A Canadian Conference in Physics

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The Building Guild Movement A Canadian Conference in Physics
written by Author:H. A. M.
Sonnet (Arvers)
From The Canadian Forum, February 1921, p. 140



Popular education is becoming more popular. It is even being taken seriously. The days are gone when scientific knowledge was the pursuit and possession of a few.

Having in mind the considerable number of discoveries in physical science in recent years, Prof. McLennan, head of the Physics Department in the University of Toronto, suggested holding in Toronto a conference of all those, both inside and outside University circles, who are taking an interest in such advances. The idea was heartily approved by the University authorities and a series of public lecture courses to extend over a period of three weeks was arranged. The principal courses offered were one on Relativity by Dr. Silberstein, formerly of the University of Rome, one on Atomic Structure by Professor McLennan, and one on Colloids by Professor Burton. Dr. Louis King of McGill University, and Dr. I. Langmuir of the General Electric Company of Schennectady(sic!), N.Y., also gave addresses.

The conference was opened on January 5 by the President of the University, Sir Robert Falconer, and the sessions were continued till January 26.

It came as a surprise to those interested to find in attendance such a large number, not only of scientists, but of "the man in the street." That such a physico-philosophical and abstruse subject as Relativity or even a discussion of atomic architecture should arouse so wide an interest was scarcely to be expected. It recalled to mind the meetings of the Royal Institution in old London or the public attention given to Bergson's lectures in Paris a few years ago.

The visiting lecturer. Dr. Silberstein — well known in the field of Mathematical Physics — gave a very interesting course in Relativity, a subject necessarily mathematical in its nature, especially in its modern development, but presented by Dr. Silberstein in a very picturesque and lucid manner.

To give an idea of the scope of the subject in a few words would be impossible. We, ourself, took down reams of notes and yards of mathematical equations to keep ourself out of mischief in the summer holidays, but they are too voluminous to reproduce here. To be very brief, the Relativist wants to find out how things, i.e. physical phenomena, look when viewed from the vantage point of a body moving relatively to our earth, or, contrariwise, to find out from our vantage point on the earth what errors we make in observing bodies in rapid motion relative to us. He sets out on this curious quest partly at the instigation of those physicists who discovered the electron and cannot explain its behaviour — one of its idiosyncracies being that it weighs more the faster it goes.

Well, to launch out on this quest one must have a "jumping off" place, so to speak, so the Relativist lays down a postulate or two just as Euclid does, and, like Euclid, he arrives at results in agreement with our everyday experience, and herein, as Dr. Silberstein pointed out, lies the value of the theory of Relativity or of any theory for that matter.

The Relativist first challenges you to find a spot in the universe absolutely at rest, and if you point to one that looks as if it were he asks you to prove it. Since, of course, you cannot, he lays down as a reasonable postulate that there is no spot in the universe which can be regarded as at rest — in other words, that all motion is relative.

Then you are asked to admit that necessarily your observations on phenomena must be warped more or less since viewed from only one standpoint. To the uninstructed, the sun moves around the earth. It appears to do so because the observer has forgotten to consider a possible motion of his point of vantage. The Relativist is convinced we are all uninstructed in this respect and must forever remain so. Could we but find a spot at rest from which to look out upon the world, things would appear as they really are. Since we cannot, we seek some simple relation connecting the march of events as viewed from different points of vantage.

To arrive at such a relation the Relativist lays down another postulate. He says — "Take any physical phenomenon in nature, for simplicity, the velocity of light in space; I postulate that its velocity as measured by an observer from any point of vantage will always be the same." This postulate or "principle of relativity" as it is called may be stated more generally thus — "if, relative to K, Kʹ is a uniformly moving system devoid of rotation, then natural phenomena run their course with respect to Kʹ according to exactly the same laws as with respect to K. In other words if we know the truth about a series of events no point of vantage would enjoy a privilege over another in observing it."

Well, if you agree to this then the Relativist begins to lead you on as Euclid did from one curious fact to another, as, for example, that a railway carriage rushing past you at 60 miles an hour is not as long as it is when standing still, and he gives you the law governing the observed change in length. Or, again, that a clock beating seconds on the station platform will if observed from a swiftly moving train beat longer seconds. He shows you that a second is not always a second but varies with the observer's point of vantage, and he gives you the relation connecting them. To make a long story short he runs the electron to earth finally and tells you why it has a greater mass when it moves faster.

[p. 141]
The electron is, however, not the only object of his attention. The question of the effect of a gravitational field on the propagation of light is considered, as for example the bending of a beam of light passing near the sun — a phenomenon observed during the last eclipse. Or again the apparent shift — aberration it is called — in the position of a star, due to the observer's annual "high-speed" excursion to and fro in space around the sun.

The whole subject was very clearly divided by the lecturer into the Newtonian or earlier relativity, the so-called "special" relativity, and the most recent "general" relativity as developed by Einstein.

In the series of lectures given by Professor McLennan the subject dealt with was the atom — the home, so to speak, of the electron. The lectures were illustrated by a large number of experiments in the preparation of which the lecturer was assisted by Mr. J. F. J. Young[1] and Mr. H. J. C. Ireton of the Physics Department.

After leading his hearers into the molecular and atomic world, Dr. McLennan introduced them to that most outstanding discovery in modern physics, the electron, which emerged from the "dust and twine" of J. J. Thomson's laboratory about 20 years ago. Its importance from the point of view of the structure of the atom itself is very great indeed and it is attracting an increasing share of attention. Even that school of chemists who dismiss the atom as a needless fiction are being persuaded to recognize the electron. The atom was a hypothesis perhaps, but the electron is a reality. It has been weighed, measured and handed about from one place to another in a way the atom never dreamed of. Not only so but the atom itself is no longer a hypothesis. Thanks to information supplied by the electron, the form of the atom, its size, and its transformations are coming slowly to light; and as Professor McLennan pointed out, it is now a very reasonable hope of physicists that before long we shall know the structure of a great many, if not all, of, the atoms comprising the various elements.

The most interesting feature of the electron is perhaps its elemental negative charge of electricity. The movements of the electrons carrying with them this charge have been the subject of important mathematical investigations by Larmor in England and Lorentz in Holland and the results of these investigations have been the real inspiration of the modern theory of Relativity.

The lecturer also gave a very clear account of the field of spectroscopy from the electronic point of view pointing out the importance of series spectra and indicating how these were used to obtain information as to the number and arrangement of the electrons in an atom. For example, it is found that the three simplest atoms are hydrogen, helium, and lithium, and these are believed to have one, two and three electrons respectively revolving about a central nucleus, like moons about a planet.

Still other avenues of approach are being used to arrive at a clearer view of atomic structure. The passage of alpha particles and x-rays through atoms and the very important researches of Sir Ernest Rutherford on the nucleus of the atom were described and illustrated. The lectures form an excellent resumé of the work in that large field now known as atomic physics.

The third course of lectures on Colloids, given by Professor Burton, appealed more perhaps to those engaged in industrial pursuits. In the "colloidal" form matter exists in small particles, not indeed of electronic or even molecular dimensions, but still in particles small enough to be jostled about by molecules, much as a stout man might be pushed about by school boys. This "Brownian" movement was exhibited under the microscope in the case of small particles of smoke in air and again under the ultra-microscope in the case of very small copper particles in water.

Methods were described not only of preparing these colloidal solutions but of studying their size, electrical charge, stability and coagulation. Emphasis was laid on the growing industrial importance of the study of colloids, as for example, in the rubber industry, the cement industry and the dye industry.

The conference exceeded expectations, visitors being present from the far west and far east of Canada as well as from the French Universities of Quebec and even from the United States. The holding of an all-Canadian conference of this nature cannot fail to stimulate in the public mind a greater national enthusiasm. We are inclined to look abroad for leadership. It is sometimes forgotten that there exist in our Dominion great public works — feats of electrical and structural engineering carried to completion by Canadian engineers, — which attract attention from even the older countries, to say nothing of the newer.

In pure science Canadians have done a good deal and will do more. The conference was a demonstration of this fact.

H.A.M.
1. Wikinote: Sic! John Francis Todd Young.