[17] See note, p. 119.
[18] Since the above was written there has certainly been a great
change, and the dogmatic confidence in the verity of the scientific
"laws" has now (1920) almost disappeared.
[19] Such fictions, however, are (I need not say) quite necessary as our
only means of thinking out, however imperfectly, the problems before us
(1920).
[20] It is not generally realised how feeble a force gravitation is. It
is calculated (Encycl. Brit., Art. Gravitation) that two masses, each
weighing 415,000 tons, and placed a mile apart, would exert on each
other an attractive force of only one pound. If one, therefore, was as
far from the other as the moon is from the earth, their attraction would
only amount to 1/57,600,000,000th of a pound. This is a small force to
govern the movement of a body weighing 415,000 tons! and it is easy to
see that a slight variation in the law of the force might for a long
period pass undetected, though in the course of hundreds of centuries it
might become of the greatest importance.
[21] As another instance of the same thing, let me quote a passage from
Maxwell's _Theory of Heat_, p. 31; the italics are mine: "In our
description of the physical properties of bodies as related to heat we
have begun with solid bodies, as those which we can _most easily
handle_, and have gone on to liquids, which we can keep in open vessels,
and have now come to gases, which will escape from open vessels, and
which are generally _invisible_. This is the order which is most natural
in our first study of these different states. But as soon as we have
been made familiar with the most prominent features of these different
conditions of matter the most _scientific_ course of study is in the
_reverse_ order, beginning with gases, on account of the greater
simplicity of their laws, then advancing to liquids, the more complex
laws of which are much more imperfectly known, and concluding with the
little that has been hitherto discovered about the constitution of solid
bodies." That is to say that Science finds it easier to work among
gases--which are invisible and which we can know little about--than
among solids, which we are familiar with and which we can easily handle!
This seems a strange conclusion, but it will be found to represent a
common procedure of Science--the truth probably being that the laws of
gases are not one whit _simpler_ than the laws of liquids and solids,
but that on account of our knowing so much less about gases it is easier
for us to _feign_ laws in their case than in the case of solids, and
less easy for our errors to be detected.
[22] All our thoughts, theories, "laws," etc., may perhaps be said to
_touch_ Nature--as the tangent touches the curve--at a point. They give
a direction--and are true--at that point. But make the slightest move,
and they all have to be reconstructed. The tangents are infinite in
number, but the curve is one. This may not only illustrate the relation
of Nature to Science, but also of Art to the materials it uses. The poet
radiates thoughts: but he sets no store by them. He knows his thoughts
are not true in themselves, but they _touch_ the Truth. His lines are
the envelope of the curve which is his poem.
[23] See the report of the joint meeting of the Royal Society and the
Royal Astronomical Society, November 6, 1919, when Einstein's theory was
discussed.
[24] It is obvious that the Einstein theory, in which Time enters as a
kind of fourth dimension in relation to Space, removes us at once out of
the whole field of ordinary scientific reasoning and lands us, so to
speak, in a new world. The nature of Space (or of the universal medium,
whatever it is) in any region--its possible fundamental accelerations
there, its "curvature" or non-Euclidean character, and so forth--is
supposed, according to this theory, to vary with the amount of matter
in, or density of, that region; and the movements of bodies are
consequently supposed to take on the characters (accelerations, etc.,)
which we ascribe to the action of Gravitation. Gravitation in fact in
any region is the manifestation in Time of the attributes of the
universal Medium in that region--which latter again is dependent on the
degree of Matter present. Thus, Matter, Time, and Space are _one
phenomenon_.
The whole Einstein theory, in fact, is a device to present these three
Protean and variable elements of all material existence (Matter, Time
and Space) as so far involved and interlaced in each other that they
form always an absolute and complete unity. As such the theory is no
doubt suggestive, and along the line of future speculation: but it
awaits corroboration. If corroborated it will point the way to a new
conception of the Universe.
[25] J. S. Mill.
[26] See Stallo's excellent _Concepts of Modern Physics_.
[27] See, for instance, the last new thing in this style--the Helmholtz
molecule as improved upon by Sir William Thomson; it is described as
follows: "A heavy mass connected by massless springs with a massless
enclosing shell; or there may be several shells enclosing each other
connected by springs with a dense mass in the centre (far more dense
than the ether)." It is not, of course, seriously maintained that this
nonsensical creation exists--but that if it did exist it would account
for certain unexplained phenomena in the dispersion of light, etc.
Later still (1920) we have the following delightful verdict on the
Structure of the Atom, given by Sir Ernest Rutherford--and which I
commend to all lovers of clear thinking:--
"The Bakerian Lecture was delivered yesterday before the Royal Society
by Sir Ernest Rutherford, whose subject was 'The Nuclear Construction of
the Atom.' He said that during recent years much attention had been paid
to the nature and structure of atoms. The atomic theory of matter had
been definitely proved. The mass of the individual atoms, and the number
in any given weight of matter, were now known with considerable
accuracy. Not only was matter known to be made up of atoms, but
electricity was also atomic in nature, and there was a definite unit of
electrical charge which could not further be subdivided. The negative
electron, which was a constituent of all atoms of matter, was probably
nothing more than an isolated unit of negative electricity, and its
small mass was electrical in origin. It had long been considered
probable that the atom is an electrical structure, consisting of
positive and negative particles, held in equilibrium by electric or
magnetic forces. In recent years evidence had accumulated that an atom
consists of a positively charged nucleus surrounded at a distance by a
distribution of electrons to make it electrically neutral." (From _The
Morning Post_ of June 4, 1920.)
[28] The very fact alone that the degrees on a thermometer are _equal_
space divisions shows that they must bear a _varying_ relation to the
total volume of liquid as that expands from one end of the tube to the
other.
[29] A statement obviously applying--from what has been already said--at
only one point in the scale.
[30] I am not, of course, here arguing against the use of thermometers
or other instruments for practical purposes. This is certainly the
legitimate field of Science. But (as in the case of _prediction_ before
mentioned) the exactness of results obtained is a very different matter
from the truth of the generalities which are supposed to underlie these
results. In using a thermometer you need not even mention the word
"temperature."