EINSTEIN ALBERT: (1879-1955) German-born theoretical physicist, Nobel Prize winner for Physics, 1921. An excellent ...

EINSTEIN ALBERT: (1879-1955) German-born theoretical physicist, Nobel Prize winner for Physics, 1921. An excellent scientific A.L.S., with his initials A. E., two pages, 4to, n.p., 5th March 1950, to Ernst Gabor Straus, in German, incorporating two lines of calculations. Einstein announces 'Ich stimme mit der Meinung, die Sie in ihrem letzten Briefe geaussert haben, nicht uberein. Es liegt eben doch in der Natur der Suche, dass man verlangen muss, dass alle Tensoren, die durch Kontraktion von…. gewonnen werden konnen verschwinden' (Translation: 'I do not agree with the opinion you expressed in your last letter. It is precisely in the nature of research that one must demand that all the tensors that can be produced by means of the….contraction disappear') and continues to explain, 'Ich bin davon uberzeugt, dass man dies verlangen muss, trotzdem es nun sehr unwahrscheinlich geworden ist, dass es drei zusatzliche Identitaten gibt. Wenn man kompatible Gleichungen im Sinne der Fortsetzbarkeit einer jeden Schnittlosung verlangt, so gibt es mindestens drei formal gleichberechtgte am Variationssystemen gewahrbare, also im gewohnlichen Sinne kompatible Gleichungssysteme, dessen jedes weniger naturlich ist als das starke System, und zwischen denen eine Wahl in vernunftiger Weise nicht getroffen werden kann. Wenn das starke System so wenig Losungen haben sollte, dass die allgemeine Losung durch eine endliche Zahl von Zahlenparametern bestimmt ist, dann kame das starke System als physikalische Theorie naturlich nicht in Betracht. Dann aber ware ich uberzeugt, dass die Theorie des nicht symmetrischen Feldes uberhaupt aufgeben werden musste. Wenn aber die Mannigfaltigkeit der Losungen des starken Systems nicht in solcher Weise beschrankt ist, dann ist die Theorie nach meiner Ansicht sehr aussichtsreich. Denn es ist plausibel, dass das Thatreichliche Feldgesetz in seinen Losungen starker eingeschrankt ist, als es z. B. durch ein Hamilton-Prinzip erreichbar ist' (Translation: 'I am convinced that this should be required, even though it has now become very unlikely that there are three additional identities. If one demands compatible equations in the sense of a possibility of continuity of each cutting solution, then there are at least three formally equal systems of equations perceivable in the variation system, i.e. compatible in the usual sense, each of which is less natural than the strong system, and between which a choice cannot be made in a reasonable way. If the strong system should have so few solutions that the general solution is determined by a finite number of numerical parameters, then the strong system would of course not come into consideration as a physical theory. But then I would be convinced that the theory of the non-symmetrical field had to be abandoned altogether. But if the variety of the solutions of the strong system is not limited in this way, then the theory is, in my opinion, very promising. For it is plausible that the actual law of the field is more severely restricted in its solutions than it is, e.g. B. is achievable by a Hamilton principle) before concluding 'Dies ist durch die Quanten-Thatsachen sehr recht gelegt, die eben zeigen, dass die wahl der ''Anfangsbedingungen'' weitgehend eingeschrankt sein muss, was bei einem vollstandig durch ein variationsprinzip bestimmten gleichungssystem nicht der fall ist, wo eine erhebliche zahl von willkurlichen funktionen von drei variablen (fur die ''Schnittlosung'') frei bleibt. Das eigentliche problem liegt also darin, die mannigfaltigkeit der losungen des starken systems herauszufinden, hierein habe ich bis jetzt keinen erfolg gehabt' (Translation: 'This is very well justified by the quantum facts, which show precisely that the choice of ''initial conditions'' must be largely restricted, which is not the case for a system of equations completely determined by a variational principle, where a considerable number of arbitrary functions of three variables (for the ''intersection solution'') remains free. So the real problem lies in finding out the multiplicity of the solutions of the strong system, in which I have not had any success up to now'). In a postscript, in which Einstein incorporates his calculations, the physicist states 'In der neuen auflage des buchleins, die bald herauskommt, ist der schnitzer berichtigt. Ich habe mirs aber doch nicht nehmen lassen, zu erwahnen, dass sie den fehler entdeckt haben. Er lasst sich um Einfachsten so charakterisieren (his two lines of calculations inserted at this point) Bei dem andern ''Beweis'' ist es ganz entspechend' (Translation: 'In the new edition of the little book, which will be published soon, the blunder has been corrected. But I couldn't resist mentioning that it was you who discovered the error. It can be characterised in the simplest way (his two lines of calculations inserted at this point) In the case of the other 'proof', everything matches'). A letter of good association and fine scientific content. Some very light, extremely minor age wear, VG Ernst Gabor Straus (1922-1983) German-American mathematician, a close associate of Einstein who collaborated with the physicist on their early work on relativity. After publishing his papers on special relativity (1905) and general relativity (1916), Albert Einstein conducted research on quantum physics before working on the generalisation of the relativistic theory of gravitation. Einstein attempted to generalise his theory of gravitation to include electromagnetism as aspects of a single entity. In 1950, he described his 'unified field theory' in an article entitled On the Generalised Theory of Gravitation. Although he was lauded for this work, his efforts were ultimately unsuccessful. Notably, Einstein's unification project did not accommodate the strong and weak nuclear forces, neither of which was well understood until many years after his death. Although mainstream physics long ignored Einstein's approaches to unification, his work has motivated modern quests for a theory of everything.