Galactic Colonization

  • Published on: 24 March 2020
  • Have you ever wondered if there’s a Galactic Empire out there? How long would it take a space faring civilization to colonize the entire galaxy? Remarkably even traveling at sub-light speeds this should be possible within a fraction of our galaxy’s lifetime. Which raises the question - why hasn’t this happened yet? Today we dive into the repercussions of “Fact A” - the simple observation that Earth has not been colonized by an alien civilization. I sit down with Prof. Jason Wright who has recently co-authored a new paper that provides the most sophisticated treatment to date of this problem, and what it means for our place in the Universe.

    Interview with Prof. Jason Wright. Presented & Written by Prof. David Kipping.

    You can now support our research program and the Cool Worlds Lab at Columbia University:

    ► Carroll-Nellenback, J., Frank, A., Wright, J. & Scharf, C., 2019, "The Fermi Paradox and the Aurora Effect: Exo-civilization Settlement, Expansion, and Steady States", ApJ, 158, 117:
    ► Hart, M., 1975, "Explanation for the Absence of Extraterrestrials on Earth", Quart. J. RAS, 16, 128:

    Video materials and graphics used:
    ► Opening Galaxy shot by Bridge Head Productions:
    ► Abiogenesis animation by TheOriginOfLife
    ► Exoplanet animations ESO/M. Kornmesser: &
    ► Galaxy zoom by Emilio Music Productions:
    ► Microbiology footage from Nokia Small World in Motion Competitions:,,,
    ► Sunset video by kagnet:
    ► Cave painting from Cave Art 101, National Geographic:
    ► Rocket animation Егор Румянцев:
    ► SpaceX Mars animation by SpaceX:
    ► Galactic colonization animation by ESA Advanced Concepts Team: h
    ► Galaxy spinning animation by Huy Trường Nguyễn:
    ► Journey to Alpha Cen by ESO./L. Calçada/Nick Risinger (
    ► Exoplanet K2-18b by ESA/Hubble/M. Kornmesser:
    ► Galaxy fly-in by Batsaikhan Ariun-Erdene:
    ► Timelapse of AKSAP telescope by Alex Cherney:
    ► Closing Milky Way shot by Alexandra Angelich (NRAO/AUI/NSF):

    Movies/TV scenes used:
    ► Contact (1997)/Warnes Bros.
    ► Alien: Covenant (2017)/20th Century Fox
    ► Interstellar (2014)/Paramount
    ► Star Trek/Paramount
    ► Terminator 3: Rise of the Machine (2003)/Warner Bros.
    ► Alien (1979)/Warner Bros.

    Music used, in chronological order:
    ► "Waking Up" by Atlas, licensed through
    ► Cylinder Five ( by Chris Zabriskie (; licensed under a Creative Commons Attribution license (
    ► The Sun is Scheduled to Come Out Tomorrow ( by Chris Zabriskie (; licensed under a Creative Commons Attribution license (
    ► Cylinder Four ( by Chris Zabriskie (; licensed under a Creative Commons Attribution license (
    ► Music from Neptune Flux, "The Oceans Continue to Rise" by Chris Zabriskie (; licensed under a Creative Commons Attribution license (
    ► "Selha" by Stephen Keech, licensed through

    And also...
    ► Columbia University Department of Astronomy:
    ► Cool Worlds Lab website:

    Latest Cool Worlds Videos ►
    Cool Worlds Research ►
    Cool Worlds Long Form Videos ►
    Guest Videos ►
    Q&A Videos ►
    Tabby's Star ►
    Science of TV/Film ►

    SUBSCRIBE to the channel


    #GalacticColonization #FermiParadox #FactA
  • Runtime : 23:35
  • Astronomy Astrophysics Exoplanets Cool Worlds Kipping


  • Kate Sun
    Kate Sun   1 weeks ago

    Wow you are both smart and cute!

  • Bronk Master
    Bronk Master   1 weeks ago

    Probably it Is just sad in a way that civs try hard but just do not succeed enough. Due to lethal interaction of them with the universe itself.Gamma bursts, asteroids, Supernovae, wrong choices (direction to fly, planet properties, hosting star behavior (outbreaks, cyclic changes)).Hope it Is a different story, but hey: What can Go wrong, will go wrong.

  • Caleb Smith
    Caleb Smith   2 weeks ago

    One possibility that I don’t hear discussed often: what if the universe is teeming with life, but this life rarely becomes intelligent enough to form civilization? I mean, it took 4 billion years to go from bacteria to people. What if most planets can’t sustain life that long? And even if they do, there’s no guarantee that 4 billion years of evolution will produce intelligence

  • Chris Collins
    Chris Collins   2 weeks ago

    Who’s to say any intelligent life colonizing the galaxy hasn’t already been here millions of years ago and they just buggered off?

  • Mike Jackson
    Mike Jackson   2 weeks ago

    There exists a galaxy far, far away that is full of life. I've seen it on the telly.

  • Mostly Peaceful
    Mostly Peaceful   2 weeks ago

    if they were an "ambitious settlement" why would they only send a ship every 100,000 years? or even 10,000 years? and how is 10,000 years "very frequent" i can't even imagine what an expansionist civ would be doing for 10,000 years between launches, would they all just be lounging around exhausted. "you can't ask us to work on another ship, some of our great great great great great great great great great great great great great granadfathers worked on the last one and we're still tired"sometimes people are super intelligent but have no common sense.

  • ChessMasterNate
    ChessMasterNate   2 weeks ago

    The analysis is not as open-minded or rational as presented. The, what should be obvious, flaw is that you assume that it is hard to survive and thrive places that are different than their home planet, or that planets are even necessary near stars for mobile life. But in all cases of interstellar travel, they already survived the most extreme case when traveling between the stars in the first place. True, they are not likely growing and flourishing while traveling, but they only need mater and energy at the destination to do so, and low levels of the kinds of radiation deadly to them, that they can't easily block. They almost certainly near fully colonized their own solar system before striking out to go to another. They likely were in the tens of trillions of individuals or more in that home solar system (unless they are very large organisms), with only a small fraction living on the home planet. And I am not assuming terraforming. I expect they would feel no need. Everything sufficient for an excellent life can be manufactured in space or on asteroids, moons, and hundreds of other locations. Only after much of the non-planetary mater has been digested into habitats and support systems would they leave. Now, if the mater at a star has no residuals from past supernovae orbiting it, then that mater may be insufficient...but I don't think that is common, though it might have been, billions of years ago, narrowing the time that colonization has been possible.It might even be a short time that there are planets at a colonized solar system. It all may be quickly disassembled to make habitats. I think the biggest argument for intelligent technological life being exceedingly rare is not that we haven't seen it, it is that we haven't seen their A.I.s. I would think that they would send A.I.s ahead to make solar systems into habitats...and they would not stop until the whole Galaxy was converted...whether or not the species for whom they built still remained.Of course, there are uglier reasons there may be limited life, like intentional sterilization.I think we are far from knowing. Our means of detection are just too weak.And stellar phenomena may naturally periodically sterilize large areas.

  • Haripazha Aezakmi
    Haripazha Aezakmi   2 weeks ago

    Does the ufo can be a sign that there is something living outside earth? What about those egyptian wall painting that foretell some outsider species?

  • Simon
    Simon   3 weeks ago

    Maybe earth isnt even habitable to these aliens

  • Kyle Spencer
    Kyle Spencer   3 weeks ago

    Love this professor. When he talks and emphasizes his sentences, it actually keeps you awake and focused to keep learning clearly.

  • IcantSignIn
    IcantSignIn   3 weeks ago

    And we could also be the oldest civilization and WE'VE only had radio for a short time.

  • Alex Ohana
    Alex Ohana   3 weeks ago

    I think chances are we’re not alone. Two people who spent their whole lives isolated on a island might think smoke signals are the most sophisticated form of long distance communication. They may also believe no one else exists. Little do they know there are billions of other people who use radio frequency signals to communicate. We might be on that island right now

  • Pete Davis
    Pete Davis   3 weeks ago

    Humans always wanting to go plant a flag. We're not even smart enough to keep our own planet habitable and we have the arrogance to think we can go out and create/find habitable planets... We don't deserve any other planets. We have an amazing one right here that we're decimating. THEY aren't going to let us and THEY shouldn't let us.

  • FEEL Cool
    FEEL Cool   3 weeks ago

    I don't look and expect to find life. I don't look and see a lonely serene galaxy.I look and see virtually infinite possibility for us to explore, settle, and spread life throughout the galaxy.As a side note. Having viable planets for settlement needn't be a prerequisite for the settlement of a star system, but only the emergence if a native civilitation. In fact, it may be more advantageous to utilize resources outside of gravity wells to construct colonies in 'free space'... as this could be done one a much larger scale, much quicker, and in many more star systems.

  • Nathan Swigg
    Nathan Swigg   3 weeks ago

    how do we know Earth isnt an alien colony? why can't we be the aliens?

  • Blue Rose
    Blue Rose   3 weeks ago

    Maybe we are the ones that will colonize and conquer. It’s in our genes.

  • Nick Mack
    Nick Mack   3 weeks ago

    With 100's of billions of stars in the galaxy alone, the chances for life not to exist, especially intelligent life forms is very slim.. there's just so many stars and almost endless amounts of planets for there not to be at least microorganisms.. intelligent life forms are probably fewer in-between though. The planets for intelligent life has to be absolutely just right for the.

  • Shanti Shanti
    Shanti Shanti   3 weeks ago

    It is pretty arrogant to think that an advanced civilization wants to have anything to do with us. It’s also pretty arrogant to think that we are advanced enough to be able to detect them.

  • Blitz Motor Scooters
    Blitz Motor Scooters   3 weeks ago

    Alot of things he expressed, Ive considered for years but never heard anyone else express. Reminds me of SFIA Channel. Good stuff.

  • b m
    b m   3 weeks ago

    He called him a very "productive" and "accomplished" exo-planet hunter, because it wouldn't have been accurate to call him "successful". 😜

  • Pete
    Pete   3 weeks ago

    Your blathering on at the start was an instant HARD PASS.

  • OmgLolWtfxD x
    OmgLolWtfxD x   3 weeks ago

    fermi’s paradox assumes hyper-intelligent life is in abundance in this universe, so much so, that we should have encountered another life form by now. i don’t believe that to be the case at all. life is elsewhere in the universe, our existence (all animals on earth) makes that a certainty. the question is, is there hyper-intelligent life elsewhere too? just look at earth; out of the ~2 million species of animals on this planet, only one is intelligent enough to create art, school systems, hospitals, government, medicine, technology, and much more. could be our level of intelligence was a happy accident, or it’s just extremely rare.

  • Jack Strawb
    Jack Strawb   4 weeks ago

    For the love of god, stop speaking in sentence fragments.

  • Paul S
    Paul S   4 weeks ago

    Still too many assumptions by your “expert “

  • Val X
    Val X   1 months ago

    Honestly I have a hunch the solution to the Fermi paradox is that the universe just doesn't need that many observers

  • Kelly Parks
    Kelly Parks   1 months ago

    So many assumptions. For example is "settlements" the right word? I think an expanding civilization like that might settle some systems but merely send advanced probes to the uninteresting-to-settlers ones. And your assumption about the lifespan of civilizations irks me. Imagine a nuclear WWIII in the 1980's. Cities destroyed, hundreds of millions dead in the US and the Soviet Union (and China -- the Soviets would have nuked them hard to keep them from taking advantage of the situation and snatching up resource rich Siberia). Civilization destroyed? Not really, since all the nations of Central America (and Mexico), South America, and Africa, as well as many island nations, remain intact. They'd be hit hard by the climatic effects and the fallout but their cities still stand. Some might collapse in the following year but not all. Civilization has taken a hit but certainly not been destroyed. It takes more than a nuclear war to do that.

  • Roli Rivelino
    Roli Rivelino   1 months ago

    The biggest problem I have with Fermi's Paradox, and indeed this (extremely good) video, is the massive assumption that planetary based colonisation is, and always will be the best way to propagate a species throughout the galaxy.First of all, we haven't even colonised another planet yet. We haven't even begun to dream about the technology that would make that truly possible, and who knows? When we get there we might find that there are insurmountable problems that come with living on another planet. For instance, every mammal on Earth including us, has evolved to grow a foetus to full term and give birth in more or less 1G. Ergo if we were on Mars at 0.3G any foetuses would develop with horrible abnormalities.Perhaps its not such a big jump to think that if you have the technology to jump between stars, then why not simply live on that tech and use it to explore? Thus Fermi's Paradox is solved; Where is everyone? A: Floating around looking for someone to talk to.

  • florin2tube
    florin2tube   1 months ago

    Without any scientific approach, I believe that we are not alone. However, this doesn't means that it's mandatory to meet other civilizations. Thank you for this great video!

  • Raphael de Moraes Fontella

    "In the day humans achieve the capacity to colonize other stars, it will be the day that not only humans won. It will be the day that every single life on Earth, from the smallest microbe to the great blue whales on the oceans, and even the Earth itself with all her loving fields and internal fiery fury, also won. For we are extensions of it. We go, they come with us."-Me.

  • Freedom First
    Freedom First   1 months ago

    Technology requires Oxygen, in order to have fire, in order for metallurgy to take place. We must focus on finding planets with similar levels of oxygen as earth.

  • Frank Leblanc
    Frank Leblanc   1 months ago

    I don't buy the sheer numbers argument that just because there are billions of planets around billions of stars in our galaxy there must be life and civilizations out there.I disagree because there are a thousand factors missing from the Drake Equation, all of them crucial to arriving at civilization.The more exoplanets we discover, the more we realize that solar systems like ours are rare. Our number of planets is high and their arrangement uncommon. And that's just two factors.There are many more, such as the giant impact hypothesis and the grand tack hypothesis, and snowball Earth, all of which were essential to the continued evolution of life on Earth, as well as the several bottlenecks caused by repeated mass extinctions.But the ultimate monkey wrench in the Drake Equation is the Cambrian Explosion. The more we study it, the more we realize how unlikely it was to happen at all, even on a planet condusive to life with a long lasting stable hospitable environment persisting for cosmic eons, it still took billions of years for it to happen. And we still don't fully understand why it happened, or how.If it was triggered by a supernova at exactly the right distance to provide presicely the right dose of radiation to provoke widespread genetic mutation without doing too much damage then this factor seems the least likely to repeat itself and has probably happened only once in the history of our galaxy--to our planet, about 630 million years ago, three billion years after life started here.You can pretty much forget about civilizations emerging early in the Milky Way's history for the simple fact that heavy elements, essential to rocky planets and therefore to life itself, were less common in the early universe. The molecules from which life is made are produced inside the cores of dying stars and it takes billions of years for those stars to live and die and propagate their elements through the universe. So the early universe was still made almost entirely from hydrogen and helium.We must also consider how young the universe is. The age of our solar system spans one third the age of the universe itself and the life cycle of our sun will be ten or twelve billion years. So in the 13.7 billion year history of this young universe how many generations of sun-like stars lived and died before our sun was born five billion years ago? One?We must consider the very likely possibility that we are the first civilization to emerge in our galaxy and possibly even among the first to emerge in the whole universe.I can be persuaded into believing that microbial life may be common out there but complex life, animal life, tool-making life, fire-taming life that discovers art and science and eventually builds space ships?We're most likely the only one so far and even if there are others out there they're probably so far away that we'll never meet which means we might as well be alone. And remember, thanks to the expansion, most of the universe is already lost to us forever. If any civilizations exist beyond our observable bubble we will never know about them, no matter now long we survive and no matter how fast or how far we travel.And anyway, biological life is far too fragile and short lived to survive between the stars for long which means even if other civilizations have ever existed at any point in the past we are far more likely to encounter the AIs they left behind than we are to encounter the biological civilizations that gave birth to them.

  • Raphael Calado
    Raphael Calado   1 months ago

    I really think that there is no paradox at all. When one comes to think , humanity took 200 thousand years to settle down and build civilization, and in 200 years we are already destroying our planet, while the interstellar voyage still is far away of our grasp.To believe that most societies would last long enough to reach interstellar voyage capacity and that they could find perfect habitable worlds is quite some stretch.By our example alone it seems more reasonable to believe that most societies will not only find insurmountable challenges as the survival capabilities out there probably isn’t that high even in the planet they evolved to live in, but probably it is very hard to settle and live in other planets that are not quite fit for their kind of life.Also I can’t stress hard enough how our history demonstrate the difficulties of interstellar capabilities in a nutshell, because in less than a couple centuries of industrial advancement we already are impairing our planet life capacity, while not even near of achieving interstellar travel capacity. This situation in itself is very telling, because besides the circle of extinction we expect to happen in about every 100 million years, our species kinda add to that factor a risk of extinction not dependent of natural causes like vulcanism or asteroids, but the simple risk of self destructive technology being far easier to achieve than interstellar travel.Our society shows us that is far easier to destroy our forests, to pollute our waters, than to land on the moon.To me the real paradox comes in the fact that a society based on the technological advancement like ours apparently tend to obey to the market logic of do something if it is profitable in the immediate future and not to do things in a long run perspective. It is telling that the Nasa budget is a fraction of the budget of the US army, we as a society value too much our petty desire to get and keep being rich, while we don’t value the sustainability of doing so.On the other hand, is hard to imagine a sustainable society, capable to not only advance our interstellar capacity but to manage to be sustainable in a economical and technological fashion, without our current progressive logic that is very dependent of our economic ideology.It seems to me that unless a society can grow to be a intellectual utopian society first and then a technological one after, its destiny is to be a dystopian self destructive society like ours, based on exploration of the world and of ourselves in the benefit of a couple billionaires.Any civilization that values life as little as ours is destined to fail, and honestly it is a good think in the grand scheme of things.

  • Gary Scanlon
    Gary Scanlon   1 months ago

    If we scale the trillions upon trillions of years this universe is likely to be around, down to one year, then we've appeared in the first millisecond of it's existence, leaving the whole year for life to pop up all over the universe. Looking at it that way, it's not hard to imagine we are strong contenders for being the first.

  • Smurves
    Smurves   1 months ago

    We are aiming to find life as we know itBut maybe life on other planets is so different that we would not even recognise it as "life"Maybe they live on planets that we would assume are uninhabitable

  • You wish
    You wish   1 months ago

    Unfortunately I've seen what I can only describe as a UFO. A cloud shaped like a bread roll with the bottom being arc ( like a ice cream scooper remove the bottom of the cloud). An object that flew out of this cloud that started from dead center and through the arc of one side of the cloud that left a trail.

  • koloss
    koloss   1 months ago

    Once again a brilliant content! But I want to point out something else as well. We make an assumption that other civilizations if they exist would want to colonise nearby stars or planets. We humans tend to think that this is the natural outcome but it is only natural for us. Maybe an ailen civilization just doesn't give a bleep about colonising galaxy or maybe some day we won't give a bleep either.

  • Tom
    Tom   1 months ago

    Because we have almost destroyed every primitive tribe we have connacted a really intelligent civilization will observe but not contact

  • Robbie8
    Robbie8   1 months ago

    In the beginning he spoke very well and I am so pleased he spoke of humans spreading our wonderfulness across the galaxies. The word he used for this selfless colonisation of all things was :- "INFESTED"!!! Well said young man!