Do Advanced Civilizations Know We're Here?

Antennas of the Very Large Array against the Milky Way. Credit: NRAO/AUI/NSF/Jeff Hellerman

Adrift in a great sea of stars, we must surely not be alone.

It’s hard not to look at the night sky and think about the possibility of other civilizations out there. From the philosophical speculations of Giordano Bruno to the statistical estimations of Frank Drake, the more we’ve learned about the universe, the more likely alien life seems to be. And yet, in our search for this life, we have heard nothing but silence.

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What Does 60 Years of Silence Tell Us About the Search for Extraterrestrials?

The Allen Telescope Array searches for alien technosignals. Credit: Seth Shostak, SETI Institute

Aliens are big in the news recently, fueled by congressional hearings about Unidentified Anomalous Phenomena (UAPs), formally known as UFOs. But while the idea of aliens visiting Earth may be exciting, the better bet is still the idea that aliens might exist on distant worlds. We already know potentially habitable planets are common and intelligent life has arisen on at least one world, so why not many? But after 60 years of searching for evidence of extraterrestrials “out there,” we’ve found nothing. So what does that tell us?

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SETI Researchers Are Simulating Alien Contact — and You Can Help

Allen Telescope Array
Radio telescopes monitor the sky at the Allen Telescope Array in California. (SETI Institute Photo)

Is it a multimedia art project? Or a rehearsal for alien contact? Let’s call it both: Researchers specializing in the search for extraterrestrial intelligence, or SETI, are working with a media artist to stage the receipt of an interstellar message — and a global effort to decode the message.

The project, titled “A Sign in Space,” is orchestrated by media artist Daniela de Paulis in collaboration with the SETI Institute, the European Space Agency, the Green Bank Observatory and the Italian National Institute for Astrophysics (also known as INAF).

The metaphorical curtain rises on May 24, when ESA’s ExoMars Trace Gas Orbiter transmits an encoded radio message from Martian orbit to Earth at 19:00 UTC / noon PDT.

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Aliens Could Map Earth From its Mobile Phone Towers

A mobile cell tower on a clear day. Credit: Ervins Strauhmanis, via Flickr

Mobile phones are so ubiquitous that we typically don’t think about how they work. They just do, much to our benefit, and sometimes annoyance. But the key to their function is a vast array of radio transmission towers. These cell towers span a large percentage of Earth’s land surface, particularly in heavily populated areas, and they transmit microwave signals all the time. With all those cell towers emitting all those radio signals, a fun question to ask is whether those signals could be detected by an alien civilization.

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Maybe We Don’t See Aliens Because Nobody Wants to Come Here

Artist impression of an alien civilization. Image credit: CfA

The Fermi Paradox won’t go away. It’s one of our most compelling thought experiments, and generations of scientists keep wrestling with it. The paradox pits high estimates for the number of civilizations in the galaxy against the fact that we don’t see any of those civs. It says that if rapidly expanding civilizations exist in the Milky Way, one should have arrived here in our Solar System. The fact that none have implies that none exist.

Many thinkers and scientists have addressed the Fermi Paradox and tried to come up with a reason why we don’t see any evidence of an expanding technological civilization. Life may be extraordinarily rare, and the obstacles to interstellar travel may be too challenging. It could be that simple.

But a new paper has a new answer: maybe our Solar System doesn’t offer what long-lived, rapidly expanding civilizations desire: the correct type of star.

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We Could Detect Extraterrestrial Satellite Megaconstellations Within a few Hundred Light-Years

A map of space debris orbiting Earth. Credit: European Space Agency

Starlink is one of the most ambitious space missions we’ve ever undertaken. The current plan is to put 12,000 communication satellites in low-Earth orbit, with the possibility of another 30,000 later. Just getting them into orbit is a huge engineering challenge, and with so many chunks of metal in orbit, some folks worry it could lead to a cascade of collisions that makes it impossible for satellites to survive. But suppose we solve these problems and Starlink is successful. What’s the next step? What if we take it further, creating a mega-constellation of satellites and space stations? What if an alien civilization has already created such a mega-constellation around their world? Could we see it from Earth?

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The First Civilization We Contact Will Have Been Around Much Longer Than Humanity

Recently at UT, author Matt Williams has been writing a series called “Beyond Fermi’s Paradox”, which takes a look at possible resolutions to one of the most famous questions in science: “Where is everybody?”  As Matt discusses, there are multiple hypothetical solutions, but there may eventually come a day when we can definitively answer it.

Consideration of that day opens up a whole host of new questions, not the least of which is what will an intelligent civilization we find be like?  Carl Sagan popularized the notion that it is very unlikely that any extraterrestrial civilization would be equivalent to ours in terms of technological progress.  What he did not address was the relative age of the civilization and what that might mean in terms of their interest in communicating with us.  Now a team of astronomers have come up with an answer to that question using one of the most underappreciated mathematical tools: statistics. Their model provides a simple answer: any intelligent civilization is likely older than us, and potentially much older.

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We use the Transit Method to Find other Planets. Which Extraterrestrial Civilizations Could use the Transit Method to Find Earth?

The three planets discovered in the L98-59 system by NASA’s Transiting Exoplanet Survey Satellite (TESS) are compared to Mars and Earth in order of increasing size in this illustration. Credit: NASA’s Goddard Space Flight Center

We have discovered more than 4,000 planets orbiting distant stars. They are a diverse group, from hot Jupiters that orbit red dwarf stars in a few days to rocky Earth-like worlds that orbit Sun-like stars. With spacecraft such as Gaia and TESS, that number will rise quickly, perhaps someday leading to the discovery of a world where intelligent life might thrive. But if we can discover alien worlds, life on other planets could find us. Not every nearby star would have a good view of our world, but some of them would. New work in the Monthly Notices of the Royal Astronomical Society tries to determine which ones.

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Extraterrestrial Hunters Figure Out a Way to Expand Their Search for Signals by a Factor of 200

Credit: Breakthrough Listen/Univ. of Machester/Daniëlle Futselaar

In 2015, Russian-American billionaire Yuri Milner established Breakthrough Initiatives, a non-profit organization dedicated to advancing space exploration. Central to this effort is Breakthrough Listen, a ten-year international research program dedicated to the Search for Extraterrestrial Intelligence (SETI) and the largest and most sophisticated effort to find intelligent life beyond Earth to date.

In the past five years, the project has made two major data releases (in the June of 2019 and February of 2020) and announced that it found no signs of alien transmissions from the 1,327 nearest star systems. But thanks to an analytical breakthrough recently proposed by researchers from the University of Manchester, it looks as though Breakthrough Listen’s search efforts could be expanded by a factor of more than 200!

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Calculate the Number of Alien Civilizations in the Milky Way for Yourself.

Planets everywhere. So where are all the aliens? Credit: ESO/M. Kornmesser

In recent years, the explosive nature of exoplanet discovery (over 4,164 confirmed so far!) has led to renewed interest in the timeless question: “are we alone in the Universe?” Or, as famed Italian physicist Enrico Fermi put it, “Where is everybody?” With so many planets to choose from and the rate at which our instruments and methods are improving, the search for life beyond Earth is really kicking into high gear.

At the same time, these discoveries have inspired a plethora of new studies regarding the ongoing Search for Extraterrestrial Intelligence (SETI). This includes the Alien Civilization Calculator, which is the brainchild of physicists Steven Woodling and Dominick Czernia. Inspired by recent attempts to address the statistical likelihood of advanced life in our galaxy, they offer a mathematical tool that can crunch the numbers for you!

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