Popular Scientific Lectures

Summary

Popular Scientific Lectures gathers fifteen lectures and addresses that the Austrian physicist Ernst Mach gave between the 1860s and 1897 to general audiences, learned societies and university gatherings. They were first collected in English, translated by Thomas J. McCormack for the Open Court Publishing Company of Chicago in 1894–95; the library text is the enlarged third edition of 1898, whose proofs Mach read himself. The early lectures are demonstrations. 'The Forms of Liquids' opens with Socrates as the father of scientific criticism and shows how oil drops in a liquid of equal density take spherical and other shapes of least surface. 'The Fibres of Corti' and 'On the Causes of Harmony' explain Helmholtz's theory that the inner ear analyses sound into partial tones. 'The Velocity of Light' tells how Römer and Fizeau measured it. 'Why Has Man Two Eyes?' treats binocular vision and the stereoscope, and 'On Symmetry' asks why mirror symmetry pleases the eye. The middle group is historical and philosophical. A lecture on electrostatics (Vienna, 1883) defines its concepts by measurement; the long essay on the conservation of energy argues that the principle grew from the old conviction that perpetual motion is impossible. 'The Economical Nature of Physical Inquiry' (1882) gives Mach's best-known thesis: science is the economical ordering of experience, a way of saving thought by compact description, and concepts such as cause, force and the atom are tools for representing phenomena rather than realities behind them. 'On Transformation and Adaptation in Scientific Thought' (Prague, 1883) applies Darwin's idea of adaptation to ideas, which adjust to facts and to one another, and describes how scientists and others 'experiment in their thoughts'. Later addresses compare analogies in physics, weigh the part of accident in invention while insisting the inventor must notice and use what chance reveals, and report Mach's experiments on the sense of rotation, in which he spun himself on an apparatus and modelled the semicircular canals of the ear. 'On Some Phenomena Attending the Flight of Projectiles' (1897) describes his spark photographs of the shock wave around a bullet moving faster than sound. The final address, given at Dortmund in 1886, weighs instruction in Latin and Greek against mathematics and science, granting the classics real value but urging less systematic cramming and more science. Two appendixes treat the history of acoustics and spatial vision. Einstein later credited Mach's criticism of absolute space with helping prepare the way for general relativity.

Top Lessons

• Science as economy of thought

  Mach holds that a law of nature compresses many observations into one rule, so that what seems like sorcery is really good housekeeping of experience. The view explains the power of mathematics and also its limits, since every description sacrifices some completeness to usefulness.

• Ideas grow and adapt

  Writing after Darwin, Mach treats concepts as adapting to new facts and to one another. Wonder arises when a fact does not fit our habits of thought; understanding comes when thought adjusts. Experimenting in thought, which Mach finds in historians and artists as well as physicists, is the mind rehearsing such adjustments.

• Chance favours the attentive

  Mach gathers many examples of discoveries made by accident, yet he insists that the inventor must notice the new fact, grasp its use and turn it to account. Accident supplies opportunity, but attention, preparation and judgment supply discovery.

• Criticism of one's own concepts

  Mach begins the collection with Socrates' questions and repeatedly asks scientists to examine the origins of their concepts, lest a useful idea become an obstacle. His critique of atoms and absolute space was itself much debated: Boltzmann defended atoms, and the atomic hypothesis was soon strongly confirmed, while Einstein found Mach's criticism of absolute space fruitful.

Verified Quotes

Medical Lens

Several lectures belong to the history of sensory physiology. 'The Fibres of Corti' presents Helmholtz's resonance theory of hearing, in which structures of the cochlea respond to different pitches; Mach notes in a footnote that later work modified it. 'Why Has Man Two Eyes?' explains stereoscopic depth from the disparity between retinal images. 'On Sensations of Orientation' reports Mach's own experiments in the 1870s on a rotating chair, the illusions of rotation and inclination, and a mechanical model of the semicircular canals; Mach, Josef Breuer and Alexander Crum Brown reached the hydrodynamic theory of the vestibular organ independently, and Breuer later co-wrote Studies on Hysteria with Freud. Mach's broader claim that physics and psychology study the same elements of sensation from different sides influenced early psychology and the philosophy of mind. The projectile lecture, which opens with the irony of nations both inflicting gunshot wounds and trying to keep them small, concerns ballistics more than wound medicine. Mach also rejects Lombroso's view that genius is a disease.

• The Fibres of Corti

  Helmholtz's account of the cochlea as a set of resonators analysing sound, with the illustration of a deaf person 'hearing' through a piano.

• On Sensations of Orientation

  Self-experiments on a rotating apparatus, a disc model of the semicircular canals, and credit to Goltz, Breuer and Crum Brown for the theory of the sense of balance.

• The Part Played by Accident in Invention and Discovery, near the end

  Mach declines Lombroso's view that genius is a disease while noting that sensitive constitutions succumb readily to illness.

• On Some Phenomena Attending the Flight of Projectiles, opening

  Ironic opening on the duty both to inflict bullet wounds and to make and stop them as small as possible, before the physics of supersonic flight.