A researcher from the Laboratory of Statistical Biophysics at the École Polytechnique Fédérale in Lausanne (EPFL), Switzerland, has come up with a new explanation for why aliens "if they exist" do not communicate with us.
"We've only been looking for 60 years," says biophysicist Claudio Grimaldi. "The Earth could simply be in a bubble that happens to be free of radio waves emitted by extraterrestrial life."
In short, there is too much space to survey, and likely not enough space transmissions to cross our path. It builds on a statistical model previously used to study porous materials such as sponges - only instead of pores within the material, it was published to assess the distribution of extraterrestrial emitters that may or may not be somewhere in space. The message is to be patient. Searching for traces of communications in the universe requires time, effort, and money, and there is some debate about whether the search for extraterrestrial intelligence (SETI) is worth our time.
The research model begins with the assumption that there is at least one electromagnetic signal of technological origin in the Milky Way at any given time, and that the Earth has been in a quiet bubble (or spongy pore) for at least six decades, if not more.
And if so, then statistically there are less than 1 to 5 electromagnetic emissions per century anywhere in our galaxy.
In other words, they are as common as supernovae in the Milky Way - so not very common at all.
In such probability assessments, there are often assumptions on which to focus. Factors can be adjusted to be more optimistic (or pessimistic), adjusting for the probability of catching a signal in the future.
And according to the most optimistic scenario, with the conditions described, Grimaldi says it could take at least 60 years before we get a signal from aliens. In the least optimistic scenario, we are looking forward to waiting more than 2,000 years. Either way, we'll need a radio telescope pointed in exactly the right direction.
“Maybe we were unlucky enough to figure out how to use radio telescopes as we were traversing a part of space where electromagnetic signals from other civilizations were absent,” says Grimaldi. “To me, this hypothesis seems less extreme than the assumption that we are constantly bombarded with signals from all sides but we are, for some reason.” What, they are unable to detect it."
And as the tools we use to look into space continue to improve, we're discovering more and more planets that might have the right conditions for life to exist on them - and that means a greater chance that alien life is trying to get in touch.
However, we still have a lot of ground to cover in search, which is why modeling is so important to know where to search.
And if an alien civilization developed, for example, it might cluster around a group of planets and not be spread evenly as the analysis in this study assumed.
The best way forward, Grimaldi suggests, is with equivalent probes: so look for signals in data collected by telescopes focused on other missions, rather than using telescopes specifically to look for space communications.
"A better strategy might be to adopt the SETI community's previous approach of using data from other astrophysical studies - detecting radio emissions from other stars or galaxies - to see if they contain any technical signals, and make that a standard practice," says Grimaldi.
The research has been published in The Astronomical journal.
Astronomers have found for the first time the remnants of the first stars in the universe in distant gas clouds
Astronomers have discovered chemical remnants left behind by the first stars in the universe after they died in massive cosmic explosions called supernovae.
And using the Very Large Telescope (VLT) located in the Atacama Desert in northern Chile. Scientists have found, for the first time, the fingerprints left by the explosion of the first stars in the universe in distant gas clouds.
Astronomers indicated that they discovered three distant gas clouds whose chemical composition matches what would be expected from the first stellar explosions.
This discovery could help scientists better understand the conditions of the universe shortly after the Big Bang, when the universe was about 300,000 years old and the first stars were born.
"We detected three distant gas clouds with a chemical signature that matches what we would expect from the first stellar explosions," study leader Dr. Andrea Sacardi of the Observatoire de Paris told Space.com by email.
Study co-author Stefania Salvadori, associate professor in the Department of Physics and Astronomy at the University of Florence, explained to Space.com: The new findings offer a way to study this first generation of stars indirectly. We can use these studies to complement stellar archaeology and reveal the nature of the first stars and the first supernovae."
The first generation of stars that formed 13.5 billion years ago was very different from the stellar objects we see in the universe today. That's because they were born when the universe was mostly filled with hydrogen and helium, with only traces of the heavy elements, which astronomers call "metals."
As a result, these stars were rich in hydrogen and helium but also poor in metals.
These stars, thought to be tens or hundreds of times more massive than our sun, died quickly in powerful explosions known as supernovae, enriching the surrounding gas with heavier elements. This led to the distribution of the constituent elements in this first generation of stars, such as carbon, oxygen and magnesium, found in the stars' outer layers, into the universe. This material then became the building blocks for the second generation of stars.
As a result, the star's cores collapsed while the outer layers were blown away in a massive supernova explosion. Thus, stars descended from earlier stellar bodies are richer in heavier elements, and when stars are born later in the 13.8-billion-year-old history of the universe, they become progressively less metal-poor.
Despite their enormous power, these first supernovae were still too weak to scatter the very heavy elements such as iron found primarily in the cores of these first stars.
So, when astronomers search for the chemical remains of these early and second-generation stars, they're looking for lots of carbon and other elements mixed in with very little iron.
Find the first astral ash
To search for the chemical signatures of these first stars that exploded as low-energy supernovae, the team looked for distant gaseous clouds that are poor in iron but rich in other elements. They found three distant clouds in the early universe that contained very little iron but plenty of carbon and other elements, the signature of the explosions of the first stars.
This strange chemical composition was also observed in many ancient stars in our galaxy, which scientists consider to be second-generation stars that formed directly from the "ashes" of the first stars.
And this new study finds just such ash in the early universe. "Our discovery opens up new ways to indirectly study the nature of the first stars," Salvadori explains.
To discover and study these distant gas clouds, he used the light from quasars, which are extremely bright sources powered by supermassive black holes at the centers of distant galaxies. As the light from the quasar travels through the universe, it passes through clouds of gas where different chemical elements leave an imprint on the light.
"These distant clouds in the early universe have a very low percentage of iron but a lot of carbon and other light elements," Sacardi said. "In fact, in the Milky Way, many ancient stars show a small content of iron and a large excess of carbon and other light elements." Others like our gas withdrawal."
Salvadori added that these chemical signals from the first stars may have so far evaded detection because the search for them focused on the dense gas clouds that could sustain star formation after the gas was enriched by the first supernovae.
"In other words, later generations of more metal-rich, ordinary supernovae were able to further pollute these dense gas clouds, thus erasing the chemical fingerprints of the first stars," Salvadori said. "Instead we analyzed the chemical composition of the more diffuse gas clouds and identified the signatures of the first stars. This success." It is the result of a close collaboration between theory and observations."
The team indicated that they will now try to better understand the nature of these gas clouds and aim to discover the extent of their spread throughout the history of the universe.
The study results were published May 3 in The Astrophysical Journal.
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