We discuss the experimental consequences of hypothetical time variations of the fundamental constants. We show that any observed time variations can be interpreted as being due to changes in the dimensionless fundamental constants, once the effects of the constants on the structure of the experiment are taken into account. Young’s experiment for a slow charged particle and a version of the twin paradox are discussed to show how their results are independent of physical constants. We also show that experiments that are generally interpreted in terms of time variations of the gravitational constant are better interpreted as giving limits on the variation of the dimensionless constant where is the mass of the proton.
REFERENCES
1.
J. K.
Webb
et al., “Further evidence for cosmological evolution of the fine structure constant
,” Phys. Rev. Lett.
87
, 091301
–4
(2001
).2.
A recent review of limits on time variations of the fundamental constants is given by
Jean-Philippe
Uzan
, “The fundamental constants and their variation: Observational status and theoretical motivations
,” hep-ph/0205340.3.
M.
Maurette
, “Fossil nuclear reactors
,” Annu. Rev. Nucl. Sci.
26
, 319
–350
(1976
).4.
A. I.
Shlyakhter
, “Direct test of the constancy of fundamental nuclear constants
,” Nature (London)
264
, 340
(1976
).5.
J.
Magueijo
, J. D.
Barrow
, and H. B.
Sandvik
, “Is it e or is it c? Experimental tests of varying alpha
,” Phys. Lett. B
549
, 284
–289
(2002
).6.
7.
M. J.
Duff
, L. B.
Okun
, and G.
Veneziano
, “Trialogue on the number of fundamental constants
,” J. High Energy Phys.
03023
, 1
–30
(2002
) and physics/0110060.8.
9.
10.
A. H.
Cook
, “Secular changes of the units and constants of physics
,” Nature (London)
180
, 1194
–1195
(1957
).11.
J. P. Turneaure and S. R. Stein, “An experimental limit on the time variation of the fine structure constant,” in Atomic Masses and Fundamental Constants 5, edited by J. H. Sanders and A. H. Wapstra (Plenum, New York, 1976), pp. 636–642.
This content is only available via PDF.
© 2003 American Association of Physics Teachers.
2003
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.