Searching for advanced civilizations in other galaxies: 50 possible candidates found?

At first, this article seems like a bit of a downer:
Search for advanced civilizations beyond Earth finds nothing obvious in 100,000 galaxies — ScienceDaily.

After searching 100,000 galaxies for signs of highly advanced life, a team of scientists has found no evidence of advanced civilizations there. The idea behind the research is that, if an entire galaxy had been colonized by an advanced spacefaring civilization, the energy produced by that civilization’s technologies would be detectable in mid-infrared wavelengths.

…”Whether an advanced spacefaring civilization uses the large amounts of energy from its galaxy’s stars to power computers, space flight, communication, or something we can’t yet imagine, fundamental thermodynamics tells us that this energy must be radiated away as heat in the mid-infrared wavelengths,” Wright said. “This same basic physics causes your computer to radiate heat while it is turned on.”

Theoretical physicist Freeman Dyson proposed in the 1960s that advanced alien civilizations beyond Earth could be detected by the telltale evidence of their mid-infrared emissions. It was not until space-based telescopes like the WISE satellite that it became possible to make sensitive measurements of this radiation emitted by objects in space.

However, somewhat contradicting the title of the article and its opening passage, we have this snippet:

Wright reports, “We found about 50 galaxies that have unusually high levels of mid-infrared radiation. Our follow-up studies of those galaxies may reveal if the origin of their radiation results from natural astronomical processes, or if it could indicate the presence of a highly advanced civilization.”

I’m not entirely sure what to make of this passage given the apparent contradiction, but it sounds like we have 50 possible candidate galaxies for advanced civilizations.  (Emphasis on the word “possible” here.)

Based on the information the article provides, it seems obvious that the scientists were looking for Type III civilizations on the Kardashev scale.  A Type I civilization has harnessed all of the energy on its native planet.  (We’re not a Type I civilization yet).  A Type II civilization has harnessed all of the energy of its native star, possibly using concepts like Dyson spheres or swarms.  And a Type III civilization will  have harnessed all of the energy in its galaxy, or, at least for purposes of this study, enough to be noticeable across intergalactic distances.

Of course, we have no real idea how possible a Type III civilization actually is.  It would involve engineering on scales that currently seem hard to imagine.  But given enough time (think hundreds of millions of years), there doesn’t seem to be anything in the laws of physics that prevent it.  We also can’t be sure that some observed astronomical phenomena that we’re chalking up to nature might not turn out to be mega-structures created by extraterrestrial intelligence.

But given the age of the universe, and the fact that there’s no evidence of Earth ever having been colonized in its 4.5 billion year history, it seems likely that if there are advanced civilizations out there, they’re too far away to have reached us yet.  50 out of 100,000 galaxies sounds like about the right number.  The nearest advanced civilization may be several hundred million light years away.

Unless they find natural explanations for the high levels of mid-infrared radiation.  Then the closest advanced civilization might might be billions of light years away, or even outside our visible universe.

The Milky Way May be 50 Percent Bigger Than Thought

Sometimes it’s amazing how much settled science, even something as longstanding as the size of our galaxy, can get called into question: The Milky Way May be 50 Percent Bigger Than Thought : Discovery News.

A ring-like filament of stars wrapping around the Milky Way may actually belong to the galaxy itself, rippling above and below the relatively flat galactic plane. If so, that would expand the size of the known galaxy by 50 percent and raise intriguing questions about what caused the waves of stars.

…Evidence that the so-called Monoceros Ring, located more than 65,000 light-years from the center of the galaxy, actually is part of the Milky Way surprised Newberg, who was on a team that discovered the ring in 2002.

I have to admit that I hadn’t really heard of the Monoceros Ring, or if I had, it hadn’t stuck in my consciousness.  Reading about it now, it appears to be a controversial ring of stars either surrounding our galaxy, or on the outer edges of it.  The controversy involves whether the stars were gravitationally torn from another galaxy that passed by, or are stars from our galaxy separated from us in a wave like configuration that may have been caused by the gravity of another dwarf galaxy passing through.

The debate about whether or not it is part of the Milky Way, in some ways, reminds me of the debate about whether or not Pluto is a planet.  It should be remembered that our galaxy is as big as it is because, over the history of the universe, it has merged with a lots of other galaxies.  Galaxies aren’t static things, but are constantly evolving over billions of years.

When I was a kid, everyone thought that the space between galaxies was basically an empty void, but we now know that it’s thinly filled with stars and gases.  In addition, there are lots of dwarf galaxies in orbit of ours, which it seems we’re more likely to call star clusters as they get closer to the main galaxy’s halo.  The edge of the galaxy is much hazier than it used to be, so exactly where we draw the line between the inside or outside of it seems a much more arbitrary matter than it used to be.

A close pass by a red dwarf star, and a note on interplanetary and interstellar distances

First, in case you haven’t heard: 70,000 Years Ago, Another Star Flew by the Edge of the Solar System | RealClearScience.

According to an international team of astronomers, about 70,000 years ago a red dwarf star — nicknamed “Scholz’s star” for the astronomer who discovered it — passed by our solar system just 0.8 light years distant. In fact, 98% of the 10,000 simulations the team ran projected that the star’s path grazed the outer edges of the Oort Cloud, a region of space filled with icy planetesimals which marks the final boundary of our solar system.

…Scholz’s star is now twenty light years away and won’t be returning anytime soon. However, Dr. Coryn Bailer-Jones of the Max Planck Institute for Astronomy calculates that we may receive another visitor in the distant future. Last December, Baller-Jones reported that the rogue star HIP 85605 may pass as close as .132 light years to the solar system between 240,000 and 470,000 years from now. That’s a close miss on the cosmic scale, but more than far enough that our futuristic ancestors will have little to worry about. The only concern would be that HIP 85605’s foray through the inner Oort Cloud might send a few comets careening in Earth’s direction.

This is interesting and just goes to show that, on a large enough time scale, assuming we don’t drive ourselves extinct, humanity will eventually be able to go to the stars, even if we have to wait for other stars to occasionally come near us.  (Not that we could make such a trip with current technology, but it’s a lot easier than reaching the nearest current star.)

That said, it’s important to keep in mind what “near” means in this context since some news outlets are saying the star passed “within” our solar system, implying to most people that it passed near the planets or something.  As Pomeroy notes, this pass was 0.8 light years away.  While it’s less than a fifth the distance to the current nearest star (Proxima Centauri), that’s still over seven trillion kilometers, over 52,000 times the distance between the Earth and the Sun, or more than 1300 times the distance to Pluto.  Even the star HIP 85605 mentioned above that might some day pass as close as 0.132 light years away will still be more than 200 times the distance of Pluto.

Saying that these near passes are within our solar system is only accurate if your consider the solar system to encompass the theoretical Oort Cloud, thought to be a cloud of icy rocks that extends as far as 2 light years away, or half the distance to the next nearest star.  While some might argue that the phrase is accurate, it’s a far broader meaning of “solar system” than most people are familiar with.

It also illustrates that, as large as the solar system is, and it is incomprehensibly large by any human scales, it’s essentially the outer layers of the Sun when seen from interstellar distances.

Space is big. Really big. You just won’t believe how vastly, hugely, mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist’s, but that’s just peanuts to space.

Douglas Adams, The Hitchhiker’s Guide to the Galaxy


Complex life in the universe may be much rarer than previously thought

At least, according to a couple of astrophysicists: Complex life may be possible in only 10% of all galaxies | Science/AAAS | News.

The universe may be a lonelier place than previously thought. Of the estimated 100 billion galaxies in the observable universe, only one in 10 can support complex life like that on Earth, a pair of astrophysicists argues. Everywhere else, stellar explosions known as gamma ray bursts would regularly wipe out any life forms more elaborate than microbes. The detonations also kept the universe lifeless for billions of years after the big bang, the researchers say.

…The sheer density of stars in the middle of the galaxy ensures that planets within about 6500 light-years of the galactic center have a greater than 95% chance of having suffered a lethal gamma ray blast in the last billion years, they find. Generally, they conclude, life is possible only in the outer regions of large galaxies. (Our own solar system is about 27,000 light-years from the center.)

Things are even bleaker in other galaxies, the researchers report. Compared with the Milky Way, most galaxies are small and low in metallicity. As a result, 90% of them should have too many long gamma ray bursts to sustain life, they argue. What’s more, for about 5 billion years after the big bang, all galaxies were like that, so long gamma ray bursts would have made life impossible anywhere.

This is sobering when considering how much life might be in the visible universe.  It doesn’t really change the possibility of life on the exoplanets in our neighborhood of the galaxy.  I still tend to think we’ll find evidence of life in the light spectrum reflected off one of those exoplanets within a few decades.  And there’s this caveat in the article:

But are 90% of the galaxies barren? That may be going too far, Thomas says. The radiation exposures Piran and Jimenez talk about would do great damage, but they likely wouldn’t snuff out every microbe, he contends. “Completely wiping out life?” he says. “Maybe not.”  But Piran says the real issue is the existence of life with the potential for intelligence. “It’s almost certain that bacteria and lower forms of life could survive such an event,” he acknowledges. “But [for more complex life] it would be like hitting a reset button. You’d have to start over from scratch.

Most of my regular readers will know that I already tend to think that microbial life is the most prevalent in the universe, that complex life is rare, and that, due to the Fermi Paradox, intelligent life is profoundly rare.  Having biospheres periodically purged every few hundred million years throughout most of the universe probably just makes complex and intelligent life orders of magnitude rarer yet.

I usually say that our closest neighboring civilization may be in another galaxy.  If these findings stand, it might be more likely that they’re hundreds of millions, if not billions, of light years away.  Of course, it’s also possible that civilizations arise more often than I’m thinking, but that virtually all of them get wiped out from a gamma ray burst before they get a chance to spread.

Either way, the chances of us ever meeting any of them appear to be increasingly unlikely.

The article finishes with some possible advice for SETI:

The analysis could have practical implications for the search for life on other planets, Piran says. For decades, scientists with the SETI Institute in Mountain View, California, have used radio telescopes to search for signals from intelligent life on planets around distant stars. But SETI researchers are looking mostly toward the center of the Milky Way, where the stars are more abundant, Piran says. That’s precisely where gamma ray bursts may make intelligent life impossible, he says: “We are saying maybe you should look in the exact opposite direction.”

Half the stars in the universe may exist outside of galaxies

Every so often you get a reminder of how little we know about the universe: Rogue stars outside galaxies may be everywhere | Science/AAAS | News.

You’ve heard of rogue planets, floating through the universe untethered to any solar system. Now meet rogue stars, which drift through space with no galaxy to call home. A new study has come to the startling conclusion that as many as half of all stars in the universe may be rogue, having been ejected from their birthplaces by galaxy collisions or mergers.

The article goes on to discuss that this is just a possibility at this point.  Not everyone is convinced.

“We’ll have to confirm, but they are hard to accommodate with the star model,” he says. Also, he points out, if there is a huge population of stars outside galaxies, we should see a noticeable number of supernovas occurring out in the middle of nowhere as those rogues stars die. “There are ways to test in the near term. It’ll be an enthusiastically pursued question,” Moseley says.

But if this does turn out to be true, what a revision to our view of the universe!  All this time we’ve been thinking that the space between galaxies was this vast emptiness with only the occasional gas or dark matter particle, but now it may be filled (relatively speaking) with stars.  (Yeah, I know “filled” is probably not the right word since even within galaxies there is an unimaginably vast emptiness between stars.  But intergalactic emptiness would still seem a lot less empty than we had previously understood.)

So, in recent years, we’ve learned that there are billions of rogue planets between the stars, and now we may be headed toward learning that half of all stars are between galaxies.  If nothing else, this should keep us humble about what we think we know about the universe.

Video on Laniakea supercluster

I reported on this yesterday, but Nature has put out a video with more information that is well worth checking out.  As a bonus, it demonstrates how to pronounce Laniakea!

h/t Matthew Cobb at Why Evolution Is True


Your cosmic address: The edge of the Laniakea supercluster

This is pretty cool: New Map Locates Milky Way in Neighborhood of 100,000 Galaxies.

A new map of the Milky Way’s cosmic neighborhood shows where our galaxy lives in relation to thousands of others nearby, with scientists giving the newly discovered “supercluster” of galaxies a name: Laniakea, which means “immeasurable heaven” in Hawaiian.

Throughout the universe, galaxies tend to clump together in massive structures that astronomers call superclusters. According to the new map, Earth’s galaxy lives near the edge of the Laniakea supercluster, which measures 500 million light-years in diameter and includes roughly 100,000 galaxies.

The region is just a small slice of the visible universe, which spans more than 90 billion light-years.

As someone who spends his share of time reading about astronomy, I’ve often wondered why most astronomical literature rarely identified the galactic supercluster that we live in, despite mentioning others like Coma or Perseus-Pisces.  I’ve occasionally heard our home supercluster called the Virgo supercluster, presumably after the Virgo cluster which is in our cosmic neighborhood.  But it turns out that our local supercluster wasn’t well mapped out and the “Virgo” name was unofficial.

Now it is official.  We live in the Laniakea supercluster.  Just to review our cosmic address:

  1. Earth
  2. Solar System
  3. Orion-Cygnus Arm of the Milky Way
  4. Milky Way galaxy
  5. Local Group (of galaxies)
  6. Laniakea Supercluster
  7. Universe

After that we get into speculative concepts like bubble multiverses.

You say multiverse, I say galaxies

English: Great Andromeda Nebula. Public domain...
(Photo credit: Wikipedia)

Corey Powell has an interesting post up on what he calls the Four Great Eras of Exploration.  The first era was Galileo’s discovery of the vastness of the universe, the second that stars were composed of chemical elements, and the third was Hubble’s discovery of other galaxies.  The fourth, and main topic of his post, is the current age of discovery of exoplanets.

But for this post, I’m focusing on the third:

Overnight, the Andromeda Nebula became the Andromeda Galaxy, and our home galaxy became just one of a multitude. A scant 6 years later, Hubble measured the motions of those other galaxies and discovered that they were systematically moving away from us, with their speed directly proportional to their distance. This was the discovery of the expanding universe, which led to the idea of the Big Bang, galaxy evolution, dark energy, and all the other wild concepts of modern cosmology.

I still find it mind-boggling that less than a century ago nobody even knew whether other galaxies existed. The pace of astronomical discovery is truly shocking when you step back and look at it.

I very much agree with that last paragraph.  Less than a century ago, we thought our galaxy was all that was, the entire universe.  Reading this post reminded me of an old archaic term for galaxies: ‘island universes’, which I recall seeing in very old science fiction stories.  The term didn’t stick because ‘universe’ was then understood to mean all of reality.

Thinking about our multiverse discussions, and Tegmark’s levels of multiverse, it occurs to me that galaxies could have been considered other universes at one time, and the space they’re all in, the multiverse.  This is a counter-factual of course, since that’s not where the terminology went.

But it makes me wonder what might happen if we ever actually did discover other universes as described in one or more of the multiverse theories.  Would we end up calling them universes, or something else like bubble, region, brane, or whatever ended up being descriptive?  Maybe the term ‘universe’ might continue to encompass all of reality.

What if our currently observable universe was part of a large structure that was just one of several such structures separated from each other by vast voids.  Would those other remote structures count as other universes, or just new regions of the current one?  At what point is another aspect of reality another universe instead of just a previously unknown aspect of the universe?

Depending how we spliced it, the word ‘universe’ might become like ‘world’, where it would figuratively be used to refer to all of reality, but technically mean a distinct subset of it, similar to how ‘world’ now effectively means ‘planet’.

This line of thought (admittedly largely semantic) reminds me of something cultural anthropologists are always warning us about, that much of how we perceive reality is essentially convention.  Conventions which are often ultimately the result of historical accidents.

The faster interstellar travel is, the further away intelligent aliens are

Ethan Siegel has an excellent post up exploring the possibility of extraterrestrial civilizations.

With hundreds of billions of stars (visible, above, in infrared wavelengths) in our galaxy alone, and literally trillions of planets around them, we have many, many chances for life to have evolved similarly to how it did here on Earth. With at least 200 billion galaxies in the Universe, it seems unfathomable to us that we would be alone as the only self-aware, intelligent, sentient lifeforms in the Universe.

And yet, the titular question of this article — where is everybody — is one of the most famous puzzles in modern science: Fermi’s Paradox. If the Universe is so conducive to life, and if there are so many opportunities for it within our galaxy alone, why isn’t there any evidence of extraterrestrial life?

via Throwback Thursday: Where is Everybody? — Starts With A Bang! — Medium.

Ethan’s piece is excellent and I highly recommend reading it.  But he only obliquely refers to a factor that I consider important in this question, which I’ve written about before: the degree to which interstellar travel is possible.

It seems to me that everything Siegel lays out is correct, if interstellar travel is effectively impossible.  I say “effectively” because we know it’s possible in the sense of Voyager leaving the solar system and passing by other stars tens of thousands of years from now.  But effective means getting there in some sort of usable time frame, and with technology that is able to function when it arrives.

For that to be conceivable, it seems like the probe needs to get there within a few centuries at most, which implies achieving speeds of at least 1% of the speed of light.  Is that possible?  I don’t think anyone can say for sure, but it seems very conceivable to me that it is using foreseeable technologies.

If it is possible, then it would only require self replicating probes around 100 million years to colonize the entire galaxy.  The galaxy has been around for 13 billion years.  We’ve haven’t been contacted by any of these probes, which implies that it is unlikely that there are any other advanced civilizations in our galaxy, putting the closest civilization possibly millions of light years away.

I’m admittedly ignoring the possibility of “prime directives” and such, mainly because it’s hard to imagine such a directive holding across multiple civilizations and billions of years.

If faster travel is possible, then the distance to the next civilization is further away.  If some form of faster than light travel is possible, the next civilization may be outside of the visible universe.  For a common science fiction trope to be reality, that of alien empires that haven’t noticed us yet, they’d most likely have to operate across distances of billions of light years.

Why is the solar system flat?

Machines Like Us and others linked to this cool video explaining why the solar system is flat.

I’m not entirely sure the four dimensional stuff was necessary, although it was interesting.  One thing to realize though, is that while the solar system is flat, it’s not flat in the same orientation as other solar systems, or to the galaxy as a whole.

The plane of the solar system (the plane of the ecliptic0, is about 23o different than the Earth’s rotational plane (the celestial equator).  Which is why we have seasons.

And the plane of the solar system is inclined about 60o relative to the plane of the Milky Way galaxy.  Don’t worry, other solar systems are also at varied cockeyed angles to the galaxy.

So, although spinning systems like the solar system and the galaxy are flat, they’re not flat in the same plane.  Space is three dimensional.  Something I often wish science fiction movie makers would learn.