HISTORY OF RELATIVITY.

Press, Volume LVII, Issue 17220, 10 August 1921, Page 12

HISTORY OF RELATIVITY.

PROFESSOR EINSTEIN IN LONDON. BRITISH WELCOME TO GENITJS. (PP.Olt OtE OWN- CORRESPONDENT.) LONDON, June 16. 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, ifa Lord Haldane's opinion, he 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 met, among others, the Archbishop of Canterbury and the -Astronomer Royal. AppfijJations for tickets to attend Professor „Einstein's lecture were sufficient in number to fill the great hall at King's College four times over. On the platform were gathered many Men of light and learning, 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, l if they know_ tho language, followed the, mazes of his labyrinthine arguments. But all behaved as if they did. They sat with craned necks and eager, earnest, rapt-looking faces. Not a sound was heard until, towards tho end of the lecture, the professor's face was lighted up with an irresistibly fascinating smile, when the tension was broken by a peal of laughter. Genius Knows M"o Frontier.

"To give a British welcome to a man of genius." These were, the words in which 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 the genius of Newton. When our distinguished guest left my houso this morning, he went to gazo on the tomh of Newton (Westniinster Abbey). Thus Newton of tho eighteenth -century was honoured by Einstein on tho. twentieth. Professor Einstein is distinguished not alone for his learning, but for his modesty, his s&f-effacement.. And yet he has been impelled, by tho -power of genius, not to rest in giving out oi his creative imagination." •It gave fefm 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 tho proposition of the electro-magnetic field oh 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 of the elaborate the ideas of Maxwell and Lorentz by endeavouring to,apply the physics of "fields" to all physical phenomena,, including the phenomena of gravitation. ."'."' ;•*' Professor pointed out that tjao theory of-relativity, was not of any Bpeoulativo origin, but had its origin solely; in tine endeavour to adapt the theory of factsjobserlved. It must not be considered as an arbitrary -'": act, bub rather as tbotesult of thb.obBervntions of .facts, the concep+ions ■of Bpabe,., time,. r and .potion, hitherto vl^d./aB/--.ittnda^ntol, : ''i|ui'd' now been - abandoned. Tworaainiactors,have-Jed p: aodeTO; v scieiice ; •-,to ; as 7a ■'■:, .iri;iso _; with. i.C;jts/bwnfjpeetuiar r time r ;';th'e-law;< of cpn- <' mancy^or the .velocity of light) in-vacuo, ; :by the development ofythe 'science, of electro-dynamics and optics, and in'Wnlnexion therewith theequiva".lifeiceof all inertiaj systems (special ptincijpfe of jrektivi<7), as clearly shown ''; By; Nicholson's famous experiment. In . dwelopiri that mtihsrtb the">int«r-cbnnoxion between direct ©rentsi'ori the one hand, and the ajpaeie:; cojolrflhiates v and time on the' :-. bad 1 not ;.beeu thought out with ■ -■,■ ,v- 'i'\

The Gravitational Field. > 'ln the realm of the specialftheory of ' reUitiyity, space and time were still of f"; absolute nature in so far as tJhey apared to be measurable by rigid'bodies, rods, and by clocks.< They weie'ider tTO&dent/ upon the motion, peculiar to 'ilme, inertihl system from, which they , were, observed. Accordingvto the special ' theory; pf relativity, the iout-dimensiops " gontiinum (postulated by Minkowsky) ", - formed by-tbo amalgamation of time and apace, retained, that absolute character 1 > which, according to ttoe previous theo- , Ties, ,< was attributed to epace as well as L to "time. a That led to the conclusions tnat motion (relative to the »eystem of corOrdinates) mfiuenoed the shape of* >- bodjes and the -working of clocks; that „ energy and inertial mass were equiva- *• ]en,t. The generalv theory, of relativity at by extending the appli-cataptt-of-'the 1 principle of relativity to - CTstetns of coordinates accelerated with ftfarehoe to one another. It offered a r ,-gieory 1 of the gravitational fieitf. A generalisation of metrics, which in,the iflphete of pure mathematics dated back f Gauss and Reitnantf, was based large* on the fact that the "metrics of the. Special theory of relativity might be trisidered J to apply in certain doses also _, .theory of relativity. In i Consequence, the co-ordinate system of * epajce.and time was no>longer a reality , m itself. Only by .connecting the space 1 v i&S 10 * 1 * fi ? u £ sS whlcb < defined' the gravitational "field could Uhe objects which % might be„meaßured by'measuring lods , and Jby docks bo determined. ' * *\ The.idea of the general theory of rotating had yet; another basis. \As Ernest Maeh eitipbdsised,'. the Now- * toman theory of motion was unsatisfacwry? because;if were regarded ~ w* wm the.casual but from the purely »sonj?Uve point of /view, it would be ftund that there'oxisted" a' relative 'mo- - tk&tjaf bodies" witlh, reference to each But the conception of rela+ive a did not of itself suffice to foret tho factor of acceleration to be equationsof motion. fwi was forced a fipti-' physical space, with reference to "«a acceleration was supposed to 'ti^- 3 J H s?^ on s e - >ti i >n of absolute space * sE§fl^vby,ss"%»-ad *bio *tisfaetory, although logically oor\ls^«s™r l » tb endeavoured'so *« • fcho nifiohanical equations that A»» .inertia of todies was attributed to their relative" motion with reference to absolute space, but with refer- '* T 06 !."? 0 "** snm tot *- °-" otne r iiea- * SR* 1 !? 0 bodies. Mach was bound to w, ooxutidtirihg the state of know- * "r 86 *?, ™ *""». But it was quite Bftasonable to put the problem as he Si i j :^ Tl6 i w . of i t!ho general theory of relativity, this line 0 f thought came fe'^R^SSfe*ptshefore, because: ao*rdingi to the theory of relativity, the W?2M?< -Patter. Concluding, Prothat the general theory-of relativity must regard the J£Wi" , "!? o r& r finite and closed. Jaejftatiiemalacal results of the theory 2LP?Sr!? ty foreed scientists to this -2^'is/v the y, L assiuned that the average i^ssys^**?" 1 *• **** is J&?fey*W t, » . -K»- tb - of. their wpMffa dumer*raven'by-the princi- , Q&' 1 P a & °uk&i the latter, S"**?? 8 w German, said that the rela>>l&pn*tiiUß resumed give us at least one }, japtfgfr line that-would always remain, . Jftme»y> the straight Hne of right and >■ • <l^fe|feP-dKsi4»x. l !? as .convinced, that - ? i ,

the parallel lines of English and German thought would, in; spite, of Euclid, bring the two nations together in friendship with one another, and with the other nations of the earth.

Lord Haldane, , who supported the toast, eaid that, after living with Professor Einstein for several days, he waa profoundly impressed by the simplicity and truth of his character. Hub intercourse had confirmed his previous impression that there is a fascination about a mathematician that is not found in any other society. He declared that Professor Einstein h 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. j