W
ow!, writes Jerry R. Ehman
in red on the printed
read-out in front of him.
It is August 1977, and the
astronomer is reading
data from the Big Ear radio telescope, when
unusual code among the endless rows of 1s,
2s, and 3s makes him stare. The ‘6EQUJ5’
sequence indicates radio waves 30 times
more powerful than the usual background
radiation of space. Ehman immediately
draws a circle around the sequence, before
writing the letters that subsequently become
the signal’s name.
During the month following the ‘Wow!’
signal, astronomers aimed the Big Ear at the
Sagittarius constellation, where the waves
came from. But the 72-second radio signal
was never repeated. Since then, astrono-
mers have built better and more powerful
telescopes, and have scanned a larger
section of the sky, but to no avail. Ehman’s
signal is still the only known potential
attempt by aliens to contact us.
Now a new organisation, METI, is tired of
waiting. So it aims to actively contact any
aliens’ home planets, hoping to establish a
permanent hotline. This requires a clear
message, improved signal transmission meth-
ods, and exoplanets with a likelihood of life.
Who might be out there – and are they friendly?Other planets ought to include life
The search for intelligent life in space took
off seriously with Project Ozma in 1960,
when astronomer Frank Drake scrutinisedradio signals from two Sun-like stars. The
search is known as SETI – Search for Extra-
terrestrial Intelligence – and since 1984,
international cooperation in the search has
been anchored within the framework of the
Californian SETI Institute.
This organisation, as well as several
researchers such as the 2019 Nobel Prize
laureate in physics, Didier Queloz, are posi-tive that we cannot be the only sentient life
in the universe. In the Milky Way alone,
according to calculations, some 10 billion
planets are likely to be located in the inhab-
itable zone where heat from a star is neither
too intense nor too insignificant. Although
studies recently shrank the zone, there are
still billions of planets out there with the
same basis for life as Earth.
If life probably exists on other planets,
why have we not been paid a visit? This
question constitutes the Fermi paradox,named after Italian physicist Enrico Fermi.
One possible answer is that we are effec-
tively alone in the universe because other
life forms are either unsophisticated or have
become extinct. Another explanation is the
zoo hypothesis: that aliens passively
observe other planets, as do we, so far.
METI International is a breakaway group
from the SETI Institute that aims to test
the zoo hypothesis by actively telling aliens
about our existence. ‘METI’ is an acronym
for Messaging ExtraTerrestrial Intelligence,
and in 2017 the independent research
organisation sent its first signal towards an
exoplanet that might be inhabited.Symbolic signals miss the target
This isn’t the first ever attempt. Over the
past 50 years, more than 30 messages have
been sent into space. In 2012, the 305m-wide
Arecibo radio telescope in Puerto Rico sent a
reply to the ‘Wow!’ signal. It contained
10,000+ tweets and videos from people both
ordinary and famous. But the aim of the
message was primarily to prompt interest in
extra-terrestrial life in order to advertise a
UFO programme on the National Geographic
TV channel. Other messages have been
primarily symbolic, such as when NASA in
2008 sent The Beatles’ song Across the Uni-
verse on a journey towards the North Star.
Even the Arecibo Message, sent from the
telescope bearing the same name in 1974,
was primarily meant to demonstrate the
telescope’s capability, and besides, the signal
will miss its destination, the M13 globular32
radio signals are travelling
from the Earth towards
exoplanets and stars.Astronomers write messages to aliens according
to Zipf’s law, a linguistic pattern which is obeyed
even by humpback whales. According to this law,
the most widely used word occurs twice as often
as the second most frequently used.
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