I would like to respond to these infuriating texts.
Smolin's quotes will be blockquoted upon the blue background:
Dear Peter, Krauss’s hostility to philosophy is hardly new, it is the perspective within which our generation of physicists was educated. It is the defining polemic of a tradition of pragmatically oriented theoretical physicists whose dominance began with the generation of Feynman and Dyson. They took over leadership of science from the previous generation, who were heavily influenced by, and respectful of the tradition of philosophy, led by Einstein, Poincare, Bohr etc. The transition was marked by Dyson who noted that he was part of a generation of young conservatives who took over from a generation of old revolutionaries, who were seen as having exhausted themselves on fruitless philosophical quests such as the interpretation of quantum theory.One of the reasons why Smolin completely misunderstands physics is that much like Leon Trotsky, he is obsessed with the permanent revolutions. Whether we call someone a revolutionary usually depends on his or her comparison with the prevailing culture of his or her time and his or her comparison with the previous beliefs and habits.
However, these comparisons are purely sociological in character; they have no impact on the actual scientific results. Two people may be saying or finding the very same things and depending on their environments, they may be considered both revolutionaries or conservatives. These differences only tell us something about the societies, not about the science.
From a scientific viewpoint, the reality is that there has never been any qualitative difference between the generations that Smolin tries to put against each other. In fact, despite the misconceptions believed by the laymen including Smolin, not even Einstein considered himself a revolutionary who wanted to negate the work of Isaac Newton and others. Instead, Einstein considered relativity to be an improvement or clarification of Newton's and Maxwell's theories and he has explicitly stated this point of view several times.
On the other hand, it is true that Einstein has obviously brought new important ideas to physics, including new philosophical principles how the truth should be searched for. In particular, he realized that certain seemingly objective quantities or properties – such as the simultaneity of two events – don't have to be objective or don't have to "exist". He was the first one to fully realize that physics is only obliged to discuss properties of Nature that can actually be operationally measured, at least in principle. The simultaneity of two events and other things that became "relative" in the theory of relativity can't be established by objective operational tests so they may be subjective. Einstein was the first major practitioner of positivism in physics.
I have already mentioned that Werner Heisenberg in particular considered quantum mechanics to be a continuation of the new Einsteinian positivist line of reasoning. Much like the simultaneity of two events may be subjective, all other data describing the reality may be subjective as well. That's why it should be natural for a 20th century physicist to understand that the world is described by a wave function (or a density matrix) that must be interpreted as a set of complex numbers summarizing a subjective knowledge about the real world. In practice, people will agree about many things so that the "objective flavor" of the macroscopic world will be restored but at the fundamental level, the wave functions are subjective constructs. Our physical theories don't have to say how the world "is" prior to the measurement because this question can't be operationally answered, not even in principle. And indeed, the right theory – quantum mechanics – says that the world doesn't have any sharp well-defined properties prior to the measurement.
Einstein never accepted quantum mechanics but he was still essential for its birth. His contributions were not only technical in character – I mean his discovery of the light quanta in the photoelectric effect or the Bose-Einstein statistics, among other things. He also created the appropriate positivist atmosphere that made it easier for Heisenberg and others to think in the new ways.
So the gap between Einstein and the founding fathers of quantum mechanics – physicists who were mostly 20 years younger than Einstein – wasn't complete. They agreed about most things, including the majority of questions about (then) new physics. But the gap between the founding fathers – people whom Smolin calls revolutionaries – and the generation that was younger by additional 20 years – Smolin's conservatives (Feynman, Dyson, and others) – was even smaller. They really believed the same things about the early 20th century science and its philosophy – about topics such as relativity and the (proper Copenhagen-like) quantum mechanics. The only difference was that the younger generation had 20 more years of hindsight so it took certain insights that were found when this new generation was in the kindergarten for granted. These well-established insights were already hardwired into the younger physicists' brains. It can't be otherwise. The newer generation builds on foundations that were shaky just decades ago and it investigates more detailed questions that the previous generations were often unable even to ask.
It works for every generation because every generation is really building on the shoulders of the previous generations. The very Smolin's idea that the progress in physics is about a largely symmetric intergenerational fight between conservatives and revolutionaries (that is probably supposed to go back and forth) is a deep misunderstanding of the whole institution of science and its history. Science has never worked in this way. One can only do proper science – one may belong to the sequence of people such as Newton, Maxwell, Einstein, Bohr, Heisenberg, Feynman, Dysons, and their more or (usually) less famous colleagues – or one may fail to belong to this sequence – be a Lee Smolin, for example. Demagogic arguments about non-existing reversals of science can't turn a non-scientist to a scientist.
The triumph of that generation was quantum field theory and it is certainly ironic that the exhaustion of their pragmatic style is marked by the over-extension of quantum field theory to address questions it can’t possibly answer such as the origin of the universe. Only someone whose understanding of the world comes entirely from within the pragmatic tradition could imagine that the description of a phase transition from one quantum field theoretic vacuum to another-both existing in a background spacetime-addresses the metaphysical-and probably unsolvable-question of why something exists rather than nothing.First of all, it is breathtakingly untrue and stupid to suggest that the "pragmatic style" of physics has been "exhausted". The pragmatic style has been adopted by physics approximately 100 years ago and it has never been abandoned. It was the underlying philosophy beneath pretty much all discoveries in physics in the last 100 years. One (I mean Smolin) may constantly spit on the whole fascinating 20th century and early 21st century progress in science – but by such spitting, one only proves his complete inadequacy as a scientist.
The "pragmatic style" may include behavioral patterns and intonations – and those things may surely change. But it also includes certain essential philosophical attitudes whose importance has been learned and it can never be unlearned again. The importance of being able to describe operational consequences of a hypothetical concept – and the unimportance of vague "philosophical" words in physics – belong among these principles that all actual scientists have learned to appreciate.
Physicists have learned that the colloquial everyday language may be loaded and misleading – and careful mathematical claims about in-principle observable quantities are needed instead – and they will never unlearn it.
Completely off-topic, appropriate for the ongoing Central European early summer: Ms Heidi Janků, "When I put makeup on my face", 1986 (yes, this mainstream song from the late socialist era is more capitalist-commercial-hip than many Western songs today, isn't it?). Video with Demi Moore; see the fairy-tale original version.
Certain questions relevant for the birth and early evolution of the Universe may require full-fledged quantum-gravitational i.e. string-theoretical insights and mechanisms; but some questions are independent of them and may be addressed within an effective quantum field theory. To say the least, effective quantum field theories will keep on playing a vital role in any sensible research of fundamental physics, including the research of early cosmology and whether their relative importance will increase or decrease is yet to be seen. Within physics as we know it, Smolin's dismissive comments about quantum field theory are indefensible.
It's kind of amazing that a person who hates quantum field theory (and its legitimate ramifications) so much could have gotten a physics degree at Harvard – moreover in years when Sidney Coleman dominated the teaching of quantum field theory at that university.
And sadly, among the things you throw out when you discard philosophy is the work of Popper and others who established the demarcation between science and metaphysical nonsense.The reason why physicists discard Popper's work is that it is not science. It is a philosophical ideology that hasn't passed the tests that scientific hypotheses have to pass in order to be established. Scientists have the right to investigate whatever they want and in principle, every aspect of observable reality is accessible to the scientific method. In some cases, the research succeeds, in others, it doesn't, but topics can't be "banned for scientific research" a priori.
Whether a topic lies in front of or behind an ad hoc demarcation line invented by a random philosopher – and mindlessly parroted by his blinded brainwashed followers – plays absolutely no role. Popper has understood certain things about science (i.e. that it talks about questions that are ultimately linked to empirical observations and that admit at least two a priori conceivable, operationally distinguishable answers) and misunderstood many others (he misunderstood that it's not necessary for things to be testable directly; he misunderstood that science can and has to introduce many auxiliary concepts that are not directly observable; he misunderstood that the confirmation and refutation of a hypothesis are largely "symmetric" procedures, and so on). It's certainly preposterous to refer to Popper as the guy who should be restricting the ways in which science may expand in centuries after his death. He didn't quite understand even science of his own time; and he surely had no idea about the conceptual progress and transformations that science has made decades after his death.
I believe that the pendulum is swinging back because many of us have learned that an engagement with philosophy does greatly aid a serious assault on the key questions physics faces such as quantum gravity, the foundations of quantum theory and questions as to the choice of laws and cosmological initial conditions. Krauss wouldn’t know it because he hangs out in the wrong circles, but there is a healthy dialogue between physicists and philosophers about these issues, which has greatly stimulated both sides. This engagement has been fruitful to a large extent because of a new generation of philosophers, such as David Albert, who are very well educated in physics. And as we see from Albert’s review, they can certainly hold up their side of a debate because they understand contemporary physics far better than Krauss understands contemporary philosophy.Lee Smolin or some random philosophers may believe any superstition about pendulums he or they want but science isn't about beliefs. Science is about rationally justifiable propositions that may be shown to boil down to empirically observable facts plus mathematics (and logic). And when one looks at the actual science relevant for the questions about the origins, it is clearer than ever that philosophy – in the sense of non-mathematical would-be wise talking (often building on the "authorities" and other sociological theaters rather than arguments) that is detached both from the meticulous mathematical formalism as well as from the operational, pragmatic, positivist style of physics – has continued to diverge from physics as a natural science and there are good reasons to think that this divergence is bound to continue. As the physical image of Nature is getting more complete, more far-reaching, and therefore more abstract, it is increasingly impossible to properly understand what's going on without getting familiar with the physical toolkit that actually has an explanation for all the phenomena and patterns we know in Nature. Philosophy building on words and preconceptions is increasingly inadequate. A philosopher's understanding of physics is too superficial for him to say something sensible about the cutting-edge physics research.
It is also disturbing to see that this fake issue is taken as somehow proxy for the conflict between science and religion. For one thing, it is hardly the case that Albert or other contemporary philosophers of physics defend the claims of religion or the medieval arguments about the why something rather than nothing query. Quite the opposite, they tend to employ the same piercing logic Albert used to puncture Krauss’s arguments to destroy the claims of theologians and metaphysicians. Among the several ironies of this story is that the people Krauss is attacking are able to more powerful arguments against the claims of religion because they have a sophisticated education in the history of science and philosophy. To see how effectively a philosophically sophisticated physicist with a good classical education can make a case against religion that goes far deeper than Krauss’s into the historical roots of the conflict with science, you might look at Carlo Rovelli’s The First Scientist: Anaximander and his Legacy.This is just another paragraph that shows how totally unscientific Smolin's reasoning is. Whether someone has a degree in the history science or philosophy (or whether someone loves to pay lip service to some philosophers) doesn't make his statements about the relationship between science and religion valid. Quite on the contrary, most people who only hold degrees in these social sciences don't really understand how science actually differs from religion (and in what respect it doesn't differ!) and which of the previously religious questions may be addressed by science and which of them can't and how they should be investigated if they can. One can't fake the actual understanding of these issues by some degrees from social sciences, humanities, or other inferior intellectual activities. To say the least, these folks have nothing legitimate to say about science, its particular propositions about Nature, its methodology, and its general principles and limitations.
Dear Peter [another Shmoit], I am normally a big fan of Krauss’s writing defending science and I should say I haven’t read the book. But if he said what Albert indicated he said then this time he over-reached.Science has higher standards for belief – relatively to religions, philosophies, or Lee Smolin – but this fact also makes the scientific "beliefs" that can be obtained by the scientific method more solid than the beliefs underlying religions, philosophies, and Lee Smolin's babbling. When your skyscraper stands on a firm ground and is constructed from a robust material and according to a stable enough project, you may safely walk on its 10th and sometimes even 100th floor.
The reason to prefer science to religion is not that science offers the better story to explain enigmas like why the world exists or consciousness. To the contrary, science offers nothing to compete with the certainties of religious dogmas on such questions. The reason is that science has a far higher standard for belief and this standard results in knowledge that is limited in scope and always provisional. But it is the best knowledge we can have, if by knowledge we mean provisional understanding that can be established and defended by rational argument from public evidence. Therefor it is a mistake to compete with religion on explaining how or why the universe began because it is a fight we can only contest by giving up the methodologies and standards to which we owe our entire success.
The primary purpose of science isn't to "compete with religion" but at least since Galileo Galilei, science isn't obliged to avoid questions previously discussed by theologians, either. In many cases, science does exactly this thing: it offers scientific theories for questions that were previously explained by religious theories, questions that religions wanted to have a monopoly in. Smolin pretty much suggests that science should avoid such topics because it would "compete with religion" which Smolin doesn't find kosher; it's not hard to see that Smolin's statement is exactly isomorphic to the opinions of the Catholic Inquisition in the Middle Ages. Smolin is the kind of guy who will scream at you "heretic!" is you start to investigate questions that he considers too dangerous for his own beliefs.
But the preconception of the medieval Catholic bigots or, equivalently, Lee Smolin is just wrong: there is absolutely no reason why science shouldn't offer better "competing theories" for questions that religion previously attempted to address. In fact, science has already done this thing in many situations. The mere fact that a religion had previously offered a religious answer to a question doesn't mean that science isn't able – or isn't allowed – to offer a robust, scientifically justified answer to this question! And the scientific answer may both resemble as well as differ from the previous religious answers.
Anna asks for examples of contributions from philosophy to progress in physics. Here are a few that come quickly to mind:One may talk about "inspirations" but what's important is that the final product of Einstein's thinking, the general theory of relativity, refutes Mach's principle (and certainly its Leibnizian foundations). Mach's principle may have inspired Albert Einstein to do several steps but it is equally true that its aspects that are wrong have slowed down Einstein's research – by as much as 10 years. It's just totally dishonest to cherry-pick the "positive inspiration" only. If Einstein were not misled by the Machian nonsense, he would probably think about the gravitational field as a field filling the vacuum that obeys some equations from the beginning. He would know that the field must be able to become "locally inertial" but it is not obliged to be "globally inertial" as Mach's principle demanded.
-Leibniz’s thinking on the need for space and time to be relational, a consequence of his principle of sufficient reason, inspired Mach to invent Mach’s principle, which in turn inspired Einstein in his invention of general relativity.
-’t Hoofts work on foundational problems in quantum theory led to his postulation of the holographic principle which led to AdS/CFT.It's complete bullshit. In 1993, when he proposed the early vague form of the holographic principle, 't Hooft wasn't working on any foundations of quantum mechanics and surely not on philosophy (in the sense used by people from the philosophy departments). He was working on quantum gravity and he had been obsessed by this topic pretty much from the late 1970s. And indeed, 't Hooft's guess that quantum gravity would become an important focal point of fundamental physics research within decades was spot on. He only started to write papers about deterministic misinterpretations of quantum mechanics in the recent 10 years or so and none of these papers has ever made any sense. None of these papers was crucial – and not even helpful – for the research of holography.
Moreover, it's also untrue that 't Hooft's paper led to the AdS/CFT correspondence. Maldacena's paper launching the AdS/CFT correspondence was a result of his work on black holes and black p-branes within string theory, a new branch of research that became possible due to the Second Superstring Revolution in the mid 1990s (an event that introduced dualities, branes, and M-theory, among other things). If 't Hooft and Susskind had never written their papers on the holographic principle, Maldacena would still have written the same paper about the equivalence of the gravitational bulk theory and the non-gravitational boundary theory. The actual history was such that Maldacena's construction provided us with a detailed realization of some speculations that had already appeared in the literature; however, it's not true that Maldacena obtained his detailed insights by "thinking deep" about those previous speculative papers. He was doing a much more specific technical work on a somewhat different topic.
The AdS/CFT was a culmination of a very specific revolution in string theory, a revolution that followed all the rules of proper quantum theory, "conservative science" dominated by a careful interplay of meticulous equations, and that exhibited the same "pragmatic style" that Smolin hates so much. There was absolutely no "philosophy" – surely not philosophy of the kind that is done by "professional philosophers" – that led to the AdS/CFT correspondence.
-Turing and Godel’s work on foundations of mathematics and logic directly inspired von Neumann and his colleagues in his invention of the standard architecture of computers. (as detailed in George Dyson’s recent book.)I have never heard of that – and I really don't know how the former ideas could be useful for the latter – but even if it's true, the von Neumann architecture is really engineering, not science. There may have been interesting interactions between various people but what is really important is that an interaction between two people doesn't justify the claims of the person #1 (a philosopher) as soon as the results of the person #2 (a scientist or a mathematician in this case). "A helped to inspire B" (and even this situation is rare) does not imply "B's discovery justified the propositions by A". Even if you inspire me, it doesn't mean that I must confess that you are right about something!
-David Deutch’s thoughts on foundational problems in mathematics led him to invent quantum computation. The field of quantum information remains a lively point of interchange among physicists, computer scientists, and philosophers.There has been no open fundamental question about quantum information for many, many decades. All philosophers and would-be physicists who continue to discuss these things as "conceptually open mysteries" are incompetent crackpots. Deutsch is spelled with an "s" before "ch", as the German word for "German" demands.
-Julian Barbour’s extensions of Leibniz’s and Mach’s critiques led him to a deeper understanding of the role of active diffeomorphisms as the gauge symmetry of general relativity. This was a formative influence on the invention of background independent models of quantum gravity including loop quantum gravity. This also led him and younger colleagues to a reformulation of general relativity called shape dynamics, which in turn appears to explain the AdS/CFT correspondence as a property of general relativity.The AdS/CFT correspondence isn't a property of (just) general relativity. General relativity is just a low-energy limit of the full theory, string/M-theory, and all the technical details about string/M-theory are actually needed for it to have a holographic dual. The holographic principle only exists in the quantum version of gravity, as the presence of Planck's constant in the Bekenstein-Hawking entropy-area law makes obvious.
All the other statements prove the "garbage in, garbage out" paradigm. None of these Leibniz-Machian lines of reasoning has ever led to a physically meaningful theory capable of describing anything in Nature and all people working on loop quantum gravities and similar delusions are idiots.
One of the key errors that Smolin is making is that he seems to assume that whoever is writing papers similar to his own is doing a valuable science. However, the correct assumption that could replace Smolin's incorrect assumption is somewhat different: everything that Smolin has written in his life is pure garbage and most people who write similar things are imbeciles, too.
Smolin's attributions are incredible, too. The realization that the diffeomorphisms should be treated as a gauge symmetry, on par with Yang-Mills symmetries, was already clear to Richard Feynman in the early 1960s. He constructed the Feynman rules for general relativity and even managed to add the Faddeev-Popov ghosts – before Faddeev and Popov did it and in the context of a "more difficult" theory. Attributing these ideas to a Julian Barbour because it's convenient for the promotion of Lee Smolin's pet crackpot theories is just painful.
-The best work on the many worlds interpretation of quantum theory is by philosophers of physics in Oxford, Simon Saunders, Hillary Greaves and David Wallace. I must say I am not convinced, for reasons best argued by David Albert, but they made a far better case for the cogency of the interpretation than had been given by physicists.As I have repeatedly proven on this blog, all this philosophical work on the "many-worlds interpretation" of quantum mechanics is garbage, too.
In all the situations discussed above, one could have drawn a pretty sharp line separating two sides of the physics research. But it wasn't a line between revolutionaries and conservatives; it was a line between legitimate physics researchers and untrustworthy pseudoscientists. The legitimate physics researchers are relying on some known truths from the past and use the scientific method with all its vital properties – mathematical accuracy, existence of operational definitions and tests in principle, positivist or "pragmatic" style – to find new truths or clarify, sharpen, or explain the older ones. The pseudoscientists are doing something else. Most of the time, they are supporting their vague, verbal, prejudiced, nonsensical garbage by references to their degrees and other people who can only boast similar "credentials" and their dogmas but not arguments and discoveries that actually make any sense from the scientific viewpoint. Many of them often love to invent insulting lies about the first group of actual scientists. Lee Smolin is the ultimate prototype of the second group of slanderous pseudoscientists.
Jg at the same blog has pointed out that Einstein's attitude to philosophers hasn't been as loving as Smolin tries to suggest. On page 2 of his 1922 "The Meaning of Relativity", Einstein writes:
...I am convinced that the philosophers have had a harmful effect upon the progress of scientific thinking in removing certain fundamental concepts from the domain of empiricism, where they are under our control, to the intangible heights of the a priori. For even if it should appear that the universe of ideas cannot be deduced from experience by logical means, but is, in a sense, a creation of the human mind, without which no science is possible, nevertheless this universe of ideas is just as little independent of the nature of our experiences as clothes are of the form of the human body...