SETI article - Is the Latest Crop Circle a Message from E.T?
Originally posted at www.seti.org/general/ao_message_crop.html and still available from the Internet Archive
Crop circles. Undoubtedly you're aware of these intricate patterns carved in the wheat fields of (mostly) England. But could they be signals from visiting aliens? Despite the fact that many of the circles are known to be the work of pranksters, interest in crop circles has enjoyed a recent revival thanks to a pair of new patterns that appear in a field next to the Chilbolton Observatory in Hampshire, England. One is of a face, and many say that it looks like the archetypal "gray" alien so often seen in films and television. The second is a modified version of the 1974 Arecibo message, broadcast in the direction of the globular cluster M13 in November of that year.
The Arecibo message, which was designed by Frank Drake (who was then Director of the Arecibo Observatory in Puerto Rico, and is now Chairman of the Board of the SETI Institute) together with his Observatory staff, was a simple graphic consisting of 73 rows of 23 "bits" per row. This number of rows and columns was chosen because each is a prime number. Prime numbers could be easily guessed by any recipients, and that would help them to decode the graphic. The message was sent by simple shifting of the signal between two frequencies in the 2,380 MHz band. It took three minutes to send the message.
The message itself gives the kind of information that any culture would want to learn about us: where we are located (at least within our solar system), what we look like (a crude stick figure), a simple drawing of the telescope used to send the message, and something about our biological construction (DNA and some of the building blocks of our biochemistry.) This message was sent as a "demonstration" to commemorate the upgrading of the 1,000 foot diameter Arecibo telescope with a new, more accurate reflector surface.
The crop circle found in Hampshire looks very much like the one broadcast in 1974. But there are some differences: the Hampshire pattern has replaced the Arecibo Telescope with another graphic that is reminiscent of a space satellite with solar cells. The diagram that depicts our solar system has been replaced with another that still has nine worlds, but planets 3 through 5 are offset, and the last is drawn larger than the others (or perhaps this is a depiction of the four Galilean moons of Jupiter). Finally, the graphic of the human has been modified by a stick figure that, while humanoid, has a far larger head.
Good fun, and a nice example of grain graffiti. But some folks think that this crop circle (and at least some of the more than a thousand other circles that have appeared in the last decade) are truly signals from visiting aliens. The aliens, in this view, have borrowed an idea from Carl Sagan's "Contact," and initiated communication by returning one of our own signals to us (albeit, somewhat modified.)
This is highly improbable. There is no evidence to suggest an other-than-earthly origin for these graphics. Some of the reasons why we are skeptical that this is a "signal" from afar are as follows:
The aliens, if
they've received this signal, would obviously be aware of our capability
to send and receive high-frequency radio. After all, they would only
know of the 1974 transmission by receiving it. And, of course, they've
made a point about radio by leaving their message next to a radio antenna.
So why would they resort to an extraordinarily crude method of "replying"
- carving simple messages in our wheat? Why don't they use radio? The
wheat graffiti only conveys a handful of information - roughly the equivalent
of a few sentences of any text. They could convey far more, in a matter
of seconds, by radio. If radio isn't their thing, why don't they simply
leave a copy of the Encyclopedia Galactica on the doorstep of
either the farmer or the radio observatory? They could arrange for a
radio blast sufficiently powerful to reach every FM or TV set in a hemisphere,
which would quickly convey far more information, and to everyone at
once. After all, if they're carving wheat, they're clearly visiting.
If they're not fond of radio, they could leave information on paper,
as a CD, or in whatever form is convenient. Any such scheme would
convey orders of magnitude more information than a wheat carving. Surely
aliens who can come to Hampshire are sophisticated enough to offer us
more information bits than one can find on a fortune in a Chinese cookie.
How come they look
like us? Hollywood aliens always look pretty humanoid, but this is an
anthropocentric conceit. Visit the local zoo, and you'll find critters
that share 3.5 billion years of evolution and a lot of your DNA. But
they don't look like you - they look like fish, or alligators, or…
A very important
point if you think this is a returned message: The 1974 signal was aimed
at the cluster M13, which has hundreds of thousands of stars. Of course,
M13 is 25,000 light-years distant, which means that the message will
not reach its target for another 250 centuries. Clearly, the crop circle
can't be a response from any of M13's inhabitants; they haven't gotten
the message yet. But what about a random, Milky Way star that might
be in the "beam" of the Arecibo message? Couldn't they have overheard
the transmission, and offered this clever carving in reply? No. The
Arecibo beam at 2,380 MHz is about 2 arcminutes, which is roughly 1/15th
the diameter of the full moon. That's an extremely narrow beam. Imagine
shooting an arrow through a giant space in which ping pong balls are
hung by threads. The ping pong balls are many miles apart. How long
would the arrow have to travel before it accidentally hit one of these
balls? This is analogous to the situation of the Arecibo message, moving
in its tightly focused beam through the spaces of the Milky Way. The
chances that it has hit another solar system in the 27 years since its
broadcast are… one in 50,000, approximately. If you make the reasonable
assumption that the aliens cannot travel faster than the speed of light,
then they must lie within 13-1/2 light-years to have received this message
and responded. The chances of a star system within the volume of space
filled by the beam out to this distance is closer to one in a half-million!
In other words, it's highly, highly unlikely that any
star system has yet been exposed to the Arecibo message. This is an
important point, as it is quantitative and not dependent on any other
assumptions about this crop circle: no other star systems could have
yet received this transmission. And incidentally, the odds that a nearby
probe could have intercepted it are even smaller!
information in the crop circle is the same as the Arecibo message, although
the DNA seems to have an extra strand and a somewhat different number
of nucleotides. It has also been noted that silicon is now indicated
as part of the biological construction kit, although this element, while
popular in science fiction, is rather poor at making the complex molecules
required for life. Still, it's remarkable how similar the aliens' biology
is to ours, even to the point of sporting a helical DNA molecule. They
also use the same number of sugars and bases that make up human DNA
to construct theirs. But it's remarkable (but undoubtedly a sign of
a boo-boo on the constructors' part) that the silicon mentioned above
doesn't figure into the formulae of any of these alien DNA components
(this point was made by Randy Wiggins.) In addition, keep in mind that
of the hundreds of possible amino acids, only 20 are used for earthly
life. In other words our biochemistry is somewhat specific. How curious
(and unlikely!) that theirs would match ours so closely!
Finally, the whole
matter of crop circles fails the baloney test, as Sagan would put it.
They can be easily made by people interested in creating a stir (you
can read a nice description of both crop circles and their construction,
as well as a claim by experts in the field, as it were, that they could
replicate the new grain graphics, at circlemakers.)
And of importance, there is a lack of convincing physical evidence that
anyone else has made them. You might also wonder why, despite its ample
supply of wheat fields, the U.S. is almost never the target of this
type of alien graphic: nearly two-thirds of all crop circles are in
England. We also note that Chilbolton was the location of other crop
circles in 1999 and 2000. Why would aliens resort to a signaling system
that conveys so little information and can only be used during the two-month
growth season, and then only at night? We are also informed by Chilbolton
that these recent glyphs appeared (as so many do) after a weekend.
Bottom line? The crop
circles are decorative, impressive, and provocative, but not informative.
We can expect better from true extraterrestrial intelligence.
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