DCP Foundation #1: Einstein Said Relativity Theory is Not Fundamental

DCP Foundation #1: Einstein Said Relativity Theory is Not Fundamental © 2026 by Emory Taylor and Rajan Iyer
is licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International. To view a copy of this license, visit https://creativecommons.org/licenses/by-nc-nd/4.0/.

Introduction
Einstein (1) published his development of special relativity (SR) in 1905, and (2) published his development of general relativity (GR) in 1915 [1, 2]. The two components of relativity theory are SR and GR [3]. Relativity theory requires the continuum concept [3]. Since relativity theory requires the continuum concept, it logically follows that the continuum concept must be fundamental for relativity theory to be fundamental --- if the continuum concept is not fundamental, then relativity theory is not fundamental.

John Stachel and Einstein
Dr. John Stachel was a physicist and the Founder and Head of the Center for Einstein Studies at Boston University, where his work focused on Einstein and his publications [4-7]. Stachel published “The Other Einstein: Einstein Contra Field Theory” in 1993 and 2002, and then, on October 23, 2005, he gave a presentation about "The Other Einstein" at the Perimeter Institute for Theoretical Physics in Canada [8-10].

John Stachel and Einstein’s Skepticism
According to Stachel, "Besides the well-known advocate of unified field theories, there was 'another Einstein,' who was skeptical of the continuum as a foundational element in physics...” [8-10].

The Importance of Einstein’s Unification and Skepticism
As an advocate of unified field theories, Einstein believed that, instead of theoretical physics providing a general relativistic theory of macroscopic phenomena and a quantum theory for atomic and quantum phenomena, theoretical physics must provide a unified foundation on which the theoretical treatment of all phenomena could be based [11]. Einstein’s skepticism about the continuum concept is important because if the continuum concept is not fundamental then relativity theory cannot be fundamental. At best, if the continuum concept is not fundamental, relativity theory would be only a first approximation of a more fundamental theory.

John Stachel Makes His Point
To make the point that Einstein was skeptical about the continuum concept and thereby skeptical about relativity theory being fundamental, Stachel provided the fourteen pages of information in “The Other Einstein: Einstein Contra Field Theory” [8,9]. Among this information Stachel included three letters Einstein wrote in 1954 [8,9].

Einstein’s 1st Letter
"I consider it entirely possible that physics cannot be based upon the [continuous] field concept, that is on continuous structures. Then nothing will remain of my whole castle in the air including the theory of gravitation, but also nothing of the rest of contemporary physics (Einstein to Besso 10 August 1954...)” [8].

Einstein’s 2nd Letter
"The alternative continuum-discontinuum seems to me to be a real alternative; i.e., there is here no compromise. By discontinuum theory I understand one in which there are no differential quotients. In such a theory space and time cannot occur, but only numbers and number-fields and rules for the formation of such on the basis of algebraic rules with exclusion of limiting processes. Which way will prove itself, only success can teach us.

"Physics up to now [1954] is naturally in its essence a continuum physics, in spite of the use of the material point, which looks like a discontinuous conceptual element, and has no more right of existence in field description. Its strength lies in the fact that it posits parts which exist quasi-independently, beside one another. Upon this rests the fact that there are reasonable laws, that is rules which can be formulated and tested for the individual parts. Its weakness lies in the fact that it has not been possible up to now [1954] to see how that atomistic aspect including quantum relations can result as a consequence. On the other hand dimensionality (as four-dimensionality) lies at the foundation of the theory.

"An algebraic theory of physics is affected with just the inverted advantages and weaknesses, aside from the fact that no one has been able to propose a possible logical schema for such a theory. It would be especially difficult to derive something like a spatio-temporal quasi-order from such a schema. I cannot imagine how the axiomatic framework of such a physics would appear, and I don’t like it when one talks about it in dark apostrophes [Anredungen]. But I hold it entirely possible that the development will lead there; for it seems that the state of any finite spatially limited system may be fully characterized by a finite number of numbers. This speaks against the continuum with its infinitely many degrees of freedom. The object is not decisive only because one doesn’t know, in the contemporary state of mathematics, in what way the demand for freedom from singularity (in the continuum theory) limits the manifold of solutions (Einstein to H. S. Joachim 24 August 1954...)” [8].

Einstein’s 3rd Letter
"I must confess that I was not able to find a way to explain the atomistic character of nature. My opinion is that if the objective description through the [continuous] field as an elementary concept is not possible, then one has to find a possibility to avoid the continuum (together with space and time) altogether. But I have not the slightest idea what kind of elementary concepts could be used in such a theory (Einstein to David Bohm 28 October 1954...)” [8].

John Stachel and Einstein’s Last Words on the Continuum Concept and Relativity Theory
On page twelve (of fourteen), Stachel provided Einstein’s last published words concerning the continuum concept and his continuum base relativity theory, which were posthumously published in section "D" of “Appendix II” to the fifth edition of Einstein's book "The Meaning of Relativity":
"One can give good reasons why reality cannot at all be represented by a continuous field. From the quantum phenomena it appears to follow with certainty that a finite system of finite energy can be completely described by a finite set of numbers (quantum number). This does not seem to be in accord with a continuum theory, and must lead to an attempt to find a purely algebraic theory for the description of reality. But nobody knows how to obtain the basis of such a theory. (Einstein 1955, 166)" [8,12].

Conclusion
According to Stachel, "The Other Einstein [the one skeptical about the continuum as a foundational element in physics] had the last word" [8,9]. This means that by 1955, Einstein had concluded (1) relativity theory was not a fundamental theory and the continuum concept, along with space and time and differential quotients, had to be discarded (tossed out) as being fundamental, and (2) a discontinuum physics had to be developed for describing reality. Einstein was saying:
(1) Special relativity (SR) is not fundamental and must be replaced;
(2) Time dilation and length contraction are apparent, not real;
(3) Something is wrong with the system of measure used in SR and it must be fixed;
(4) Spacetime is not fundamental and must be replaced;
(5) General relativity (GR) is not fundamental and must be replaced;
(6) Gravity is a curvature of the replacement for spacetime, not a curvature of spacetime;
(7) Physical reality is not fundamental --- since (a) relativity theory gives an accurate description of physical reality, and (b) relativity theory is not fundamental, then it logically follows that the physical reality, which relativity theory accurately describes, cannot be fundamental either, and, just as relativity theory must be replaced by a more fundamental theory, which Einstein believes must be a discontinuum theory, physical reality must also be replaced by a more fundamental reality, which must be describable by the discontinuum theory.

References
[1] A. Einstein, "On the electrodynamics of Moving Bodies" in Ann. Phys. 17, 891 (1905).
Free copy at https://users.physics.ox.ac.uk/~rtaylor/teaching/specrel.pdf. Accessed 21 Oct. 2026.

[2] A. Einstein, "The Field Equations of Gravitation" in Prussian Academy of Sciences Proceedings (1915), part 4, pp. 844–847.
Free copy at https://en.wikisource.org/wiki/Translation:The_Field_Equations_of_Gravitation. Accessed 21 Oct. 2026.
Free copy at https://www.scribd.com/document/489556243/1915-Die-Feldgleichungen-der-Gravitation-Albert-Einstein-Konigl-Preu%C3%9F-Akad-der-Wissensch-Sitzung-am-25-11-1915. Accessed 21 Oct. 2026.

[3] A. Einstein, Albert. "Relativity: The Special and the General Theory." Translated by Robert W. Lawson, Henry Holt and Company, 1920. Elegant Books. pp. xi, xii, 98–102 (Chapter XXIV "Euclidean and Non-Euclidean Continuum"), 103–107 (Chapter XXV "Gaussian Co-ordinates"), 108–110 (Chapter XXVI "The Space-time Continuum of the Special Theory of Relativity considered as a Euclidean Continuum"), and 111–114 (Chapter XXVII "The Space-time Continuum of the General Theory of Relativity is not a Euclidean Continuum").
Free copy at https://www.ibiblio.org/ebooks/Einstein/Einstein_Relativity.pdf. Accessed 21 Oct. 2026.

[4] Center for Einstein Studies." Center for Philosophy & History of Science, Boston University. http://www.bu.edu/cphs/ces/. Accessed 21 Oct. 2026.

[5] "Research." Center for Einstein Studies, Center for Philosophy & History of Science, Boston University. http://www.bu.edu/cphs/ces/research/. Accessed 21 Oct. 2026.

[6] "John Stachel, Brief Curriculum Vitae." Center for Einstein Studies, Center for Philosophy & History of Science, Boston University. http://www.bu.edu/cphs/ces/research/john-stachel/. Accessed 21 Oct. 2026.

[7] "Papers and Presentations by Prof. Stachel." Center for Einstein Studies, Center for Philosophy & History of Science, Boston University. http://www.bu.edu/cphs/ces/research/papers-by-stachel/. Accessed 21 Oct. 2026.

[8] J. Stachel, Einstein from ‘B’ to ‘Z’ (Birkhauser Boston, c/o Springer-Verlag New York, Inc., NY, 2002), pp. 141-154.

[9] J. Stachel, Science in Context, Vol. 6, 1993, pp. 275-290; This is reprinted in reference [8].

[10] J. Stachel, "The Other Einstein." EinsteinFest, 23 Oct. 2005, Perimeter Institute, Waterloo, ON, Canada. Conference Presentation Slides. Boston University Center for Philosophy and History of Science. https://www.bu.edu/cphs/files/2015/04/2005_Conf_The_Other_Einstein.pdf. Accessed 21 Oct. 2026.

[11] A. Einstein, and N. Rosen. "The Particle Problem in the General Theory of Relativity" in Physical Review, vol. 48, no. 1, 1935, pp. 73–77.
Free copy at https://journals.aps.org/pr/pdf/10.1103/PhysRev.48.73. Accessed 21 Oct. 2026.

[12] A. Einstein, “The Meaning of Relativity” (Princeton University Press, Princeton, NJ, USA, 2005), pp. 165-166.
Free copy at https://lectures.princeton.edu/sites/g/files/toruqf296/files/2020- 08/_Albert_Einstein__Brian_Greene__The_meaning_of_rel_BookZZ.org_.pdf. Accessed 21 Oct. 2026.