Is Acceleration Relative??? Dialect is WRONG!!!

[@dialectphilosophy]

Hey there! Someone pointed us to this video recently and we really enjoyed it! First off, we think it’s very important to have and maintain open dialogues about topics like these and think it’s great that you have brought forth concerns and criticisms. As for our response, we’d stress two main things. First, we’re hardly the first people to argue against the definability of absolute motion: Einstein argued against it not only in that 1914 paper but also in a 1918 paper as well, stating there that it made no sense to the consistently thinking individual. Then of course others such as Herman Weyl, Mach, Leipzig, etc. all argued the same thing. As to defining interial frames via conservation of momentum, this unfortunately suffers from the same circularity of definition. How is it you could possibly measure the true mass of the object without first invoking an inertial frame? Or likewise, how could you possibly measure the true velocity of an object without first invoking an inertial frame? As for rotating your spring, this implies you have already constructed a frame by which you have laid out a notion of euclidean space complete with Euclidean angles. Where and how and with what did you do this? You could only have constructed such a notion of space with instrumentation that could itself ever have changed when rotated, but there’s no way of knowing whether your instrumentation changed when rotated unless you have some further layer of instrumentation of which you are certain does not change when rotated. This of course leads to the absurdity of infinite regress of instrumentation. Indeed, when you think it through carefully, you will see that no apparatus despite how cleverly conceived will ever overcome this issue - because at the end of the day, it’s about epistemological uncertainty. It’s a philosophical realization that’s unfortunately difficult for the more practical-minded physicist to grasp, or if, when they do, a realization they tend to dismiss as pedantic. But ultimately we’re going to see such considerations become utterly crucial when we seek to realize the physical meaning of theories like relativity. So we hope you’ll stay tuned to our channel. Great job again and keep up the good work!

[@lukasrafajpps]

HI! I am glad you somehow found a way to this video and thanks for the reply. I don't even know which issue tackle first. Could you please post the link for the 1918 paper? The mass thing is a fair point although I don't think we need to measure the masses at all. If something isn't traveling with the speed of light, then there is something stopping it and we call it mass and there sure is a certain number for each object even though you can't measure it. If a massive object suddenly change direction or relative velocity without any cause, then it is safe to say the momentum isn't conserved (there are no any other particles comming out from the star to conserve the total momentum). You can say a tricky argument that the particles that are comming out of your rocket engine are carrying the momentum and since we don't know their masses we can't know their momentum but that would be 1) non-local therefore action-reaction problem and 2) if you think about it, the particles would traveled in the same direction as the acceleration of the star, therefore if we don't allow for negative mass, the problem can't be solved even in non-local scenario. The spring: Again, fair point but if the space was somehow curved, then the spring length would change due to the curvature by certain amount and due to force by different amount than the measuring instrument. why you think we can't measure velocity without inertial frame? or mass? In special relativity, every observer has its own distance measuring aparatus and a clock that are all identical. velocity is just simply a small change in the position divided by the small change in time so all observers are equiped to measure it and you cal also do it under acceleration. From your videos I see that you like the idea of aether is that correct? Thanks again for the reply to this video and looking forward for your future videos about this topic :)

[@harleyquinn8202]

Suppose I am in a closed container floating in space. If I suspend a ball in the air and let it go, I can measure its acceleration relative to the container. If there is no relative acceleration then I can safely assume that my container is in an inertial frame. The problem with this argument is frame dragging by nearby cosmic objects: the galaxy, our super-cluster of galaxies, visible universe, etc. Our visible part of universe might be accelerating rapidly or rotating relative to the whole universe and we can not feel or detect it.

[@AntiGroup]

​​@@lukasrafajppsHey there, I have gone through your videos and comments and I see All your points are okay but the argument you are having has become circular now because you in the process have your way. I have been also working on such problems for years hence I am interested as well where this leads to. In actuality from where I see it, Dialect's emphasis is about the relativity of motion, all motion which includes acceleration as well, because as stated by Einstein himself, Absolute motion makes less sense as well as it goes against the idea of relativity. Yes SR postulated about relativity of inertial frames but it was incomplete as well and Einstein in his later life tried attempting extending SR in such a way that it includes acceleration as well, beyond General relativity. And about the idea of aether, I feel the journey to knowing the relativity of all motion goes through this idea that's why dialect's emphasis is upon it the way I see it. I hope if this helps a bit. . I too am working on it and I'm hoping if I get some insights by your discussions ahead. Really excited!

[@lukasrafajpps]

​@@AntiGroup Hi, If you say it is circular you it would be nice to give some example otherwise there is no way I can respond. But I get it. there is an infinite room of asking the "why" question and unless we don't have the theory of everything there will always be questions to ask.

[@TheOneMaddin]

Usually I am with you. But I don't get this: if there is a frame in which I can turn a spring by 180degree and measure no change in length, this is strong evidence that this frame is special, No?

[@jessstuart7495]

Dealing with accelerating (non-inertial) reference frames was the primary motivation for Einstein's General Theory of Relativity (1915).

[@maximusideal]

I love your concise and precise summary of Dialect's points.

[@everythingisalllies2141]

I love that he thinks he understands that which he does not. If he actually understood, he would know that SR theory is nonsense.

[@mayatrash]

I'm a physicist and I must say, I think dialect is still correct, even though is arguments are novel and not perfect. Mach was right. Everything is defined relative to other things. There is no calibration of anything without a zero point. There is even no symmetry if there is no equilibrium. This holds for anything. If this would be solvable the ground state problem in quantum field theory would not be a millenium problem - I suppose it's not solvable. Every respectable physicists knows that we never have any way of measuring energy, just energy differences. And the same argument can be made for anything.

[@dericksmith740]

finally we reach the limit of human cognition and know the world may be more than human brain can handle

[@marcossidoruk8033]

The "ground state problem" as you call it is a purely mathematical problem that has NOTHING to do with our ability (or lack thereof) of measuring energy, it just asks you to show wether or not a constructive QFT axiomatic system exists such that an arbitrary Yang mills theory has a finite mass gap. All of these things are mathematically perfectly well defined. Besides, the mass gap has nothing to do with vaccum states to start with, the mass gap is just the difference in energy between the vaccum and the 1 particle state, it is best though of as the mass of a particle given by a field.

[@SpacetimeTraveler-p4e]

You're not a physicist. Acceleration, i.e. physical acceleration is any motion relative to the local gravitational field. A physicist would know this.

[@marcossidoruk8033]

@@SpacetimeTraveler-p4e Depends how you define the gravitational field and what do you mean by "relative to the local gravitational field". Acceleration is more precisely defined through the directional (along the direction of motion) covariant derivative of the 4-velocity.

[@SpacetimeTraveler-p4e]

@@marcossidoruk8033 The standard definition of a gravitational field is an equivalence class of spacetimes, i.e. solutions to the gravitational field equations. The local gravitational field is defined by its geodesic structure (the set of all geodesics) and motion relative to the local gravitational field is any curve that does not satisfy the geodesic equation. This amounts to what you wrote concerning the proper acceleration.

[@ipaulino84]

Valeu!

[@lukasrafajpps]

thanks😍

[@marsglorious]

This guy was lucky to have a critic as kind and illuminating as you.

[@lukasrafajpps]

thanks for the kind words :)

[@Andrew0you0tube]

​@@lukasrafajppssubbed without hesitation, thanks for explanation)

[@HaveANceDay]

I think it is a just refutation, because he hás many good points. He may be wrong in many points, but the questions he raises are worth thinking.

[@mehmetsahin9276]

May I ask why you are angry? I'm sure even God wouldn't be as bothered by your rules being questioned as you are.

[@notmyname4261]

@@mehmetsahin9276 Imaginary friend alert

[@filker0]

I made a similar argument in the comment section of the Dialect video in question, and got a similar answer. My observation is that even if you can't calibrate the accelerometer in an accelerating frame of reference (which I don't believe is correct), the fact that you are accelerating will be obvious My physics background is old - my father is a theoretical physicist but my last physics course in college was more than 40 years ago.

[@brubrusuryoutube]

one thing l dont understand is how the derivative of something relative (speed) can be absolute. Can anyone explain?

[@GerardDubois-yn3kt]

If you add any constant to a function (to make it relative to something else), its time-derivative stays the same. So the value of the constant doesn't matter.

[@brubrusuryoutube]

@ what does the constant represent? relative to what?

[@SpacetimeTraveler-p4e]

It isn't absolute. You're thinking of the coordinate acceleration, -Γ^α_{βγ}u^βu^γ, which is NOT the absolute acceleration, u^α∇_αu^β.

[@brubrusuryoutube]

@@SpacetimeTraveler-p4e my problem with four acceleration is that it tells us that acceleration can be an absolute concept, which is incoherent with is being the derivative of four velocity. I understand that you can derive is from measurements by applying Einsteins math (deviation from geodesics using covariant derivatives). But the issue is that it is never directly experienced or measured. Hence its ontological existence requires more proof than just it has to be a thing because Einstein is right. Absolute acceleration is not valid outside of Einstein's frameworkl What I'm saying is that 4 acceleration might not even exist, since it directly depends on the metaphysical assumptions of Einsteins math being right. Which we have reasons to doubt.

[@SpacetimeTraveler-p4e]

@@brubrusuryoutube The absolute acceleration is the experienced acceleration, the acceleration measured by an accelerometer and produced by electromagnetic interactions.

[@AnyVideo999]

I think Ive finally been able to clarify this discrepancy. A big realization of GR was that _intertial_ mass and _gravitational_ mass are exactly the same thing. Forever, Newtonian physics took this fact for granted and it would take a much deeper theory to realize the two could be different but aren't for a natural reason. Getting back to this question, there are indeed two notions at play: acceleration and "proper" acceleration. For example, a simple case in SR demonstrates that viewing an object with constant proper acceleration from your own rest frame results in diminishing acceleration. Consider likewise using polar coordinates to describe motion and sure enough what we believed to be acceleration in our coordinates experiences no proper acceleration. What is now the underlying connection is that using light to define your coordinate spaces (and also the connection between local tangent spaces in GR) now gives you a definition of acceleration which coincides with proper acceleration. Since we've evolved to understand our world on this manner (space is Euclidean by equal time travel in all directions by light-ray) we overlook this coincidence. Just remember, if you have a manifold, the choices of coordinate maps and metric is always up to the mathematician/physicist. Local tangent spaces on curved space are unrelated to eachother naturally and it is through observation we may conjecture a natural metric for spave time. And only once you have a metric can you begin to define invariants which everyone can agree upon such as whether or not a path is a geodesic.

[@RangQuid]

I think the conservation of linear momentum is not enough to define an inertia frame, you also need the conservation of angular momentum. Because a ball rotates on a fixed axis has zero momentum but a non-zero angular momentum. But this definition intrinsically assumes that spacetime itself is uniform and isotropic.

[@cermet592]

Many parts of a ball absolutely do experience acceleration effects and hence have momentum. As for elementary particles (zero diameter) that is another issue but likely these 'particles' do not 'spin' as we use the term for finite objects.

[@RangQuid]

@@cermet592 Please note that the linear momentum is a vector so despite that the momenta on different parts of the ball are non-zero, the total momentum of the ball is zero provided that its center of mass is kept fixed.

[@Al-cynic]

I know your talking about relativity and acceleration. It's just that it made me think of Subir Sarkar and his argument against isotropy and homogeneity regarding our frame of reference, in reference to the validity of the Dark energy postulate. Any thoughts on that?

[@onemediuminmotion]

Beautiful! Thanks for your excellent articulation.

[@christianlibertarian5488]

I have watched that exact Dialeckt video. It definitely seemed off on the acceleration issue, but I couldn't figure out why. Thanks for clearing it up for me.

[@WoodlandT]

I tried watching it yesterday and made it about 2/3 through. It wasn’t making sense to me but I also didn’t know why

[@barakenat]

Perfect video! Dialect almost confused me but then I realized exactly what you explain. I wouldn't need 4 springs. Just rotate the string and see if its length is changing. In the twin paradox, even if the outgoing twin was moving in constant acceleration and at zero time turns back in constant deacceleration, a string in his direction of motion would at that single point change its length while on the earth that same string will stay the same length all the time.

[@lukasrafajpps]

exactly!

[@TheLoveajay]

But the paradox still remains intact! First of all each observer is at origin in their frame of reference. So both would think that the other one is moving and in order to meet, the other one should accelerate. So the meeting is virtually impossible. Even if one of the observers decides to accelerate still according to his point of view the other one accelerated,since he's still at the origin in his frame of reference. So both would never agree who accelerated. And if we conduct a black box experiment. Place both observers in black boxes and set the relative speed close to speed of light and set them apart for let's say 10 years for 1st observer. The other observer would think only 8 years (assuming) elapsed, but the 1st observer would still think that both aged 10 years because according to him both met after 10 years . And similarly the second observer think both aged 8 years. Now don't say that proper acceleration is absolute because Einstein's whole theory is based on coordinative observations. If we apply common sense then whole theory would collapse. Example: Einstein says two observers would never agree on the moment of an event happening because their clock can never be synchronised; but if we take speed of light in consideration and distance between both observers then we can synchronise both clocks. But Einstein emphasized on physical observation through eyes, that where it is impossible.

[@caveman36]

The observer in earth also sees that his spring shows an acceleration in the down direction. Assume the space going twin travels at 9.8m/s^2 in a curved path such that he returns to earth eventually. The quantity of thrust remains the same but the direction changes. So now both twins accelerate the same amount, but one experiences a change in direction. How does this affect the paradox. Which twin is older and why?

[@pwinsider007]

​​@@lukasrafajppsAcceleration should be theoretically defined first and not with the help of any equipment firs ,if it can't be defined theoretically then its definetion with the help of any equipment is wrong.first define theoretically then define with the help any equipment or machine beacuse physics is independent of any equipment just like your ball with springs.

[@lukasrafajpps]

@@pwinsider007 Theoretically it is relative quantity. This symmetry is broken in physics because the world we are living in has certain additional rules but the symmetry of relative velocity remains. Again I need to mention, in general relativity, there are two types of acceleration from which one is relative.

[@victormd1100]

I still honestly dont understand one thing: Figuring out if momentum is conserved is the same as finding the center of mass of the whole universe and seeing if it moves in uniform motion. However, supposing for a moment the center of the universe is exactly one meter above you and you begin to spin around it's axis you'll see that it is still fixed (thus momentum is conserved) but now everything is spinning around you ( and thus, are being accelerated toward you ). How can you know if it is you who is rotating or if the things are truly rotating through an axis through their center of mass?

[@lucassiccardi8764]

Very good point.

[@SpacetimeTraveler-p4e]

The physically rotating object has a proper acceleration, which is any motion relative to the local gravitational field.

[@APaleDot]

Excellent explanation. As someone trying to learn about relativity, this dialogue is really patching up some weak spots in my understanding!

[@philoso377]

If you have experience calibrating a tilt meter on so call horizontal surface but not knowing it is true or not, you know what I mean when it comes to accelerometer calibration. We orientate the accelerometer under calibration in all theta and phi angles and record all data-angle data points then take a vector sum (average) to a calibrated reference.

[@asyncasync]

Gravitational pull is almost uniform, but you still have gravitational tidal forces that can tell you the direction.

[@iliaadamanthark8336]

Ok, so tell me, if some planet just cross our planet at 99% the speed of the light. Will the person on that planet be the younger one (experience slower time), or it is us that is younger? Which planet accelerate according to absolute acceleration?

[@mathepunk]

This reminds me of Mach's Principle concerning absolute rotation.

[@philoso377]

Calibration ? If we are uncertain about static inertial calibration how about dynamic inertial calibration? Set the spring+mass in linear oscillation.

[@EugenethePhilostopher]

04:17 No, the isotropy of space means that the angular momentum is conserved. The conservation of momentum is connected to homogeneity of space.

[@juleskurianmathew1989]

When an accelerometer is kept on ground, there is a downward deflection. This is due to gravity. So the calibration here is already made! Now if that accelerometer starts to accelerate horizontally, there will be horizontal deflection. Both these deflections correspond to relative acceleration; not absolute acceleration. Earth is in acceleration wrt local universe. When accelerometer was at rest wrt ground, it is still in acceleration wrt local universe! And what should the deflection on accelerometer, which is difference of accelerations of accelerometer and earth correspond to? Its relative acceleration! I think dialect is correct.

[@5ty717]

Communication is a function or thought. Your thought processes are deeply intuitive. Excellent communicator.

[@rentlastname2824]

So you're saying that because the mass of the Sun is so great, it is unlikely to be accelerating towards you, therefore it is your ship that is accelerating? And this gives the reason to break the symmetry of the twins paradox?

[@lukasrafajpps]

no unlikely but impossible.

[@KamikazethecatII]

@@lukasrafajppswhy is it impossible?

[@nickmerix2900]

How can acceleration be absolute and velocity relative ? Isnt acceleration just a change in velocity ?

[@bazzaar1869]

The number of times otherwise inteligent people forget the simple expedient of changing the orient tation of a measurement device to check for an unexpected offset. Dialect looks kind of silly ploughing on after this clanger.

[@CrucialFlowResearch]

​@silverrahul it's silly from the perspective of science to continue misleading people intentionally when you are aware of a mistake

[@flexico64]

"Acceleration has a direction" man I feel like I said that 100 times during that video! XD Perfect explanation with the 4-spring accelerometer~

[@steveseamans9048]

Excellent explanation of acceleration. So many confused by forgetting it’s an absolute with so much relatively going on. 😊

[@pauloemanueldeoliveirafrei654]

The real question.... " C " in Relativity means linear speed ir angular speed ?

[@kylelochlann5053]

The "c" is the velocity along any time-like curve (the norm of the vector tangent to the world-line).

[@ibrahimghanem5213]

4:34 ;;;; Great video! I had wondered about those things and your video cleared things up for me. However, at this time stamp i was not satisfied with your explanation. Through experiments scientists have proven that Relativity applies to all objects, even subatomic, unthinking objects. We also know that Relativity is local. Given these two "facts" (quotations because what we know to be fact may change with future research concerning ultra-large distances and quantum particles), could one create an intuitive way to test theories of acceleration that only require local reference frames and don't require reasoning on part of the object accelerating /standing still? How could a mere particle deduce that it is more likely for itself to be accelerating than a nearby star? And given there was no nearby star, how would one even begin to model such a situation without referring to distant, non local stars? I would also like to see a video on different, more niche theories of acceleration.

[@SolidSiren]

Dialect doesn't seem to understand what "relativity" means. The "defects" he pointed out are exactly the POINT.There IS no preferred absolute reference frame.

[@nadirceliloglu397]

Can not agree more

[@DrJamTastic]

Acceleration is defined by an unobservable geometry. Gravity is the force (not pseudoforce) that leads objects to move away from geodesic paths (as defined by an arbitrary geometry). The fact that we can choose a geometry in which this force disappears is the strong equivalence principle. We say "gravity is just geometry" but it is rather that it is relative; gravity can't be distinguished from geometry. This is why we refer to the current form of GR as a "geometric *model* of gravity.

[@SpacetimeTraveler-p4e]

We measure that gravity is not a force. It's not a philosophical point for debate.

[@paulg444]

Dialect and this fellow are a gift that keeps giving !

[@nadirceliloglu397]

Dialect is providing wrong arguments with many flaws.

[@DOWNLOADZ]

It seems to me that everything is moving through space and therefore there can be no frame of reference that is NOT moving.

[@lukasrafajpps]

Well, that is true but the point is that there is no physical difference between a moving frame and a astationary frame so any inertial frame can be cosidered as being stationary and other are moving. That is what the principle of relativity teaches us.

[@alejosanchez3309]

First, we need a frame-independent definition of force, but we can't have that, so an inertial frame is more of a choice. In an inertial frame, the fundamental interactions (which are also a choice) are the only interactions that can change the momentum of a body. And so, our frames are approximately inertial frames.

[@declanwk1]

Dialect seems to think that relativity should be discussed in terms of whether it is right or wrong, whereas (with reference to the fact that it has passed every experimental test in the last 100 years) the discussion should revolve around whether he understands it or not. When he has difficulty understanding it, he should not jump to the conclusion that there is something wrong with it. At some point in the future the theory of Relativity will be found to fail in some way, but the people who who make this breakthrough will have enormous respect for Einstein's theory just as he had for Newtons theories which he overturned.

[@GodwynDi]

It already has been, just on the quantum scale, and possibly on very large scale as well. Just as it was a refinement of Newton that worked on the easily observable, we are trying to find the extra pieces for why relativity is wrong at some scales.

[@declanwk1]

@@GodwynDi on length scales which have not yet been reached by experiment, but which we can speculate on, relativity and QM predict different answers which is not the same as saying that relativity is wrong. General relativity was not a refinement of Newton, it was a complete overthrow, which left Newtons laws as a low velocity, low gravity limit of GR. Can you point out a published experiment that proved relativity to be wrong, or the Nobel Prize which was awarded as a result?

[@jonathanhockey9943]

I don't think you understand what a true experimental test is. The theory is designed to evade experimental test, its called general covariance. Regardless, we know one of QM or GR has to be wrong, if not both, as GR breaks down on the small scales and no one has been able to make the Grand Unified Field Theory. QFT is still not a coherent theory, one of it's main discoverers, Dirac, was never happy with it, and Penrose and others raise issues with renormalisation as a coherent approach. String theory is completely unfalsifiable and has way too many degrees of freedom, and the appearance of singularities, regardless how they have tried to embrace this, in reality, a singularity is a place where the laws of physics break down. In other words, the theory has holes, because there will always be places in reality it cannot explain. Don't be fooled by the confident rhetoric of popular science books, anyone who looks into the real philosophical debates regarding this knows there is an awful lot we don't know. And certainly there remain philosophical difficulties with Einstein's theory, regarding its "empirical" status or if it is just operationally accurate or if its fully relational or not, or if it requires background independence or not. These debates go on with top theoretical physicists, I don't agree with the idea of returning to the Aether myself, so I am not motivated by that, I think aether is clearly inconsistent with the variable and dynamic manifold of relativity. But we still have a lot to do to give a coherent, clear and precise ontological interpretation of what Einstein's relativity is actually saying about reality, because the block universe approach of seeing it as a static frozen block does not work, and if it is not a static block how do you geometrise a dynamic, variable and malleable entity? And if it is "curved", it is curved relative to what, for there is no container space to provide a neutral standard of straightness. I think all these geometric metaphors mislead people. What we really learn from GR is that space is distorted, not curved.

[@jonathanhockey9943]

Also regarding experimental test, the philosophical theories for determining what an empirical test are, were all designed around Newtonian science, and the idea of an absolute spatial background to provide a neutral setting for an independent empirical test. Without such a neutral background philosophical theories have problems at placing clearly what is empirical and what is conceptual. This has been an ongoing issue for logical positivism, logical atomism, Neo-Kantianism etc which were the philosophical theories supposed to provide the epistemological justification for the science of the day, which was relativity at that time. (See debates between Poincare and Reichenbach and Cassirer and others at this time for instance, and philosophers like Bertrand Russell.) Yet they failed to provide an independent epistemological justification. Something Kant had effectively set in stone in relation to Newtonian science. Without the Kantian approach, which does not work with relativity, as there is no way to apply global synthetic a priori intuitions of space to variable, unfolding, dynamic manifolds that are only locally compact, we are left in an epistemological quandary, with one side affirming dogmatically whatever official "science TM" says and complacently and naively imagining it is water tight, while all other voices are ridiculed and scoffed at...

[@jonathanhockey9943]

Personally, I think the approach to consider to get at the heart of the ontological implications of relativity is process philosophy or a philosophy of becoming. This was the direction Whitehead took, recent theoretical physicists are coming round to this such as Lee Smolin, and in the philosophical discussion regarding the block universe, check out Richard T W Arthur who gives strong arguments against this ontological account and in favor of a philosophy of becoming. Sorting out these ontological implications, though shunned as not important and people were told to shut up and calculate for a generation or two, the fact is that without clarity here, misleading geometric metaphors can slip in and give a lot of people, including supposed physics experts a wrong impression of what the theory is actually saying about reality, so the inevitable tendency is to exaggerate its scope.

[@universalAxis]

Calibration of an accelerometer could also be achieved by rotating the axis of the accelerometer to align each spring with a 90-degree offset, check measurements, and repeat rotation and check until all springs are read. Then, if each of the 4 (or 6, for a 3-dimensional accelerometer) springs reads acceleration (deformation from baseline) in a particular direction, you have detected true acceleration. Additionally, the known acceleration of Earth’s gravity would provide a baseline to equate applied force with deformation of the material, and allow one to calculate the force of the acceleration detected by the instrument, within some bounded range; possibly with a graphed curve illustrating the material’s properties as measured through controlled experimentation.

[@ingramdw1]

Speaking as a lay person trying to understand relativity, both special and general, my head has yet to stop hurting. I thought I had it worked out until I watch some of Dialect's videos, and now I am just confused again. If anyone knows of any sources that explain what is actually correct, or at least states what are unproven hypotheses, that would be great. And by source, I don't mean scientific papers, I mean a source that someone with an undergraduate degree in something other than physics can grok. Thanks.

[@redred4851]

Dialect’s videos are some of the best. Explaining very well what other channels got wrong. I’m still surprised how Dialect misses this one, when the channel explains more difficult issues. A lot of people noticed immediately it was wrong.

[@nadirceliloglu397]

Listen, are you kidding me? You are not a Physicist for sure. Any Physicist would completely disagree with Dialect's nonsense, mickey mouse arguments. They have nothing to do with Physics man! Get a degree in Physics first and then comment. That will take another 10 years. Happy to wait to discuss with you then, not before !

[@gcangur1]

terbiyesizlik yapma adama Nadir, fizikçinin burada ne işi var zaten? Dangalaklık yapma. İlkel milletin okumuş ilkeli olduğunu ispat ettin @@nadirceliloglu397

[@6TDOW66]

@@nadirceliloglu397 Yes, this is exactly how science advance; attack and berate your opponent instead of arguing your case. If you really have a degree in physics, I doubt the competence of anyone with your degree.

[@nadirceliloglu397]

@@6TDOW66 stop the BS and get a degree first in Physics and then talk. You have nothing to say about this subject as you dont understand the arguments! How can I present to you my arguments if you dont know what we are talking about?! Ha? Tell me! Do you know what relativity is? Do you know what spacetime curvature is? Do you know the Einstein field equations? Do you know what Ricci tensor, Riemannian tensor is? Do you know what differential geometry is? Do you Mr. Know it all!??😅 Once you are ready to discuss with me physics, happy to give you my arguments. Understood? So,stop wasting our time and keep silent! Trying to be polite

[@6TDOW66]

@@nadirceliloglu397 Yes, I'm educated enough not to converse like you.

[@Matyanson]

This explanation is so good! Thank you very much!

[@Matyanson]

I would like to elaborate a bit. There are a plenty of videos explaining General relativity for exapmple from "ScienceClic". They explain that gravity is not a force but an effect of curved space time but none explain why it has to be that way! Your example with the acceleration is very intuitive explanation of why special relativity is wrong and why to fix that, Einstein modified special relativity by adding curved spacetime. Now I am very curious if there could be some "intuitive" example or example on the macro scale where General relativity is wrong. Some example of a prediction using General relativity that is wrong in the real world. In what example would quantum mechanics fail to make an accurate prediction? It is said that one theory claims time is relative while the other claims it is absolute. Since we have an evidence of time being relative, should we favour neral relativity over quantum mechanics and try to "fix" the "time is absolute" in the quantum mechanics. Just like how Einstein "modified" special relativity into General relativity. Because from what I have read, scientists are saying General relativity is wrong, gravity needs to have quantum properties.

[@MATT-ll2zf]

Isn't momentum in GR defined by interia tensor?

[@kylelochlann5053]

@@knowledge.inspector There are two notions of acceleration, Γ^k_{ij}u^iu^j, which is the coordinate acceleration, and u^j∇_ju^k, which is the absolute acceleration measured by an accelerometer.

[@kylelochlann5053]

@@knowledge.inspector Disproving relativity is tantamount to disproving the design for a mousetrap, or a recipe for a cheesecake. Sure you build a better mousetrap or come up with a better recipe for cheesecake, so we can always build a theoretical framework for the gravitational field the better constrains the error bars on our measurements. So your relativity replacement theory would have to fit the data better for say, gravitational wave signals, and so on. If there's no absolute acceleration then force doesn't exist either (F=ma). So what you'd need is an interaction-free theory of matter. For example, two cars move at high speed towards each other and end up in a wreck. What you then need to show is some theory of how the wreck happened given your condition that collisions are impossible.

[@m.c.4674]

I agree , but only if momentum conservation decided who is accelerating . Velocity also causes time dilation, so again who do you choose to receive that time dilation. You can also accelerate both twins by the same amount after moving away from each other at constant velocity.

[@lukasrafajpps]

Hi, if you accelerated both twins the ages would be the same, if you let the traveling twin inertial and accelerated the Earth twin at twice the speed to catch up the traveling twin, the Earth twin would be younger.

[@m.c.4674]

@@lukasrafajpps I meant that the twins are moving at constant velocity in opposite directions , then turns and accelerate at the same rate towards each other . Acceleration + velocity causes total time dilation, asymmetry does solve for who should receive the velocity time dilation when they were moving at a constant speed. Basically I am asking by what amount are they asymmetric , because you can't have too different results at the same time.

[@boyanfg]

@@m.c.4674 Hi MC, you just changed the twin paradox into a triplet paradox. Person 1 stays at the starting point of the voyage at rest, and person 2 and 3 are accelerating in different directions. They travel at high speed and return to starting point. On return of person 2 and 3, person one is older than both.

[@lukasrafajpps]

@@m.c.4674 when they move in opposite direction they both see each other as younger, when they both accelerate back at the same rate, they both see each other as older suddenly after acceleration. But as they are moving back to the same spot they see each other aging slower and they arrive exactly at the same age. It would be nice to create animation about this as it is not simple to explain in text. Remember, paradox is only a paradox if they meet claiming both are older or younger. Comparing ages when separated by distance has no meaning because the two twins have different simultaneity planes.

[@m.c.4674]

@@lukasrafajpps Only one age can be physically true , so does the universe just randomly selected one of the twins claimed age to be true or does the universe always select the same twin claimed age to be true . Eg twin 1 claim twin 2 to be 3 days older , and the twin 2 claims twin 1 to be 1 day younger . You still need to choose an answer, a result can be chosen randomly (without cause / magic) , or the same result can be chosen every trail, but then you will have a preferred frame.

[@orisphera]

Acceleration as classically defined indeed is relative. Absolute acceleration should be defined in a slightly different way. One option is to define it as the acceleration in the inertial frame tangent to the one tied to the body. By “tangent”, I mean one where the velocity at that moment is 0. You can also compute it in a way involving the differential of its four-momentum

[@ipaulino84]

if one were to make the system of four springs described in the video so big as for it to suffer the deformations caused by a body accelerated to a velocity close to that of the light, would such a system not deform when accelerated to such high speed, so that the forward spring would be much closer to the center and the backward much more distant from it, remaining so even as it were no longer accelerated, but in constant speed, so that one could not say which configuration of the system were not suffering any acceleration, if the initial were all springs are of same length, if the final, where no springs would have the same length?

[@lukasrafajpps]

Well even if in motion different observers would be able to distinguish what is length contraction and what is force as in length contraction both strings in the direction of motion would contract including the whole aparatus and the mass in the centre whereas under the influence of a force one string would contract and one would lengthen while the aparatus would maintain the length as well as the mass in the centre. Also in the force case: the mass in the centre would not be in centre anymore :)

[@Tore_Lund]

Regardless, Dialects' videos are very interesting. Love when my possible misconceptions of Relativity are challenged.

[@lukasrafajpps]

true

[@nadirceliloglu397]

Interesting but complete nonsense. Challenging does not mean making rubbish arguments which have no scientific bases.

[@Tore_Lund]

@@nadirceliloglu397 When Flat Earth seemed to take over KZbin a few years ago. I bothered to properly argue more of them in the comments, by asking scientific counter questions. I learned that I myself had a few misconceptions about classical physics, they moment I had to use science to argue. Very healthy. I learned more about orbital mechanics than I thought I needed.

[@nadirceliloglu397]

@@Tore_Lund Believe in´ real Physicists, not in some pop scientists. If you are not a Physicist, it is usesless to learn physics yourself or through you tubes, as you also need calculus, algèbre, differtial geometry. Dialect is à mickey mouse you tuber whose only aim is ; 1. Undermine Einstein's mind blogging theory of relativity 2. Critisizing other you tubers without bringing any solutions.

[@m.c.4674]

Now that I think about it , wouldn't conservation of momentum also apply for the velocity after acceleration ? If we say the rocket is not moving after it was accelerated , what happens to momentum?

[@lukasrafajpps]

well, in the frame of the rocket before acceleration, a nearby star has certain amount of momentum which is its mass multiplied by the relative velocity. If the rocketship accelerates, the star would have different relative velocity. This means that in the frame of the ship, the total momentum of the system changed but it can't happen. In the frame of the star, the ship will have different velocity but there are also exhaust particles with opposite direction of velocity and since the momentum is a vector quantity, vectors of opposite direction can cancel out leaving us with net zero change of total momentum.

[@m.c.4674]

@@lukasrafajpps You said that absolute acceleration can be determined using momentum conservation, but if I can determine that I am absolutely moving in a certain direction, wouldn't I have an absolute velocity , because conservation of momentum would still apply after acceleration. So to maintain conservation, the rocket needs to be the one with the velocity.

[@lukasrafajpps]

@@m.c.4674 No, because you don't know your state of motion before acceleration. What is you were moving and by acceleration, you stopped? By acceleration, you change your velocity relative to all inertial observers but after acceleration, you are no different from any other inertial observer.

[@m.c.4674]

@@lukasrafajpps I am confused, you said that acceleration is absolute, so why would the change in velocity be relative ( in other words , relative acceleration) . I think that , from the frame of reference of the a person observing the rocket , momentum is conserved after collision with the rocket and it's gas. But it is also true that the star has a greater momentum relative to the rocket , while the person observing the rocket would say the star has no momentum , and it is the rocket that has the momentum.

[@lukasrafajpps]

There is a misunderstanding. The fact that someone changed its momentum and therefore accelerated is an absolute fact. But after acceleration, the same laws of motion apply to the accelerated frame and non accelerated frame.Meaning you someone accelerated and you have no acces to the history, you would not be able to tell someone accelerated. You need to know the state of motion of the bodies before and after acceleration and only then you can tell who accelerated. So even though the rocket accelerated. In its frame of reference, the star really has greater momentum and it is real. No different from any other momentum. It is just the fact it gained the momentum without any cause means you were not inertial whe whole time.

[@wieslawpopielarski8974]

And the last one. In other video muon observation is mentioned as absolute prove of SRT. But problem is that muon is not accelerating at all. Just pops up with its velocity. That what dialect is pondering about is which clock really shows "true" time.

[@dannylad1600]

Great video. Im glad someone addressed this, i too was suspicious when he dismissed accelerometers. I left a comment on one of his posts asking him to address this, however the only replies i got were from his followers saying how Einstien also claimed acceleration is not absolute. I dont know if thats true ir not tbh?

[@lukasrafajpps]

Einstein had troubles with acceleration but for a different reason. It was due to existence of gravity in which accelerometes would not work as gravity pulls uniformly. He said that you can only define a relative acceleration in this case but then he argued how to solve this issue an I cite "One arrives at the differential equations that determine these quantities by means of the hypothesis that the conservation of momentum and energy must hold for material events and the gravitational field taken together. This hypothesis subsequently constrains the choice of spacetime variables without thereby evoking again the epistemological doubts analyzed above." basically saying that by including conservation laws this problem of relative acceleration dissapears.

[@Soeroore]

Nice to watch your vidio, thanks.

[@jonathanhockey9943]

Curvature is variable in GR. There is no container space. So GR cannot resolve the issue of what an absolute acceleration may be relative to, and it doesn't even claim to, it just appeals to the equivalence principle, but this only applies locally.

[@_UnknownEntity]

From the two videos of Dialect that popped up on my feed, what I've seen is, whoever is behind that content starts off by stating an incorrect interpretation of something (e=mc² for example), and then the rest of that video is based entirely off of that axiom.

[@caveman36]

The observer in earth also sees that his spring shows an acceleration in the down direction. Assume the space going twin travels at 9.8m/s^2 in a curved path such that he returns to earth eventually. The quantity of thrust remains the same but the direction changes. So now both twins accelerate the same amount, but one experiences a change in direction. How does this affect the paradox. Which twin is older and why?

[@lukasrafajpps]

these two effects are not the same. The rocket observer experiences a uniform gravitational field that spans the entire universe whereas the Earth observer experiences a gravitational field that decreases with the second power of the distance.

[@cermet592]

Any time an object changes direction (i.e. experiences a force or aka acceleration) then their time dilation changes as well. A satellite in geocentric orbit has a very different time dilation experience (constant direction change but stationary to the earth observer) than a person under it on the ground - that person see's a stationary satellite but his and the satellite's clocks run at different rates! This is easily seen from GPS signals and must be corrected for to get a correct location on the ground.

[@alexjohnward]

The twin that leaves earth must experience a higher than 9.8 acceleration to do so.

[@saxtant]

General relativity requires a relativistic definition of inertia, everyone seems to have ignored Mach's principle, which provides it for general relativity. Locality of matter density surrounding an object. This is also how you arrive at gravity in a relativistic universe, it's rotational motion when all motion is relative, the inertia of a spinning object spins opposite to it's motion. No joke, gravity is just the kinetic energy of matter rotating. The real question is why matter being spun with constant acceleration by the strong force. Gravity is just because inertia itself is time delayed by relativity forcing the speed of light. General relativistic time dilation is the reason why objects made of matter spin more slowly in an accelerated frame, because the electrons still are limited by the speed of light when they move both around a nucleus and also being accelerated by outside matter using the electrostatic forces. The combination of the 2 accelerations for matter answer all of the relativity questions, including the twin paradox. General relativity actually encompasses special relativity. The whole idea of an inertial frame was to make the math possible, but that's before Einstein understood general relativity, so special relativity can be misleading because reality doesn't have any inertial frames unless you pay attention to Mach.

[@5ty717]

Very insightful and very clear. The strings are springs по англистом

[@leokovacic707]

I think something like this( akin to the symmetry of laws if physics) has been mentioned to him in the comments without reply . However i think that such a need for a redefinition of an inertial system still is kind of a big deal as it still means that newtons postulates are indeed as circular as theyve always sounded ,at least to me. But i think there are still sime epistomological problems with this. From a math physics perspective you cant rely in measurments for your definitions ( accelerometar ) . Also the momentum conservation definition might lead you into issues with locality , and doesnt it also make noethers theorems kind of mute . You could still derive them but then you need to know the forces and round in circle we go again .

[@lukasrafajpps]

what is the problem with locality in the first place?

[@tyedee7552]

@@lukasrafajpps Assume that the information about an object's absolute acceleration at a given time t is a(t), and that information about a(t) is restricted to only that object at time t. That is, information about a(t) can only be determined by an observer AFTER time t, since information can't travel instantaneously. This means that absolute acceleration is a local effect. Now whenever you observe an accelerometer, you are not observing it how it is in the present moment, since such knowledge would violate locality. That is, observing an accelerometer can't tell you about your present acceleration. If it did that would mean information about your a(t) vector would need to be transmitted instantaneously to that accelerometer, which violates my above assumption, and the accelerometer would have to transmit that information back to you in order for you to observe the state of that accelerometer. Even if my above assumption could be reasonably objected, by saying that all acceleration must have a definable cause(a force like electromagnetism or firing a rocket), this still leaves out the fact that information would still need to transmitted from an accelerometer, to you in order for you to determine your acceleration. Again, since information has a speed limit, this means you are only observing your past acceleration, not your present acceleration. Therefore, knowledge of your own present acceleration would violate locality.

[@kylelochlann5053]

@@tyedee7552 So knowing the accelerometer reading a few nanoseconds later is an issue because... why?

[@GodwynDi]

@@kylelochlann5053 3 months and no answer.

[@luciengrondin5802]

IMHO inertial reference frames are an empirical reality which kind of contradicts the principle of relativity indeed. Not all motion is relative, as inertial frames are special for some reason we don't quite comprehend.

[@maximusideal]

I have some questions I have been mulling over. I apologize if this is burdening you given that there are so many other commenters occupying your precious time, but I'd appreciate your input. In the Newtonian framework, an apple falling is undergoing acceleration while an apple on the ground is not. In GR, an apple falling is not undergoing acceleration (because it follows geodesic motion) while an apple on the ground is accelerating upward. So far, I completely agree with the above as correct! Various science popularizers (Sabine Hossenfelder, Brian Greene, etc.) have been saying that the latter is the "more correct" view since GR is the deeper theory. However, I am mulling over this and I have some doubts. 1. First, I see the transition from the former view (Newtonian) to the latter view (GR) as being much more "brittle" than, say, the transition from geocentrism to heliocentrism. The reason I say this, is that there are various background-dependent theories from QFT and quantum gravity that restore flat spacetime. If any one of those theories gets vindicated, does this mean we have to reverse our stance as to what is the "more correct" viewpoint? 2. At the end of your video you point out that momentum conservation requires you to look at the symmetries of spacetime. By extension, this means we have to consider the structure of spacetime. Accordingly, what is considered an acceleration and what is not an acceleration seems to depend on the structure of the spacetime. However, it also seems to me that the structure of spacetime depends on the framework/theory you adopt. I agree GR is a well-tested theory, but I don't know of any empirical data that forces us to adopt a certain kind of spacetime structure (except maybe in cases like black holes or cosmology where the topology of spacetime itself is non-standard), as opposed to possibly treating gravity as some kind of field theory in the future (as Steven Weinberg seemed to suggest in some of his books). 3. Some theories like Kaluza-Klein theory say that electromagnetism is a manifestation of gravity. In that case, would the apparent acceleration by electromagnetism also have to be reconsidered as not true acceleration? My main issue is that I see the questions of "what is and is not acceleration" and "what is the spacetime structure" as both being framework-dependent. (However, I agree that once we choose the framework, everything is fully well-defined.) It also seems to me that perhaps we need to wait until a further generalization of GR (like quantum gravity) could shed further light on what really is the "more correct" viewpoint. However, I'm wondering what are your thoughts.

[@lukasrafajpps]

Hi, I am not sure I understand the question correctly but I don't know about quantum gravity but in qft, there is not a static background. Each inertial observer see the same background so it is not dependent on the velocity. If you are under the influence of a force, the background is different from inertial observers and by this you could know you are accelerating but the background does not evolve in time therefore at each instant of time you can't say anything about your current velocity only about your current proper acceleration.

[@SpacetimeTraveler-p4e]

The free-fall apple is not physically accelerating in either Newtonian or relativistic physics. The absence of free-fall acceleration is a measured fact of nature and independent of any particular theory. The free-fall apple has the same coordinate acceleration in both Newtonian and relativistic physics, as does the apple on the ground. There is no distinction whatsoever between relativity and Newtonian mechanics.

[@TheOneMaddin]

You said: we only need to define momentum without using inertial frames, and you propose to do it using velocity times mass. But how you gonna define mass? Do you need force? Then you need acceleration. Do you use gravitational attraction? I am not sure you wouldn't run into any circularities here, but you certainly loose the ability to test the equivalence principle. So what you gonna do?

[@lukasrafajpps]

I don't think you need to have an inertial frame to define mass. Mass is just resistance to change in movement whether it is under acceleration or not. I think the correct interpretation of F = m*a is that force causes acceleration not acceleration causes force. Yet a different problem is that for accelerating observer, the momentum conservation is broken maximally. It means that the surrounding is accelerating to the same direction as the rocket exhaust. so there is maximal change in one direction and zero change in other. All you need to know is that the exhaust and the surroundings have not zero mass which we know from the fact they are not traveling with the speed of light.

[@pierfrancescopeperoni]

Proper acceleration is still a relation between two frames in relative acceleration. It is a property of the system floor-spring, and if you shift the acceleration of the whole system, the proper acceleration detected is still the same. The detected proper acceleration, as a scalar, is absolute, but it's not about absolute acceleration.

[@pacolibre5411]

The key misunderstanding in his video is that relativity does not necessarily reject the idea of an absolute 0 acceleration space, just no absolute position or velocity. Dialect also believes that position is relative, but that velocity is not. So the argument is not over whether motion is relative or not. Everyone agrees that some motion is relative, and some motion is not. The disagreement is only over whether the first or second derivative becomes absolute.

[@ValidatingUsername]

Acceleration is the emergent characteristic or property of the energy required for a microsystem to undergo a Lorentz transform

[@JOAOPEREIRA-nu5rw]

You are right!

[@donniewatson9120]

The only defect I've seen is that it breaks down under certain conditions, like behind the event horizon of a black hole or the answer given for required energy to have an object with rest mass travel at the speed of light in a vacuum. 1/0 is an undefined answer. An undefined answer means we don't know what is required. Just because we don't know the answer doesn't mean that it is infinite. It means we need to find the flaw in the equation to determine the answer.

[@dullyvampir83]

Isn't this basically newtons third law that for a proper acceleration you need to see an opposite force, otherwise you are observing it from a non intertial frame?

[@drbonesshow1]

In terms of the physics "up or down" and "in and out" don't matter much when we consider symmetry.

[@wesbaumguardner8829]

Acceleration is under absoluletely no requirement to be linear. In fact, most accelerations are curvilinear.

[@weeblol4050]

I still hold an opinnon acceleration is undefinable without the context of other bodies in the universe and most consequential are the close bodies. In other words in big empty regions of space you cant know if you are accelerating or not, more precisely if you dont see any stars acceleration isnt absolute.

[@internet_polymath]

I think a great argument for absolute acceleration is the fact that we discovered gravity before leaving Earth...

[@DANGJOS]

You forgot tidal effects in the gravity example. Gravity is never perfectly uniform.

[@philoso377]

There are two place we can calibrate that accelerometer : 1) in the center of earth or 2) is the center of the universe, intergalactic space is next best to the center of universe.

[@kipkipper-lg9vl]

Can you even say the universe has a center

[@philoso377]

@@kipkipper-lg9vlno one know for sure where universe center is. But we can borrow from a free drift state in the intergalactic space as an universe center in discussion. Alternatively, we can use precession of a gyroscope to detect acceleration. If we couple one end of a gyroscope axis to the ceiling of a space ship all drifting in space. Any acceleration will cause the axis to tilt. At steady state there is no precession. There is when the rocket engine fires. Gyroscope references to (sum) mass and sum gravity of the universe.

[@kipkipper-lg9vl]

@@philoso377 I'm not even sure what most of that means

[@philoso377]

@@kipkipper-lg9vl I reread my comment found a mistype word. Not sun but sum. Thanks to the auto respelling. I recommend that.

[@lucassiccardi8764]

@@philoso377 Interesting. Could you expand a little on the difference between accelerometers and gyroscopes?

[@LearningMathPhysicsLive]

I love this video! Brings up great points that refute Dialect's assertion that the accelerometer cannot be calibrated. I have two objections/thoughts. 1) Calibrating the accelerometer with asymmetry assumes we know that our frame is a non-rotating, non-rotationally-accelerating frame. Can we formulate the calibration argument for the 4 springs taking into account rotation without reference to faraway stars? 2) In my view, conservation of momentum was already "broken" with E&M, but we assigned momentum to the fields to avoid problems. See section 6.7 in Jackson, where the non-conserved linear momentum is interpreted as momentum being in the E&M fields. Why was the interpretation not that we are in a non-inertial frame or that momentum isn't conserved? If we do this every time we see problems with conservation of momentum, we will always see momentum as conserved. Are we sure that we (the physics community) don't see momentum conservation broken regularly, but instead of saying we are in a non-inertial frame or another interpretation, we assign the momentum to a field to recover conservation of momentum?

[@alexanderkoutouzis7302]

It might be a stupid remark but doesn't inertial frame simply refer to the coordinates being used to study motions? To be more precise, the usual n-dimensional Euclidean space can be equipted with an inertial frame of reference. But if you were to use the frame defined by an accelerating particle you would find that newtons first postulate does not hold. So, from my understanding, the inertial frame of reference is a matter of coordinates (and perhaps the geometric properties of the space, eg on a sphere you dont have one global coordinate system, but rather a collection of maps), therefore i dont see an issue with defining acceleration as the second time derivative of your position IN YOUR PARTICULAR reference frame. I feel like we conflate accelation in with respect to a coordinate system and acceleration of the coordinate system. Hope it makes sense.

[@edwardmacnab354]

deceleration cannot be distinguished from acceleration except through the use of atomic clocks whereby an accelerated clock will slow and a decelerated clock will speed up ( all compared to a reference clock stationary in your local frame)

[@lukasrafajpps]

decelerated clock is the same as accelerated clock also in terms of time dilation.

[@edwardmacnab354]

@@lukasrafajpps no dude they are not ! one has an energy input and the other has energy removed . When the clocks are checked. they all 3 show a different time passed. The experiment has been done already. when compared to the static clock , one was slower and the other was faster. and this is because the earth ITSELF has a static frame . When rotating , the static frame does not disappear . The rotating earth drags through the static frame and it's time slows as a result . clocks accelerated east are getting to the static frame which runs faster than the rotated frame so it is a deceleration. clocks moving west are accelerated even faster than the earth rotation and are therefore even slower. I'm sorry but we are definitely not on the same page .

[@KipIngram]

Why couldn't you just manufacture all of the accelerometer springs in exactly the same way, at the same time, right beside each other, and then build the thing and regard it as pre-calibrated?

[@narfwhals7843]

What does that solve? Then the springs are calibrated relative to their manufacturing site.

[@jmcsquared18]

I was really enjoying Dialect's videos. But over the last few months, their claims grew more and more towards crackpot status. When your videos contains phrases like "finally, we've solved the problem that nobody else has been able to solve," any good skeptic's alarm bells should start going off. The rate at which Dialect was claiming that everyone else (especially on KZbin) is wrong was the first sign to me that they have some ego issues.

[@SmoMo_]

Great video, thanks for making it.

[@EGOPON]

The long short, it all boils down to the following definition: Inertial frames are the frames where the Newton's 1st law applies (If there is no external force, the center of mass of the objects have no acceleration)

[@chenlaura5958]

Acceleration is relative. The accelerometer Physics - problems and solutions uses is a free body with springs attached to it. The problem is that it is impossible to know weather a body is free because it could be influenced to a magnetic field 400 light years away and we would not be able to tell for 400 years. The second accelerometer which rotates the spring is not good either because it could be influenced by a changing magnetic field 400 light years away. The conservation of momentum argument is also flawed because measuring the total momentum of a system is impossible. This is because of the speed of light where measuring the total momentum takes time because light takes time to reach the accelerating observer.

[@lukasrafajpps]

electric and magnetic fields travel the same speed as light. In the end light is an electromagnetic wave. Although you can use plastic spring if you want. It also doesn't matter when you measure the total momentum of the system. just track the momentum of all the particles you see at each time and you are ok

[@wesbaumguardner8829]

It is empirically observable that gravity causes motion. The problem with the curved spacetime claim is that it has absolutely no way to cause motion. There is no up or down in space. There is no mechanism to explain how spacetime bending could cause motion. Saying "it just does" is not an explanation.

[@dericksmith740]

Great. youtubers keep saying spacetime is distorted then balabala with giving any convincing argument or show any deep insights.

[@wesbaumguardner8829]

@@dericksmith740 That is because there are no deeper insights. The theory itself is deeply fallacious, nonsensical, and self-contradictory from its primary premises which causes a great amount of confusion for people whom attempt to understand the theory. The supporters of relativity use this confusion to claim to have superior intellect and feed their ego. This is just new age mysticism.

[@stevendaryl30161]

@@wesbaumguardner8829 : Or the other possibility is that you are wrong about that.

[@stevendaryl30161]

The bending of spacetime doesn't cause motion. It causes whatever motion already exists to curve. The change of perspective in going from Newtonian physics to Special and General Relativity is to view motion not as a 3-dimensional position that changes as a function of 1-D time, but as a path through 4-dimensional spacetime. To simplify, let's consider just one spatial dimension and one time dimension. So two dimensions in total. We can plot the path of a small object, such as a ball, by using graph paper, letting the horizontal direction represent space and letting the vertical direction represent time. The path through spacetime of an ball at rest is just a line going straight up. It is moving through time (that is, time is advancing) but not space. Now, consider two balls that are both at rest, but are at different locations. Their two paths through spacetime would be represented by two parallel lines, both going straight up. As you move up and down in the time direction, the spatial distance between the balls does not change. That's what happens in so-called "flat" spacetime. What happens when we introduce curvature? If spacetime is curved, then two paths that start off parallel will not remain parallel. You can see this on the surface of the Earth. If two travelers start at the equator at different locations, and travel straight North at the same speed, their paths will initially be parallel. But their paths will not remain parallel. Eventually, the two travelers will converge at the North Pole. So even though they start traveling parallel, the curvature of the Earth bends their paths towards each other. The same thing happens in spacetime. Two balls that initially are traveling parallel (both straight "up" on the graph of time versus space), spacetime curvature will cause their paths to no longer remain parallel. They will move towards each other or away from each other (depending on the type of curvature). To reiterate, curved spacetime does not cause motion, but it causes motion that is initially just in the time direction to bend so that two objects that are initially at rest will start moving towards each other.

[@wesbaumguardner8829]

Qzvva1gz

[@dimitardimitrakov2841]

These are concepts very deep and require lots of mental exercise and power to become comfortable with. I have one question for the author: can we imagine physical universe which is composed of only ONE object i.e. there cant be anything to be called "observer" of that object. If such universe is possible will it have Space? How about Time? Isnt space an emergent property from the fact that more than one object has the property called existence. ,"existence" is the property to have a property....

[@PR-tq8yo]

I must have missed something, but why is it circular? It's not. Inertial frame is not accelerating, but an inertial frame is needed to define acceleration. Again, that is not circular at all.

[@patryn36]

All motion is relative only because you need a point of reference to measure it. Seeing how everything went can see is moving in this universe getting an absolute velocity is going to be impossible. Even that device is showing that, it reacted to the gravitational pull not any sort of motion that the earth has due to its orbit, due to its place in the solar system as we orbit the galaxy, and/or the Galaxy's motion in the universe. The whole curved space/time aspect is suspect to me for the reason of gravity assist maneuvers: it is dependent on which way you go around the target body, if space was warpable then it should not matter which way you go around the target. When and if anyone ever gets a piece of space time to the point we can do things and show it off, then we can have a serious conversation on that subject.

[@narfwhals7843]

Gravity assists have very little to do with spacetime curvature. They work by taking momentum from the orbit of the assisting object. Since momentum has a direction this obviously depends on the direction of approach. This is true whether gravity is a force or spacetime curvature.

[@patryn36]

@@narfwhals7843 funny thing is every description I have heard of what gravity and what it does is directly linked to spacetime either as the reason for the curvature or a result of. Either way this being shown as wrong since you have to go with the rotation to get the boost or against the rotation to get the stabilization/slow down. If spacetime curvature was the real feature that would not happen that way, you would also be able to account for star orbit speeds on galactic fringes. Every visual representation done for gravity was a bowling ball on a sheet type thing, and yes I know the difference between essentially a 2d representation of a 3d effect.

[@narfwhals7843]

@@patryn36 That's because the term "gravity" is ambiguous. Some people use it to describe the property of matter that curves spacetime. Some use it to directly mean spacetime curvature. And some use it to simply mean gravitational attraction. Motion in curved spacetime is the reason for gravitational attraction. Gravitational attraction is what you need for gravity assists, it does not matter for the result whether this is caused by motion in curved spacetime or a newtonian force. The directional dependence comes from the direction the assisting body is orbiting around the sun. This is expected from aspacetime curvature description. Visual representations of 4d spacetime curvature are intrinsically misleading.

[@patryn36]

@@narfwhals7843 I do not see how gravity is ambiguous, seems pretty cut and dry of a concept. The whole warping of spacetime does seem ambiguous especially when you consider that they managed to quantumly entangle photons which slowed them down and showed they have mass. Or the fact we have not seen black holes under the minimum mass limit yet. As far as I can tell, the whole spacetime thing is an artifact of trying to make sense with extremely limited understanding of a handful of decades ago. Problem is using that concept is holding progress back while misleading the efforts.

[@kirkpetersjr]

Cleared up some thoughts

[@philochristos]

If you were in orbit around the earth, would you feel an acceleration? I mean wouldn't you feel like you were in zero gravity?

[@macfrankist]

After shutting off your rocket the spring extends and your conclusion then is that the spring is experiencing a force? Did you forget that you turned off the rocket??? Give me a break. Love your work btw..

[@jimjimmy2179]

Hmmm, the momentum conservation thing only ever shows relative to other things. And it's only ever related to the object mass and its relative speed against other objects. E.g. an object momentum has nothing to do with the object acceleration ,providing the dv is taken to account for objects where elasticity cannot be ignored but this applies regardless of the colliding objects accelerated before collision or not. The overall momentum is always conserved. Now if we have an external force vector (which is why one or more objects accelerate at the first place) then the overall momentum of the colliding system must include this vector for the overall momentum to be again conserved. However this is the resulting vector of all individual forces acting upon colliding objects which might amount to an empty vector. Moreover accelerating frame isn't defined by dv/dt but by an F != 0 acting upon it. Hence the Einstein notion that even though one standing on the Earth experiences dv/dt = 0 but F != 0 one is said to accelerate. On the contrary the free falling object is in fact at rest.

[@dannylad1600]

I dont really get Dialects argument about accelerometers not giving you a true measurement of acceleration? If for example you take a simply supported steel plate that's spanning 1 metre, the plate is 300mm wide by 3mm thick, grade S275. If this plate is subject to zero acceleration, ie if its in freefall it will measure zero defection midspan. If its subject to say an acceleration of 9.8m/s/s perpendicular to its span, like any object sitting on earth, then it will measure 4.9mm midspan deflection. If you ramp up the acceleration to 20m/s/s then you get a deflection of 9.9mm. Surely this is a direct measure of acceleration? He would argue how its been callibrated though, but thats what i dont get because surely 0 defelection equals 0 acceleration in this case?

[@lukasrafajpps]

dialect argument would be, what is 0 deflection? you have to define 0 deflection in inertial frame but how do you know which is inertial? of course I don't agree that you can't know as I argue in this video.

[@dannylad1600]

@@lukasrafajpps, well my argument to that would be, 0 deformation from its original shape at the point it was cast from molten steel in its mould in the factory it was made. If the plate was cast into a flat mould, then any deflection from this would require a force therefore an acceleration.

[@lukasrafajpps]

@@dannylad1600 but the factory can or can not be under acceleration so you don't know whether it is already accounted for when you create the plate. Of course, you can rotate the plate in different directions and see how it changes if the shape depends on the orientation, then you know it is under acceleration. The point is that you have an acces to another dimension and since acceleration is a vector then it is easy to detect it. The interesting question would be whether you can create an accelerometer in 1D based on some sort of spring. And that is more tricky because acceleration in 1D is a scalar not a vector and therefore it has only a magnitude but not a direction. Here it is a real problem to calibrate such accelerometer. However, the conservation of momentum must hold for inertial frame in 1D as well and therefore you could calculate the momentum of all the particles nearby in time T and then again later in time T' and if the number is the same you are in inertial frame. Of course provided we are talking about real physical world where simple particles can't undergo an acceleration without any cause.

[@ozymandiasultor9480]

A very good, concise explanation of why the "Dialect" was wrong! You have a new subscriber from one (relatively) small country in Europe.

[@sleethmitchell]

my intuition is fine for everyday things. our explanations are intended for everyday things. the large, tantalizing problems for me are these relativity theories. and the reduction of causality to probability in the quantum theories. my brain is fine for survival; it seems to falter when stretched too far. still, it's fun.

[@Deutungshoheit]

I like his videos a lot, but I was thinking the same about his argument against absolut acceleration. Acceleration can’t be completely relative because of inertia. If the frame of reference for acceleration didn’t matter at all that would mean the rocket engines could move the entire universe. But that doesn’t make sense because it would take way more energy to move a planet let alone the entire universe compared to moving a space ship.

[@phillipcoetzer8186]

I got thinking ... everything is in motion So a ship floating in space is in motion if it fires thrusters in such a way that it decelerates it will feel all the signs of acceleration and the effects that go with it

[@philoso377]

Remember - Whatever an observer perceived in this universe however strange real or logical, remains to be a creator of his own imagination but creator of this universe.

[@cm5754]

Of course, it doesn't matter whether we can measure the acceleration on one twin - only that there is actually some physical difference between the twins. The paradox appears because we can change coordinate systems so that either twin remains stationary the entire time. So breaking the paradox just requires the existence of some actual phenomenon that the change of coordinates doesn't respect. It wouldn't actually matter if that phenomenon is measurable in any particular way.

[@nickr7437]

I take issue with hand waving away gravitational acceleration by just mentioning curved space time. It doesn't actually take away from the issue of whether or not we can truly define acceleration, and whether we can declare it absolute or relative. For every observer in the universe, they see an object falling into a gravity well as accelerating towards the center of mass. This is acceleration according to the observer's coordinate system. The fact that the object falling into the gravity well can't detect it is in fact the best evidence that we have no true knowledge of our state of acceleration. The issue of universe expansion is no different. There may be many unknown types of physics accelerating us relative to other frames, that we have zero physical indication of. Gravity and expansion are just two known types of this. So I find it crazy that anyone think we have the ability to declare anything about the state of acceleration of any object.

[@mpcformation9646]

Forget about « Einstein-Mileva » view point, they made a mess of Poincaré universal Relativity theory, without understanding not only his maths and physical principles, but not even what they were themselves righting and which is indeed a forgery. Poincaré didn’t mess up with « inertial frames ». He based the entire theory of Relativity on his 1890 clocks synchronization algorithm, and on his 1895 universal principle of Relativity, which is not about « inertial frames » but about changes of coordinates, changes of view point. It’s a mathematical relativity, a model, that he applies to Physics, technically at relative speed zero. Than uses the Lie algebra structure of the Poincaré-Lorentz group to cope with acceleration (thus any speed) which are perfectly valid in Relativity. Einstein knew nothing about Lie group and infinitesimal associated transformations. Thus he made a mess of Poincaré universal theory of Relativity. So there is in a sense an « absolute acceleration ». Indeed, such « objective » acceleration is defined as the proper one. The rest is « subjective » and is what others would say about it without being able to live it. It’s a mathematical description, a « subjective frame observation ». But the only actual acceleration that has physical meaning is the proper one. The rest is view points, not actual physic.

[@sistajoseph]

Acceleration can be relative or it can be absolute. They are some little issues, the problem of what constitute movement or what moves, is still up in the air. The other issue is, acceleration of what? As a concept, the change of velocity, it does not matter, relative or not. Acceleration of mass is another issue. Then we need to decide, what is mass and what is the movement of mass. The theory of relativity specifies limits on acceleration but if those limits are correct, then acceleration is relative. It must be relative to space, if not, how would the laws be enforced? Here is an example, there is some kind of law that specifies the acceleration of an object falling in air under gravity. There is some kind of limit there. We know that acceleration is relative to air and the law is enforced via a micro process that involves air. Relativity itself is a macro theory, it does not say anything about molecules or atoms or anything of that nature. Doubtless, such things do exist and we do not know what is the bottom of that abyss. Notwithstanding that, we will not be foolish enough to say that relativity is enforced by magic, there is a micro process that we do not yet understand.

[@juleskurianmathew1989]

No, accelerometer can not detect absolute acceleration. If u r on a closed spaceship in deep space, and if u make an accelerometer out of raw materials on the spaceship, u will not detect acceleration on the accelerometer! On the other hand, if a foreign accelerometer made on a foreign planet or spaceship is introduced into the aforementioned spaceship, it may detect acceleration depending on whether the foreign planet or spaceship is accelerating or not with respect to the spaceship in question. What do u mean by calibrating an accelerometer with respect to a frame? It means making an accelerometer from raw materials found on that inertial frame. For instance, u make an accelerometer on earth. Now u take it in hand, and step inside a bus. As soon as the bus accelerates, it will detect acceleration. That's because the bus accelerates with respect to the earth! The accelerometer considers earth to be at rest and therefore it detects bus' motion with respect to this reference frame of eatth! Actually, earth is indeed moving through space. It is not an ideal absolute reference frame. Does an accelerometer made default on earth detect acceleration of earth itself? No! If it would, only then absolute acceleration exists. The fact that it does not, suggests that acceleration is relative! Things become different once u add gravity into the picture as in general relativity. In such an example, suppose u make an accelerometer in earth at a point A on earth's surface. A crane lifts u (with u holding the accelerometer) up high to point B in the sky. All the journey up to the point B, the accelerometer would show deflection. When the crane suddenly releases u, u r in freefall. The accelerometer in ur hand would not show deflection. So u may ask why doesn't it show deflection. It should, right? Because the accelerometer was calibrated with respect to earth and an object in freefall towards earth is accelerating towards earth, right? No, an object in freefall to the earth is not in acceleration with respect to earth. It was simply moving at uniform motion along its geodesic in spacetime. U may ask if the object and the earth follow their own respective geodesic motions and therefore r not accelerating, then why r they meeting each other? Well, that's because the spacetime is weirdly curved and twisted in the vicinty of mass. Its a complicated concept to wrap our heads around. An object in freefall or an object lying rest on surface of the earth have zero relative motion with respect to earth. It is just that their geodesics meet because of curvature of space. It has nothing to do with acceleration as in the euclidean flat spacetime.

[@anywallsocket]

we should be sure to not try and make absolute sense of 'paradoxes' which involve unphysical events within the very physics which supports physical events

[@cermet592]

Excellent video and great points - I am glad someone like you with a deeper knowledge can address such issues. Yet there are issues that one must accept about general relativity (GR) - it does not incorporate quantum mechanics and has the issue with singularities. So GR does have issues and one can not dismiss that a deeper theory is required: i.e GR isn't correct.

[@cermet592]

I will add I think these issues can be resolved but I'm just saying the obvious point that GR is not in agreement with QM. As for the singularity issue (more a math issue but it appears in GR), that is just too much fun and makes me rather amused (esp. the ridiculous methods certain physicist use to treat the inside of a Black Hole - 100% nonsense since it is never falsifiable! That isn't science at all.)

[@lukasrafajpps]

The singularity issue is only where R goes to 0 for example in the Schwarzschild case. but it does not mean it is not correct in the regions around this point. Newton theory also has a singularity of this type. The GR also has an apparent singularity when you cross the event horizon of a BH but this singularity is not real. It is caused by inproper choice of coordinate system and therefore if you chose it differently you can avoid it. I kinda struggle however to fully accept that one can just pass through the horizon into the "singularity" since there is an extreme time dilatation as you approach the horizon for the observers at infinity and those exact observers will see the BH evaporate in like 10^70 years therefore sooner than it takes you to fall inside. from your falling point of view it would mean that it would evaporate very quickly as you are falling inside. But I am not expert on blackholes so I don't know

[@kylelochlann5053]

Yep, you're not an expert on black holes. It would be a good learning experience for you take well-known textbooks (Hawking&Ellis, MTW, Wald, etc) and look up gravitational time dilation. They're freely available online.@@lukasrafajpps

[@kylelochlann5053]

@@cermet592 Why do think GR and QM are not in agreement?