by J. Deardorff, B. Haisch, B. Maccabee and
JBIS, Vol. 58, pp. 43-50
It has recently been argued that anthropic reasoning applied to
inflation theory reinforces the prediction that we should find
ourselves part of a large, galaxy-sized civilization, thus
strengthening Fermi's paradox concerning "Where are they?"
Furthermore, superstring and M-brane
theory allow for the possibility of parallel universes, some of
which in principle could be habitable. In addition, discussion of
such exotic transport concepts as "traversable wormholes" now
appears in the rigorous physics literature.
As a result, the "We are alone" solution
to Fermi's paradox, based on the constraints of earlier 20th century
viewpoints, appears today to be inconsistent with new developments
in our best current physics and astrophysics theories.
reexamine and reevaluate the present assumption that
extraterrestrials or their probes are not in the vicinity of Earth,
and argue instead that some evidence of their presence might be
found in certain high-quality UFO reports.
This study follows up on previous
(1) interstellar travel for advanced
civilizations is not a priori ruled out by physical principles
and therefore may be practicable
(2) such advanced civilizations may
value the search for knowledge from uncontaminated species more
than direct, interspecies communication, thereby accounting for
apparent covertness regarding their presence
The ever recurring question of why Earth has seemingly not been
visited by extraterrestrials (ETs) has received
considerable discussion under the topic of 'Fermi's paradox'.
originated as a quip by Enrico Fermi to colleagues in Los Alamos
over lunch one day in 1950.
Whether one assumes the existence of
only one other civilization or of many alien civilizations in our
Milky Way galaxy, and whether one assumes colonization involving
interstellar travel at near-light speed or far below, diffusion
modeling predicts colonization or at least visitation of all
habitable planets in the galaxy on timescales of tens of millions of
years, far less than the approximate 13 x 109 year age of the galaxy
Thus the paradox: Where are they?
Theoretical possibilities unknown to Fermi make the paradox even
stronger today. One can now rationally conjecture about prospects
afforded by adjacent M-brane universes. 
Indeed, if the
multidimensions underlying superstring and M-brane theory are
correct, there could be inhabited universes separated from our own
by minute, orthogonal distances.
Also, anthropic reasoning has
recently been applied to inflation theory, arriving once again at
the conclusion that we should find ourselves within an enormously
larger galactic civilization. 
While the 'We are alone' solution to
Fermi's paradox was once a seemingly valid one, this answer is now
incompatible with the infinite universe and random self-sampling
assumption consistent with inflation theory.
We thus find ourselves
in the curious position that current cosmological theory predicts
that we should be experiencing extraterrestrial visitation.
same time, current physics and astrophysics suggest that such
visitation may not be as impossible as had been thought.
In recent astronomical discoveries, over 100
exoplanets have been
catalogued, with detection sensitivity now increased to the point
where, in one instance, a Jupiter-sized planet was deduced to be in
a Jupiter-like orbit around a Sol-like star. 
In the field of
exobiology, much recent activity suggests that some of the building
blocks for life may originate in space as well as be transported by
The possibility of widespread
has received new impetus. [7-8]
These findings and studies make
plausible the hypothesis that there is intelligent life elsewhere in
the universe. This is, of course, the fundamental assumption made by
the proponents of SETI, the Search for Extraterrestrial Intelligence
using microwave or optical means of detection.
The extraterrestrial hypothesis (ETH), that intelligent life from
'elsewhere' in the universe could be visiting Earth, has become less
implausible through suggestions that the velocity-of-light
constraint - 'they can't get here from there' - is not as restricting
as had been assumed previously.
This restriction has its origin in the
special theory of relativity, which we do not question. However,
within the context of general relativity (GR) there are three
approaches which may permit legitimately bypassing this limit, given
sufficiently advanced (perhaps by millions of years!) knowledge of
physics and technology.
One approach popularized by Thorne and Sagan concerns the
possibility of wormholes, or cosmic subways, a form of shortcut
through the space-time metric. 
Using the standard GR as a basis,
certain mathematical requirements for traversable worm-holes have
been derived and published in the scientific literature and it
appears that there is the possibility of engineering a wormhole
metric, at least in principle. 
A second more recent approach published in the GR literature has
been dubbed the 'Alcubierre Warp Drive'. [11-12]
Unlike the speed of
light limit through space, there is no limit to the speed at which
space itself might stretch. Faster than light (FTL) relative motion
is part of inflation theory, and presumably the universe beyond the
Hubble distance is receding from us faster than c.
It was shown that a spaceship contained
in a volume of Minkowski space could in principle make use of FTL
expansion of space-time behind and a similar contraction in front,
with the inconvenience of time dilation and untoward accelerations
being overcome. A related approach involves constructing a 'Krasnikov tube'
 to connect spatially remote locales.
so-called exotic matter would be required for either case.
If GR itself were to be reinterpreted in terms of a polarisable
vacuum as first proposed by Dicke,  this would open the
possibility of a different type of metric engineering in which the
dielectric properties of the vacuum might be altered in such a way
as to raise the local propagation velocity of light.
In effect one
would be creating a local index of refraction of less than unity.
Finally, there is the conjectured possibility of making use of the
additional dimensionalities of M-brane and superstring theory to
transfer into adjacent universes where the speed of light limit may
be quite different and reentering our universe at the desired
location. This is by far the most speculative possibility.
Clearly when it comes to engineering warp drive or wormhole
solutions, seemingly insurmountable obstacles emerge, such as
unattainable energy requirements  or the need for exotic matter.
Thus, if success is to be achieved, it must rest on some yet
unforeseen breakthrough about which we can only speculate, such as a
technology to cohere otherwise random vacuum fluctuations.
Nonetheless, the possibility of
reduced-time interstellar travel by advanced extraterrestrial (ET)
civilizations is not, as naive consideration might hold,
fundamentally ruled out by presently known physical principles. ET
knowledge of the physical universe may comprise new principles which
allow some form of FTL travel.
This possibility is to be taken
seriously, since the average age of suitable stars within the 'galactic habitable zone', in which the Earth also resides, is found
to be about 109 years older than the sun  suggesting the
possibility of civilizations extremely advanced beyond our own.
There are further reasons why the 'We are alone' solution to Fermi's
paradox should perhaps be set aside in favor of the ETH.
previously preferred solution, that biogenesis is an exceedingly
rare event in conjunction with both panspermia and interstellar
travel being inoperative,  is now scarcely tenable in light of
the cosmological considerations already discussed.
The ETH appears to be the most viable
remaining solution, where 'ET' is taken in a general non-Earthly
sense that could include extra-dimensional realms, as in M-brane and
Given the highly advanced ET science and
technology to be expected in considerably older civilizations,
coupled with the many observational reports since WWII of highly
advanced technology seemingly operating at will within Earth's
skies, it is only logical to search for evidence of ET visitations
in at least a fraction of the ongoing, unexplainable re-ports
popularly referred to as 'UFO sightings.'
Reluctance to do so could result in our
failure to realize that observations of 'genuine' ET visitations
have been occurring.
This approach, which we follow here, explores
the likelihood that 'we actually do belong to a large civilization
but are unaware of that fact'. 
3. U.S. Air
Reports of unknown objects in the skies,
appearing as some sort of flying craft and exhibiting extraordinary
maneuvers, first became known to the general public in 1947.
first publicized sighting occurred on June 24 of that year, after
which there were many hundreds of sightings during the following
The phenomenon has been continuing ever since.
At first the U.S. Air Force collected
the sighting reports for analysis in its operation
(1948-1949). This was succeeded by
Project Grudge (1949-1952) and
Project Blue Book (1952-1969).
Some 20% of Project Blue
Book's sightings from 1953-1965 were left unexplained, if their 'insuf-ficient data' category is included.
The Battelle Memorial Institute (BMI;
Columbus, Ohio) discovered, in their study of 3,201 reports from
1947 through 1952, that the percentage of unknowns (unexplainable
sightings) increased with increasing quality of the sighting
information and reliability of the observers. 
A surprisingly high percentage, 30%, of
the civilian sightings, and an even more surprising 38%, of the
military sightings rated as excellent in quality were listed as
On the other hand, only about 15% of the civilian and 20%
of the military sightings rated as poor were unknown.
in the percentage of unknowns with increasing quality of the report
is an unexpected result if sightings were all explainable as
mistakes (failure to correctly identify the sighted phenomenon) by
either the observer(s) or the scientists who analyzed the sightings.
In this collection of 3,201 sightings none were listed as hoaxes and
only 1.5% were listed as caused by psychological effects.
This result discovered during the
several year long BMI study refutes the claim, made in
Report,  that UFO reports are from
'less well informed
individuals,' who are 'not necessarily reliable.'
It is worthy of
note that Condon had access to the results of the BMI study but
there is no reference to it in the Condon Report.
Project Blue Book culminated in 1969 with the government sponsored
Condon Report. In the opening section of the Report its
director concluded that, after years of investigation, the U.S. Air
Force had found nothing truly new - nothing that supported claims of
new physics or the ETH - and that continued investigation probably
would not find anything truly new in the future.
recommended that the Air Force end its investigation project, which
it did in late 1969.
4. The Condon Report
In the late 1960's, the U.S. Air Force issued a con-tract to the
University of Colorado to carry out a scientific study of evidence
concerning the UFO phenomenon.
The director of the project was Prof.
Edward U. Condon, a distinguished and influential physicist who made
no secret of his opinion even at the outset that no substantive
evidence for extraterrestrial visitation was liable to result.
The study was relatively brief (2 years)
and had a notably low budget (app. $500K) for a serious scientific
When the Condon Report was released in 1968, the American
scientific community accepted its apparently negative conclusion
concerning evidence for extraterrestrial visitation in a generally
uncritical way, and to some extent even an enthusiastic way since it
offered an end to a troublesome situation.
An endorsement of the Report by the
National Academy of Sciences took place following an unusually rapid
review and the Air Force quickly used the Report as a justification
to terminate any further public involvement with the topic.
The negative conclusion of the Report is more apparent than real
however, since there is a substantial discrepancy between the
conclusion in the "Summary of the Study" written by Condon
single-handedly, and the conclusion one could reasonably draw from
the evidence presented in the main body of the Report.
Such a dichotomy was possible be-cause
the study was a project for which the director, Condon, had sole
authority; it was not the work of a committee whose members would
have to reach some consensus conclusion.
An analysis of the Condon
Report by Sturrock  details the many disagreements between
Condon's dismissive summary and the actual data.
Given the thousand-page length of the Report, one can safely assume
that very few in the scientific community would have devoted the
time necessary to read the entire document.
The impact of the
Report was thus largely due to Condon's leveraging his prestigious
scientific reputation into an acceptance of his own personal views
as representing the apparent outcome of a scientific investigation.
Indeed, as Sturrock documents, Condon actually took no part in the
investigations and indicated the conclusion he intended to draw well
before the data were properly examined, hardly a scientific
The portion of the Condon Report that contains its sighting analyses
does not support the "Summary of the Study" written by Condon.
Many of the events presented within its Case Studies section do fall
into the 'unidentified' category of UFOs, for which the Report's
definition was, in essence:
'A puzzling stimulus for a report of
something seen in the sky or landed on the earth that could not
be identified as having an ordinary natural origin.'
In a detailed review of this Report,
however, it was noted that,
'The sheer bulk of the report, much
of it "scientific padding", cannot conceal from anyone who
studies it closely that it examines only a tiny fraction of the
really puzzling UFO reports, and that its scientific
argumentation is often unsatisfactory.
Of roughly ninety cases
that it specifically confronts, more than thirty are conceded to
be unexplained'. 
Four of the cases, reanalyzed and
reported in detail at the 1969 AAAS Symposium, disclosed how
unscientific the Condon Report's treatment of them had been; the
reanalyzes have since gone unrefuted.
Hence we cannot agree with the
Condon Report's assertion that the phenomenon pro-vides no new
subjects for science to explore, given that many sightings were left
Furthermore, in many of the cases that
the Report claimed to have identified, that goal was achieved merely
through assuming that the witnesses had seen some-thing differing in
detail from what they had reported.
Also, a committee of the
American Institute of Aeronautics and Astronautics in 1971 found
difficult to ignore the small residue of well-documented but
un-explainable cases that form the hard core of the UFO
Clearly, the Condon Report was left in an
unsatisfactory state. [20, 24-26, 29-30]
The primary conclusion of the Condon panel side-stepped the main
issue, the failure to explain every sighting, by saying:
evidence presented on Unidentified Flying Objects shows no
indication that these phenomena constitute a direct physical threat
to national security'. 
This is not inconsistent, however, with
some fraction of unexplained reports representing actual ET
Re-Evaluation of the Phenomenon Needed
5.1 Sightings Since the Condon
The self-inconsistency of the Condon Report, along with the
strengthening of Fermi's paradox through recent developments in
cosmology, physics, astronomy and astrobiology, are but two
reasons to reevaluate the UFO phenomenon.
Another reason is that
remarkable sightings did not cease with the publication of the
Condon Report in 1969. Many detailed sightings since then have
become available for examination.
Scientists should not feel reluctant
to study these inasmuch as the Report's executive summary stated
that 'any scientist with adequate training and credentials who
does come up with a clearly defined, specific proposal for study
[of UFO reports] should be supported.'
One example of sightings worth studying are those that occurred
on December 31, 1978 off the north-east coast of South Island,
These involved several channels of information
recorded on tape and film during the sightings, correlated
visual air- and ground-radar detections and light phenomena
recorded on color movie film as well as reports by the eight
witnesses who were involved.
Analysis of the recorded data and of
the witness testimony indicates that unknown objects emitting
bright light were detected on radar, filmed and apparently moved
in response to the motions of the airplane carrying the
witnesses. The sightings have defied all mundane explanations
Some investigations of unexplainable sightings have been
sponsored by governments outside the
U.S. Since 1977 the French Space Agency has carried out an
official investigation of UFO reports with its project GEPAN,
later called SEPRA.
In the Belgium sighting wave of 1989-90,
civilian and military officials cooperated in sharing
eyewitness, radar and video-image data of triangular-shaped
5.2 Withheld Information Now Available
The Condon investigators did not have full access to the
information and analysis compiled previously by the U.S. Air
Force Office of Intelligence (AFOIN) or to all the information
Project Blue Book.
Much of this information has
been disclosed in the years since 1968. The information release
has come about on five fronts. First, the U.S. Air Force
released the complete files of Project Blue Book in 1975.
This release included the previously
unavailable files of the Air Force Office of Special
Second, the U.S. Freedom of Information
Act, which went into effect in the mid 1970s, resulted in the
release of relevant information from other agencies,
Federal Bureau of
Investigation - FBI, in 1977
Agency - CIA, in 1978
...though often in a censored form.
A third new source of information is the collection of
previously withheld reports and analyses carried out by the
AFOIN in the late 1940s and early 1950s. This information has
been released in the last 20 years as a result of standard
declassification requirements for old documents.
It shows that Air Force intelligence
privately concluded that as many as 5% of the sightings were
unexplainable even though they were apparently accurate reports
made by credible observers, thus contradicting the public
statements of the Air Force that all sightings could be
The documents provide an explanation
as to why Air Force intelligence told the FBI in August and
again in October, 1952, that some top Air Force officials were
seriously considering the 'interplanetary' explanation.
Fourth, governments of countries other than the United States,
over the last 25 years, have released relevant information
collected by their armed services and police.
Not only has the
French government, through
SEPRA, released sighting
documents but also England's Ministry of Defense recently
released a number of documents.
The governments of Spain and Canada
also released documents in the 1970s and 1980s. Moreover, some
governments besides that of France have official investigative
groups on this topic.
In 1997, in response to civilian and
military sightings over the previous years, the Chilean Air
Force formed the Committee for the Study of Anomalous Phenomena
(acronym, CEFAA in Spanish) directed by a former Air Force
general and headquartered in the Technical School of Aeronautics
One of us (Maccabee) was invited to
Chile in 1999 to lecture at a symposium sponsored by the CEFAA
and to discuss the sightings.
The Peruvian Air Force set up a
similar group in 2001. Brazil and Uruguay also have comparable
A fifth new source of information not available or utilized by
the Condon group consists of the many witnesses to events in the
1940-1960 decades who had worked for the government or the
military and after reaching retirement age, have come forward to
divulge their first-hand knowledge .
They have felt it was
more important for the citizens to know what has been taking
place than to continue to obey instructions to maintain silence
A reluctance to report UFO events
arose because of a curtain of ridicule which, since the 1950s,
had settled over the subject. It was induced in part by the
CIA's 1953 Robertson panel that recommended a debunking
program against the reality of the phenomenon. [20,
The debunking is most often implemented by an authority figure
asserting, at his own volition and without interviewing the
witnesses, that whatever was observed and reported as
extraordinary was instead the misidentification of something
mundane. This is demeaning to sincere, credible witnesses.
The major news media quickly picked
up on sarcastic phrases like 'little green men' and 'UFO buffs',
then gradually weaned themselves away from the topic - reporters,
editors and corporate owners fear ridicule, whether just or
unjust, as much as do scientists and politicians.
The refusal of
the U.S. Air Force in the 1950s and 1960s to release sighting
data it had collected only added to the problem, since evidence
collected by the government was not available to support the
The first director of the CIA assessed the situation in 1960 as
'Behind the scenes, high-ranking Air Force officers are
soberly concerned about UFOs.
But, through official secrecy and
ridicule, many citizens are led to believe the unknown flying
objects are nonsense… to hide the facts, the Air Force has
silenced its personnel'. 
The Condon Report also added to the
problem, since it demonstrated that men of science could simply
allege that witnesses are mistaken or dishonest and they would
be believed by most of their colleagues even though they had no
evidence to back up their allegations.
This in turn led to
greater reluctance on the part of witnesses to come forward. As
'the most credible UFO witnesses are often those most
reluctant to come forward with a report of the event they have
This ridicule factor has pre-vented
many serious investigators from even attempting to report their
findings within the journals preferred by most scientists.
Therefore, one of the recommendations made by the moderator of a
1997 panel of scientists is that journal editors should change
their policy of refusing to even seriously consider publishing
articles related to the UFO phenomenon, so that this difficulty
may be alleviated. 
6. Inferring an ET
If one allows that at least some unexplainable sightings may be
manifestations of extraterrestrial intelligence, then there is yet
another reason for reevaluation:
a growing recognition over the past
two decades that a large part of the behavior manifested can be
viewed as being quite rational.
The topic of ET behavior has
received considerable discussion in connection with SETI in the past
SETI has proceeded on the assumption
that Fermi's paradox is to be solved through continued and enhanced
searching of the sky for electro-magnetic signals indicative of ET
Several possible reasons for lack of success to
date have been proposed. [1, 37-38]
Since the 1970s advocates of a covert ET presence in our vicinity
have also been advancing their hypotheses or scenarios. They reject
as improbable the assumption that space-faring ETs must be dominated
by the most evil and aggressive of their kind - an assumption whose
consequence would be that we should not be existing as a freely
developing civilization within a fully colonized and/or explored
Contact optimists instead presume that
many advanced ET groups are at least as ethical as we are, while
still attending to their own safety and security. The ET motivation
for space travel could be to increase their knowledge through
exploration of space rather than to colonize and seek domination.
Thus hypotheses have been set forth regarding why such ETs
would be aware of our presence but not yet have contacted us
overtly. Among these are the zoo, nursery and quarantine or embargo
hypotheses. [1, 38, 40-42]
Most of these posit that the ETs
involved have frequently scouted us out semi-covertly and have
concluded that we are either not yet mature enough for open contact,
or not prepared for it, since any abrupt, overt contact could cause
societal chaos and governmental downfalls.
Also postulated is that
ET interference with our society would prematurely bring an end to
our civilization's continued development if it occurred before our
knowledge has progressed to the point that we could understand where
the aliens could have originated and how great their head start over
us could be. 
A serious inconsistency in this reasoning, how-ever, is that
maintenance of total ET covertness to-wards Earth and the solar
system would still lead to societal chaos whenever the covertness or
embargo was eventually lifted, unless the ETs carried out a
program of gradual disclosure - a 'leaky' embargo. [1, 43]
Although the zoo or embargo hypothesis
may be unverifiable, the leaky-embargo hypothesis may be verifiable
if the UFO evidence is taken into ac-count.
Much of this evidence
appears to constitute just such a leak in the embargo: a grass-roots
educational program in the form of the phenomenon, which has been
in operation since 1947, if not be-fore.
Many sightings have been of a nature to attract attention to their
craft and let isolated groups of witnesses know that its occupants
are aware of us. [24, 44]
A key category of such cases involves
re-ports wherein persons within a traveling vehicle frantically
witness an object pacing them even though their automobile or
aircraft makes turns that rule out the sighting of an astronomical
or other ordinary object as any explanation.
Similarly, in a number of the aircraft
cases the unknown object, which was either pacing the aircraft or
presenting itself to it, was detected on radar as well as visually.
The object's extraordinary appearance, maneuverability
and oft-times coincidental interference with the vehicle's
electrical system additionally rule out mundane explanations.
Although individual, localized and usually brief sightings may have
provided sufficient evidence to be convincing to the observers and
sighting analysts, the fact is that, since the widely-reported
sightings began in 1947, no event has persisted in a prominent place
a sufficient number of hours at a time, or demonstrated its
abilities to enough wit-nesses at a time, for the news media to
congregate and publicize it to the world.
Nor have they left quite
enough evidence behind to be totally convincing to very many
We suspect that this chary behavior may be no
To put it another way, from the viewpoint of investigators studying
such phenomena, individual close-encounter and other sightings can
be very intrusive and overt. However, from the viewpoint of the
scientific community and society as a whole, this is not the case,
because of the relative rarity in time and space of convincing
sightings and be-cause of the limited numbers of witnesses in most
The inference is that, by not providing
sufficient evidence to make their reality totally obvious to
scientists and society in general, the ETs are following a strategy
or program that avoids inflicting catastrophic shock to society as
a whole, which any overt contact could cause, while pre-paring us
for eventual open contact.
This could say something about their
level of ethics.
Proposing a certain level of ET ethics is not new; it was suggested
in 1981 that advanced ETs may abide by a Codex Galactica that would
require them to treat emerging civilizations delicately. [1,
a standard of behavior is consistent with reality of the UFO
phenomenon and the fact that not in the past 56 years, nor in past
millennia, have we been colonized, conquered or exterminated, nor
has society been traumatized by any ETs or by their sometimes
postulated robotic probes. [1, 41]
It is also consistent with the failure
of investigative panels to find that UFOs constitute any direct
threat to national security. On the other hand, it appears all too
evident that ETs have not intervened in world affairs in any
benevolent manner that would have forestalled human war-fare, famine
In fact, ample cases exist wherein the witnesses, when
too close, were injured or harmed. Other cases exist, however, in which a
witness was healed of some injury or medical condition. 
this suggests that ET interactions with humans are based on a
neutrally benevolent ethical level overall.
Despite the UFO phenomenon having continued now for over two
generations, the huge technological head start of the presumed ETs
would still come as a great shock to many scientists as well as
the Brookings Report indicated.
It could be so great as to seriously
challenge our consensual reality, a not insignificant danger.
implication that we would be powerless relative to their presumed
capabilities and evolutionary advantage may be most un-welcome, with
it being no surprise that science would have difficulty coming to
terms with the situation. 
Nevertheless, the reality of the
phenomenon and of our having long since been discovered by advanced
ETs now may be more probable than that Fermi's paradox is to be
resolved through either the non-existence of advanced ETs or their
inability to explore or colonies the galaxy.
Hence open scientific
research on the subject is needed with special attention paid to
high quality UFO reports exhibiting apparent indications that ET
intelligence and strategy are involved.
We thank P. Sturrock of Stanford
University and T. Roe of the National Aviation Reporting Center on
Anomalous Phenomena (NARCAP) for suggested improvements.
S. Webb, "If the Universe is Teeming with
Aliens…Where is Everybody? Fifty Solutions to the Fermi
Paradox and the Problem of Extraterrestrial Life",
Copernicus Books, New York, 2002.
E. Dudas, "Theory and phenomenology of type I
strings and M-theory", Class. Quant. Grav., 17, R41, 2000,
K.D. Olum, "Conflict between anthropic
reasoning and observation", ANALYSIS, 64, p.1, 2004, (gr-qc/0303070).
S. Udry, M. Mayor, and N.C. Santos,
"Statistical properties of exoplanets. I. The period
distribution: Constraints for the migration scenario",
Astron. Astrophys., 407, p.369, 2003.
B.C. Coughlin, "Searching for an alien haven
in the heavens", Proc. Natl. Acad. Sci. U.S.A., 98, p.796,
D.P.Glavin, O. Botta, G. Cooper, and J.L.
Bada, "Identification of amino acid signatures in
carbonaceous chondrites", Proc. Natl. Acad. Sci. U.S.A., 98,
M.K. Wallis and N.C. Wickramasinghe,
"Interstellar transfer of planetary microbiota", Mon. Not.
R. Astron. Soc., 348, p.52, 2004.
W.M. Napier, "A mechanism for interstellar
panspermia", Mon. Not. R. Astron. Soc., 348, p.46, 2004.
M.S. Morris, and K.S. Thorne, "Wormholes in
spacetime and their use for interstellar travel: A tool for
teaching general relativity", Am. J. Phys., 56, p.395, 1988.
M. Visser, "Lorentzian Wormholes: From
Einstein to Hawking", AIP Press, Woodbury, New York, 1996.
M. Alcubierre, "The warp drive: Hyper-fast
travel within general relativity", Class. Quant. Grav., 11,
H.E. Puthoff, "SETI, the velocity-of-light
limitation, and the Alcubierre warp drive: An integrating
overview", Phys. Essays, 9, p.156, 1996.
S.V. Krasnikov, "Hyperfast Interstellar
Travel in General Relativity", Phys. Rev. D, 57, p.4760,
R.H. Dicke, "Gravitation without a Principle
of Equivalence", Rev. Mod. Phys., 29, p.363, 1957.
H.E. Puthoff, "Polarizable-vacuum (PV)
approach to general relativity", Found. Phys., 32, p.927,
M.J. Pfenning, and L.H. Ford, "The unphysical
nature of warp drive", Class. Quant. Grav., 14, p.1743,
M. Visser, S. Kar, and N. Dadhich,
"Traversable wormholes with arbitrarily small energy
condition violations", Phys. Rev. Lett., 90, p.201102-1,
H.E. Puthoff, S.R. Little, and M. Ibison,
"Engineering the zero-point field and polarizable vacuum for
interstellar flight", JBIS, 55, p.137, 2002.
C.H. Lineweaver, Y. Fenner, and B.K. Gibson,
"The galactic habitable zone and the age distribution of
complex life in the Milky Way", Science, 303, p.59. 2004.
D.M. Jacobs, "The UFO Controversy in
America", Indiana University Press, Bloomington, Indiana,
Project Blue Book Special Report No. 14,
E.U. Condon, and D.S. Gillmor, "Final Report
of the Scientific Study of Unidentified Flying Objects",
Bantam Books, New York, 1969.
R.M. Dolan, "UFOs and the National Security
State", Hampton Roads Publishing Co., Charlottesville,
R.H. Hall, "The UFO Evidence", vol. II,
Scarecrow Press, Lanham, Maryland, 2001.
P.A.Sturrock, "The UFO Enigma: A New Review
of the Physical Evidence", Warner Books, New York, 1999.
P.A. Sturrock, "An analysis of the Condon
Report on the Colorado UFO project", J. Sci. Exploration, 1,
J.E. McDonald, "Science in Default", in
"UFO's-A Scientific Debate", Eds. C. Sagan and T. Page,
Cornell University Press, Ithaca, NY, 1972, p.52, 1972.
S.J. Dick, "The Biological Universe: The
Twentieth-Century Extraterrestrial Life Debate and the
Limits of Science", Cambridge University Press, England,
D.R. Saunders and R.R. Harkins, "UFOs? Yes!
Where the Condon Committee Went Wrong: The inside story by
an ex-member of the official study group", World Publishing,
New York, 1969.
J.E. McDonald, Review of "The Condon Report,
Scientific Study of Unidentified Flying Objects", Icarus,
11, p.443, 1969.
B. Maccabee, "Photometric properties of an
unidentified bright object seen off the coast of New
Zealand", Appl. Opt., 19, p.1745, 1980.
B. Maccabee, "Analysis and discussion of the
images of a cluster of periodically flashing lights filmed
off the coast of New Zealand", J. Sci. Exploration, 1,
B. Maccabee, "UFO-FBI Connection: The Secret
History of the Government's Cover-Up", Llewellyn
Publications, St. Paul, Minnesota, 2000.
J. Deardorff, B. Haisch, B. Maccabee and H.E. Puthoff
R. Hillenkoetter, New York Times, February
P.A. Sturrock, et al. "Physical evidence
related to UFO reports: The proceedings of a workshop held
at the Pocantico Conference Center, Tarrytown, New York,
September 29-October 4, 1997", J. Sci. Exploration, 12,
J. Tarter, Book review (astronomy): "Ongoing
debate over cosmic neighbors", Science, 299, p.46, 2003.
B. Gato-Rivera, "Brane worlds, the
subanthropic principle, and the undetectability conjecture",
T.B.H. Kuiper, and M. Morris, "Searching for
extraterrestrial civilizations", Science, 196, p.616, 1977.
J.A. Ball, "The zoo hypothesis", Icarus, 19,
G.D. Brin, "The 'Great silence': The
controversy concerning extraterrestrial intelligent life",
Q. J. R. Astron. Soc., 24, p.283, 1983.
E.R. Harrison, "Cosmology", Cambridge
University Press, Cambridge, 1981.
J.W. Deardorff, "Possible extraterrestrial
strategy for Earth", Q. J. R. Astron. Soc., 27, p.94, 1986.
R. Haines, "CE-5 Close Encounters of the
Fifth Kind", Sourcebooks, Naperville, Illinois, 1998.
W.I. Newman and C. Sagan, "Galactic
civilizations: Population dynamics and interstellar
diffusion", Icarus, 46, p.293, 1981.
P.E. Dennett, and C. Dennett, "UFO Healings",
Granite Publishing Group, Columbus, North Carolina, 1996.
U.S. House of Representatives Report No. 242,
"Proposed Studies on the Implications of Peaceful Space
Activities for Human Affairs", 1961.
P.A. Sturrock, "Extraterrestrial intelligent
life", Q. J. R. Astron. Soc., 19, p.521, 1989.