The concept of gravity came into being in ancient times as a terrestrial concern associated with the practicalities of “weight.” A great leap forward came in the early 1600s with the important theoretical speculations of Johannes Kepler. This article focuses on his prescient theory of gravity which guided the later progress of a number of scholars including Roberval, Hooke, and Newton. And yet, Kepler's remarkable contribution to gravitational theory has been almost completely overlooked in the contemporary scientific literature.
References
1.
Gerald
Holton
, “Johannes Kepler's universe: Its physics and metaphysics
,” Am. J. Phys.
24
, 340
–351
(1956
).2.
James T.
Cushing
, “Kepler's laws and universal gravitation in Newton's Principia
,” Am. J. Phys.
50
, 617
–628
(1982
). This fine paper, like so many others, makes no mention of Kepler's theory of gravity.3.
Eugene
Hecht
, “Kepler and the origins of pre-Newtonian mass
,” Am. J. Phys.
85
, 115
–123
(2017
).4.
5.
6.
For an English translation of Commentariolus see <http://dbanach.com/copernicus-commentarilous.htm>
7.
Anton
Postl
, “Kepler's Anniversary
,” Am. J. Phys.
40
, 660
–666
(1972
). This paper provides a highly readable history of Kepler's life and works, although it overlooks his theory of gravity completely.8.
9.
Reference 5, Part 7; Book II.
10.
Reference 4, p.
31
.11.
12.
13.
Reference 12, p.
74
.14.
Nicolaus
Copernicus
, “On the revolutions of the heavenly spheres,” in Great Books of the Western World
(Encyclopedia Britannica
, Chicago
, 1948
), p. 521
.15.
William
Gilbert
, On the Magnet, trans. by Silvanus Thompson (1900
). http://www.gutenberg.org/files/33810/33810-h/33810-h.htm or <http://www.worldcat.org/title/de-magnete/oclc/3212592/viewport>. The Latin original of De Magnete can be found at <http://www.scribd.com/doc/299316581/Gilbert-De-Magnete-Latino>.16.
Reference 4, p.
20
.17.
Reference 15, Book 2, Chap. II.
18.
Reference 15, Book 2, Chap. I.
19.
Reference 15, Book 2, Chap. XVI.
20.
Reference 15, Book 6, Chap. III.
21.
Reference 15, Book 6, Chap. V.
22.
Reference 15, Book 6, Chap. VI.
23.
24.
Max
Casper
, Kepler
(Collier Books
, NY
, 1962
), p. 47
. For a corrected and expanded edition see Kepler (Dover Publications, NY, 1993).25.
Charles
Gillispie
, Dictionary of Scientific Biography
(Charles Scribner's Sons
, NY
, 1973
), p. 289
.26.
27.
Hans
Blumenberg
, The Genesis of the Copernican World
(MIT Press
, Cambridge, MA
, 1987
), p. 248
.28.
Johannes
Kepler
, Mysterium Cosmographicum, The Secret of the Universe
, trans. by A. M.
Duncan
(Abaris Books
, NY
, 1981
), p. 75
(in Latin), p. 199 (in English).29.
Dorothea W.
Singer
, Giordano Bruno, His Life and Thought
(Abeard-Schuman, Inc.
, NY
, 1950
).30.
Reference 24, p.
71
.31.
Reference 28, footnote 3, p. 202. See also,
Arthur
Koestler
, The Sleep Walkers
(The Macmillan Company
, NY
, 1959
), p. 259
. This is my translation.32.
Reference 27, p.
142
.33.
Reference 24, Dover Publications p. 139, footnote. See also
M.
Casparand
W.
von Dyck
, Johannes Kepler Gesammelte Werke, in Latin at <http://kepler.badw.de/kepler-digital.html> where it appears in Vol. XV, p. 241
.34.
Reference 33, Gesammelte Werke, Epitome of Copernican Astronomy. In Latin at <http://kepler.badw.de/kepler-digital.html> where it appears in Vol. VII, p.
93
.35.
Edward
Rosen
, Kepler's Somnium
(University of Wisconsin Press
, Madison
, 1967
), p. 159
. <https://www.loc.gov/resource/rbctos.2017gen10144/?sp=1>. The necessity for a grasping force may have come from Kepler's conviction that “the motions of heavy bodies are rectilinear, so that this kind of order, I mean [motion in] a straight line, is somehow a property of heavy bodies…” The implications for the Law of Inertia are obvious.36.
Reference 33, Gesammelte Werke. My translation. In Latin at <http://kepler.badw.de/kepler-digital.html> where it appears in Vol. XV, p.
240
.37.
See also,
Johannes
Kepler
, Astronomia Nova
, trans. by William
Donahue
(Green Lion Press
, NM
, 2015
), p. 24
, footnote. In Latin at <https://archive.org/details/Astronomianovaa00Kepl>. Also in Latin at <http://kepler.badw.de/kepler-digital.html> where it appears in Vol. III.38.
William
Donahue
, Selections From Kepler's Astronomia Nova
(Green Cat Books
, NM
, 2008
), p. 12
. Alternatively see Ref. 37, p. 24. Donahue provides an extensive discussion of the many meanings of the Latin word species. Here, as was done by A. M. Duncan, it will be translated as “emanation.”39.
40.
Johannes
Kepler
, Epitome of Copernican Astronomy & Harmonies of the World
, Books IV and V (1618–1621), translated by Charles
Wallis
(Prometheus Books
, NY
, 1995
). Books I to III on line in Latin at <https://books.google.com/books?id=KUE1AAAAcAAJ&printsec=frontcover&source=gbs_ge_summary_r&cad=0#v=onepage&q&f=false>. Also in Latin at <http://kepler.badw.de/kepler-digital.html> where it appears in Vol. VII.41.
Reference 40, p.
130
.42.
Reference 40, p.
175
.43.
Reference 40, p.
63
.44.
45.
Reference 40, p.
130
.46.
Reference 35, Appendix H provides a summary of several aspects of Kepler's theory of gravity. For the complete Latin original of Somnium view online: <https://archive.org/stream/joanniskepleria00frisgoog#page/n8/mode/2up>.
47.
48.
Reference 35, p.
74
.49.
Reference 35, Note 66, p.
71
.50.
Reference 29, third dialogue, p.
303
.51.
Reference 35, Note 202, p.
123
.52.
Edward
Rosen
, “Kepler's harmonics and his concept of inertia
,” Am. J. Phys.
34
, 610
–613
(1966
). Rosen's last paragraph claiming inertial motion, is a bit of a distortion of the physics of the situation as described by Kepler in Notes 74, 75, and 76.53.
Reference 40, p.
92
.54.
Epitome Astronomiae Copernicanae, Book IV, p.
517
, of the first edition. This was published as a separate volume in 1622, four years after Books I–III. Hence it is Vol. 2, though paginated continuously from Vol. 1. It can be viewed on line in Latin at <http://kepler.badw.de/kepler-digital.html> where it appears in Vol. VII on p. 300; or <http://archive.org/details/bub_gb_FaMM9-9BkkgC> (My translation).55.
Pierre
de Fermat
, Oeuvres
, edited by P.
Tannery
and C.
Henry
(Gauthier-Villars
, Paris
, 1894
), Vol. 2
, p. 36
. See also Ref. 8, Jammer, p. 92.56.
Thomas
Birch
, The History of the Royal Society of London for the Improving of Nature
(A. Millar in the Strand
, London
, MDCCLVI), p. 70
.57.
Robert D.
Purrington
, The First Professional Scientist
(Birkhäuser
, Basel, Switzerland
, 2009
), p. 168
.© 2019 American Association of Physics Teachers.
2019
American Association of Physics Teachers
AAPT members receive access to the American Journal of Physics and The Physics Teacher as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.
