The Story of Dark Matter | Crash Course Pods: The Universe #6

"How do we know that dark matter is there?"
In this episode, Dr. Katie Mack and John Green unpack the full story of dark matter.
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[@NathanaelNewton]

I feel like there's a good chance that this series of videos will be as influential to some future young scientists as the cosmos series with Carl Sagan was for some previous generations ❤❤❤

[@gibberishname]

I watch this podcast 10% to learn new stuff (I double majored in Physics, and _loved_ astronomy, so I have a cursory understand of what Dr. Mack is explaining), 30% to feel moved as John learns new stuff, and 60% to hear the amazing ways John Green will turn the wonder of understanding our place in the universe into a *SEGUE TO A COMMERCIAL FOR LIFE INSURANCE. 10/10 no notes*

[@calypso.s]

This series is incredible and Katie is such an excellent science communicator. She puts things so eloquently and John does an excellent job asking questions to get more answers, as well as recapping things with great summary. I love this series with my entire heart.

[@civail5699]

Same. I see myself coming back to this series a lot in the future (and not only because I know I'm only really able to wrap my head around a fraction of the physics lol)

[@HighPrior]

Dear Subtitle team. at 52 minutes Katie talks about 'parity', and is incorrectly subbed as 'parody'. No shade, I love all the hard work

[@crashcourse]

Uh oh! Good catch. This was an error on our part!

[@dustinking2965]

So is the next episode "Dr. Katie Mack talks about dark matter for 5 more hours" because I would watch that episode.

[@LawTaranis]

I need 1000 episodes of Katie and John. I love this so much

[@massimocole9689]

Yes! So glad this show is continuing. I wasn't sure if it was recorded on advance and was afraid it was canceled due to John's hiatus. I hope your rest is going well John, you deserve it.

[@NathanaelNewton]

Fun fact, positron emission tomography, commonly known as a PET scan, uses the 511 KEV annihilation of antimatter generated by the anthropogenic technetium 99 metastable as well as a number of other radioactive elements to map the inner workings of living processes and give us diagnostics information that previous generations could only have dreamed of in a full-on Star Trek sort of way.

[@kuro_okami2044]

I would love to listen to the Dr. Mack 5 hour version of this episode! I am fascinated by dark matter and our search for it and will listen to as much as Dr. Mack is willing to share which sounds like a lot!

[@alyeverything4642]

I look forward to this podcast more than any other video on youtube thank you guys!

[@SunlightHugger]

I used to have a story idea where future humans decide to go back in time to witness the Big Bang and end up being the matter that unbalanced the antimatter equivalent annihilation.

[@darbymori350]

I LOVE this series. Thank you for creating it

[@dylangreen6075]

This series is fantastic. Thank you guys so much!

[@okuno54]

This is actually the first time I've really been convinced that dark matter really is a thing (even if we don't know what it is). Thank you so much Katie for making it so much easier to understand after 15 years! I went to university for physics, so I've always been skeptical (in the actual science way), but never got to the point where I could evaluate the scientific papers and the state of research. I can finally put to bed the mental noise of wondering whether dark matter is too manipulable a solution

[@ExoticTerrain]

I can’t express how much I’m loving this series! Thank you guys!

[@chrishill7797]

I could listen to this Dr all day long. Engaging and so enthusiastic! Love it!

[@whiteathame808]

Love this series so much

[@Alice_Walker]

Thank so much for bringing us such a beautiful blend of human awe & angst with kick ass science. This is such a wild and wonderful series and I loved this episode particularly. I feel sure that the giants who came before you both will be happy to have you on their shoulders telling the stories! 💜

[@crashcourse]

Thank you for all of the kind words and for supporting our channel!

[@krellend20]

My burning question now is "how are neutrons not dark matter?"

[@CompiledGabriel]

Seriously, whoever thought about promoting life insurance with this series need a raise immediately. "Wow, this is really heavy existential dread... let's sell insurance with it!"

[@melimelon5368]

10:47 til that Ive been mispronouncing cherenkov radiation for several years now

[@NYR14477]

I wish so much that there were diagrams with this so I could understand it more

[@anitsingh483]

Thank you for such a detailed discussion and all the great nuggets in between!

[@cfromnowhere]

That LIGO concrete barrier story is wild. I guess it is the one in Louisiana because it is in the South?🤣 I cannot find any other sources online about this anecdote either, so this may be the first time anyone from the physics community has told this story. Katie, you are the first this time!

[@Davlavi]

Informative as always.

[@cheesypotat0es]

I like listening to Dr. Macks lectures

[@divisionisfakenews197]

The circular staircase described sounds like something out of "A House of Leaves"

[@danielbaulig]

A question: the reason that not all matter just collapses into singularities due to its own gravity is (at least at some level) electromagnetism. E.g. the reason earth doesn’t just collapse in on itself is because all this Earth stuff pushes against itself and will not compact more at some point. The same is true for stars like our sun: the reason they do not just collapse into singularities is the pressure created by the nuclear fusion in their cores, which is also electromagnetism. In the episode you gave the example of the intergalactic medium that should be less dense and less hot - caused by pressure due to electromagnetism. How is it that dark matter doesn’t just gravitationally collapse down in on itself? Why does it form “bubbles” around galaxies instead of just being pulled into the center? The intergalactic medium is more dense and hot than we’d expect because of dark matter but it’s hot and creates outward pressure because of its electromagnetism. What keeps the dark matter “in shape”?

[@iza63lla]

Thank you!

[@manymuchmoosen7088]

Thank you so much. That was the most detailed and new quality information on dark matter/energy I’ve ever heard. She went way beyond just what it is basically defined and went into many of the actual details. THANK You both.

[@Ellohir]

I knew about Dark Matter in general but it's nice to learn the specifics: - Adding a ball of dark matter around a galaxy explains the speeds of the orbiting starts in the spiral arms. - We see gravitational lensing around galaxies but not in the interstellar medium gas. Those are smoking guns for Dark Matter, it looks really hard to explain that with Modified Gravity.

[@aosidh]

I think I missed it - did Dr Mack talk about how all normal-matter neutrinos seem to be left-handed? That seems like something that would bother John 😹

[@edstauffer426]

Since the 1990’s we have also entered the S1 dark matter stream which is going the opposite direction around the Milky Way to what the solar system is.

[@CatsMeowPatel]

Thank you. This was fun.

[@descentplayer]

It was episode 6 when I noticed 2 people sitting in the foreground looking at the stars. Of course, most of the time, I am just listening or watching the subtitles or the pulsar pulsing.

[@acetrainer5564]

I consider myself to be pretty well educated about these things, and I still learned from this. Excellent work.

[@jamesonpace726]

Just marvelous! How cool it must be to do this as a career- if I were young, I'd be an astrophysicist & the math, well, that was always the problem for me, but I just love this hard stuff....

[@carpemkarzi]

I am so loving this series. It is so blissfully matter of fact. It shows what we have done and learned and are doing and learning. Oddly enough I knew about the ship steel as I once visited a whole body counter that had to be shielded with that same ship metal. It’s just all so damned neat.

[@bardigan1]

It's electromagnetism, all the way down!

[@benhoffman6606]

Doesn't speed have a gravitational effect? If the galaxies/ universe was moving/ expanding, wouldn't that energy have a bigger effect than we would experience more locally?

[@Viriatha]

Sagittarius A* is an AMAZING name.

[@HUBBLE724]

Amazing video

[@joangopin4022]

Maybe this is just my lack of understanding of this stuff, but if the supermassive black hole in the center of our galaxy is warping time such that the things that are close to it appear to be moving slower to us, since we're beyond its event horizon, perhaps the relative speed of of the outer stars in the spiral arms of the galaxy are not really moving at the same speed as the ones closer to the center?

[@dankus2323]

I’m reading your book about the end of the universe rn

[@jl9088]

How does the world change? Ther'es always something that leads to change but what really causes change? Change is constant but... how does it change?

[@lillion3560]

Let them through I don't have problems with that 🗿

[@psalmy26]

I don't know if any show can ever match up to this... Set of saguas to a sponsor. X.x

[@rox4884]

Your comment about the spiral staircase made me think if Nobel and how he started the piece prize so people would remember him for something other than dinomite. He isn't responsible for the way that it was used though. He invented it because it was more stable than what miners were using. Same with Einstein. It's not his fault that Truman dropped one bomb, let alone two. Also, I don't know if John realizes the implementations of what she told him, but he didn't actually touch the apple 😉

[@timwlake]

I had heard, what I felt like was a lot about dark matter, but I have never heard about the energy excess from the center of galaxies and how it may be a sign of dark matter decay. Also, dark matter decay is a thing? Of course it is. That's so obvious in retrospect. Anyway, thanks for blowing my mind about dark matter.

[@EarendilStar]

If 85% of matter in the universe is dark matter, and dark matter obeys the force of gravity, are 85% of black holes also dark matter? If not, why not? If so, I’m slightly comforted by that :)

[@shadebug]

The chances of neutrinos interacting with your body are a trillion to one they say The chances of neutrinooooooooos interacting with your body are a trillion to one Yet still they come

[@charlotteh7512]

i love it here

[@CadoPack]

Imagine if aliens made a ufo out of neutrinos. They could fly with almost perfect efficiency

[@kaikash]

I read and looked into a story of a particle going through a computer, changing a bit, and causing a game to teleport the character. A guy was playing Mario 64, and a particle (I forget which while typing this) passed through his PC at a specific angle that pushed a bit to the next number. Is that an example of "You'll only interact with a neutrino once"? We are constantly being bombarded, but only once in a lifetime does it interact with something on the way through.

[@kaintshine]

Did everyone pause at the end of the bullet cluster explanation, study the picture, then rewind the explanation and go, "Ohh, I get it!"

[@MakeMeThinkAgain]

I thought dark energy would be next. Did we already do that?

[@car2804]

So interesting i love it, thanks!❤

[@swagilyph]

Is the annihilation of matter and anti matter at the beginning of the universe noticeable in the CMB in any way?

[@Roadiedave]

Wow

[@civail5699]

Problematic steel kills on the runway

[@StrayVagabond]

Hmm... Could the phenomena we observe with galaxies be caused by unidentified curvature of space time? Like... Maybe galaxies exist where they do and function the way do because space time is curved differently there

[@tb22k]

❤❤❤amazing 😅

[@fromulaon]

Ooooh could it be just matter from future or past that somehow curves space through time? 36:40

[@ILikedGooglePlus]

Of course Dark matter. Dark how was your day?

[@BrandonTaylor-w7y]

Help

[@sarahleonard7309]

Alright, I have to know. When she described a spiral galaxy as a disc of visible matter embedded in a sphere of dark matter, did anyone else picture the end of the first Men in Black movie, where the cosmic being is playing marbles with galaxies? (They may have been universes, not galaxies. It's been a long time since I last watched that movie.)

[@flytape8490]

Why are people shooting at LIGO

[@fromulaon]

Could dark matter be just anomalies in space where somehow the fabric of space has curved a lot for no reason ? 34:44

[@drex23100]

Think of it this way. Dark matter is simply the fabric of spce/time. It is not a field that is everywhere which surrounds and is inside space, it IS the space.

[@jl9560]

I think Einstein was right in the fact that space is made out of the same thing matter is. In that regard, what we attribute to dark matter is actually just space itself being clumped up just as matter does.

[@Tr4cK17]

My bet is still that empty space itself is "heavy"

[@parvazebhat9058]

So, is it becoming more plausible to believe in the Unseen day by day.

[@m.rstudy9813]

2nd

[@reginat5749]

First off, I really, really love this series. But I think I need to watch some make-up tutorial or puppy video to come back to myself again, now.🫣