RELATIVITY

Evening Post, Volume CII, Issue 32, 6 August 1921, Page 7

RELATIVITY

PROFESSOR EINSTEIN COMES TO

LONDON x

BRITISH WELCOME TO GENIUS.

(HM)M OUR OWN CORRESPONDENT.)

LONDON, 16th June

Professor Einstein, of "relativity" fame, came to London this -week to explain here in German his great addition to human thought. Lord Haldane, with whom the Professor is staying, met him, on arrival, and greeted him in German. Professor Einstein himself is a short, thick-set man of sallow complexion and knit brow, with luxuriant iron-grey hair' that defies the brush and comb. He looks like a musician, and it is no surprise to hear < that, in Lord Haldane's opinion, ho is as great a master of the violin as he •is of mathematics.

At dinner at Lord Haldane's house on the night of his arrival the Professor viet, among others, the Archbishop of Caivtwbury and the Astronomer-Royal. Applications for tickets to attend Professor Einstein's lecture were sufficient in number to" fill the great hall at King's College i'oui*- times over. On' the platform were gathered many men of light' 'and learning, 1 and in the audience were nearly as many women as men. It is doubtful whether all of those in the audience understood Professor Einstein's German, or, if they knew the language, followed the mazes of his labyrinthine arguments. But all behaved as if they did. They sat with -craned necks and «ager, earnest, rapt-looking faces. Not a sound was heard ■ until, towards the end of the lecture, the Professor's face lighted up with an irresistibly fascinat-- " ing smile, when the tension was broken ■ fey a peal of laughter. GENIUS' KNOWS NO FRONTIER. "To give a British welcome to a man of genius." Thesu were the words in whioh Lord Haldane opened his introduction of the Professor. "Genius knows no frontier," he continued. "We are grateful to. Germany for the genius of Einstein, as Germany is grateful to England for tlie genius of Newton. When' our distinguished guest left my house' this morning he went to gaze on the tomb of Newton (Westminster Abbey). Thus Newton of the 18th century was honoured by Einstein of the 20th. Professor,, Einstein is distinguished not alone for his learning, but for his modesty, his self-effacement. And yet he has been impelled, by the power of genius-, not to rest in the giving outiof his creative imagination." It gave him special pleasure, said the Professor, to lecture in the capital of that country from which the most important and fundamental ideas of theoretical physics had spread throughout the world—the theories of motion and gravitation of Newton and the proposition of the electro-magnetic field on which Faraday' and Maxwell built up the 'theories of modern physics. It might well be said that the theory of relativity formed the finishing stone of the elaborate edifices of the ideas of Maxwell and Lorentz, by endeavouring to apply the physics of "fields" to all physical phenomena, including the phenomena of gravitation. SPACE, TIME, AND MOTION. Professor Einstein pointed out that tho theory of relativity was not of any speculative origin, but had its origin solely in the endeavour to adapt tho theory of physics to facts observed. It must not be considered as ail arbitrary uct. but rather as the result oi the obei v ation of facts, that the conceptions of space, time, and motion, hitherto held as "fundamental, had now been abandoned. Two main factors have led modern science to regard time as a relative conception insofar as each inertial system had to be coupled with its own peculiar time; the law of constancy of the velocity of light in vacuo, sanctioned by the development of sciences of electro-dynamics and option, and in connection therewith the equivalence of all inertial systems (special principle of relativity) as clearly shown by Michelsen's famous experiment. In developing^thia idea it appeared that hitherto the interconnection between direct events on the one hand, and the space co-ordinates and time on the other, had not been thought out with the necessary accuracy. THE GRAVITATIONAL FIELD. In the realm of the special theory of relativity, space and time were still of an absolute nature insofar as they appeared to be measurable by rigid bodies, by rods, and by clocks. They were dependent upon the motion peculiar to the inertial system from which they were observed. According to the special theory of relativity the four-dimensions continuum (postulated )>y Minkowsky) formed by the amalgamation of time and space, retained that absolute character which, according to the previous theories, was attributed to space as well as to time. That led to the conclusions that motion (relative to the system of coordinates) influenced the shape'of bodies and the working of clocks; that energy and inertial mass were equivalent. The general theory of relativity was arrived at by extending the application of the principle of relativity to systems of coordinates accelerated with reference to one another. It offered a theory of the 'gravitational field. A generalisation of metrics, which in the sphere of pure mathematics dated back to Gauss and Roimann, was based largely on the fact that the metrics of the special theory of relativity might ba considered to apply in certain cases also to the general, theory of relativity. In consequence the coM'dinate system of space and time was no longer a reality in itself. Only by connecting* the space and time co-ordi-nates with those mathematical figures which defined the gravitational field could the objects which might be meaeured by measuring rods and by clocks he determined. NEWTON'S VIEWS OF MOTION. : The idea of the general theory of relativity had yet another basis. Aa Ernest Ma,ch emphasised, tho .Newtonian theory of motion was unsatisfactory, because if motion • were regarded not from -the casual but from the purely descriptive point, of view it would be found that there existed a relative motion "of bodies with reference to uach other. But the conception of relative motion did not of itself suffice to formulate the factor of acceleration to be found in Newton's equations of motion. 1 Newton was forced to introduce a fictitious physical space with reference to which nn acceleration was supposed to exist. This conception of absolute space introduced by Newton ad hoc was unsatisfactory, although logically corteqt. ■Each, therefore, endeavoured so to alter the mechanical equations that the inertia of bodies was attributed to their relative motion with reference not to absolute space, but with reference'to the sum total of all other measurable bodies. Each was bound to fail, considering the state of knowledge at his time. 'But it was quite reasonable to put the problem as he did. In view of the general theory of relativity, this line of thought came more and more to the fore, because, ac- . cording to the theory of relativity, tlie phyical properties of space were influenced by matter. Concluding, Profes' sor Einstein said that the general theory of relativity must regard the universe as spacially finite and closed. The mathematical results of the theory of relativity forced scientists to this view,'

if they assumed that the average density of matter within the universe was of finite value.

In proposing the health of their guest at a dinner given by ths Principal of King's College, the latter, speaking in German, said that tho relations thus resumed give us at least one straight lino that would always remain, namely, the straight line of right and.of justice, and he was convinced that the parallel lines of English and German thought would, in spito of Euclid, bring the two nations together in friendship with ono another, and with the other nations of the earth. GREATER THAN NEWTON. Lord Haldane, supported the toast, said' that after living with Professor Einstein for several days he, was profoundly impressed by the simplicity and truth of his character. This intercourse had confirmed his previous impression that there is a fascination about a mathematician that is npt found in any other society. Ho declared that Professor Einstein is a man who is leading thought into a new plane, who has stirred up a tremendous emotion in the minds of the world, who has caused a revolution in our outlook greater than that caused by Newton, and who has accomplished for this century as much as anything accomplished by anyone in any previous century.