[This is a transcript of the video embedded below.]

The interstellar object ‘Oumuamua traveled through our solar system in 2017. Shortly after it was discovered, astrophysicist Avi Loeb claimed it was an alien technology. Now it looks like it’s just a big piece of nitrogen.

This wasn’t the first time scientists accidentally yelled at aliens, and it certainly won’t be the last. So in this video we’re going to look at the history of supposed extraterrestrial discoveries. What did astronomers see, what did they think, what turned out to be in the end? And what should we do with these claims? That’s what we’ll talk about today.

Then let’s talk about all the times when aliens weren’t aliens. In 1877 the Italian astronomer Giovanni Shiaparelli examined the surface of our neighboring planet Mars. He saw a network of long, almost straight lines. At the time, astronomers did not have the opportunity to take photos of their observation, and the usual procedure was to make drawings and write down what they saw. Shiaparelli called the structures “canali” in Italian, a word that does not specify their origin. In the English translation, however, the “canali” became “canals”, strongly suggesting an artificial origin. The better word would have been “canals”.

This translation error made scientific history. Although the telescopes’ resolution at the time wasn’t good enough to identify surface structures on Mars, several other astronomers were quick to report that they were seeing canals as well. At the turn of the 19th and 20th centuries, the American astronomer Percival Lowell published three books in which he hypothesized that the canals were an irrigation system built by an intelligent civilization.

The idea that intelligent life once existed, or perhaps still existed, on Mars persisted until 1965. This year the American space mission Mariner 5 flew past Mars and sent the first photos of the surface of Mars back to Earth. The photos showed craters, but nothing resembling canals. The channels turned out to be imaging artifacts, aided by vivid imagination. And although the scientific community put the idea of ​​channels on Mars to rest in 1965, it took much longer for the public to get over the idea of ​​life on Mars. I remember my grandmother still telling me about the channels in the 1980s.

But in any case, ET’s friends didn’t have to wait long for new hope. In 1967, Irish astrophysicist Jocelyn Bell Burnell noticed that the Cambridge radio telescope she was working on recorded a repetitive signal that pulsed for a period of just over a second. She noted “LGM” on the printout of the measurement curve, short for “little green men”.

The little green men were a joke, of course. At the time, however, astrophysicists were unaware of any natural process that could explain Bell Burnell’s observations, and therefore could not completely rule out that it was a signal emanating from alien technology. However, a few years after the signal was first recorded, it became clear that it was not an alien, but a rotating neutron star.

Rotating neutron stars can build up strong magnetic fields and then emit a steady but directed beam of electromagnetic radiation. And since the neutron star rotates, we only see this beam when it is pointing in our direction. Because of this, the signal appears to be pulsed. Such objects are now called “pulsars”.

Life on Mars made a brief comeback in 1996. That year, a group of Americans found a meteorite in Antarctica that appeared to be carrying traces of bacteria. This stone was likely hurled towards our planet when a heavier meteorite hit the surface of Mars. In fact, other scientists confirmed that the Antarctic meteorite most likely came from Mars. However, they came to the conclusion that the structures in the rock are too small to be of bacterial origin.

That wasn’t it with alien sightings. In 2015, the Kepler telescope found a star with irregular changes in brightness. Officially, the star has the catchy name KIC8462852, but unofficially it is called WTF. That stands, as you surely know, where is the river? The name that remained at the end was “Tabby’s Star”, after the first name of its discoverer, Tabetha Boyajian.

At first, astrophysicists didn’t have a good explanation for the strange behavior of Tabby’s star. And so, it wasn’t long before a group of researchers from the University of Pennsylvania suggested that aliens build a megastructure around their star.

In fact, back in the 1960s, physicist Freeman Dyson had argued that advanced alien civilizations would try to get energy from their sun as directly as possible. To that end, Dyson speculated, they would build a sphere around the star. It has remained unclear how such a sphere would be constructed or remain stable, but well, they are advanced, these civilizations, so they probably figured it out. And they cover up their star to capture its energy, which can plausibly lead to a signal like the one observed by Tabby’s star.

Several radio telescopes scanned the area around Tabby’s star for signs of intelligent life, but found nothing. Further observations now seem to support the hypothesis that the star is surrounded by debris from a ruined moon or other large rocks.

Then, in 2017, Canadian astronomer Robert Weryk made a surprising discovery while analyzing data from the Pan-STARRS telescope in Hawaii. He saw an object passing close to our planet, but it didn’t look like a comet or an asteroid.

When Weryk retraced his path, it turned out that the object came from outside our solar system. The astronomers called it “Oumuamua”, Hawaiian for “messenger from afar, who arrives first”.

‘Oumuamua gave astronomers and physicists something to think about. It entered our solar system on a path that complied with the laws of gravity, with no evidence of further propulsion. But as it got closer to the sun, it started emitting particles that gave it an acceleration.

This particle emission did not match what is normally observed from comets. The shape of ‘Oumuamua is also rather untypical for asteroids or comets. The shape that best fits the data is that of a hard drive, about 6-8 times as wide as it is high.

When Oumuamua was first observed, no one had a good idea of ​​what it was, what it was made of, or what happened when it approached the sun. The astrophysicist Avi Loeb used the situation to claim that Oumuamua was the technology of an alien civilization. “[T] The simplest and most direct line from an object with all the observed properties from ‘Oumuamua to an explanation for them is that it was made.’

According to a new study, it now looks like Oumuamua is a piece of frozen nitrogen that was split off from a nitrogen planet in another solar system. It stayed frozen until it neared our sun when it began to partially evaporate. Although we will never know for sure because the object has finally left our solar system and the data we have now is all the data we will ever have.

And a couple of weeks ago we were talking about what happened to the idea that there is life on Venus. Check out my previous video to learn more about it.

What do we learn from it? When new discoveries are made, it takes time for scientists to collect and analyze all of the data, formulate hypotheses, and evaluate which hypothesis best explains the data. Before doing this one can only reliably say: “We do not know”.

But “we don’t know” is boring and doesn’t make the headlines. Because of this, some scientists take advantage of the situation to come up with highly speculative ideas before others can show they are wrong. Because of this, headlines about possible signs of extraterrestrial life are certainly entertaining, but they usually go away after a few years.

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