The paper on “Magnetism and Simultaneity” by Adler1 provides an excellent new thought experiment involving the lack of simultaneity in Einstein's special relativity. Adler uses the lack of simultaneity rather than the Lorentz contraction2 to derive the formula for the magnetic force on a moving charged particle. Advantages of his derivation are that the algebra is simpler and the results more general than our derivation based on the Lorentz contraction.
REFERENCES
1.
Charles
Adler
, “Magnetism and simultaneity
,” Phys. Teach.
47
, 221
–223
(April 2009
).2.
Elisha
Huggins
and Drew
Milson
, “Lorentz transformation and charge conservation
,” letter to the editor, Phys. Teach.
45
, 328
–329
(Sept. 2007
).3.
We introduced the use of the laser and beam splitter in
Huggins
, “On teaching the lack of simultaneity
,” Am. J. Phys.
43
, 599
–600
(1975
). There we also describe how to pull an uncontracted rocket ship in through a contracted barn door.4.
More applications of the laser and beam splitter approach can be found in the free pamphlet “Teaching Relativity in Week One,” which is available for download at www.physics2000.com.
This content is only available via PDF.
© 2009 American Association of Physics Teachers.
2009
American Association of Physics Teachers
AAPT members receive access to The Physics Teacher and the American Journal of Physics as a member benefit. To learn more about this member benefit and becoming an AAPT member, visit the Joining AAPT page.
