Why We Might Be Alone in the Universe
Sign Up on Patreon to get access to the Space Time Discord!
Check out the Space Time Merch Store
Why does it appear, that humanity is the lone intelligence in the universe? The answer might be that planet Earth is more unique than we've previously assumed. The rare earth hypothesis posits exactly this - that a range of factors made Earth exceptionally unusual and uniquely able to produce intelligent life.
In upcoming episodes we’ll be exploring the anthropic principle and its two main versions - the strong and the weak anthropic principles. The strong anthropic principle tells us that the observed universe must be able to produce observers - including the contentious idea that this predicts the existence of universes beyond our own. But in today's episode we’re going to focus on the weak anthropic principle. It says that we must find ourselves in a part of the universe capable of supporting us. For example, in a planetary biosphere rather than floating in the void between the galaxies. This may seems tautological, but accounting for this observer selection bias is important to understanding why the universe looks the way it does from our perspective. And the weak anthropic principle is much more useful than that. When combined with the apparent absence of alien civilizations, it may tell us why intelligent life is incredibly rare in our universe.
Hosted by Matt O'Dowd
Written by Matt O'Dowd
Graphics by Leonardo Scholzer & Adriano Leal
Directed by: Andrew Kornhaber
Executive Producers: Eric Brown & Andrew Kornhaber
Special Thanks to Our Patreon Supporters
BIg Bang Supporters:
Alexander Tamas
David Barnholdt
David Nicklas
Fabrice Eap
John S
Juan Benet
matt miller
Morgan Hough
Quasar Supporters
Mark Heising
Mark Rosenthal
Vinnie Falco
chuck zegar
Danton Spivey
Donal Botkin
Edmund Fokschaner
Hank S
joe pearce
John Hofmann
John R. Slavik
Jordan Young
Joseph Salomone
Matthew O'Connor
Syed Ansar
Gamma Ray Burst
Adrian Hatch
Adrien Molyneux
Andreas Nautsch
Bradley Jenkins
Brandon labonte
Dan Warren
Daniel Lyons
David Bethala
Frederic Simon
Geoffrey Short
Graydon Goss
Greg Smith
James Flowers
John Funai
John Griffith
John Michael Kerr
John Pollock
John Robinson
Jonathan Nesfeder
Joseph Dillman
Josh Thomas
Kevin Lee
Kevin Warne
Kyle Hofer
Malte Ubl
Nick Virtue
Nick Wright
Paul Rose
Scott Gossett
Sean Warniaha
Tim Stephani
Yurii Konovaliuk

  • PBS Space Time
    PBS Space Time

    Hey Everyone! So this is our first episode released in 4K. Hope you enjoy the upgrade.

    • Zoltan Matey
      Zoltan Matey

      the universe is big enough to have repeating type of evolutions arrise on different places

    • Element Zero
      Element Zero

      *Brigham richins* Soooo close to being right. Buuuuuut wrong. It did eject radiation but in axis directions, up and down, creating bubbles above and below the galactic core. NOT throughout the galaxy. It didn’t spread through the whole galaxy, it didn’t trigger any technological explosion in our history or potentially wipe species out. Radiation is detectable and slowly decays, if our planet was exposed to a MASSIVE dose around the same time that Sagittarius A-Star burped and irradiated us, we would have corresponding data which matched the event to radioactive decay here on earth.

    • Matt Roberts
      Matt Roberts

      Do you have tweeter I have something to show you

    • Callum Booth
      Callum Booth

      @Valentino Popa right you are!!!!

    • Abdullah Shams
      Abdullah Shams

      Awesome Upgrade

  • Evan Eats
    Evan Eats

    Time and space only exist in our mind's they are not real, space has no properties Nikola Tesla the inventor of the modern world said this. Magnetism give's volume to the entire Universe. Mother Nature is more simple then 1+1=2. Centrifugal convergence and centripetal divergence, force & motion, inertia and acceleration. There was no big bang nor first cause. Nature and totality is more simple than you ever dreamed imaginable. But we human's have to quantify and make everything overtly complicated. Mother nature does not work how we like to think she work's. The simplicity of the Universe is more simple than 1+1=2, it's beautiful to understand this and see it in one's mind. Magnetism = Loss of inertia and the creation of space I.e. which gives volume to 100% of Nature. Di electricity or Electrostatic's Force and motion inertia and acceleration. The golden ratio from macro to micro everything is self seeking. A magnetic field is a torus and a hyperbaloid. Same shape's on the back of a pine cone, the spiral's of galaxies, flower's, facial symmetry everything in Nature follow this perfection of unity. Two most fundamental principle's of Totality Di- Electricity Magnetism force and motion inertia and acceleration, Centrifugal convergence and centripetal divergence. Mother nature is more simple than you've ever dreamed imaginable. But modern science make's it out to be something over complicated which is further from the truth. It's beautifully simple.

  • Horny Toads
    Horny Toads

    The Peekaboo Analogy! Everytime i close my eyes & youtube / my browser you all cease to exist. My consciousness has created you all and you all serve a unique function ... you all truly exist only for my pleasure! I have giveth life and shall taketh away! But your existence is not weaved out of thin air. There is science behind it! Your existence is much like a covalent bond where I have given you all a life but it exists because I have given you a purpose! Truly, it can be summarized that In a way I am your master and ur all my slaves! so *KNEEL & BOW BEFORE ME YOU TURDS!* b4 i decide i should *Restart* my laptop!

  • Sacred Oracle
    Sacred Oracle

    People who think they are the body have no idea about ETs. People who know the true layer of reality (Mind) are in a cosmos full of divine intelligences... Truthfully, a highly educated person is likely to be dumber than an ant when it comes to the nature of reality.

  • Sacred Oracle
    Sacred Oracle

    Try meditation...

  • john white
    john white

    I think the reason we have not seen anyone else, is that space is really, really big. All the math I have seen is that there should be at least 10 planets like Earth out there but again since space is really big and we have not been looking that long, we have not seen them.

  • D B
    D B

    Earths are not rare, we had three in our solar system. The reason life reaches a bottleneck is diseases, no species has yet beaten the race it’s in against the microbes.

  • xnonsuchx

    The jury is still out whether Earth has intelligent life.

  • Jaren Williams
    Jaren Williams

    the desire to find something else is what creates something else

  • fredocorleone

    Interstellar travel is probably impossible anyways with all the various asteroids crossing between the stars...look at a star...it's blinking for a reason...stuff is passing in front of it throughout its great distance from you. So even if we do develop fast forms of travel, the potential vessel will probably smash into something. A piece of dust could destroy an entire vessel if it's traveling at a high speed.

  • Savage Coconut
    Savage Coconut

    Wtf the moon 🌝? Helped regulate our planet, here I thought it to be eye 👁 watching us. Is it true we only see one side of the moon?

  • Ginger Nut
    Ginger Nut

    We are not intelligent. We are bacteria on a rock.

  • Self Discipline
    Self Discipline

    I just cannot believe people are still atheists. The more science finds out, the more we look in awe at the 10/500 chance that we exist. With no answers, science just dances around a creator, and makes wild claims that make Noah's Flood, look like a gentle stream.


    why do you think that the environment needs to be suitable for life, why not the other way around?

  • BigDaddyCool42

    We are made from the most abundant elements in the universe. Might not be rare. Universe is just so big

  • Venom Supreme
    Venom Supreme

    Actually there are 14 galaxies containing life bearing planets. This is very well documented.

  • Deep Ashtray
    Deep Ashtray

    We might just be alone in the universe because intelligence is an evolutionary dead end.

  • Tim Smith
    Tim Smith

    So, is the incredibly rare Earth one planet in a million, one in a billion, or one in a trillion? Even if it’s one in a trillion, there’s alien intelligent life out there somewhere. But we’ll never know.

  • Rob Sin
    Rob Sin

    And do you think that God made only one Earth....

  • Mark Tucker
    Mark Tucker

    I'm not even sure if I'm alone in my own house....

  • Gary Bevis
    Gary Bevis

    This planet has been visited by extraterrestrials for eons. I have seen once, a craft, I know it was not made by man. I am an engineer and I have seen with my own eyes, so that is proof for me.

  • Secret Asian_Man
    Secret Asian_Man

    He's much taller than he looks on Game of Thrones.

  • T L S
    T L S

    All this rare earth theory aside, a lot of people believe that since seti hasn't verified any alien radio transmissions, other space faring intelligent civilizations don't exist. But what if there's something better than radio that we haven't figured out yet? And maybe other alien civilizations discovered radio then quickly figured out the better than radio thing and that's why alien radio transmissions don't really exist, and humans are on the verge of figuring that out.

  • That0neIdiot

    Mars has almost the same tilt and day cycle as Earth and the only reason Venus doesn't have a magnetic field is due to a collision that slowed its roation to a crawl.

  • Lóránt Farkas
    Lóránt Farkas

    Because we have the wrong type of neighborhood?

  • Jtem

    Problem is, go up to your attic or highest window and toss out an entire barrel of marbles. Whichever way they all come to rest, the odds were BILLIONS to 1 against it happening... so obviously it was fine tuned that way!

  • Ken Johnson
    Ken Johnson

    "... apparent absence of alien civilizations ..." What makes it "apparent"? Because they haven't colonized the whole galaxy? Maybe one defining characteristic of "advanced alien civilizations" is that they are content to stay where they are. Fermi paradox resolved.

  • Jtem

    The Fermi Paradox is a itself a Paradox, where it posits that aliens are like us, who are not traveling the stars, thus they should be traveling the stars...

  • mrS

    We may never travel the galaxy Star Trek-style, but I’ll take an Expanse style future for man...

  • Fred Flintstone
    Fred Flintstone

    For what this guy's explaining deserves more than what the elements he understand..

  • Fred Flintstone
    Fred Flintstone

    Caught between the Moon and New York City. I bear the witness of the Moon and its orbit while the Earth stood still! It could have just as well have been the moon stood still and the Earth spun faster! And the second witness I had to witness what's a black hole in my face! While I was moving and traveling at a rate of speed.. consciously awake in the daylight. Absolutely where I was all alone and no people were around for miles and miles..

  • Dan Razzell
    Dan Razzell

    It may or not be the case that intelligences such as ours are rare in the universe. We don't know. It may or not be the case that intelligences such as ours are FEW in the universe. This is a very different statement than the previous one, but again we don't know. In an unimaginably vast universe (100 billion stars per galaxy times 100 billion galaxies) even extremely rare events are probably numerous in terms of absolute numbers. This is vastly more likely than that we are the ONLY intelligent species in the universe. We know with certainly that we do, in fact, exist. Sow all the doubt that you like about how uncommon such a development might occur, in fact it has. That's as much as we know. The rest is (relatively ungrounded) speculation, and while enjoyable is not likely to yield useful results without much more compelling evidence than we can expect from current efforts. Here are a couple of POTENTIAL sources of such evidence, to the extent that they help in some way for us to calibrate the probability of life or intelligence apart from our own planet: 1) Indications of primitive life elsewhere in the solar system. If life in any form can arise elsewhere, we have some basis to extrapolate how likely it might be in general. Then we're only one (rather big) step away from crudely estimating the probability of intelligent life in general. 2) Indications of intelligent life anywhere in the vast universe. There are several very strong reasons, however, why we may never see such indications. Among these are the age and size of the universe relative to our aperture of perception (in other words, in terms of human civilization we're not likely to ever be looking in the right place at the right time) and the inherent loss of signal to noise, due not only to distance but to developments of technology that we now must expect of another intelligent species. On Earth, we had a window of about 50 years where we were broadcasting signals radially in cleartext. Except for a residue of broadcast radio, we don't do that any more, because it's painfully inefficient. We now have code division multiplexing, which to an accidental observer looks like random noise. Moreover, it's highly directed, or cellular, so as not to waste signal energy. We're not pumping terawatts of cleartext into the universe, hoping for a reply after a few hundred thousand years. Why not? Because doing so for hundreds of thousands - or more realistically say two billion - years in the hope of possibly getting a friendly response (as opposed to, say, a hungry invasion) doesn't rationally serve us. And we shouldn't expect it to serve any other species either.

  • Fred Flintstone
    Fred Flintstone

    I quote. he said we see no evidence of aliens.. surely he speaks for himself. So many scientists show otherwise?

  • LightningAssault.com

    Intelligent life came from intelligent design. That's it.

  • Alivia Alivia
    Alivia Alivia

    we assume there is no other life in the cosmos assuming goverments dont hide info about other lifes that might have visited our planet lol ..and goverments dont seem to like share those info lol even in ggogle earth etc there are areas on planet earth that you cant see clearly ^^ imagine if they hide stuff in our own planet what other stuff they hide haha. One could say ..but scientist havent discovered anything ...havent they ? or they forced to not say :) also how about previous civilations that might existed on planet earth thousand years ago n maybe migrated to other solar systems ? history is full of ancient stuff highlighting weird space crafts etc lol Rare ? hahahaha

  • 19devin86

    you need to consider the distance between stars as well as the cross section of our galaxy when considering why some intelligent species haven't claimed it all... on top of that the assumption that our plantet would be interesting for every species might be rather off since oxygen might be toxic to some and other might need higher or lower gravity. on top of that it would need to be considered that we could in theory be a scientific experiment of an alien species or even ancestors of some of their pioneers... if you're paranoid we could be a crop just waiting for the harvester. on top of this it is belived that one of Jupiters moons might have liquid water that could in theory sustain life... but not as us, but something different. @12.13 it seems as if cause and effect might have been reversed since we would have been a lot different if any single factor of the planet was different (higher/lower gravity, less/more salt in the oceans or similar)... so most likely we could say the same if we were a species standing on a highly acidic planet breathing sulphuric acid rather than oxygen looking at earth thinking that life couldn't happen there

  • vjnt1star

    The fermi paradox assumes that life will always go hanging about into space. Let's not forget that we humans are on this planet only because a random asteroid killed off the dinosaures otherwise it is very likely they would still be here. They stayed on earth for 140 millions years if I remember correctly. So evolved life might be abondant in the galaxy but it just stays on its planet.

  • Turling Drome
    Turling Drome

    Excellent presentation.... the Americans could learn from this style.

  • Dj Wards
    Dj Wards

    Or we might be inflating our own ego and not be as intelligent as we think

  • Terry Moose
    Terry Moose

    The universe is almost 5 billion years old. We have been looking for life for 50ish years. Big brain people: Must be no life. Aliens: This is why we don't talk to you.

    • Fred Flintstone
      Fred Flintstone

      I'm quite sure that this guy is a descendant of Lucifer that was cast into this realm of existence. He is so cute his face with his body.. studied religion. warn people that the pig nose will be on Lucifers son. So be it we are the existence of that that was cast out from the presence of God or whatever exists beyond all matter. energy.gravity.magnetism..

    • Fred Flintstone
      Fred Flintstone

      The universe has been around for infinity ..where do you draw the line? were the Roots grow out of your head for your hair? Need to hire a shrink now? So you can live your destined age of your life? (Happy go lucky for that length of time only)

  • Nate Male
    Nate Male

    Anyone know the music around 8:05 ?

  • Ahmed Kadiwal
    Ahmed Kadiwal

    Life is resistance to entropy (Negentropy) It means an increasing entropy universe created resistance to it would be more common in a finite universe.

  • Eric Johnson
    Eric Johnson

    This argument should be renamed the Arrogant Argument. We’re special, we’re all alone, we’re the only life there is in the whole universe, (even though we haven’t been anywhere else). It’s equally possible that aliens from other planets have their own Prime Directive not to interfere in our evolution (and by extension not make contact in a way that makes it obvious they’re from somewhere else). It may be that there are already 3 different species of aliens among us... There’s one book that states ‘in the Grand Universe, there’s the potential for 7 trillion inhabitable planets. With the companion information that each time a planet is capable of supporting life, it is visited by a Life Carrier who implants life on it. Even the Air Force recently admitted to tracking a UFO... No Virginia, we’re not alone...

  • kava rabbit
    kava rabbit

    This is as lame as flat earth theory...

  • Jeff H.
    Jeff H.

    Yah, well, many of the things you describe as rare simply can't be discerned at great distances. "We might be alone" does not in itself exclude other types of beings that might interact with us in a mutually communicative manner.

  • Ultimaheart4

    is it possible that we all are from aliens the intelligent life that may have created us years ago because they ran out of resources and couldnt think of a way to survive without evolving to a new species that could live on this planet. where did all these stories of gods that predate Christianity and Catholicism come from? are we sure they are not stories of our ancestors that came from space to create us and on their dying days "help finish shaping us and sharing with us ideas etc? without re creating a dying species that couldve wiped out their own world and life? :O so many possibilities!

  • Adhi 1023
    Adhi 1023

    We are alone. We might find life elsewhere but as far as intelligent civilizations go, we're it.

  • Quarker1

    We are NOT alone.

  • Lavapop

    is he a lost older Jonas brother? or Jonas uncle?

  • Eucenor

    Perhaps the requirement is a solar system made from remnants of merging neutron stars as life could be made from that hypothesized strange matter( just watched kurzgesagt video on neutron stars)

  • JAS

    This is going to blow the flat earthers' minds. They don't like seeing Earth as a sphere. On a serious note. We simply cannot go that far into the universe to determine if intelligent life exists anywhere. Human brains are simply not advanced enough to go that far to find the truth, whether it be by probe, satellite, telescope, or human missions. We have no idea what really exists beyond our galaxy for one simple fact. NASA will NEVER tell us what they really find. If anyone thinks NASA tells the whole truth about what they find on the Moon, Mars, or anywhere, then it's time to stop sniffing the glue. Also, it would be impossible that only Earth is a perfect planet to create and sustain life. There are planets forming every day with new suns and new moons. Life finds a way, as Jurassic Park promoted so eloquently. Without going into a religious rant, because we all know how those go on here; if a divine force created us and created Earth, then why would it only be one planet with humans? Why would a divine force only tinker with one planet for its crazy science experiment? Why was Earth placed at just the right distance from the Sun as to not be too hot? Why couldn't we adapt to a hotter planet? Why can't we breathe underwater? Why do we look like tadpoles when we are in the growth process in the womb and not look more human? Why do we have our protective layers protecting the planet? Why was Earth the only planet to be protected? Why and why? Lots of why's. Maybe you can call it evolution, which is by far a more complicated and ever-changing process than we will ever understand. Maybe we are here by luck. But to say that we are alone in the universe is absurd. Evolution happens everywhere. Not in the same way as it has here, but it happens. So, intelligent or not, life exists elsewhere. Earth is just one of those places that life exists.

  • Brandon DeBella
    Brandon DeBella

    If people come back in time it obviously not to party

  • pen_dawg95

    It would be strong evidence towards the simulation theory

  • Lex K
    Lex K

    So if we're alone, those UFOs were government prototypes.

    • Mac Mini
      Mac Mini

      ...Or hallucinations, or optical illusions, or hoaxes, or .... just some natural phenomenon that remains .... unidentified.

  • Sudden Revelations
    Sudden Revelations

    We are alone. Any aliens near our level of development is impossibly far away

  • Freespirit

    Very interesting and clearly explained. Great video!

  • Sridhar Puram
    Sridhar Puram

    ...everyone is looking for something concrete and convincing, ...sometimes it feels like an intelligent design by the creator - God who placed everything strategically and created life, other times it's like the matter itself settled into stable equilibrium and life evolved by chance randomly, ...or it could be mix of both, God - the invisible hand, driving force and matter - the visible, physical aspect of it.

  • You Know Who
    You Know Who

    Flat Earth hypothesis

  • Catalin Catalin
    Catalin Catalin

    Just a clown from the future btw

  • Catalin Catalin
    Catalin Catalin

    By the way, there s no aliens, we are the aliens to conquer the Universe. Thank you!

Every Denny's Ever
887 миӊ.