Steve3007 wrote: ↑September 14th, 2018, 1:59 amperhaps it should have instead said that the concept of aether doesn't add anything useful to physics because it doesn't affect any observations. That doesn't stop people from postulating the existence of such a thing. But a concept which doesn't, either directly or indirectly, predict a possible observation to be different than if that concept wasn't used is of no use to physics.
It is a demonstration of the existence of the dogma that you deny exists. The aether (space fabric) is of great use to physics as it is required to make theories rational. Your rejection of it is fuelled entirely by the dogma and irrational thinking (i.e. bad philosophy).
The first postulate is not ambiguous if you understand what laws of physics are. Laws of physics are generalizations created from observing the patterns in measurements which predict future measurements. The first postulate simply predicts that those measurements, and therefore the laws of physics that derive from them, will be found to be the same when measured against any non-accelerating reference frame.
But most people take it to mean that because the speed of light is represented as c relative to any frames, that is the actual physics too. There is nothing there to tell them otherwise, and almost all of them understand it that way. The ones who don't are deviating from SR as it is normally understood - they are bringing in an absolute frame which is ordinarily banned.
I think misunderstandings of these kinds of explanations often come in if you read them in isolation without doing the groundwork first.
I think you're the one misunderstanding them, because almost everyone out there in the real world interprets them the same way I do - if they didn't, they'd all accept an absolute frame.
I agree that aether shouldn't be rejected as a problem. It should be regarded as not necessary to the purposes of an empirical science. It isn't a problem, as such, because it always seems to ensure that it can't affect any observations.
The more important issue is the absolute frame, and that is necessary to avoid contradictions, unless you're very specific about which model you're using that renders it irrelevant and make sure that this doesn't also get carried across to other models where an absolute frame is logically required. Separating out the different models and setting out the rules for each of them should be a requirement of everyone out there who's educating people about what SR is, because if it's done without that rigour, we get miseducation on a massive scale.
If one frame says something is stationary and another says it's moving, it is clearly impossible to tell whether something is moving or not, so your objection to that one is frankly ridiculous.
Which is perhaps one reason why frames don't say that. Movement is defined as the change in the spatial distance between two objects with respect to time. So, if you use the correct definition of the word "moving", clearly we can work out if we're moving.
Frames do say that. You can measure movement in any way you like, but if something is not moving in one frame (no change in spatial distance between itself and any other object at rest in that frame) and is moving in another (with a change in spatial distance between other objects which are at rest in that frame), then we have contradictory claims from different frames about whether the object is moving or not, and we can't tell which one is wrong.
If, for the sake of brevity, you don't make that clear in your explanation it wouldn't be so bad if it wasn't for the fact that you build on that omission rather than explaining it.
The fact of it is that you can't tell if you're moving or not in an absolute sense unless you have an absolute frame. That doesn't mean that there isn't an absolute answer known only to that absolute frame. SR ordinarily denies the existence of an absolute frame, but you claim it's open to the idea, and if you're right, the contradictions should force it to accept an absolute frame for some SR models. It doesn't do that though. Why not? Because of a failure to separate out the incompatible and broken models that are being collectively passed off as SR. This is where all your training breaks down, because you've never done this analysis of the different incompatible models in strict isolation from each other. You've never been taken through how they all fail. You have an opportunity to put that right now, but you're trying your best to avoid doing so.
I would have read his words in context, bearing in mind the physics that went before him and the empirical nature of physics. If he simply said "you can't tell if you're moving", since I know that statement, taken in isolation, is demonstrably untrue, I would ask him more about what precisely he means by it.
It is not demonstrably untrue - it is demonstrably true. You cannot tell if you're moving because there's always a frame that says you aren't, and it could be right.
Steve3007 wrote: ↑September 14th, 2018, 2:58 am
A few pages ago, when I asked you some simple questions about it, here:
viewtopic.php?p=318878#p318878
in your answers here:
viewtopic.php?p=318986#p318986
you either didn't answer the questions or answered them wrongly.
I answered them correctly. You just don't like my correct answers because you prefer your incorrect ones which are informed by a broken theory.
This seems odd because they're simple questions. Question 1, for example, could be on a high school Physics exam. But rather than simply giving the obvious answer you started going on irrelevantly about how "the universe supports only one underlying reality".
It's called precision rather than regurgitation of dogma. The answers that you want to hear are the ones based on shackled thinking rather than free rational thought.
This rings alarm bells for me. Maybe you somehow just misunderstood what the question was asking. But I don't see how. I tried to make it as plain and unambiguous as possible. It was a question about how a ball, thrown upwards, moves just after it leaves the hand that throws it.
Your question has a bias built into it that you cannot see because of the way you've been trained. If you say that the ball decelerates, you're assuming a particular frame to be the absolute one, but you don't know it to be the absolute frame, so saying that the ball decelerates is an assumption based on something that may be an error. I'm not going to make a stupid mistake of that kind, but you think I should in order to conform to the stupidity you're pushing. I reject that stupidity. I do not give absolute answers to questions which I can't give absolute answers to without being able to measure the absolute, and the fact that you expect me to do reveals a massive error in your thinking.
So, as I say, maybe we're just talking past each other. But the evidence so far, from your answers to questions like this, suggest to me that you need to brush up on the pre-SR basics. Otherwise the roof that you're constructing will be unsupported by any foundations or walls (to labour that metaphor again).
There is no relevant gap in my understanding. The gap is at your end. You don't rigorously separate out models; you demand absolutes that can't be accessed (and want wrong answers which you can label as correct because they fit with your bias); and you play games where you pretend that SR allows for an absolute frame even though almost everyone in the SR camp rejects one, but also when any acceptance that the speed of light relative to an object may not be what a frame claims it to be automatically leads to an absolute frame not merely being possible, but actively required (in relevant models).
Steve3007 wrote: ↑September 14th, 2018, 3:14 am
Do you accept that an object in free fall in the Earth's gravitational field is accelerating towards the centre of the Earth and can be moving upwards (have its velocity vector pointing upwards), with its speed (the magnitude of its velocity) decreasing?
Yes. If you want to word things that way, I have no problem with that. It doesn't make my way of wording things wrong.
Do you accept that any object moving in a circle, at constant speed, is, by definition, accelerating towards the centre of that circle?
Yes, but I don't let that blind me to the fact that it could also be decelerating in an absolute frame (which is something you want to ban people from realising).
In the context of physics, do you know what kinetic and potential energy are?
Of course.
Steve3007 wrote: ↑September 14th, 2018, 5:49 am
Original question (paraphrased):
1. If I throw a ball upwards, neglecting air resistance, as soon as it has left my hand, is it accelerating, deccelerating or both?
David Cooper wrote:The correct answer is not dependent on the coordinate system you're using, so the answer c is wrong. The correct answer depends on whether it's accelerating, decelerating, or doing one followed by the other, and that depends on its movement relative to the space fabric.
No. the correct answer is by definition that acceleration is the rate of change of velocity with respect to time, which means that it can result in the magnitude of the velocity increasing, reducing or remaining the same. If the magnitude of the velocity remiains the same, but there is still a non-zero acceleration, then the direction of the velocity is changing and the two vectors are perpendicular to each other.
The correct answer is the one I gave you. You asked an absolute question and I answered it on that basis. Your inclusion of the word decelerating also implies that your usage of the word acceleration there excludes cases where something is decelerating. If you want your answer to be the correct one, you need to frame your question with greater care and spell out the definitions of the words you're using in it wherever they go against normal usage. If told you before that the differences between our answers come down to one simple thing - you're asking absolute questions and demanding SR answers (i.e wrong answers) while I'm giving LET answers (i.e. correct ones), and I'm giving you LET answers because SR is broken and should not be given precedence over a rational theory that works.
So an acceleration vector pointing in the opposite direction to a velocity vector means that acceleration is a deceleration, if we define "deceleration" as reduction in speed, which seems reasonable.
This is basic, basic stuff which comes before SR or LET.
It is basic stuff, but if you keep asking absolute questions without realising that that's what you're doing, you're going to keep tripping up. You're mistaking your communication failures for mistakes in my understanding of physics - that is the root of your problem here. Did you ever bother to click through to my reference-frame camera program (from my relativity page)? Anyone who spends a few minutes exploring that should realise that it can only be put together by someone who really knows their stuff. You're searching in the wrong direction. What you should be doing is defining your SR models and showing where they fit in with the ones I've identified. Then we can discuss each one in turn and I'll show you that every single one of them is broken. I can understand that you want to avoid going there, but that is what the invitation here is. If you're sure you have a model that stands up, why delay going straight for the kill. All I ask of anyone is to show me a working model of SR, but by heck it takes a lot of work to drag them towards that, and NONE of them can deliver.
There's nothing "non-genuine" about a non-inertial frame....
There is. In the gravitational case they're fine, but when an object is actually accelerating, a non-inertial frame continually asserts that the speed of light relative to it in all directions is c, and that's a continual contradiction with the previous moment. Such frames are not valid in that they are automatically misrepresentations of reality.
For future reference: Please don't tell me what I'm seeking to do.
You are playing word games, and I will call that out every time you do it.
When I ask a question I am seeking to get from you an answer to that question, as it is stated. Nothing more.
You are applying a bias to them which you don't recognise.
I asked you if you accept the fact that velocity and acceleration are vectors. This is because I am seeking to know whether you appreciate that velocity and acceleration are vectors. If you don't, then it's really difficult to discuss any aspect of physics because we don't speak the same language as each other. I'm just trying to establish whether we speak the same language.
And you're doing this because...? Why are you wasting time on that? It all came out of one little phrase which was transitioning from one idea to another one, momentarily mentioning acceleration and deceleration (but without that contrast being important to the discussion), and moving on to something much more clear cut involving the ticking of two clocks where both are asserted to be ticking faster than the other. So what do you do? You ignore the clocks, and fixate on the acceleration vs. deceleration issue instead. It is actually relevant, but it would be very hard for you to see how given the depth of your indoctrination. You've been taught that something can be accelerating and decelerating at the same time, and it would take a lot of work to deprogram you on that point, which is why I'm not going to bother trying. The ticking rate comparison is much harder to cover up through brainwashing though, because someone who believes that clock A can tick faster than clock B while clock B ticks faster than clock A is manifestly certifiable.
By one very specific definition of the word, yes. It isn't necessarily a real acceleration though just because it's been given a label with a misleading name.
A label with a misleading name?!?!? This, perhaps more than any other answer, appears to me to demonstrate you lack of grasp of basic physics that it is essential to grasp if you're going to tackle more advanced subjects like SR and LET.
That's where you keep repeating the same mistake. You want me to answer absolute questions in a biased way which accepts SR and rejects the absolute frame. I'm not going to let my brain function on such a bias - not for you, and not for anyone. Reason dictates that there must be an absolute frame (in some models) in order to remove the contradictions, and you want me to abandon reason. You want me to parrot mantras from a religious cult instead of doing physics properly. Your cult has given its own definition to a word which I, as someone who is not a member of that cult, refuse to endorse. You are fully entitled to use the word the way your cult uses it and I do not question your understanding of physics on the basis that you do so. I am likewise entitled to use the word my way, and as it's the way that normal people outside of the cult use it, it should not be hard to understand. When you ask absolute questions, I don't apply the unstated bias that you imagine onto it - I answer the actual question that's been asked. The difference between my answers and the ones you want does not reveal a lack of understanding of the physics on my part, but is actively driven by my understanding of the physics and my rejection of your cult. I am in the LET camp, and we have an absolute frame. When we talk about deceleration, we ruddy well mean a deceleration (where kinetic energy is actually being lost rather than gained). Otherwise, we're merely dealing with apparent deceleration.
It is true by definition of the words "acceleration", "velocity" and "circle" that an object moving in a circle has an acceleration vector which points towards the centre of the circle. This a function of the definitions of those words. It's not specific to any individual aspect of physics that we might be discussing. Please tell me that I've misinterpreted you and you understand this bit of basic physics and geometry! If not, as I've said, we have no language in common in which to communicate.
It should be obvious from my answers that I don't accept your definitions as absolute ones. There are alternative ones which are preferable because they are more logical, and you should expect me to use those as standard. Your usage of some words puts a bias into them which allows you to frame things as absolute statements which are logically incorrect by the more rational definitions of the same words and which make precision harder. Your definitions actively warp your ability to understand what you're describing because of their inherent bias.
No it wasn't.
My answer was correct.
Regardless of whether you think there is such a thing as aether, movement is by definition a function of the relationship between objects.
Movement (in the absence of any wording relating what it's relative to) is by definition movement relative to the absolute frame. You're using a biased definition in which the existence of the absolute frame is denied.
If you think there is such a thing as aether then the sentence is rendered meaningful by changing it to: "object A is moving at 5 m/s relative to the aether". And, like any proposition in physics (or science generally) that proposition, to be meaningful, needs to be empirically falsifiable/verifiable, either directly or indirectly. i.e. you need to show how that statement is useful for describing and predicting possible observations.
It is meaningful in physics because not having an absolute frame generates contradictions and invalidates the model. Again though, instead of arguing over linguistics, you should be setting out your SR models and telling me where they fit into my set of models, or where you want to put them if you think they don't fit in my set. Then we can take each one in turn and demolish it.