Foundations

On Realism and Quantum Mechanics

G. Giuliani. Il Nuovo Cimento 122 B (2007), 267

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About Time

Even time does not exists of itself; but sense reads out of things what happened long ago, what presses now, and what shall follow after;
no man, we must admit, feels time itself, disjoined from motion and quiet repose of things.

Lucretius, De Rerum Natura, I, 459-463.

La Misura del Tempo: prospettiva storica, Paolo Mascheretti, in G. Giuliani (a cura di), Le grandezze fisiche e la loro misura, Pavia, 1998, 33-109.

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Table of Contents:

  • Introduction
  • The measure of time
  • Sundials: playing with shadows
  • Hourglasses and water-clocks
  • Mechanical clocks and their forerunners
  • Clocks on towers
  • Astronomical clocks on towers
  • Planetariums
  • The race for portable clocks
  • Seeking precision
  • Beyond the mechanical clock

Links:

A walk through the time by the National Institute of Standards and Technology

On Electromagnetic Induction

It is generally acknowledged that the theoretical treatment of electromagnetic induction phenomena presents some problems when part of the electrical circuit is moving. Some authors speak of exceptions to the flux rule, while others save the flux rule by ad hoc choices of the integration line over which the induced emf is calculated.

A general law for electromagnetic induction phenomena is derived by defining the induced emf as the integral over a closed loop of the Lorentz force acting on a unitary positive charge. The induced emf is the product of two independent phenomena: time variation of magnetic field and effects of magnetic field on moving charges. The flux rule is neither a causal nor a field law: it is a calculation rule that yields the correct result, but not always.

Waves and Particles

Conservation laws and laser cooling of atoms

This is an author-created, un-copyedited version of an article accepted for publication in European Journal of Physics. IOP Publishing Ltd is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The definitive publisher authenticated version is available online at 2015 Eur. J. Phys. 36 065008

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