Physics and Philosophy: The Revolution in Modern Science Paperback – May 8, 2007

On my personal journey reading 'classical' books from the past I have recently read Heisenberg's 'Physics and Philosophy' , originally published 1958. More than 50 years later this seems to be still a very remarkable book, with an easy reading and a scope of thinking which is rare today.PHYSICSHeisenberg describes in his book the modern findings in physics in a language which does not presuppose any mathematics. And he describes these central findings in a way which is even clearer than written in the complex mathematical machinery of modern physics. The detection of the atomic structure of matter, the discrete structure of the energy levels, the velocity of light as the upper limit of the velocity of all moving bodies, the uncertainty in the description of the behavior of the atomic elements caused by the inevitable interaction between observer and observed object, the equivalence of matter and energy as well as the new structure of the physical space (non-euclidean) compared to the space of our perceptions, imaginations and the everyday space of daily actions. I can not remember any other book about physics which explains these developments in such a clearness and directness.PHILOSOPHYThe book gains even more because Heisenberg compares the concepts of the modern physics with the main concepts of the old Greek philosophy as well as with philosophers like Descartes, Locke, Hume, Berkeley, and Kant. It is interesting to see that human kind was more than 2000 years ago capable to develop conceptual models of matter and nature which logically come very close to the modern concepts of the atom and its parts. At the same time it is interesting to see, that despite of this astonishing conceptual thinking the lack of proper measurement instruments and the lack of a sufficient mathematical language didn't allow better theories. Thus the development of new measurement instruments, new strong languages like modern mathematics as well as the right experiments appear to play a fundamental role in the construction of better world models; they are not 'outside' of the story but a central moment of it.LANGUAGEHeisenberg describes in length the insufficiency of language to describe the new findings in physics, especially those headed under the label of quantum mechanics, not an insufficiency only of the everyday language, but also an insufficiency of the mathematical language as such. While the concrete experiments are described with everyday language expressions and the terms of classical physics do the mathematical expressions describe formal structures like probability fields which encode expectations about the behavior of the quanta which as such are not concrete objects. From the point of theory there is no complete consistent solution conceivable for this problem, only 'practically' by relating concrete experimental data with the abstract mathematical models.WELTBILD/ WORLD VIEWHeisenberg describes not only the development of modern physics but considers also the effect of this new world picture on the overall world view of mankind. He suggests that the physical world view before quantum theory was too narrow, not giving satisfying answers to central phenomena like biological life, the human mind or even the concept of human soul. Only quantum theory has -according to Heisenberg-- forced an opening of central concepts, has widened the concept of objectivity, has reinforced the awareness that the observer is a central moment of the observed object; there is no 'real objectivity'. Knowledge is always a construct under certain conditions where we have to 'extrapolate' the 'hidden' structures with some probability. With regard to biology he states explicitly "...we are obviously still very far from such a coherent and closed set of concepts for he description of biological phenomena. The degree of complication in biology is so discouraging that one can at present not imagine any set of concepts in which the connections could be so sharply defined that a mathematical representation could become possible". (PP79f)" If we go beyond biology and include psychology in the discussion then there can scarcely be any doubt but that the concepts of physics, chemistry, and evolution together will not be sufficient to describe the facts ..".(PP80)CRITICAL REMARKSIf one wants to find weak points in the wonderful book, one can mention some. There is nearly no citation; this makes it difficult to follow the sources (if one wants). The look to philosophy is very narrow; many modern developments have not been cited, especially not the large amount of work in semiotics, philosophy of language, and formal logic. He mentions the limits of mathematical theories without citing the famous results of Goedel (1931) and Turing (1936/7). Or, he mentions the logic of quanta proposed by Weizsäcker which has the format of a type logic; this has been introduced by Whitehead-Russel already in 19010ff. Heisenberg argues for the limits of physics with regard to biology using arguments which resemble those of Schroedinger in his famous book of 1944, without mentioning Schrödinger. Despite all this, for me this is a very remarkable book, extremely clear, and very inspiring.FUTUREThe book shows that central questions regarding man are not solved. The phenomenon of life is still the big challenge of science.

I will only mentioned a few aspects of the world of quantum mechanics and then if you get bored you can read the last part where I mention some aspects of the book.Werner Heisenberg is one of the most important figures within the world of quantum mechanics. Since Max Planck discovered that electromagnetic energy could be emmited in quantized forms a series of new discoveries revolutionised the world of physics. Albert Einstein confirmed Plancks's discoveries and theorized that light was composed of discrete quanta. This discovery was just too strange. How can light behave as a wave and as a particle. You can see the double slit experiment and observe how light behave when one slit is open and when the two slits are open, just amazing.So it seems that dualistic thought can not be applied here. Is light particle or wave, the answer: BOTH!As Heisenberg says in the book: "that what we observe is not nature in itself but nature exposed to our method of questioning". Thus observer and observed are in some way connected and not separated as in cartesian-newtonian world.In the introduction is written clearly: "...the act of of measurement defines the thing being measured, or that the thing being measured and the thimg doing the measuring are inextricably interwined"This is why there have been some analogies between this new physics and eastern traditions (like Fritjof Capra's Tao of Physics)like buddhism and the Indian philosopher Nagarjuna, founder of the Madhamyaka school that developed the concept of emptyness, that is, all phenomenon had no "self-nature" "or idependent origins", there is no such thing as Parmenide's Being.All is interconnected,like Indra's jewels in Hinduism there is no gap between the observer and the observed in the world of quantum physics. Quantum mechanics is more familiar with Heraclitus where Change is the main principle, Becoming and not Being.Particles are not "things" but are like Aristotle's potentia. Heisenberg tell us: "A quantum object, in itself, is neither one thing not the other. If you decide to measure a wave-like property, the thing you are observing will look like a wave. Measure a particle property (position or velocity), on the other hand, and you will see particle-like behaviour." Note that Heisenberg that one can measure position OR velocity, this is the pillar of the uncertainty principle. In Heisenberg's words: 2The better you measure the position of a particle, the less you can find out its velocity, and vice versa."Thus, the first years of the 1920s was a turning point in the world of physics. The Copenhagen Interpretation established the principles of quantum mechanics, some of this are: The uncertainty principle, the Complementary Principle (wave-particle duality of light) and that the description of nature is probabilistic.Now you can have a little clue about the book subtitle: "The revolution in modern science". Newtonian mechanics can' t be applied to the subatomic world.Thus, the view of nature as a Big, impersonal Machine and that it was a matter of time that "all mighty rational humanity" was to discover all its laws is far from true. Even Einstein was not happy with this group of physicians that were saying "there is no such thing called objectivity" "newtonian laws are like a fish in the desert". Einstein after the theory of special and general relativity spent much of his time lookink for a Theory of Everything (TOE), and in some isolated himself from this great discoveries being made in the field of quantum mechanics.Today there is this String Theory or M Theory wandering arround, and could be the best candidate that will unify the 4 forces: Gravity, electromagnetism, strong and weak interaction. Time will tell...About the book:Heisenberg explains the developmet pf pshysics reviewing Thales, Anaximander, Anaximenes (the three Milesians)Heraclitus, Parmenides, Empedocles, Anaxagoras, Democritus, Leucippus, then a quntum leap to Descartes and Kant.He explains relativity, space, time, the Copenhagen Interpretation, the limits of language to describe the quantum world, the role of scientists, his Nobel Lecture and much more.I think it is not a difficult book, but don't expect to understand quantum mechanics, because if you do, you really didn't understand a thing about it. So forget about binary-aristotelic logic and start developing fuzzy logics to understand a lot of weird things.