The connection between physics teaching and research at its deepest level can be illuminated by physics education research (PER). For students and scientists alike, what they know and learn about physics is profoundly shaped by the conceptual tools at their command. Physicists employ a miscellaneous assortment of mathematical tools in ways that contribute to a fragmentation of knowledge. We can do better! Research on the design and use of mathematical systems provides a guide for designing a unified mathematical language for the whole of physics that facilitates learning and enhances physical insight. This research has produced a comprehensive language called geometric algebra, which I introduce with emphasis on how it simplifies and integrates classical and quantum physics. Introducing research-based reform into a conservative physics curriculum is a challenge for the emerging PER community. Join the fun!

1.
D.
Hestenes
, “
Who needs physics education research!?
Am. J. Phys.
66
,
465
467
(
1998
).
2.
The modeling instruction program is described at 〈http//modeling.asu.edu〉
3.
J. Piaget, To Understand is to Invent (Grossman, New York, 1973), pp. 15–20.
4.
D.
Hestenes
, “
Modeling games in the Newtonian world
,”
Am. J. Phys.
60
,
732
748
(
1992
).
5.
M.
Wells
,
D.
Hestenes
, and
G.
Swackhamer
, “
A modeling method for high school physics instruction
,”
Am. J. Phys.
63
,
606
619
(
1995
).
6.
K. Ericsson and J. Smith (eds.), Toward a General Theory of Expertise: Prospects and Limits (Cambridge U. P., Cambridge, 1991).
7.
A. Cromer, Connected Knowledge (Oxford, New York, 1997).
8.
L. Magnani, N. Nercessian, and P. Thagard (eds.), Model-Based Reasoning in Scientific Discovery (Kluwer Academic, Dordrecht, 1999).
9.
H.
Doerr
, “Integrating the study of trigonometry, vectors and force through modeling,” School Science and Mathematics 96, 407–418 (1996).
10.
D.
Hestenes
, “
Toward a modeling theory of physics instruction
,”
Am. J. Phys.
55
,
440
454
(
1987
).
11.
D. Hestenes, “Modeling methodology for physics teachers,” in The Changing Role of the Physics Department in Modern Universities, edited by E. Redish and J. Rigden (American Institute of Physics, Woodbury, NY, 1997), Part II, pp. 935–957.
12.
D. Hestenes, “Modeling software for learning and doing physics,” in Thinking Physics for Teaching, edited by C. Bernardini, C. Tarsitani, and M. Vincentini (Plenum, New York, 1996), pp. 25–66.
13.
A. Einstein, Ideas and Opinions (Three Rivers, New York, 1985), p. 274.
14.
H. Goldstein, Classical Mechanics, 2nd ed. (Addison-Wesley, Reading, MA, 1980).
15.
D. Hestenes, “Grassmann’s vision,” in Hermann Gunther Grassmann (1809–1877)—Visionary Scientist and Neohumanist Scholar, edited by G. Schubring (Kluwer Academic, Dordrecht, 1996), pp. 191–201.
16.
E.
Redish
and
G.
Shama
, “Student difficulties with vectors in kinematics problems,” AAPT Announcer 27, 98 (July 1997).
17.
D. Hestenes, “Mathematical viruses,” in Clifford Algebras and Their Applications in Mathematical Physics, edited by A. Micali, R. Boudet, and J. Helmstetter (Kluwer Academic, Dordrecht, 1991), pp. 3–16.
18.
D. Hestenes, New Foundations for Classical Mechanics (Kluwer, Dordrecht, 1986, 2nd ed., 1999).
19.
D. Hestenes, “Point groups and space groups in geometric algebra,” in Applications of Geometric Algebra in Computer Science and Engineering, edited by L. Doerst, C. Doran, and J. Lasenby (Birkhäuser, Boston, 2002), pp. 3–34.
20.
D.
Hestenes
, “
Multivector Functions
,”
J. Math. Anal. Appl.
24
,
467
473
(
1968
).
21.
D. Hestenes and G. Sobczyk, Clifford Algebra to Geometric Calculus: A Unified Language for Mathematics and Physics (Kluwer Academic, Dordrecht, 1986).
22.
D.
Hestenes
, “
Vectors, spinors and complex numbers in classical and quantum physics
,”
Am. J. Phys.
39
,
1013
1028
(
1971
).
23.
D. Hestenes, Space-Time Algebra (Gordon and Breach, New York, 1966).
24.
D.
Hestenes
, “
Real spinor fields
,”
J. Math. Phys.
8
,
798
808
(
1967
).
25.
D.
Hestenes
and
R.
Gurtler
, “
Local observables in quantum theory
,”
Am. J. Phys.
39
,
1028
1038
(
1971
).
26.
D.
Hestenes
, “
Spin and uncertainty in the interpretation of quantum mechanics
,”
Am. J. Phys.
47
,
399
415
(
1979
).
27.
C.
Doran
,
A.
Lasenby
,
S.
Gull
,
S.
Somaroo
, and
A.
Challinor
, “
Spacetime algebra and electron physics
,”
Adv. Imaging Electron. Phys.
95
,
271
365
(
1996
).
28.
D. Hestenes, “Differential forms in geometric calculus,” in Clifford Algebras and their Applications in Mathematical Physics, edited by F. Brackx, R. Delangke, and H. Serras (Kluwer Academic, Dordrecht, 1993), pp. 269–285.
29.
D. Hestenes, “Clifford algebra and the interpretation of quantum mechanics,” in Clifford Algebras and their Applications in Mathematical Physics, edited by J. S. R. Chisholm and A. K. Commo (Reidel, Dordrecht, 1986), pp. 321–346.
30.
F. Dyson, From Eros to Gaia (Pantheon Books, New York, 1992), Chap. 14.
31.
D. Hestenes, “ A unified language for mathematics and physics,” in Clifford Algebras and their Applications in Mathematical Physics, edited by J. S. R. Chisholm and A. K. Common (Reidel, Dordrecht, 1986), pp. 1–23.
32.
“The first conference proceedings on Clifford/Geometric Algebras,” in Clifford Algebras and their Applications in Mathematical Physics, edited by J. Chisholm and A. Common (Reidel, Dordrecht, 1986).
33.
D. Bohm, Quantum Theory (Prentice-Hall, Englewood Cliffs, NJ, 1951).
34.
T. Havel, D. Cory, S. Somaroo, and C.-H. Tseng, “Geometric algebra methods in quantum information processing by NMR spectroscopy,” in Geometric Algebra with Applications in Science and Engineering, edited by E. Bayro Corrochano and G. Sobczyk (Birkhäuser, Boston, 2001), pp. 281–308.
35.
R. Ablamowicz and B. Fauser (eds.), Clifford Algebras and their Applications in Mathematical Physics (Birkhäuser, Boston, 2000), Vols. 1 and 2.
36.
E. Bayro Corrochano and G. Sobczyk (eds.), Geometric Algebra with Applications in Science and Engineering (Bikhäuser, Boston, 2001).
37.
L. Doerst, C. Doran, and J. Lasenby (eds.), Applications of Geometrical Algebra in Computer Science and Engineering (Birkhäuser, Boston, 2002).
38.
T.
Vold
, “
An introduction to geometric algebra with an application to rigid body mechanics
,”
Am. J. Phys.
61
,
491
(
1993
);
T.
Vold
, “
An introduction to geometric calculus and its application to electrodynamics
,”
Am. J. Phys.
61
,
505
(
1993
).
39.
W. Baylis, Electrodynamics: A Modern Geometric Approach (Birkhäuser, Boston, 1999).
40.
A. Lasenby and C. Doran, Geometric Algebra for Physicists (Cambridge U. P., Cambridge, 2003).
41.
D.
Hestenes
, “The design of linear algebra and geometry,” Acta Applic. Math. 23, 65–93 (1991).
42.
C.
Doran
,
D.
Hestenes
,
F.
Sommen
, and
N.
Van Acker
, “
Lie groups as spin groups
,”
J. Math. Phys.
34
,
3642
3669
(
1993
).
This content is only available via PDF.
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.