The New Physics and Its Evolution | Page 8

suddenly strip the last veils from nature, and to divine her supreme

secrets; but they work prudently and advance but slowly, while on the
ground thus conquered foot by foot they endeavour to establish
themselves firmly. They study the various magnitudes directly
accessible to their observation without busying themselves as to their
essence. They measure quantities of heat and of temperature,
differences of potential, currents, and magnetic fields; and then,
varying the conditions, apply the rules of experimental method, and
discover between these magnitudes mutual relations, while they thus
succeed in enunciating laws which translate and sum up their labours.
These empirical laws, however, themselves bring about by induction
the promulgation of more general laws, which are termed principles.
These principles are originally only the results of experiments, and
experiment allows them besides to be checked, and their more or less
high degree of generality to be verified. When they have been thus
definitely established, they may serve as fresh starting-points, and, by
deduction, lead to very varied discoveries.
The principles which govern physical science are few in number, and
their very general form gives them a philosophical appearance, while
we cannot long resist the temptation of regarding them as metaphysical
dogmas. It thus happens that the least bold physicists, those who have
wanted to show themselves the most reserved, are themselves led to
forget the experimental character of the laws they have propounded,
and to see in them imperious beings whose authority, placed above all
verification, can no longer be discussed.
Others, on the contrary, carry prudence to the extent of timidity. They
desire to grievously limit the field of scientific investigation, and they
assign to science a too restricted domain. They content themselves with
representing phenomena by equations, and think that they ought to
submit to calculation magnitudes experimentally determined, without
asking themselves whether these calculations retain a physical meaning.
They are thus led to reconstruct a physics in which there again appears
the idea of quality, understood, of course, not in the scholastic sense,
since from this quality we can argue with some precision by
representing it under numerical symbols, but still constituting an

element of differentiation and of heterogeneity.
Notwithstanding the errors they may lead to if carried to excess, both
these doctrines render, as a whole, most important service. It is no bad
thing that these contradictory tendencies should subsist, for this variety
in the conception of phenomena gives to actual science a character of
intense life and of veritable youth, capable of impassioned efforts
towards the truth. Spectators who see such moving and varied pictures
passing before them, experience the feeling that there no longer exist
systems fixed in an immobility which seems that of death. They feel
that nothing is unchangeable; that ceaseless transformations are taking
place before their eyes; and that this continuous evolution and perpetual
change are the necessary conditions of progress.
A great number of seekers, moreover, show themselves on their own
account perfectly eclectic. They adopt, according to their needs, such or
such a manner of looking at nature, and do not hesitate to utilize very
different images when they appear to them useful and convenient. And,
without doubt, they are not wrong, since these images are only symbols
convenient for language. They allow facts to be grouped and associated,
but only present a fairly distant resemblance with the objective reality.
Hence it is not forbidden to multiply and to modify them according to
circumstances. The really essential thing is to have, as a guide through
the unknown, a map which certainly does not claim to represent all the
aspects of nature, but which, having been drawn up according to
predetermined rules, allows us to follow an ascertained road in the
eternal journey towards the truth.
Among the provisional theories which are thus willingly constructed by
scholars on their journey, like edifices hastily run up to receive an
unforeseen harvest, some still appear very bold and very singular.
Abandoning the search after mechanical models for all electrical
phenomena, certain physicists reverse, so to speak, the conditions of
the problem, and ask themselves whether, instead of giving a
mechanical interpretation to electricity, they may not, on the contrary,
give an electrical interpretation to the phenomena of matter and motion,
and thus merge mechanics itself in electricity. One thus sees dawning

afresh the eternal hope of co-ordinating all natural phenomena in one
grandiose and imposing synthesis. Whatever may be the fate reserved
for such attempts, they deserve attention in the highest degree; and it is
desirable to examine them carefully if we wish to have an exact idea of
the tendencies of modern physics.

CHAPTER II
MEASUREMENTS
§ 1. METROLOGY
Not so very long ago, the scholar was often content with qualitative
observations. Many phenomena were studied without much trouble
being taken to