Concerning the Investigation of the State of Aether in Magnetic Fields by Albert Einstein

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Albert Einstein s First Paper 9

C o n c e r n i n g t h e I n v e s t i g a t i o n o f t h e S t a t e o f A e t h e ri n M a g n e t i c F i e l d sThe following lines are the first modest expression of some simple thoughts on thisdifficult subject . W ith mu ch hesi tat ion I am comp ressing them into an essay whichlooks mo re like a progra m th an a pa per . Since I completely lacked the ma terialsto penetrate the subject more deeply than was permitted by ref lect ion alone, I askth at this circum stance should not be ascribed to me as superficial ity. I hope th eindulgence of the interested reader will correspond to the humble feelings with whichI offer him these lines.

When the electr ic current comes into being, i t immediately sets the surroundingaether in some kind of instantaneous motion, the nature of which has st i l l not beenexactly determ ined. In spite of the c ontinu ation of the cause of this motio n, n ame lythe electr ic current , the motion ceases, but the aether remains in a potential stateand produces a magnetic field. That the magnetic field is a potential state [of theaether] is shown by the [existence of a] permanent magnet, since the principle ofconservation of energy excludes the possibility of a state of motion in this case.The motion of the aether , which is caused by an electr ic current , wil l continue unti lthe acting [electro-] motive forces are compensated by the equivalent passive forceswhich ar ise from the deformation caused by the motion of the aether itself

The marvellous experiments of Hertz have most ingeniously i l luminated thedynamic nature of these phenomena the propagation in space, as well as thequa li tat ive identi ty of these motions w ith l ight and he at . I bel ieve th a t for th eunderstanding of electromagnetic phenomena i t is important also to undertake acomprehensive experimental invest igation of the potential states of the aether inma gne tic fields of al l kinds or, in other words, to mea sure th e elast ic deformationsand the acting deforming forces.

Every elastic change of the aether at any (free) point in a given direction shouldbe determinable from the change which the velocity of an aether wave undergoesat this point in that direct ion. The velocity of a wave is proport ional to the squareroot of the elastic forces which cause [its] propagation, and inversely proportional tothe mass of the aether moved by these forces. However, since the changes of densitycaused by the elast ic deformations are general ly insignif icant , they may probablybe neglected in this case also. I t could therefore be said with good approximation:The square root of the rat io of the change of velocity of propagation (wavelength)is equal to the ratio of the change of the elastic force.

I dare not decide as to which type of aether waves, whether light or electro-dynamic, and which method of measuring the wavelength is most appropriate forstudying the magnetic field; in principle, after all, this makes no difference.If a change of wavelength in the magnetic field can be detected at all in any givendirection, then the quest ion can be experimental ly decided whether only the component of the elastic state in the direction of the propagation of the wave influences*My t rans la t ion of E ins te in ' s e s say .



10 The Golden Age of Theoretical Physics

the velocity of propagation, or the components perpendicular to i t also do; sinceit is known a priori that in a uniform magnetic field, whether it is cylindrical orpyramidal in form, the elast ic states at a point perpendicular to the direct ion of thelines of force are completely homogeneous, but different in the direction of the linesof force. Therefore if one lets waves propagate that are polarized perpendicularlyto the direction of the lines of force, then the direction of the plane of oscillationwould be important for the velocity of propagation that is i f the component ofthe elastic force perpendicular to the propagation of a wave at all influences thevelocity of pro pag ation . However, this proba bly might no t be the case, al tho ughthe phenomenon of double diffract ion seems to indicate this.

Thus af ter the quest ion has been answered as to how the three components ofelasticity affect the velocity of an aether wave, one can proceed to the study of themagnetic f ield. In order to understand properly the state of the aether in i t [ themagnet ic field], three cases ought to be dist inguished:

1. The lines of force come together at the North pole in the shape of a pyramid.2. The lines of force come together at the South pole in the shape of a pyramid.3 . The lines of force are parallel.

In these cases the velocity of propagation of a wave in the direction of the lines offorce and perpen dicular to them h as to be examined. Th ere is no doub t th at theelastic deformations as well as the cause of their origin will be determined [by theseexperiments] , provided suff iciently accurate instruments to measure the wavelengthcan be const ructed .

Th e most inte rest ing, b ut also the m ost difficult , task would be th e direct experimental study of the magnetic f ield which ar ises around an electr ic current , becausethe investigation of the elastic state of the aether in this case would allow us toobtain a gl impse of the mysterious nature of the electr ic current . This analogy alsopermits us to draw defini te conclusions concerning the state of the aether in themagnetic f ield which surrounds the electr ic current , provided of course the experiments mentioned above yield any result .

I bel ieve that the quanti tat ive researches on the absolute magnitudes of thedensity and the elastic force of the aether can only begin if qualitative results existth at are conn ected with established ideas. Let me add one mo re thing . If thewavelength does not turn out to be proport ional to ^A + k [sic],the n th e reason(for tha t) has to b e looked for in the chan ge of den sity of th e moving a eth er cause d bythe elast ic deformations; here A is the elastic aether force, a priori a constant whichwe have to de term ine empirically, and k the (variable) strength of the magnetic fieldwhich, of course, is proport ional to the elast ic forces in quest ion that are produced.

Above al l i t must be demonstrated that there exists a passive resistance to theelectr ic current for the production of the magnetic f ield, that is proport ional tothe length of the path of the current and independent of the cross section and thematerial of the conductor .



Albert Einstein s First Paper 11N o t e s a n d R e f e r e n c e s

1. A. Einstein, Annalen der Physik, Ser . 4 , 17 , pp . 891-921 , 1905.2. Gera ld Hol ton , ' Inf luences of Einstein ' s Ea r ly Work in Re lat iv i ty T heory , ' The American Scholar, 37 , No. 1 , pp . 59-79, Winter , 1967-68 .3 . Alb er t Einstein was a pupi l in the th i rd and four th classes of the A arga u Ca nton al

School in Aarau from October 1895 to early fal l of 1896. In October 1896 Einsteinenrol led at the E.T.H., Zurich, to study for a Fachlehrer (special i s t t eacher) d ip lomain mathemat ical physics , and was graduated in August 1900. (See Car l Seel ig , AlbertEinstein, Stap les Pre ss, Lon don, 1956.) In his art icle ibid., p . 63) Ho l ton rema rks:'As Besso wrote ( in his notes of August 1946 for Strickelberg 's art icle on Einstein inSw i tzer land) , Einstein cam e to the Aa rau Kanton-Sch ool in 1896 ' Th ere i s a s l ightconfusion of dates in this. Both Seel ig and Einstein are correct about the dates.

4. Augus t Fopp l , Einfuhrung in die Ma xwellsche Theorie der Elektrizitdt, Druck undVer lag von B.G. Teubner , 1894.4a. Heinr ich He r tz ' Untersu chungen iiber die Elektrischen Kraft was published in 1892; thefirst English edition of his Electric Wav es was published in 1894 (McMillan and Co.L t d . ) . Her tz d ied in 1894. Paul Drude 's book Physik des Aethers was al so publ i she din 1894 (Ver lag von Ferdinand Enke, Stu t tgar t , 1894) .Einstein 's essay, presented in this art icle, clearly indicates that his interest in elec-t romagnet i sm was aroused by the 'marvel lous ' exper iments of Heinr ich Her tz . Theseexper iments , s ince Faraday 's ear ly work , were the most impor tant in the f ie ld of e lec-t rom agn et i sm and were jus t ly so celebrated a t the time . Fa rada y ha d d iscovered th elaw of e lect romagnet ic induct ion in 1834, and i t was th i s law that guided Einsteinin his work on Special Relat ivi ty. Einstein buil t his theory on experimental facts. Hestar t s h i s 1905 paper by poin t ing out that the law of induct ion contains an asymmetrywhich is art i f icial , and does not correspond to facts. Empirical observat ion shows thatthe current induced depends only on the relat ive mot ion of the conduct ing wire andthe magnet , while the usual theory explains the effect in qui te different terms according to whether the wire i s a t res t and the magnet moving or v ice versa. At the t imeof Eins tein ' s wr i t ing th e law of induct ion w as about 70 yea rs o ld , and 'every bod y hadknown al l a long that the ef fect depended on relat ive mot ion , but nobody had takenoffence at the theory not account ing for th i s c i rcumstance. ' (See Max Born , Physicsand Relat ivi ty, in Physics in My Generation, Springer Verlag New York, 1969.)

5. I am gratefu l to Madame Suzanne Koch-Got t schalk and Jean Ferrard for a l lowingme to examine the le t ters and papers relat ing to Einstein in the possess ion of thei rfami ly . Madame Got t schalk has very k indly al lowed me to publ i sh the t ranslat ion ofEinstein 's essay and to report on my findings for scient if ic purposes.6 . Cas ar and Ja kob Koch were the two broth ers of Einste in ' s moth er Pa ul ine . Jakob l ivedin Zur ich and h is name occurs several t imes in the Einstein-Besso correspondence.Casar Koch seems to have been Einstein 's favori te relat ive. In one of the let ters toC a s a r , E i n s t e i n r e m a r k s : ' . . . . Bist Du mir doch immer der Liebste in der Familiegewesen. After h i s marr iage to Mathi lde Levy at Basle in 1888 , Casar went to BuenosAires; fol lowing a sojourn there and return to Basle, he set t led in Antwerp, Belgium,aro und 1891, and m oved to Brussels af ter the Fi rs t W orld Wa r . He was a merc han t ofcommodi t ies . Casar Koch was very fond of Alber t Einstein and encouraged h im in h isboyhood s tudies . Einstein v is i ted the Koch fami ly when he at tended the f i rs t Solvayconference in Brussels in 1911. In the 1920's when Ein stein used to visi t Ehrenfes t inLeiden and gave lectures there, or en route to Paris from Berl in, he always visi ted hisuncle Casar . These personal contacts were cont inued when Einstein at tended the f i f than d sixth Solvay conferences in Brusse ls, in 1927 and 1930 respect ively, an d du rin g



12 The Golden Age of Theoretical Physics

the months he spent as a refugee f rom Germany at Le Coq sur Mer near Ostendebefore h is f inal dep ar tu re f rom E uro pe to the Uni ted S tates . Later on , af fectionatecorrespondence between Einstein , h i s wi fe Elsa, h i s s i s ter Maja, and the Koch fami lywas main t a ined .I am gratefu l to Madame Suzanne Got t schalk , daughter of Casar Koch, for conversat ions about Einstein and her fami ly , and for showing me numerous le t ters andpho tographs .7. I have not been able to discover the identi ty of the person who showed Einsteinthese documents in 1950. Nei ther the owners of the documents nor Miss Helen Dukas ,Einstein ' s former secretary , have any recol lect ion of who th is person was, nor couldthey offer any reasonable guess about his identi ty.

8. T he choice of th e E.T .H . in Zurich for Ein stein 's higher studie s was ma de by his fath erHermann and uncle Jakob Einstein . The two brothers a t one t ime had founded a smal lengineer ing factory for making dynamos, measur ing ins t ruments and arc lamps, andEinstein ' s in i t ia l p lan was to s tudy engineer ing in Zur ich .

9 . M ax W er the imer , Produ ctive Thinking, edi ted by Michael W ertheim er , Enla rged Ed i t ion 1959, Harper c Row Publ i shers , New York and Evanston , p . 213.10. In 1905 Einstein cont inued the theme of h is re lat iv i ty paper by d iscuss ing the dependence of the iner t ia of a body on i t s energy (Anncden der Physik, ser. 4, vol. 18,

p p . 639-641). In 1907 Einstein wrote on the possibi l i ty of a new test of the principle of relat ivi ty (Annalen der Physik, ser. 4, vol . 23 , p p. 1 97-198 ), the ine rt ia ofenergy as a conseq uence of the relat iv i ty pr incip le (Annalen der Physik, ser. 4, vol. 2 3 ,p p . 371-384) , and 'Re lativ itat sp rin zip un d die aus demselben gezogenen Folgerungen(Jahrbuch der Radioa ktivitat, vol. 4 , pp . 411-462 , and vol . 5 , pp . 98 -99) . In the las tpaper he expl ici t ly s ta ted the equivalence of iner t ia l and gravi tat ional mass , and gavethe famous equat ion for mass in terms of energy. Einstein returned to the ideas of th i spaper in 1911 when he wrote on the influence of gravi ty on l ight (Annalen der Physik,ser . 4 , vol . 35 , pp . 898-908) . The theme of relat iv i ty and gravi tat ion was taken up in1912, with papers on the veloci ty of l ight in a gravi tat ional f ield (Annalen der Physik,ser. 4, vol . 38, pp. 355-369), the theory of a stat ic gravi tat ional f ield (Annalen derPhysik, ser . 4 , vol . 38 , pp . 443 -458) , and repl ies to remark s of M. Ab rah am in sho r tno t es (Annalen der Physik, ser. 4, vol . 8 , pp. 1059-1064; vol . 39, p. 704). A major summing up of the ideas expressed in these papers and approaches to the general theoryof relat iv i ty and gravi tat ion were made wi th Marcel Grossmann in Entwurf einer Ve-rallgemeinerten Relativitdtstheorie und eine Theor ie der Gra vitation (Zeitschrift furMathematik and Physik, vol. 62, pp . 22 5-261 ) . Einstein prese nted a lecture on the physical foundat ions of the new theory of gravi tat ion in an address to the NaturforschendeGesellschaft, Zur ich , 9 Sep temb er 1913 (Vierteljahrsschrift, vol . 58 , pp . 28 4-290 ) , andcont inued the theme two weeks la ter in a lecture at the 85th Versammlung DeutscherNaturforscher in Vien na on 21 Sep temb er 1913. In 1914, Einstein wrote on th e formalfoundations of general relat ivi ty theory (Sitzungsberichte der Preussischen Akadem ieder Wissenschaften, par t 2 , pp . 1030-1085, 1914) , gave several lectures on the prob lemof gravi tat ion and relat iv i ty , and publ i shed a paper wi th M. Grossmann on the generalconvariance propert ies of the f ield equations of the theory of gravi tat ion (Zeitschriftfur Mathematik und Physik, vol . 63 , pp . 215-225) . Einstein cont inue d to wr i te on general re lat iv i ty dur ing the year 1915, and publ i shed new ideas on the appl icat ion of thetheory of as t ronomy; he al so explained the per ihel ion mot ion of mercury on the basisof the general theory . Then in 1916 h is great paper on the complete general theoryof relat ivi ty was published: 'Gru ndlage der allgemeinen Relativitats-theorie (Annalender Physik, ser . 4 , vol. 49 , pp . 769-822 ) . In an imp or ta nt sense th i s was the c ulmin at ion



Albert Einstein s First Paper 13

of the in tel lectual adventure on which Einstein had s tar ted s ince the t ime he wrote tohis uncle Casar Koch in 1894 or 1895.11. M ax Wer the imer , ibid., p. 214.12 . R.S. Shankland, 'Conversat ions wi th Alber t Einstein , ' American Journal of Physics,vol . 31 , pp . 47-57, 1963, p . 48 .13 . R .S . Shank land , ibid., p. 48.14 . R . S . S h a n k l a n d , ibid., p. 56.15 . A pa r t f rom quest ions concerning l ight and the elect rodyna mics of moving bodies , Eins tein went to Aarau 'wi th the [ then much debated] quest ions concerning the palpabi l i ty

[GreifbarkeiQ of ether and of atoms' in mind. (For the quotat ion from Besso in thisremark , see Hol ton , ibid., p. 63.)16 . Autobiographical notes by Alber t Einstein in Albert Einstein, Philosopher -Scientist,ed ited by Pa ul A rth ur Schilpp (original ly in Lib rary of Living Philosop hers, 1949),

Harper Torchbooks Science Library, New York, 1959, p. 9.17 . Au tobiogra phica l notes by Alb er t Einstein , ibid., p. 15.18 . Ca rl Seel ig, Albert Einstein, Stap les Pre ss, Lo ndon , 1956, p. 12.19 . Alber t E ins t e in , Autobiogra phische Skizze; perhaps one of the las t wr i t ings of Einstein (wri t ten in March 1955), was published in Fal l 1955 in ' Schweizerische Hoch-

schulzeitung, Festnummer 1855 -1955, on the occasion of the cente nnia l jubi lee of th eE.T.H. in Zur ich . In th i s au tobiographical sketch , Einstein recal led some touchingmemories of his l i fe in Switzerland. This sketch was included in Helle Zeit Dun-kle Zeit, In Mem oriam Albert Einstein, edited by Carl Seel ig, E ur op a Verlag, Zurich,1956, pp. 9-17. See pp. 9-10 for the quotat ion.

20. Einstein: The Man and His Achievement, a ser ies of broa dca sts on the BBC T hi r dProgramme, ed i t ed by G .J . Whi t row, BBC, London , 1967 .21. M ax We r the imer , ibid., p. 215.

21a. A. Pais , Subtle is the Lord, Oxford Universi ty Press, 1982, p. 131.22. Louis Kollross, Albert Einstein en Suisse Souvenirs, in Funfzig Jahre Relativ-itatstheorie (Bern, 11-16 July 1955), Helvetica Physica Acta, Supplementum IV, 1956,see pp. 274-275; also published as 'Erinnerungen eines Kommilitonen in Helle Zeit Dunkle Zeit, ibid., see p. 22.23 . In an und ated le t ter , proba bly som et ime af ter 6 March 1905, Eins tein wrote to h isfr iend Conrad Habicht in Schiers; 'But why have you not yet sent me your thesis? Don'tyou know, you wretch, that I should be one of the few fel lows who would read i t withinterest and pleasure? I can promise you in return four works, the f i rst of which I shal lsoon be able to send you as I am get t ing some free copies. I t deals with the radiat ionand energy characterist ics of l ight and is very revolut ionary, as you wil l see i f you sendme your work in advance. The second s tudy i s a determinat ion of the t rue atomic

dimensions from the diffusion and inner fr ict ion of di luted l iquid solut ions of neutralmat ter . The th i rd proves that on the premise of the molecular theory of induct ion ,part icles of the size 1/1000 mm., when suspended in l iquid , must execute a percept ib lei r regular movement which i s generated by the movement of heat . Movements of smal l ,l i feless, suspended part icles have in fact been examined by physiologists and thesemo vem ents have been called by them the Brownian movem ent . The fourth study isstill a mere conce pt: the electrodynam ics of mo ving bodies by the use of a mod ificationof the theory of space and time. The purely cinem atic part of this work will undou btedlyinterest you. (My i tal ics.)

The fourth study, to which Einstein refers, was his paper on the Special Theoryof Relat ivi ty. I t was completed in Berne in June 1905, and received by the edi tor ofAnnalen der Physik on 30 Jun e 1905. I t is indeed qui te remarkab le th at even at th i s la te



14 The Golden Age of Theoretical Physicsda te (som etim e after 6 M arch 1905), Ein stein refers to his stu dy as 's t i l l a m ere concept . ' This concept , however , had now been growing wi th in h im for a lmost ten years .On March 11 , 1952, Alber t Einstein wrote to Car l Seel ig : 'Between the concept ionof the idea of th i s special re lat iv i ty theory and the complet ion of the correspondingpublicat ion, there elapsed five or six weeks. But [he added rather cryptical ly] i t wouldbe hardly correct to consider th i s as a b i r thdate , because ear l ier the arguments andbui ld ing b locks were being prepared over a per iod of years , a l tho ugh wi th out br ingingabout the fundamental decision. ' (See Ref. 2, p. 60.) Michele Besso, Einstein 's fr iendand col league at the Patent Off ice in Berne, was par ty to the ' fundamental decis ion , 'the f inal progress of Einstein 's conception, and i ts publicat ion. In concluding his paper , Einstein wrote , ' I wish to say that in working at the problem deal t wi th here, Ihave had the loyal assistance of my friend and col league M. Besso, and I am indebtedto him for several valuable suggest ions. '

Concerning the Investigation of the State of Aether in Magnetic Fields by Albert Einstein

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