Bad news for dark matter: This data doesn't fit at all

[@amaze2708]

Flip flopping is good. It means you’re not married to an idea, you let new information, new data, new ideas influence your “best guess.” This is true science. Nothing is sacred.

[@azmard4865]

While it is important to have solid principles, I have always found comfort in adjusting my perspectives on things huhuhu

[@mikemondano3624]

I'm glad nothing is sacred because that's exactly what I worship. Nothing really does matter and I am a true know-nothing. _" Das Nichts als das Andere zum Seienden ist der Schleier des Seins."_

[@chazbertino6102]

For science yes, but doing it every 2 seconds in politics is just scummy.

[@azmard4865]

@@chazbertino6102 exactly

[@KyleCypher]

Could it be both? MOND and dark matter? (Just less?) Maybe modified MOND...MMOND if you will. Lol

[@Nick-yz9fd]

Honestly, this channel and Anton Petrov's channel are the best for the latest in science news. I've learned so much over the last couple years. Thank you, Sabine.

[@SolidSiren]

Agreed!

[@scene2much]

They are the perfect opposition of lover and warrior energy.

[@osmosisjones4912]

it's finaly completed: kzbin.info/www/bejne/oIOYfWBmZ9CcfLc

[@Jan96106]

He's just doing the reading on the internet for you. You could do your own reading.

[@ro4eva]

Yeah and they're not mean-spirited if you disagree with them (that I know of).

[@goodspellr1057]

5:04 "Theoretical Physics is keeping us all on our toes" I'd say that it's actually Experimental Physics that is keeping us all on our toes ... as it should. And I say this as a theorist!

[@ProgenitorFoundry]

a "theorist"? that word doesnt mean anything. I can call myself a "theorist" cause i "theorize" about the size of my nutsack when its out of my views. So no, Theoretical Physics is right.

[@owena7434]

They are using pictures that already existed bruv

[@goodspellr1057]

@@ProgenitorFoundry Within the physics community, "Theorist" is shorthand for "Theoretical Physicist". "Experimentalist" is shorthand for "Experimental Physicist".

[@RadicalCaveman]

@@ProgenitorFoundry May the size of your nutsack never have a flat rotation curve!

[@georgkrahl56]

@@goodspellr1057 ; One could also say experimenter. I prefer 'experimentalist' because it is a combination of experimenter and mentalist. My boss is a theoretical physicist and I spend a lot of time to try to read his mind. Standard communication processes do not work.

[@BillySugger1965]

MOND’s fatal flaw is that not all galaxies have the same rotation curves. Some are almost as predicted by GR models. Others are extremely flat. If gravity was wrong, all galaxies would be equally wrong. And they’re not. There must be differences in their composition, and those compositional differences are what we call dark matter. None of the models fit all of the predictions, so we need to look for a better explanation than either DM or MOND.

[@aarionsievo]

I am also pretty sure that observations like the bullet cluster were quite convincing that there must be a considerable amount of dark matter in galaxy clusters. Nevertheless, these new findings are very interesting and I would really like to see a new theory, if DM and MOND were both falsified XD I hope for something like distortions of gravity as a sort of pollution, caused by FTL drives of galactic civilizations!

[@santyclause8034]

The age of stars will determine the mass distribution of atomic density. If that's even a sensible generalisation. This should help consideration that the mass distribution modality of individual galaxies may be heterogeneous. Throw me a cookie.

[@manishm9478]

@@aarionsievohehe been reading a certain sci trilogy?

[@freeofmefree]

We do know some types of dark matter exist. In particular, black holes are a pretty obvious example. But there are plenty of types of matter that don't really emit light and could throw off the rotation curve. I wonder if this kind of thing could partially explain what is going on(along with mond).

[@Zeeraha]

Yes, and I am not sure if the paper featured in this video says if all the measured isolated galaxy show the same lensing effect far away from the galaxy, or this waa discovered only on few samples?

[@bunkerhill4854]

Science is like inverse politics: In science lots of things work, but we don’t know why In politics nothing works and we know why Scary

[@elustran]

I really like it when KZbinrs respect our time. Content like this that is concise and to the point is great, and I also like that Sabine has some longer form content as well.

[@beastmastreakaninjadar6941]

Most of her content has become these quickies recently. She's chasing the algorithm.

[@pensive8552]

"We have alot of evidence for dark matter, which may not exist." I love this statement. I wish we treated all fact finding missions this way - being honest about what we do and don't know.

[@Berend-ov8of]

Be carefull what you ask for. The risk you run is having to be honest about a lot of things you don't even want to consider being honest about. I drop the occasional truth bomb to see how viewers respond, and the results are ugly.

[@Prometheus4096]

It should be "We have a lot of evidence for dark matter, which may or may not be actually real matter." Dark matter is real. We call it matter even though we aren't sure. If it is not matter, then still dark matter is real. It just isn't matter.

[@Berend-ov8of]

@@Prometheus4096 There is something highly confusing about calling something matter that may not be matter. We're not just naming things here.

[@Prometheus4096]

@@Berend-ov8of Of course it is confusing. But these are decade-old terms used by experts in the field to discuss their progress on science. Among themselves. Scientific terms often mean something else, because of historical reasons, than what they logically would mean. You might not know this. But Dr.Hossenfelder does. It was named 'dark matter' because it was expected to be a particle soon discovered. Then it never was. And all methods like MOND that try to fudge the math to match the observations also failed. So either it is a combination of wrong measurements, together with actual dark matter we didn't discover yet, together with an MOND-like adjustment to gravity. Or it is some ground-breaking idea or concept that we haven't even thought of. But we will call it 'dark matter' until we know what it is. Now maybe scientists should have changed the term. Like 'dark gravitation' would be a great term. But that's not what happened. We need a source of gravitation to solve the dark matter problem. And a source of gravitation by definition is called 'matter'. Either every galaxy needs their own version of MOND PLUS our measurements are wrong. Or there is actually a different amount of dark gravitation, caused by matter, in every galaxy.

[@exscape]

@@Prometheus4096 Is that really the case? Maybe in some definition, but not in Wikipedias: "[D]ark matter is a hypothetical form of matter that appears not to interact with light or the electromagnetic field. Dark matter is implied by gravitational effects which cannot be explained by general relativity unless more matter is present than can be seen." By that definition, if MOND is correct, dark matter does not exist.

[@arctic_haze]

I would wait for studies trying to reproduce this result. MOND has problems in both larger and smaller scales than galaxies. I think the solution will be something more complicated and probably surprising

[@SabineHossenfelder]

Yes, I agree with that. But whatever the right answer is, it has to look a lot like MOND in galaxies (and around them)

[@FabioCoatti]

I guess someone is investigating if multiple causes can explain the different behaviors that we see (bullet, rotational speed, etc). I know, the economy of explanation is important, but this back and forth makes me think that more than one factor is at play. Is there some papers on this topic?

[@nevetstrevel4711]

Is it possible to have both?

[@fortusvictus8297]

I still suspect it has to do with changing of what we consider constants. When viewing data that is sometimes 10's of millions of years old, even into billions, if something like the speed of light or any other gravitational measurement we use as a baseline was not the same then it would impact our current observations and measurements in some ways.

[@AquarianSoulTimeTraveler]

​@@SabineHossenfelderI think the most logical Baseline system to represent dark matter is one-dimensional string membranes that have been destroyed by a singularity and ripped and this is all that can escape from the other side of the black hole singularity... this makes a matter in between zero dimensional and one-dimensional... this is the most fundamental stance of modern string theory(by Samoht Sirood)

[@laposgatti3394]

GR may be wrong, but DM is still needed to have large structures, explain observations such as bullet galaxy, the barionic acoustic oscillation signature in the cmb and much more

[@riggsmarkham922]

MOND just seems like a kludge to fit the aesthetic sensibilities of people who want to universe to feel “elegant” - a lot like the cosmological cosntant

[@かみく-p3j]

​@@riggsmarkham922 To me both dark matter and MOND feel like we're trying to make up classical explanations for a deeply quantum system. It seems like its more of a philosophical problem than a theoretical one. Ofc its quite the hurdle to get actual experiments going to test quantum gravity, but that seems like even more reason to focus on it to me. It all just makes me think of what would have happened if, somehow, we barely had ways to test the quantum properties of stuff in the early 1900s - would we have just kept trying to make classical explanations fit more and more contradictory data? Seems like we have a history of doing that even when we do have data lol

[@stummi90]

Maybe it sounds dumb, but I think I don't really understand Dark Matter at all. It feels a bit like this: I have a Den with three Lions I Theorize that one Lion eats 500g food per day I measure that much more food disappears every day than fits to my initial assumption I postulate that there are 27 invisible, unmeasurable lions in my den, to make my first assumption still work out. Is this analogy right?

[@skya6863]

Maybe more like we have incredibly good evidence a lion eats no more than 500g per day

[@aretwodeetoo1181]

Yes, that's correct. You call them dark lions. When pressed you claim in a patronising tone that all zookeepers know that name is a placeholder representing the "missing food" phenomenon. But you don't change the name, instead you keep spreading it in literature aimed at younger and younger readers. You spend the rest of your career inventing math for new unfalsifiable theoretical biology that could explain how these lions bodies might work without interacting with any light. You also sell dark lion insurance. Okok, I might be lying about that last one...

[@_abdul]

Newton: You can't escape Inverse Square Law. Some Physicist : Don't MOND if I do.

[@GreatPhysics]

you can in one less dimension, then it is inverse 1/r law. Or... as we live in three dimensions, take a cylindrical dark matter source. That achieves the dimensional reduction for you.

[@thesenamesaretaken]

​@@GreatPhysicssimply extend the galaxy up and down to infinity, problem solved

[@evangonzalez2245]

Well if you're stacking universes in a higher dimensional plane, ya got your infinite cylinder right there 👍

[@TicTac2]

are there any ideas on why the inverse square law would be wrong? I mean gravity is not the only inverse square law in physics is it

[@richardchapman1592]

Inverse square law has a constant for all space and time. You answer how that may be possible. I'll say it could be otherwise.

[@mnmarkYT]

Love the MOND-o-meter

[@svenfuchs8446]

I have a lot of respect for people who are quick to change their view if new information comes out. I dont understand how some perceive this as having no backbone, its good to question ones own view

[@MichaelWinter-ss6lx]

@svenfuchs8446, they sometimes confusing scientific theory with football teams. This is also newest paradigm in politics.

[@ulrichmeise3658]

Why not, but I think it might be mistaken for the Mondometer, which is of course for measuring the likelyhood of DuPlantis to set a new world record in the Pole Vault...

[@qwertyFUBAR]

Now in addition to the ENSO meter I have MOND meter

[@richardchapman1592]

See the 1st nonmember reply concerning variable speed of light according to distance of photon wave function to inter stellar mass.

[@myfriendscat]

Open-minded, not prone to conformation bias. That's amazingly refreshing!

[@Zombie-lx3sh]

Confirmation bias. It has nothing to do with conforming.

[@connerharte7084]

Not to judge but you sound like a flat earther, take a class. Or prove me wrong if you are an expert

[@eingyi2500]

​@@Zombie-lx3sh im sure conformation bias exists too haha

[@jorgmeltzer9234]

mondieu!

[@Berend-ov8of]

Being open-minded means being aware of the confirmation biases you're prone to. They are always there.

[@douglasstrother6584]

In any discussion of Unified Theories, Gravity, Electromagnetism, and the Strong & Weak Nuclear Forces are taken as the four fundamental forces of nature. The first two are part of our everyday, macroscopic experiences. It's curious that Electromagnetism has been largely excluded from Cosmology. Revisiting the concepts in "Cosmical Electrodynamics" by Alfvén & Fälthammar, and "Physics of the Plasma Universe" by Peratt is in order.

[@mikejfranklin7000]

I had to watch this video 2½ times (I'm 76 and it shows), but I love MOND. I'll become a proper subscriber now.

[@3zdayz]

Would still be really nice if someone would just come up with an entirely different idea. Like magnetism has an effect. In that case the center of the Galaxy can be rotating slower than it should be which means it matches the outside speeds. Your curve isn't actually quite right when I was researching this a few months ago the acceleration curve actually goes up from the center and has a peak towards the center and then flattens out... But then I think there's so much light from the galactic core that it becomes hard to measure what that rotation rate actually is and why it's close to zero

[@Barteks2x]

Look up "emergent gravity" or "entropic gravity"

[@3zdayz]

@@Barteks2x doesn't help with the neglect of magnetism.... And it is emergent... By an effect of particles moving in small random motions will find themselves in space that requires less energy... And the accumulation of those motions will produce an acceleration towards a deeper gravity well.... Where space is less dense; time dilation in a gravity well is the same as moving at the escape velocity from that place in the well... So just like clocks moving at a high speed have cover more space than they would at slower speeds, gravity also increases the amount of space the clock has to cover in a fixed.time. (this is actually a very small amount for something like the earth... But still not zero. Also since light is carried by the space any such curvature is imperceivable by organism or mechanism)

[@ShamusWoosley]

@@3zdayz Overlooking magnetism is only part; where there are magnetic fields there are electrical currents. Yet the vast filamentary web we see in photos running in flows even connecting galaxies are dismissed as "gas." Factor in electrical forces, millions of times more powerful than gravity....no need for "dark" stuff...or black holes to provide the missing element. And don't wait for Anton or Sabine to tell you...too much peer pressure to think outside of the box. Maybe try an electrical engineer...practical people.

[@MichaelWinter-ss6lx]

Its even much more simple. A galaxy is NOT lika a solar system. There are many stars sharing the same orbit, more the further out. Now we have surely solved the three-body-problem. Then we can blame the 3-billion-body-anomaly on the DarkSide and shoot it onto MOND. 🚀🏴‍☠️🎸

[@3zdayz]

@@ShamusWoosley Yes, true :) There's also ferromagnetic properties of stars - since they often have a lot of iron in them, which allows magnetic fields to be induced in them... Electric Universe I guess would be the other place to find such information - but they are just straight out because they don't believe in large massive objects that don't emit light... so it's more a desire to see someone mainstream support such things. (see also 'The Primer Fields' (esp. part 1, 19:42-ish) )

[@Flixerine]

Thanks for the update Sabine. I find it difficult to really understand Dark Matter, so in a way I'm glad, but reality doesn't really care about what I want, so would just be nice to know what is really there. Maybe one day we will know for sure.

[@danielhale1]

Something I love about learning about science is, new information changing our minds is a good thing. Anywhere else it's treated as weakness in character -- you should supposedly resist changing your mind no matter the forces against you, no matter the price, and to yield reveals a devastating character flaw. But in science, we really do just care about what the data and best models tell us, and it's all up for grabs when new high-quality information comes out. Major shakeups are not automatically trusted -- they have to be vetted -- but they're not an enemy to be defeated. Really the worst enemy of your ideas should be yourself; your data's first earnest refute attempts should come from you. IMO that's so much more healthy.

[@markgoodman001]

Thank you! I find any data challenging dark matter particularly compelling. The possibility of a cosmic web comprised of confined, interacting plasma filaments at cosmic scales, rather than dark matter, deserves further exploration. The filamentary structure observed in the cosmic web aligns remarkably well with predictions of large-scale Birkeland currents in a magnetized plasma universe. Galaxy formation within the densest regions of these currents, analogous to z-pinches, would be a fascinating avenue for investigation. Moreover, the electromagnetic forces associated with Birkeland currents could potentially account for the gravitational effects currently attributed to dark matter. What do you think @Sabine Hossenfielder?

[@michaelleue7594]

I feel like both of these theories have so many points against them that rooting for one or the other at this point is like debating whether it's going to be Zaire or Canada that wins the next World Cup. Once we figure out the real answer, both of these are going to sound so obviously insane.

[@williamschlosser]

Try plasma cosmology, the only self-contained physical theory of the universe.

[@sinisalazarek4568]

I always had a worry (maybe wrongly), that the problem is not in missing mass or that GR is wrong, but in our inability to actually solve GR field equations properly for a complex system such as a galaxy. When I say properly, I mean actually do the nonlinear partial differential field equations with all the bells, tensors and whistles for all the masses etc in the galaxy. Maybe we'll never have computers with enough memory and processing power to do it. But just wondering if by making assumptions (i.e. these terms are not important in this case, this doesn't/shouldn't influence that.. etc) and simplifying calculations to something which we can actually calculate, that we don't see the full picture. In other words, that there wouldn't be any discrepancy between observation and calculation, if we could actually do the GR as intended by field equations.

[@greengoblin9567]

That's the thing. We have two dark entities: dark matter and dark energy. There might be a third dark entity making the extended flat rotation curves possible. The real explanation is that there is definitely a problem with the dark entities that supposedly make up the majority of the universe. It needs to be revised.

[@williamschlosser]

@@greengoblin9567 Or tossed.

[@codetoil]

Unfortunately, according to "Gravitomagnetism and galaxy rotation curves: a cautionary tale", the effects of full GR without dark matter isn't enough to effect the predictions, given how slow compared to the speed of light the stars far away are moving.

[@sinisalazarek4568]

@@codetoil I'm not in a position to evaluate either claim as I'm not a physicist, my interest is purely as an amateur. But for every paper claiming one thing, there is a paper claiming another, so I'm not prepared to take sides just yet. The paper you reference seems to take a beef with one single author and his methodology, but there are various approaches and I don't see them addressed there. From what I gathered so far, Tully-Fisher relation is still very problematic for lambdaCDM. If most of the mass is not visible, then how come only the visible barionic matter seems to be enough for rotational velocity? Why I wrote that I think GR is just fine and it's the math that's the problem, is along the lines of Kerr and his recent paper about singularities. I feel a lot of "problems" arise from the fact that the common approach to cosmological calculations is to first reduce everything to extremely simplified sets and then see what happens. While I understand why it's done, and often times it works, I don't think it works all the time.

[@gracebromfield9070]

Oh definitely keep the Mond-o-meter🙏

[@Thomas-gk42]

Is it available on amazon? We could make a bulk order then.

[@TheDrewjustforyou]

Mon-D-o-M-eter or MonDoMeter Mond or DM and they share the D because it's physics and the scientists (apparently, especially the arm chair scientists of the Internet) need to be reminded that they should share with one another. (Have some damn courtesy to each other you Internet denizens!)

[@majorhumbert676]

Wimpometer works as well

[@kurtiserikson7334]

It should be right next to the dark energy Super Nova Versus cosmic background radiation age of the universe odometer.

[@a.karley4672]

MOND-o-Meter, but done as a punch-bag. Manipulating the local gravitational field so that the ball never comes back to rest in the same position twice, is left as an exercise for any theoretical physicist in the room. An experimentalist would fake it with magnets, but that's not a solution you need to think about.

[@m.rieger8856]

We need an equivalent of the mind-o-meter for all kind of opinionated topics, so that it becomes fun for people to change their opinions from time to time. 😅

[@Xandros999]

I like it.

[@john-or9cf]

Hey! My old Alma mater (actually Case Institute, pre-merger) actually made it to Sabine’s radar! Whoohoo!

[@Zeuskabob1]

Thank you for the paper! There's clearly some very exciting progress ruling out options, and the galaxy rotation curve is running out of things it could be caused by. The more I hear, the more it sounds like there might be some "accepted fact" that we need to re-evaluate. I'm loath to say it, but I fear it may be the cosmological principle. I've heard that the principle holds holds less in larger observations than we'd expect, though anisotropy or inhomogeneity are even harder to grok. The MOND theory seems to have some serious weight, but it also fails to address the core issue at hand: we observe 1/r^2 for every close observation and 1/r for every distant observation. There doesn't seem to be a clear answer in MOND to resolve the dilemma. A rigorous theory would have to describe both behaviors using the same method, and MOND doesn't appear to attempt this (yet). Are there other areas in nature where we observe an effect that scales as 1/r^2 at short distance and 1/r at long distance?

[@hempbear]

MOND / dark matter is such a roller coaster ride!

[@Jeredin13]

The competing science is so good too. By researching both ends and everything in between, we’re bound to figure this out….eventually.

[@maya20484]

I know right? Just recently MOND's authors themselves published a paper ruling out MOND and now we have the opposite, really excited to see which model will win. Who knows, maybe a completely new model?

[@anthonylosego]

"Grasping at straws"

[@haroldcruz8550]

It's basically the aether of modern physics

[@JerkoFlapdoodle]

or QI, Quantized Inertia - a third candidate that has advantages over the other two

[@BigZebraCom]

I was going to modify gravity--but then things got really busy at work.

[@BigZebraCom]

@@HedonisticPuritan-mp6xv But I've just been assigned the Henderson Account! It's a nightmare!

[@Tletna]

You really should make the time. Modify gravity well enough and you'll feel as if a huge weight been lifted off your shoulders! (And, pushed onto the edges of galaxies...perhaps you could do the same with dishes, bills, and annoying house guests, too!)

[@BigZebraCom]

@@HedonisticPuritan-mp6xv That's a really good idea!

[@BigZebraCom]

@@Tletna Annoying house guests are the worst!

[@adamolig3865]

You have lots of paperwork at the Swiss Patent office, perhaps?

[@r.i.p.volodya]

I studied Theoretical Physics at university 25 years ago and I hated the idea of 'dark matter' even then. I was convinced that our understanding of gravity was incomplete. I'm over the moon to see this vid!

[@shawns0762]

The fundamental phenomenon of dilation explains galaxy rotation curves. Mass that is dilated is smeared through spacetime relative to an outside observer. It's the phenomenon behind the phrase "mass becomes infinite at the speed of light". A 2 axis graph illustrates its squared nature, dilation increases at an exponential rate the closer you get to the speed of light. A time dilation graph illustrates the same phenomenon, it's not just time that gets dilated. Neil deGrasse Tyson recently spoke about this. Dilation will occur wherever there is an astronomical quantity of mass because high mass means high momentum. This includes the centers of very high mass stars and the overwhelming majority of galaxy centers. It can be inferred mathematically that the mass at the center of our own galaxy is dilated. This means that there is no valid XYZ coordinate we can attribute to it, you can't point your finger at something that is smeared through spacetime. More precisely, everywhere you point is equally valid. In other words that mass is all around us. Dilation does not occur in galaxies with low mass centers because they do not have enough mass to achieve relativistic velocities. It has been confirmed in 6 very low mass galaxies including NGC 1052-DF2 and DF4 to have no dark matter, in other words they have normal rotation rates. All binary stars have normal rotation rates for the same reason.

[@jorelc6]

you mean over the MOND? 🙃

[@xNul]

​@@shawns0762are you saying that since dilation explains galaxy rotation curves, dark matter could still exist?

[@shawns0762]

@@xNul I am saying dark matter is dilated mass. When more very low mass galaxies are confirmed to have normal rotation rates it will be clear

[@TheLoneMitten]

I used to get cheeky on the old Twitter about being a dark matter denier. I'm not an atheist but agnostic but they didn't know that. It infuriated big cosmology.

[@charlesjmouse]

FWVLIW: I strongly suspect the answer is not "Dark Matter doesn't exist" in some form, or that "We have gravity wrong." It's that our current paradigm for modelling the Universe has reached the edge of it's utility and we are going to have to come up with a new paradigm if we can, if we are to make any further significant progress.

[@williamschlosser]

Amen. Try plasma cosmology, the only self-contained physical theory of the universe. All other theories, including BBT and MOND, are ad hoc curve-fitting with no physical explanation.

[@rapid13]

I always figured “dark matter” was just a place holder term for the unexplained phenomenon that has been observed.

[@johncmitchell4941]

Like some religious teachings, aliens, ghosts, and Bigfoot? 🙂

[@aretwodeetoo1181]

That's what they say when pressed, but it's a bad excuse and really not what they believe if you look at their behaviour. Call it "gravitational anomaly" then, or "dark gravity" if you really want to sound dumb. The expression "dark matter" is in my kid's books, the word "placeholder" is not. Not acceptable.

[@AA-ou9yd]

MOND bros… we’re so back…

[@Ian-nl9yd]

axioncels seething

[@AkaRyrye83]

No reason to fan-boy any position. We're just trying to figure out what the hells going on, and I don't care what the explanation is, so long as it's true 😅

[@arjavgarg5801]

​@@AkaRyrye83 nah it's a game and we pick teams

[@Vyshada]

Ah, yes. The famous MOND, and his brothers: MACHO (Massive Compact Halo Objects). WIMP (Weakly Interacting Massive Particles) And LACODAM (lambda Cold Dark Matter) In their infinite war with TEVES (Tensor Vector Scalar Gravity). Someone should make a comic of that.

[@danielgrizzlus3950]

@@AkaRyrye83 no, we pick teams and whoever is right gets more internet points

[@yureonice7917]

" bad news for dark matter " and then its just sabina smilling

[@Kokally]

MOND is the tanky end-game boss that absolutely refuses to die.

[@Kraflyn]

:D

[@ro4eva]

Yeah, like some pain-in-the-ass encounters from when I played WoW. Damn you, vanilla Naxx.

[@VikingTeddy]

Everytime it's beaten, it rises up but in a new form.

[@jorgmeltzer9234]

didn't anton petrov make a video where it was ruled out with some crazy 16 sigma confidence?

[@lwmarti]

I thought that MOND was some guy who won the Tour de France a couple of times. I've heard that the French think the world of him.

[@thirstyCactus]

So MOND is suggesting that f ∝ r⁻² at short distance, but morphs into f ∝ r⁻¹ when r is large? What type of function would describe the exponent as a function of distance?

[@timnelson4156]

What if gravity DOES fade as r^2, BUT the INERTIA is the issue? i.E. inertia decreases, so that even WEAK (r^2) gravity is sufficient? Has that ever been considered?

[@maval4537]

I'm a big fan since I first followed Sabine on the topic "What's currently wrong with physics?" a few years ago, she always impressed me with her courage to think innovatively, and since then I've been excited about everything she comes out with. An outstanding thinker and an extremely creative person, far beyond physics!

[@Thomas-gk42]

Same experience, couldn´t have said it better.

[@TAiCkIne-TOrESIve]

A critical thinker. An intellectually honest person. A true scientist.

[@olibertosoto5470]

Well, the ball is back in the MOND court. I'm taking a seat way back in the stands so I don't sprain my neck.

[@MGmirkin]

The ball should be squarely in Plasma Cosmology's court, as they've had the answer to galactic rotation curves since Anthony Peratt's ground-breaking 1986 papers "Evolution of the Plasma Universe I & 2," which seem to have basically been ignored [but damn well shouldn't have been]... Rotation curves fall directly out of plasma physics interpretations and modelling / simulation, no dark matter required.

[@olibertosoto5470]

@@MGmirkin Didn't know about this one at all. I'm curious as to why it's being ignored then but guessing on 2 possibilities.

[@AfonsoCL]

@@MGmirkin Get that pseudo-science out of sane discussions, please.

[@a.karley4672]

@@olibertosoto5470 The last time I compared the publication rate for MOND papers versus "Dark Matter" papers, there were about 70 DM papers for each MOND paper (51 vs 3429). Which suggests not that people are ignoring MOND, but that they're looking at it, and finding it un-useful.

[@olibertosoto5470]

@@AfonsoCL I vote we get the pseudoscience out of science.

[@mikloscsuvar6097]

00:49: Why not the centrifugal? Centripetal is directed inwards.

[@carlosmartinezbadia2532]

Obviously a mistake. The centripetal force in this case is gravity. Probably because physicists despise the term "centrifugal force", since it's just inertia. Thus, gravity finds a balance eith inertia

[@flemmingaaberg4457]

"Flat rotation curve" and the circle with a corner (the MOND meter) - love it!

[@DeSinc]

I never liked darkmatter. All barkmatter no bite

[@maxodidily]

This makes sense, Kirby has defeated Dark Matter to save Dreamland.

[@michaelkloebe1076]

The fact that we don't have a unified theory of quantum mechanics and gravity, and that we need to invent conceptual dark matter to account for flaws in our predictions of gravity, seems like more than a coincidence. I'd bet that a quantum gravity theory would dispel the need for dark matter.

[@Portents-Magic-imagination]

Well Freud invented the unconscious to account for the dark energy in humans…

[@fredred8298]

Sabine is singing, MONDay, MONDay, so good to me. 😊

[@billberg1264]

MOND Day, MOND Day, can't trust that day.

[@acasualviewer5861]

The MOND vs Dark Matter race is like watching the Olympic trial races, in really really reaaaally, slow motion.

[@DJCornelis]

From here it looks like a classic slapstick

[@ronm6585]

Thanks Sabine.

[@grodesby3422]

What could it mean for gravity to behave so differently at sufficiently long distances? Couldn't it be conceived of as being a different fundamental force to gravity?

[@peperoni_pepino]

A force behaving very differently at different scales is not new to physics. Most notably, the strong force is moddeled as electromagnetism-like (~1/r^2) at small scales but causes confinement (~r) at large scales. This is caused by the scale-dependence of the quantum theory. So what it really means is that the quantum gravity theorists can get excited about the renormalisation group flow of gravity. 😅

[@Currywurst4444]

All forces are forces and you can just add them together or split them.

[@yeroca]

What happened to those few observed galaxies that seemed to have been stripped of their dark matter, and so their rotation seemed to follow the 1 / sqrt(r) rule?

[@SabineHossenfelder]

If I've learned one thing during the years that I've worked on astrophysics it's that it's a bad idea to draw any conclusion from one particular or a few objects, it can prove anything and everything. Look at surveys, large samples, good statistics. Look for the rule, and try to explain the rule, before worrying about the outliers.

[@Jono98806]

@@SabineHossenfelder But surely, an actual law of nature cannot have outliers? Or, if it does, then the theory must either be abandoned or modified to explain the outlying data?

[@aureliontroll2341]

​@@Jono98806the point is that the law of nature of course doesnt have outliers BUT WE DONT KNOW THE LAW YET . If we can understand the majoraty of the cases we can better drawn a theory that explain all of them rather than try to explain all of them by the annoying different ones

[@bobboberson8297]

@@Jono98806 it's better to have a "law" that explains 99.9% of what we see in the universe than to have no law and no explanation for what we see

[@bautibunge737]

@@Jono98806 I think the point is that in astrophysics, error curves are so large no one even bothers to write them

[@wbwarren57]

Bigger Super Colliders!!! The answer is obvious no matter WHAT the physics problem is! Admit it, Sabine!!!

[@sharonreddy5557]

Better tools are always a goal. Of course, people who think money is the most important thing on Earth don't agree. Their billionaire buds aren't getting some.

[@soren6045]

Why not? The mankind is producing more useless, stupid records every day. Building a bigger collider with more energy or higher energy resolution should be a goal for itself. We spend billions for fast cars, sport and other „useless nonsense“. I work in semiconductor company to build chips that idiots use to make photos of there cats and post it in the internet. At the of the day we have ask ourself what is our goal as mankind? Complete stupidity or scientific progress.

[@zamolxezamolxe8131]

No, not no matter. But dark matter!

[@wbwarren57]

@@sharonreddy5557 actually I was trying for humor. Sabina rightfully criticizes those physicists who want larger super colliders to investigate almost any problem even though they don’t have a solid theory to test.

[@roryduff2252]

Sub quantum etheric density changes can explain these observations without the need for dark matter, dark energy or MOND. Its bouyancy type effect explains the bending of light too.

[@TheNewPhysics]

I solved this problem many years ago and haven't been allowed to publish my work. Would you help me, Dr. Hossenfelder?

[@heggedaal]

If this isn't a wonderful contradiction. MOND of weakly bound Binaries has been refuted by 16 sigma and now Dark Matter has no excuse for being around. There will be a very interesting explanation someday.

[@sebastiandierks7919]

By now it seems that neither dark matter nor MOND can be the full explanation with contradictory evidence against both theories. And both feels overkill due to Ockham's razor. Is there a third option?

[@mikicerise6250]

We're chickens.

[@evangonzalez2245]

There are a literal infinity of other options, we're just not smart enough to figure them out yet!

[@sebastiandierks7919]

@@evangonzalez2245 I don't think that's true. Either our theory of gravity, general relativity, is correct or it is not (on astronomical / cosmological length scales). These are logically exclusive possibilities, and there are only two of them. If GR is right, then we need more matter in the universe. Due to observations, it needs to be cold and dark. If GR is wrong, we need a theory interpolating between 1/r^2 and 1/r potentials assuming there is only visible matter. Of course the details, like what dark matter would be made of or how the interpolation between potentials looks like mathematically, may vary. But I don't think that's what you meant with "there are infinite options, we're just too dumb". Hence why I asked whether or not something is wrong with this logic and there is a third option, because I can't think of one.

[@williamschlosser]

Try plasma cosmology, the only self-contained physical theory of the universe. All other theories are ad hoc curve-fitting.

[@robertjohnsontaylor3187]

The more we learn the more we should realise how little we know and how much more there is to understand

[@glennmoss3285]

One over R squared works for a point source. A galaxy cannot be considered a point source at every givem.position. Calculating radiation exposure from different source geometries illustrates this... it's different for a point, line, or plane source. A galaxy is kind of like complex plane source, since it is disc like, but has very definite three dimensional qualities. It also does not have uniform mass distribution.

[@charlesjmouse]

Wild speculation: What if we are having trouble with this because we are making fundamental assumptions we have yet to prove that may in fact turn out to be wrong? eg: Mass and Inertia. We assume they are both aspects of the same thing without proof. But what if they are actually different things that vary similarly enough that they superficially look like aspects of the the same thing? How would that possibility effect our understanding, if true? ie: We take Gravity to be a force related to mass / inertia *or* a consequence of how mass / inertia distorts space-time. Each a different perspective on the same thing because 'we' haven't completed our understanding sufficiently. But what if 'mass' and 'inertia' are different things entirely? For instance, 'inertia' distorts space-time only and 'mass' only acts as a force? How might each vary separately to result in observation? Nonsense? The Strong, Weak, and Electromagnetic 'forces' are all considered to be separate 'entities', all with their own 'rules' and behaviour. But to an extent they all vary together because they are all in some way related to the matter upon which the act... or the other way round.

[@themostselfishman]

That MOND GoT joke was incredible.

[@philipcoltharp918]

She pulled that joke out of no where, like a theoretical physicist explaining galactic rotational curves.

[@yeroca]

I prefer mon-DOM-eter as a pronunciation, kinda like speedometer. The mondometer is sitting at about 75! Maybe we can take bets on the next direction and magnitude. I"ll wager that the next is a +5.

[@NoNameAtAll2]

75 factorial

[@ada7180]

Another possibility is electromagnetism. Magnetic fields, Birkeland currents, plasma, etc. But this is a scary thought.

[@esecallum]

This topic is banned by the gatekeepers of astronomy I mean astrology.

[@ada7180]

@@esecallum don't insult astrology, those people have more integrity than astronomers/theoretical physicists

[@esecallum]

@@ada7180 well said. Astronomy has been turned into a pseudoscience.

[@Sabimaru1]

Love your videos and the MOND-o-meter!

[@therealjammit]

For me my interpretation for dark matter/energy was as a placeholder name for an effect we didn't understand, not an actual "thing".

[@KaaneDragonShinobi]

There are theorists out there who tie the concept to hypothetical weakly-interacting massive particles (WIMPS), so they in particular view dark matter as actual matter we just can't detect.

[@CallOfCutie69]

0:38 Nice

[@CallOfCutie69]

1:56 Angela Collier would hate you, because, according to her, Dark Matter is not a hypothesis, but a problem, and MOND is one of the solutions to the Dark Matter problem. She would lose her shit when seeing 1. Dark Matter 2. MOND list…

[@jasonosunkoya]

Shes about to complain that she's going to get another spike on her video.

[@SolidSiren]

Dark matter is a problem. But MOND doesn't fix it.

[@blackshard641]

This is because Angela Collier is an egotistical child. She's clearly very well educated when it comes to physics, but she has more than a little to learn about science communication.

[@Rampart.X]

How does a "problem" obviate a hypothesis, which DM clearly is?

[@hearteyedgirl]

just watched that exact video. dark matter problem itself is poorly named, it suggests there are masses unobserved that cause anomalies can't be explained

[@1965GJS13]

Q: "Is dark matter real, or is the problem that we don't understand how gravity works?" I am firmly in the second camp. But that's just me. Dark matter just seems too much of a "cludge". The universe in elegant, and dark matter is not elegant. Same argument for so-called "dark energy".

[@riggsmarkham922]

Have you seen the standard model? The universe is decidedly not elegant. Sorry that the universe and the data don’t fit your aesthetic preferences

[@williamschlosser]

A better name of dark energy would be pixie dust, like in Peter Pan. If you are tired of complicated theories that are nothing more than ad hoc curve-fitting, try plasma cosmology. No dark fudge factors needed.

[@andrijapfc]

Sabine wrote a whole book about how this obsession with elegance is wrong, this how I first heard of her...

[@coololi07]

interesting development! Was surprised you didn't discuss the limitations of this paper today.

[@gregoryclifford6938]

So if particle condensate is dispersed in and far beyond the visible disc, until gravity draws it into the way of bosons or other particles that form a nucleus, then a strong 'like' force must spin and repel them. Sort of like magnetic repulsion? Opposite mates bring gravity in and 'like' matches pushes them apart. Is that why entanglement exists in the same nucleus? Is that what is dispersing them in interstellar space too? If gravity would otherwise crush atoms into condensate, without the repulsion or at least substantial turf protection, what is the 'like' (more appropriately 'dislike') force that does it? And who let it in the door anyway? Gravity brought the condensates to a central mass, bosons made more matter, and they rode together into a sphere that absorbed the gravity carrier. By the conservation of energy scheme, how was gravity not converted to a split spin propulsion pattern that collides internal quarks or whatever with ever-growing energy? Isn’t that why 'like' atoms have varying energy levels in chemistry? Higgs and Pions, is that all who are causing drag and rowdiness in the celestial block party? Or does Sabina have more for the next episode?

[@charlievane]

maybe there are just THAT many dyson spheres

[@fredrik241]

Dyson spheres suck!

[@charlievane]

@@fredrik241 meaning they exhibit negative pressure?

[@fredrik241]

@@charlievane Yes and they're expensive!

[@majorhumbert676]

Dyson spheres wouldn't even be that massive. Besides, what's the point of a Dyson sphere that doesn't interact with light

[@sudazima]

just to remind people, even MOND models have extra dark matter particles in it to make sure the CMB comes out right. so really it has a similar problem itself anyway as well.

[@AR15ORIGINAL]

CMB?

[@asleeds]

@@AR15ORIGINAL Cosmic Microwave Background. The background radiation left over from the VERY early days of the universe.

[@rogerjohnson2562]

A proper understanding of MOND will probably also explain CMB. CMB is currently thought to be the remnent of a Big Bang followed by an inflationary stage followed by a varying expansion rate; aliens are laughing at us! 🙃

[@riggsmarkham922]

⁠@@rogerjohnson2562MOND theorists don’t even try to fit their theories to the CMB or bullet cluster evidence, their calculations can barely fit the rotation curve data.

[@Thomas-gk42]

Lovely! I still love your work on superfluid DM you did together with some of the authors of the new paper, but I assume that doesn´t fit the new data either, or does it? I also love the gym-boy on the beanbag, but unfortunately love is not sufficient to explain the universe. Thank you so much for keeping us updated.

[@SabineHossenfelder]

a little bird told me they're looking at what this means for superfluid dark matter...

[@Thomas-gk42]

@@SabineHossenfelder 😅👌

[@GreatPhysics]

@@SabineHossenfelder Superfluid vortices?

[@Thomas-gk42]

@@GreatPhysics The switch from fluid to superfluid, guided by the temperature, would explain the discrepancies between DM and MOND. The superfluid phase creates a quantum field that works like gravity and explains the flat rotation curves, as far as I understood.

[@larryburford1871]

Newton says: a proportional to 1/R^2 _No adjustment/exception for R equal 0 _No adjustment/exception for R equal infinity We can't be sure, but both extremes seem VERY non-physical to me Einstein goes to Newton in the small field approximations, so He has the same non-physical difficulties Fix one, fix both (probably) So far as experiment and observation tell us, we are VERY CLOSE, but we are NOT THERE Our equations, good as they are, are known to be not quite right ... We have nothing better (Our spacecraft DO go where we expect them to go) (It is just the far away things, or the really small things, stuff we can't see, stuff we can't touch, that give us gas) MOND of SOME SORT has to be involved in moving forward, IMO I suspect we are missing the point of, misinterpreting the data for, Dark Matter, and Dark Energy All of our conclusions are, of necessity, theory dependent Perhaps our First Principles need some re-thinking? Food for thought, rather than actual answers We ARE doing something wrong BTW My avoidance of QM in the above is intentional We need to make sure our foundation is solid before we worry about the leaky roof

[@maladyofdeath]

How does any of this make sense? Space is expanding yet the force of gravity is constant? Shouldnt an expanding space weaken gravity over distance?

[@GrahamChristie-jg8sw]

The ultimate solution, if one exists, might involve a combination of MOND and some form of Dark Matter. It's possible that multiple problems are being addressed with a single solution. You may need a gauge with a split needle indicator

[@Jono98806]

What happens of the real is neither of those but something different altogether?

[@fredrik241]

@@Jono98806 Well if we believe the Many Worlds theory there's going to be a universe where any combination holds true. So its all good and correct!

[@enderwiggen3638]

@@Jono98806it’s theoretical physics … none of it really matters. They just get paid to research what they want and the results try to predict what we observe … whether or not it is reality doesn’t matter

[@bautibunge737]

@@fredrik241 That's not how the many worlds interpretation of QM works

[@thesenamesaretaken]

Well yeah, because neutrinos exist.

[@DarkskiesSiren]

I like the mond-o-meter

[@theslay66]

Here's my bonker take on the subject : Dark energy and gravity are the same thing. Empty space exerts a negative pressure on anything around it. However, the presence of matter lowers the exerted pressure. The more density and proximity of matter, the lower is the exerted pressure. What we interpret as a gravitational field is a gradient of this pressure. An observer will fall onto a planet because the patches of space below him exerts less pression than the patch above him, resulting in a force directed toward the planet. On smaller scales (from the size of a stellar system to the size of a galaxy) where the average density of matter is rougly even, distance is the main factor for the strength of the effect, and mostly change according to the squarred distance. When considering larger scales, where density can vary a lot, it becomes more prevalent as pressure from the less dense regions of the galaxy increases the effect on more dense regions, which leads to an overall prediction similar to MOND's. Between cluster of galaxies, the pressure reaches a maximum value that we interpret as dark energy. Here we go, we got rid of both dark matter and dark energy in one loop. But that's not all because : When matter density reaches a treshold, empty space pressure becomes null and can't go beyond that. It basically means that gravity has a maximum value. Which means that we get rid of the singularity at the center of black holes. Matter cannot infinitively fall onto itself, if the force applied on it can reach a maximum. So, am I a genius or not ? Please do not take this seriously, I'm just having fun with some ideas -but I'm pretty sure an expert on the subject would quickly find some huge gaping holes in that rambling of mine.

[@peperoni_pepino]

Reminds me of the old 'infinite bombardment' theories for forces. From all around us, infinitely far away, someone is shooting, many tiny balls of force at us. When you are above the Earth, the balls coming from above will hit you, but the balls from below are blocked by the Earth. Therefore, you are hit by more balls from above than below, so you are pushed towards the Earth. (The Earth is slightly pushed towards you, but your 'shadow' on the Earth is much smaller than the Earths 'shadow' on you.) If you call the number of those tiny force balls in a certain volume 'pressure' (because the pressure of a gas also consists of a lot of tiny balls bouncing against the walls), you get something similar to your idea. The obvious problem with this idea is that gravity depends on mass rather than volume. That problem might affect your idea as well, depending on how the mass rejects the pressure.

[@kennethferland5579]

Don't need to explain Dark energy, it was nothing more then an error caused by ignoring that the local universe in a low density bubble which pulls away from us. It was all just an embarasment jump to conclusion by the scientific community that no one wants to admit to untill the folks that both awarded and recived the Nobel prize are all dead.

[@theslay66]

@@peperoni_pepino That why I suppose that the pressure is inversely proportionnate to the density of matter. But it also takes place inside the earth -after all, there is plenty of empty space between atoms. However, as matter gets more dense, there is less space between atoms, so there is less pressure from it. Until we get to a state where matter is so dense that there is no more space anymore between atoms (or whatever exotic particles matter devolved into at such a density), and so the internal pressure from space reaches a minimum. But in a sense it's not really different from this bombardement idea, if those tiny balls were shot from empty space itself, in all directions. And the more matter there is, the less of these balls can pass through. To me the obvious problem with this idea is where does the energy of these balls come from, and what happens to the kinetic energy when they are blocked by matter. It would be a constant source of heat coming from all around space, and quite a strong one if it would be able to accelerate an object as strongly as gravity can. And we know that in empty space, objects tend to radiate heat and cool down, they don't spontaneously heat without any apparent source of external energy. That's why I prefer to see it as some kind of "flow" of space in all directions, like if each part of space was a souce of water, and matter acts like some hole where the water can flow into -the more dense it is and the steeper the slope gets. Of course behind this there's the idea that the equations of General relativity could be reused and adapted to this new interpretation. The goal here is not to reject the previous theories, but propose a new perspective that would still be consistant with what we have today.

[@jankara1754]

Well, it seems you've described the idea that's called "Entropic gravity" (en.wikipedia.org/wiki/Entropic_gravity). Eric Verlinde is one of the main proponents of it and frankly it makes a lot of sense to me...

[@rickyfitness252]

Wrong and gay.😮

[@a6hiji7]

What about your paper that showed that MOND shows up as correct only with low quality data? Is MOND now compatible with good data as well and is no more a statistical error?

[@paradossoDFermi]

0:48 the centripetal force does not balance the gravitational pull; gravity actually is the centripetal force that allows rotation. No gravity, no orbit.

[@hamishfox]

I already didn't understand dark matter but now I'm about ready to start crying.

[@DaveWasThereMan]

It's all fake nonsense. Show me what this creep lady has produced, that doesn't help ruin society with this useless influencer economy.

[@tuomasronnberg5244]

It's okay you don't need to understand dark matter anymore, it's MOND time now.

[@williamschlosser]

Nobody does, and the honest ones will admit it. That's because it doesn't exist.

[@GH-li3wj]

The acceleration needed to keep the galaxy in shape is the same for all galaxies in the Universe, which explains why the MONDoMeter will head towards MOND in the end. But the MOND theory doesn't explain anything, this theory modifies Newton's theory that everyone naturally understands with something that seems totally bizarre that nobody naturraly understands.

[@thalasyus]

The thing is, MOND cannot be right because of the Newtonian part. We need a better modified gravity theory based on relativity.

[@heronstreker]

Is mond just one formule is it a class of them? I imagine one can modify Newtonian Dynamics in an infinite number of ways.

[@Tletna]

Relativity systems/equations are compatible with Newtonian physics (just more complex). Though I suspect both are not 100% correct but just the best we got currently for relativistic and non-relativistic scenarios. Neither does a good job addressing quantum physics though. There is no perfect model for the physics of our reality and we're ever improving what we got (or trying to at least).

[@bautibunge737]

It cannot be right because it's not quantum too, but the point is whether it gives better predictions than newtonian mechanics + dark matter with fewer free parameters

[@horeca-tech6741]

the space is just rotating around the center of the galaxy with invariant tangent speed, if you see stars are in a "strange" rotation with constant speed, then this must be the space itself is involved, this is a straight forward assumption

[@MasterHigure]

0:50 The gravitational force IS the centripetal force. The centripetal force is the force that points inward and keeps an object moving in a circular motion. It's the _centrifugal force_ which, from the object's own perspective, is the equal and opposite force to the centripetal force, and it is this centrifugal force that is trying to tear any rotating object apart.

[@DinsDale-tx4br]

1:45 If you remember, in an earlier video you suggested that gravity inside a sphere was perhaps Null. This time, inside a dark matter hull it is not Null. Rather confusing what?

[@Highcaloriegrappling]

It seems to me - being an uneducated fool - that the search for gravtrons and the dark matter/mond question is really that we don't understand how gravity works at either scales. To me, gravity seems to be an emergent property of our universe and not an actual force per se?

[@hotbit7327]

Gravity is not a force in Einstein's theory for 100+ years, already.

[@Thomas-gk42]

You are surely not a fool, friend, being here and watching Sabine. And your thoughts are smart too.

[@Highcaloriegrappling]

@@Thomas-gk42 thank you kindly

[@majorhumbert676]

We don't really understand how gravity actually comes about. I.e. how is it that gravity appears when there's mass? But at least it makes sense that it dissipates with r^-2 because we live in a three dimensional space. MOND would make sense in two dimensions, but maybe it's some holographic hocus-pocus taking place. WIMP seems to be an easier explanation though.

[@CharlesOffdensen]

5:00 the drama!

[@blackest3314]

I feel some scientists have too much reverence for old theories and try to "make stuff up" in order to accommodate them. Dark matter seems one of these cases. If a theory doesn't explain well the experimental results we should modify the theory, not postulating invisible stuff up. MOND feels like a way better approach to the problem. Even if it doesn't turn out the "right" one, we should still pursue that direction. It's the same way I feel about the multiverse interpretation for QM. Basically some scientist prefer to choose some untestable pseudoscientific concept instead of accepting the idea that the theory is simply "wrong" and needs to be fixed. I honestly think it's pretty sad and unscientific.

[@michaelpieters1844]

Agreed.

[@sillyking1991]

Thats the thing that isn't really widely understood by the general public. Dark matter came about as a result of finding real world examples of things that don't match what our current theories predicts. So scientists are trying to figure out what about our current understanding of the universe is incorrect. one hypothesis is the existence of some previously unknown matter. another possibility is that our current model for gravity is wrong in some way. different groups of scientists are working to find that hole. So they're doing what they have always done. they're poking around with a stick until they find the hole. its not about reverence for past theories. its that the whole point of science is to follow the data. and up till recently all data pointed to a particular model for how gravity worked. and now that they've found some contradictions to that model, they're looking to figure out where those contradictions came from. this is exactly the behavior we want.

[@michaelpieters1844]

@@sillyking1991 Special relativity (and by extension general relativity) is full of contradictions and many people have highlighted them now and in the past, yet the scientific establishment puts blinders on their eyes and refuses to see it.

[@sillyking1991]

@@michaelpieters1844 care to give examples?

[@michaelpieters1844]

@@sillyking1991 Maxwell-Hertz electrodynamic theory is Galilean invariant. The queen of electrodynamics is Ampére's Force Law which was deduced from experiments and can be obtained through Weber Electrodynamics which is also Galilean invariant. It is superior to Lorentz Force which was just theoretically assembled together by Lorentz using one force component from the stationary frame and another part from the moving frame. Lorentz force does not conserve linear momentum. Ampére's force conserves linear momentum. The Michelson-Morley experiment did not give a null-result but obtained a velocity of the Earth that was much less than what was assumed in a time when mainstream science claimed the sun was fixed relative to the nearby stars. There are no positive detections of special relativity in the photon sector, only null results 'confirming' the theory. There is no experimental evidence for the invariance of the speed of light with regards to the observer/detector. If there is a relative velocity present between the Earth and a nearby Star, relativity claims the light of that star has a relative velocity c with respect to both the Star, the Earth and any other moving body. There is no experimental evidence for Lorentz-Fitzgerald length contraction. There is no experimental evidence for relativistic stellar aberration. There is no experimental evidence for relativistic source brightening. Classical Sagnac effects contradicts Special Relativity but mainstream science claims relativity does not apply because of the rotating equipment to be a non-inertial system. A first order timing correction due to Sagnac effect is required to make GPS work. The fact that it requires such a correction is in direct conflict with Special Relativity. In their famous 1972 paper Hafele & Keating did not publish the original test data. An analysis of the original data by Kelly tells relativistic time dilation is not proven. Einstein and Arthur Eddington predict a 1,70 to 1,75 arcseconds radial displacement of light due to gravitational lightbending. The correct calculated value according to Einstein's theory is in fact 1,1 arcseconds, as calculated by Charles Lane Poor. General Relativity can not predict both the radial as the direction of gravitational lightbending, given the experimental data. General Relativity can not predict the discordance in the perihelium of Venus. General Relativity can not predict the discordance in the perihelium of Mars. General Relativity can not predict the discordance in the node of Mercury. General Relativity can not predict the discordance in the node of Venus. General Relativity can not predict the discordance in the eccentricity of Mercury.

[@Demobius]

My unsupported opinion is that the next breakthrough in cosmology will come from topologists. I don't think we are seeing what we are looking at. Reconciling MOND with general relativity will require extra dimensions.

[@TerryBollinger]

5:04 “Theoretical physics is keeping us all on our toes.” A modest correction: _“Observational_ physics is keeping us all on our toes.” Science is - and always should be - driven first by scrupulously derived experimental and observational data. This is a delightful example of just that phenomenon.

[@michaelpieters1844]

Agreed. The best physicists are the ones who do their own experiments and build solid consistent scientific models. These days too many high functioning nerds sucking the wildest ideas out of their thumb.

[@TerryBollinger]

@@michaelpieters1844, um, ouch. For example, this nicely solid finding that orbital velocities are too high at extreme galactic distances required the use of advanced astronomical equipment created by decades of work by thousands of scientists and engineers, and also deep knowledge and clever use of general relativity. One person experimenting in a lab can still uncover amazing stuff, but usually with the help of advanced equipment, mathematics, and software since other folks picked most of the low-hanging, minimal instrumentation fruit centuries ago. Even back then, some of the lab experiments were so precise and meticulous that no one has repeated them since. Proof of Maxwell’s light pressure prediction is an example. What’s dangerous is explicitly choosing to disconnect your musings from any obvious possibility of experimental verification, which is what “super” string theorists (now just string theorists) did in the late 1970s. That’s not permitted in any scientific methodology, let alone physics. Not surprisingly, once its founders abandoned the annoying (to them) constraints of experimental verification, their movement quickly turned into a rather odd but well-funded gnostic numerology cult that neither cares about nor acknowledges multiple experimental disproofs of their musings. They even have prophets - folks that other cult members adoringly describe as “a million times smarter” than mortals like you or me. (That happened.) On the positive side, the resulting non-predictive papers make outstanding garden mulch when properly ground, watered, and seasoned with manure.

[@Limrasson]

If I understand it correctly then "Dark Matter" and "Dark Energy" is essentially just science speech for "Fuck if we know."

[@henrycavanagh1259]

You dont understand it correctly.

[@Vgamer311]

@@henrycavanagh1259theyre pretty close. Dark matter isnt a theory, per se, its a blanket term for the problem of our models not matching our measurements. And there are a bunch of theories about why that is, but none of those theories are called “dark matter”

[@TheMarrethiel]

Sabine, I think you'd be better off visualising it as a triangle. MOND and DM on two points and "Something Else" on the third.

[@fallwitch]

One thing that irks me about this debate is no one ever suggests that perhaps our method of measuring how much mass is in a galaxy is fundamentally incorrect. If we are using bad data we will get bad returns.

[@donaldduck830]

Indeed. We are looking at the one spot under the streetlamp for our lost keys, which we lost somewhere in the dark. This is madness and lazyness on the part of researchers, but somehow, like AGW-crowd, they managed to acquire funding via corrupt politicians.

[@CyCloNeReactorCore]

I definitely agree. A similar study should be done for a galaxy that displays strong gravitational lensing so we have a more accurate picture of the mass. This might have been thought of already though

[@brenta2634]

The different methods agree, though. Gravitational lensing and luminosity produce the same mass, so BOTH would have to be wrong

[@justsomeguy6474]

Sure, all you have to do is prove the data is bad.

[@brenta2634]

@@justsomeguy6474 How?

[@n-da-bunka2650]

I have always been a MOND or something other than "dark matter" pundit for some time now. Good to see others reinforcing such hypothesis.

[@PeteSmoot]

OTOH, I seem to recall they looked for gravitational lensing around colliding galaxies. They could show a huge chunk of mass kept moving after the collision while the visible matter did not. That was good evidence for dark matter. Not being a cosmologist, I have no idea whether that should be convincing.

[@robmorgan1214]

Quantized inertia ALSO predicted flat curves with ZERO fit parameters. It's a better theory... despite the obvious conceptual issues it creates, relying on the explicit rindler horizon etc... however, it's possible it may be right for the wrong reasons, and the rindler horizon may be an unnecessary assumption or simply an incorrect interpretation of the calculation.

[@Knapweed]

Time at the centre of a Galaxy passes slower than time at the edge because there is far greater mass at the centre compared to the edge. This would result in the edge moving faster than expected.

[@rocketsroar1]

MOND actually doesn't "predict" anything, it is just adjusted to fit whatever pops up.

[@kennethferland5579]

You can say exactly the same thing for DarkMatter.

[@AG-ld6rv]

It's an equation. You can calibrate it on a handful of galaxies and then see if its predictions match other galaxies. Once everything matches everywhere, its predictions seem pretty solid. From what I understand, MOND & dark matter/energy both do not fit observational data in 100% of cases. This MOND & dark matter/energy stuff is an active area of research for a reason.

[@majorhumbert676]

What explains MOND? In WIMP, I can kind of see what what is going on, but with MOND it just seems like we're over-fitting some formula.

[@AG-ld6rv]

@@majorhumbert676 Well, science isn't always about explaining stuff in a way that matches intuition based on human experience at the macro scale on Earth. You should watch that nice interview with Richard Feynman trying to "explain" magnetic forces. He basically spends 7+ minutes discussing the philosophy of explaining a cause and concludes we simply know the force exists experimentally. When you get to the foundations of physics, things can become a little weird.

[@laposgatti3394]

@@kennethferland5579 no

[@PapaNoahful]

MOND is the anime side character that any German speaker immediately realised will have a story arch about the moon later

[@simongross3122]

Yes. Mond means moon, earth or mouth, depending on where you are.

[@MathIndy]

Sabine, please do a video on quantized inertia theory! Mike McCulloch's quantized inertia deserves the serious attention of the physics community.

[@zondaroy9525]

Okay, so this is another paper from the subset of people who described the rotation curves (you covered this in one of your earlier videos) using MOND. So these are two solid evidences against DM. Is this a fair characterization?

[@RandyScottGuitar]

MOND is the astrophysical phoenix that always seems to rise from the ashes.

[@thingsiplay]

MOND, the chosen one VS Dark Matter “It's not about how hard you hit. It's about how hard you can get hit and keep moving forward. How much you can take and keep moving forward.” ― Rocky balboa Sylvester Stallone

[@chrisdewitt532]

Another example of why we need to spend more time challenging “settled science” and less time trying to push leading theories into the “settled” category in order to punish people with opposing thoughts. Let the crazies be proved crazy over time instead of scientists abandoning their principles to score short term political or popularity points…

[@gavinriley5232]

Well I am actively writing a paper, and we were actively battling with how to explain the fact that our DM model produced rotation curves that were flat far further than previously expected. This new paper is actually highly important for us. No need to try and explain it away, our bug now becomes a feature.

[@billberg1264]

Okay, so the study utilized gravitational lensing. And it points towards gravity working differently than our traditional models. But if we need to update out gravity model, wouldn't that change the amount of gravitational lensing we expect?