00:00In the 1970s, we received a radio signal that lasted more than a minute, and to this day, no one knows what it was or where it came from.
00:10But today, a new theory has appeared. Could the mystery finally be solved?
00:16In 1977, at 11.16 p.m., an Ohio telescope captured something very unusual in space.
00:25It was a very short radio signal, only 72 seconds long.
00:30The signal was so loud and so strange that the scientist present at the time of its reception wrote,
00:35« Wow! » to the red ink next to the measurement scale.
00:38This is why it is called the « Wow! » signal.
00:41In space, gaseous hydrogen sometimes emits radio waves, a type of electromagnetic radiation.
00:47These waves have a specific frequency, which in a way constitutes the unique signature of hydrogen gas,
00:54and which allows us to identify and study it.
00:56Knowing this, it was possible for us to determine that the frequency of the « Wow! » signal came from the same place as this gas.
01:03But that doesn't help us much, we still have no idea what it emitted.
01:07What is even stranger is that the signal only appeared once.
01:12Even if we tried very hard to catch it a second time, we never got there.
01:17And in the absence of repetition, it was impossible for us to know what it was.
01:22It was even difficult for us to determine its precise position due to its great briefness.
01:28From a certain distance, it is particularly difficult to determine the origin of radio signals.
01:34As a result, this led to several theories.
01:41The frequency of the « Wow! » signal was particular, it was not overloaded by other signals.
01:46It's like when you find a quiet place in a noisy room.
01:49When there is not a lot of interference on a given frequency,
01:52the sent signal can travel very far without being lost or distorted.
01:56And this is very interesting, because it means that this would be the ideal frequency to send messages
02:02if we wanted to communicate with extraterrestrial creatures.
02:05Could it be that we are trying to contact us?
02:08This is a real scientific possibility.
02:10Nobody knows what was the origin of the signal we are talking about.
02:14But if it came from extraterrestrials, what is certain is that they do not communicate like us.
02:20The signal did not look like a deliberate message.
02:24And it is strange that it happened only once.
02:27If it was a small green people trying to contact us, it would be strange that it only happened once.
02:33But just in case, in 2012, on the occasion of the 35th anniversary of the « Wow! » signal,
02:38we decided to send a series of messages to certain stars.
02:42We used a special code so that the extraterrestrial creatures that would receive them would know that they had just been intelligent.
02:49Finally, relatively intelligent.
02:51And we used a lot of energy to make sure that the messages traveled very far.
02:59Scientists have issued many theories about the possible origin of the « Wow! » signal.
03:04But none of them is the subject of a consensus.
03:08What is certain is that it does not come from a terrestrial source.
03:12Terrestrial noises can sometimes interfere.
03:15But this signal undoubtedly came from space.
03:18There was a theory that a terrestrial signal would have bounced on space debris before coming back to us.
03:25But we quickly understood that such a thing was very unlikely.
03:29Another idea is that the signal would have been caused by a sentiment similar to that of the stars.
03:34But even if it was true, it did not exclude the possibility that the signal was produced by something artificial.
03:40According to another hypothesis, the signal could come from a rotating object, like a lighthouse.
03:45It is also possible that the signal has changed frequency over time, or simply that it has only been emitted once.
03:54It has now been almost 50 years since this strange signal was captured.
03:58But recently, a new idea about its origin has emerged.
04:01Imagine a comet passing through space and leaving a trail of gas behind it.
04:06This gas could be the key to this mysterious radio signal that attracted the attention of astronomers around the world.
04:12An astronomer who examined the « Wow! » signal thought it could be linked to a comet called 276P Christensen.
04:20Yes, not bad as a name.
04:22This comet is about 1,800 light-years away from us.
04:25It was not known in 1977 when the signal was detected.
04:29But it could now provide us with an explanation.
04:32Comets can emit radio waves when they approach the sun.
04:36It is as if the gases surrounding them were beginning to overflow with energy.
04:40This overflow could be the origin of the « Wow! » signal.
04:43To verify this theory, we used a radio telescope to listen to the radio waves emitted by other comets.
04:50And we found that some comets were actually emitting radio waves at the same frequency as the « Wow! » signal.
04:56Then, we pointed our telescopes at a particular comet passing through the same part of the sky as the one where the « Wow! » signal was detected.
05:04The radio waves of the comet corresponded to our signals.
05:07And even if the comet was not exactly at the same place as the signal,
05:11it was close enough for us to feel like we were on a track.
05:16The signal could also have been caused by hydrogen clouds from two comets.
05:21The one we mentioned, and another, called P2008 IR2.
05:27But who chooses these names?
05:32But not everyone is convinced by this idea.
05:35Some say that the theory of the two comets at the origin of the signal does not hold up.
05:40Because comets generally do not emit radio waves in the required way to explain the « Wow! » signal.
05:47In addition, the signal did not repeat itself.
05:49It only occurred once, which would be strange if it were really a comet.
05:54Indeed, comets spread their gases over a long distance.
05:58The signal would therefore have to last longer.
06:00The telescope used to detect it should have caught it twice in a short time.
06:04But that's not what happened.
06:06In addition, the comet would not have left the telescope's field of vision so quickly.
06:11In short, we have to learn more about the way comets emit radio waves,
06:16and the reasons why they do so,
06:19especially when it's on the same frequency as the « Wow! » signal.
06:26There are many mysterious and interesting signals in space.
06:30Most of them come from natural events, such as fast-radio surges.
06:35These energy bubbles are incredibly powerful and occur everywhere in the sky.
06:40But their origin is not yet very clear.
06:43They only last a fraction of a second.
06:45But maybe our telescopes only capture a small part of it.
06:49There is also this strange signal that we have been receiving for a while now.
06:53This signal is repeated every 22 minutes.
06:56But despite our efforts, we are unable to determine its origin.
07:00It started in 1988, and we have been investigating this mystery for 36 years.
07:06At least, today we know the distance from the mysterious object that sends the signals.
07:11It is 15,000 light-years away.
07:18Some people think that these signals could come from extraterrestrial beings
07:22who try to communicate with us.
07:24However, in the absence of solid evidence, we cannot affirm it with certainty.
07:28It remains in the hands of speculation.
07:31Another explanation is the theory of pulsars.
07:34Pulsars are neutron stars that emit energy beams similar to those we observe with signals.
07:41However, the behavior of signals does not correspond perfectly to what we know of pulsars.
07:47There is also the theory of magnetars, which suggests that these signals could come from neutron stars.
07:54However, none of these theories fully explain the strange behavior of signals.
08:00Maybe this is the fact of a new phenomenon not yet discovered in the universe?
08:08Even if comets are a possibility, we still have a lot of questions about the Wow signal.
08:13We do not know what caused it, and we may never know.
08:17We do not even know if it comes from outer space or from within the solar system.
08:22Anyway, even if this signal has a natural cause, it does not mean that extraterrestrial life does not exist.
08:29The study that raised this subject also dealt with a star similar to the sun,
08:33which could well be the ideal place to look for signs of extraterrestrial technology.
08:38There are many other stars similar to our sun in space, but we have not studied them well yet.
08:45However, this opens up exciting perspectives for the research of advanced civilizations beyond Earth.
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