Time and the freedom to think

The other day, I was complaining to a colleague that the academic system, with its constant pressure to publish or perish, did not encourage real breakthroughs to be made in science, because it encourages scientists to tackle the easiest problems that will allow them to publish fast. I have just stumbled upon this quotation, which perfectly supports my point (see also this quotation by Einstein).

"Julian Barbour is known to many who follow science as the author of The End of Time, in which he argues that time is an illusion. He is an unusual physicist, who, since receiving his doctorate in 1968 from the University of Cologne, has never held an academic job. But he has been highly influencial among the small group of people who think seriously about quantum gravity, for it was he who taught us what it means to make a background-independent theory.
As Barbour tells it, on a climbing trip during graduate school, he was seized by a vision that time might be an illusion. This led him to investigate the roots of our understanding of time, contained in the general theory of relativity. He realized that he could not make a conventional academic career worrying about the nature of time. He also realized that if he was going to work on that problem, he would have to concentrate on it fully, without being distracted by the pressures of a normal career in physics. So he bought an old farmhouse in a little village half an hour from Oxford, brought his new wife there, and settled down to think about time. It was ten years or so before he had something to report back to his colleagues. During that period, he and his wife had four children, and he worked part-time as a translator to support them. The translating took him no more than twenty hours a week, leaving him as much time for thinking as most academic scientists have after the responsabilities of teaching and administration are taken into account.
To get a bearing on the meaning ot time in general relativity, Barbour read deeply into the subject, working his way back through the history of physics and philosophy. He finally was able to invent a new kind of theory, in which space and time are nothing but a system of relationships. His papers on this subject slowly began to be noticed, and eventually he became an honored member of the quantum-gravity community. His reinterpretation of Einstein's general theory of relativity as a relational theory is now the way we in the field understand it.
This is not nearly all that Barbour has done, but it's enough to show how the career of a successful seer differs from that of a conventional academic scientist. Such a person does not follow fashion — in fact, probably does not even follow a field well enough to know what the fashion is. People like this are driven by nothing except a conviction, gained early, that everyone else is missing something crucial. Their approach is more scholarly, in that to think clearly they have to read through the whole history of the question that obsesses them. Their work is intensely focused, yet it takes them a long time to get somewhere. In furtherance of an academic career there is no output whatsoever. Julian Barbour, when he was ready, changed science more than most academic scientists have, but at an age when most academic physicists are up for tenure, he had absolutely nothing to show for his work.
Barbour's career resembles that of other seers, like Charles Darwin, who also retreated to the English countryside to find the room to think through an idea that obsessed him. Einstein spent ten years thinking about the ideas that became special relativity, and then spent the next ten inventing general relativity. Time and the freedom to think, then, are all that a seer needs to find that unexamined assumption. The rest they do themselves."

Lee Smolin, "The trouble with physics" (p. 321-322).

The scientists quest

"[...] how difficult it is to try to wrest precious, fundamental secrets from nature. That quest can be compared to climbing a mountain, and when reaching the peak, seeing another higher mountain that tempts us to ascend to even greater heights. And when we do reach the higher peak, we discover as we look across the valley yet another peak that calls. In the end, it is the wonderful experience of scaling the mountain — of attempting to understand the secrets of nature — that motivates us as scientists. There is of course the additional thrill, upon reaching the top of a mountain, to ram in the flagpole announcing one's victory. But that is only a momentary emotion soon superseded by the new challenges presented by the higher peak on the horizon.
[...] I believe that with the ascent of each mountain — each theory, each paradigm — we reach a new truth, but that no mountain peak can ever represent the ultimate theory of nature."

John W. Moffat, "Reinventing gravity" (p. 222).

De la nécessité morale de bien communiquer

« Une mauvaise écriture est une des formes du mépris qu’on a pour autrui; car elle prouve qu’on attache plus de prix à son propre temps qu’à celui des autres. »

Hugo de Groot

Make sure you have data first

"I have no data yet. It is a capital mistake to theorize before one has data. Insensibly, one begins to twist facts to suit theories instead of theories to suit facts."

Sir Arthur Conan Doyle (Sherlock Holmes), as quoted by John W. Moffat in "Reinventing gravity" (p. 156).

This statement means the same thing as that one from Feynman.

Critique du scepticisme?

Nous avons l'habitude en science de cultiver un certain scepticisme à l'égard de tout résultat scientifique, ce que nous considérons comme une attitude saine pour ne pas tomber dans le dogmatisme. Je suis donc un peu surpris de lire ce qui m'apparaît comme une critique du scepticisme venant du philosophe allemand Emmanuel Kant:

"La critique de la raison conduit donc nécessairement, en fin de compte, à la science ; l'usage dogmatique de la raison, sans critique, conduit au contraire à des affirmations sans fondement, auxquelles on peut opposer d'autres affirmations tout aussi spécieuses, par conséquent au scepticisme."

Emmanuel Kant, Critique de la raison pure, Introduction.

Peut-être Kant n'utilise-t'il pas le terme "scepticisme" sous le même sens que nous lui donnons de nos jours...

It is all about perseverance

"It's not that I'm so smart. It's just that I stay with problems longer."

Albert Einstein, quoted by Lee Smolin (The trouble with physics, p. 309).

What is a good scientist?

"Good scientists expect that their students will exceed them. Although the academic system gives a successful scientist many reasons to believe in his or her own authority, any good scientist knows that the minute you succumb to believing that you know more than your best students, you cease to be a scientist."

Lee Smolin, "The trouble with physics" (p. 304).

May I always remember this!

Force-carrying particles

I always have had a hard time understanding the concept of force-carrying particles : the idea I had understood was that you can describe the interaction between two particles either by the action of the forces created by the fields associated with each particle, or by new particles that each original particle exchanged with the other, therefore transferring momentum from one particle to the other, hence altering their trajectories. I could make sense of this as long as the interaction was repulsive, as such a momentum transfer would push the particles away from each other. But how could particles get attracted to each other with such a process? This does not make sense to me.

Then, I read the following passage in Lee Smolin book "The trouble with physics" (p. 85): "[...]each gravitational wave could be seen quantum mechanically, as a particle called the graviton - analogous to the photon, which is the quantum of the electromagnetic field."

I thought I had finally understood the concept of force-carrying particle : according to general relativity, the gravitational force is nothing but the deformation of space-time by the presence of mass, which causes objects to move otherwise than in uniform rectilinear motion, hence making us invoke a force, gravity, to explain their motion according to Newton's Second Law. Now, assume that a mass is suddenly placed somewhere in space-time. Its deformation of space-time will propagate at a finite speed, that of light, making its effect felt at greater and greater distances. These are gravitational waves. In analogy with electro-magnetic waves, which are quantized in photons, gravitational waves are quantized in gravitons, which are therefore the particles "carrying" the gravitational force, i.e., making its effects felt at distance.

This at last made sense to me. But then I watched the DVD version of Brian Greene's book "The elegant universe", in which there is an animation showing two persons throwing small balls at each other, and getting attracted toward each other as they throw the balls harder and harder. So we are back to this idea of momentum exchange, and this does not make sense to me for explaining attractive forces such as gravity!

Is there a theoretical physicist around who could help me understand this better?

What kind of scientist are you?

"As I reflect on the scientific careers of the people I have known these last thirty years, it seems to me more and more that these career decisions hinge on character. Some people will happily jump on the next big thing, give it all they've got, and in this way make important contributions to fast-moving fields. Others just don't have the temperament to do this. Some people need to think through everything very carefully, and this takes time, as they get easily confused. It's not hard to feel superior to such people, until you remember that Einstein was one of them. In my experience, the truly shocking new ideas and innovations tend to come from such people. Still others — and I belong to this third group — just have to go their own way, and will flee fields for no better reason than that it offends them that some people are joining in because it feels good to be on the winning side. So I no longer get bothered when I disagree with what other people are doing, because I see that temperament pretty much determines what kind of science they will do. Luckily for science, the contributions of the whole range of types are needed. Those who do good science, I've come to think, do so because they choose problems that are suited to them."

Lee Smolin, "The trouble with physics" (p. 95).

I think I belong to the second group of scientists who need to think through everything very carefully and get easily confused, although don't expect shocking new ideas and innovations to come out of me! What about you, dear reader?

How do you know whether you have really understood something?

"The physicist Ernest Rutherford once said, in essence, that if you can't explain a result in simple, nontechnical terms, then you don't really understand it. He wasn't saying that this means your result is wrong; rather, he was saying that it means you do not fully understand its origin, meaning, or implications."

Brian Greene, "The elegant universe" (p. 203).

This rejoins this famous French quotation:

"Ce que l'on conçoit bien s'énonce clairement,
Et les mots pour le dire arrivent aisément."

Nicolas Boileau, "L'Art poétique".

Climate models

Although I often criticize numerical models, since they often don't manage to reproduce correctly the observations I am working on, I have to recognize the following statement by Mark Lynas:

"Nevertheless, many skeptics base their objections on the suspicion that models are somehow fiddled in advance to come up with the "right answers" by scientists eager for the next global warming grant - "you get out what you put in", as the old adage goes. But climate models do have an important grounding: they are based not on subjective judgments by their constructors but on the fundamental laws of physics. These observable physical laws, governing everything from convection within clouds to the reflectivity of sea ice, cannot be changed by anyone, whatever their politics. After all, models don't do anything magical. All they do is solve physical equations. All the processes of HadCM3, for instance, could theoretically be worked out by hand - except that it would then take centuries of human labor to complete one "model run". What computers do is speed up the process, just as pocket calculators speed up mathematics lessons in school.
No one, however, suggests that models are perfect. They all tend to come out with slightly different answers to the same question, a reflection of their varying design. The reason here is that some of the physical laws that underpin them are not known precisely. How clouds interact with the wider atmosphere is a big uncertainty, for example, so some cloud model parameters are best guesses. Nor is it known exactly how far sulphate "aerosols" - tiny particles of pollution blamed for "global dimming" - cool things down. But models are a useful tool and give a valuable insight into likely future conditions on this planet - something humanity has never had access to before. Unlike the oracles consulted by the ancients, models offer a way of divining the future based not on the miraculous visions of some unseen prophetess but on observable physical data."

Mark Lynas, Six degrees - our future on a hotter planet, chapter "three degrees".

The present task for climate scientists is to improve our understanding of the physical relationships between different processes and parts of the earth system that are still not known precisely, and not well represented in climate models, in order to reduce the uncertainties in the forecasts of our future climate, and check that some neglected processes may not hold big surprises! For example, the IPCC's 2007 report forecasts between 18 and 59 centimeters of sea level rise by 2100, but acknowledges that uncertainties about ice-sheet response time to global warming were not taken into account because the physical processes involved had not yet been studied enough to allow for a reliable assessment of their potential effects. Since the Greenland and West Antarctic ice sheets contain enough ice for a multi-meter sea level rise, understanding the physical processes controlling ice sheet stability is an urgent scientific question to address, with primordial societal relevance.

Being a dynamic incompetent

"Young man," the Austrian said gravely, "a disaster happens to many, many of our best scientists. They become administrators. And the day they do that, they're lost to science. So you never want to become an administrator. You have to guard against that."
"But Dr. Suess," piped Broecker, "how do I do that?"
"Be a dynamic incompetent! Do at least three outrageous acts a year. Then no one will want you to be an administrator."

Wallace Broecker and Robert Kunzig, "CO2 - Fixing Climate", chapter "Carbon dioxide and the Keeling curve".

I'll have to remember that one for the rest of my career!...

The deepest joy of science

"Broecker likes figuring things out. He likes, above all else, putting a new piece in the puzzle. That is the best fun, the deepest joy.
Science is a system, a way of thinking and acting, and a community that allows you to taste that joy, on your luckiest days. It is the belief that if we observe the world carefully, test our ideas skeptically, and communicate honestly, we can figure things out."

Wallace Broecker and Robert Kunzig, "CO2 - Fixing Climate", chapter "Finding Science".

This reminds me of my mother telling me I loved and was very good at puzzles at an early age. This is undoubtedly what I like most in my job, having to figure out how the ocean works from observations I collect about it.

The future

I think this one is originally from somebody else, but I read it again in this book anyway:

"The future cannot be forecast, but it can be explored."

E. F. Schumacher, Small is beautiful.

See also this related and much more developed post from my friend François.

Simplicity again

"It is my experience that it is rather more difficult to recapture directness and simplicity than to advance in the direction of ever more sophistication and complexity. Any third-rate engineer or researcher can increase complexity; but it takes a certain flair of real insight to make things simple again."

E. F. Schumacher, Small is beautiful.

See also this post.

From a scientific perspective, I like this viewpoint, and I am always trying to understand what I observe with some explanatory mechanisms based on simple principles. But I am aware that it is also dangerous to go too far in this direction, and that the simple theoretical principles are most often valid only under strong assumptions that are never satisfied in reality, so that their explanatory power is questionable and the possibility that what I observed was the result of something else must at least remain open.

From a philosophical perspective, I dislike this viewpoint, which would lead to a meaningless world where everything is deterministic and we are just complex machines without souls. I prefer the holistic philosophies of people like Ram Dass and Eckhart Tolle.

R & D financing

"When R & D* is aimed mainly for general scientific knowledge, the needs of the poor, the global commons, or rapid social uptake, public financing is advantageous compared with reliance on patents. When R & D is targeted mainly for the rich or private use or gradual uptake, the patent-based incentives are relatively advantageous. In general, a healthy innovation system will use a mix of public financing and patents. For global sustainable development, the mix of public financing and private incentives should be harmonized globally to ensure that the needs of the poor and the global commons are properly addressed and financed by shared contributions of the world's governments."

Jeffrey Sachs, Common Wealth, Economics for a crowded planet, chapter "Our crowded planet".

* Research and Development

Economics needs a scientific revolution

Today, I read in last week's issue of Nature an excellent short essay about economics science, written by Jean-Philippe Bouchaud, head of research of Capital Fund Management and a physics professor at École Polytechnique in France. Extracts :

"Compared with physics, it seems fair to say that the quantitative success of the economic sciences has been disappointing. Rockets fly to the Moon; energy is extracted from minute changes of atomic mass. What is the flagship achievement of economics? Only its recurrent inability to predict and avert crises, including the current worldwide credit crunch.

Why is this so? Of course, to paraphrase Isaac Newton, modelling the madness of people is more difficult than modelling the motion of planets. But statistical regularities should emerge in the behaviour of large populations, just as the law of ideal gases emerges from the chaotic motion of individual molecules. To me, the crucial difference between modelling in physics and in economics lies rather in how the fields treat the relative role of concepts, equations and empirical data.

Classical economics is built on very strong assumptions that quickly become axioms: the rationality of economic agents (the premise that every economic agent, be that a person or a company, acts to maximize his profits), the 'invisible hand' (that agents, in the pursuit of their own profit, are led to do what is best for society as a whole) and market efficiency (that market prices faithfully reflect all known information about assets), for example. An economist once told me, to my bewilderment: "These concepts are so strong that they supersede any empirical observation." As economist Robert Nelson argued in his book, Economics as Religion (Pennsylvania State Univ. Press, 2002), the marketplace has been deified.

Physicists, on the other hand, have learned to be suspicious of axioms. If empirical observation is incompatible with a model, the model must be trashed or amended, even if it is conceptually beautiful or mathematically convenient. So many accepted ideas have been proven wrong in the history of physics that physicists have grown to be critical and queasy about their own models. [...]

The supposed omniscience and perfect efficacy of a free market stems from economic work done in the 1950s and 1960s, which with hindsight looks more like propaganda against communism than plausible science. In reality, markets are not efficient, humans tend to be over-focused in the short-term and blind in the long-term, and errors get amplified, ultimately leading to collective irrationality, panic and crashes. Free markets are wild markets. [...]

Surprisingly, classical economics has no framework through which to understand 'wild' markets, even though their existence is so obvious to the layman. Physics, on the other hand, has developed several models that explain how small perturbations can lead to wild effects. The theory of complexity shows that although a system may have an optimum state, it is sometimes so hard to identify that the system never settles there. This optimum state is not only elusive, it is also hyper-fragile to small changes in the environment, and therefore often irrelevant to understanding what is going on. There are good reasons to believe that this paradigm should apply to economic systems in general and financial markets in particular. We need to break away from classical economics and develop completely different tools. Some behavioural economists and econo-physicists are attempting to do this now, in a patchy way, but their fringe endeavour is not taken seriously by mainstream economics.

While work is done to enhance models, regulation also needs to improve. Innovations in financial products should be scrutinized, crash-tested against extreme scenarios outside the realm of current models and approved by independent agencies, just as we have done with other potentially lethal industries (chemical, pharmaceutical, aerospace, nuclear energy).

Crucially, the mindset of those working in economics and financial engineering needs to change. Economics curricula need to include more natural science. The prerequisites for more stability in the long run are the development of a more pragmatic and realistic representation of what is going on in financial markets, and to focus on data, which should always supersede perfect equations and aesthetic axioms."

Anti-dogmatisme

"Je n'ai pas la prétention de considérer [mes] expériences comme un modèle de perfection. Mon attitude à leur égard est, ni plus ni moins, celle d'un savant: en dépit de toute la minutie qu'il apporte à ses expériences et quel que soit leur degré de préparation et de précision, il n'accorde jamais de valeur définitive aux conclusions qu'il en tire, mais se tient prêt au contraire à les remettre en question."

Mohandas Gandhi, Tous les hommes sont frères, chapitre "En guise d'autobiographie".

For the beauty of science

"But we must not forget that when radium was discovered no one knew that it would prove useful in hospitals. The work was one of pure science. And this is a proof that scientific work must not be considered from the point of view of the direct usefulness of it. It must be done for itself, for the beauty of science, and then there is always the chance that a scientific discovery may become like the radium a benefit for humanity."

Marie Curie, "On the discovery of radium", speech delivered in 1921.

We should always keep this in mind, and resist the spreading of the capitalist logic into the realm of research, as is being done for example right now in France to the Centre National de la Recherche Scientifique (CNRS) with the recently created Agence Nationale de la Recherche (ANR).

Recherche et réciprocité

Un argument fondamental contre la direction que le gouvernement français actuel veut donner à la recherche (à savoir diminuer la recherche fondamentale financée par les fonds publiques au profit de la recherche appliquée financée par les entreprises):

"Depuis 1980, date où General Electric réussit à faire breveter un gène, les firmes américaines peuvent breveter le vivant. Depuis, des milliers de gènes sont brevetés, comme ceux prédisposant au cancer du sein. Du coup, les laboratoires rivaux travaillant sur le cancer du sein ne peuvent plus faire d'expérimentation sur ces gènes. La recherche sur le cancer du sein est fortement pénalisée. Certes, la firme ayant déposé le brevet peut arguer du fait qu'elle a dans son équipe le petit génie qui va guérir le cancer du sein. Mais c'est méconnaître une loi fondamentale de la recherche: la masse et la réciprocité.
Pourquoi la Chine fit-elle toutes les découvertes importantes de l'Humanité avant la révolution industrielle ? Parce qu'elle était le pays le plus peuplé du monde, le pays où les apprentissages, les itérations, les erreurs répétées et corrigées et les découvertes étaient plus fréquents qu'ailleurs. De même, pourquoi y eut-il tant de chercheurs géniaux autour d'Einstein (Gamow, Pauli, Schröedinger...) ? Parce que celui-ci ne protégeait pas ses découvertes comme un avare sa cassette. Et pourtant, Einstein savait parfaitement ce qu'était un brevet: il travaillait à l'Office des brevets de Berne et déposa des brevets à titre personnel. Mais ce n'est qu'en communiquant avec les autres chercheurs qu'il avança, et que ceux-ci progressèrent. La science est quelque chose de trop sérieux pour la laisser aux entreprises, guidées par la seule loi du profit à court terme. La recherche n'avance pas de manière masquée. Elle ignore le concept de propriété. Einstein ne s'est jamais cru le propriétaire de ses équations, ni même, modestement, leur inventeur. Il savait qu'il devait trop à ceux qui cherchaient en même temps que lui.*"

* Un chercheur, le docteur Marra, a réussi à séquencer le génome du virus du Sras, laissant espérer un traitement et, pourquoi pas, un vaccin contre cette maladie. Aussitôt, la firme pour laquelle il travaillait a déposé un brevet. Le docteur Marra a refusé d'associer son nom au brevet, arguant de ce que les séquences d'ADN sont des découvertes, et non des inventions et, en ce sens, non brevetables. Chapeau, docteur Marra !

Bernard Maris, dans l'Antimanuel d'économie. 2. Les cigales, chapitre "La revanche de la coopération" (note ajoutée de l'auteur, accentuation en gras personnelle).