Are Axions Dark Matter?

For more information go to: and use the code: spacetime
Sign Up on Patreon to get access to the Space Time Discord!
Check out the Space Time Merch Store
What does the strong nuclear force, the fundamental symmetries of nature, and a laundry detergent have in common? They’re all important parts of the tale of the axion - a tale whose end may take us beyond the standard model and solve one of the most vexing mysteries in astrophysics.
Hosted by Matt O'Dowd
Written by Matt O'Dowd & Graeme Gossel
Graphics by Leonardo Scholzer & Adriano Leal
Post Production: Yago Ballarini, Max Willians, Pedro Osinski
Directed by: Andrew Kornhaber
Executive Producers: Eric Brown & Andrew Kornhaber
The story of the axion is a classic physics tale: intrepid scientists delve deep into trackless mathematics in search of answers to a mystery. And there, against all expectations, they find the hint of a completely new and unexpected denizen of the natural world. In this case the mystery was a subtle inconsistency in the behavior of the fundamental forces. And the unexpected discovery? A brand new particle - the axion - which, while not proven to exist, may explain a much more famous conundrum. The axion may explain dark matter.
Special Thanks to Our Patreons
Big Bang Supporters
Alexander Tamas
David Barnholdt
David Nicklas
Fabrice Eap
Juan Benet
Justin Lloyd
Morgan Hough
Quasar Supporters
Christina Oegren
Mark Heising
Vinnie Falco
Hypernova Supporters
Chuck Zegar
Danton Spivey
Donal Botkin
Edmund Fokschaner
Hank S
John Hofmann
John Pollock
John R. Slavik
Jordan Young
Joseph Salomone
Julian Tyacke
Justin Ash
Matthew O'Connor
Syed Ansar
Timothy McCulloch
Gamma Ray Burst Supporters
Adrian Hatch
Adrien Molyneux
Andreas Nautsch
Angela Prigge
Bradley Jenkins
Brandon labonte
Brian Blanchard
Craig Stonaha
Dan Warren
Daniel Lyons
David Bethala
Douglas Cantrell
Eric Kiebler
Frederic Simon
Geoffrey Short
Graydon Goss
John Funai
John Robinson
Jonathan Nesfeder
Josh Thomas
Kevin Lee
Kevin Warne
Kyle Hofer
Malte Ubl
Michael Conroy
Nick Virtue
Nick Wright
Nickolas Andrew Freeman
Patrick Sutton
Paul Rose
Protius Protius
Robert Ilardi
Scott Gossett
Sean Warniaha
Shane Calimlim
Sipke Schoorstra
Steve Bradshaw
Tatiana Vorovchenko
Tim Stephani
Tybie Fitzhugh
Yurii Konovaliuk
Randall Sylvia


  • Gregorii Katastrov
    Gregorii Katastrov22 цагийн өмнө

    "W" in Wilczek you should've pronounced as "V" (like in "View") and it mean puppy-wolf in Polish (don't know if Frank is Pole, but i'm pretty sure, he at least had polish ancestors). Sorry, couldn't stop myself - it was first time i felt competent enough to correct you. Great job on what you are doing.

  • Francis
    FrancisӨдрийн өмнө

    Does this so-called dark matter even exist? Probably not

  • The Internet Dinosaur:
    The Internet Dinosaur:Өдрийн өмнө

    ;Love this channel so much, i am always nerding out on this! :)

  • Ryan
    RyanӨдрийн өмнө

    love the videos but what's with the low frame rate?

  • Logesh K
    Logesh KӨдрийн өмнө

    If axions have mass then how can they be interconverted into photons....??? Please explain (since photons have no mass)

  • MeeK1447
    MeeK14472 өдрийн өмнө

    This is similar to a theory that I thought of, my theory involves 4 dimension, Dark Matter, and Electrons. My theory is that, when an entity or object is bound to a single point, there are many new possibilities being created by them simply existing. But in a 4 Dimensional universe there is no possibility because it all happens at once. there is an effect due to the 4D Universe, that I believe takes place when 3 Dimensional universes interacts between those universes. When an object or entity is in the same location at the same time, with every atom precisely in the same position. Quantum Entanglement gets involved, and they just 'Flow' through the 4 Dimensional universe, slices of the 3 Dimensional universe that are so close to one another they start to interact with each other, but at the smallest scale only. Electrons really run our universe. Even this phone I'm using. 4 dimensions to me is just the many worlds theory. Dark Matter is not known but I believe I have solved it, and a way to get small proof. So My Theory is that if Electrons are so small, they can be considered as a point. But when they are unable to interact with any matter, like say in a deep space Vacuum. Those Electrons create a 4 dimensional 'flow' through spacetimes because they are bound to a single point, which is the atom. This 'flow' of electrons is not creating new electrons, but they are existing simultaneously. What I mean is that for every possible location the electron CAN exist at one point in time, it does. Electrons becomes 'solid'. The electron has it's own state of matter, the opposite of plasma, it's a 4D object that becomes 'full' in our 3D reality when the environment of that electron is right. 4D Electrons, Exist in an Exothermic reaction, in a Vacuum at the small scale, with near absolute zero temperatures, at zero G. 4D electrons only exist when there is a lack in temperature, surrounding matter, and a lack of gravity. Basically when nothing happens, the universe loves balance, so something happens because of the lack of potential. Now take an Electrons mass multiply it by the number of points of possible locations it can exist at once. Next, 4 dimensional mass of an electron multiplied by the Mole (6.02x10/²³) now you can test this theory by comparing that to the mass effects of Dark Matter, but I ain't good at math. I can't do astrophysics but I love Science. Fun fact, if this is true, take a good look at the mandelbrot set, imagine that the edge in the black is earth. Now imagine each point being one earth, you keep zooming in you see more area it could exist, almost to infinity because of fractals. And we live in one, Beautiful. Thanks for Reading, Goodbye.

  • Joye Colbeck
    Joye Colbeck2 өдрийн өмнө

    A weakly interacting small particle - a WISP?

  • Astromations
    Astromations3 өдрийн өмнө

    Yes. Yes they are!

  • Ricardo González
    Ricardo González3 өдрийн өмнө

    Great video!

  • Zepha21
    Zepha214 өдрийн өмнө

    Are humans great apes?

  • ED_DY TV
    ED_DY TV4 өдрийн өмнө

    Traduction arab plz💕

  • M W
    M W4 өдрийн өмнө

    Did he do a 5 minute commercial for NORD VPN?

  • Daniel Coker
    Daniel Coker4 өдрийн өмнө

    Its data, not data.

  • Heineken Skywalker
    Heineken Skywalker4 өдрийн өмнө

    I did comment that it was a chimp.

  • So ein Spast
    So ein Spast4 өдрийн өмнө

    I really like the Tekken 5 main menu music

  • James Black
    James Black5 өдрийн өмнө

    Watching you move I think your camera's exposure time is too small.

  • Verners Lejietis
    Verners Lejietis5 өдрийн өмнө

    Wow! Even though, the Consiousness influencing QM video is more to my liking, I am glad I did not miss this one. I went in it without a clue what an Axion is, but your explanation with the graphics was top notch. If only i was a kid way back in school, your content is really inspirational.

  • CleverWire
    CleverWire5 өдрийн өмнө

    In an infinite sized universe bag (for lack of a better sciency word) that contains infinitely sized universes where the bag's existence expanded infinite time wouldn't the probability this text message be typed already in the past by an identical me be 100%?

  • pvc
    pvc5 өдрийн өмнө

    "CP Violation" Attention, ground units - anti-citizen reported in this community. Code: lock, cauterize, stabilize.

  • Brenden Carr
    Brenden Carr5 өдрийн өмнө

    3:36 okay wow, the strong CP problem really sounds like the intersection in which we need to keep a very close eye on. Our error, our missing connection, lies somewhere in the maths which cause this mismatch. I absolutely love it! I almost want to go to college to learn everything about these problems, just so I can help figure it out. It's so exciting and enticing, to see things like this unsolved to this day

  • Sazy Plew
    Sazy Plew6 өдрийн өмнө


  • Someone
    Someone6 өдрийн өмнө

    I think a better term for "symmetric" is.. Bipolar.

  • Vini
    Vini6 өдрийн өмнө

    Background music sounds like Twin Peaks mystery song.

  • Vini
    Vini6 өдрийн өмнө

    The standard model / QFT is slowly reaching its limit. Extrapolating from already existing equations will eventually just make you go in circles. You need some genuinely new ideas.

  • King Ronin
    King Ronin6 өдрийн өмнө

    My question is why is a chiral neutron predicted to have an electrical charge? The positive version of an electron and a negative proton should mathematically produce a neutron of the chiral constituents but of similar basic properties?

  • civota mu az
    civota mu az6 өдрийн өмнө

    Would watch this whole video but goddamn it feels like Billy Mitchel is waterboarding me

  • Binyamin Tsadik
    Binyamin Tsadik7 өдрийн өмнө

    Check out this paper: You are saying the same thing.

  • Dr.V
    Dr.V7 өдрийн өмнө

    Wonderfully informative and fantastically interesting. Thank you kindly @PBS Space Time for making this.

  • Make Racists Afraid Again
    Make Racists Afraid Again7 өдрийн өмнө

    Please don't say "visa" versa.

  • Michael Sander
    Michael Sander7 өдрийн өмнө

    To me, PBS Space Time is single best physics channel for folks who studied college-level physics, but didn't quite make it to (or through) physics grad school. Agree?

  • Inspiración Original
    Inspiración Original7 өдрийн өмнө

    so... this means the Axiom could be used to support photon decay as an explication for dark matter?

  • Badger
    Badger7 өдрийн өмнө

    I think axions and the theory itself could for the most part be replaced with formative causation as an account for dark matter/energy or other potential issues in our simulations.

  • Charlie Meyer
    Charlie Meyer7 өдрийн өмнө

    A proton-like composite particle made of Axioms could get a lot heavier! A "Protaxion" might even move sub light speed despite its superluminal parts.

  • Kevin Reardon
    Kevin Reardon7 өдрийн өмнө

    Dark matter only exists because we are memorized by the three body problem. The Moon and Earth are gravitationally locked, which is the same effect you see with the outer stars of a galaxy. There is no dark matter, there are gravitational rings on the outer reaches of a galaxy.

  • Exoplanet Research
    Exoplanet Research7 өдрийн өмнө

    There are galaxies with barely any dark matter. They should map the total magnet fields for the galaxies, then compare the dark matter content

  • Clickmaster5k
    Clickmaster5k7 өдрийн өмнө

    Calling us out. Geez

  • Roman Buehler
    Roman Buehler7 өдрийн өмнө

    let me nerd away in my own world: that noise... what's that noise?!?!?! in ALL your videos, it's driving me insane and i have to focus hard on what you say... there's the music in the background, and there's you speaking, but there's also a noise, probably peaking around 600-800hz all over the videos... is that intentional by the editor to avoid hearing fatigue because of too clean sound? -> better way would be to use light audio compression on the voice track... is that because your recording environment is so noisy? -> with your budget you really should get better accoustic padding and isolation... is your editor hearing impaired and he never noticed? -> run some analysis on the sound output, find it and fix it, please!!!

  • Roman Buehler

    Roman Buehler

    7 өдрийн өмнө

    it appears to be the mic input... FIX PLEASE!

  • Net Tech
    Net Tech7 өдрийн өмнө

    Off topic, I know it is mathematically and physically possible to add positive mass to a point of spacetime but I'm curious if it is mathematically possible to add negative mass to a point of spacetime. A blackhole adds mass to a singular point by consuming mass increasing mass and gravity bending spacetime one way but is it mathematically possible to do the opposite creating negative mass effects to bend spacetime the inverse way?

  • Audacious Scoundrel
    Audacious Scoundrel7 өдрийн өмнө

    17 minutes of man talking to himself in the mirror.

  • ChefHomesteadMaker
    ChefHomesteadMaker7 өдрийн өмнө

    That Thing That Newton Wrote, is it a must read?

  • Marcin Zieminski
    Marcin Zieminski7 өдрийн өмнө

    There are 4 fundamental forces, and lots of different particles. How do scientist now which particle interacts with different forces? Ex.axions interact only with gravity and weak force, my question is why they interact only with those two forces, ? What is the mechanism behind it? Are there any laws which tell us that any given particle will interact with any given fundamental force?

  • Chrizzie 78
    Chrizzie 788 өдрийн өмнө

    Does any of this matter?! Thank you, you've been a great audience.

  • Brad Bradson
    Brad Bradson8 өдрийн өмнө

    Maybe there is no Dark Matter, maybe there is many Dark Matters

  • Tirlon Burke
    Tirlon Burke8 өдрийн өмнө

    You recently did a show on infinite universes and possibly the infinity of our universe. If either is the case, shouldn’t there be a wormhole we could traverse somewhere accessible on planet just waiting for someone enterprising to push a monkey through into a magnitar and one for us to travel somewhere slightly more pleasant?

  • Imgay Asheck
    Imgay Asheck8 өдрийн өмнө

    This channel still believed in inflation so I'm going to guess no

  • Frank Jaeger
    Frank Jaeger8 өдрийн өмнө

    I believe that in Latin the letter "c" is always pronounced as the letter "k". So the second way you pronounced it would be the most correct.

  • Max Jones
    Max Jones8 өдрийн өмнө

    I love your content Cosmic Jesus.

  • shipmaster3
    shipmaster38 өдрийн өмнө

    Do you think that there is some relationship between the photon energy and the strength of a magnetic field needed to convert it? or is it just a sufficiently strong magnetic field is needed to any photon into an axion regardless of energy ?

  • Cierra Mist
    Cierra Mist8 өдрийн өмнө

    If the spin of a black hole can rip away its event horizon revealing a "naked singularity", would all the mass that's in the singularity come exploding out? Maybe the big bang was an event like this?

  • Manus Artifex
    Manus Artifex8 өдрийн өмнө

    Anxious dark matter

  • Sister of Gaia
    Sister of Gaia8 өдрийн өмнө

    If you take the remove the first 5 00000 from the quantum vacuum number measurment of the Universe. It would explode 💥 and we would not be here 📌

  • weylguy
    weylguy8 өдрийн өмнө

    Wow - explaining an undetectable form of matter with another undetectable form of matter. Turtles all the way down? But I love this PBS program!

  • Gareth Dean

    Gareth Dean

    4 өдрийн өмнө

    Pretty sure it's been solidly disproved. But hey, flat Earth has made a comeback too.

  • weylguy


    5 өдрийн өмнө

    @Gareth Dean 130 years later, the aether theory is still awaiting confirmation.

  • Gareth Dean

    Gareth Dean

    7 өдрийн өмнө

    *Currently* undetectable. The hope being of course that we CAN detect it Nobody's sitting in bed going 'Boy, I hope we find nothing tomorrow!'

  • mettaur01
    mettaur018 өдрийн өмнө

    Is this where all the perverted Globe Earthers hang out?

  • Scoring digits, son.
    Scoring digits, son.8 өдрийн өмнө

    Maj kohoni? Nahe!

  • PouncingAnt
    PouncingAnt8 өдрийн өмнө

    Excellent. Sounds like Axions are an elegant solution to at least two big physics problems. Which leaves the question, Why might they not be? Is there anything besides the lack of experimental evidence to justify the title of the video being a question rather than a statement? (Of course, experimental evidence is a requirement of the scientific method, but.. you know how when they hype a particle, then you go and see the particle, and it's not as good as you were expecting...) P.S. A lot of people thought that about the Higgs.... But I thought it was a massive success. P.P.S. Sorry

  • Amari Reyne
    Amari Reyne8 өдрийн өмнө

    "The universe may be truly spatially infinite" Even though I already had that idea in my head, hearing the words out loud from someone else really melted my mind. There's so many things we will never even begin to understand before the heat death of our own part of the whole universe. I mean, we used to think the milky way was the whole universe. And we were calling Andromeda an "island universe" What's to make anyone think the universe we observe isn't just one of... Billions? Trillions? Infinite? Universes. Guess we will never know 🤷‍♂️ I havent slept in 27 hours, go easy on me if you reply 😅

  • Zenothys


    8 өдрийн өмнө

    Amari Reyne You have a healthy skepticism and an inspiring curiosity. No reason to worry about responses imo! To give my two cents, space is only as large as needed to contain all possibilities (which I believe isn't infinite, but does inflate fast enough to redefine infinity to some larger number the instant the previous number is defined), and once you hit the "edge" of space, space becomes _time_ and more or less travels back to the Big Bang via the "beloved" Bogoliubov transformation.

  • Cheasy
    Cheasy8 өдрийн өмнө

    a nerd channel and no 60 fps xD yr tittle has been revoked

  • Mtf
    Mtf8 өдрийн өмнө

    I used to watch these videos and then, frustrated for not being able to understand, go to the pub . Now I 've thought better and I go to the pub BEFORE watching the videos and suddenly they are crystal clear .

  • Doldol D
    Doldol D8 өдрийн өмнө

    Really interesting episode

  • frysebox1
    frysebox19 өдрийн өмнө

    Me: Officer, why am I being detained? Officer: 2:18