Philosophy Discussion Forums

Steve3007 wrote: ↑September 30th, 2018, 4:43 am viewtopic.php?p=320659#p320659

David Cooper wrote:This illustrates precisely what's wrong with the way you use the word: "there is no difference between acceleration and deceleration"...

David, please don't casually misquote me. If you think I have said that then find it in my posts and quote the relevant part of the relevant post. Whenever I quote you I do it directly from your posts and try to make the context clear, typically by adding a link to the original post for reference, and/or including the comment to which you were replying.

I apologise for attributing one of Halc's quotes to you, but you did appear to endorse it by quoting it yourself.

It is true by definition that deceleration (reduction in speed) is an instance of acceleration (change in velocity),

by one definition, and it is false by another definition - there are at least two words here with the same form but with different definitions. This is common in language, and when it happens, each is a word in its own right, none of them overriding the others that share the same form.

And you can't keep using this "man in the street" defense for your inaccuracies, because when you say this...

You may be capable of imagining an acceleration to be a deceleration at the same time, even though it can't really be

...shortly after the comment of mine that you misquoted, you make it clear that you still haven't got your head around the above simple definitions. I think "the man in the street" would have no trouble with them. So, as a student of advanced physics and an expert in language, why do you?

The point is, you're attacking me for using a word in a fully legitimate way while you want me to use the word in a different legitimate way - they aren't really the same word. In my AGI system, they have completely separate entries. However, whenever you use a word of this kind in speech, you don't supply the hidden ID which ties it to a specific definition - you use it ambiguously as a result, and so do I, if we ignore the places where we've both explained how we're using them, but it would be better if we didn't ignore those explanations because then we can simply understand the words the way they're intended. When you ask an absolute question, I give an absolute answer using the word I choose to use, but I also make it clear which definition I'm using by explaining that my usage of the word there does not allow it to represent a deceleration (where kinetic energy is being lost). The problem here is that you want to force your usage of words on me, banning me from using perfectly valid alternative definitions in favour of others that carry an SR bias, but I'm not going to give absolute answers to absolute questions using words with an SR bias because that automatically misleads people.

Tamminen wrote: ↑September 30th, 2018, 8:38 amAnd during this brief time in T clock 15 years have elapsed in D clock seen from T. Simultaneity is a strange thing. But this is the solution for the paradox. There is no contradiction. The "underlying reality" is there: the D clock ticks for 20 years and the T clock ticks for 10 years. But the part of this period of 20 years in D clock that is simultaneous with a given part of the 10 years in T clock as seen from T's perspective depends on the current frame and the changing of frame by accelerating. I think the case is closed. Except perhaps not for everyone.

Simultaneity is not a strange thing. If you're using a set zero model, time doesn't run - there is no such thing as simultaneous because there is no time in the model at all. All it has is a "time" dimension.

If you're using a set 1 model, time does run, but no clocks run slow. Because they don't run slow, you get event-meshing failures during the construction phase as you build a block, but once the block is complete, you still get mismatches in how quickly parts of each strand move through the block. If you feed the content in like long strings and mark them once every metre along them, you'll find that some of those marks move through the block more quickly than others, and a mark on one strand which enters the block at the same time as its neighbour may at some point re-encounter the same strand and find that the mark it meets up with is a billion km behind the one it was next to before. This is a strange model, but these consequences are inherent to any model that has running time with no clocks running slow. It does not happen in set zero models, but people often mix models and assert aspects of set 1 models to set zero models, even though the two sets are incompatible - they are breaking the rules of mathematics by doing so.

If you're using a set 2 or 3 model, then you have running time and you have some clocks ticking faster than others. In set 2 models you have two clocks both ticking faster than each other at the same time, thereby invalidating the model. In set 3, that problem is avoided by having an absolute frame.

If you keep mixing different models, you can come to incorrect conclusions, and that is what most SR people do. There is no paradox - each model resolves the problem in a different way, but in the case of set 2 models, that is done by recognising that the model is broken. The fact that other models resolve the "paradox" in other ways does not restore set 2 models - they remain broken.

David, first I'll try once again to nail this problem you have with the standard usage of words:

viewtopic.php?p=320693#p320693

David Cooper wrote:What I said remains true: it is the way people naturally think until the SR people start messing with their minds. That doesn't preclude other physicists from using words in unnatural ways before SR came along.

What you said was "That is the way people naturally think, until the SR people start messing with their minds.". I've pointed out many times that Newton's mind had not been "messed with" by Einstein. Neither have the minds of all the school children who learn Newtonian mechanics. You just ignore it. You seem incapable of simply admitting that what you said was not true and that it's easy to explain the definition of the term "acceleration", in the context of physics, without it having anything whatever to do with Special/General Relativity. As I've said, this simply shows your strange obsession with those particular theories of physics, and the bizarre idea that all other theories, including those that came hundreds of years before them, are tainted by them.

Now you've resorted to saying that the definition of "acceleration", in the context of physics, is somehow "unnatural". What on Earth does that mean!? What other standard words are you going to suddenly declare to be "unnatural"? How can we have any meaningful conversation if whenever I use a word in its standard sense you might simply declare that sense to be "unnatural"?

viewtopic.php?p=320694#p320694
To Halc:

It is ambiguous when used as an answer to an absolute question - if you say something accelerates in that context, you imply that it is accelerating relative to space and reducing the relative speed at which light races away ahead of it. I always have that in mind when absolute questions are asked. SR people don't. That is the difference, and it's the SR people who are getting it wrong.

No you don't imply that. Newton and Gallileo were not "SR people".

viewtopic.php?p=320698#p320698

I apologise for attributing one of Halc's quotes to you, but you did appear to endorse it by quoting it yourself.

Please quote me doing this. As I've said, if you tell me that I've said something, please make it clear where I said it, just so that we all know what we're referring to.

by one definition, and it is false by another definition - there are at least two words here with the same form but with different definitions. This is common in language, and when it happens, each is a word in its own right, none of them overriding the others that share the same form.

But we are discussing physics, are we not? In that context I use the standard definitions of words. Likewise, we both use the word "frame", for example, as it's used in the context of physics. (Not just SR. Physics). If we were discussing art then we might be referring to a rectangular piece of wood that goes around a picture. But we're not. We're discussing physics. Aren't we?

The point is, you're attacking me for using a word in a fully legitimate way while you want me to use the word in a different legitimate way - they aren't really the same word.

No, I'm objecting to you doing the following things:

1. Incorrectly stating that the standard definition of "acceleration" has anything specifically to do with SR.

2. Incorrectly saying such things as "You may be capable of imagining an acceleration to be a deceleration at the same time, even though it can't really be.", when, as we know, it was true long before SR that deceleration is a specific type of acceleration and the question of whether an object is deemed to be accelerating or decelerating is dependent on the reference frame from which its movement is measured. This is true whether or not you believe that one particular reference frame is the absolute one in which the ether is stationary.

3. Incorrectly saying that there is anything ambiguous about the word "acceleration" when used according to its standard definition. It is unambiguous regardless of whether you think that one particular reference frame is the absolute one.

When you ask an absolute question, I give an absolute answer using the word I choose to use, but I also make it clear which definition I'm using by explaining that my usage of the word there does not allow it to represent a deceleration (where kinetic energy is being lost)

An object's kinetic energy is dependent on the magnitude of the object's velocity (a.k.a. its speed). Classically, K.E. = ¹/₂mv². So if I am sitting in a moving car, my K.E. with respect to that car is zero because my velocity with respect to that car is zero. My K.E. with respect to the road is non-zero. If I am lying in the road the opposite is true. If I jump out of a moving car, I rapidly increase my speed relative to the car and decrease my speed relative to the road. Therefore the same is true of my K.E. relative to those two reference frames. If you believe that there is an absolute reference frame then I also have a velocity and a K.E. relative to that reference frame. It has no bearing on what I've said here.

The problem here is that you want to force your usage of words on me, banning me from using perfectly valid alternative definitions in favour of others that carry an SR bias, but I'm not going to give absolute answers to absolute questions using words with an SR bias because that automatically misleads people.

No, I am trying to get you to realize that the standard definitions of words, such as "acceleration", in physics are not tied to one particular theory, like SR. And you can't get out of that by simply declaring the definitions you personally, for some reason, dislike are somehow "unnatural". These are the perils of trying to critique one particular relatively advanced topic in physics without doing the groundwork, as I said a long time ago.

But when I have pointed all of this out to you, you simply ignore it and just declare yourself to be telling the truth at all times.

OK, now onto the parts of the posts that were more specific to SR and not just about the definitions of words.

Another reminder of the 3 experiments that we were considering:

1. You stand still throughout. I move away from you and then turn around and come back. At speeds v and -v relative to the Earth frame and you.

2. You move at speed v relative to the Earth frame throughout. I move at speed 2v, then I stop and wait for you to catch up.

3. You move at speed v relative to the Earth frame throughout. I stand still for a while then start moving and catch you up by travelling at speed 2v, relative to the Earth frame.


viewtopic.php?p=320694#p320694
To Halc:

David Cooper wrote:It [acceleration] is ambiguous when used as an answer to an absolute question - if you say something accelerates in that context, you imply that it is accelerating relative to space and reducing the relative speed at which light races away ahead of it. I always have that in mind when absolute questions are asked. SR people don't. That is the difference, and it's the SR people who are getting it wrong.

If you say that something is increasing its speed with respect to a particular reference frame which you regard as the absolute one then there is no ambiguity. It is also decreasing its speed with respect to some other reference frames.

viewtopic.php?p=320695#p320695

I wasn't thinking in terms of an Earth frame - we want to eliminate the rotation, so the experiments need to be done in deep space as a space walk.

To clarify:

I was referring to Earth simply as another non-inertial reference frame. From your words, I took it as a given that we are neglecting the effects of the Earth's mass and rotation. If we prefer, we can instead imagine some kind of starting line, of negligible mass, far away from any massive bodies, that is stationary in a non-inertial reference frame. When I've said "Earth" please take this as shorthand for that starting line. Sorry for any confusion. Obviously I'm not going to refer to that starting line reference frame simply as "space" because the concept of measuring my position and velocity "relative to space" is not physics. It's not a measurement that could be made. It is not empirical.

Throughout the first experiment, I'm at rest in the frame being used. In the other two experiments, I'm moving relative to that frame.

Agreed. In the second two experiments you are at rest relative to a frame which is moving at speed v relative to the starting-line frame.

In the third experiment, you are at rest in that frame during the first leg. Clock 3 is at rest in that frame at all times. Clock 4 is moving at v through the frame at all times.

Agreed.

Reply to: "i.e. it's a mirror image of the first two. I presume you agree with this?"

It looks like one if you change frame to look at each experiment,...

All three experiments are identical from the point of view of different inertial reference frames. The Principle of Relativity observes the fact that the laws of physics are the same in any inertial reference frame. Therefore all 3 experiments are identical.

...but if you do that, you're changing the speed of light relative to clocks 3 and 4.

No you're not. The speed of light is observed to be the same when measured against any inertial reference frame. Clocks 3 and 4 are both stationary in inertial reference frames. Observers who are travelling with clocks 3 and 4 will measure the speed of light in a vacuum to be c, regardless of the movements of any other objects that might happen to be around, such as you and me.

I put in the bit about other people moving clocks and staying in inertial frames for the sake of other readers who might think the accelerations have a magic roll.

I don't think anybody will think that acceleration has a "magic role". What they might do is explain the "twin paradox" in the context of General Relativity, with its equivalence principle between acceleration and gravity. But, as we know, it's not necessary to invoke General Relativity to accurately describe the "twin paradox". It can be accurately described, with no contradictions, using only Special Relativity, as Halc and Tamminen have been doing. One of the ways in which it can be described (but not the only way) is to point out that when the travelling twin turns around and comes back he switches inertial reference frames.

The speed of light relative to clocks 3 and 4 reveals an asymmetry if clock 3 is ticking faster than clock 4 (or the reverse).

No it doesn't. The speed of light as measured by observers travelling with clocks 3 and 4 is c. The rate at which clocks 3 or 4 are observed to be ticking depends on the clock against which they are compared and the relative velocities of the clocks. If we're talking about clocks 3 and 4 measuring their tick rates relative to each other, by sending signals between them, then they will each measure the other to be ticking more slowly than themselves. Those two clocks will never meet again, so that is the only way that they will ever measure their relative tick rates. If you're talking about measuring the tick rate of clock 3 relative to another clock, or clock 4 relative to another clock, then specify which other clock you're referring to.

I'll leave it there for now and carry on where I left off later.

Before I continue I'll just say that I agree that when I mentioned the speed of "2v" I should strictly speaking have said "xv" where x is greater than 1 and less than 2, and where if the relative speeds between pairs of objects are low compared to the speed of light it is very close to 2. This doesn't affect the argument, but I should have made it clear.

OK, carrying on where I left off in my previous post:

viewtopic.php?p=320716#p320716

which deals with the points in this post of David's:

viewtopic.php?p=320695#p320695

David Cooper wrote:Except that they aren't physically identical - that's where you're making your error. They only look identical if you change the speed of light relative to the arena in which we're carrying out the experiments, but that's cheating.

No, the fact that they're physically identical has nothing, in itself, to do with the speed of light. They are physically identical because each can be transformed into the other by viewing from a different inertial reference frame. And the laws of physics are the same in all inertial reference frames. The error that you appear to be making is in failing to remember that the concept of speed, including the concept of the speed of light, is only meaningful when expressed in terms of how it is measured. This is true of all concepts in physics.

The speed of light, as measured against each reference frame is always c. You can add in as many other clocks as you like, and have them move around in any way that you like. They will be of no concern to us when we make measurements of the relative tick rates of our two clocks. If we wish to make measurements of relative tick rates between other clocks, such as clocks 3 and 4, or between those other clocks and our own clocks, then we have to specify, in each case, which two clocks we are comparing and how they are moving relative to each other.

A rotating Earth would interfere with the experiments, so we're doing this in deep space. The arena in which we're doing the experiments has clock 3 at rest in it throughout.

Yes, understood. Clock 3 is at rest relative to the starting line.

No - it's where you start to fudge things. If set it out with absolute clarity and precision.

I understand now that clock 4 moves at speed v relative to the starting line througout all 3 experiments. I did not get that on first reading. Apologies for the confusion.

Which part of "Throughout the first leg of the third experiment, that fourth clock and I were co-moving" is not correct? How could it be accompanying you in the first leg of experiments 2 and 3 when it kept going in experiment 1 when you turned back? You aren't reading carefully.

As I said, all confusion about the movement of clock 4 resolved now.

It's absolutely clear what I'm saying about the 4th clock.

Yes, it is clear to me now.

It keeps on moving at v relative to clock 3 throughout the three experiments.

Yes.

The fourth clock moves with you on the first leg of the first experiment. It keeps going, but you turn back.

Got it.

It proves exactly what I said it proves. If my clock was ticking faster than yours during the first leg of the first experiment, then your clock was ticking faster than mine during the first leg of the third experiment. This is (for rational people) an undeniable conditional truth.

As I've said, measurements of the rate at which a clock ticks are only physically meaningful if you specify the other clock against which you are measuring it and the relative motions of those two clocks.

Let's call yours clock 1 and mine clock 2.

During the first leg of all 3 of the experiments, we are receding from each other at relative speed v. Therefore, if our respective clocks send signals to each other we will each see those signals as slower relative to the ticks of our own clocks. This is true regardless of what any other clocks might be doing..

In the 1st leg of expt 1, clocks 1 and 2 are receding from each other at speed v. Clock 1 is stationary relative to clock 3. Clock 2 likewise with clock 4.

In the 1st leg of expt 3, clocks 1 and 2 are receding from each other at speed v. Clock 1 is stationary relative to clock 4. Clock 2 likewise with clock 3.

So clocks 1 and 2 will measure each other's relative tick rates exactly the same in leg 1 of expts 1 and 3. As they send clock tick signals between each other they will each see those received tick signals as slower than their own ticks, because the only relavant factor here is the relative speed of clocks 1 and 2.

But you introduced clocks 3 and 4 and stipulated that they stay in the same respective reference frames, relative to the start-flag frame, in all 3 experiments. Therefore their movements relative to clocks 1 and 2 vary between those experiments. If we view each experiment from a reference frame in which clock 1 is stationary and the initial movement of clock 2, relative to clock 1, is to the right, then clocks 3 and 4 are moving differently, relative to clocks 1 and 2, in each experiment. They swap roles.

Do you see how this works?

In the 1st leg of expt 1, clocks 1 and 4 will see the ticks from each other's clocks coming in slower than their own. Clocks 2 and 3 will also see the ticks from each other's clocks coming in slower than their own.

In the 1st leg of expt 3, clocks 1 and 3 will see the ticks from each other's clocks coming in slower than their own. Clocks 2 and 4 will also see the ticks from each other's clocks coming in slower than their own.

So, you see, by adding clocks 3 and 4, and reflecting left-right the reference frame in which expts 1 and 3 are identical (but not doing that with clocks 3 and 4), you simply reverse the roles of clocks 3 and 4 between these two experiments. But you don't reverse the roles of clocks 1 and 2 with respect to each other.

To get your head around this you have to think carefully about the relative movements of these clocks, in these 3 experiments, relative to various different inertial reference frames. It helps if you can mentally picture that, including mentally flipping the experiment left-right; imagining yourself going around the back, as it were.

I've been fully clear about what's doing what, and I've told you exactly what clocks 3 and 4 reveal. You're just taking a long time to get your head around this kind of thinking, but it's something you need to get on top of if you want to test SR properly. What I'm doing is stopping you changing the speed of light relative to the arena between experiments. Clock 3 ticks at a constant rate throughout, and clock 4 ticks at a different constant rate throughout. In experiment 1, my clock ticks at the same rate as clock 3, and in experiment 3 my clock ticks at the same rate as clock 4. In leg one of the first experiment, your clock ticks at the same rate as clock 4, and in the first leg of experiment 3 your clock ticks at the same rate as clock 3. Every competent mathematician in the world will agree with this, and they'll also agree that if my clock was ticking faster than yours during the first leg of the first experiment, then your clock was ticking faster than mine during the first leg of the third experiment.

No, what they'll agree is what I explained above - that when you say such things as "Clock 3 ticks at a constant rate throughout" and "clock 4 ticks at a different constant rate throughout" you have to specify which other clock you're measuring them against and the reference frame against which you're making those measurements.

As I explained above, in clocks 3 and 4, you have added 2 new clock which serve opposite purposes in experiments 1 and 3.

It was ticking at the same rate as my clock during the whole of the first experiment, and it was ticking at the same rate as yours throughout the first leg of the third experiment.

Yes, clocks 3 and 4 swapped roles because, as measured against the respective reference frames in which expts 1 and 3 are identical, they swapped movements.

I've checked it again to make sure my wording was right, and it was. Clock 3 is always stationary relative to the arena in which we're doing the experiments - we never accelerate it. Clock 4 moved at v relative to clock 3 at all times - we never accelerate it either.

That's right. Clocks 3 and 4 never accelerate. They remain in their respective inertial reference frames. But, as I said, they swap roles between expts 1 and 3.

They show a lot. If clock 3 is ticking faster than clock 4 during the first experiment, it is ticking faster than clock 4 during all three experiments...

In all 3 expts, clocks 3 and 4 are receding from each other at speed v. So in all 3 expts, they each see tick signals from the other coming in slower than their own ticks.

...My clock is ticking at the same rate as clock 3 during the first experiment and your clock is ticking at the same rate as clock 4 during the first leg of the first experiment. Your clock is ticking at the same rate as clock 3 during the first leg of the third experiment and my clock is ticking at the same rate as clock 4 throughout the third experiment. How much clearer than that do I need to spell it out?

Absolutely. As I said, and as you have demonstrated perfectly here, clock 3 and 4 swap roles between expts, from the point of view of the reference frames in which the expts are the same.

It is at rest in the arena where we're doing the experiments throughout - it is ticking at a constant rate because it never accelerates.

A constant rate relative to what?

I've been absolutely clear. You just need to load the experiments into your head more carefully and then process them with equal care.

It is my view that you need to better get your head around the process of viewing various moving objects from the point of view of different inertial reference frames.

The way to tell if a clock is ticking at a constant rate is to see if it's being accelerated.

In the absence of acceleration, the way to measure the rate at which a clock ticks is to compare it with another clock.

We do the experiment in deep space with more or less equal amounts of distant matter in all directions sitting in galaxies, so any tiny acceleration force that might be acting on the arena is too small to make any significant change to the ticking rates of clocks sitting in or moving through the arena at constant speed (relative to it).

Understood. We're assuming that the starting-flag frame is inertial and that there are no gravitational forces at work.

David, I've been thinking a bit more how this could be demonstrated to you. An animation would be good. But, failing that, I'd suggest you draw diagrams on a piece of paper of the 3 experiments and the 4 clocks, try to imagine their relative movements, and then try to imagine taking experiment 3, flipping the paper over so that you've looking at it from the back and then moving the whole piece of paper sideways at speed v. Then observe the fact that clocks 1 and 2, from your vantage point, are moving in exactly the same way as they did in experiment 1 but clocks 3 and 4 have swapped roles.

I guess tracing paper would be good for this.

Typo:

In this post:
viewtopic.php?p=320716#p320716

where it says "I was referring to Earth simply as another non-inertial reference frame." it should have said "I was referring to Earth simply as another inertial reference frame.". I try to proof read my posts but this slipped past. (It is annoying that posts can no longer be edited after posting.)

David Cooper wrote: ↑September 30th, 2018, 5:53 pm In set 2 models you have two clocks both ticking faster than each other at the same time, thereby invalidating the model.

At the same time? If the clock in frame A ticks for 4 seconds and the clock in frame B ticks for 2 seconds, simultaneously for an observer in frame A, this means that the clock in frame B ticks more slowly than the clock in frame A for the observer in frame A. Now for an observer in frame B those same 2 seconds ticking in the clock in frame B are not simultaneous with the 4 seconds in the clock in frame A, being simultaneous with only 1 second in the clock in frame A, and this means that the clock in frame A ticks more slowly than the clock in frame B for the observer in frame B. However, the 4 seconds and the 1 second in the clock in frame A are not simultaneous for either of the observers. So simultaneity is not symmetric, and therefore we cannot say that those two clocks both tick faster than the other at the same time. No contradiction.

Tamminen wrote:...and therefore we cannot say that those two clocks both tick faster than the other at the same time. No contradiction.

Yes, as you've suggested, we can ask: At the same time as measured by what clock? Because we know that time is a thing that is measured by clocks, so simply saying "at the same time" without mentioning a clock is, strictly speaking, meaningless.

And we can answer (as you have): As measured by clock A, clock A ticks faster. As measured by clock B, clock B ticks faster.

A little bit more description of the 3 experiments, which each consist of two legs. Just to make the point again.

Let SL = The starting-line reference frame (with a starting line object at rest relative to it).
Let C1 = Clock 1.
Let C2 = Clock 2.
Let C3 = Clock 3.
Let C4 = Clock 4.
Let the positive direction for speed be to the right, and the negative direction to the left.


Experiment 1.
C1 stands still relative to SL throughout.
C2 moves at speed v relative to C1 during leg 1 and then at speed -v relative to C1 during leg 2.
C3 stands still relative to C1 throughout.
C4 moves at speed v relative to C1 throughout.

Experiment 2.
C1 moves at speed v relative to SL throughout.
C2 moves at speed v relative to C1 during leg 1, then at speed -v relative to C1 during leg 2.
C3 moves at speed -v relative to C1 throughout.
C4 stands still relative to C1 throughout.

Experiment 3.
C1 moves at speed v relative to SL throughout.
C2 moves at speed -v relative to C1 during leg 1, then at speed v relative to C1 during leg 2.
C3 moves at speed -v relative to C1 throughout.
C4 stands still relative to C1 throughout.


Note the relative speeds of C1, C2, C3 and C4. Note the fact that experiments 1 and 3 are the same except that they are mirror images of each other and C3 and C4 switch roles. So if we peel the labels off C3 and C4 and swap them, experiments 1 and 3 are the same. The labels don't affect the results of the experiments. Swapping the direction that we regard as being the positive one does not affect the results.

This post is dedicated to the diversion (which people who aren't obsessed with irrelevance needn't bother reading about):-

Steve3007 wrote: ↑October 1st, 2018, 1:30 am What you said was "That is the way people naturally think, until the SR people start messing with their minds.". I've pointed out many times that Newton's mind had not been "messed with" by Einstein.

I'm not interested in historical cases - today it's the SR lot that messes with people's minds, brainwashing them against the best explanation of reality.

Now you've resorted to saying that the definition of "acceleration", in the context of physics, is somehow "unnatural". What on Earth does that mean!? What other standard words are you going to suddenly declare to be "unnatural"? How can we have any meaningful conversation if whenever I use a word in its standard sense you might simply declare that sense to be "unnatural"?

I'm not banning you from using words in unnatural ways. I'm simply refusing to use words in unnatural ways myself where in places where they are misleading.

Newton and Gallileo were not "SR people".

Newton and Gallileo would have understood my usage.

Please quote me doing this. As I've said, if you tell me that I've said something, please make it clear where I said it, just so that we all know what we're referring to.

It was your post of September 29th, 2018, 1:08 pm. I quoted the relevant chunk in the reply that you objected to (second post on page 14, if the forum software cuts threads into sections the same way for you).

But we are discussing physics, are we not? In that context I use the standard definitions of words.

And when we're discussing physics with different models in mind, different usage of vocabulary can be necessary, as in this case.

No, I'm objecting to you doing the following things:

1. Incorrectly stating that the standard definition of "acceleration" has anything specifically to do with SR.

It fits with SR, but it doesn't fit properly when giving absolute answers to absolute questions where the absolute answers don't fit with SR.

2. Incorrectly saying such things as "You may be capable of imagining an acceleration to be a deceleration at the same time, even though it can't really be.", when, as we know, it was true long before SR that deceleration is a specific type of acceleration and the question of whether an object is deemed to be accelerating or decelerating is dependent on the reference frame from which its movement is measured. This is true whether or not you believe that one particular reference frame is the absolute one in which the ether is stationary.

It's plain bad physics to call a deceleration an acceleration if you have an absolute frame in mind.

3. Incorrectly saying that there is anything ambiguous about the word "acceleration" when used according to its standard definition. It is unambiguous regardless of whether you think that one particular reference frame is the absolute one.

It is ambiguous - it requires multiple definitions.

An object's kinetic energy is dependent on the magnitude of the object's velocity (a.k.a. its speed). Classically, K.E. = ¹/₂mv². So if I am sitting in a moving car, my K.E. with respect to that car is zero because my velocity with respect to that car is zero. My K.E. with respect to the road is non-zero. If I am lying in the road the opposite is true. If I jump out of a moving car, I rapidly increase my speed relative to the car and decrease my speed relative to the road. Therefore the same is true of my K.E. relative to those two reference frames. If you believe that there is an absolute reference frame then I also have a velocity and a K.E. relative to that reference frame. It has no bearing on what I've said here.

In one case, it's counterfactual because you're losing energy in some cases where you claim you're gaining it. Sloppy use of language leads to sloppy thinking, and that's why physics is so stuck in this SR mess. That sloppy use of language brainwashes people, and it doesn't matter how much authority that sloppy usage carries. It misleads people. The way to shake people out of that error is to use the words the way I do in relevant contexts.

No, I am trying to get you to realize that the standard definitions of words, such as "acceleration", in physics are not tied to one particular theory, like SR. And you can't get out of that by simply declaring the definitions you personally, for some reason, dislike are somehow "unnatural". These are the perils of trying to critique one particular relatively advanced topic in physics without doing the groundwork, as I said a long time ago.

Your preferred definition blinds people to the underlying reality. I want to draw people's attention to the underlying reality. You are making an illegal move (illegal in logic) by trying to stamp on my use of these words.

But when I have pointed all of this out to you, you simply ignore it and just declare yourself to be telling the truth at all times.

I ignore it because I reject all false authorities. (And this is a time-wasting diversion which has nothing to do with my argument against SR.)

It was your post of September 29th, 2018, 1:08 pm. I quoted the relevant chunk in the reply that you objected to (second post on page 14, if the forum software cuts threads into sections the same way for you).

You can directly reference a post by copying the URL and pasting it into an open-square-brackets url close-square-brackets tag. To get the URL of a post, click on the little icon at the top left of the post, immediately to the left of the "by ..." line.

Your preferred definition blinds people to the underlying reality. I want to draw people's attention to the underlying reality. You are making an illegal move (illegal in logic) by trying to stamp on my use of these words.

OK. You win. Use words however you want. But I won't guarantee that I can understand you.

Do you think apple is fish brain?

Steve3007 wrote: ↑October 1st, 2018, 2:43 amWhen I've said "Earth" please take this as shorthand for that starting line.

That's fine - I'm happy with shorthand of this kind where the transformation rules have been explained.

All three experiments are identical from the point of view of different inertial reference frames. The Principle of Relativity observes the fact that the laws of physics are the same in any inertial reference frame. Therefore all 3 experiments are identical.

That is where you're making your fundamental mistake. All three experiments appear identical, but they aren't. If you're using a set zero model, time doesn't run (or indeed exist at all), so there's no direct problem there, but when we're exploring the contradictions we're concerned with specific models which have running time where we allow some clocks to run faster than others rather than having them all run at the same rate as each other at all times (which would take us into the models with event-meshing failures), we are specifically testing set 2 and set 3 models, and what we find here allows us to eliminate the set 2 ones (including Einstein's original SR).

...but if you do that, you're changing the speed of light relative to clocks 3 and 4.

No you're not.

Yes you are. Every time you change frame, you change the speed of light relative to the arena.

The speed of light is observed to be the same when measured against any inertial reference frame. Clocks 3 and 4 are both stationary in inertial reference frames. Observers who are travelling with clocks 3 and 4 will measure the speed of light in a vacuum to be c, regardless of the movements of any other objects that might happen to be around, such as you and me.

This is the big result of the brainwashing - it is very effective in shutting down people's rational thinking, and you're one of an army of such victims. I've set a simple proof in front of you here, but you appear to be unable to process it. In experiment 1:-

If my clock is ticking faster than yours during leg 1 of your trip, then clock 3 is ticking faster than clock 4. In experiment 3.

If my clock is ticking faster than yours during leg 1 of your trip, then clock 4 is ticking faster than clock 3.

If both of these experiments are identical, then clock 3 is ticking faster than clock 4 and clock 4 is ticking faster than clock 3, but that's a mathematical impossibility.

The reality is that if my clock is ticking faster than yours during leg 1 of your trip in the first experiment, then your clock is ticking faster than mine during leg 1 of your trip in the third experiment.

When it comes to logical reasoning, you seem to have an entire module missing. You're not alone in that though, because it is very much the norm for people who imagine that SR is valid. Some of them do see the problem though (Minkowski, perhaps) and recognise that set 2 models don't work.

One of the ways in which it can be described (but not the only way) is to point out that when the travelling twin turns around and comes back he switches inertial reference frames.

And that means changing the speed of light relative to the system for each leg, leading to a complete misunderstanding of what's going on.

The speed of light relative to clocks 3 and 4 reveals an asymmetry if clock 3 is ticking faster than clock 4 (or the reverse).

No it doesn't.

Yes it does - you are changing frame and thereby changing the speed of light relative to the system. You're doing bad physics.

The speed of light as measured by observers travelling with clocks 3 and 4 is c.

The apparent speed of light relative to them in each case is c. The actual speed of light relative to them may be different for each.

The rate at which clocks 3 or 4 are observed to be ticking depends on the clock against which they are compared and the relative velocities of the clocks.

We're only interested in how fast they're ticking relative to each other. You've playing a game where clock 3 is ticking more quickly than clock 4, then you change frame and claim that clock 4 is ticking more quickly than clock 3, but you're trying to have your cake and eat it by taking both of these things to be true at the same time.

If we're talking about clocks 3 and 4 measuring their tick rates relative to each other, by sending signals between them, then they will each measure the other to be ticking more slowly than themselves. Those two clocks will never meet again, so that is the only way that they will ever measure their relative tick rates. If you're talking about measuring the tick rate of clock 3 relative to another clock, or clock 4 relative to another clock, then specify which other clock you're referring to.

We only need to compare them against each other, but we can include other clocks in that process. In experiment 3, I start next to clock 3 and move away from it at the same speed as clock 4, so my clock ticks at the same rate as clock 4.

You're playing an irrational game where you change the speed of light relative to the system in order to pretend that experiments 1 and 3 are the same, but they aren't the same. There's an asymmetry there which you're simply ignoring and pretending doesn't exist. This shows that you have bought into the dogma 100%, because it's controlling you - you appear to be incapable of thinking independently of it any more.

Let's lock things down more clearly by doing experiments 1 and 3 at the same time with the help of a couple of friends. We are at rest in a frame in deep space which I call the arena. I'm going to stay in the same place in the arena throughout, so my clock will tick along with clock 3 throughout. Einstein is going to move away from me at v, so he will accompany clock 4 throughout. You are going to stay with me for a while, then you'll race after Einstein to catch up with him, so your clock will tick at the same rate as mine for the first leg of your trip, and then tick at a different rate during the second leg. Lorentz will initially travel with Einstein but then he'll turn round and come back to me. So Lorentz and I are doing experiment 1 while you and Albert are doing experiment 3.

Lorentz's clock runs more slowly than mine over the whole trip, so we can speculate about how that happened. There are five rational possibilities for this when we're testing set 2 and 3 models, as I set out earlier. Those options are:-

(A) My clock ticked more quickly than Lorentz's clock on both legs of his trip.
(B) My clock ticked more quickly than Lorentz's on the first leg and his ticked at the same rate as mine on the second leg.
(C) My clock ticked at the same rate as Lorentz's on the first leg and more quickly than his on the second leg.
(D) My clock ticked more quickly than Lorentz's on the first leg and more slowly than his on the second leg.
(E) My clock ticked more slowly than Lorentz's on the first leg and more quickly than his on the second leg.

Options (B), (C), (D) and (E) recognise the possibility that the frame in which the arena's at rest is not the absolute frame, but if you deny the existence of an absolute frame, then you can assume that (A) must be correct, so you can ignore the other options if you wish. In the same way, there are five possibilities for what happened with your clock and Einstein's, so we can set them out and give them names in the same way:-

(F) Einstein's clock ticked more quickly than yours on both legs of your trip.
(G) Einstein's clock ticked more quickly than yours on the first leg and at the same rate as yours on the second leg.
(H) Einstein's clock ticked at the same rate as yours on the first leg and more quickly than yours on the second leg.
(I) Einstein's clock ticked more quickly than yours on the first leg and more slowly than yours on the second leg.
(J) Einstein's clock ticked more slowly than yours on the first leg and more quickly than yours on the second leg.

There's some symmetry about this, but it isn't complete. Whenever we do this in the same arena, and all the more obviously when we do this at the same time in the same arena, we should be able to see the nonsense that comes out of changing frame in between the experiments to change the speed of light relative to the arena. Einstein's and Lorentz's clocks were ticking at the same rate as each other during the first leg, and my clock and yours were ticking at the same rate as each other during the first leg too. Logic dictates the following asymmetric things:-

If (A) --> not (F), not (G), not (H), not (I).
Therefore if (A) --> (J).

If (B) --> not (F), not (G), not (H), not (I).
Therefore if (B) --> (J).

If (C) --> not (F), not (G), not (I), not (J).
Therefore if (C) --> (H).

if (D) --> not (F), not (G), not (H), not (I).
Therefore if (D) --> (J).

If (E) --> not (H), not (J).
Therefore if (E) --> (F) or (G) or (I).

These rules come from LET, but they have relevance to set 2 models too. Set 2 models simply don't care and ride the contradictions, but no one who pushes a set 2 model should be denying that it generates contradictions. The contradictions are clear. If my clock is ticking more quickly than Lorentz's during the first leg and Einstein's clock is ticking more quickly than yours during the first leg, then my clock is ticking more quickly than yours while they're co-moving (and side by side), and Einstein's is ticking more quickly than Lorentz's while they're co-moving (and side by side). This renders set 2 models magical, ruling them out from real physics.

Those who can't recognise the contradictions here clearly doesn't have an adequate grasp of relativity, so they need to sort themselves out.

I messed up part of that in an edit aimed at laying it out better - it had been a single paragraph. Here it is chopped up correctly:-

In experiment 1, if my clock is ticking faster than yours during leg 1 of your trip, then clock 3 is ticking faster than clock 4.

In experiment 3, if my clock is ticking faster than yours during leg 1 of your trip, then clock 4 is ticking faster than clock 3.

If both of these experiments are identical, then clock 3 is ticking faster than clock 4 and clock 4 is ticking faster than clock 3, but that's a mathematical impossibility.

The reality is that if my clock is ticking faster than yours during leg 1 of your trip in the first experiment, then your clock is ticking faster than mine during leg 1 of your trip in the third experiment.