When sailing along on the seas and you suddenly spot a porpoise's fin in the distance, chances are that you have only encountered a single animal. Porpoises are most often seen alone, but new research now suggests that they also roam in groups—and even enter into a sophisticated collaboration when hunting. "The way they collaborate surprises us, because the common perception among biologists is that porpoises roam and hunt alone," says Associate Professor Magnus Wahlberg, who is an expert in marine mammals and heads the Marine Biological Research Centre at the University of Southern Denmark (SDU). Drone footage has revealed group hunting among porpoises coming together to hunt schools of fish. The research team has recorded almost 44 hours of drone footage from the waters around Funen, corresponding to 159 hunting sequences. In 95 of these, between two and six adult porpoises participated. The researchers expected to see the porpoises hunting alone. And if it turned out that several porpoises were in fact hunting together, the researchers expected that it would be an unstructured hunt without no cooperation whatsoever between the individual animals. "Instead, a seemingly solitary animal has turned out to be more social than previously thought," says Ph.D. student Sara Torres Ortiz, who was at SDU when the research was conducted but is now at the Max Planck Institute for Ornithology in Germany. She researches animal cognition. The footage also shows porpoises hunting alone. According to the researchers, solitary hunters are less successful at foraging food than the porpoises that hunt in groups. In order to hunt in the observed way, the porpoises must be able to share information and coordinate their actions. They take on different roles during the hunt, and the drone footage has revealed six different roles: The distant gatherer (far bordering) swims around the school of fish at a distance of at least three body lengths. The close gatherer (close bordering) swims around the school of fish at a distance closer than three body lengths and with its body and head parallel to the school of fish. The shepherd (herding fish) swims close to the school of fish and influences its direction. The splitter (cross school) swims through the school The spear (hunting attempt) swims directly into the school at high speed Swimming away—swims away from the school. Each porpoise can take on different roles during the hunt, and the result of the collaboration is that the school of fish eventually becomes so confused and exhausted that the individual hunters are able to capture the fish that stray away from the school. Play 00:00 01:05 Mute Settings PIP Enter fullscreen Play Drone video of porpoises group hunting. Credit: Anders Boe/University of Southern Denmark "There are several different types of group hunting in the animal kingdom. The form observed can be called a form of collaborative hunting, and it is more sophisticated than the form called cooperative hunting," explains Ortiz. Animals such as chimpanzees and raves exhibit cooperative hunting abilities. During this form of hunting, several hunters gather without taking on different roles. The collaborative hunt, in which the individual hunters take on different roles, is more rare—or, rather: It is not observed very often because it is inherently difficult to follow. The use of drones opens up new possibilities of following a herd of animals from above—like this porpoise study—and this may in the future contribute with new and improved knowledge about hunting animals. Until now, collaborative hunting has been scientifically described in animals such as lions, fossas, wolves and jackals. Wolves and jackals divide the hunting pack into two teams, where one team lurks while the other team drives the prey forward. Among lions, the strategy is for the entire pack to approach the prey from different directions, after which some hunters lie down to hide while the rest of the group drives the prey towards them. Sea-dwelling predators are extra difficult to observe, meaning researchers cannot say with certainty whether animals like killer whales and dolphins hunt cooperatively and/or collaboratively. However, several researchers have observed complex hunting behaviors in killer whales and dolphins. For example, killer whales have been seen making waves that push seals off ice floes. What other surprises await? The drone footage now raises new questions: https://phys.org/news/2021-06-porpoises-cooperate-surprisingly-sophisticated-group.html
7Upvotes
thumb_upthumb_downchat_bubble

More from 777 times

Blue whales may be the biggest animals in the world, but they're also some of the hardest to find. Not only are they rare (it's estimated that less than 0.15 percent of blue whales in the Southern Hemisphere survived whaling), they're also reclusive by nature and can cover vast areas of ocean. But now, a team of scientists led by UNSW Sydney are confident they've discovered a new population of pygmy blue whales, the smallest subspecies of blue whales, in the Indian Ocean. And it was the whales' powerful singing—recorded by underwater bomb detectors—that gave them away. "We've found a whole new group of pygmy blue whales right in the middle of the Indian Ocean," says UNSW Professor Tracey Rogers, marine ecologist and senior author of the study. "We don't know how many whales are in this group, but we suspect it's a lot by the enormous number of calls we hear." The discovery was made possible using data from the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), an organization that monitors international nuclear bomb testing. Since 2002, the CTBTO have been using advanced underwater microphones (called 'hydrophones') to detect soundwaves from potential nuclear bomb tests. The recordings—which pick up many other detailed ocean sounds—are available to scientists to use for their marine science research. The UNSW-led team were studying the data when they found an unusually strong signal: a whale song that had previously been identified in the recordings, but that scientists still knew little about. After closely studying its composition (details like the song's structure, frequency and tempo), they realized that it belonged to a group of pygmy blue whales—but not any of the ones previously recorded in the area. "I think it's pretty cool that the same system that keeps the world safe from nuclear bombs allows us to find new whale populations, which long-term can help us study the health of the marine environment," says Prof. Rogers. Pygmy blue whales are the smallest members of the blue whale family, but that's the only small thing about them: they can reach up to 24 meters' long, which is almost the length of two standard buses. If visual sightings confirm this new population, they would become the fifth population of pygmy blue whales to be discovered in the Indian Ocean. The findings, recently published in Scientific Reports, have come in time for World Oceans Day. "Blue whales in the Southern Hemisphere are difficult to study because they live offshore and don't jump around—they're not show-ponies like the humpback whales," says Prof. Rogers. "Without these audio recordings, we'd have no idea there was this huge population of blue whales out in the middle of the equatorial Indian Ocean." A chorus of whales Dr. Emmanuelle Leroy, the lead author of the study and former postdoctoral researcher at UNSW Science, is a bioacoustician—someone who studies how animals create and receive sounds. She was studying the CTBTO data when she noticed a peculiar pattern emerging. "At first, I noticed a lot of horizontal lines on the spectrogram," says Dr. Leroy. "These lines at particular frequencies reflect a strong signal, so there was a lot of energy there." To find out if the signal was a random blip or something more, Dr. Leroy and the team scanned 18 years' worth of CTBTO data—the entire available dataset since the recording started—to look for any wider patterns. They found the songs weren't just a random occurrence. "Thousands of these songs were being produced every year," she says. "They formed a major part of the ocean's acoustic soundscape. "The songs couldn't have just been coming from a couple of whales—they had to be from an entire population." Even though blue whales like to travel undetected, they can give away their identities by the type of melody they sing. Credit: Shutterstock Singing a simple tune Like many other whales, blue whales are powerful singers: scientists estimate their songs can travel anywhere between 200 and 500 kilometers. These songs are very low frequency (barely audible to the human ear) and have a different structure to other whales' songs. "Humpback whales are like jazz singers," says Prof. Rogers. "They change their songs all the time. "Blue whales, on the other hand, are more traditional. They sing very structured, simple songs." Music style can even change within a whale species: each of the known pygmy blue whale populations in the Indian Ocean sing slightly different melodies. Prof. Rogers says these musical differences are similar to generational slang between humans. "We still don't know whether they're born with their songs or whether they've learnt it," she says. "But it's fascinating that within the Indian Ocean you have animals intersecting with one another all the time but whales from different regions still retain their distinctive songs. Their songs are like a fingerprint that allows us to track them as they move over thousands of kilometers." Dr. Leroy compared the acoustic features of the song with the three other blue whale song-types known in the Indian Ocean, as well as with four types of Omura's whale songs (another whale in the area) – but the evidence pointed towards this being an entirely new population of blue whales. The team named the newly-found population "Chagos," after the archipelago they were detected nearby. "We suspect that the whales singing the Chagos song move at different times across the Indian Ocean," says Prof. Rogers. "We found them not only in the central Indian Ocean, but as far north as the Sri Lankan coastline and as far east in the Indian Ocean as the Kimberley coast in northern Western Australia." While the team are confident in their findings, Dr. Leroy says it's impossible to confirm the species without a visual observation. Visual sightings for such an elusive animal can be tricky and expensive to fund, so it's unlikely this will be verified anytime soon. "If it isn't a blue whale, it definitely sings like one," says Dr. Leroy. A big find for conservation The finding is big news for marine conservation, as blue whales were brought to the edge of extinction after whaling in the 20th century. And unlike many other types of whales in the Southern Hemisphere, their numbers haven't sprung back. "Discovering a new population is the first step to protecting it," says Dr. Leroy. Acoustic information hidden in whale songs can also teach us more about the animals, like their spatial distribution, migration patterns and population numbers. A previous study led by Dr. Leroy even found the changing pitch of blue whales' songs could be a response the noise of cracking icebergs. Prof. Rogers is now leading a team using the CTBTO data to study how the Chagos population has changed over time. The findings could teach us how the whales adapted to warming ocean temperatures over the past 18 years—and how they might fare moving into the future. "The largest animal in the world is one of the hardest ones to actually study," says Prof. Rogers. "There are many more of these blue whales out there than we've realized—and we've only been able to find them with the help of this international infrastructure." https://phys.org/news/2021-06-population-blue-whales-detectors.html
58 views ·
In a dramatic, multi-staged eruption, the sun has revealed new clues that could help scientists solve the long-standing mystery of what causes the sun's powerful and unpredictable eruptions. Uncovering this fundamental physics could help scientists better predict the eruptions that cause dangerous space weather conditions at Earth. This explosion contained components of three different types of solar eruptions that usually occur separately—making it the first time such an event has been reported. Having all three eruption types together in one event provides scientists with something of a solar Rosetta Stone, allowing them to translate what they know about each type of solar eruption to understand other types and uncover an underlying mechanism that could explain all types of solar eruptions. "This event is a missing link, where we can see all of these aspects of different types of eruptions in one neat little package," said Emily Mason, lead author on the new study and solar scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "It drives home the point that these eruptions are caused by the same mechanism, just at different scales." Eruptions on the sun usually come in one of three forms: a coronal mass ejection, a jet, or a partial eruption. Coronal mass ejections—CMEs—and jets are both explosive eruptions that cast energy and particles into space, but they look very different. While jets erupt as narrow columns of solar material, CMEs form huge bubbles that expand out, pushed and sculpted by the sun's magnetic fields. Partial eruptions, on the other hand, start erupting from the surface but don't conjure enough energy to leave the sun, so most of the material falls back down onto the solar surface. An unusual eruption on the Sun may offer clues to understanding our star’s mysterious explosions. The new research studied an event named the “Rosetta Stone'' of solar eruptions. Just as the Rosetta Stone was the key to understanding Egyptian hieroglyphics, studying this eruption could be the key to understanding all types of solar eruptions. Credit: NASA/Mara Johnson-Groh/Haley Reed In this eruption—observed with NASA's Solar Dynamics Observatory and the European Space Agency and NASA's Solar and Heliospheric Observatory on March 12 and 13, 2016—the scientists saw the ejection of a hot layer of solar material above a magnetically active region on the sun's surface. The ejection was too big to be a jet, but too narrow to be a CME. Within a half an hour, a second cooler layer of material on the surface also started to erupt from the same place, but ultimately it fell back down as a partial eruption. Seeing an eruption with both jet and CME characteristics tells scientists they're likely caused by a singular mechanism. With this new understanding, scientists can apply what they know about jets to CMEs. The event also tells scientists that partial eruptions occur on the same spectrum but encounter some yet-unknown limiter that restricts their energy and doesn't allow them to make it off the sun. Understanding the mechanism behind these events, especially CMEs, is of critical importance to predicting when a large eruption might cause disruptions at Earth. CMEs in particular release large clouds of high-energy charged particles and magnetic fields that stream out across the solar system and can result in the space weather—a storm of high-energy particles and activity that can be dangerous to astronauts and technology in space and, in extreme cases, utility grids on Earth. By modeling the new Rosetta eruption and others since discovered like it, the scientists hope they can figure out what root mechanism causes solar eruptions and determines their characteristics. Finding a trigger could ultimately allow scientists to predict when a large eruption could threaten Earth and Mars several hours in advance—providing enough time for astronauts and spacecraft operators to take precautionary measures. The new study was presented on June 7, 2021, by Mason at the AAS 238 meeting and has been accepted for publication in Astrophysical Journal Letters. https://phys.org/news/2021-06-rosetta-stone-eruption-sun-solar.html
54 views ·
We must also keep in mind several Countries have their own UFOs (secret) especially the USA, Russia, and China which may account for many sightings worldwide .. The US military has released previously classified photos and films related to unidentified flying object (UFO) sightings, which mostly show something blurry moving strangely. Still, I hear that a friend of a friend has gone from thinking there's a 1% chance that UFOs are aliens to now believing it is 50%. Is he rational? People are constantly seeing things in the sky they don't understand. The vast majority are airplanes, satellites, weather balloons, clouds, rocket launches, auroras, optical reflections and so on. But for some sightings, there's no known explanation. The problem is that people jump to the conclusion "unknown = aliens". And when you think about it, this is fairly odd. Why not angels? Anyway, I like to do maths instead. The Bayes formula (below), a mainstay of statistics, gives the probability (Pr) of something, given some evidence. Spelled out, it says that the probability that UFOs are aliens given some evidence is equal to how likely it is that the evidence would appear if UFOs really were aliens, times how likely it is that there are aliens. That needs to be divided by how likely the actual evidence is, which is notoriously difficult to work out. But what we are really interested in is if the evidence tells us we should believe in aliens compared to not believing in aliens. We can do this by dividing the equation above with the counterpart for UFOs not being aliens: When we do this, we also get rid of that pesky factor for how probable the evidence is. The equation now shows how likely it is that UFOs are aliens compared to how likely it is that they are not—after looking at the footage. The result will be one if the options are equally likely, and high if aliens are the stronger bet. It tells us how we should update our beliefs based on new evidence. There are two factors in the equation. One (second bracket) is how likely we think aliens are. Some might say 50:50, making this factor one, while others may make it very low, like 10-23. This is a statement of belief based on knowledge of the world (using for example the famous Drake equation). This needs to be multiplied by another factor (first bracket), often called the Bayes factor. It denotes how specific the evidence we see is for aliens v no aliens. If I meet a little green blob claiming to be from Epsilon Eridani, that is relatively specific (but could still somewhat be explained by a prank or me being mad). In this case, the factor may be much bigger than 1 and I get to shift towards thinking there are aliens. If I see a mysterious blob of light in the sky that could be aliens but could also be a lot of other things, then the factor would not be much different from 1—the evidence is as specific for aliens as it is for no aliens, and I don't get much change in belief. In other words, specificity is hugely important. Weird and unknown things may happen, but if the lights could equally well be faeries, intrusions from the fifth dimension, swamp gas, Chinese drones, sapient octopuses, or anything else, the Bayes factor will still be close to 1. That the world is strange is not evidence for aliens. My verdict https://phys.org/news/2021-06-ufos-odds-alien-spaceship.html
55 views ·

More from 777 times

Blue whales may be the biggest animals in the world, but they're also some of the hardest to find. Not only are they rare (it's estimated that less than 0.15 percent of blue whales in the Southern Hemisphere survived whaling), they're also reclusive by nature and can cover vast areas of ocean. But now, a team of scientists led by UNSW Sydney are confident they've discovered a new population of pygmy blue whales, the smallest subspecies of blue whales, in the Indian Ocean. And it was the whales' powerful singing—recorded by underwater bomb detectors—that gave them away. "We've found a whole new group of pygmy blue whales right in the middle of the Indian Ocean," says UNSW Professor Tracey Rogers, marine ecologist and senior author of the study. "We don't know how many whales are in this group, but we suspect it's a lot by the enormous number of calls we hear." The discovery was made possible using data from the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), an organization that monitors international nuclear bomb testing. Since 2002, the CTBTO have been using advanced underwater microphones (called 'hydrophones') to detect soundwaves from potential nuclear bomb tests. The recordings—which pick up many other detailed ocean sounds—are available to scientists to use for their marine science research. The UNSW-led team were studying the data when they found an unusually strong signal: a whale song that had previously been identified in the recordings, but that scientists still knew little about. After closely studying its composition (details like the song's structure, frequency and tempo), they realized that it belonged to a group of pygmy blue whales—but not any of the ones previously recorded in the area. "I think it's pretty cool that the same system that keeps the world safe from nuclear bombs allows us to find new whale populations, which long-term can help us study the health of the marine environment," says Prof. Rogers. Pygmy blue whales are the smallest members of the blue whale family, but that's the only small thing about them: they can reach up to 24 meters' long, which is almost the length of two standard buses. If visual sightings confirm this new population, they would become the fifth population of pygmy blue whales to be discovered in the Indian Ocean. The findings, recently published in Scientific Reports, have come in time for World Oceans Day. "Blue whales in the Southern Hemisphere are difficult to study because they live offshore and don't jump around—they're not show-ponies like the humpback whales," says Prof. Rogers. "Without these audio recordings, we'd have no idea there was this huge population of blue whales out in the middle of the equatorial Indian Ocean." A chorus of whales Dr. Emmanuelle Leroy, the lead author of the study and former postdoctoral researcher at UNSW Science, is a bioacoustician—someone who studies how animals create and receive sounds. She was studying the CTBTO data when she noticed a peculiar pattern emerging. "At first, I noticed a lot of horizontal lines on the spectrogram," says Dr. Leroy. "These lines at particular frequencies reflect a strong signal, so there was a lot of energy there." To find out if the signal was a random blip or something more, Dr. Leroy and the team scanned 18 years' worth of CTBTO data—the entire available dataset since the recording started—to look for any wider patterns. They found the songs weren't just a random occurrence. "Thousands of these songs were being produced every year," she says. "They formed a major part of the ocean's acoustic soundscape. "The songs couldn't have just been coming from a couple of whales—they had to be from an entire population." Even though blue whales like to travel undetected, they can give away their identities by the type of melody they sing. Credit: Shutterstock Singing a simple tune Like many other whales, blue whales are powerful singers: scientists estimate their songs can travel anywhere between 200 and 500 kilometers. These songs are very low frequency (barely audible to the human ear) and have a different structure to other whales' songs. "Humpback whales are like jazz singers," says Prof. Rogers. "They change their songs all the time. "Blue whales, on the other hand, are more traditional. They sing very structured, simple songs." Music style can even change within a whale species: each of the known pygmy blue whale populations in the Indian Ocean sing slightly different melodies. Prof. Rogers says these musical differences are similar to generational slang between humans. "We still don't know whether they're born with their songs or whether they've learnt it," she says. "But it's fascinating that within the Indian Ocean you have animals intersecting with one another all the time but whales from different regions still retain their distinctive songs. Their songs are like a fingerprint that allows us to track them as they move over thousands of kilometers." Dr. Leroy compared the acoustic features of the song with the three other blue whale song-types known in the Indian Ocean, as well as with four types of Omura's whale songs (another whale in the area) – but the evidence pointed towards this being an entirely new population of blue whales. The team named the newly-found population "Chagos," after the archipelago they were detected nearby. "We suspect that the whales singing the Chagos song move at different times across the Indian Ocean," says Prof. Rogers. "We found them not only in the central Indian Ocean, but as far north as the Sri Lankan coastline and as far east in the Indian Ocean as the Kimberley coast in northern Western Australia." While the team are confident in their findings, Dr. Leroy says it's impossible to confirm the species without a visual observation. Visual sightings for such an elusive animal can be tricky and expensive to fund, so it's unlikely this will be verified anytime soon. "If it isn't a blue whale, it definitely sings like one," says Dr. Leroy. A big find for conservation The finding is big news for marine conservation, as blue whales were brought to the edge of extinction after whaling in the 20th century. And unlike many other types of whales in the Southern Hemisphere, their numbers haven't sprung back. "Discovering a new population is the first step to protecting it," says Dr. Leroy. Acoustic information hidden in whale songs can also teach us more about the animals, like their spatial distribution, migration patterns and population numbers. A previous study led by Dr. Leroy even found the changing pitch of blue whales' songs could be a response the noise of cracking icebergs. Prof. Rogers is now leading a team using the CTBTO data to study how the Chagos population has changed over time. The findings could teach us how the whales adapted to warming ocean temperatures over the past 18 years—and how they might fare moving into the future. "The largest animal in the world is one of the hardest ones to actually study," says Prof. Rogers. "There are many more of these blue whales out there than we've realized—and we've only been able to find them with the help of this international infrastructure." https://phys.org/news/2021-06-population-blue-whales-detectors.html
58 views ·
In a dramatic, multi-staged eruption, the sun has revealed new clues that could help scientists solve the long-standing mystery of what causes the sun's powerful and unpredictable eruptions. Uncovering this fundamental physics could help scientists better predict the eruptions that cause dangerous space weather conditions at Earth. This explosion contained components of three different types of solar eruptions that usually occur separately—making it the first time such an event has been reported. Having all three eruption types together in one event provides scientists with something of a solar Rosetta Stone, allowing them to translate what they know about each type of solar eruption to understand other types and uncover an underlying mechanism that could explain all types of solar eruptions. "This event is a missing link, where we can see all of these aspects of different types of eruptions in one neat little package," said Emily Mason, lead author on the new study and solar scientist at NASA's Goddard Space Flight Center in Greenbelt, Maryland. "It drives home the point that these eruptions are caused by the same mechanism, just at different scales." Eruptions on the sun usually come in one of three forms: a coronal mass ejection, a jet, or a partial eruption. Coronal mass ejections—CMEs—and jets are both explosive eruptions that cast energy and particles into space, but they look very different. While jets erupt as narrow columns of solar material, CMEs form huge bubbles that expand out, pushed and sculpted by the sun's magnetic fields. Partial eruptions, on the other hand, start erupting from the surface but don't conjure enough energy to leave the sun, so most of the material falls back down onto the solar surface. An unusual eruption on the Sun may offer clues to understanding our star’s mysterious explosions. The new research studied an event named the “Rosetta Stone'' of solar eruptions. Just as the Rosetta Stone was the key to understanding Egyptian hieroglyphics, studying this eruption could be the key to understanding all types of solar eruptions. Credit: NASA/Mara Johnson-Groh/Haley Reed In this eruption—observed with NASA's Solar Dynamics Observatory and the European Space Agency and NASA's Solar and Heliospheric Observatory on March 12 and 13, 2016—the scientists saw the ejection of a hot layer of solar material above a magnetically active region on the sun's surface. The ejection was too big to be a jet, but too narrow to be a CME. Within a half an hour, a second cooler layer of material on the surface also started to erupt from the same place, but ultimately it fell back down as a partial eruption. Seeing an eruption with both jet and CME characteristics tells scientists they're likely caused by a singular mechanism. With this new understanding, scientists can apply what they know about jets to CMEs. The event also tells scientists that partial eruptions occur on the same spectrum but encounter some yet-unknown limiter that restricts their energy and doesn't allow them to make it off the sun. Understanding the mechanism behind these events, especially CMEs, is of critical importance to predicting when a large eruption might cause disruptions at Earth. CMEs in particular release large clouds of high-energy charged particles and magnetic fields that stream out across the solar system and can result in the space weather—a storm of high-energy particles and activity that can be dangerous to astronauts and technology in space and, in extreme cases, utility grids on Earth. By modeling the new Rosetta eruption and others since discovered like it, the scientists hope they can figure out what root mechanism causes solar eruptions and determines their characteristics. Finding a trigger could ultimately allow scientists to predict when a large eruption could threaten Earth and Mars several hours in advance—providing enough time for astronauts and spacecraft operators to take precautionary measures. The new study was presented on June 7, 2021, by Mason at the AAS 238 meeting and has been accepted for publication in Astrophysical Journal Letters. https://phys.org/news/2021-06-rosetta-stone-eruption-sun-solar.html
54 views ·
We must also keep in mind several Countries have their own UFOs (secret) especially the USA, Russia, and China which may account for many sightings worldwide .. The US military has released previously classified photos and films related to unidentified flying object (UFO) sightings, which mostly show something blurry moving strangely. Still, I hear that a friend of a friend has gone from thinking there's a 1% chance that UFOs are aliens to now believing it is 50%. Is he rational? People are constantly seeing things in the sky they don't understand. The vast majority are airplanes, satellites, weather balloons, clouds, rocket launches, auroras, optical reflections and so on. But for some sightings, there's no known explanation. The problem is that people jump to the conclusion "unknown = aliens". And when you think about it, this is fairly odd. Why not angels? Anyway, I like to do maths instead. The Bayes formula (below), a mainstay of statistics, gives the probability (Pr) of something, given some evidence. Spelled out, it says that the probability that UFOs are aliens given some evidence is equal to how likely it is that the evidence would appear if UFOs really were aliens, times how likely it is that there are aliens. That needs to be divided by how likely the actual evidence is, which is notoriously difficult to work out. But what we are really interested in is if the evidence tells us we should believe in aliens compared to not believing in aliens. We can do this by dividing the equation above with the counterpart for UFOs not being aliens: When we do this, we also get rid of that pesky factor for how probable the evidence is. The equation now shows how likely it is that UFOs are aliens compared to how likely it is that they are not—after looking at the footage. The result will be one if the options are equally likely, and high if aliens are the stronger bet. It tells us how we should update our beliefs based on new evidence. There are two factors in the equation. One (second bracket) is how likely we think aliens are. Some might say 50:50, making this factor one, while others may make it very low, like 10-23. This is a statement of belief based on knowledge of the world (using for example the famous Drake equation). This needs to be multiplied by another factor (first bracket), often called the Bayes factor. It denotes how specific the evidence we see is for aliens v no aliens. If I meet a little green blob claiming to be from Epsilon Eridani, that is relatively specific (but could still somewhat be explained by a prank or me being mad). In this case, the factor may be much bigger than 1 and I get to shift towards thinking there are aliens. If I see a mysterious blob of light in the sky that could be aliens but could also be a lot of other things, then the factor would not be much different from 1—the evidence is as specific for aliens as it is for no aliens, and I don't get much change in belief. In other words, specificity is hugely important. Weird and unknown things may happen, but if the lights could equally well be faeries, intrusions from the fifth dimension, swamp gas, Chinese drones, sapient octopuses, or anything else, the Bayes factor will still be close to 1. That the world is strange is not evidence for aliens. My verdict https://phys.org/news/2021-06-ufos-odds-alien-spaceship.html
55 views ·