The truth about the message that SETI detected from Proxima Centauri
Exciting end of the year!
Just in these days is leaking the news of the reception of a radio signal that seems
to come from the same direction in which Proxima Centauri is located.
A star too faint to be seen by the Earth with the naked eye, but which has a unique feature:
it is in fact the closest star to our solar system, just 4.2 light years away.
The signal has such characteristics as to prevent it from being dismissed a priori as
a terrestrial interference, raising the vague possibility that it is a transmission that
may come from some form of technologically advanced extraterrestrial intelligence.
It's too early to tell, but the world of science has been in a tizzy like it hasn't been in
a long time.
Picking up that strange radio emission were some of the astronomers involved in the Breakthrough
Listen Project, promoted in 2015 by Russian billionaire Yuri Milner to detect forms of
intelligence in the cosmos.
An ambitious program, with a budget of $ 100 million to be spent in ten years, a kind of
"SETI Renaissance" that sees in the front row the most prestigious names in research
and the main Observatories of the world.
A goal to be achieved by funding the purchase of "observation time" on radio telescopes
around the world and checking one by one at least one million stars in our nearby universe.
And it was thanks to this "Joint venture" between capital and advanced technology that
on April 29, 2019, the Parkes radio telescope, located in Australia's New South Wales, was
pointed at the star Proxima Centauri.
Not so much in search of aliens, but to study the giant flashes of light that Red Dwarf
stars like Proxima frequently emit.
The endowment of the large dish of 70 meters in diameter, however, is programmed to be
used "commensally" also for the research of the Project Breakthrough Listen, and then
the astronomers have observed the star for 26 hours as part of their study of stellar
flares, but have also archived the observational data for a subsequent examination aimed at
detecting any SETI signals.
An examination that was entrusted to Shane Smith, a young intern who began sifting through
the data in June 2020, and who in late October came across a signal at 982.002 megahertz
that appeared to originate from Proxima Centauri itself.
In the five years since the start of Project Breakthrough Listen is certainly not the first
time that something similar is found, but on all other occasions the emission was easily
attributed to some natural source or interference produced by human activity, and immediately
discarded To arouse the interest of any SETI researcher, in fact, a signal must first undergo
a long series of automated tests to rule out that it could be trivial terrestrial interference.
Hundreds of candidate signals are routinely discarded at this stage and only very few
are subjected to further investigation.
But not this time.
This time there was something more serious.
At that point, Shane Smith's team registered the signal with a more formal name: BLC-1,
which stands for "Breakthrough Listen Candidate 1" (and the fact that it was designated as
"candidate 1", i.e. the first serious candidate found in five years, shows how strict the
selection is) and went on to examine some very unusual features.
The first of which is that it arrived on a frequency of 982 MHz, a very narrow band,
usually never employed by human technology for satellite or other transmissions.
The second feature, really very suggestive, is that the signal has a slight Doppler effect,
compatible with transmission from a moving planet.
And as we know, Proxima Centauri has a planetary system consisting of a gas giant and a rocky
body, "Proxima b", a little bit bigger than the Earth...
But seriously Could the signal come from that planet?
Could it be?
Until we know more, we can't say more about it, partly because we don't know the orbital
inclination or rotational properties of Proxima b, so we don't know what acceleration signal
it would provide.
Without a good model for that planet and without knowing what the team saw, we can only speculate.
That said, if the signal repeats and turns out to be from Proxima, and if the signal
is not inherently modulated, then we could use the drifts to infer the accelerations
of the transmitter and possibly determine if it is on the surface of a planet and determine
the rotational and orbital period of that planet.
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In addition, and this is also a clue in favor, the radio telescope, which had recorded the
signal in scans lasting 30 minutes over a week, had correctly used the so-called "nodding"
technique, whereby the dish spends a period pointing to the target and an equivalent period
to look at another point in the sky, to verify that the signal really comes from the same
point.
If the signal is coming from something on Earth, you will receive it no matter what
direction the radio telescope is pointing.
If it comes from space, it will only appear when you point at the target.
In short, the ingredients to make those who yearn to declaim "we are not alone" dream
seem to be all there.
The problem is that the spectrum is full of these types of signals.
Occasionally someone even comes from an interplanetary probe, but most comes from satellites orbiting
the Earth and from terrestrial sources.
So there is also the other side of the coin, made of doubts and a lot of skepticism.
For example, it is considered an unfortunate symptom that BLC-1 is not a voice or information
modulated radio signal.
In the movie Contact, the signal coming from the star Vega contained engineering specifications
on how to build a spaceship...
Remember that?
The BLC-1 signal, on the other hand, doesn't even say "hello."
Perhaps the signal itself is the message?
Some kind of callback whistle to say "We are here"?
Some have then pointed out that the frequency is suspiciously close to an integer value
of megahertz, which would indicate for the signal a clear terrestrial origin.
It would be quite improbable, in fact, that the aliens used the same units of measurement
as us!
Another objection is that of those who emphasize the improbability that two inhabited planets,
Earth and Proxima b, could be at such an extraordinarily small distance from each other from a cosmic
point of view.
In addition, astronomers believe that most likely Proxima b, despite orbits in the so-called
"habitability zone", is not suitable for life because of the continuous flares of the parent
star, and the fact that showing the star always the same face, on one side is eternally night,
while on the other there is the eternal day.
Opinions completely shareable.
But what if we renounce to the idea that the planet must be inhabited, and we think instead
to have to do with a kind of lighthouse, or a repeater placed there by a civilization
that lives somewhere else?
If there is a galactic community, able to spread its technology everywhere, then it
could have created a communication network that disregards the habitability of the planets
where the repeaters are placed.
When we call a friend on his cell phone, the two phones do not send radio signals directly
to each other.
This would require too much energy and a too complex sorting system.
Instead, our phone sends the signal to the repeater closest to our friend's location.
By this logic, Proxima b might be the most likely place to act as the "last mile" for
any message to be delivered to our neck of the woods.
In fact, it may be the only planet enabled to transmit to us, despite not being inhabited!
In practice, if someone was trying to get our attention, wouldn't it be obvious that
he would start the signal from the place where we earthlings would look first, i.e. from
the nearest star?
And if we really want to use statistics to prove that it cannot be an alien signal, then
we could also ask ourselves: how many probabilities are there that a false signal of any nature
will turn on just in correspondence of the nearest star to Earth?
The answer would be: maybe one in half a million!
And only because it has been calculated that the signal could come from anywhere in a circle
of 16 arcminutes around Proxima (about half the angular size of the full Moon).
Otherwise, it would be many fewer!
Unfortunately, news of the signal leaked out before the team had finished its analysis,
so we are here commenting on the event based on second-hand data and information.
Someone in the "astronomical community" (we don't even know if he is a member of the team)
has in fact leaked the story to the British newspaper The Guardian.
However, the team is preparing in these days two scientific papers, which will probably
be published in January.
Before then no one will want to unbalance on the real importance of the signal, even
if in the scientific environment is evident a certain fibrillation.
In fact, an anonymous source confirmed, "It is the best candidate since the Wow signal,
the best-known precedent in all of SETI history".
The Wow Signal is the name given to a strong narrowband radio signal that was detected
by astronomer Jerry R. Ehman on August 15, 1977, while working on the SETI extraterrestrial
life search project with Ohio State University's Big Ear radio telescope.
The characteristics of the signal hinted at an origin outside the Earth and the Solar
System.
Lasting 72 seconds, that emission has never been fully explained, and it was never even
possible to identify the exact point from which it started.
Ehman, amazed by the characteristics of the signal, looked for the alphanumeric code in
red on the printouts printed by the radio telescope and noted next to the comment "Wow!",
expression with which the signal later became known.
Frank Drake, co-founder of SETI, to explain why the signal was never detected again, assumed
that it was sent by a distant civilization, which would focus all the energy emission
in a very narrow spatial beam and only for a few minutes, so that it could be received
at great distances.
A signal emitted in all directions, in fact, would have required the dispersion of a large
amount of energy.
In the case of the BLC-1 signal, on the other hand, the position is known very precisely,
and from the moment it was detected, the research team set out again to target Proxima Centauri,
but has yet to find anything.
"In order to make claims of scientific validity, you need to be able to re-examine and replicate
the phenomenon," Sheikh says "that's how the scientific method works."
That's why, despite the excitement, caution prevails in these hours.
Pete Worden, former director of NASA Ames Research Center and current executive director
of Breakthrough Initiatives invites to wait for the end of the verifications before drawing
conclusions: "Our team has picked up several unusual signals and is studying them carefully.
They appear to be interference that we can't explain at the moment; further analysis is
underway."
Seth Shostak, the senior astronomer at the SETI Institute in California, also takes his
foot off the gas.
The oscillation of the frequency of the signal excludes that it comes from a source located
on our planet, but this does not certify the alien origin.
It could have been emitted from an orbiting satellite, from one of the more than 2700
that buzz above our heads.
Even if not, however, the radio wave could come from space, but from a remote point simply
aligned to Proxima Centauri and perhaps hundreds of light years away.
Produced by a quasar, by a pulsar unless it is a natural radio emission from a world with
a strong magnetic field.
Shostak's list of explanations - think about it - even includes the microwave oven in the
dining room of the Parkes telescope...
But even the extremely cautious SETI astronomer concludes his reasoning this way: "Until we
know, we should continue to consider the alien hypothesis feasible.
After all, any SETI survey will be risky when we do it for the first time...
There will be a lot of calls for restraint intended to appease all-too-anxious minds.
But it's reasonable to expect that someday one of these suspicious signals will, in fact,
be the coveted evidence of a flowery intelligence on another world as well.
Caution is often a good idea, but one must be careful not to throw the baby out with
the bathwater.
After all, this baby could change our concept of the universe."