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

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!

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

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

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.

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.

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.

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.

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.

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

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.

Your accent is a weird mixture of Slavic and German, I love it!

Acceleration is invariant. Everyone agrees on who is accelerating and by how much. That's from Newton, not Einstein. So, in the Twin Paradox it is obvious that the spaceship is accelerating back towards Earth. Both Earth twin and Traveling Twin agree on how much and which direction that Traveling Twin is accelerating at the Star. A force is a force, of course, of course!

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.

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.

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.

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

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.

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

Dialect and this fellow are a gift that keeps giving !

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.

I just love him the way he humiliates the others with logic 😅😂

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

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

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.

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

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.

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.

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

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.

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.

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.

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.

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

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.

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.

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?

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.

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.

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

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....

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.

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?

❤dialekt vs physics - problems & solutions❤

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.

dialect got dissed

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?

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

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.

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

Nice to watch your vidio, thanks.

Hi Lucas, Your videos are enjoyable indeed and correct, not like Dialect's videos full of flaws. I have watched your video and agree with most! Let me give you my comment on how we difine inertial and non- inertial frames. It is obvious that Dialect has this completely mixed up. It is easy to define inertial frames and non-inertial frames. Inertial frames are anisotropic when it comes feeling no force. No force on you is acting in any direction in an inertial frame. In a non- inertial frame, you feel a force which acts in one direction. Proper acceleration can be measured precisely. I dont see any loopholes in defining inertial and non- inertial frames. Newton used the same definition and Einstein also. When it comes to acceleration being relative or absolute, in SR,it is absolute,but when Einstein developed the General Relativity, he postulated that there are no absolute motion in the universe. All motion is relative , including acceleration.

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?

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

Each and every velocity is INFINITELY relative, and this includes momentum. Naked velocity DOES NOTHING in physics. Infinite definitions also means no definition. Acceleration is agreed upon by all observers making it absolute, and this INCLUDES gravity. Gravity is a static absolute, and acceleration from some cause is the dynamic absolute. Gravity is centrally directed, and Einstein MISSED THIS POINT. A large frame can tell the difference between gravity and linear acceleration, because there is a component of acceleration toward a center of mass which is more of a triangle, not linear. It is a MASSLESS medium that seeks to contain mass and resists CHANGE. I do like your circular calibration idea. That concept is very close to my version of how massless space reacts to change. All mass displaces the ether making a dent, and your circle is that dent that mass MUST be centered in, or it means change. Gravity is consolidating MANY dents into a larger dent. The dent is tension or energy, and this is where CAUSAL physics begins.

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?

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.

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

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

Everythink is based around an accelerometer: hjowever i believe this is fundamentaly wrong too. Whenever a force is applied it isn't felt because it is applied not-absolutely uniform. Thus if i push you, part of you is pushed, part of you isn't, you feel the different areas deforming. The same thing will happen if accelaration is done by electricity or whatever other means, except from gravity. True? Well not exactly. I argue that the same effect or feeling applies also in gravity, it is simply too small to be felt by any practical device, but theoretically it CAN be felt as any other force. Assume our accelerometer is 1.000.000 km longs. The edges of the device will be so much closer to the gravity source than the outer edges, so some streching will occur and our device will register change in motion. So, since everything is based around accelerometers and if we feel the force of gravity or not, i haven't read anybody discuss this thought.

This explanation is so good! Thank you very much!

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)

Is this only one reaction to dialect in entire youtube?

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.

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

Excellent. :)

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?

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.

"Proper Acceleration is acceleration relative to the free-fall". Interesting. Very interesting... 🙂

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 .

Why not simply use the twin paradox for the definition of inertial motion? (Timelike) geodesics are local maximizers of proper time, problem solved.

Dialect logic was similar to the fact that you can never tell what is the actual frequency of light from a source untill you are sure either source or observer is at absolute rest which is a thing that doesnt exist as per Einstein himself.

Really wonderful explanation. Clear, concise, accurate, non-judgemental all in not your native language. Really impressive. Thank you!

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.

Cleared up some thoughts

You are right!

I like your definition of acceleration, which is a frame that doesn't conserve momentum. What if we define acceleration as a deviation from a geodesic? If anything deviates from a geodesic trajectory, it's accelerating. And there is no circularity since a geodesic is the shortest path between two points on a manifold.

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?

Light does not accelerate. The dot a laser creates on a far away object may travel across that object as you wave the laser around, but there is no physical acceleration involved on that object. Similar to that, a photon is a property of the space it travels through. There is nothing there to accelerate, which is why it can be a particle and a wave simiultaniously.

Incidentally, as a consequence of your clarity of mind about special and general relativity theory, I want to ask a concrete and illuminating answer to the following question: what kind of space/time distorsion could cause a so conspicuous change of velocity (9.8 m/s every second) of a particle falling into the gravity field of the earth (a relatively weak field, indeed)… please, do not be too short…

Everything is time traveling relative to everything else in a different inertial frame of reference.

the @dialectphilosophy videos make me fell that I'm somewehere between a new era of physics and the most elaborated crackpot material produced by man.

I'll just wait and see how your channel grows in subscribers, you have great content!!! Thanks

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?

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.

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?

Dialect complicates things by making the assumption that we cannot have certain knowledge of our system beforehand. Let me explain. In particular, why can't we simply presume which particles are free particles and which particles are not free particles?? For example, with the accelerometer, dialect says "unbeknownst to us, the accelerometer is in an accelerating rocket ship." Hence, we cannot assume beforehand whether or not the accelerometer is a free particle or not. In practice, we'll know whether or not an accelerometer, or any other object, is in an accelerating spaceship. He claims that the twin paradox remains unresolved because we cannot know which twin is truly doing the accelerating. Well I thought we can simply assume that a force is being applied to one of the two twins and the other twin is a free particle. If we cannot assume whether or not a force is being applied to a particle, then all of physics is in huge trouble.

Am i looking at a RU-vid war in physics teachers? Jajaja

Yes 👍inertia mass value would in fact grant relative and deterministic unification within the non locality gradiant. But of course this pushes complexity onto space/time and large scale models. And evolution is a religion that many have held since the days of Assyrian kings. only under war time powers and the heated exchange of the times do we get trapped back under the dualistic chaldean mind model again. classical American founders was very keen on newtonian physics infinite sums of approximating complexity that classical mechanics tells us cause & effect of unification here means complexity there. They invoke the triality, grant the individual ben Franklins systems unification on this principle that mechanics & technicians was where everything matters . Dualistic newtonian nature with the triality individual navigating it with simplicity pushing the complexity up the higher archy where it belongs

Thank you!!! Dialect is so haughty

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?

Bro I hate to point this out but by your logic, any part of the ENTIRE universe is an inertial frame lmao the law of conservation of momentum requires you to conserve momentum regardless of where you are in the universe for a closed system. Your system you are describing is closed no matter the reference frame, therefore you think both are inertial frames and breaks your own logic 😂 how did you not see this man?? You only proved symmetry of both instances not the asymmetry

Great video!

Don't bump your head!

none of the rockets accelerate, we redefine one of the rockets by removing the yeeted particles from the definition of it's com position. if we keep considering it as a whole with those particles, it's merely changing its shape. then we can calculate the time difference between this inert but lopsided rocket and its particleless main part relative to each other. there. we have our acceleration nonabsolute. now kiss and make up.

Briliant!

I am happy to see these discussions because it helps us all understand the subject better. I see your point but I do have a question: from what I understand, an orbit (without any rockets or the like) is usually considered to be inertial. If, by extension, a u-turn half orbit (assuming all masses and initial velocities are tuned properly) can also be inertial while having the same speed going in as coming out: what happens with the twin paradox if they start out moving away from each other at a certain velocity and one of them makes such a u-turn assuming a (near) zero velocity between the star and the other twin for simplicity? Which twin will be older? We do have a simultaneity problem in this case so it's hard to know when to start the timers but that would account for only a very small amount of the total time difference of this problem relativistic speeds and great distances.

Be ready, because sooner or later Dialect will answer you. But you're right, don't worry ! 🙂🙃🙂

yeah he says some not quite right stuff in there, but it isnt wrong in the following sense, a lot of people talk about the equivalence principle as if it is actually real. which is silly, on the surface of earth you are not being accelerated upwards, if that was the case there would be no tidal forces. but some physicists and a lot of ley people think that is litterally true. the theory just says some shit that is unambigous, i dont care beyond that, i dont think it really matters unless you phrase everything as relational, then you have to worry about these concerns of absoulute acceleration and so on. btw if you ignore tidal forces what people say is that you are being accelerated with respect to inertial frames, which are falling frames because of the geometry, that is nonsense, that is one way out of many to think about what GR says. sometimes i think we should shut up a bit more and talk about what a theory says only if we can bring ourselves to not tell stories that can be told with the same level of accuracy with respect to the math in 57 different waysas if it were somehow more true than the other explainations that maps just as well onto the math, in this case the math of GR. think about this, in newtonian physics you can put in a uniform gravitational field and nothing changes physically, that is also true in any theory, and approximatley true for a very non-uniform gravitational field, that is the only sense in which absolute acceleration is ambigous, it is true that is it, but it is unavoidable unless motion is absolute, with respect to all the stuff you define physics through ina fully relational picture of every detail of physics. until that is realized it is all talk anyway.

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?

Do you have a name? Website?