söndag 14 oktober 2012

From Pessimism to Positivism in Aerodynamics/Science



The Enigma of the Aerofoil: Rival Theories in Aerodynamics 1909-1930, by David Bloor, 2011, describes the initial British criticism of the German circulation theory of lift developed by Kutta and Prandtl in the beginning of the 20th century, which resisted the attack in the absence of something better and became the leading theory propagated in text books still today (see previous post).

The book can be read as an expression of the pessimism of science resulting from the collapse of classical rational science caused by certain apparent contradictions or paradoxes at the turn to the 20th century, which forced physicists to abandon causality/determinism and fundamental concepts of space and time in the formation of the modern physics of quantum mechanics and relativity theory. For perspectives on this astounding story check out Dr Faustus of Modern Physics.  

Bloor describes a similar collapse in aerodynamics away from the British rationality of the (Navier)-Stokes equations, because the equations could not be solved analytically and not computationally 100 years ago,  into a German "practical engineering solution" with lift trivially generated by circulation without description of the generation of circulation.

In the last chapter Pessimism, Positivism and Relativism: Aerodynamic Knowledge in Context, Bloor seeks to rationalize the drift away from positivism or "truth" into relativism with many truths or pessimism with no truth at all, as an inevitable process characterizing modernity:
  • Those who point to the airplane as a symbol of the truth of science, the power of technology, and the reality of knowledge are therefore right—but do they know what they are saying?
  • The successful strategy involved the deliberate use of known falsehoods in artful balance with accepted truths. The supporters of circulation theory showed how simple falsehoods could yield dependable conclusions when dealing with a complex and otherwise intractable reality. This is the real enigma of the aerofoil.
  • The enigma of the aerofoil is the enigma of all knowledge.
This expresses a breakdown of rational science into black magic, where simple falsehoods could yield dependable conclusions.

But today it is possible to solve the Navier-Stokes equations computationally, and this changes the science of aerodynamics from pessimism back into positivism and "truth", based on the original seemingly correct fundamental idea that all of fluid dynamics emerges as solutions of the Navier-Stokes equations. This brings a major change into aerodynamics as evidenced on The Secret of Flight, which may be representative for other areas of physics, as further elaborated on The World as Computation.

PS The philosophy of science reacts to the development of science with a certain delay. The logical positivism of the 1920s may be seen as an expression of classical rational science at its peak in the late 19th century, while the postmodern relativism and pessimism of e.g. Feyerabend in Against Method, expresses the collapse of rationality in modern physics.

An attempt to combine relativism with rational positivism is made in Many-Minds Relativity and Many-Minds Quantum Mechanics. I argue that relativism with different views of different observers who do not share a common "objective" view, is compatible with rational logical positivism.

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