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men , are fascinated by the prospects
thaL man may evenLually find a uní–
verse virLually teeming wiLh in–
telligentl ife.
The unimagina ble distances in
the unive rse seem Lo preclude direct
tra ve l by future as Lronauts Lo ex–
plo re other wo rlds. Even if a space–
ship moved at the limiting spced of
li ght (1 86.000 miles per second ).
such space voyagcs would still take
cen turies o r millennia in earLh time.
The New Telescopes
However, developments in radio
te lescopes have now reachcd the
po int where ma n has the technical
know-how and facilities to broad–
cast his exis tence throughout the
M
ilky Way ga laxy. In other words,
if rna n's most powerful transmitLer
were channeled inLo ma n's la rgest
radio Lelescope, its radio message
could be monitored by present-day
eq uipment on Lhe o ther side of the
ga laxy - 100,000 light years or 600
qua drillion miles away!
The ca pability now exists for a
very sophisticated sea rch fo r in–
Lelligence on other worlds.
In 1960, astronomer Frank Drake
used the giant radio telescope a t the
U.S. National Radio Astronomy
Observa tory to monito r radio waves
from nearby sLa rs in the hope of
de tecting signa ls from o ther civ–
ili za t io ns. Drake's ex p e riment.
ca lled proj ect Ozma, failed to pick
up a ny strange (int elügent) signals,
but the sensitivity o f hi s equipment
was no t very high.
More recently, as tronomer G. L.
Verschuu r sca nned ten nearby sLa rs
for signs o f life. His a ppara tus was
so sensitive thaLit could find in fi ve
minutes wha t Drake 's equipment
would have needed twenty days to
de tect. Verschuur's a pparatus could
have picked up signals from Barn–
ard's star radia ted by a 600-kilowa tt
tra nsmiller ac ting into a modest
300-foo t-diamet er radio telescope.
(Continued on page 40)
"EYE ON THE SKY"
-
The Jodre/1
Bank radio te/escope (left, above) is
capable ot detecting intelligent sig–
nals trom remote corners ot the
universe. Below: The tamed 100-inch
telescope on Mount Wilson in Cali–
fornia.
/ts
big eye helped expand
man 's understanding ofthe awesome
size of the universe.
The
PLAIN TRUTH June 1976
The
Chanees
for
lntelligence
ls ma n pa rt of a cosmic commun ity
of intelligent be ings? How many
civiliza tions mi ght reasona bly be ex–
pec ted Lo coexis t in one ga laxy? Sci–
en tists usua lly break this diffi cul t
question into seven basic facto rs
that, muiLiplied togeLher, will yield
the expected number of such civ–
iliza tions. Th ese factors are:
• Th e ave rage rate of sta r fo rma–
tion in the galaxy.
known with a ny precision. and thcy
are often ass igned widcly differing
va lues. Fo r cxample. if a sui Lab le
planet exists, sorne scientists belicve
t he probabili ty is excellent that üfe
will eventually evolve. Others be–
li eve that even in a favora ble cnvi–
ronme nL the chances
against
life
evolv ing are astronomical. Similar
disagreemen ts exist fo r most o f the
rema ining factors.
Exo-biologist Ca rl Sagan beüeves
the number of technologica l civ–
ilizations is about
JO
percent of the
life time of such civiliza tions. T his
implies tha t the ave rage life time of
a highly technological civi lization
de termines the number of currently
existing civilizations.
Mankind a lready has an ominous
ability to self-destruct; yet it has
on ly been abou t lO yea rs since man
has been capable o f in terstella r
communica tion. lf we fail to survive
E
~
much longcr, and if we are repre-
~
sentative of other ga lactic civ–
t5
iliza tions, Lhen the li kely conclusion
:¡;
is tha t j ust one technological civ–
.i
il ization cu r rently ex is ts in the
<(
Milky Way ga laxy: ourselves. l f so,
THE BEAUTIFUL M81
spiral ga/axy
a massive scarch fo r ex traterrestrial
in Ursa Major. Do such distant
in telligence will proba bly be a was te
gataxies harbor intelligent civiliza-
o f time and funds.
tions?
O n the other hand, if some tech-
• The fraction of stars with plan–
e ts.
• The number of pla ne ts per
pl aneta ry system suita ble for life .
• The fraction of suitable planets
on which
lite
exists.
• The frac ti o n o f li fe- bea ring
plane ts wi Lh intelligence.
• The fraction of planets wi th in–
te lligence th a t devel ops a tech–
no logica l phase and interes t in
in te rstellar communicat ion.
• The average lifeLime of a tech–
no logical civilization.
None of the above factors are
no logical societies have lea rned to
survive indcfinitely, then the n um–
be r o f Lechnological civilizations
presently in our galaxy is much
grea ter. Sagan has calculated t hat if
only one percent of a ll civilizations
maste r the key to pe rpetuating
th emselves, then the cor responding
numbe r of civiliza tions in the galaxy
today becomes a bout one mi ll ion.
Ye t even if oLher intelligent civ–
ilizat ions do exist. the vast distances
be tween the sta rs
po~e
an awesome
and time-consuming cha llenge for
any two-way communica Lions be–
tween ga lactic commu nities.
39