"getting mogged" now has a compeletly new meaning lmao

@Robert-er5wq

26 күн бұрын

You mean Reese-Mogged?

@AndrewB383

26 күн бұрын

Brutally mogged

@cakeboss921

26 күн бұрын

she's even mewing in the thumbnail

@jprin8429

26 күн бұрын

Was abt to say this lol

@BenjaminGoose

26 күн бұрын

Is it some weird furry thing you're into?

A video on the different theories of modified gravity (MOND, MOG, AeST, Oppenheim, etc.) could be informative. Describing what each looks like mathematically/physically and what each gets right or wrong about observational data.

@JK_Vermont

27 күн бұрын

Yes, and I'd also want to understand which ones are more and less easy to fit to data by cherrypicking free parameters.

@SabineHossenfelder

27 күн бұрын

That's an interesting suggestion, thanks! I'll keep that in mind.

@SubparFiddle

26 күн бұрын

Gotta at least mention Electric Universe :)

@unoriginalname4321

26 күн бұрын

​@@SubparFiddlegotta walk down to electric gravi-U

@nishantyadav8184

26 күн бұрын

Hey how is this comment 23 hrs old? The video was uploaded just 29 min ago!!

In the movie “Spaceballs”, John Candy’s character was from a race called Mog(half man-half dog). He was his own best friend.

@scotthammond3230

26 күн бұрын

John Candy was everyone's best friend.

@cohenworrior898

26 күн бұрын

Aren't we all . . .

@agweis

26 күн бұрын

"Ahhhh, when you're right, you're right, and you, you're always right!"

@nuance9000

26 күн бұрын

In the Final Fantasy series, Mog is a famous moogle, generally with a gold pom pom

@yeroca

26 күн бұрын

@@scotthammond3230 Him and Chris Farley.

imagine aliens scared of us when they pick up among our broadcasts mentions of Modified Gravity Wars

@piotrrashman6487

26 күн бұрын

"they're doing WHAT to gravity? oh, we're not going anywhere near those lunatics!"

@lamaspacos

26 күн бұрын

😂😂😂😂😂😂

@user-om1pp5qe5z

26 күн бұрын

IF there were aliens they would look at our technology and wars and laugh at us primitives

@randar1969

3 күн бұрын

lol that's funny thanks for the laugh i needed it

@randar1969

3 күн бұрын

@@user-om1pp5qe5z Or even conclude there is no intelligent life on Earth..

John Moffat taught the course in gravity that I took at U. of T. I liked him as a teacher and liked the subject, though not enough to go into the field. Nice to see him pop up here.

@kierana.carroll672

26 күн бұрын

I TA'd his 1st-year physics course at UofT, many years ago, and so was always interested when I saw occasional news articles about his theories about a possible "fifth force." Later I invited him to come give a talk at our local Space Society, which he graciously did, on the topic of MOG. Which he explained so well that a room full of non-physicists came away with a reasonable understanding of its main elements (though I think I was the only one in the room to go on to read his papers on the topic, and try to decipher his extensions to GR!). He's a novel thinker, and a great explainer.

We all just got MOGGED

@thrwwccnt5845

26 күн бұрын

Mewbine Moggenfelder

@GeekOverdose

26 күн бұрын

@@thrwwccnt5845 🗿

@lupin8876

26 күн бұрын

fr

@ToothSocial

26 күн бұрын

I can't help but understand / believe MOND. It seems like space is kinda like a waffle-pattern robe that also acts like broken ice on a pond. It just is

@ToothSocial

26 күн бұрын

​@@lupin8876shoe fits - wear the mf

It's the gremlins, they modify gravity when you aren't looking and change it back when you are looking

@altrag

26 күн бұрын

Probably. They already do it for the other fundamental forces :D

@DreadDeimos

25 күн бұрын

MOGwai, perhaps?

When Sabina is in her 90s will she still be saying,"Dark matter, if it exists, which it may not."

@Thomas-gk42

26 күн бұрын

Or she has the Noble then for hear own theory

I never thought I'd live to see the day Sabine mews and mogs on camera

@thrwwccnt5845

26 күн бұрын

Mewbine Moggenfelder

@ConnorisseurYT

26 күн бұрын

@@thrwwccnt5845 i hereby revoke your youtube comment privileges

@pauljs75

26 күн бұрын

@@thrwwccnt5845 I think I'd be willing to watch a Vtuber that had that as their character name.

@pugasaurusrex8253

23 күн бұрын

@@thrwwccnt5845one of the finest rizzicists of our time

@dunzek943

19 күн бұрын

All of us zoomers came out of their mother's basement to comment just this once for this moment

The main issue I have with relativistic modified gravity is that they tend to add fields, at which point is not different to dark matter, only that MOND fields are free parameters and dark matter can in principle being detected, although with great difficulty. I should add that the main allure of dark matter comes from the idea that there should be relic particles from when the Universe have a phase transition when initial symmetries were broken. This is still the case as Higg boson detection confirms the electroweak unification. The only issue of dark matter is when people say is fact, when is just a working model that needs further experiments, which is ok.

@TooSlowTube

26 күн бұрын

The main problem I have with gravity is the idea that it's a field. Show me the grass. Show me the hedges. They can't.

@altrag

26 күн бұрын

> at which point is not different to dark matter Ehh there is a small difference, though it may be (perhaps likely is) entirely conceptual. A field without a particle meshes with the ideas of QFT (and thus the standard model) a lot nicer than a particle without a field would. That doesn't necessarily make it more "correct" (and it still wouldn't be a theory of quantum gravity... probably) but it might make it more palatable to some scientists and researchers. 80% being confident in some form of dark matter is still leaves a whole lot of very smart people looking for alternatives. And there's always the possibility of something like an M-theory breakthrough where someone discovers that the particles of dark matter theories are actually excitations of the MOG fields and that the theories are fundamentally equivalent. Still doesn't make it "correct" (string theory hasn't displaced anything yet and is not even really considered a TOE candidate anymore) but it could lead to some interesting and useful mathematical insights that can be applied elsewhere.

@bjornfeuerbacher5514

26 күн бұрын

@@altrag "A field without a particle meshes with the ideas of QFT (and thus the standard model) a lot nicer than a particle without a field would. " Huh? According to everything I know, both possibilities don't work in QFT. When you have a field, you automatically have particles, and vice versa.

@RotsorKG

25 күн бұрын

Sabine did mention at 6:30 that the difference between MOG and Dark Matter is that the former doesn't consist of particles, but that seems like an irrelevant detail to me: if you've accepted the existence of *some substance* that's distributed independently from normal matter, you've thereby accepted Dark Matter.

@danieljensen2626

24 күн бұрын

MOG doesn't involve any substance, it just changes the math for the gravitational field produced by ordinary matter.

Wow, excellent! Dramatic like a thriller, how it flips forward and backward. Good to have someone who keeps us up to date!

Dear Sabine, Shakespeare also a favorite wrote: I don't pick my wisdom from the Stars, but I think I understand Astronomy.. Sonnet Number 14

This explanation of Mog sounded really strange. It comes across like we just formalize the observations using math. Not like it provides some deeper insight beyond an additional set of rules we just follow and then the math works. I would really like a deeper explanation of how this theory goes beyond just formalizing additional rules.

@MassDefibrillator

26 күн бұрын

It's funny you mention this, as this is exactly what Newtons description of gravity was, and he knew it. He said: " to derive two or three general principles of motion from phenomena, and afterwards to tell us how the properties and actions of all corporeal things follow from those manifest principles, would be a very great step in Philosophy, though the causes of those principles were not yet discovered." The causes of those principles were not explained by newton, the implication of his mathematics of "action-at-a-distance" was "so great an Absurdity, that I believe no Man who has in philosophical matter a competent Faculty of thinking can ever fall into it." according to him. When newton came along, there were already very good descriptions of the motion of planets and objects on earth. What he did was to unify them, (though his mathematics struggled to find many testable applications), with a new formalism, that did not even attempt to explain the the causes of what was observed. This new mathematical paradigm was then just internalised, and it itself now is considered the explanation. Or, another way to put it, those going into modern physics looking for physical interpretations of the maths are going to be disappointed. At best, your lecturer will tell you there isn't any physical interpretation to the math, at worst, they will give you a misleading analogy.

@RokeJulianLockhart.s13ouq

26 күн бұрын

Indeed. It seemed like that should have been the principle point of the video, and yet was lacking.

@mikehannan8206

25 күн бұрын

The best answer I have found is in Ray Fleming’s book “The zero point universe”. He also does podcasts.

@lexer_

25 күн бұрын

@@MassDefibrillator I understand where you are coming from but I don't feel like that is a fair comparison. The difference is that newtons new formula is far simpler and easier to work with. It simplifies the problem into a universal relationship between parameters. But Mog seems to be different. It's more like newton but imagine he had added a nonlinear smoothing function that regulated gravity based on speed to get the terminal velocity and to explain why an object stops speeding up but only for falling things on earth. To be fair its fairly obvious that this is due to friction with the air but I am just trying to create a (unfortunately tortured) analogy here. Like instead of explaining anything you just take the part you don't understand and push it somewhere else to quote the famous philosopher patrick star.

@danieljensen2626

24 күн бұрын

For physicists the math is all that really matters. 🤷‍♂️ For example, there are like 20 different interpretations of what quantum mechanics "means", but all of them agree on the math, so it doesn't matter that much. Sabine admittedly didn't even explain the math here, but it sounds like "there is a scalar and vector field and those cause gravity". For comparison, electricity and magnetism can also be explained in terms of a scalar and vector field. If you work with those fields enough you can develop intuition for how they work just as much as you can with other ways of expressing the math.

Moffat has written several books for the general public. I recommend Reinventing Gravity. You don’t have to be a professional physicist to understand it. Also Einstein Wrote Back - My Life in Physics about his encounters with legendary physicists. For a good read about the Higgs check out Cracking the Particle Code of the Universe: The Hunt for the Higgs Boson. P.s. Moffat is 91 and still publishing impressive stuff like this most recent paper.

It's always entertaining to see the discontinuity of hairstyle between the body of the video and the ad at the end. Lol

@drwagner14

25 күн бұрын

hairstyle?

Kudos to the Perimeter Institute for supporting approaches that are less 'mainstream'. That doesn't mean they are automatically more likely to be correct, but they do expand the search area for theories to explain inconsistent data.

@ika5666

26 күн бұрын

They rather support "their people", a "crony science" if you want, and Moffat was in the business of his MOG in Waterloo long before the PI was even opened 25 years ago or so.

Moffat seems to have a very interesting view on the Higgs as well, could be interesting to know more about his theories 😊

I was smart once. Read it all and kept up to date with science news. but my work is of the heavy kind in the steel industry. And i am getting old. 43! My free time is spent on working on the household and drinking beer. my IQ is dropping in a steady rate. I think it's ok. I will never change the world. The youthful vigor is exchanged with patience. I'm growing more introverted for every year that goes by. I'm ok with this. I'm finally mellowing out. I do not need to be smarter or better than anyone else... I'm coming out to you guys! I'm an average Joe now. and I love it. Thank you for listening!

@DesertRat332

25 күн бұрын

Yup. Same here. I'm about 30 years ahead of you.

gravity modified 3 of my ribs a week ago when I introduced it to 'big tree branch'

4:28 : it’s the modified theory of gravity whack-a-mole. They just keep cropping up again once the data or model is adapted.

@Abluemoon9112

26 күн бұрын

Except this has been around for 20 plus years

@Vastin

26 күн бұрын

Much like the veritable zoo of particles posited as dark matter candidates. Both approaches have the problem that they can be adapted to fit data as needed - at least until we hit one that is accurate enough that it no longer needs to be adapted because it finally fits all of our available high quality data, or until we actually detect and confirm the existence of one of the dark matter candidates - unlikely given that in order to function as described they have to be essentially undetectable.

@Anton-tf9iw

26 күн бұрын

The Modern Physics Emperor has no explanatory cloths in the huge gravity/matter field: groping in the dark. Thanks for enlightening us on that Sabine!

@altrag

26 күн бұрын

That's kind of what GR does too. GR is a very, very loose framework and the simplest solutions certainly don't apply to every situation. There is certainly _some_ nicety in that you have a framework at all (so you just need to come up with new solutions to the equations rather than new equations) but at some level its still just plugging holes whenever something new shows up. And that's not really a bad thing. Every theory needs to be tweaked whenever something new shows up - that's how science progresses. When things work very well, somebody will notice a pattern to the tweaks and be able to derive a more universal theory from them, but that's not strictly necessary and is definitely not strictly necessary within any given period of time. It took 400 years for Newton to be displaced by Einstein. There's no reason to believe that displacing Einstein will happen within our lifetimes.

To explain the odd shape and motion of galaxies, why can't we look at them as whirlpools in a lake with invisible currents? You have to admit that those whirlpools (in lakes) can look mysterious, as if perpetuated by an invisible hand that stirs them.

@altrag

26 күн бұрын

That's exactly what dark matter does. The whirlpool idea with only visible matter doesn't match observations (look up "galaxy rotation curves" for more info). Dark matter was added to be more "water" in the whirlpool and that fixes the rotation rates to match observations. Modified gravity is also the whirlpool idea in a sense, but it says that very large whirlpools (galaxy-sized) whirl faster than more moderate whirlpools (solar system-sized). Neither theory produces any explanation for the "invisible hand". That's more of a philosophical question that science almost certainly won't be able to answer until we have a confirmed theory of quantum gravity, and possibly not even then (can't really be predicted as we currently have absolutely no idea what the true theory of quantum gravity will look like never mind analyzing any limitations it may have). Of course the "invisible hand" for real water-based whirlpools is gravity, but we can't say gravity is causing gravity as that would be a bit too self-referential :D.

@JZsBFF

26 күн бұрын

@@altrag Thanks for sending my comment in a more educated direction.

@altrag

26 күн бұрын

@@JZsBFF One more thing to keep in mind is that the whirlpool (and the rubber sheet and whatever else people use to try and explain this stuff) are all 3-dimensional analogies to a fundamentally 4-dimensional phenomena (complex dimensions to boot). Experiments at both the very large (telescope observations of space) and the very small (particle physics) have confirmed the idea that space and time are connected, and that the 4-dimensional concept of spacetime is correct (or rather, we can't have less than 4 dimensions - more than 4 is still on the table, but that only makes the problem worse!) Unfortunately that means no analogy we can make or arguably even imagine with our 3D-expecting brains can even in principle be 100% accurate. The math can handle it just fine but our intuition often has trouble keeping up.

Dang Sabine, you are prolific.

@manjsher3094

26 күн бұрын

Playing the algorithm

If gravity has a speed limit, an object is basically pulled by another object where it was in the past (possibly a long time ago). Thats pretty important when we talk about thousands of lightyears in distance. How come this is not part of MOND in the first place?

@martijn8554

26 күн бұрын

AIUI it's more complicated than that. When the gravity of a star reaches you it pulls you more towards where the star is than where you see it in the sky. Like it has a sort of lateral movement based on the speed the star is moving at. So the speed of light limit of gravity doesn't really work the obvious way.

@Currywurst4444

26 күн бұрын

The distance might be thousands of lightyears but the objects need millions of years to travel that distance so the effect is negligible.

@fritzbloedow29

26 күн бұрын

If I understood the results correctly, LIGO showed that gravity follows speed of light rules when we saw the two neutron stars merger with LIGO and telescopes, the signal arrived at almost the same time over very long range.I seem to remember something about neutrinos also being detected, but i may be wrong. MOND doesn't have speed of light limit because Newtonian physics doesn't, it was never going to be the final equations because of that, just a model to start looking in the right direction, unless you decide to replace General Relativity all together.

@traumflug

26 күн бұрын

Gravity over thousands of lightyears of distance isn't exactly strong. Also, as heavy objects move with much much less than lightspeed, the direction of pull changes only marginally within a couple of years. Such gravity variations are likely hard to measure/observe at all, so having it in the equitation or not makes no measurable distinction.

@MatthewHolevinski

26 күн бұрын

The human race is still yet to prove that gravity even exists, so it could just be a specious discussion.

Could this be something to do with dark energy, not dark matter or modified gravity? Maybe when objects are closer together dark energy is repelling them more strongly but when they’re more isolated the repulsion is less and the attraction of gravity appears to be greater when compared to masses that are closer to other masses?

@randar1969

3 күн бұрын

You said "Maybe when objects are closer together dark energy is repelling them more strongly but when they’re more isolated the repulsion is less" Then my question to you is why do we see galaxies drifting apart then? There are just a few atoms per square meter between galaxies, way less even then any isolated star? And why we don't see any stronger repulsive force from for example Sgr A* and surroundings?

I just watched the last two videos over dark matter and modified gravity on this channel. What a roller coaster!

if i only could remember the name of the youtuber that always told me the main issue of modern theoretical physics that once the data does not fit the predicition they don't give up the theory they just add more parameter it would then fit the data. If i only could remember...

@sydneyvogel8121

24 күн бұрын

This also, In my opinion, applies to dark matter though. Like, they looked at an instance where the current math isn’t working and said “okay, so there’s some completely invisible answer undetectable substance here, that must be why the current math is failing” which is really frustrating honestly because it’s not even something that can ever really be disproven unless someone proves another explanation. I’d be happy just to know the answer, in all honesty, but as of now I think people are putting WAAAY too much emphasis on dark matter. We should be exploring (and funding) a myriad of different theories and approaches, that way we can at least narrow it down

@angrymokyuu9475

23 күн бұрын

@@sydneyvogel8121 I think the big issue with dark matter is, despite insisting it's just a historic name for an unknown, the term really has bottled people into thinking it must be a particle of some sort - with the corollary that, if there's no particle, then there must be an issue with gravitational theory. There being an alternative source of gravitational attraction(such as the mass of a galactic-scale electromagnetic field, to pick an amusing example) seems to be almost entirely unexplored.

I wonder if saying "I don't believe in dark energy" would annoy astrophysicist even more Specifically "I don't think the cosmological constant has to be made of anything and therefore saying it compose over 70% of the universe's energy is disingenuous"

@trucid2

26 күн бұрын

The fact that Lambda CDM needs inflation, dark matter AND dark energy is a huge red flag. Three different effects that we have no evidence for.

@ObjectsInMotion

26 күн бұрын

That "therefore" is not logically sound. In fact, most physicists believe dark energy *isnt* made of anything *and* composes 70% of the universes' energy. Energy can be intrinsic to spacetime itself.

@ten-hx2xi

26 күн бұрын

THIS is the kind of scalding tea i want, tysm❤

@hugegamer5988

26 күн бұрын

Thinking and belief don’t factor in at all. It’s observation and how the math of accepted theory works. The effects are measurable and real, you might as well try disbelieving in gravity to fly.

@ObjectsInMotion

26 күн бұрын

@@hugegamer5988 they do matter, because physicists tend to believe what there is observational evidence for. In fact, when it comes to models, you can only have belief. The facts are black and white but you can't observe an interpretation for those fact. A theory is a model which must be constructed *from* observed evidence but can never itself be observed. Theories are abstract constructs that only exist in the minds of humans that are a only a reflection of reality. Therefore, thoughts and believes absolutely do matter when it comes to interpretations that have equal evidence (or lack thereof) behind them.

This is really exciting for me, because I remotely understand what it is about. And, I allways liked Astronomy !

My problem with all these things (modified this or that, dark matter) is they seem to be very ad hoc, they give off epicycles vibes. Just tweak the theory in certain somewhat arbitrary ways to fit the data. Great, it fits the data, but it also seems a bit post hoc.

4:34 time permitting, you could explain why some people thought it acceptable to neglect relativistic effects

Thank you for the video.

As Tuvok's* actor once said: "We ain't found shit" From Star Trek Voyager*

Fascinating! Thanks, Sabine! 😊 Stay safe there with your family! 🖖😊

Sabine, thank you so much for looking into Moffat's MOG and making this video!! He's got quite a story. Brilliant.

@ika5666

26 күн бұрын

What is brilliant in modifying general relativity in just one of zillions possible ways...

important to keep an open mind

Oh thank goodness somebody is looking at this in a non-silly way. First, starting from a theory you know is wrong is just silly. Second, distance/time makes way more sense to look for something being dependent upon than low acceleration. Third, not pursuing it because the math is hard is just lame. We know GR is a tensor theory and is the most accurate one we have… so trying to solve this mystery using scalar math just seems like high school level work. If you’re going to upgrade our best tensor theory, you don’t do it using a scalar approach unless you solve it in tensor space and a simplified scalar solution pops out (which seems unlikely). Moffat is my new cosmology hero.

@jakeaurod

26 күн бұрын

I've heard lots of physicists claim that a theory should be simple, elegant and beautiful, hence the low complexity mathematics.

@Z0mbieAnt

26 күн бұрын

@@jakeaurod I don't do physics, but as a computer scientist "Keep it simple" is always the go to approach. But at any point you should be ready to leave the simple solution behind if it doesn't solve your problem. You can write the most elegant and beautiful theories, but in the end if they aren't correct they are worthless.

@byz-blade

26 күн бұрын

@@jakeaurod -- a theory should be as simple as possible, and no simpler. Having simple theories is not useful if they are wrong. e.g. "gee, it sure seems like the ground is flat, so I theorize that the whole of the Earth is flat".

@cerad7304

26 күн бұрын

We also know that Newtonian gravity is wrong but we still use it because, well, quantum gravity is still not a thing. Cosmologists are just support to wait around until those quantum people get their act together? Edit to maybe clarify. Yes GR comes into play for high gravity. My understanding is that Mong deals with low gravity hence there is no real need to assume that GR plays a role and thus it would make sense mathematically to start with Newtonian gravity. Long live the Mongs.

@FredPlanatia

26 күн бұрын

@@cerad7304 erm, no we use Newtonian gravity for everything where the gravitational field is weak. however the orbit of mercury shows behaviour that deviates from newtonian gravity because mercury is quite close to the sun and there we use general relativity and it works perfectly. We don't need quantum anything for that. Even all our data on black holes is (so far) consistent with general relativity.

Is there no connection between MOND or MOG and gravitational lensing phenomena?

@SabineHossenfelder

27 күн бұрын

Gravitational lensing generally isn't particularly good at telling apart modified gravity from dark matter, and I don't expect it to be good at telling different modified gravities from each other. The issue is, in a nutshell, that the best-fit parameters to gravitational lensing images have very large uncertainties. You can almost always find something that fits somehow.

Really interesting! Everything that gets us away from this magical thinking called "Dark Matter" is a win for science!

Alexandre Deurs Self interaction in GR seems similar to mog. It considers the different degrees of isopropy of a system along side its mass. From this the length scale found in the radial acceleration relation fall out naturally as at larger radii you exit the isotropic bulge. It’s all rooted in GR as well!

According to wikipedia, MOG can't account for the Bullet Cluster. Ethan Siegel is referred to. Sabine Hossenfelder, on the other hand, says MOG deals just fine with the Bullet Cluster. Should the wikipedia article on MOG be supplemented or corrected? en.wikipedia.org/wiki/Scalar-tensor-vector_gravity

@bjornfeuerbacher5514

26 күн бұрын

There is only mention by a blog post by Ethan Siegel, he didn't actually publish this in the scientific literature. So I would take his argument with a heap of salt. :/

@atlantisvelforening

24 күн бұрын

John Moffat and Norman Israel discusses The Bullet Cluster and MOG in this paper (from 2018): arxiv.org/pdf/1606.09128.pdf

I love Sabine 😅 ❤️

Another new idea floating around today that passed one test is the use of tachyons to explain away dark matter and dark energy. Interesting.

@altrag

26 күн бұрын

Trouble is that's even less testable than dark matter and has the "benefit" of introducing some pretty big complications to the standard model. We certainly shouldn't rule anything out if the math appears to work, but it behooves us for purely practical reasons to try the things we have some hope of confirming or denying before putting too much effort into the more esoteric ideas. Occam's razor and all that.

Good one Sabine! This is a tough one. Black holes play into this as well. If spacetime is bent inward that has to have a profound effect on gravity. Not only at the event horizon but throughout the galaxy.

@OMDMIntl

26 күн бұрын

If something becomes a singularity then something else must go to infinte

Why should Dark matter be thinly distributed? Suppose Dark matter has immense density but rather it's gravity coupling is weak. If it doesn't couple at all electromagnetically with normal matter I don't see the necessity for it to have total coupling with gravity.

@bjornfeuerbacher5514

26 күн бұрын

"Why should Dark matter be thinly distributed?" The distribution can be actually determined from the rotation curves of galaxies etc. "Suppose Dark matter has immense density but rather it's gravity coupling is weak." That doesn't make sense. The mass of a particle is essentially identical to its gravity coupling.

mogged by sabine

If you do a back-off-the-envelope calculation of how much Dark Matter is in the Solar system using very simple assumptions, you get to the mass equivalent of a 200 km asteroid.

Off topic, I just wanted to say thank you for your videos Sabine. They really clear up a lot of confusion for those of us who are not physicists but really enjoy learning about the field.

You say, "Dark Matter," I say, "Invisible Elves." Pretty much the same.

@MyName-tb9oz

26 күн бұрын

Our observable universe is some alien high school kid's science fair project. Cut it some slack. It doesn't have the best equipment and galactic rotational rates are hard. Sheesh.

@EnlightenedMinarchist

26 күн бұрын

Lol. Wtf. Absolutely not. We have observed dark matter halos

@MyName-tb9oz

25 күн бұрын

@@EnlightenedMinarchist: ========> Joke:You:Joke

danke! super interessant!

Dear Sabine, thank you reminding us what scientist should be "open minded skeptical data based". Too many devote their entire being to theories and their theory becomes their religion. They lost sight of data and supporting evidence and become dogmatic and close minded. Love your videos and hearing your views.

Thank you John.

Have we ever observed gravitational effects that show the dark matter is off-center of some galaxy due to galaxy collision or something? Such an observation would quite clearly show there really is some unseen stuff in space.

@fandomguy8025

19 күн бұрын

Yes, actually, the bullet cluster, though MOND proponents & those who build off it like those that work on Entropic Gravity respond that space time isn't immediately elastic. (Paraphrasing a quote I can't find currently unfortunately) The rare anti-dark matter observer will also point to Abell 520 the "Train Wreck Cluster" which goes against the implications of the bullet cluster/dark matter, & is much lesser known.

Hi John! Love you & what you do, big guy🎉

Sabine, please clarify one point for viewers like me (non-physicists). The discrepancy on the star velocities on the periphery of galaxies is with Newtonian dynamics. I know it is nearly impossible to solve Einstein's field equations for a large number of bodies but has anyone tried to solve them for a toy galactic swarm to see if the discrepancy with Newtonian dynamics disappears due to general relativity effects?

6:25 Scalar+ Vector- This is why math is weird, we don’t use this in the number system. (-1 0 1 2 3 4 5 6 7 8 9 10 11) for a 13 Prime number system. You still get base 10, so the only changes are in the inclusion of the Vector- and not just the Scalar+. -1 + 0, it’s the Vector moving towards the Scalar and that is the progression of time, the movement of the Vector allows for the progression of gravity as the Vector pulls back on the Scalar. (-1) 11+-1=10 (0) 10+0=10 (+1) 10+1=11 (+2) 11+1=12 (+3) 12+1=13 (+4) 13+1=14 (+5) 14+1=15 (+6) 15+1=16 (+7) 16+1=17 (+8) 17+1=18 (+9) 18+1=19 (10) 19+1=20 (11) 20+1=21

Sounds interesting, like it'd mesh up with that crazy idea of mass being the relation of an energy density gradient vs. the background properties of free space. And the forces associated with that relationship, such as gravity, happens to be some kind of tensor curl effect. If you allow for certain direct substitutions into equations Einstein did, it works out. Even if it drags some of Maxwell's stuff back into it. (May not be the "aether", but spacetime apparently has odd hysteresis properties to it. Things that could be considered as springiness or a dampening/drag effect.) Weirder yet, is that if spacetime can be proven to have a measurable Young's Modulus quality to it... There may be some seemingly stupid hacks one could pull off, provided it's possible to control and modify gravity waves. Think along the lines of interference patterns, and then things may get interesting. Alcubierre's work would be somewhat less out of reach in practical terms. Although a bit of a reach since those implications would be more "fun" than only explaining how star stuff works.

John Moffat looks at the camera like he knows something

Ist es dann demnächst eine Mogfinsternis? (Sorry that one only works in German)

I've heard about galaxies who seem to have lost their dark matter after colliding, is that actually a thing and how do any of the modified gravity theories explain such a thing?

@shockingboring_

23 күн бұрын

I guess the whole "lost their dark matter after colliding" thing is just an interpretation of the observations from an extremely large distance. not necessarily a fact.

6:23 I also wonder what Jacob Rees-Mogg has to say about the matter. 😂

If you treat gravity as a literal fabric, when you pull on it with a dense object, it is possible the outer sides of it actually stretch, and could be anti gravitational.

@altrag

26 күн бұрын

"Stretching" is exactly what happens (at least according to general relativity). That stretching _is_ gravity. Anti-gravity would be spacetime "bunching up", and as far as we know that doesn't happen in the real universe (though its not technically forbidden by GR, and those "warp drive" designs you see mentioned occasionally - including on this channel - attempt to utilize that feature. Of course they also require things like negative-mass matter which as far as we know doesn't exist so that's not helpful in the real world no matter how interesting the math behind it is).

@MatthewSuffidy

26 күн бұрын

@@altrag Not to offend anyone, but maybe it is possible Einstein did not model the fabric quite the way it functions. Like he made an assumptions things would always take the shortest path. Thanks though

@altrag

26 күн бұрын

@@MatthewSuffidy > maybe it is possible Einstein did not model the fabric quite the way it functions Not only is that possible, its almost a certainty. General relativity does not work with quantum mechanics, so we know they're bot not "quite the way it functions". That is not the same as being wrong though. Whatever replaces GR will necessarily be a "better" version GR in the same way that GR itself is a "better" version of Newton's F=ma. That must be the case because GR matches observations very, very well and the new theory also much match those same observations in addition to explaining new things that GR can't. If there is any sort of anti-gravitational "bunching up" or however you want to visualize it, it would necessarily be at an incredibly tiny scale for the simple reason that we would have seen it if it was at a scale we could see using current theories and equipment. The biggest hurdle we have to coming up with a better theory - whatever form that theory takes - is that neither GR nor the SM are expected to break down until we reach energy levels a million or more times higher than what the LHC can produce. To give you a sense of comparison, the new FCC collider that scientists currently want to build would be around 7 times higher than the LHC's energy levels. That is a very, very long way from the factor of a million we really need. I've seen estimates that a collider large enough to hit those energies would have to be somewhere in the ballpark of the Earth's orbit around the sun. Just a tad beyond our current engineering capabilities. That leaves us with astronomical observations and just crossing our fingers that we're looking in the right spot in the sky with the right telescopes when something happens that breaks our theories in a way that a new GR solution can't fix. It's part of why black hole physics has been such a big deal over the past couple of decades - they're one of the few objects in the entire known universe we have any hope of studying that can potentially do something extreme enough to make us reevaluate our current ideas. > Like he made an assumptions things would always take the shortest path That's not really an assumption. Or at least not Einstein's assumption. Its actually the principle of least action which predates Einstein by a couple hundred years. All Einstein did was reformulate it. In his theory the "least action" is achieved by following the shortest path through an appropriately curved spacetime. But the "least action" requirement itself comes from elsewhere. At the end of the day though, none of that matters. What matters is whether or not it matches observations and so far, GR passes that test with flying colors (mostly - adding an entirely unobserved mass is kind of a hack until and unless we actually find a dark matter particle - that's why a lot of scientists don't like the idea and are trying to find alternatives to GR). If you want to have a useful theory, you need to start with matching existing observations. If you want to posit a form of anti-gravity, you have to explain why we haven't seen such a thing yet - in addition to your normal-gravity side of the theory matching the stuff we have seen. Because if your theory doesn't match existing observations, then its immediately wrong - not just the "we know its only an approximation" kind of wrong that GR is, but flat out 100% incorrect. And unfortunately that almost always means doing the math. Nobody's going to take a 3-sentence "what if" seriously. Even if you're somehow right in some way, nobody will pay attention if you haven't done the work to prove that your idea at the very least works as well as GR or any other idea, nor is anyone else likely to bother trying to do the math for you.

So when do we get MEG (Modified Einsteinian Gravity)?

@Nomen_Latinum

26 күн бұрын

That's exactly what this is!

@seriousmaran9414

26 күн бұрын

​@@Nomen_Latinummine is more accurate 😜 Then MOG sounds like a cat.

@Nomen_Latinum

26 күн бұрын

@@seriousmaran9414 I suppose, but when theoretical physicists talk about "gravity" they are almost always referring to General Relativity unless otherwise specified.

All I'm sure about it's that it can be either a pain or a blessing going up or down - depending. Would be nice to figure out how to control it.

Thanks so much for creating and sharing this informative video. Great job. Keep it up.

I have a feeling Sabine doesn't know what it means "to mog", and her grinning like that in the thumbnail next to giant yellow text spelling out "MOG" is exactly my speed. I want that on a shirt.

@TooSlowTube

26 күн бұрын

I don't know what that means either. So far, I've got "to move away : depart-usually used with off or on." and "Myelin Oligodendrocyte Glycoprotein (MOG) is a glycoprotein which is part of normal myelin and is found on the surface of the myelin sheath of nerve cells".

@Asdayasman

26 күн бұрын

@@TooSlowTube It originates in the incel community. When the "Alpha Male Of the Group", the AMOG does something, it mogs those around him. Mogging someone else is the act of doing something supposedly better than someone else. When the guy at the gym heightmogs you by being taller, you can liftmog him by lifting heavier weights. To an incel, every social interaction, however slight, can be seen as a series of back and forth moggings. Sabine knowledgemogs us every time she uploads a video.

@mikeoxmall69420

21 күн бұрын

She's even mewing in the thumbnail 💀

Doesn't the introduction of new (quantum ?) fields introduce new particles as well? Do those predicted particles have a mass that would show up in the LHC? Also I'm curious about what you think of Neil Turok's hypothesis that dark matter is (massive) right-handed neutrinos - one of the three predicted ones in particular. I don't recall that subject being discussed in any of your videos.

@SabineHossenfelder

27 күн бұрын

In modified gravity, the fields are normally assumed to be classical, ie they don't come with particles. It's because they're assumed to be part of the geometry, and if they had quanta that would be a sort of quantum gravity. One can ask whether it makes sense to assume they're classical, and I have wondered about that, too, but that's how the theory currently works. As to Turok -- there are so many particles that dark matter could be made of, I could talk about a different one each day and after a year I'd still be talking... Yes, right-handed neutrinos are good in the sense that we can need them for other things, too.

@yeroca

27 күн бұрын

@@SabineHossenfelder I think part of his argument is that no more particles need to be "invented" for dark matter to be explained, if that one right-handed neutrino has the properties they hypothesize. Wouldn't other possible dark matter particles be outside of the current Standard Model? I think the assumption is that the right-handed neutrinos are implicitly inside the Standard Model, even though no accelerator has observed them. I didn't really follow his explanation about why the abundance of them would be so large; it was over my head.

@Thomas-gk42

27 күн бұрын

It´s predicited that they have a huge mass, so they perhaps don´t need to be that common, to explain DM. But are they part of the standard model? Just like susy particles, that were invented to make the standard model more beauty, but also never were found?

@yeroca

26 күн бұрын

@@Thomas-gk42 True, but the idea of having observed "handed" particles with no observed opposite-handed particles is disturbing and hints at what probably exists, even if they haven't been observed yet. Much like antimatter at the beginning of the 20th century.

@Thomas-gk42

26 күн бұрын

That´s fairly true.

as a layman, I appreciate that someone seems to at least be coming close to a formula that can describe what we see with accuracy, even if the underlying truths are somehow different, being able to accurately describe it at least may give us a way to find methods to test what "it" actually is more fundamentally.

Where I live, we have almost as many white non-binaries as coloured binaries

Does the expansion of the universe cause gravitational waves to stretch in the same way that it causes light to stretch?

@maritaschweizer1117

26 күн бұрын

I guess you mean stretching the wavelength. The Doppler effect applies to all waves it means also to Gravitationlal waves. The interpretation of rhe LIGO data need the Doppler effect to be implied.

@choilive

26 күн бұрын

Yes, the stretching of electromagnetic waves due to cosmological expansion would apply to gravitational waves as well.

First...second time.somehow your video release is exactly coinciding with my break time.

@Thomas-gk42

28 күн бұрын

entanglement!

The 5th element or ahem dimension Dr. John Brandenburg style works for my field vehicle designs but Plasma Cosmology makes sense.

Two genuine questions: 1) isn't the moffat gravity the scalar-tensor-vector gravity? If thus, doesn't it predict a field that would slow down the speed of gravitational waves? Have they reconcile their theory with the fact that they travel at c or do they claim measures are inaccurate? 2) can that "counter gravity field" somehow be related to dark energy?

I guess you could say that MOND got MOGged... This has to be the cringiest comment I have ever made.

It's over for us. This is a different MOG.

@alucardhellsing7435

24 күн бұрын

Never began

These segments are the best stuff on KZread.

noo way, even physics mogged me 💀

Sabine, you are one of the few people in the public eye I would actually regard as an educator, rather than just a communicator.

I just read the Science article about strong magnets changing the magnetic field of meteorites. Does this mean a strongly magnetic asteroid meteor could change the magnetic field and/or gravity of Earth?

@SabineHossenfelder

27 күн бұрын

A large enough asteroid can do pretty much everything, including killing all of us. So I think the answer is "yes"

@JanicePhillips

26 күн бұрын

The Universe is Electric.

@user-jr4uf1dc9k

26 күн бұрын

​@@SabineHossenfelderbarry I can feel the magnitic forces here. 😂😂😂🌠🌠🌠

@user-jr4uf1dc9k

26 күн бұрын

​@SabineHossenfelder barry reformat I know, the nature of your game.🤠

So many questions.. 1) if DM is non-interactive with normal matter except gravitationally, shouldn't it, no matter how sparse , still be accumulating in the centre of every object with a gravity field? And how long would it take for enough DM to accumulate inside a star to throw off the explosion/compression balance of gravity vs fusion? 2) I've always been confused about where DM is supposed to be, if it's outside galaxies then how does it increase galactic escape velocity enough to keep fast moving stars in? 3) is it that galaxies' rotation curves have a lower derivative than expected or that it has a zero derivative with distance from the core? 4) if MOG has a distance step change, could we use relativistic effects to find somewhere in the universe a jet of matter is moving fast enough to contract space and so cross the mog threshold and look there for some sort of discontinuation?

@Vastin

26 күн бұрын

RE: #1, if I'm not mistaken, DM isn't supposed to clump like regular matter because it is non-interactive (even with itself), so it does not experience any kind of friction - so it just endlessly falls through stars (and the galaxy itself) without ever locally accumulating. However, it SHOULD accumulate when it encounters black holes as it should not be immune to interaction with an event horizon, so it should hypothetically affect the growth rate of supermassive black holes in particular.

@richarddavis2605

26 күн бұрын

@@Vastin "it endlessly falls through stars and even galaxies", what is it falling towards? It is gravitationally interactive, and it exists inside a galaxy, so there is no reason it wouldn't end up in the middle of stars (and planets and if it's small enough protons). Maybe that's why nobody can find it, it's all sitting in the bottom of various subatomic gravity wells 😂

@Vastin

26 күн бұрын

@@richarddavis2605 So, think about if you had a rock sitting still at the 'edge' of our solar system, then let it fall towards the sun. It will accelerate the whole way and by the time it reaches the sun it is going extremely fast. Now imagine that rock passes through the sun as if it were not there at all - it will now fall all the way through the solar system to the far edge before gravity can stop it again and pull it back - and it will do that over and over for eternity, yoyo-ing back and forth through the whole solar system. It will never come to rest in the sun, because no friction will ever slow it down. This is what dark matter would do in a galaxy - just falling from its edges through the center back out to the edges, and because it is moving much more slowly at the edges than it is when moving through the center, it will spend most of its time there, forming a denser halo with a relatively EMPTY center.

Among all of those theories, I really like Quantised Inertia (QI) Theory. It explains everything without fine tuned parameters, it explains wide binaries, universe expansion, the source of the G constant, and explains multiple anomalies. It is consistent with the information theory, relativity and doesn't need ad hoc phantom mass distributions, or dark energies.

Oh no, we just buried MOND, but its offspring appeared at the funeral. Need to dig another grave nearby for the time when "MOG" dies.

Is this correct? A vector is a mathematical entity that has both a magnitude and a direction, while a scalar is a quantity that has only a magnitude. In other words, a scalar is a single number that describes a quantity, while a vector is a directed quantity that is represented by an arrow with a specific length and direction.The length of a vector is its magnitude, which is a positive scalar. The direction of a vector is given by the angle it makes with a reference direction, often an angle with the horizontal. The direction angle of a vector is a scalar.When a vector is multiplied by a scalar, the result is another vector of a different length than the length of the original vector. Multiplication by a positive scalar does not change the original direction; only the magnitude is affected. Multiplication by a negative scalar reverses the original direction.Two or more vectors can be added to form another vector. The vector sum is called the resultant vector. Vector addition is commutative and associative.In summary, vectors have scalar qualities such as magnitude and direction angle, but they are not the same as scalars. Scalars are single numbers that describe a quantity, while vectors are directed quantities that are represented by arrows with a specific length and direction.

@SabineHossenfelder

27 күн бұрын

Yes, that's correct.

@ImogeneRichards

24 күн бұрын

​@@SabineHossenfelder Sabine what happens if a complex vector is multiplied by a complex numbered scalar,does this situation show up at all in any interesting physical way? Sorry to pester you Thank you for being so honest,and self critical,its really refreshing

Hi Sabine. Great channel. As we are still exploring alternative gravity theories, I’d like to have your thoughts about Entangled Relativity theory from Olivier Minazzoli and al.

Brilliant video! I suggest reading López, Á.G. On an electrodynamic origin of quantum fluctuations. Nonlinear Dyn 102, 621-634 (2020). This work uses pure electromagnetic mass to show that Newton's second law comes from electrodynamics (basically inertia is a force of self-induction coming from Faraday's law) in the ordinary scale limit. However, there are many other contributions to inertia due to retardarions in the self-force coming from Lienard-Wiechert potentials. It concludes that Newton's mass, inertia and, consequently, the force of gravity, are non-fundamental, but emergent electromagntic forces. It is really challenging to derive Milgrom's law and the law of gravitation from classical electrodynamics. Failed so far...

MOG? So the "missing mass" problem is caused by the Moogles.... Interesting.

I often watch videos by a very wise physicist who criticizes theories which cannot be falsified because they keep getting modified to accomodate data. I think this is such a case. And the name of this physicist is... Sabine Hossenfelder

@yeroca

27 күн бұрын

It is falsifiable, but so far it fits the existing data. But that doesn't mean it's the best answer either, just as "epicycles" fit the planetary movement observations centuries ago. Epicycles fit well, but didn't really represent the real nature of the mechanics. It might be one of the tools to help us make better predictions until we have a better theory for the underlying reason why it seems to behave like MOG.

@arctic_haze

27 күн бұрын

@@yeroca Well, MOND seems dead so now we have another modified gravity version. This is simikar to the way the Steady State Universe was dying.

@SabineHossenfelder

27 күн бұрын

MOG is not a modification of MOND. They're two entirely different theories. MOND doesn't have any additional fields. The two actually have very little in common (besides the similar sounding name).

@arctic_haze

27 күн бұрын

@SabineHossenfelder Steady State versions were also very different but all had the same aim: to debunk Big Bang. It's the same story with modified gravity versions. Their sole purpose is to debunk dark matter, and they are becoming more and more complicated. The typical traits of a dying paradigm.

@Thomas-gk42

27 күн бұрын

@@arctic_haze Steady State versions were kinda standard model BEFORE BigBang was, no? It changed with the discovery of CMB.

Modification with distance? Like electron shells? I don't know John Moffat or his theories, but I always thought that made more sense to me than any alternative.

Wide binaries are still gravitationally coupled, so wouldn't they still be too close for the effect to be seen?

A recent article in Scientific American claims updates findings on the strong force at greater distances. I am hoping a video about that is on its way, but I also wonder if something like the newer QCD model could be a candidate for the rotational speeds of galaxies, perhaps in a way that perturbs spacetime into having a pressurelike differential that equilibrates to what we see.

@SabineHossenfelder

27 күн бұрын

I saw that but couldn't find much to say about it. I'll have another look. The QCD potential has the wrong asymptotic behavior to work for rotation curves.

@tomholroyd7519

26 күн бұрын

@@SabineHossenfelder Somehow I think that just saying the "strong force" at "galactic scales" might actually cause a linguistic singularity that collapses the internet.

@user-jr4uf1dc9k

24 күн бұрын

​@@SabineHossenfelderbarry when are we coming home.

@user-jr4uf1dc9k

24 күн бұрын

​@SabineHossenfelder barry. Just stop your crying. It's a sign of the times.. welcome to the final show. Hope you're wearing your best clothes. You can't bribe the door on your way to the sky. You look pretty good down here, but you aren't really good. We never learn. We've 🤠been here before. Why are we always stuck and running from the bullets.?. THE BULLETS.?. We never learn, we been here before, Why are we always struck and running from the Bullets.? Cool song barry. 🎵

I saw that! You're coercing Albert's opinion. I saw you hit Albert. 😅

I never understood why would one modify the Newtonian model if that is clearly incorrect. Dr. Moffat is on to something.

Yup, it's quite troublesome things dont get any attention, just because the maths is a bit more complicated. Similar with spacetime torsion.. if space time bends, for me of course it can also twist. Changes quite a few things for insides black holes (no singularities), but no torsion vectors are not nice a math. Unfortunally we still cant measure it tough.

Gravity just works differently at different scales. No dark matter.

The reason astrophysicists believe in DM is because there is a robust corpus of evidence for it.

Distance, I think, is on the right track, but for the wrong reason. I believe there are around three related factors at play: 1) I'm convinced that the causation of movement segregating gravitational pull from push increases the deviation with distance. That is dark matter (pull) and dark energy (push). Gravitational pull experiences its least skewed effect at close range and is amplified only slightly at far range due to the movement caused by the push at large range. The more objects are pushed, the greater their gravity at large distances. 2) Both gravities, however, are exacerbated by all the photons moving about which are also losing energy due to the interactions with gravitational objects, both pushing and pulling, giving us a quickly accelerating universe. (It is all an interplay.) 3) This in turn creates a mirage distortion, telling us objects are further (rather than closer) than they really are. (This also explains why we think we should be seeing much slower rotations in galaxies than we are. We are seeing their actual rotation speeds, but our faulty measurements due to slowed light tell us that they should be slower. So it is a little of each. This means that technically, we do not need a theory of modified gravity, but an extra figure that accounts for the additional divide between push and pull that is caused by the push's interaction with gravitational bodies the further out you go. Gravitational pull is one steady figure that we know well, and the other figure is dependent upon the masses of galaxies and their larger parent structures. A third figure must also be considered, namely the effective mass of all the photons moving about. (They're not stationary, so they're not entirely massless. We know this.) But this figure is smaller than we would calculate based on observations since our observations are being skewed. The calculation for these effects would best be calculated as a coil of string. The further out light travels, the more coils you can fit into that distance. So you count, not the length of the coiled wire, but counting the number of coils that fit within that distance without measuring the width. This represents how much energy is being displaced the further back in time you go.

Any modified gravity theory should be able to explain neatly the gravitational lensing of the bullet cluster the same way as relativity does.

Everyone knows it's just trillions of baby black holes sprinkled throughout the universe like powdered sugar on a donut.

@TheShootist

26 күн бұрын

so where are all the gravitational lensing events one would expect to see?

@ticthak

25 күн бұрын

​@@TheShootistWidely separated microscopic black holes would be indistinguishable from dust in their spectral effects.

I stopped believing omnipresent invisible things that shapes the universe long time ago.

@schitlipz

26 күн бұрын

I'm the opposite.

getting mogged by sabine was the last thing i ever expected to happen but here we're... lmaooo

As a casual physics nerd the dark matter problem sounds to me like the concept of the "ether" which was prevalent in the 19th century as an explanation for light's properties. Idk, just a thought