Are Axions Dark Matter?
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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.
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  • Astromations

    Yes. Yes they are!

  • Ricardo González
    Ricardo González

    Great video!

  • Zepha21

    Are humans great apes?

  • ED_DY TV
    ED_DY TV

    Traduction arab plz💕

  • M W
    M W

    Did he do a 5 minute commercial for NORD VPN?

  • Daniel Coker
    Daniel Coker

    Its data, not data.

  • Heineken Skywalker
    Heineken Skywalker

    I did comment that it was a chimp.

  • So ein Spast
    So ein Spast

    I really like the Tekken 5 main menu music

  • James Black
    James Black

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

  • Verners Lejietis
    Verners Lejietis

    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

    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

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

  • Brenden Carr
    Brenden Carr

    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 Plew


  • Someone

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

  • Vini

    Background music sounds like Twin Peaks mystery song.

  • Vini

    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 Ronin

    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 az

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

  • Binyamin Tsadik
    Binyamin Tsadik

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

  • Dr.V

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

  • Make Racists Afraid Again
    Make Racists Afraid Again

    Please don't say "visa" versa.

  • Michael Sander
    Michael Sander

    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 Original

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

  • Badger

    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 Meyer

    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 Reardon

    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 Research

    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

    Calling us out. Geez

  • Roman Buehler
    Roman Buehler

    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

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

  • Net Tech
    Net Tech

    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 Scoundrel

    17 minutes of man talking to himself in the mirror.

  • ChefHomesteadMaker

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

  • Marcin Zieminski
    Marcin Zieminski

    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 78

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

  • Brad Bradson
    Brad Bradson

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

  • Tirlon Burke
    Tirlon Burke

    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 Asheck

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

  • Frank Jaeger
    Frank Jaeger

    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 Jones

    I love your content Cosmic Jesus.

  • shipmaster3

    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 Mist

    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 Artifex

    Anxious dark matter

  • Sister of Gaia
    Sister of Gaia

    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

    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

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

    • weylguy

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

    • Gareth Dean
      Gareth Dean

      *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

    Is this where all the perverted Globe Earthers hang out?

  • Scoring digits, son.
    Scoring digits, son.

    Maj kohoni? Nahe!

  • PouncingAnt

    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 Reyne

    "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

      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

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

  • Mtf

    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 D

    Really interesting episode

  • frysebox1

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

  • Lance Tschirhart
    Lance Tschirhart

    Great apes _are_ monkeys. Jesus Christ, these cosmologists..

  • Manu V
    Manu V

    Do I come here just to feel dumb!?

  • Art

    Had to downvote after the first two seconds :(

  • Bill McDonough
    Bill McDonough

    Matt, just to 'nerd all the way': the great apes (or Hominidae) are a Family within the infraorder Simiiformes... the monkeys. So strictly, all apes *are* monkeys. Catarrhini 'Old World' monkeys, in fact.

  • Gabriel Desmarais
    Gabriel Desmarais

    I guess it is official, we can't out-nerd Matt.

  • Kez

    Can you be straight and wear a pink shirt into a gay bar?

  • Jason Williams
    Jason Williams

    How can observable time not affect observable mass

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