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We’ll Have to Wait About 3,000 Years for a Reply From Intelligent Civilizations – Universe Today

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As a field, the Search for Extraterrestrial Intelligence suffers from some rather significant constraints. Aside from the uncertainty involved (e.g., is there life beyond Earth we can actually communicate with?), there are the limitations imposed by technology and the very nature of space and time. For instance, scientists are forced to contend with the possibility that by the time a message is received by an intelligent species, the civilization that sent it will be long dead.

Harvard astronomers Amir Siraj and Abraham Loeb tackle this very question in a new study that recently appeared online. Taking their cue from the Copernican Principle, which states that humanity and Earth are representative of the norm (and not an outlier), they calculated that if any transmissions from Earth were heard by an extraterrestrial technological civilization (ETC), it would take about 3000 years to get a reply.

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Their stud, titled “Intelligent Responses to Our Technological Signals Will Not Arrive In Fewer Than Three Millennia,” recently appeared online and is being considered for publication. Whereas Siraj is a concurrent undergraduate and graduate student of astrophysics at Harvard, Prof. Loeb is the Frank B. Baird Jr. Professor of Science, the Director of Harvard’s Institute for Theory and Computation (ITC), the Chair of the Breakthrough Starshot Advisory Committee, a bestselling author, and Siraj’s academic advisor.

The globally distributed dishes of the European VLBI Network are linked with each other and the 305-m William E. Gordon Telescope at the Arecibo Observatory in Puerto Rico. Credit: Danielle Futselaar

Loeb is also renowned for theorizing that the interstellar object ‘Oumuamua, which flew past Earth in 2017, could have been extraterrestrial lightsail. This theory was originally put forth in a 2018 paper he co-wrote with postdoctoral researcher Shmuel Bialy (of the ITC). The arguments presented therein have since been expanded upon in Loeb’s most recent book, Extraterrestrial: The First Sign of Intelligent Life Beyond Earth.

Prof. Loeb recently partnered with Dr. Frank Laukien and other colleagues to launch the Galileo Project, a multinational non-profit dedicated to the study of Unidentified Aerial Phenomena (UAPs). Siraj serves as the Director of Interstellar Object Studies for this project, and he and Loeb have published extensively on subjects ranging from black holes and meteors to panspermia and interstellar objects (many of which were on the subject of ‘Oumuamua).

For the sake of this study, Siraj and Loeb focused on a particular aspect of SETI, which they dubbed the Search for Extraterrestrial Responding Intelligence (SETRI). By this, they mean ETIs that would be motivated to message Earth in response to the detection of technological activity on our planet (aka. “technosignatures”). This addresses a question of growing importance to the SETI community.

In short, does humanity have a chance of ever hearing from an ETC before our civilization collapses or is wiped out by a natural disaster? As Siraj told Universe Today via email:

“It is important to estimate the response time from extraterrestrial responding intelligences (ETRIs) since such an estimate informs the nature of effective SETI searches — as well the implications of a confirmed signal if we ever receive one. The question we try to answer in our paper is: when might we expect our first cosmic conversation to take place?”

This artist’s impression shows the planet Proxima b orbiting the red dwarf star Proxima Centauri, the closest star to the Solar System. Credit: ESO/M. Kornmesser

This establishes the first parameter of their study, which was the amount of time that humanity has been emitting detectable signatures. Of all potential technosignatures that have been considered to date, the most likely and most widely investigated by SETI researchers are still radio transmissions. In keeping with the Copernican Principle, we can assume that ETIs are also engaged in the search for signs of intelligence other than their own.

“The Copernican principle asserts that we are unlikely to live at a privileged time and so the likelihood of another habitable planet like Earth going right now through an analog of our first century of radio communication, given a few billion years of its history, is below one part in ten million,” said Loeb. “Therefore, a response is expected only within a large enough volume, containing more than ten million stars.”

It can also be safely assumed that an ETI would see radio signals as a possible technosignature and would be actively listening for them. The first long-range radio broadcast took place in 1901, when Italian inventor Guglielmo Marconi sent the first transatlantic broadcast from Cornwall, England, to St. John’s, Newfoundland. Since then, humans have been sending radio transmissions to space without thinking about the consequences.

This means that if there is a civilization within a hundred light-years of Earth with sensitive radio telescopes, they may have already heard from us. In short, we may have already “started a conversation” with an intelligent species and are just waiting for a response. Beyond this, said Siraj, they went with a number of parameters that were consistent with the Copernican Principle and the conditions under which life is known to flourish:

“[W]e considered ETIs able to communicate via electromagnetic radiation, located on Earth-like planets orbiting Sun-like stars (aka, “life as we know it”). Furthermore, we considered radio signals (which at the speed of light) as well as physical probes, which would travel slower. We used the Copernican principle, which is inherently optimistic about the prevalence of life in the Universe, to establish a lower limit on the expected response time from ETRIs.

In this illustration, NASA’s Hubble Space Telescope is looking along the paths of NASA’s Voyager 1 and 2 spacecraft as they journey through the solar system and into interstellar space. Credit: NASA/ESA/Z. Levy (STScI).

Transmission technologies can extend beyond radio waves to include other types of electromagnetic (EM) radiation, such as microwave lasers, X-rays, gamma-rays, and more. Since the only constraint is the speed of light – 299,792,458 m/s (1079 million km/h; 670.6 million mph) – it remains the fastest available option. It also means humans would only need to wait until the 22nd century for a transmission from a civilization located a hundred light-years away.

That being said, it is also possible that an ETC would choose to explore our planet more closely rather than send a transmitted reply. In this respect, Siraj and Loeb considered possibilities like the Voyager 1 and 2 missions, New Horizons, and the Pioneer 10 and 11 spacecraft. All of these robotic missions have or will enter interstellar space (or will in the near future) and could someday be intercepted by an ETC.

It was for this reason that the Pioneer Plaques and the Golden Records were created. However, it will take millions of years before any of these missions reach even the closest star systems to Earth. This means that if a civilization sent a probe to investigate Earth in response to radio signals from a hundred years ago, it wouldn’t arrive for hundreds of thousands of years. As Loeb explained:

“Although the latter response method results in physical contact with alien objects, it requires millions of years for the journey across a hundred light-years. This means that we still have a waiting time as long as the time that has elapsed since humans first appeared on Earth before we will witness chemically-propelled crafts in response to our radio broadcasts.”

This graphic shows the relative positions of NASA’s most distant spacecraft in early 2011, looking at the solar system from the side. Credit: NASA/JPL-Caltech

Other possible concepts, like directed-energy propulsion (a la Breakthrough Starshot), could make the transit in much less time – at 20% the speed of light, it would reach Alpha Centauri in just 20 years. However, such concepts are effective for reaching the nearest star systems, but not stars 1000 light-years away within a reasonable timeline. As a final parameter, they considered just how many planets out there are likely to host an ETC.

“The Copernican principle asserts that we are unlikely to live at a privileged time and so the likelihood of another habitable planet like Earth going right now through an analog of our first century of radio communication, given a few billion years of its history, is below one part in ten million,” said Loeb. Working from this, they determined that a response could only be expected within a large enough volume, containing more than ten million stars.

Assuming that our galaxy is relatively homogenous in terms of the distribution of stars in its disk, this results in a volume of 1 billion cubic light-years (ly3) or one thousand light-years in any direction. This, in turn, entails a two-way travel time of more than two thousand years. This essentially means that if an ETC is aware of us and wants to talk, we would not be hearing from them until 4000 CE at the earliest. Or as Siraj summarized:

“We found that the fact that we have only existed as a technological civilization for about a hundred years means that, right now, we should not expect to hear back from an extraterrestrial civilization in response to our own signals. In other words, it’s extraordinarily unlikely that we could start a cosmic conversation.”

An artist’s illustration of a light-sail powered by a radio beam (red) generated on the surface of a planet. Credit: M. Weiss/CfA

This conclusion is supported by previous research (conducted with the help of Dr. Frank Drake himself!) that indicated that within various parameters, a call-and-answer scenario would take longer than the average civilization’s lifespan. In other words, any signals we receive from an ETC (whether they are a response or an attempt to “start a conversation”) are likely to have been sent by a species that has since become extinct.

This, according to Siraj, is the most significant aspect of their study, which is that civilizations have a life expectancy (which they have a measure of control over). In essence, it underscores the importance of ensuring that humanity doesn’t succumb to self-destruction or a cataclysmic fate. “The big takeaway here is that we’d better get our act together and figure out how to survive long-term if we ever want to participate in a cosmic conversation!”

Further Reading: arXiv

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Giant prehistoric salmon had tusk-like teeth for defence, building nests: study – CP24

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Brenna Owen, The Canadian Press


Published Wednesday, April 24, 2024 7:27PM EDT


Last Updated Wednesday, April 24, 2024 7:27PM EDT

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The artwork and publicity materials showcasing a giant salmon that lived five million years ago were ready to go to promote a new exhibit, when the discovery of two fossilized skulls immediately changed what researchers knew about the fish.

Initial fossil discoveries of the 2.7-metre-long salmon in Oregon in the 1970s were incomplete and had led researchers to mistakenly suggest the fish had fang-like teeth.

It was dubbed the “sabre-toothed salmon” and became a kind of mascot for the Museum of Natural and Cultural History at the University of Oregon, says researcher Edward Davis.

But then came discovery of two skulls in 2014.

Davis, a member of the team that found the skulls, says it wasn’t until they got back to the lab that he realized the significance of the discovery that has led to the renaming of the fish in a new, peer-reviewed study.

“There were these two skulls staring at me with sideways teeth,” says Davis, an associate professor in the department of earth sciences at the university.

In that position, the tusk-like teeth could not have been used for biting, he says.

“That was definitely a surprising moment,” says Davis, who serves as director of the Condon Fossil Collection at the university’s Museum of Natural and Cultural History.

“I realized that all of the artwork and all of the publicity materials and bumper stickers and buttons and T-shirts we had just made two months prior, for the new exhibit, were all out of date,” he says with a laugh.

Davis is co-author of the new study in the journal PLOS One, which renames the giant fish the “spike-toothed salmon.”

It says the salmon used the tusk-like spikes for building nests to spawn, and as defence mechanisms against predators and other salmon.

The salmon lived about five million years ago at a time when Earth was transitioning from warmer to relatively cooler conditions, Davis says.

It’s hard to know exactly why the relatives of today’s sockeye went extinct, but Davis says the cooler conditions would have affected the productivity of the Pacific Ocean and the amount of rain feeding rivers that served as their spawning areas.

Another co-author, Brian Sidlauskas, says a fish the size of the spike-toothed salmon must have been targeted by predators such as killer whales or sharks.

“I like to think … it’s almost like a sledgehammer, these salmon swinging their head back and forth in order to fend off things that might want to feast on them,” he says.

Sidlauskas says analysis by the lead author of the paper, Kerin Claeson, found both male and female salmon had the “multi-functional” spike-tooth feature.

“That’s part of our reason for hypothesizing that this tooth is multi-functional … It could easily be for digging out nests,” he says.

“Think about how big the (nest) would have to be for an animal of this size, and then carving it out in what’s probably pretty shallow water; and so having an extra digging tool attached to your head could be really useful.”

Sidlauskas says the giant salmon help researchers understand the boundaries of what’s possible with the evolution of salmon, but they also capture the human imagination and a sense of wonder about what’s possible on Earth.

“I think it helps us value a little more what we do still have, or I hope that it does. That animal is no longer with us, but it is a product of the same biosphere that sustains us.”

This report by The Canadian Press was first published April 24, 2024.

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Nasa's Hubble marks 34th anniversary with stunning view of Little Dumbbell Nebula – The Times of India

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In celebration of its 34th anniversary, Nasa‘s Hubble Space Telescope has once again wowed astronomers and space enthusiasts alike by capturing an extraordinary image of the Little Dumbbell Nebula. This latest image offers a vivid glimpse into the complexities of a planetary nebula, demonstrating Hubble’s enduring capabilities in its extended mission.
The Little Dumbbell Nebula, also known as Messier 76, is one of the faintest objects in the Messier catalog and has intrigued astronomers for its intricate structure and dual-lobed shape. This planetary nebula, located approximately 2,500 light-years away in the constellation Perseus, represents a brief stage in the life cycle of a moderate-sized star like our sun.
Dr. Jennifer Wiseman, a senior scientist at Nasa’s Goddard Space Flight Center, expressed her admiration for the new imagery: “This beautiful nebula is what remains after a star like our own sun has exhausted the bulk of its nuclear fuel and shed its outer layers. The vibrant colors and intricate structures visible in the nebula are a telescope’s way of painting the portrait of the final stages of stellar evolution.”
The Little Dumbbell Nebula, despite its faintness, shines brightly in the detailed images provided by Hubble, allowing scientists to study aspects of the nebula that are rarely visible. The images highlight the dense, glowing gas and complex layers of material expelled from the dying star at the center of the nebula.
According to Dr. Wiseman, “Hubble’s high-resolution capabilities allow us to examine the fine details within the nebula, helping us understand how stars expel their material and the dynamics of this expulsion process. This image is more than just a picture; it’s a deep dive into the life of stars.”
Since its launch on April 24, 1990, Hubble has revolutionized our understanding of the universe, from the dynamics of galaxies to the atmospheres of exoplanets and the distribution of dark matter. Its contributions continue to support and complement data gathered by newer space observatories.
As Hubble continues its journey in space, the scientific community remains enthusiastic about the ongoing contributions it will bring to our understanding of the cosmos. Dr. Wiseman remarked, “Every image from Hubble is a new lesson in our cosmic curriculum.”
These observations not only contribute significantly to our knowledge of the life cycle of stars but also continue to highlight the critical role of Hubble in the exploration and understanding of our universe. As Hubble enters another year in orbit, its legacy of discoveries promises to keep inspiring both the scientific community and the public.

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SpaceX launch marks 300th successful booster landing – Phys.org

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Credit: Unsplash/CC0 Public Domain

SpaceX sent up the 30th launch from the Space Coast for the year on the evening of April 23, a mission that also featured the company’s 300th successful booster recovery.

A Falcon 9 rocket carrying 23 of SpaceX’s Starlink internet satellites blasted off at 6:17 p.m. Eastern time from Cape Canaveral Space Force Station’s Space Launch Complex 40.

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The first-stage booster set a milestone of the 300th time a Falcon 9 or Falcon Heavy booster made a successful recovery landing, and the 270th time SpaceX has reflown a booster.

This particular booster made its ninth trip to space, a resume that includes one human spaceflight, Crew-6. It made its latest recovery landing downrange on the droneship Just Read the Instructions in the Atlantic Ocean.

The company’s first successful booster recovery came in December 2015, and it has not had a failed booster landing since February 2021.

The current record holder for flights flew 11 days ago making its 20th trip off the .

SpaceX has been responsible for all but two of the launches this year from either Kennedy Space Center or Cape Canaveral with United Launch Alliance having launched the other two.

SpaceX could knock out more launches before the end of the month, putting the Space Coast on pace to hit more than 90 by the end of the year, but the rate of launches by SpaceX is also set to pick up for the remainder of the year with some turnaround times at the Cape’s SLC-40 coming in less than three days.

That could amp up frequency so the Space Coast could surpass 100 launches before the end of the year, with the majority coming from SpaceX. It hosted 72 launches in 2023.

More launches from ULA are on tap as well, though, including the May 6 launch atop an Atlas V rocket of the Boeing CST-100 Starliner with a pair of NASA astronauts to the International Space Station.

ULA is also preparing for the second launch ever of its new Vulcan Centaur rocket, which recently received its second Blue Origin BE-4 engine and is just waiting on the payload, Sierra Space’s Dream Chaser spacecraft, to make its way to the Space Coast.

Blue Origin has its own it wants to launch this year as well, with New Glenn making its debut as early as September, according to SLD 45’s range manifest.

2024 Orlando Sentinel. Distributed by Tribune Content Agency, LLC.

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SpaceX launch marks 300th successful booster landing (2024, April 24)
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