the electron would jump down to a lower energy orbit, emitting a photon. This was the first time that it was proposed that the theory of atoms had such random, uncaused events, a notion that became a second pillar of quantum theory. In addition, he stated that sometimes there was causal emission, that the imposition of more light could cause the atom to release its absorbed light energy in a process called stimulated emission. Forty-four years later, physicists invented a device that uses this principle to produce the purest and most powerful light sources in nature, the LASER (Light Amplified by Stimulated Emission of Radiation). The principles of spontaneous and stimulated emission introduced by Einstein underlie the modern quantum theory of light. One full Prize please—now at 4.5.

After that 1916-1917 work, Einstein had some health problems and became involved in political and social issues for a while, leading to a Nobel batting slump for a few years. (He did still collect some hits, like the prediction of gravitational waves (a double) and the first paper on cosmology and the geometry of the Universe using General Relativity (a triple)). But he came out of his slump with a vengeance in 1924 when he received a paper out of the blue from an unknown Indian, physicist Satyendranath Bose. It was yet another paper about particles of light, and although Bose did not state his revolutionary idea very clearly, reading between the lines, Einstein detected a completely new principle of quantum theory, the idea that all fundamental particles are indistinguishable. This is the standard terminology in physics, but it is actually very misleading. Here, indistinguishability is not the idea that humans can’t tell two photons apart (like identical twins); it is the idea that Nature can’t tell them apart, and in a real sense interchanging the two photons doesn’t count as a different state of light.

When Bose applied this principle to light he didn’t get anything radically new; it was just a different way of thinking about Planck’s original discovery in 1900. But Einstein then took the principle and applied it to atoms for the very first time, with amazing results. He discovered that a simple gas of atoms, if cooled down sufficiently, would cease to obey all the laws that physicists and chemist had discovered for gases over the centuries, and to which no exception had ever been found. Instead, all gases should behave like a weird liquid or super-molecule known as a Bose-Einstein condensate. But remember, Bose had no clue this would happen; he didn’t even try to apply his principle to atoms. It turns out that Einstein condensation underlies some of the most dramatic quantum effects, such as superconductivity, which is needed to make the magnets in MRI machines and has been the basis for five Nobel Prizes. No knowledgeable physicist would dispute that Einstein deserved a full Nobel Prize for this discovery, but I am sure that Einstein would have wanted to share it with Bose (who never did receive the Prize).

So we are at 5.0 “units” of Nobel Prize but seven trips to Stockholm. And this leaves out other arguably Nobel-caliber achievements (Brownian motion as well as the Einstein-Podolsky-Rosen effect, which underlies modern quantum information physics). And wait a minute—when someone shares the Nobel Prize do we refer to them as a “half- Laureate”? No way. Even scientists who get a “measly” third of a Prize are Nobel Laureates for life. Thus by the standard we apply to normal humans, Einstein deserved at least seven Nobel Prizes. So next time you make your fantasy scientist draft, you know who to take at number one.

Stone_EinsteinQuantum_jktA. Douglas Stone is author of Einstein and the Quantum: The Quest of The Valiant Swabian.

Einstein’s Real Breakthrough: Quantum Theory

Thank you to Yale University for recording this fantastic interview between A. Douglas Stone and Ramamurti Shankar.

People may be surprised to hear that Einstein could well be the father of quantum theory in addition to the father of relativity. In part this is because Einstein ultimately rejected quantum theory, but also because there is very little published evidence of his work. However, as he researched his new book Einstein and the Quantum: The Quest of the Valiant Swabian, Stone discovered letters and correspondence with other scientists that demonstrate the extent of Einstein’s influence in this area.

If you would like to learn more about Einstein’s contributions to quantum theory, grab a copy of Einstein and the Quantum which you can sample here.

Interested in Einstein?



On Wednesday 29th January, A.Douglas Stone will be giving a talk at Blackwell’s Bookshop, Oxford, one of Britain’s best loved and most famous bookshops.

Einstein’s development of Quantum theory has not really been appreciated before. Now A.Douglas Stone reveals how he was actually one of the most important pioneers in the field.  Einstein himself famously rejected Quantum mechanics with his “God does not play dice” theory, yet he actually thought more about atoms and molecules than he did about relativity. Stone’s book ‘Einstein and the Quantum‘, which was published in November by Princeton University Press, outlines Einstein’s personal struggle with his Quantum findings as it went against his belief in science as something eternal and objective. Professor Stone will be happy to take questions and sign copies at the end of his talk.

Wednesday, January 29th at 19:00

Tickets cost £3 and are available from Blackwell’s Customer Service desk in the shop; by telephoning 01865 333623; by emailing events.oxford@blackwell.co.uk


Q&A with Douglas Stone, Author of “Einstein and the Quantum”

Einstein and the QuantumA. Douglas Stone is the Carl A. Morse Professor of Applied Physics and Physics at Yale University. His book, Einstein and the Quantum: The Quest of the Valiant Swabian, reveals for the first time the full significance of Albert Einstein’s contributions to quantum theory. Einstein famously rejected quantum mechanics, observing that God does not play dice. But, in fact, he thought more about the nature of atoms, molecules, and the emission and absorption of light–the core of what we now know as quantum theory–than he did about relativity.

In a recent interview, A. Douglas Stone talked about Einstein’s contributions to the scientific community, quantum theory, and his new book, Einstein and the Quantum: The Quest of the Valiant Swabian.

Why does quantum theory matter?
At the beginning of the 20th century science was facing a fundamental roadblock: scientists did not understand the laws governing the atoms and molecules of which all materials are made, but which are unobservable due to their size.

At that time there was a real question whether the human mind was capable of understanding this microscopic realm, outside of all our direct experience of the world.  The development and success of quantum theory was a turning point for modern civilization, enabling most of the scientific advances and revolutionary technologies of the century that followed.

What are some of the ways that quantum theory has changed our lives?
There is a common misconception that quantum mechanics is mainly about very weird phenomena, remote from everyday life, such as Schrodinger’s cat, exotic sub-atomic particles, black holes, or the Big Bang.  Actually it is a precise quantitative tool to understand the materials, chemical reactions and devices we employ in modern industries, such as semiconductors, solar cells, and lasers.  An early success of the quantum theory was to help predict how to extract ammonia from the air, which could then be used as fertilizer for the green revolution that revolutionized 20th century agriculture. And of course our ability to develop both nuclear weapons and nuclear power was completely dependent upon quantum theory.

Why is Einstein’s role in quantum theory important and interesting?
It is important because a careful examination of the historical record shows that Einstein was responsible for more of the fundamental new concepts of the theory than any other single scientist.  This is arguably his greatest scientific legacy, despite his fame for Relativity Theory.  He himself said, “I have thought a hundred times more about the quantum problems than I have about Relativity Theory”. It is interesting because he ultimately refused to accept quantum theory as the ultimate truth about Nature, because it violated his core philosophical principles.

So you are saying that Einstein is famous for the wrong theory?
In a certain sense, yes.  All physicists agree that the theory of relativity, particularly general relativity, is a work of staggering individual genius.  But in terms of impact on human society and history, quantum mechanics is simply much more important.  In fact, relativity theory is incorporated into important parts of modern quantum mechanics, but in many contexts it is irrelevant.

In what ways was Einstein central to the development of the theory?
I estimate that his contributions to quantum theory would have been worthy of four Nobel Prizes if different scientists had done them, compared to the one that he received. I go through each of these contributions in its historical and biographical context in the book.

Can you give a few examples?
Quantum theory gets its name because it says that certain physical quantities, including the energies of electrons bound to atomic nuclei are quantized, meaning that only certain energies are allowed, whereas in macroscopic physics energy is a continuously varying quantity.  Typically the German physicist, Max Planck, is credited with the insight that energy must be quantized at the molecular scale, but the detailed history shows Einstein role in this conceptual breakthrough was greater.
Another key thing in quantum theory is that fundamental particles, while they move in space, sometimes behave as if they were spread out, like a wave in water, but in other contexts they appear as particles, i.e. very localized point-like objects.  Einstein introduced this “wave-particle duality” first, in 1905 (his “miracle year”), when he proposed that light, long thought to be an electromagnetic wave, also could behave like a particle, now known as the photon.
Yet another, very unusual concept in quantum theory is that fundamental particles, such as photons, are “indistinguishable” in a technical sense.  When many photons are bunched together it makes no sense to ask which is which.  This changes their physical properties in a very important way, and this insight is often attributed to the Indian physicist, S. N. Bose (hence the term “boson”).  In my view Einstein played a larger role in this advance than did Bose, although he always very generously gave Bose a great deal of credit.
The stories of these and other findings are fully told in the book and they illustrate new aspects of Einstein’s genius, unknown to the public and even to many working scientists.

What did Einstein object to about quantum theory?
Initially he reacted strongly against the intrinsic randomness and uncertainty of quantum mechanics, saying “God does not play dice”.  But after that his main objection was that quantum theory seems to break down the distinction between the subjective world of human experience and the objective description of physical reality that he considered the goal of physics, and his central mission in life. Many physicists struggle with this issue even today.

Why is Einstein’s role in quantum theory underappreciated?
Einstein ultimately rejected the theory and moved on to other areas of research, so he never emphasized the extent of his contributions.  His own autobiographical notes, written in his seventies, understate his role to an almost laughable degree. Second, Einstein’s version of quantum theory, wave mechanics, did not create a school of followers, whereas Niels Bohr, Werner Heisenberg and others reached the same point be a different route. Their school fostered the primary research thrust in atomic and nuclear physics, gradually causing the memory of Einstein’s role to fade.  Finally, the history of Einstein’s involvement with quantum theory was long (1905-1925) and complex, and few people really understand it all; I try to remedy that in this book.

Did Einstein do anything important in quantum physics after the basic theory was known?
No and yes.  He did not work in the main stream of elementary particle physics which developed shortly after the basic theory was discovered in the late nineteen twenties, since he refused to employ the standard mathematical machinery of quantum theory which everyone else used.  However, in the early 1930’s he identified a conceptual feature of quantum theory missed by all the other pioneers, which became known by the term “entanglement”. This concept, ironically, is critical to the most revolutionary area of modern quantum physics, quantum information theory and quantum computing.

What does the subtitle of the book refer to? Who is the “Valiant Swabian”?
The Valiant Swabian was a fictional crusader knight, the hero of a poem by Ludwig Uhland, a poet from Swabia where Einstein was born. In his twenties, Einstein used to refer to himself jokingly by this name, particularly with his first wife, Mileva Maric.  It was a similar to someone today calling himself “Indiana Jones” for fun.  The young Einstein was a charismatic and memorable personality, with great joie de vivre, as this nickname indicates.  He was known for his sense of humor, his rebelliousness, and for his attractiveness to women, in contrast to the benevolent, grandfatherly, star-gazer we associate with iconic pictures of the white-maned sage of later years.

How did you research this book? What materials did you have access to?
There is a very extensive trove of letters and private papers that survive in Einstein’s estate, all of which have been translated and published for the period 1886 to 1922.  From reading all of these I got a good sense of his personality.  And all of his important scientific papers in the relevant time period are available in English now, so I was able to go back and see exactly how he arrived at his revolutionary ideas about quantum theory, which I then did my best to interpret in layman’s terms. In addition I relied on several excellent biographies by Folsing, Isaacson and Pais, and historical articles by many leading historians of science, such as T.S. Kuhn and Martin Klein.

What do you hope readers take away from reading Einstein and the Quantum?
First, new insight into Einstein’s genius, and a sense of the personality of the young Einstein, before his fame. Second, appreciation of the historic significance of the successful attempt to understand the atom through quantum theory, a turning point in human civilization. Third, an understanding of how science advances as a creative, human process, with both brilliant insights and embarrassing blunders, affected by psychological and philosophical influences.

Why has Nikola Tesla become a countercultural hero?

This video was taped at a recent event at the Johns Hopkins University bookstore. The speaker here is W. Bernard Carlson, author of Tesla: Inventor of the Electrical Age.