Dark matter. Or what? 

There's something strangely refreshing about listening to a presentation unencumbered by fanatical hyperbole and sensationalism Excellent video!

The fact that English is not her first language makes her presentations even more impressive. Clearly an extremely bright and capable woman.

Finally I found a serious scientist on youtube. Thank's Sabine!

Thank you Sabine, your videos are my favorite ones about physics. I have a physics degree but could not continue to a doctoral research. I read as much as I can about theoretical physics, and I am also surprised about how much damage is being done by "popular videos, books " etc. to serious physics thinking. Thank you for maintaining the rigor here on RU-vid (as much as possible.)

Excellent video; very clear and balanced presentation, no hype, just pure facts what we know at the moment. Definitely the best science video in RU-vid what I have come across. I really hope you have time and energy to do these more. Thank you

I just love that physicists take time to produce these videos to help us all understand what is going on. Thank you Sabine Hossenfelder et all!

You're good at this, well done. Graphics support the script. That's what is needed. Not a production. You are building a reputation in this medium for telling it as it is, no bullshit.

I love your voice -- there's a cutting clarity and precision in it that communicates difficult concepts effectively. There are a number of RU-vidrs blessed with wonderful voices. You're one of them :)

9:30 "now here is where it gets interesting". It was pretty damn interesting up to that point.

Sabine: "now of course we don't have dark matter in bags" (looks off camera, in visible annoyance at not having dark matter in bags)

Possibly the single best discussion of the topic I've run across. Looking forward to 'the next time'.

please dont ever stop explaining physics

What a clear and highly distinctive presentation on the Dark Matter. Thanks you very much Professor Sabin Hossenfelder.

You're doing amazing work!- Not only as a physicist but as a science communicator.

This is the clearest explanation of DM 's properties I have ever heard.

I love your videos. Been watching physics videos for years, and you are so precise, to the point, and efficient. You're also so very intuitive.

Excellent video ! No hype, no super-sensational, just facts and a clear presentation of where we stand with this cosmological "mystery". Thank you !

this might be the most depressing, but one of the most intriguing physics channel on YT.

Really good explanation as always, Sabine. As you know I’ve written a lot about dark matter and yet I learned a lot.

One of my favourite explanation or rather clarification on DM...well done Professor!!

Godammit woman, I just love your presentation style and sensibility ("It just doesn't make any sense!") Indeed, science has much gooblygook and you are like the cleaning fluid that clears the way!

Great video. Balanced and unbiased (or at least that how it appears) like science is supposed to be. Just pros and cons of competing ideas.

- Damn it! I pride my self in being knowledgable & on the cutting edge of astro physics & then she comes around & always floors me. I dont like intellectual boxing with her. She makes me feel like a grade school student. - But I get up & lick my wounds & wait for her next presentation. "Keep up the good work!" - A devoted fan

Honestly, your videos bring a lot of light for the rest of us. Scientist of social sciences or other fields. Thank you for the big work it takes to produce videos for the sake of clarity.

Good to see an intelligent scientist being honest instead of pretending she knows things that she doesn't!

This channel is fascinating she is very thorough in her description and explanation of complex concepts

Thank you very much for your cool & compact explanations putting the actual discussion about cosmology together! What is the status, the background, the pitfalls and uncertainties - like it very much!

I can't overstate how valuable you are to my family. Please continue doing what you do!

"Now of course we don't have dark matter in bags..." 😆

Excellent video and very worthwhile for busy people.

I love this lady and I love how more and more polished her videos got over time.

It is so nice to hear someone point out that the emperor is wearing no clothes. I am more impressed by you with every video I watch. Kudos to you for putting the integrity back into science.

Thanks for sharing your knowledge in such a simple way.

Thank you for this - as you say - it is so hard to find any kind of comparison between MoND and Dark Matter. Appreciated.

These videos are amazing! Thank you for making these subjects so accessible!

WOW!! I love this video. And you had me with the Bullet Cluster. I kept hearing that it ruled out Modified Gravity, but I didn't see how. Thank you for explaining both sides so clearly. Plus, I loved the intense close-ups. The juxtaposition of your matter-of-fact tone, and the intensity you bring to your topics was wonderful!! I would love to see you crack a smile once in a while, but that would be like breaking character. You are so awesome!! Don't change a thing. Keep on doing what you're doing. Thank you!!!

The standard Einstein-Hilbert action is simple and describes gravitation well, but it is not a conformal theory. Conformal invariance requires that you replace the EH action with something similar to the one proposed by Mannheim and Kazanas in 1989. That action reproduces the predictions of EH but also hints at a purely geometrical explanation for dark matter. Hossenfelder's video brilliantly outlines the problems associated with both particle dark matter and modified gravity, and I look forward to her future talks. Hopefully she will include her thoughts on the ongoing failure of costly experiments to detect dark matter in the laboratory.

A wonderful educator, explainer and presenter. Fascinating stuff even to those of us who struggle to keep up.

1:05 maybe dark matter interacts bi-weekly and we've been checking every other week and that's why we haven't been able to detect it.

Love your videos which are full of honesty and common sense. This is not always available from the science community.

Thanks for the clear, calm exposition. As a biologist I cannot judge whether your preferred interpretation is better than the more widely publicised dark matter explanations but what I will say is that listening to physicists talking about dark matter reminds me of invented explanations like the ether to explain cosmic radiation and phlogiston to explain combustion. Based on those two earlier cover-ups for ignorance I am suspicious of dark matter and think it quite possible it is a place holder for something we don't understand about gravity. So I am sympathetic to your direction of thought. I like your straightforward delivery much better than the breathless, over-hyped PBS Eons deliveries. Look forward to more.

Thanks for the awesome explanation. Your wit and dry and subtle humour is exemplary. Beautiful way to teach science.

Very informative and I really like listening to your accent

1. I'm trolled senseless by people saying "velocity" when they mean "speed". 2. This is a nitpick. Great work and great videos!

Love the Germans! Always straight to the point.

I love her, she brings a level above the common popular science type videos in you tube while not getting so technical so to be completely lost without the background.

It should be called fudged matter to reflect the state of the models.

Love listening to her explanations, but the very best part of this one is she started with "we don't know". Far and away the most important words in any hypothesis and even theories. There is nothing wrong with admiting "we don't know".

Wow! This is the best dark matter video I've seen so far.

Well explained.a real teacher of physics. A gifted scholar with beauty and brainy..much love to hear you talking on complex subject.tq.

I get the feeling that we have it all wrong. I don't think the Universe is expanding, Don't think there is any dark matter...and I believe the universe is infinite both in the past and future. I believe that we are interpreting the red shift wrong, or we don't quite understand gravity yet. The real gut punching truth is we don't really know squat yet.

i am a biochemist but each time i listen to you i wish i did physics. i love you too much

Such concentration to detail! Wonderful!

I love your videos. I love that you explain misconceptions. I'm a fan.

I disagree with the asssertion that outliers do not disprove theories. In fact, that's the only kind of thing that disproves theories. If your theory can't explain the outlier, then it's not correct. Now, saying that dark matter can't explain the outlier either is a valid point.

Compared to some of your recent videos, it's very inspiring to see how your presentation skills have progressed so well. Bravo!

Very good explanation, as usually. TX a lot!

You are such a breath of fresh air! These TV scientists who sensationalize and politicize everything.

I really like your videos, keep up the good work :)

I learn a lot from your videos.. one of the best physics channel in RU-vid. All facts, nothing extra.

Thank you Sabrine for your honest insights into these physics questions.

I appreciate the view that Dark Matter may be an incomplete understanding as opposed to a correct theory. I am aware that if we just pretend like there's a bunch of mass there, but we just can't see it, the math works out. It's only a feeling, but something tells me the answer is something far more mysterious; something we haven't even thought of yet. It's just a feeling, though.

I love this woman! Wow! What an intellect, hyper focused, low affect when she's obviously passionate about what she's explaining. Ein gutes und brillantes deutsches Mädchen. She is in her own way, f***ing hilarious! I think knowingly and purposefully. Either way -- one incredible human! Copy her genes!

i wish sabine was my teacher .. i feel i could have learned a lot at the right time .. thank you for doing this .. explaining complexity like relevant story ..

This is really great, thanks H!

Well done the zoom and more intense lighting at 1:26 ! Yes, gentlemen, eyes are blue ! ;)

Love the way you say "Einstein".

Sabine, As a professor of Renaissance and Baroque Poetics and Rhetoric, I did not expect to find myself obsessively watching a RU-vid channel presenting intellectually substantive lectures on quantum physics, the limitations of particle physics, dark matter, and modified gravitational force. Fortunately, I have *some* background in astronomy, calculus, and differential equations, so I actually *do* find your serious, not-condescending lectures intriguing… I must say: proposing an unobserved quantity/force/particle (dark matter) *so that* the equations we currently have to explain how the universe functions actually “work” strikes me as questionable. “Easy fix” indeed. I was able to follow your lecture well until you began talking about the problems with modified gravity as explanation; at that point, had this been a classroom, i’d have raised my hand and asked you to re-explain certain points more slowly… Overall, however, I do love seeing a brilliant mind pragmatically explaining her subject. Bravo!

I'm in love with your channel.

So German. So clinically straight and to the point. Lovit

"Fritz Zwicky and the virial theorem" would be a good Harry Pottersque title of a novel 😂

Respected Sabine Hossenfelder thanks for explaining physics and math in such beautiful way

“Or what” is more like it at the moment. Cool how your outfit matches the subject matter. Love your dark and dry sense of humor, too. “Of course we don’t have dark matter in bags.” 😂🤪😍

Exceptionally clear description for such a short video, and speaking as an astrophysicist and author of a book on dark matter and dark energy. One thing not mentioned is that the excess acceleration observed in galaxies and clusters cuts in at ~ c*H ~ c / age. where c is the speed of light, H is the Hubble expansion parameter, age is the age of the universe. This is quite a coincidence or else supportive of modified or emergent gravity.

Dark matter is like a last minute patch from the developer to allow for structure formation ;)

Dear Sabine, Your videos are kickass! Thank you for your channel. I am a simpleton armchair science nerd that enjoys learning about physics, cosmology and quantum mechanics for fun as these are my favorite things to think about. My question is this: So is it fair to say that the evidence for Dark Matter is circumstantial in practice? I have had personal problems accepting dark matter as a factual concept although I do realize that circumstantial evidence is real and practiced everyday as for example; one does not need to actually know its snowing outside if a person enters your home with snow on their clothing, one can reasonably make the assumption that it snowing outside. I do realize this is an oversimplification compared to dark matter but is it possible that scientists measurements are off or that we have a basic lack of understanding in regards to the fundamentals of the Big Bang and cosmology in general that could account for the circumstantial evidence we point to in creating Dark Matter as a “fix”? I just have never been comfortable with dark matter and I feel the concept is off base and incorrect in some major way. Of course I am not a scientist that studies this, and am merely an idiot that lacks the brain power to understand all the science, however I submit my 2 cents here nonetheless.

Very coherent presentation. Thanks! and... finally someone correctly pronounces Albert Einsteins name!!!

Somehow it feels like at least half of all scientists are constantly busy with making a mockery of scientific work, by falling into sensationalism, esoterics or straigth religiousness - so this voice of clarity is as wonderfull as it is deeply necessary.

Hi Sabine, What are your thoughts on quantized inertia as an alternative explanation?

Clear, concise, and to the point!

0:21 That is how we know a true German Great and informative video

Hossenfelder has had it with scientific misinformation and disinformation. She is on a mission to set the record straight! I love how accurate and informative your videos are. Thank you for producing this high-quality content!

as far as I'm aware, it's rather hard to build a theory of modified gravity that doesn't include a scalar mode, and those are hard to hide

Please provide transitions between different sections of the video. You can try some fading transitions, titles for that section, and possibly some music to make the videos last mundane. This is just a suggestion, thank you for providing your vast knowledge.

Yes.... " We do not even know if it exist!!! " Funny many science papers and documentaries assumes it exist, despite stating they dont know much about this mysterious matter!

You make it so clear so we can under stand it thank you so much

The 'Cosmological Constant' was a very simple explanation as well when it was first proposed, but that did not make it the correct explanation.

Such clarity and conciseness! Thank you so much!

I just wonder -- if the galaxies are thousands of light years across how do we compensate for what we see? Wouldn't the backside of the galaxy appear they way it was thousands of years ago as compared to the parts of the galaxy that is closer to us?

0:43 Not sure what but I laughed so hard at your expression ... almost like you were a bit sentimentally dejected that we "don't have dark matter in bags" haha.

I love getting the straight dope from Sabine!!

I was all on board in the beginning but now, years later, i am strongly considering that their might be a possibility we haven't considered yet. *Like admitting we might not fully understand the manner in which massive clusters (such as galaxies) or clusters of galaxies. I have heard that there is this science and behavior with the void of space, between the galaxy, and we've been learning a lot more about "the vacuum of space" but its not a true vacuum, it has a positive force *or that it's behavior is a bit different than we initially thought. Like how black holes 🕳️ and the void of normal space is a different balance then we first thought. And it really seems like a wonderful depth to our scientific understanding of space, and how it behaves, there are very indepth videos about it. I just love how Sabina tells it like it is and leaves things open to discussion. Where I've felt like Every other scientist is NOT open to even talk about (well what if? And still question, and stay open enough to do sound science) its like sone people are so set on dark matter that they are willing to rule out actual scientific findings because they are too focused on trying to "find dark matter" but a true scientific approach is the exact way Sabina did here in this video. You just admit you dont know, be open to many hypothetical possibilities which could have led to that outcome occuring. BUT some scientists are set on exactly why its occuring, which is forcing a "set answer" to that problem. Instead of even possibly entertaining theoretically *is their a chance any other little factor is wrong? Because to me, nothing is wrong with that. A good scientists would go back, consider our all of our equations values, consider that: even if our equations have worked so far until here, and if it maybe worked here (instead of forcing the predetermined outcome that it will work for everywhere so there has to be____), could it maybe slightly different for (insert value of said factor, and maybe even slightly different value for the next said factors value) when it comes to understanding immense things such as a entire Galaxy and how it fully interacts with space around it *then clusters of galaxies too seem would have an even more different interaction with space around them and them interacting with themselves... (If that makes sense?) Im just hypothesizing here so im totally willing to me incorrect. [i don't know??] 👍🏻

I've always thought if >90% of the observable evidence doesn't fit the theory, then the theory must be wrong. Perhaps we are doing it wrong

Very simple to understand, thank you. In my experiments, I just saw it as negative energy.

You are a grrat communicator for physics, e.g., better than Tyson amd a little better than Brian Greene. Mu backround is being the inventor of the IBM Watson Computer. I have a Ph.D. in Rlectrical Engineering where Richatd P. Feynman was my 1st cousin. Please keep making these highly infotmative videos! Thank you, Andrew S. Beoler at IBM Research

Simple and just beautiful. Thanks Dr. Hossenfelder

Intelligence is the new beauty/sexiness. I'm in love !

She is the greatest debunker of trendy theories.

Pretty nice. Almost your fan. So, there are 10 Einstein equations that predict the movement but they can't accurately do so. Almost, but no. That's no problem. Still, isn't it time to begin popularizating the fact that, as Newton, Einstein was wrong or incomplete? He made a great job trying to explain most of observations, but I don't like the kind of mistification, idolization, mass media has done with his image and theory. They lie.

excellent video and presentation Sabine. Thank you very much.