New Scientist
183.2457 (July 24,
2004). Available online at http://www.new scientist.com/article.ns?id=dn6189.
71.
T. L. Wilson, "The Search for Extraterrestrial Intelligence,"
Nature
, February 22, 2001.
72.
Most recent estimates have been between ten and fifteen billion years. In 2002 estimates based on
data from the Hubble Space Telescope were between thirteen and fourteen billion years. A study
published by Case Western Reserve University scientist Lawrence Krauss and Dartmouth
University's Brian Chaboyer applied recent findings on the evolution of stars and concluded that
there was a 95 percent level of confidence that the age of the universe is between 11.2 and 20
billion years. Lawrence Krauss and Brian Chaboyer, "Irion, the Milky Way's Restless Swarms of
Stars,"
Science
299 (January 3, 2003): 60–62. Recent research from NASA has narrowed down the
age of the universe to 13.7 billion years plus or minus 200 million,
http://map.gsfc.nasa.gov/m_mm/mr_age.html.
73.
Quoted in Eric M. Jones, " 'Where Is Everybody?': An Account of Fermi's Question," Los Alamos
National Laboratories, March 1985,
http://www.bayarea.net/~kins/AboutMe/Fermi_and_Teller/fermi_ question.html.
74.
First, consider the estimate of 10
42
cps for the ultimate cold laptop (as in chapter 3). We can
estimate the mass of the solar system as being approximately equal to the mass of the sun, which is
2 x 10
30
kilograms. One twentieth of 1 percent of this mass is 10
27
kilograms. At 10
42
cps per
kilogram, 10
27
kilograms would provide 10
69
cps. If we use the estimate of 10
50
cps for the ultimate
hot laptop, we get 10
77
cps.
75.
Anders Sandberg, "The Physics of Information Processing Superobjects: Daily Life Among the
Jupiter Brains,"
Journal of Evolution and Technology
5 (December 22, 1999),
http://www.jetpress.org/volume5/Brains2.pdf.
76.
Freeman John Dyson, "Search for Artificial Stellar Sources of Infrared Radiation,"
Science
131
(June 3,1960): 1667–68.
77.
Cited in Sandberg, "Physics of Information Processing Superobjects."
78.
There were 195.5 billion units of semiconductor chips shipped in 1994, 433.5 billion in 2004. Jim
Feldhan, president, Semico Research Corporation, http://www.semico.com.
79.
Robert Freitas has been a leading advocate of using robotic probes, especially self-replicating ones.
See Robert A. Freitas Jr., "Interstellar Probes: A New Approach to SETI,"
J. British Interplanet.
Soc.
33 (March 1980): 95–100, http://www.rfreitas.com/Astro/lnterstellarProbesJBIS1980.htm;
Robert A. Freitas Jr., "A Self-Reproducing Interstellar Probe,"
J. British Interplanet. Soc.
33 (July
1980): 251–64, http://www.rfreitas.com/Astro/ReproJBISJuly1980.htm; Francisco Valdes and
Robert A. Freitas Jr., "Comparison of Reproducing and Nonreproducing Starprobe Strategies for
Galactic Exploration,"
J. British Interplanet. Soc.
33 (November 1980): 402–8,
http://www.rfreitas.com/Astro/ComparisonReproNov1980.htm; Robert A. Freitas Jr., "Debunking
the Myths of Interstellar Probes,"
AstroSearch
1 (July–August 1983): 8–9,
http://www.rfreitas.com/Astro/ProbeMyths1983.htm; Robert A. Freitas Jr., "The Case for
Interstellar Probes,"
J. British Interplanet. Soc.
36 (November 1983): 490–95,
http://www.rfreitas.com/Astro/TheCaseForInterstellarProbes1983.htm.
80.
M. Stenner et al., "The Speed of Information in a 'Fast-Light' Optical Medium,"
Nature
425
(October 16, 2003): 695–98. See also Raymond Y. Chiao et al., "Superluminal and Parelectric
Effects in Rubidium Vapor and Ammonia Gas,"
Quantum and Semiclassical Optics
7 (1995): 279.
81.
I. Marcikic et al., "Long-Distance Teleportation of Qubits at Telecommunication Wavelengths,"
Nature
421 (January 2003): 509–13; John Roach, "Physicists Teleport Quantum Bits over Long
Distance,"
National Geographic News
, January 29, 2003; Herb Brody, "Quantum Cryptography; in
"10 Emerging Technologies That Will Change the World,"
MIT Technology Review
, February
2003; N. Gisin et al., "Quantum Correlations with Moving Observers,"
Quantum Optics
(December
2003): 51; Quantum Cryptography exhibit, ITU Telecom World 2003, Geneva, Switzerland,
October 1, 2003; Sora Song, "The Quantum Leaper,"
Time
, March 15, 2004; Mark Buchanan,
"Light's Spooky Connections SetNew Distance Record,"
New Scientist
, June 28, 1997.
82.
Charles H. Lineweaver and Tamara M. Davis, "Misconceptions About the Big Bang,"
Scientific
American
, March 2005.
83.
A. Einstein and N. Rosen, "The Particle Problem in the General Theory of Relativity,"
Physical
Review
48 (1935): 73.
84.
J. A. Wheeler, "Geons,"
Physical Review
97 (1955): 511–36.
85.
M. S. Morris, K. S. Thorne, and U. Yurtsever, "Wormholes, Time Machines, and the Weak Energy
Condition,"
Physical Review Letters
61.13 (September 26, 1988): 1446–49; M. S. Morris and K. S.
Thorne, "Wormholes in Spacetime and Their Use for Interstellar Travel: A Tool for Teaching
General Relativity,"
American Journal of Physics
56.5 (1988): 395–412.
86.
M. Visser, "Wormholes, Baby Universes, and Causality,"
Physical Review D
41.4 (February 15,
1990): 1116–24.
87.
Sandberg, "Physics of Information Processing Superobjects."
88.
David Hochberg and Thomas W. Kephart, "Wormhole Cosmology and the Horizon Problem,"
Physical Review Letters
70 (1993): 2665–68, http://prola.aps.org/abstract/PRL/v70/i18/p2665_1; D.
Hochberg and M. Visser, "Geometric Structure of the Generic Static Transversable Wormhole
Throat,"
Physical Review D
56 (1997): 4745.
89.
J. K. Webb et al., "Further Evidence for Cosmological Evolution of the Fine Structure Constant,"
Physical Review Letters
87.9 (August 27, 2001): 091301; "When Constants Are Not Constant,"
Physics in Action
(October 2001), http://physicsweb.org/articles/world/14/10/4.
90.
Joao Magueijo, John D. Barrow, and Haavard Bunes Sandvik, "Is It e or Is It c? Experimental Tests
of Varying Alpha,"
Physical Letters B
549 (2002): 284–89.
91.
John Smart, "Answering the Fermi Paradox: Exploring the Mechanisms ofUniversal Transcension,"
http://www.transhumanist.com/Smart-Fermi.htm. See also http://singuIaritywatch.com and his
biography at http://www.singuIaritywatch.com/bio_johnsmart.html.
92.
James N. Gardner,
Biocosm: The New Scientific Theory of Evolution: Intelligent Life Is the
Architect of the Universe
(Maui: Inner Ocean, 2003).
93.
Lee Smolin in "Smolin vs. Susskind: The Anthropic Principle,"
Edge
145,
http://www.edge.org/documents/archive/edge145.html; Lee Smolin, "Scientific Alternatives to the
Anthropic Principle," http://arxiv.org/abs/hep-th/0407213.
94.
Kurzweil,
Age of Spiritual Machines
, pp. 258–60.
95.
Gardner,
Biocosm
.
96.
S. W. Hawking, "Particle Creation by Black Holes,"
Communications in Mathematical Physics
43
(1975): 199–220.
97.
The original bet is located at http://www.theory.caltech.edu/people/preskill/info_bet.html. Also see
Peter Rodgers, "Hawking Loses Black Hole Bet,"
Physics World
, August 2004,
http://physicsweb.org/articles/news/8/7/11.
98.
To arrive at those estimates Lloyd took the observed density of matter—about one hydrogen atom
per cubic meter—and computed the total energy in the universe. Dividing this figure by the Planck
constant, he got about 10
90
cps. Seth Lloyd, "Ultimate Physical Limits to Computation,"
Nature
406.6799 (August 31, 2000): 1047–54. Electronic versions (version 3 dated February 14, 2000)
available at http://arxiv.org/abs/quant-ph/9908043 (August 31, 2000). The following link requires a
payment to access: http://www.nature.com/cgi-
taf/DynaPage.taf?file=/nature/journal/v406/n6799/full/4061047a0_fs.html&content_filetype=PDF.
99.
Jacob D. Bekenstein, "Information in the Holographic Universe: Theoretical Results about Black
Holes Suggest That the Universe Could Be Like a Gigantic Hologram,"
Scientific American
289.2
(August 2003): 58–65, http://www.sciam.com/article.cfm?articleID=000AF072-4891-1F0A-
97AE80A84189EEDF.
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