Did FAST telescope find alien radio signals?
Hidden in the middle of the Chinese mountains,
there's one of the biggest astronomical observatories that we ever built.
It is called FAST, and it is a radio telescope large 500 meters.
Generally speaking, the resolution of a telescope goes with the inverse of its diameter. The bigger
it is, the better the resolution. And, since in the radio regime the resolution is worse,
radio telescopes have to be huge in order to resolve far away objects.
This telescope is able to study the radiation coming from the most distant galaxies,
the primordial ones. Some of them lie something like 13 billion light years far away from us!
The telescope can provide information about
the supermassive black holes that these galaxies host in the center.
These should be the first supermassive black holes born in the universe!
But perhaps the most interesting thing about this telescope is that being a radio telescope,
it can detect radio signals from potential alien civilizations.
Maybe, somewhere out there, there is some alien civilization trying to get in touch with us by
means of radio signals, who knows? So, in a nutshell,
this telescope could be one of the first steps toward interplanetary communication.
Now everything is set and astronomers are only waiting for the first data release.
They will analyze and process it, and the results will be available for everyone.
But some info leaked out: they seem to have found something really strange, and maybe
there is a chance that they actually detected a signal from an extraterrestrial civilization.
Global Times – which Twitter describes as
“China state-affiliated media” – was one source that published the story, which was based on this
(now-deleted) report. It said China's FAST radio telescope has found several
possible technical traces and suspected signals of extraterrestrial civilizations.
But how do recognize an alien message? And why did they delete the tweet?
Every time we deal with the search for extraterrestrial intelligence (SETI),
one of the biggest problems is NOISE. In fact, the more our telescopes are
sensitive, the more the chances of finding some interesting. But we also detect a lot of noise,
which is basically a lot of useless data, that scientists always strive to get rid of.
Take a look at this image. It shows a typical example of a signal, along with its associated
noise. In fact, every instrument has its own background noise, something associated with the
instrument itself. The so-called “Signal to noise ratio” is an important quantity to be defined.
The ratio is typically expressed as a single numeric value in decibels. The ratio can be zero,
a positive number, or a negative number. A signal-to-noise ratio over 0 dB indicates that the
signal level is greater than the noise level. The higher the ratio, the better the signal quality.
For example, a Wi-Fi signal with S/N of 40 dB will deliver better network services than a signal with
S/N of 20 dB. If a Wi-Fi signal's S/N is too low, network performance can be impacted because it
becomes more difficult for devices to distinguish the desired signal from the noise. This can result
in dropped packets and data retransmissions, leading to lower throughput and higher latency.
On the other hand, noise could be everything that is considered not important for your research.
For instance, if your research is about supernovae, it might happen that,
surveying the sky, you might find some asteroids crossing your telescope. Therefore, you will
have some signals that are NOISY to you, in the sense that they are considered unimportant, even
though they might be useful to other astronomers working in the field of asteroids. It only matters
what you are looking for. Shortly speaking, you decide what's noise and what is not.
When we were at the beginning of our research with telescopes, everything was a bit easier in
a sense, because the first telescopes weren't that powerful, and they could only detect very strong
signals, and we were basically only interested in bright sources, that were quite distinguishable
from the background noise signal, for example, of the telescope itself, or the sky signal.
But now we are making a different science, and we are looking for an ever-increasing number of
low emission sources. Therefore, we really want to get rid of the noise, as much as possible.
Guys, trust me: it is an enormous problem!
The radio telescopes we have today are so powerful that they would be able to detect
radio signals from planets far away from us, up to something like 10 light years from us.
If there was a control tower on a planet 10 light years from us,
and if this control tower was sending out radio signals,
we would be able to detect them. This is how powerful telescopes like FAST are.
The problem is that...this signal would be so weak that we wouldn't
be able to distinguish it from the noise of our sample. In this case,
one thing that might help in the future could be artificial intelligence.
AI could help us distinguish between the signal that we are looking for
and the noise. We sure would not be able to do the job!
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But don't despair! The more a telescope is being used,
the more astronomers are aware of its limitations, and its contribution to the noise. This is good
news, because FAST is a new brand telescope, and it is...NEW indeed! We are pretty confident
astronomers will have time to better understand how to get more reliable and decipherable data.
Also, the Chinese scientific community never had such instrumentation before,
and therefore they are “new” to this kind of job. Maybe it will take some time for
them to get rid of the noise, but in the end, they could find reliable signals.
This of course doesn't mean that the upcoming data release doesn't contain alien signals at all,
but probably it is too soon to tweet we find one. So what happened with the tweet?
Well, as Zhang Tongjie, chief scientist of China ET Civilization Research Group said,
“The possibility that the suspicious signal is some kind of radio interference is also very high,
and it needs to be further confirmed or ruled out. This may be a long process.”
Zhang is also reported to have said that the team spotted two
sets of intriguing signals in 2020 while sifting through FAST data gathered in 2019.
Another signal was apparently picked up this year in data gathered on exoplanet targets.
However, Zhang reportedly also underscored the possibility that the signals are products of
radio interference. What does this mean? It means that every day on Earth, there
is an indefinitely large amount of emissions that could make their way into the telescope.
Maybe the telescopes detected one of such signals, by mistake. Basically,
radio pollution rather than alien civilization could be the reason for this detected signal.
The technical term we use is 'RFI' — radio frequency interference.
RFI can come from cell phones, TV transmitters, radar, satellites,
as well as electronics and computers near the observatory that produce weak radio transmissions.
This is important to remark. For instance, the SETI project, dedicated to the search
for extraterrestrial life, had already found something like this in the past.
Basically, all of the signals detected by SETI researchers so far are actually made by our own
civilization. We are the alien civilization! And the thing is, with radio pollution increasing over
time, it is getting really hard to do SETI observations from the surface of the Earth.
Someone suggested that we might as well consider going on the far side of the moon to do SETI work.
So if you are interested in engineering, why don't you come up with a clever and
cheap idea to build a nice radio telescope on the moon? There,
your beautiful telescope will be shielded from all of our planet's radio pollution.
This is not the first time we mistake an alien signal for a terrestrial one.
For example, in April 2019, the Breakthrough Listen Initiative (BLI) performed observations
of our nearest stellar neighbor, Proxima Centauri (ProxCen), with
the Parkes Murriyang telescope in Australia. We were originally searching for stellar flares;
learning more about these flares can help us understand the habitability of planets around
small, M-dwarf stars like ProxCen. Two years later, the same data were reanalyzed in the
context of SETI, looking for technological radio activity from ProxCen. Shane Smith,
a student working with Breakthrough Listen over the summer of 2020,
was the first one to notice that the routine analysis had picked up something unusual. For
once, no one in the group had an immediate answer to what could've caused the signal in that plot.
Here's the plot:
As you can see, there's a line that crosses the plot from left to right.
That was a strange signal: first of all, it was a narrowband signal. Signals this
narrow have no known astrophysical source and are typical of artificial transmitters.
But perhaps the most interesting thing was that the signal appeared to be absent in the
off-source observations, as would be expected for a signal coming from a single point in the sky.
It was almost as if some aliens had built an artificial transmitter
and were pointing it towards us, sending signals in a specific band.
What the researcher did was very careful research to find a match between all the possible radio
signals generated here on Earth, and what they found was that blc1, as the signal was called,
was an intermodulation product of some Earth-based transmitter. Intermodulation
production is a characteristic of a particular kind of transmitter inefficiency or malfunction.
So it wasn't aliens. It was our malfunctioning transmitters.
As you can understand, science is always exciting, but it is made up of little steps
that, sometimes, might seem boring! Imagine astronomers working at the
FAST radio telescope. This telescope detects something like 38 billion signals per second!
Imagine the huge quantity of data FAST collected during the course of one year: all of it, is going
to be analyzed and processed by supercomputers and, I would say, super astronomers!
We just have to wait until we'll have more reliable data,
and who knows: maybe we will finally find some evidence for extraterrestrial civilization!
Wouldn't be exciting if we did?
This video ends here! What do you think about it? Let me know in the comments below and be sure to
watch our other video about alien life through the youtube endscreens, playlists and cards!