MORE evidence AGAINST dark matter? | What does the GAIA data actually show?

[@DrBecky]

A HUGE thank you to my colleague Harry Desmond (Senior Research Fellow, ICG), who has become my go-to for chats about this field of modified gravity and who helped me understand the context of this new research paper in the field.

[@Scotian6444]

Idk.. but the surface speeds of stars and size is interesting.. sfm... surface feet per minute compared turns out near the same... what if black holes are not so black.. that they can transition between.. popping back into the visual spectrum emitting large amounts of energy.. could you get large contractions in the accretion disk.. or expansion... matter at boundary migration and density of particles...

[@RWin-fp5jn]

A very well-balanced discussion about the decennia old dilemma of dark matter vs. MOND. Well prepared for sure. The obvious truth however is that neither is correct. We have been somewhat careless in our problem description. We simply state: ‘..we are seeing unaccounted gravity in galactic spiral arms…’. Not so fast. Since gravity is nothing but contracted spacetime, we can also re-brand the problem description as ‘…we are seeing missing spacetime in the galactic plane..’ This sounds equally weird as supposing an extra ingredient (dark mass). But it actually the preferred option because we are not suggesting anything new, but in contrast we are suggesting the lack of something we know to exist (spacetime itself). Moreover, the suggested lack of spacetime is a KNOWN phenomenon in physics as there is no spacetime between the area between an atom’s nucleus and outer electron orbits. Here electrons move in terms of energy and mass, never in terms of space and time. So then, if spacetime in our galaxy is emergent around stars as overlapping bubbles, then the area between the spiral arms will have almost NO spacetime (since almost no stars). Thus, we must subtract these gaps form the APPARENT distance between outer galactic arms and galactic core. Thus, the distance is far less then appears and so are the absolute rotational speeds form outer stars. This solves the ENTIRE issue of seemingly too fast seeming rotation speeds. Would love for Becky to spearhead this third ( and correct) option.

[@anthonywilliams7052]

Dark Matter only exists in the Futurama Nibbler's litterbox.

[@blueredbrick]

hello RWin-fp5jn; Love your insights and extra wisdom on this topic but "(and correct)" is your ego bubbling through. Nothing wrong with that at all but be aware of it in the neutral sence. Even the king is naked without clothes. And no, English is not my native tongue and I will not bother installing a spell or grammar checker. Still I learned A lot from your writings so thank you. @@RWin-fp5jn

[@breakdancinfool]

I dont buy it. To overtake Relativity, MOND would need to bear HIGHER ACCURACY IN ALL TEST CASES. Every single case we've put General Relativity to come up roses...it fits nearly perfectly into every measurement and observation as well as being supported by mountains of data. MOND doesn't fit into everything well without some data interpretation gymnastics. It has very little data to support it and has not been through the rigors of testing in all applicable cases. It is a LONG way off from being taken seriously as an alternative to relativity - or it should be. Feels like ambition and hunger for research grants may be causing too many physicists to jump the gun on this.

[@junkerzn7312]

It absolutely cannot be 10 sigma with so few data points shown on that graph. Not only because the scatter indicates massive issues with data integrity (too many unknowns), but also because there are simply not enough data points on the plot to make up for the massive scatter in the data. Obviously what has to happen to resolve this issue is to come up with a way to measure the unknowns so the data can be tightened up. Until that happens, no amount of statistical analysis is going to right this ship. These papers are showcasing a classic, classic mistake made by researchers trying way too hard to squeeze something definitive out of spaghetti.

[@vastrop345]

FWIW, there's much more data than the graph: 26615 wide binaries in the "main sample". But the diverging papers make a lot of diverging assumptions in the characterization of their samples, select their samples on different criterias, apply different modelings... It is really a mess. The line of thought on how he gets approximatly 10 sigma starts at page 19 and one can form one's own opinion. My gut feeling is that those papers won't blow up on gross math mis-application but rather on the many shaky assumptions they are based on, some of which being treated as certainty even if they don't deserve to be. Anyway, everyone has conclusive results, even if they differ, which is a good basis for further research (and employment ;) ) Sure way to keep everyone happy.

[@MultiSteveB]

13:42. "The name is MOND. James MOND."

[@georgegyulatyan3263]

Question. Where do you think Erik Verlinde’s concept of Emergent Gravity stands? Personally, I am also in the camp that “dark matter” is not matter. Had we not chosen that name, and just accepted that it is an observational disagreement with current theories, we’d have gone much further towards formulating a better theory of gravity rather than wasting time looking for some nonexistent “matter”.

[@travcollier]

Sounds to me like they did a bootstrap analysis to get the confidence. Simulate a a bazillion binary systems (fairly easy) to get the expected distributions, then calculate the probability that the actual data comes from those distributions. It is a legit approach, and pretty simple though computationally expensive. If your intuition is based on linear regression or something like that, I can see it looking impossible.... but that's not what's going on here.

[@geoffstrickler]

All they have shown is that their simulation matches Newtonian gravity/relativity better than the data from GAIA. That doesn’t mean their analysis of the GAIA data is 10 sigma, nor anywhere close. It’s a gross misuse of statistics.

[@Scott-.]

I saw this paper pop up in science news and thought to myself "I'll wait for Dr. Becky to do a video on this, I bet the headlines is sensational and there's probably some issue with the paper" My trust in you was rewarded, thanks dor the breakdown Dr. Becky!

[@jirofeingold3640]

I was watching this (having read an article in a science magazine that didn’t give as good context) and thinking to myself I next time I’ll wait for this explanation

[@steveDC51]

Likewise.

[@steveDC51]

@@Bryan-Hensley I still believe that the BBT is still the best model we have to explain what we are capable of observing. Not saying that was the beginning of all we see just that it’s as far back as we can see at the moment. There had to be something before surely?

[@JennySimon206]

​@@Bryan-Hensleyyep, hilarious 😅

[@markanderson3740]

@@Bryan-Hensley the simplest way to describe the creation of our baryonic universe, with all it's fancy forces held in balance, would be a state change of an unknown pre-material suddenly given purpose by an unknown energy influence. there had to be enough energy to create sub-atomic particles and singlet hydrogen. after that the whole system is set in motion. hydrogen captures more energy to doublet. then to make He and doublet again, then Li. in truth singlet hydrogen is also likely the final remnant of a dead BBT universe, but conditioned to fizzle and spark activity, lighting the cold empty space by chance. until extinction by exhaustion. perhaps the 'voltage of creation' is a quantum value, a metered dose that creates the whirl of universe building just until the energy runs out and it all unravels again. Every atom is a miniature 'eddy'' created to exist until the captured energy is worn away by the friction of existing. to try to misrepresent the smallest particle as not existing is to insult every 'order of scale' we have witnessed in our universe. thinking our BB was the only BB that ever, and will ever exist, in the potential of a super-universal framework of time is practically religious, and I use that barb only slightly lightly :) absurd.

[@jasnarmstrng]

Science commentary done right for the masses; much appreciated, Dr. B!

[@justinwalker4475]

or just use your brain.. seriously

[@FLPhotoCatcher]

Here's my hypothesis that could explain gravity, dark matter, and maybe even dark energy. I came up with it about 5 years ago. The multiverse (if it exists) explains gravity. Have you heard the vacuum decay of the universe? Well, it may be happening all the time, hundreds of times per second, but we survive because of the multiverse - in at least one, we live on to observe everything. But the dissolving universes that vacuum decay disperses in other universes, turn the planets and every object into a gradient of electro-magnetic waves and maybe subatomic particles. These electro-magnetic waves in other universes (from now on called the background EM gradient) attract atoms in the universe we observe. This *gradient* of photons and particles in other universes refracts light and matter (matter being made of, basically, energy waves) toward the center of mass of any object. Over some length of time, the influence of the other dissolving universes fades away, such that the background EM *gradient* is stronger than expected on the outskirts of galaxies. This could explain the rotational curves of galaxies, and therefore dark matter. My hypothesis might even explain "dark energy." It's hard to explain, but basically, there would be very little universal gravitational pull slowing the expansion of the universe, since in the beginning, everything was moving outward at the speed of light, with little time for significant background EM gradient to have formed. When galaxies and galaxy clusters formed, they would be moving faster or slower based on *when* they formed. Thus, the expansion of large parts of the universe would look faster or slower than expected. This may explain why astrophysicists have two differing figures for the age of the universe - it is based on their flawed calculations of the past expansion of the universe, and how it worked. And my hypothesis might be able to be tested. A large mass could be put on a train car, with sensitive gravity detectors nearby that can determine if the large mass is there or not. Using a random number generator based on radioactive decay, the large mass would be - as quickly as possible - moved away if an unlikely radioactive particle hits a detector. In those other universes, the mass would *not* be immediately moved, so the gravity would not change as fast as expected.

[@TheDanEdwards]

Not sure I agree. Dr. Smethurst does a good job in explaining astronomical observations, for sure. However, she is not so aware of the culture wars in which she (and we) are embedded. Or perhaps she is aware but because of the society (UK) in which she lives she is restrained.

[@figefago]

@@FLPhotoCatcher Multiverse is science fiction :) Nature does everything as simple as possible and if something is possible to create having one component then other components is not need :) Thats why three dimension of space is enough to create universe. Space is not curved, newtonian absolute time exists etc :D Mathematical description can be very complicated and tricky but nature doesn't care about it :D

[@richardkammerer2814]

If I use my brain, it’s not going to be serious.

[@Andrey-il8rh]

I just discovered your channel through this video and instantly subscribed. Your way of presenting the information is very engaging. I wish physics and mathematic fields had more people like you who could not only understand the complexity but also docompose it into highly digestible form for those not so deep in the field. Well done ❤

[@Jh00tube]

Dr. Becky, I just wanted you to know that a lawyer in Brazil who shouldn't be paying any attention to anything other than paperwork is actually watching you religiously with awe every time you upload a new video. Thank you so much, I love your work and I would be super excited if you sent a shout-out! ;-)

[@john-or9cf]

Looking at your scatter graphs reminded me of the analysis we did with Pageous satellite date waaaaay back in the mid-60’s. The principal investigator on the project took the raw data, threw out the data points he “considered” wrong, drew a straight line through the rest and voila, we had a nice linear answer! We recorded the noisy photomultiplier data on a strip chart along with timing pulses from WWV and since I was the only one on the team who knew Morse code, I got to interpret the PMT timing data. Ah, the good olde days!

[@vigilantcosmicpenguin8721]

I never considered that there was once a need for Morse code in statistical analysis.

[@john-or9cf]

@@vigilantcosmicpenguin8721 Rather than use a highly accurate clock, the powers that be decided we would use the WWV time ticks as recorded on the strip chart to get “accurate’” timing to correlate the PMT data. The time of day was recorded as text in Morse code and each second was a mark on the strip chart…yes, they really designed the system this way…

[@googleyoutubechannel8554]

Yep, the continual story of 20th century junk scientists caught in the loop of 'wash-your-back', constantly churning out 'peer reviewed' p-hacking...

[@timothyodonnell8591]

Dr. Becky- thank you for taking the time to explain the paper and the context in easy to understand, plain English. You are a credit to your profession!

[@PopeGoliath]

With data that messy it's no wonder at all that statisticians were able to massage it to fit four different theories.

[@TacticusPrime]

Hey Dr. Becky, what's the most distant object that GAIA has been able to resolve the direct distance to using parallax? I heard that it was able to view much further than ever before. I haven't seen it posted anywhere.

[@derekwood8184]

Thank you Dr Becky and I totally agree with your skepticism. The trouble with saying "you can just average the data" to get a result.. is that you might have more of one angle of inclination or eccentricity that will bias the results. You might also have "split lots" (production engineering term).. That's when you have two seperate statistical sets (with different averages and spreads) sitting on top of one another, depending on the ratio of type A/B your average will shift.. it's why I'm extremely dubious about pushing data substantially beyond the accuracy of the initial data in a scenario like this, only when you know you've got just one class of data can you start pushing averages. I don't buy it yet.

[@bacca71]

As my grandpappy the physicist used to say, "There's lies, damned lies, and statistics." While often useful, statistics and probability can be easily misapplied. Or from the other direction: 'The Fine Art of Pounding a Square Peg into a Round Hole.' Keep up the informative presentations!

[@dewiz9596]

So, your grandpappy was channeling Mark Twain?

[@bacca71]

@@dewiz9596 Yes he was, exactly! There was a New England connection. With cigars.

[@davidevans3227]

i thought you were going to say.. "...and there's physics..."

[@Retinetin]

Hi Dr. Becky! I actually just read an article that sounded very similar but had yet of course ANOTHER theory, but it's a bit different than the other papers. They actually specifically call out and compare MONDian models with theirs because their model fits even better than MOND-like models. Their model uses fractional calculus because they believe that the effects of gravity can have a non local effect. One of the only ways we can model this mathematically is with fractional calculus, because unlike normal calculus, a change in the graph somewhere actually has an effect on the rest of the graph with fractional calculus. It's extremely intriguing and hope to get your thoughts on it! DOI: 10.3847/1538-4357/acc8ca

[@highgroundproductions8590]

Interersting.

[@skateboardingjesus4006]

​@@highgroundproductions8590Intrirguing even.

[@leoilling3061]

@@georgejacobs5782but a modified theory of gravity would no longer be able to have a vector that points to the center of mass. We can see that galaxies will orbit around seemingly empty space. Thus we conclude it is dark matter. How would a change in the direction of gravity work?

[@aretwodeetoo1181]

​@@georgejacobs5782Precisely. That 5/6ths of "matter" is invisible IS the extraordinary claim...

[@geesehoward700]

MOND and MOND-likes dont describe what gravity is though unlike GR and so they feel like a step backwards just to get rid of something that we dont like. doesnt feel very scientific.

[@Darth_Q]

I'm not a physicist. I don't think I know more than those that have studied physics just because I watch a couple of youtube-videos every week. I understand that the lambda-CDM is the best model we have to explain the observations (even if I don't comprehend a fraction of it). I certainly don't have a better theory. That said, how can we say that Einstein has never been proven wrong when some of the predictions of the theory of general relativity obviously give other answers than what we observe? We need to invent/stipulate/postulate 4 or 5 times the mass we see in order to explain the observations like the galactic rotation speed and even more than that to explain the expansion speed of the universe. Is this just semantics or what am I missing?

[@DNPaterson]

Non-Newtonian gravity has been an interest of mine (as an amateur) for quite a while, and this is a really good review of current thinking in the field. I've heard talks by both Indranil Banik and Hongsheng Zhao, and by the sound of it this new paper may be a significant move towards solving the puzzle. At the very least it could reduce the uncertainty about dark matter and the options for alternate theories of gravity. Research in other areas has shown there may well be some deficiencies in Einstein's model, so setting limits on the range of these would be another step towards a better understanding of it.

[@456steve]

Dr Becky! Thank you so much for your videos, you have inspired so many people including myself to realize that their interest in Space and Astrophysics can be more than just that. I recently accepted a job working on a Telescope network at a university while also participating in research as an undergraduate at my university. Your channel has shown to so many people that fundamental questions that we have about Space and Time that strike out at us so intrinsically can be more than just a hobby, and I want to thank you for that and I look forward to more of your videos.

[@christopherlewis1847]

Best wishes to your great career! May you discover many wonderful things!

[@DrBecky]

Wow Steve, this is so lovely to hear! I’m so glad I could play a small part on your journey. All the best with your studies and career

[@vladimirmihnev9702]

Great thing to hear. Good luck and may you have a long and productive work life in this wonderful field of science!

[@MichaelSiegel14]

I remain skeptical. MOND has always been a bit ad hoc, especially after the Bullet Cluster results made it impossible for even MOND to function without some amount of dark matter.

[@yevgenchuk]

You dont have to explain bullet cluster. You have to find out explanation. Good luck.

[@pjaworek6793]

The bullet cluster, galaxies without dark matter...so easy to state, why do we need videos or papers that don't address these?

[@derekborigo8601]

I love how you always approach these controversial theories with a scientifically open mind.

[@nihlify]

MOND aren't even that controversial

[@landsgevaer]

@@nihlify Or, one might prefer to argue that dark matter is controversial too. In the sense that there is controversy, lack of consensus.

[@justinwalker4475]

she is a scientist !

[@justinwalker4475]

o0

[@justinwalker4475]

theories .you mean life the universe...everything in it? take time out ponder think muse

[@Brainfryde]

Should be interesting, but Dark matter theory is also equally extraordinary in terms of its claims. I would never suggest the Newtonian / Einsteinian models are not superior to all other models today, but this is more due to a net value of zero when it comes to high accuracy data. I will wait and see what exactly these two hypothesis end up creating for potential theories where none of the proposed elements are 100% theoretical! Until then, popcorn doesn't hurt anyone :) Thanks for the brilliant translation as always!!

[@StanleyDevastating]

dark matter has a lot of different lines of evidence that all support it's existence. MOND doesn't.

[@aliensarerealttsa6198]

Physicists/sociopaths: "we have no idea so we're going to agree to call this phenomenon darkmatter (and antimatter, et al) to explain away our dunning kruger effect." Instead of admitting that they're wrong by sounding like illiterates who use oxymorons to explain and imply incorrectly.

[@oberonpanopticon]

@@aliensarerealttsa6198ah, a brilliant entry into the “say you have no idea what you’re talking about without saying you have no idea what you’re talking about” challenge. also, are you trying to say antimatter doesn’t exist? I mean skepticism of dark matter as a particle I can understand given the lack of detecting it, but we’ve been working with antimatter in labs for decades now and it’s quite thoroughly explained by the standard model…

[@oberonpanopticon]

“Dark matter” is literally an admission that there’s something out there we don’t understand. Dark matter isn’t a specific new particle or theory, it’s a blanket term for theories that propose new physics to explain the difference between our predictions based on the known laws of physics and our observations of distant galaxies.

[@aliensarerealttsa6198]

@@oberonpanopticon I'm saying that saying "antimatter" is a stupid term only used by sociopaths and psychopaths to describe matter with a different charge (anti matter). Anti matter is matter. What I said before was the equivalent of what you said in a prior post. I'm not sure why you're confused by the logic that we both agree to, and instead you get offended by it because you lack basic reading comprehension? Maybe try empathy instead of an emotional response. But yeah, antimatter doesn't exist. It's a word used by illiterates. The proper term is counter particle(s). Also, annihilation. Another word that proves how incompetant all physicists are.

[@startrek0336]

The limited internet research on dark matter I've done a while back for a school project left me wondering on one part: the correlation of visible light to mass, which is used to create the expected rotation curve. There was one paper, though it was only on arxiv, that proposed a way to estimate the mass distribution in the galaxy with the star density distribution from GAIA data. The rotation curve created that way matched the observed rotation curve.

[@stoatystoat174]

I love GAIA. Its crazy how much we don't get about our own galaxy

[@chrismaggio210]

Thanks, Becky. It remains one of the main mysteries that I hope gets solved in my lifetime! Great update.

[@robbierobinson8819]

Thank you for explaining these papers so a biologist can understand you. I really look forward to the Bayseian analyses but in the meantime, have a query about the analyses so far done on the Gaia data. Not unexpectedly, there is a drop of in numbers of pairs at the greater distances. By eye, it does look as though this is having undue effect on where the fitted lines are drawn. Have the distances been divided into classes and data been randomly sub-sampled so each class has the same numbers of star pairs and the subsets used for fit?

[@heliosophist334]

I can't thank you enough for taking the time to produce these videos. Looking forward to your future coverage on this important subject. All the best!

[@goalieben20]

I suck at math, so a lot of the deep dive into these topics goes over my head, but even as a layperson, the idea of dark matter has always rubbed me the wrong way. It feels to me like we're probably just wrong about something. Bottom line: I love listening to you explain things.

[@1FatLittleMonkey]

That's the problem, we're all innately biased against dark matter. (And I mean all. Even dark matter theorists tend not to be as hostile to the alternatives as non-DM theorists are to DM. Instead, they're just sort of resigned to it.) But DM just keeps working. MOND theorists end up, as with the work in the video, faffing around in the statistical margins, chasing shadows in a snow storm. I always wanted MOND to be correct, so I used to get excited by every hint that it was real, because variable gravity means new physics (which maybe means our SF future is possible.) But these days, whenever I hear that a MOND advocate has published the Big Thing! that This Time!, Totally proves MOND for Realz!!!11!, I tend to yawn and assume that it will fall apart on closer inspection. It's never aliens. It's never FTL. It's never New Physics. We aren't that lucky.

​@@1FatLittleMonkeywhy is there no dark matter close to us?

[@-_James_-]

@ I guess the argument there is: There is, but we just can't see it. (Or detect it with current technologies.) We perceive matter as particles, which (according to my understanding of quantum field theory) can be considered as peaks of energy within a quantum field. But the rest of that field isn't flat - it's constantly fluctuating (which is what gives rise to virtual particles - again if I understand things correctly), so those fluctuations throughout the known universe will add to the overall energy (or mass in the case of the Higgs field) of the universe - but just in a way that we can't directly measure. (I think. 🤷‍♂)

[@1FatLittleMonkey]

@ What makes you think there isn't?

[@karlkarlsson9126]

I feel the opposite. The more I look into the ideas of it being wrong, because I was feeling it in that way as well, the more I see that dark matter actually is a matter of some sort. But I do want it to not be any kind of matter.

[@dworkin7110]

Dear Dr. Becky.. Love your videos and your ability to put across complex subjects in a straight-forward way. Please don't stop!

[@liftpenguin]

I did my bachelor thesis on mond and Zhao was my supervisor! Shoutout H.S

[@duckyjp17]

Skeptical of whether dark matter exists. Yep. I’m in that camp. Fascinated to watch this unfold.

[@teaser6089]

Any scientist should be skeptical, cause it makes no sense, it's truly one of those moments where some scientists follow math too much, just because it makes the math look more beautiful, doesn't mean it is reality. Dark matter is one of those cases where the math dictates what we should observe, but physics is about making math that describes what we observe, dark matter in and of itself is against the principles science and physics are build upon. Instead of realizing that GR doesn't fully predict what we observe in the universe, some scientists put Einstein on the pedestal of a god like creature that couldnt possibly have made a mistake(something Einstein wouldve found very funny) and start adding numbers to the math to make the math work again and now trying to find those numbers in reality, without having any reason to assume it actually exists. It has never been observed, so there is no reason to assume it exists. Dark matter is the physics version of a Unicorn, they are assuming a unicorn exists, even though no one has ever seen one. But the lack of evidence very rarely is evidence.

[@Justpooinabush]

​@@teaser6089I think you're doing a slight disservice to the physicists who research this complicated field of cosmology and you're making it sound like the pursuit of knowledge in this realm is entirely driven by ideology or some sort of faith based motivational reasoning. The truth is that physics is absolutely littered with examples of models predicting the existence of a certain particle, force or interaction, with no prior observational evidence, only to then be confirmed by empirical data. I think the lack of evidence in this example shines a light on how difficult this problem really is more than anything else...

[@stanleydodds9]

@@teaser6089I think you are forgetting that GR works extremely well, or in fact perfectly, in a large variety of situations that we can observe. So there is good reason to think that GR is at least some way towards the "correct" description of gravity. It's not just that GR looks nice - it also works very well in practice. Secondly, it's not like people are pretending that GR is definitely the final answer and that we are just looking at the universe wrong. We know that GR is not the final answer, because it is not compatible with QFT for instance. But it is by far the best description of gravity, space and time that we have at the moment.

[@teaser6089]

@@stanleydodds9 I mean I agree that GR works a lot of the time, but when it doesn't, the right move isn't to invent math tricks to make it work again and then try to invent object that will make the math work. No the math should describe observation and GR doesn't always describe the observations, which means the first move is to change GR into an equation that does describe what we observe. Now scientists are spending billions of tax dollars hunting something they actually have no proof of it actually existing, basically hunting for the physics version of an unicorn.

[@teaser6089]

@@Justpooinabush I mean I am oversimplyfing yeah. But to counter the models predicting certain particles, the standard model of particle physics does not predict nor need the existence of dark matter, so I would counter that in this case nothing is actually predicting dark matter, cause dark matter is added as a number in the math to make GR work again, but just because the math works now, doesn't mean the math is actually describing reality anymore. If Einstein was still alive today he would have probably been very amused by the entire situation.

[@uteriel282]

not sure im on board with this new model when its accuracy isnt even 10% of the data sample. with major variables missing you can interpret the findings in whatever way you want which makes it nothing but guess work whatever mond is accurate or not. also if they change how gravity works depending on the distance of 2 orbiting objects from each other why not change the unknown parameters as well untill something usefull comes up then observe those objects again to see if it fits with reality? cause at this point they just picked the results that support their ideas while disregarding the rest. needless to say this doesnt prove nor disprove anything at this point.

[@johannesalexandersen7323]

Does the curvature that a massive object creates in spacetime "flatten" instantly when that object moves away? Or does it act in a more "viscous" manner? Like pulling a spoon through water vs pulling it through honey? What consequences, if any, are there for how we understand gravity? 🤔

[@thechickenclub3801]

Thank you for your scientific and unbiased review of this paper, and look forward to the next instalment. I am also glad you have finally managed to get a new ring light. Many thanks for great work

[@shubinternet]

Hmm. Is it a ring light? I'm seeing two separate highlights in her eyeballs, neither of which is ring shaped. I agree, the lighting does look good. But I'm not convinced it's a ring light.

[@DrBecky]

It’s two soft boxes this time! I feel very fancy

[@derekking7319]

@@DrBeckyLoved your enthusiastic explanations on the theories gaining popularity! But I do have a question which is gravity related. What is the “Great Attractor” and how does it affect the models for a universe with no dark matter in it? Thanks again.

[@russellbarndt6579]

Your excitement about what it is we don't know and cannot completely calculate the answer for an 100 % acceptable theory is what would bring me to your class every day if my circumstances were at all different...

[@richardmercer2337]

... not to mention hers...

[@SpeakerWiggin49]

I'm excited to see that Bayesian Statistics analysis of the data. If it is going to take that long to publish, I have high hopes for the quality of the paper.

[@indranilbanik3424]

I am leading this study and currently working on the revisions requested by the referee, but also folding in several other improvements that the authors came up with. The basics are shown in this video: kzbin.info/www/bejne/pJ3LnpKLlrl_hK8

[@williamotule]

I doubt it will give a clearer answer, just another one

[@indranilbanik3424]

@@williamotule My article will also address what was wrong with the claims to confirm MOND.

[@definitelynotofficial7350]

​@@indranilbanik3424So what do you think of the future of MOND after this?

[@indranilbanik3424]

@@definitelynotofficial7350 There is also a very severe problem for MOND with galaxy clusters, which on a logarithmic RAR diagram follow a parallel track to the line of equality but offset up by 0.8 dex (Arxiv:2303.10175, see fig. 5). That is just what you would expect if there was 6x as much mass as the baryons, which is the LCDM prediction not informed by the clusters in question (it is based on the CMB at high redshift). But the problem for MOND is that the data extend down to quite low accelerations, so that clusters are observed to have less gravity in their outskirts than predicted in MOND. This is opposite the problem in the central regions. Only substantial amounts of negative mass can solve the problem (Arxiv:2205.01110, see fig. 8). These results indicate that the gravity law is inverse square in the low acceleration outskirts of galaxy clusters, where MOND should work just fine and the gravity is still stronger than plausible external fields. Combined with the wide binary results, it is clear that MOND cannot be extended outside the galaxy scales for which it was designed. The situation for MOND is bleak. I do not expect to work in astrophysics at this time next year.

[@ethorii]

Dark matter being taken so seriously as a new particle is rash and I'm surprised so many physicists are sure its real without any evidence outside of unexplained gravitational binding in galaxies and some lensing behavior

[@jarirepo1172]

I don't have background to claim to know much of this, but I have for a while felt like dark matter does not feel right explanation... We can only observe the gravitational effect but not the reason. Unless we really find out what dark matter is I think it's more likely there's more to gravity than our current theories predict. But what, where and how, I have no idea.

[@maxplanck9055]

Much love Becky, fun to learn about science in an informal conversational way ✌️❤️🇬🇧

[@247tubefan]

Is it possible that regular gravity just behaves with varying values over galactic distances?

[@nihlify]

that's what mond basically is

[@Drummerx04]

Is it possible? Sure. Is it reality? We don't know yet lol. We can imagine all kinds of random guess, but making actual predictions and then proving them scientifically is quite difficult.

[@me_fo]

I love hearing you explain these concepts! Thank you for making this kind of science accessible!

[@DrBecky]

My pleasure 🤗 glad you enjoy it

[@madeleinebirchfield7658]

@@DrBecky You never linked the Triton Station blog in the description that you said you were going to do towards the end of the video.

[@Deano-Dron81]

@@madeleinebirchfield7658Look it up yourself, I’m sure you could find it with a few basic searches. Why do people need to have everything at their fingertips now adays. Just try to search it yourself, it can’t be that hard….

[@jean-micheljantke9275]

Dr. Becky, thank you for this video about gravitation theories and their predictions vs the present observations. Have you ever made a video about the JANUS model ? I would like to have your point of view on a model where mass of matter (and therefore energy) may also be negative, now that we have computers that can run simulations (as you suggest for application of MOND theory to binary systems). Anyway, thanks again for this presentation of the diverse papers, and your explanations about the missing data about the values of eccentricity and inclination for these binary stars systems. It helps to understand the difficulty for "proving" gravitation theories ! ;-)

[@wayneyadams]

I really appreciate the links to the papers mentioned in the video, especially since they are free as opposed to so many papers that cost outrageous amounts of money for digital copies. They charge us an arm and a leg, and they don't even have to print or mail anything. Thanks Dr. Becky. There is some sort of obsession (almost a mild psychosis) in certain people that drives them to try and disprove the work of Einstein. Both his theories of Relativity, plus the consequence that no body with mass can travel at or above the speed of light are prime targets of their obsession. We need to be skeptical of these wild theories that have alternate explanations of physical phenomena based on sketchy interpretations of data. Here is a personal anecdote to explain why I am so skeptical of theories like this. In one of my graduate physics (Cosmology) classes I wrote a paper using research that refuted the expansion of the universe. The researchers had compelling evidence to support their theory and they had published numerous peer reviewed papers. 5:23 Orbits of TWO bodies around the center of mass are 2-dimensional, so why did you say 3-dimensional measurements? 6:45 Orbits that are perfect circles are very difficult to obtain given the very strict velocity requirements, that is why most orbits are elliptical which encompasses a wide range of velocities and therefore much more common. 7:42 Interestingly, as the velocity goes down and the separation increases, the error bars expand significantly. 8:51 Don't forget that this is a logarithmic scale so that small separation is not really that small. For example, 10,000,000/10 = 1,000,000 while log(10,000,000)/log(10) = 7/1 = 7. This is a point I always had to stress to my students when we graphed results using logarithmic scales. 9:30 Wow! 10-sigma far surpasses the accepted 6-sigma threshold. 11:00 This is nothing more than good old fashioned conditional probability. What is the probability of B given A, P(B|A). 12:00 If the paper is in the referee process how can you predict that it SHOULD be out by the end of the year? You can't confidently make that prediction it could very well be rejected.

[@zblurth]

I think a video on how sigma are "assigned" / determined could be really interesting, so sigma are simple to understand like if a interne was assigned to flip a coin ten thousand trillion time you would get your 10 sigma statistical significance but on even we do not have that much data or much of the date is uncertain how do you scientifically determine the probability of the event.

[@DrDeuteron]

The way you do it is to fit you model to the data wrt to the MOND parameter, and then change that parameter until chi-squared goes up by one. That is 1 sigma. With more than one parameter, you can do a principle comment analysis to remove correlations. Ofc, you need error bars on your data, which we don't see, but they would make a log-log plot look like an ink blot. In the purely modeled data, you know the exact answer, but you can add random numbers to the simulated measurement to figure out your sensitivity.

[@alphalunamare]

If you live in a World where it is acceptable for an intern to be set the task of flipping a coin even 10,000 times then you have less than a one sigma level of confidence in understanding your own question.

[@RossMaynardProcessExcellence]

A physics video that is very well presented, (almost) understandable and actually funny (at the end) is quite an achievement. Good work.

[@johnzuijdveld9585]

I'm an observer with no comparable knowledge, but the impression I get from the comments is that as far as the science allows the video is 'actually understandable,' funny as that may seem!

[@Jezee213]

I'm one of the "Dark matter isn't real" camp. Either way though if it's real, amazing! If not, amazing. Just to have a definitive answer would be game changing! I think it's something missing in the laws or measurements.

[@kmbbmj5857]

Either way is great. If it's real, then we have problems with our understanding of other theories. If it's not real, then we have problems with our understanding of gravity. What a fun time.

[@dewiz9596]

Indeed. The distance ladder has a few broken rungs

[@oberonpanopticon]

I mean there’s a pretty enormous amount of evidence that dark matter is SOMETHING. The only other alternative is that an enormous number of our methods of observing the universe are flawed.

[@FrostW1nd]

The bloopers is the section I enjoyed the most!!! Thanks Becky!!!

[@multivariateperspective5137]

Excellent job, and funny! The song at the end was great that you had to clarify “it’s dark matter singing” BwHahaha… multiple meanings are usually fun

[@busomite]

I’ve been waiting to see if you’d make a video on this, thanks for such an in depth review. This is the scientific process playing out before us!

[@harrymills2770]

I remember the contortions they went through to force-fit the geo-centric cosmology with observations. That's been my intuition about "dark matter."

[@allansouth5889]

I agree, though my parallel is with the "aether" that was supposed in the late 19th century, to be necessary for light to propagate. The Michelson-Morley experiment put paid to that idea.

[@jamescole322]

Or Planet Vulcan to explain Mercury's orbit anomaly before General Relativity

[@Commander_ZiN]

Personally I've been leaning more towards mond even before I knew about it. I just saw the lack of progress in finding particles before even the higgs was found and though maybe the math is wrong. I didn't realise at the time there was a whole theory about this since before I was born. Edit: correction - not long after I was born. I really do get confused why they focus was more on one theory over another. Shouldn't they put a reasonable effort into all likely theories? How do they determine what is more likely?

[@morningmadera]

Maybe you should do some research on where MOND fails before you make this "theory" your belief on reality.

[@bensemusx]

Watch her video on dark matter. The two theories are not at all on the same level. She herself supports dark matter over MOND.

[@Commander_ZiN]

@@bensemusx I've seen the dark matter video, I've seen lots on both subjects. I don't know why you set your sights on one, when neither are confirmed and both are plausible. I've not seen anything on either that leads to more credence to one or the other, I just feel they would have noticed something by now. She herself is still open to MOND, why aren't you? How is dark matter on a different level? I've seen a lot of theories on what dark matter could be, none seem any more plausible than MOND to me.

[@uteriel282]

@@Commander_ZiN mond at this point is just guess work that picked a small portion of the overall sample size which agrees with its notion. could it be plausible? maybe. is it anywhere accurate enough to actualy use it? not realy.

[@Commander_ZiN]

@@uteriel282 none of what you said is true. It's no more guess work than dark matter. It is accurate enough to use which is why they're able to make predictions with it. If it was as bad as you say, they wouldn't be entertaining the idea. This behaviour is exactly what I don't understand, why do people cling to one theory over another when both are plausible? It might be different in all the years of searching they actually found some evidence of dark matter but they haven't. Wouldn't it be better not to ignore the other theory? Einstein isn't infallible, I don't know why people avoid questioning his work. MOND should be looked into until it can be ruled out, following all possible paths to their conclusion the only thing that makes sense. It's better than focusing on one that yields no results.

[@neilhollands2750]

Being a layman as I am, I have no theory of gravity… But I have to say, believing that the universe is mostly matter we can’t detect simply because our theories of gravity can’t accurately predict movements on the largest scale… seems like the most extraordinary claim. A theory like some form of MOND seems much more plausible. We simply don’t know what gravity is.

[@dsnodgrass4843]

Awesome that you find Dr. McGaugh's website of value! I know him, and he's a highly gifted explainer of both LCDM and MOND; as well as being very honest and transparent about the process by which his inclination changed from one to the other. A lot of it's way over my head; but many smarter folk than i would benefit from hearing him out on the topic.

[@SidIcarus]

There are areas where MOND's predictions haven't been as successful. Unlike General Relativity, which predicts everything perfectly.... except for when it doesn't and you just add these invisible, undetectable particles wherever you need them, in whatever quantity you need them, until the math works out again.

[@drdca8263]

That’s not really a good description, I think. The way that dark matter is believed to be distributed isn’t just, “some arbitrary distribution to make it work”. It has dynamics, and the way it is believed to be distributed, is in accordance with how it it is believed it would naturally end up being distributed if it did exist. Now, if it were literally just an arbitrary field that could have whatever constant values would produce the seemingly observed gravity, then that would be a whole lot of extra parameters, and therefore a very strong reason to doubt the theory on Occam’s Razor grounds, but that’s not the kind of theory that the theory is. It isn’t much additional description complexity to posit “there is another field which starts out being uniformly distributed, and then evolves in accordance with gravitational interaction”. And as for it not being directly observable, I don’t see a reason that our priors should assign a particularly low probability to “there being a lot of mass that we can’t see directly, on account of it not interacting electromagnetically”.

[@bensemusx]

You have no idea what dark matter actually is. She herself supports dark matter over MOND. Go watch her video explaining what dark matter is and why it’s the leading theory.

[@zackyezek3760]

@@drdca8263he’s actually less wrong than you’d think. Look up all the problems and hand waving that are actually needed to make dark matter models (mostly) match the data. You need nebulous “feedback” to wave away issues like the cusp-core problem, or explain away empirically observed patterns like the Tully-Fisher Law and Radial Acceleration Relation. WIMP dark matter particles have largely been ruled out experimentally, in terrestrial direct detection experiments, and axions’ tiny mass plus ability to convert into photons in strong magnetic fields already puts serious observational limits on their ability to provide all this supposed missing mass. And this doesn’t even factor in dark energy, an even bigger and more mysterious fudge factor necessary to explain how the observed motions of whole galaxy clusters are consistent with general relativity. The simplest explanation is that GR breaks down for extremely weak fields and extremely large distances. And this shouldn’t be shocking; it’s already expected to break down for ultra strong fields like black holes.

[@pauljs75]

One question to ask, is would one rather put their hand between two magnets the size of bowling balls that are a few feet apart, or non-magnetic objects the same size? Such forces didn't just simply disappear because of differences in scale, but it seems datasets and models are making the assumption that they did. The dark stuff is likely making up for things we already know about, but for whatever reasons left out of the equation.

[@shawn2736]

Dark matter is an observation, not a part of GR. The Bullet Cluster and the observed gravitational lensing is a good example of how DM has been indirectly observed.

[@grantgussie8768]

You presented very clear thinking and an understandable analysis. Bravo. And I also have a hard time buying the "statistically significant" claim, let alone the claimed 10 sigma result. Off hand I can't think of ANY other stats-based paper that claimed a 10 sigma result.

[@neon1899]

So basically Dr. Becky is saying, we're far from solving dark matter vs MOND debate

[@bensemusx]

Not really. The data used by this team has been used by others that reached the opposite conclusion. Even if this paper is right it doesn’t actually disprove dark matter. It just reduces how much there is. Dark matter is way more than just fixing galaxy rotations. Go watch her video on dark matter to get a better understanding of it.

[@neon1899]

@@bensemusx Yes I have seen that video. The case for dark matter is definitely stronger than MOND as of now, but all I am saying is, it'll take a bit longer to actually settle this debate.

[@yevgenchuk]

​@@bensemusxDark matter does not exist. Tully Fisher's law contradicts its existence. There are gravity formulas, after measurements the researchers found that there is no match between the formulas and the observations, so they added mass to make it match, and called this mass dark matter. And who said the formulas are correct? In short, this whole theory is cheating, period.

[@neon1899]

@@yevgenchuk it's not "cheating". The need for dark matter exists to be consistent with theory of general relativity. If dark matter doesn't exist, general relativity is wrong. And it could be wrong, but it has been proven way more times than MOND has. Unless MOND can improve on general relativity, I am in favour of dark matter

[@yevgenchuk]

​​​@@neon1899This does not mean that the theory of relativity is wrong, it means that it is a special case of something a little more general. Remember that in the formula proposed by German Mankowski, Einstein's math teacher, there are three dimensions, and time. Time is written like this: time multiplied by the speed of light, which is units of distance. There is a minus there, and we don't know why. All this implies that there can be more than one direction of time, or 3 directions of space. I will tell you a secret, Dr. Dmitry Pavlov developed a theory of four dimensions of time and space. And did three experiments that showed that events affect time. It looks like an extension of relativity, but it's not exactly. In any case, Newton is a special case of relativity, so relativity is a special case of something else. Everything is simple, and scientific. You just have to get out of the mindset of "we know everything", and then everything will start to work out. Continuing the search for dark matter is definitely a tragedy for science.And in fact Tully Fisher's law, contradicts the existence of dark matter, because it links visible mass to speed. And the speed there is in the 4th power, which reinforces the idea of ​​extending the theory of relativity which is in the 2nd power. From the formulas of Dmitri Pavlov, there is a fit for the graphs of rotation speed of spiral galaxies. But more interestingly, the formulas explain MOND theory. To remind you, Mond is a solution without explanation.

[@Stroheim333]

Look at it like this: _Neither_ GR or MOND must be correct, but MOND is pointing in the right direction. As Hendrik Lorentz anticipated Einstein, but never got all the details right. Remember that there is not even an explanation for the behaviour of gravity in MOND, it is pure ad hoc.

[@karijuleppanen]

For those GAIA data I could draw a line in almost any direction, forgetting the units used. I don't see any correlation at all! I'd say that an almost horizontal line (slightly ascending) would fit the data set the best. Why a descending line? And then, what logarithmic scale was used? In my math classes, lg was used for Briggs logarithm, 10-based; ln for natural e-based logarithm; and log for everything else, where you'd had to write down the base number. Those lines in that data set don't make any sense at all. Could you elaborate. Btw. I love your channel, Dr Becky!f

[@jajssblue]

I love how digestible you make these technical arguments.

[@Drrobverjones]

It has always been strange to me that the most accepted theory is one that requires you to add stuff that isn't observed (dark matter).

[@davidh.4944]

As opposed to the ones that require you to make adjustments to universal parameters that aren't observed? Frankly, it's the duck principle at work. If it behaves like some form of matter (if a bit oddly), it most likely _is_ some form of matter (if a bit odd). Might as well look there first, and then expand your search if necessary.

[@pansepot1490]

Dark matter is just a label (perhaps a not accurate one) for an observed phenomenon. It’s not that we can’t see it, it’s that we don’t know what it is.

[@dewiz9596]

Before Copernicus, this was called “epicycles”

[@Drrobverjones]

@@pansepot1490 the problem is that we say it exists only because we assume we have the right theory. If your axioms are wrong, then the results are wrong. We don't observe dark matter. What we observe is that our assumptions of how gravity works seem to suggest more mass than there is. And not just a little bit, but a ton more.

[@Drrobverjones]

@@pansepot1490 it's observed in the sense that our axioms say it has to exist. The point of the alternative (mond) is that perhaps our axiom is incorrect. If our assumptions are wrong, then the results are also wrong. If we can't "observe" dark matter, and it only exists because of our math makes it exist based on what we see, it seems that perhaps we should rethink our axioms.

[@roy1701d]

10 Sigma seems...bold. Almost absurdly so. But I'm no astrophysicist, so what do I know. Still, my gut tells me that MOND (or some version of it) is closer to reality than dark matter. As always, we need more data, and more tests. Another great video, Becky. Thanks!

[@pansepot1490]

Nah, with thousands of astrophysicists working at it for decades, if it was just a matter of tweaking Newton gravity someone would have come up with a decent model years ago.

[@busomite]

@@pansepot1490The same could be said for explaining dark matter, that we’d have some sort of breakthrough in 6 decades. Dark matter is a mathematical explanation without observed explanation. It’s akin to string theory in this way. The model fits because it was built to fit the known data. And yet, it’s still the best explanation we have so far. I’m encouraged that there are people pushing to find explanations since there hasn’t been a breakthrough on dark matter.

[@bensemusx]

I highly recommend watching her video on dark matter. There’s a reason she and others put dark matter and GR above MOND.

[@Knirin]

⁠@@pansepot1490Do they have a working version of MOND that deals with Mercury’s orbit, gravitational lensing, and time dilation. Those three items combined make for very strong evidence that gravity is a side effect of some form of geometric effect not a dynamics problem with funny changes in the dynamics at different scales.

[@roy1701d]

@@bensemusx I have seen that video. I'm fine with dark matter theory; if it's proven correct, then that's fine. But as I said, my GUT tells me that dark matter overcomplicates our cosmological model, and that it seems more likely that we're missing something. (Again, I'm no astrophysicist, so what do I know.) 🙂

[@raminagrobis6112]

I'd wish all scientific presentations would end with a bloopers session. Hilarious!!😂

[@danlindy9670]

If you have solid evidence to support an extraordinary claim, should you dismiss it because it is not extraordinary?

[@JackToTheA1]

Thanks for this video!!! This is very interesting and i love that you’re open to different theories. I want to be more open to different ideas and Im glad you explain them so well. Also have i finally found someone who loves space AND taylor swift as much as I do 😂😂

[@LaserGuidedLoogie]

I love this video; excellent run down of the 4 papers. I'm one of those who hate DM, and I love that contenders are now being seriously considered instead of summarily dismissed, but I do love the drama in this field. It's going to be interesting, no matter what.

[@rich1051414]

I can only hope more interest is put into finding a solution that works at all scales now that people are seriously considering that dark matter may very be nothing more than error manifest.

[@Fearthelettuce]

Every time I hear about dark matter, it seems like someone just made it up to fix a problem. Like sticking a book under a table leg. It's insane to me that it has become mostly accepted with no actual evidence

[@moesheen654]

Same. I was thinking (and in no way claim to be a scientist) that as string theory says gravity is not tied to one universe as other forces are, perhaps dark matter is gravity created from mass in other universes and may account for the so calledadd of dark matter. So I looked on the internet for this hypothesis and found forums with people arguing that this was impossible for all kinds of reasons and I thought, why has everyone dismissed this thought experiment yet dark matter is so widely accepted with seemingly no better evidence. As stated in this video, extraordinary claims require extraordinary evidence, and both of these thing seem to fall into this category in my very humble opinion.

[@rosomak8244]

The idol is the big bang. They warship it.

[@AnonymerVIP]

Well, I see two problems with this Idea. First, the force of Gravity decrease with the distance squared 1/r². Masses outside of our visible universe are way to far away to impact gravitationally the rotation of a Galaxy e.g. in our galactic cluster, the force would be negligible. Second, things outside our own universe are not observable. It would be impossible to experimentaly check if this is really the case. The reason why Dark Matter hypothesis getting more attention is, that often they to solve more than one problem. Some of these particles could explain the galactic rotation curve and solve a problem in particle physics, so researchers from two fields would be interested in that if one can find it.

[@StanleyDevastating]

it was thought up as a potential solution to one problem. and then it kept solving different problems. there is a lot of evidence for it and that is why it is currently favoured by most astrophysicists.

[@moesheen654]

Ok. lots of mathematical evidence sure, but how do they decide how much there is? Calculate back from what makes there calculations work? I understand it's complicated but if it's unprovable, or so far unproven, it makes sense to look into other solutions, otherwise it's like saying all the patterns I see point to a designer. Maybe it does, but we can't find them.

[@aretwodeetoo1181]

Thanks for the update. The extraordinary claim is that 5/6th of matter is invisible (emphasis on the word matter)... That our present equations for gravity are probably incomplete is just highly likely given the history of science and should be assumed.

[@mickelodiansurname9578]

While I think there is definitely something that does not add up with the whole stuffing of dark matter into the problem of missing baryonic matter... well the whole MOND thing is also something that also either doesn't add up, or when it does you get a different answer every time. I was in uni when this was first touted and at the time it sounded absolutely crazy. From my perspective the fact its now being considered tells us just how wrong we must be with both dark matter and Newtonian solutions.

[@sdwone]

To be frank, I've always had an issue with so called Dark Physics. This idea that approximately 96% of the Universe is "missing", because certain observations don't fit certain theories. And to add salt into this wound, we still haven't reconciled Gravity with Quantum Mechanics... Assuming that they even can be reconciled! So not only do our own observations baffle us, we don't yet have a complete theoretical framework, which might shed new light on the matter. So yes... This is all very much a working process... Aka Science! And until we can conclude something definitive, I wouldn't place any bets just yet! Anyway ALL the answers are out there... Somewhere! And until we become interplanetary so that we can build even more sophisticated instruments, I suspect those answers won't be forthcoming for quite a while! There's really only so much we can do down here... Stuck on this speck of a rock!

[@alphalunamare]

I don't think that we have to go interplanetary to open our minds and revisit our dogma. Physics today is as if under The Spanish Inquisition. If you want funding then don't rock the boat. Even an idiot can see that Physics today is in a crisis but you dare question its foundations and you are burned. Physics today lacks the ability to look inwards and reconsider. Certainly the purported constancy of Constants over epochs of time is poorly understood.

[@jackwilson5542]

Well said, if the theory needs 97% of universe to be made up off stuff, there is 0 proof of existence thereof it is likely that the theory is wrong. Problem is throughout history people were always c*cky thinking they knew it all. Whether it was firmament, geocentrism and today relativity, there is always dogmatic thinking, rather than rational. If we want to reach the stars (both figuratively and literally) we need more open minded people in science coming up with new theories. Otherwise we are gonna be stuck on this piece of rock until it is destroyed in one way or the other.

[@AthiktosOfficial]

I have always had an interesting thought on gravity. We treat it currently as a tug on space time around it. But I had a thought about how gravity itself may be defined by type of "frictional" field that isn't necessarily just this tug on space time, but more so a fluid that's pulling on matter based on the amount of energy that is concentrated in an area. Unfortunately, I'm not really capable of doing the mathematical side of things, that's in the future, but I felt that would be something I should share. Hope ya see it.

[@xochilguevara3429]

I’ve always been skeptical of dark matter, but it would take a whole lot to disregard Einy.

[@neon1899]

Exact same here

[@Davey101_]

The thing is, general relativity is already imperfect in that it fails to work at quantum scales. To me, the usefulness of MOND is to explore the other areas where it doesn't agree with observation. We can try to fill the gaps left until we have a relativistic theory of everything, without inventing particles and packing them in arbitrary ring distributions.

[@xochilguevara3429]

Agreed

[@xochilguevara3429]

Except that I don’t see general relativity as flawed, just not all-encompassing.

[@bensemusx]

@@Davey101_MOND doesn’t get rid of dark matter. Dark matter has grown beyond just fixing galaxy rotations. The leading theory to explain the universe is Lambda CDM or Lambda Cold Dark Matter. All MOND does is reduce the amount of dark matter needed now.

[@Kanner111]

I am extremely bullish on alternative gravity theories in general (or basically anything that gets rid of Dark Energy and all of the associated weirdness of universal anti-gravity fields), but also claiming a 10 sigma result on anything is pretty much the fastest way to blow up your credibility, let alone when you're fitting a line to a shotgun blast of dots. That's just using maths to say 'I'm right, don't argue with me, I'm right'. =/

[@jamesrumsey]

One thing that puzzles me is that you can't measure the angle of the stars you're looking at, and you can't tell what their orbital path or "eccentricity" is, and yet you jump to the insane conclusion that there's something called "Dark Matter" that is completely invisible on all wavelengths and would pass through a brick wall as if it wasn't even there. Did you ever think that maybe you don't have any idea what's actually going on?

[@hazel-rah4997]

MOND... Yeah no.

[@macupie]

1:11 Nooo! MOND is the moon! (at least in my language...) :D

[@luudest]

haha!

[@TheJimSkipper]

Einstein’s theory of gravity is completely accurate if you invent an imaginary, undetectable substance to fudge the equations.

[@jacobhatfield4970]

Yes it works 99 times out it of 100. No one has come up with a better idea yet. This is how all the theories around the atom first worked people tyres to fit experimental data into already known theories

[@williamotule]

Ok but would you put Hernandez's work changing his mind on par with Chae's? Same question for the other ones. And referring to the abstract Pittordis and Sutherland concede that they need to assess more data. What you are saying about Bayesian statistics is completely confusing. I did not get your point, what are the prior and posterior here which will change the game? I can't grasp how this paper coming out soon can eventually discern between the two alternatives differently than by a frequentist analysis. I mean both MUST give the same result asymptotically...

[@timbennion7079]

Very interesting video Dr Becky. (A very silly,, tiny point but I was interested that you pronounce either as I-ther as opposed to ee-ther, more typically used). I have always pronounced that word as you do (sort of satisfying to hear you use the word in that way). Anyway I stray from the point of your video...... an extremely interesting and well explained complexity in all the research and theories pertaining to our attempts to fully understand or explain dark matter.

[@lady_draguliana784]

to me, I find it heartening that at least one of the involved parties is rapidly flipping their opinion based on the data as it develops: it seems to suggest to me that they're not biased, and are following the Data more directly.

[@kirkpetersjr]

Really quick.. How do we explain the bullet cluster? I don't think MOND has ever held up. I'm not for either idea MOND or Dark Matter, but we need data and proof.

[@planexshifter]

Dr. Becky getting shout outs from PBS Space Time. Talk about a mark of success. Thanks for the knowledge!

[@louisroberts4089]

Is there any effect on the way a binary systems orbit by the gravitational waves produced by the bodies themselves ? From what you explained the idea was to use a binary system to see if the observed behaviour would be explained by 'tweaking' the gravitational constant. But the missing bit would be 'why' this is the case. I was wondering if the gravitational waves produced would in themselves be a possible cause. When ever we get a demonstration of way bodies orbit - we get shown the trampoline with a bowling ball and a smaller object orbiting around the curvature. But if the bodies cause 'vibrations' within that curvature, would that change the behaviour ?

[@Jesse_359]

Rather hoping for MOND to come out ahead. While I don't have a problem with Dark Matter in principle, the open-ended nature of its variables and the inherent extreme difficulty of testing it makes it an unpleasant solution in terms of our ability to ever come to grips with it, even if we were to agree that it were the correct answer. MOND, if it is proven, would have the advantage of being a far more straightforward and testable physical description of the universe.

[@billyshinbone8908]

Thank you for this, yet another of your thorough yet clearly presented videos. I'm not from an academic background but the way in which you communicate your understanding of complex scientific research makes the broad subject of astrophysics accessable to someone like me. Thank you very much.😊 One thing though - I think you mean "alternative" theories rather than "alternate" theories. Alternate means taking turns. Alternative means different from. Huge respect & admiration for you & your work.

[@GregorShapiro]

When data is 'binned' it can be grouped in different ways, could selective binning prove or disprove the (or any given) hypotheses?

[@Mike-zx1kx]

Be open and hang on! If I allow myself to zoom out a bit I sometimes think that there are to much focus on Einsteins relativity theory while forgetting Bohr´s Quantum physics. If we assume we are part of a multiverse and we accept Einsteins relativity theory are real but HAVE limitations then what role do quantum entanglement/Quantum theoretic´s possibly play? Could there be some built in constants that are totally undiscovered and thus could be an integrated part of more dimensions than we currently can prove? If we for a moment allow ourselves to assume/accept that we ARE being visited by other beings and we assume/accept their manner of travel in the dimensions we are familiar with, that defies our knowledge and we return to speculations of "bending space" and similar theoretic´s for explanations we have to then also assume/accept the probability of anti gravity and/or ability to protect these beings inside the crafts from these forces in their "outerworldly accelerations, speed of travel etc. If we remember that we at CERN have proven scientifically that subatomic particles slows down and greatly improve living length more, as particles gets close to the speed of light and thus, proven, behave radically different in that situation, should we then not have greater focus on exploring Bohr´s theories and their possible implications in space/multiverse with focus on quantum entanglement and the real possibility that some of these processes might have some sort of "constant" or scientific rule-set that we are blind to (inside a certain spectrum)? I "buy" the curvature of space/time objects cause but could there be a another rule-set/dimension aspect that are linked to quantum entanglement/Bohr´s theoretic s (That we have to remember are being practically proven to be true now) we only now begin to realise via the CERN results? Maybe this rule set only applies in a certain spectrum, as we see things actually scientifically proven behave much differently close to the speed of light? Analogies are sometimes great to paint a picture so here we might could use the picture that we live in a reality of a 100 kilometres road but it are only 3 metres of that road that are rifled and only in those three metre span will we experience that our tires sing and car are shaken while we still move forward despite wheels only momentarily touch asphalt....-ish. If dark matter ARE the majority of space then maybe its the other way around and we currently are understanding the 3 metres and the rest are the unknown for us in reality? Personally I think we should use more resources in investigating the narrow field where we now have scientific proof reality behaves significantly different than in our everyday 3 dimensional world. Worth remembering too that theoretical mathematics often seem to give more "clear numbers" when incorporating especially 2 different numbers of dimensions. The deeper our proven knowledge gets these years the more the different scientific fields approach each other. The theory of "everything" might be for just one spectrum while new "worlds" might have its own theoretic´s and aspects we now only are beginning to open the door to. It will be easy to make comments to the above shooting at it but could we please try to buy into the possibility and thus explore the possibility instead in comments? That might bring aspects to consider as we step into the newly opened door. Could Bohr be the key in this century as Einstein were in the last?

[@_moonandtosaturn]

You sang exile in the bloopers!!!! Ahh my heart is content 😊 Also love your content!! It's so easy to understand.

[@rkirby7183]

This is probably wrong, but I've always wondered if the discrepancy in orbital velocities at the edge of galaxies might be due to what might be called "local gravity". For example, does the standard model assume that a galaxy exerts gravitational force from its center according to its total mass? If so, might not the gravity of the nearest 100 stars--or 1000--exert a noticeable influence beyond what's expected due to their proximity? For a star on the edge of the galactic disk, this influence would be to increase the expected force toward the center. Then this influence would decline as you moved inward on the disk by 10%, 20%, etc. since now the exterior stars would begin to equalize this influence. Admittedly, this would be a small gravitational influence but the gravity from the distant galactic center is also small.

[@xyzpdq1122]

The preview pic for this one was hilarious 😂

[@davidseed2939]

what is the orbital period. will eccentricity and inclination be better determined with a longer period of observation.

[@excrubulent]

So the falloff in gravitational strength is an inverse square for a long distance, after which it's slightly stronger than you'd expect. Given the typical explanation for the strength of gravity is that of a field diminishing in strength as it expands through space, could this be explained by saying the universe is slightly spherical, rather than perfectly flat? I know the current MOND shows two straight lines, but the analysis of the 10-sigma result would've been comparing one straight line vs the two pictured. A spherical universe would I assume give a long, very slightly curving line instead.

[@karen23826]

If I’m understanding this correctly the averaging does this but wanted to check. Is there a way to control for the most likely distributions of inclination and eccentricity in the data? I’ll admit my area of expertise is in medicine. But I know there have been multiple studies on these two variables in planetary systems, but don’t know if there’s been any studies on multi star systems or if that’s even feasible or how valid it would be to assume these findings would be the same for the binary systems that fit the mond parameters. Thank you for your time.

[@arrau08]

Thanks a lot for a great review. I'm just a lazy astrophysicist in Korea and felt the need to catch up with this subject, but that 10sigma claim kept putting a mind barrier whenever I tried to read the paper.

[@user-zz6fk8bc8u]

10 sigma is ridiculous. This claim alone is just such a red flag the paper basically has to be BS.

[@Gantics-Antics]

Why would the force of gravity be weaker at lower velocities? Is it just that because we think we might be observing this that we are testing or is there an underlying mechanical theory? Sorry im a newb at physics.

[@oakbellUK]

Forgive me if I'm just uninformed, but, at very low levels of gravity from the objects under consideration (eg the two binary stars), is there not a significant effect from other objects further away? One could imagine an object becoming effectively weightless due to background gravity all around.

[@anthonywhitney634]

So General Relativity has passed every test that's been thrown at it. Except when it didn't and dark matter was invoked to explain discrepancies. That's a bit of a blind spot, Dr Becky.

[@Askey-vo7fp]

Thanks for the video, but just one question: If you have the 3D position/velocity from the GAIA data, why can't you calculate the eccentricity and inclination?

[@BeAndNBovee]

I heard Doctor Becky mention position/velocity, but not "3-D...". I'm guessing the sensitivity to changes in brightness magnitude were insufficient to record the movement in 3-D.

[@YouthTheBand]

Is inclination angle uniformly distributed or is it correlated with galactic plane?

[@Equiluxe1]

I recently read that Newton wrote in Latin and there are a number of errors that have been made in the translations, dose this have any bearing on the problem or are we going to be left with dark matter, which maybe should be called magical matter as it cannot be seen,felt or measured but still manages to affect whole galaxies.

[@ariuskahn3419]

There is no Dark Matter. Stars on the edge of a galaxy are also affected by the tide of the Electro Magnetic field generated from the core of the galaxy. It looks like it should be a gravitational effect but it is not.

[@Thoringer]

Yes, these Bayesian algorithms don't always converge. You may have to run them several times, tweak your predictions... interesting stuff - and the reason my personal workstation has 128GB RAM. And running some mortality data inferences took hours to run in R.

[@MrJdsenior]

What does for or against even mean? I just watched a video of the guy who was instrumental in proposing dark matter, and his thought was, creating a million theories is fine, but then test to throw out what doesn't fit, when you can create an experiment to do that. He also pointed out that one thing that worries him is all the "we'll get to it later" bits that have never been gotten to, in the rush to push things forward, and that some of those answers might push current thinking in other directions. It was hosted by the Ted Talks guy, Brian, but on his YT channel, and came out very recently, the last few days. It was an excellent interview. As I understand it, the problem with just tweaking Newton doesn't address a whole plethora of the other very real observational reasons that dark matter was put forth, at all.

[@Robustacap]

How much does the "speed" of an object effect its gravity? Spin/rotation etc. It is after all space-time, time being related to causal actions. Yeah, I'm a total layman and just trying to understand. Also, any thoughts on the concept of "Tired Light"?