It has been well known since the pioneering work of Claude Shannon in the 1940s that a message transmitted with optimal efficiency over a channel of limited bandwidth is indistinguishable from random noise to a receiver who is unfamiliar with the language in which the message is written. We derive some similar results about electromagnetic transmissions. In particular, we show that if electromagnetic radiation is used as a transmission medium, the most information-efficient format for a given message is indistinguishable from blackbody radiation. The characteristic temperature of the radiation is set by the amount of energy used to make the transmission. If information is not encoded in the direction of the radiation, but only in its timing, energy, and polarization, then the most efficient format has the form of a one-dimensional blackbody spectrum.

1.
C. E. Shannon and W. Weaver, The Mathematical Theory of Communication (University of Illinois Press, Urbana, 1949).
2.
T. M. Cover and J. A. Thomas, Elements of Information Theory (Wiley, New York, 1991).
3.
E. T. Jaynes, Papers on Probability, Statistics and Statistical Physics (Reidel, Dordrecht, 1983).
4.
W. T. Grandy, Foundations of Statistical Mechanics (Reidel, Dordrecht, 1987).
5.
V.
Giovannetti
,
S.
Lloyd
,
L.
Maccone
, and
J. H.
Shapiro
, “
Information rate of a waveguide
,” quant-ph/0307112.
6.
W. D. Smith, “Fundamental physical limits on computation” (unpublished, 1995).
7.
J. D.
Bekenstein
and
M.
Schiffer
, “
Quantum limitations on the storage and transmission of information
,”
Int. J. Mod. Phys. C
1
,
355
422
(
1990
).
8.
C. M.
Caves
and
P. D.
Drummond
, “
Quantum limits on bosonic communication rates
,”
Rev. Mod. Phys.
66
,
481
537
(
1994
).
9.
D. S.
Lebedev
and
L. B.
Levitin
, “
The maximum amount of information transmissible by an electromagnetic field
,”
Sov. Phys. Dokl.
8
,
377
379
(
1963
).
10.
J. B.
Pendry
, “
Quantum limits to the flow of information and entropy
,”
J. Phys. A
16
,
2161
2171
(
1983
).
11.
H. P.
Yuen
and
M.
Ozawa
, “
Ultimate information carrying limit of quantum systems
,”
Phys. Rev. Lett.
70
,
363
366
(
1993
).
12.
J. D.
Bekenstein
, “
Black holes and information theory
,”
Contemp. Phys.
45
,
31
43
(
2004
).
13.
S. W.
Hawking
, “
Particle creation by black holes
,”
Commun. Math. Phys.
43
,
199
220
(
1975
).
14.
I. Stewart and J. Cohen, Wheelers (Warner Aspect, New York, 2001).
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.