Hey Space Timers! Last week we found that some audience members experienced audio issues as the result of KZread's processing of the video. We've made the adjustments we can to improve the audio experience, but we are currently discussing the matter directly with KZread. If you experience any audio issues, please respond to this comment with the time code and what you're experiencing. This will help us as we work through the issues with KZread.

@zhadoomzx

10 ай бұрын

0:36 - first word you speak. Then again at 0:51 - on the words "even to allow". Slight, quick, unnatural variation in your voices pitch... like a tiny bit auto-tuned. Then at 1:27 on the word "something". 8:24 on the word "through".

@osmosisjones4912

10 ай бұрын

If wormholes were real wouldn't the gravity on one end pull the gravity at the other. And they close so fast stretch and contract slowed down and speed up light all affects on light would be cancelled out

@wmpx34

10 ай бұрын

@@zhadoomzx Yeah same here

@ivantsivrostyslav

10 ай бұрын

usually i listen to youtube on volume set to 4, but to hear your videos i have to set the volume on 9

@nulledabyss2230

10 ай бұрын

@@ivantsivrostyslav Yeah they are unusually quiet

The idea of a particle with a de Broglie Wavelength of lightyears breaks my preconceptions about quantum field theory, and I love that.

@WestOfEarth

10 ай бұрын

Nicely said

@hherpdderp

10 ай бұрын

Something i have wanted to ask. Can radio / light have wavelenghts this long? Obviously we cant make antenna big enough to test thism

@connerwalsh1257

10 ай бұрын

​@@hherpdderpyes. Similar to gravitational waves having wavelengths that are light years long. Pulsar timing and other interferometry experiments may reveal many things

@dougg1075

10 ай бұрын

Yeah!

@Joker-no1fz

10 ай бұрын

could dark matter be strange matter? why do we never see regular matter directly near dark mater makes me think it is strange matter.

Something that's important to remember is that axions are originally a prediction of another mystery - they are supposed to resolve the strong CP problem in quantum chromodynamics. Or basically why matter even exists. There is no better explanation at the moment that explains this oddity. So there's a super high chance that they do exist There was a study this year that suggested we can find axions by using extremely powerful accelerators with ionic particles inside in order to force interaction with incoming axions that would result in observable effects. Something that could be achieved in the next decade or so assuming there's interest

@anubhabmaiti9658

10 ай бұрын

Big fan anton. Didn't hope to find you here

@WilliamFord972

10 ай бұрын

Hi, Anton!

@tekila00985

10 ай бұрын

I wish I had more likes to give this comment.

@georgegordian

10 ай бұрын

Hello, wonderful person :)

@speedymccreedy8785

10 ай бұрын

No, can it be, it’s not even plausible, but yet here he is. The famous dark matter unicorn cowboy Anton has arrived. Tada. Straight from the dark matter unicorn parking lot on Uranus.

I love when previous episodes come together into an episode like today's. Awesome job Space Time crew!

@adamhanninen8295

10 ай бұрын

Yes but the actual local DM density is ~0.4 GeV/cm^3 which puts Matt’s value off by 2M. While no one knows the mass or flux, the mass is also likely to be just sub-GeV I betchya

@meesalikeu

10 ай бұрын

if axionic dark matter exists, then as a kind of superfluid it would make alchemists of olde correct in their belief in the aether. so for stitching together that deserves a shout out too.

@petepanteraman

10 ай бұрын

​@@meesalikeunow that you mentioned it I would agree with you, lol axion = aether

Aww I missed this type of "cutting edge", deep cosmology/quantum theory topics. I love that

I really love this idea and am very grateful to Spacetime for introducing me to it. It's a wonderfully weird solution that somehow feels intuitively "right" in some way. Other dark matter solutions always leave me feeling like we are missing something that should be obvious. There's just something beautifully elegant about the idea of quantum waves that are light-years across. Whether or not it is proven to be correct, it has a beauty to it to rival the greatest works of art. It's both simpler and weirder than Ant-Man's so-called quantum realm, while still being consistent with known reality. If Axionic Dark Matter ends up being wrong somehow, I hope and suspect it will be because nature is even more beautiful and weird. This is one mystery in which the journey is more exciting than the destination, and I am lucky to be along for the ride.

Really love how this channel explains the *possible* physics behind the cosmology observation we're currently seeing with new discoveries.

This has been one of your better episodes recently. Great stuff, can't wait to hear you guys cover the gravitational wave announcement that's due tomorrow.

Simply the best explanation of axionic dark matter I've seen yet! Thanks Matt

Congratulations, your way of explaining things is ..super fluid. (I guess this sentence works in English, as well as in French).

I mean despite the fact that I get my QM knowledge here( of course in another lifetime I would love to be proficient in the sciences) this has pretty much been the channel that has made me fall in love with physics. I’m curious though, is there going to be a video on the recent developments on Sagittarius A? Black holes are so interesting and getting to understand what’s going on and what it means would be great. Thank you again Matt!!

Question: With such long wavelengths, how would Axionic Dark Matter behave close to the supermassive blackholes seen near the center of galaxies? Would something about this black-hole "pin" the super fluid to the blackhole and then be a place where gravity would pull normal matter to during the development of the galaxy.

@Crushnaut

10 ай бұрын

I have a similar question so I will include it here. How would an extremely light axion interact with a black hole? If you had a black hole with a mass of 10 suns, it's Schwarzschild radius would be approximately 60km. Some of the light axion's you mentioned have wavelengths much much greater than this, say 1000 ly. Could such an axion pass through the event horizon of the above black hole? If so, is there an [axion wavelength]:[Schwarzschild radius] ratio where the axion could not cross the event horizon? My guess is that as the [axion wavelength]:[Schwarzschild radius] ratio approaches infinity, the probability of such an axion falling into a black hole approaches 0. Or maybe think of it like how a long wavelength photon (radio wave) would interact with a black hole.

@trucid2

10 ай бұрын

I don't think we know since we don't have a theory of quantum gravity.

@alansnyder8448

10 ай бұрын

@@Crushnaut I don't know if this is the right way to think about it, which is why I ask the question, but it seems like the reverse of Hawking's Radiation. There Hawking did a quick hack of QM and GM to show that things can leave a black hole, here it seems like the reverse with a wavelength bigger than a blackhole event horizon collapsing into it. But then if you add QM superfluidity to it, does it act in some way to pin that Axion Dark Matter to the black hole, which might explain more cleanly why galaxies have black holes at their center. And then I wonder if it has implications for two galaxies colliding the other black holes more easily find each other than with just straight Newtonian or General Relativity. (I'm clearly stretching with the last paragraph, but thought would throw it out there)

@Paul-rs4gd

10 ай бұрын

This is a very interesting point. Doesn't quantum tunneling kick-in at around the wavelength of the 'particle' ? Perhaps axionic dark matter can just 'tunnel' through/past the black hole.

@nagualdesign

10 ай бұрын

​@@alansnyder8448 I may be mistaken but I don't think that Hawking radiation implies anything leaving a black hole. As I understand it, virtual particle-antiparticle pairs form everywhere, and when they form _just outside_ a black hole with one falling in and the other escaping you get matter radiating outwards and matter-antimatter annihilation within the black hole. Having said that, I do wonder what happens to the energy released by these annihilations. Since mass and energy are equivalent I don't see how a black hole would eventually evaporate. The infalling virtual particles would only increase the total energy. My guess is that I've misunderstood particle-antiparticle annihilation, and essentially a positive plus a negative equals zero rather than a large release of energy. 🤷

It surrounds us and penetrates us; it binds the galaxy together.

@pbsspacetime

10 ай бұрын

the physics is strong with this one

@mikeoxmall69420

10 ай бұрын

*penetrates us?* _😳_

I find the debate between dark matter and modified gravity fascinating.

@nulledabyss2230

10 ай бұрын

Especially since it's not so black and white, since both have their own cases where they apply the best, it seems the answer is somewhere in the middle, or perhaps both are true in their own cases. Will be really interesting to see in the future.

@Hecarim420

10 ай бұрын

And both things might be "a case" depend on situation or rather neither of them ¯\_(ツ)_/¯ Edit matter of perspective (and a lot of statistic)👀ツ

@svladcjelli4236

10 ай бұрын

I think it's mostly a repulsive force of empty space that we have not taken properly into account.

@Nethershaw

10 ай бұрын

There isn't much of a debate from the MOND ideas. They fail in regimes that are well-understood, so they have to get out of their own way first.

@GordonBrevity

10 ай бұрын

There just seems no way it's modified gravity.

Thanks for such a great video! When you got to the explanation of dark matter as a superfluid my mind was blown. You guys do such a great job of opening my mind to new concepts, and you deserve major props for the unapologetically technical discussion.

You make physics interesting

@TheArtofFugue

10 ай бұрын

Physics is interesting regardless.

@ashnikchauhan9103

10 ай бұрын

@@TheArtofFugue yes sir, I was casually offended to read such a comment. Thank you to people like you who recognise and give reverence where it's due. (@PakoRakanyane I am kidding of course, glad that you are enjoying and learning physics)

Your videos are on are strange border between simple enough to understand as someone with little scientific knowledge, and advanced enough to discuss complex things like string theory or quantum mechanics. Your work is very interesting and absolutely awesome. Thank you Matt!

Excellent video, Matt and team! This is an exciting time in science!

This may be one of your best epis9des ever. Not just the subject matter (which is amazing) but also the overall delivery / production.

This was a really satisfying video! The buildup from the last few episodes really paid off, great job!

First time I ever immediately re-watch a Spacetime video, in many years! Fascinating! I love this theory, it's so beautiful!

Really fascinating from PBS Space Time as per usual.

This episode is awesome! The topic, the animations and the explanation - superb! Thank you guys.

Another great show Matt , most of the subjects are way above my pay grade but they are fascinating & at least I'm getting some of it . I love your live streams , keep on Keeping on. PEACE and LOVE to EVERYONE.

Thank you for finally getting to this episode!!! I've been hoping for it for a while! Are there any studies on if axionic dark matter could explain structures like the bullet cluster?

Fantastic video, as always! Superb explanations here!

Wow perfect timing! I just saw an article on this and was hoping to find a more in depth explanation. Now I don't have to search

Love your episodes, I always learn so much cool stuff here!

I often feel as a weakly interacting massive particle as well

Great job! I actually followed this quite well, and makes sense to me! At least it sounds as though fuzzy dark matter makes predictions that can be tested.

Yet another excellent and thought provoking video! Looking forward to the follow up! 👍👍

Lots of videos on dark matter these days.. This spacetime episode is the most complete and clear content so far!

great topic

Okay, super fluidic dark matter is an awesome concept. That said, I'm curious about two things. 1) What do these lambda-cdm simulations look like, as in how are they performed and what is the resolution of them, if that's even the right term to use? 2) Now that we've gone over QCD is some detail, could we get a more in-depth explanation of how Axions emerge as a solution to the strong CP problem?

Love it when my phone pings with another PBS-ST video

I was amazed from start to end! If this theory is proven correct, it would be an incredible way to see our universe! Wavelenghts so large that emcopasses entire galaxies! And I'm also happy that I could follow up the entire video, without getting lost along it... being able to undestand it all is great!

Question: I had never heard of superfluidity being related to De Broglie wavelength. Does anyone have a mainstream ressource on that topic? A Spacetime episode or good explanation would be perfect. Thanks to any helper! 😊

What are the proposed characteristics of Axions (spin, charge, etc?) and how do they relate to QCD?

Fantastic ending as always. I had no idea de Broglie wavelength could lengthen that much with reduced mass. 🤯 Its like an invisible 3D spread of fuzzy universe-scaffolding.

To Matt and the Space Time team: you all are the best!! Would love to see an episode on Wolfram Physics 😃 With that, keep doin’ what you’re doin’!

One thing not mentioned here is where they might come from. An interaction that happened in the early universe that might have produced such incredibly large numbers of axions!

@JohnDlugosz

10 ай бұрын

Yes, and specifically produced _ultra cold_ axions. The axion field starts out in a random state after cosmic inflation. As the universe expands and cools, this field begins to oscillate, and these oscillations produce a population of axions. Due to the nature of this process (that would make a good Spacetime episode), they would have very low momentum, making them ultra-cold. Look up "misalignment mechanism" for more information.

@hoon_sol

10 ай бұрын

Dark matter is subhydrogen; it's an electron bound to a proton at a lower state than what is considered the ground state of hydrogen. Also, there's no such thing as "the early universe"; the Big Bang never happened, the universe is eternal.

@DrDeuteron

10 ай бұрын

The source of axions is the scalar product of the electric and magnetic fields….a pseudo scalar field that would have disturbed Maxwell, or anyone before 1957.

I just had a stunning realization. When I watch these episodes when I'm either tired or distracted, I can't fully take it in and I know I'll need to watch it again to try to comprehend it. And my realization is that when I watch when I'm alert and paying full attention, the result is no different.

@nagualdesign

10 ай бұрын

😂

@EnglishMike

10 ай бұрын

This episode was was more comprehensible than some of the others. How do I know? I understood it first time around!

All 100% in sync from Oz. Great Episode. The large wavelength consequence makes perfect sense. Its like an idea that been staring at us for a long time but not seen till now. Great episode, thanks.

Thanks, the visualisations were very explanatory.

I find the "weakly" in WIMP to be ambiguous. Does that mean that it interacts via the weak nuclear force? Or just that all of its interactions are weak?

@garethdean6382

10 ай бұрын

That all interactions of any kind are weak. Generally even the weak force is left out of dark matter's description as this can have very curious effects in relation to things like stars.

Updooting for the algorithm!

Amazing Concept! thanks for sharing it!

Always excited for some space time

I think I actually understood a word or two here and there. Thank you.

"rest assured, dark matter will keep doing good work" is such a profound & reassuring way to end the video

Great video, I enjoy alternatives to the current ideas.

Your description of the de broglie wavelength helped me to understand how particles become waves and even quantum fields

Something I've always wondered about with axion dark matter is how the axions are supposed to get gravitationally captured. It sounds like they're way lighter than even neutrinos, and neutrinos buzz around at very nearly the speed of light, so shouldn't axions go flying off at near light speed with even the lightest push from whatever created them?

@imeprezime1285

10 ай бұрын

Good point. But we don't know what created them. Some suggest there is undiscovered superweak force on microscale with different kind of coupling. Gravity coupling stays the same therefore...

@garethdean6382

10 ай бұрын

The trick here is that the axions would be 'ultra-cold' with very, very low energy. Thus making their velocities far less than those of neutrinos. The specific process that would create these particles ONLY in such low energies is a 'misalignment mechanism' that really could use a spacetime episode by itself to explain.

Whenever I hear about the difficulties of detecting dark matter I am reminded of something Mr. Spock said: Sensors only detect what they are designed to detect.

@alastorgdl

10 ай бұрын

You should be reminded of something FAR MORE OBVIOUS: atheists laugh at imaginary friend (God) but are delighted and faithful at imaginary matter and energy How is that called? HYPOCRISY

@NeovanGoth

10 ай бұрын

⁠@@alastorgdlObvious is primarily your incapability of differentiating between myths made up by people who didn't knew better, and scientific theories based on actual observations and rigid mathematical models.

@alastorgdl

10 ай бұрын

@@NeovanGoth If BigBangTheory is so based on actual observations, why Dr Joel Leja, who is NOT some random delusional scientism idiot from KZread, called latest data from JWST "Universe Breakers"? Because you scientism adepts are so alienated by your "theory", when it's shown as pure rubbish by latest data, you feel like your universe breaks You live in a cult and you don't even know it

Absolutely beautiful theory. Totally bends my preconception of what a particle can be. I am curious if interference pattens could be used to explain the distance between stars during formation.

This has to be one of the more interesting episodes of recent time!

My big obstacle to accepting Axions as the primary form of Cold Dark Matter is that I don't see a mechanism by which they can be created and not have extremely relativistic velocities, which makes them Hot Dark Matter, and unable to be bound to a galaxy. If someone has a plausible scenario as to how 10^98 axions (number required if they are 10^-20 eV each) could have been created cool enough to be bound to the Milky Way, I'd appreciate it if you could tell me.

@Crushnaut

10 ай бұрын

In invoke the Anthropic principle. ... lol

@jamesmnguyen

10 ай бұрын

​@@Crushnaut Anthropic principle solves everything.

@kindlin

10 ай бұрын

I mean...... there is no inherent 'direction' to the big bang, right? So they would all just kind of coagulate in place, like all of the hydrogen and everything else. It's the non-interactivity of the particles that allows the tinniest of fluctuations to have the outsized affect of collapsing everything into galactic filaments.

@JayCross

10 ай бұрын

@@kindlin Neutrinos have a mass near 1 eV, and are generally always relativistic, because they are also created with energies well in excess of their rest mass. If the mass of an Axion is 10^-20 eV there shouldn't be any process that creates them with little enough energy to slow down enough to be captured into a BEC.

@kindlin

10 ай бұрын

@@JayCross I never thought of neutrinos as fast _because_ of their small size, but I guess that if you need to turn literally any amount of energy into a neutrino, it's velocity is going to be huge. And if axions are even smaller..... Well, we know that photons don't get too caught up around galactic sources of mass, but maybe that insty bitsy bit of mass it does have is just enough to keep them stable around other large sources. Here's a wild idea, maybe they aren't stable near gravitational sources, but they are stable near black holes, for.... reasons. Something to do with their de Brogli wavelength being so large it encompasses the black hold, preventing the axion from leaving, even as it can't fall in.

If axions had such low masses, wouldn't existing particle accelerators create loads of them ? Shouldn't that show up as missing mass/momentum in detectable particles ?

@lhybrideur

10 ай бұрын

If their mass is so small and they barely interact with the rest of the matter, the total mass created who probably be negligible wrt the uncertainty on missing mass

@kylebowles9820

10 ай бұрын

Something with an extremely low mass and long wavelength would have trouble interacting with the relatively tiny detectors or carry away enough energy to notice (note the difference in the energy of an axion vs the LHC beam; so many orders of magnitude!)

@DrDeuteron

10 ай бұрын

@@lhybrideurthe problem is the coupling is so weak. I thinks it’s an angle,and theorist are conceded that it has no reason to be small. Too much fine tuning.

@Paul-rs4gd

10 ай бұрын

@@kylebowles9820 So, could we need lower energy collisions and experiments to look for dark matter ? I know that some experiments with muons showed very tiny discrepancies between theory and practice - that seems promising.

@garethdean6382

10 ай бұрын

There's a few issues. Mainly, the coupling between axions and regular matter is likely low, meaning that few will be produced at any energy, high or low. We already see plenty of 'missing' energy or momentum in collisions; they're very messy and energetic things and often almost impossible to balance perfectly. Some particles (like neutrinos) aren't detected, or pass through detectors or miss them. Often we need to look at a lot of collisions to see what on average is missing and what particle might explain that.

It’s cool you’ve done this video now because I recently read a paper on a dark matter detector and this sort of stuff

Excellent video, keep the hard work.

Is there a limit for how much dark matter can overlap with more dark matter? Or could blackholes form suddenly out of "nothing", like rogue waves in the ocean?

@garethdean6382

10 ай бұрын

Once you get past a certain density (Which depends on the volume involved) a black hole will form. While the value's very high for small volumes, black holes like those in the Andromeda galaxy have a value comparable to water. Enough mass in a space will simply distort said space till it collapses in on itself.

Are there any good reasons why 'dark matter' is not just a lot of neutrinos? They don't weigh a lot, but there should be an enormous amount of them

@fluffysheap

10 ай бұрын

Neutrinos are too "hot" - they move too fast and would escape from galaxies. So they don't really match the observations.

@andrews3271

10 ай бұрын

probably because we can detect neutrinos so we probably know about how much mass they would account for

@fkarg10

10 ай бұрын

@@fluffysheap would they really escape though? Galaxies are large and massive, so there should be enough time for them to turn around

@fkarg10

10 ай бұрын

@@andrews3271 yeah we can detect some and roughly know their weight. I don't see why we need to invent crazy new particles when we have one that might fit the bill? Or well, if it actually doesn't, I'd like to understand why not

@thezipcreator

10 ай бұрын

I think there's just not enough of them to account for all dark matter, although they do probably contribute some amount of dark matter.

Very interesting. Thanks, Matt ❤ I like that there are certain fundamental patterns of energy/matter behavior in the universe that operate at all levels of organization and at all scales. Thanks to which you can extrapolate and predict. One of the most interesting patterns of behavior, in my opinion, is wave dynamics. After all, the ancient metaphors about the endless primordial ocean from whose waves everything emerges are confirmed 🤓

Really excited about the big astrophysics announcement tomorrow. Best case, this episode needs a new ending!

The "superfluid" idea for whatever "dark matter" is works out to be rather a good one. Sabine (the wonderful) did a video a few weeks ago on a similar approach, though I don't think Axions were specified, but that didn't seem to matter. IIRC, where there was low "dark matter" density, there was no superfluid effect, hence what looks like "dark energy" instead.

"they're actually predicted by string theory" that's not a good argument. String theory isn't even a theory

10:00 This is so crazy. I've always liked what Dr. Wilczek has to say about his discovery - axions - almost as much as I respect him for his humility. But I've never understood the relationship between these models in this frame of reference. In fact, I've never seen nor heard the qualities of axions described in the way you're doing it. (Kudos, btw!) It's crazy to think that all of things I've seen and heard ,specifically regarding the discovery of a potential axion, could lead to a more accurate understanding of what exactly is going on out there (and in every cube of one hundred meters, all around us).

This was an interesting video. It's nice to learn of the possible properties and mechanics of dark matter.

guys, stop doing first. it's lame

@danielalexandre89

10 ай бұрын

1th

Amazing video as always!

Tremendously well explained and entertaining presentation. Thank you.

man, i really appreciate this content

I keep coming back to this video cause the idea is so beautiful and sensible to me. It feels like dark matter could be space itself, a cosmic superfluid ocean

@paulthomas963

Ай бұрын

We already have a quantum field and fluctuations. Those are established facts. Those rotating dipoles are not dark matter, they interact constantly.

Щиро вдячний за цікаве пояснення!

Great episode!

What a nice episode!

Love listening to you the best you express bravo

thank you for this revelation! 😲

Great! Pretty clear and incredibly interesting 😊😊😊...

Fascinating! I always wonder if after a few more decades of further experimentation we'll learn that the current various interpretations of dark energy/dark matter are the phlogiston of our time, and String Theory is equivalent of the Plum Pudding model.

@neohermitist

10 ай бұрын

Sorta like a dog chasing a squirrel then it starts barking up the wrong tree and can't seem to let go of it.

Best Science Channel on KZread! Thank you. Seems I like my Dark Matter Fuzzy rather than Cold. :)

Thank you for the video.

Yes!! Now that’s a fun model and an unparalleled description. Elite status teaching skills here! Wow!

Wow! I understood almost nothing of this, but still enjoyed the presentation. Maybe someday.

I’m going to need to rewatch this episode with greater focus.

the last word was "spacetime"! wow! I like this :)

Thanks! Great video

Fascinating stuff!🔭🌌☄

These episodes always help me sleep

I love this channel so much

Can't wait to learn more from future interferometric observations into these "fuzzy" effects of axionic dark matter!

What a week ! JWST detecting CH3+, IceCube results for high-energy neutrinos and NANOGrav's evidence for the gravitational wave background. I'm looking forward to learning more details about all those great news (or at least some of them) !

Great explanation. Are the surveys you mentioned related to the Webb telescope? And nice, maybe string theory's legacy can be salvaged

Another video about magic! Nice!

It’s very soothing to imagine galaxies all taking a superfluid bath together.

I understand like 2% of all this and I love it

Excellent!!

Please cite the papers you mention/get the information from in the description, thx!

Thanks for preparing us for today’s major astrophysics announcement!

Lovely video. Now all you have to do is explain the non-trivial vacuum structure of QCD, strong CP violation and PQ symmetry.