# Relativity and simple algebra II

ZZZZZZZZ bed time.

Experiments show that time dilation and length contraction must be real effects.
in order for SR's explanation to be correct. This is a purely circular argument. The results bear out the hypothesis, therefore the hypothesis must have been correct all along and let's make sure of that by using the hypothesis for 116 years as if it's a genuine conclusion that now becomes fact. I can solve every example of relativity without once invoking length contraction. There is no physical experiment that has been performed to verify its existence. It even vanishes like a phantom effect once the velocity that creates it disappears. Yet age difference from the twin paradox persists as a measurable result even after the velocity is gone. How come one is persistently real and measurable and the other is not and yet you still insist it is. Length contraction is the result of conflicting perspectives of simultaneity. Perspectives are illusions just like mirages yet you say there must be water there because you can see it and there is no other possible explanation and if there is you don't want to accept it.

This is a response to post #155.

James R said:
It sounds like you don't believe that length contraction is a real effect, even though you accept time dilation. Is that a correct summary of your views?
No. You tell me what I said.
Okay. We're going to keep playing a guessing game, are we, rather than you telling me what you believe?

Here's my next guess: do you believe that neither length contraction nor time dilation are real effects? Is that correct?

If not, there are two more possibilities that we will have to explore in order to find out what you believe, presumably. It would be quicker if you just told me, but we can play the guessing game if you want.

James R said:
Do you agree with me that, if she laid out one of her own metre rulers next to Bob's (as she watches Bob's one fly past), she'd measure two different lengths for the two rules, even though the rulers would be identical if brought to rest with respect to one another?
ralfcis said:
No, that's what the philosophy of SR believes.
Okay. Let's get to the bottom of it this way:

If Bob observes coordinates (x,t) for a particular spacetime event, and Alice observes coordinates (x',t') for the same event, please tell me how I can calculate x' and t' from x and t, in general.

Remember, here x and x' are not "lengths" - they are position coordinates. A length requires two position coordinates, and is defined as the difference between those two coordinates. Similarly, t and t' are time coordinates, not time intervals.

Previously, I suggest that the appropriate transformation for the position coordinates in ralfcis relativity would be:
$x' = x-vt$

which would be the same as the Newtonian/Galilean transformation. This has the effect of preserving "absolute" notions of distance between the primed and unprimed frames. (Note: the $v$ here is the velocity of Alice's frame, calculated using Bob's coordinates, assuming Alice's frame is moving in the positive x direction.)

Do you agree with this transformation? To compare, the Lorentz transformation has:
$x'=\gamma(x-vt)$,
but the $\gamma$ factor there means that lengths are not preserved between frames. Length contraction follows directly from this equation in SR. If you don't want length contraction in your theory, you need a different transformation equation.

Einstein made the same mistake in E=mc^2 by embedding Y with m instead of with v in momentum and then he redefined what m means as pertaining to either matter or energy. There is no conversion of energy into matter when you push a car up a hill but the car gains energy which he defined as the car gains mass. Y is a factor that is grouped with variables and in my math it is always grouped with v. As Y approaches infinity in e1quations, the equations always approach a finite value. There are no infinities in physics (except wrongly in SR) as I will show over the next 2 years.
In relativity these days, we normally keep the symbol "m"for the rest mass of an object, which is a relativistic invariant quantity (same in all frames). The notion of "relativistic mass", $\gamma m$, often comes up in pop-science discussions of relativity, but it is generally avoided in the peer-reviewed literature these days.

You have to be careful when talking about energy, because not all types of energy are included in $E=mc^2$ etc. Pushing a car up a hill increases the gravitational potential energy of the car-Earth system, but that has no effect on the kinetic or mass energy of the car at the start and end of its trip up the hill, assuming it starts and ends at rest.

I suggest we postpone discussions of relativistic energy and momentum until later - at least until we've sorted out your problems with length contraction and the like.
Not relevant to my math. She has no odometer that can measure length contraction.
Imagine a bunch of metre rulers strapped to the top of Alice's spaceship and extending out into space for light years in her direction of travel and moving with the spaceship. That's conceptually what he reference frame is. No "odometer" is required. Distances can be read off the markings on the rulers. Simple. The Earth frame is no different. It's just that the Earth's rulers are strapped to the Earth instead of to the spaceship.

She only has proper distance from the charts and proper time from her atomic clock.
When you say "proper distance" you mean the "rest length" between the start and finish lines, which is the length that Bob would measure, because the start and finish lines are stationary relative to him. Assuming all the stars and planets on Bob's chart are stationary in Bob's frame, then his chart will indeed record the "rest distances" or "proper distances" between them. The "proper time" on any one of those stars or planets, however, is the time measured by a clock at rest on one of those planets. That time can be synchronised with Bob's clocks on Earth, because the planets are at rest with respect to Bob.

Alice's "proper time" - the proper time for Alice's trip in her spaceship - is the time recorded by a clock on her spaceship, because that clock is at rest in Alice's frame. Alice's "proper time" is not in any way the same as Bob's "proper time", because their two frames are moving relative to one another. It makes zero sense to claim that, when Alice's clock reads "2 hours" that is in any way comparable to when Bob's clock reads "2 hours". The reason we can't compare is the word "when". Bob and Alice do not share the same notion of simultaneity. Moreover, Bob and Alice both see each other's clocks as running slower than their own clocks, so neither of them ever sees both clocks reading "2 hours" simultaneously, in their own frame.

You guys are so big on relativity's experimental results yet when you provide no tools that can perform the measurements you claim no tools are needed, we just know there must be length contraction because Einstein said so.
Not because Einstein said so. Because length contraction is a logical, derived, consequence of a theory which has been directly tested in many other ways and found to be accurate. You can't just throw out one derived consequence of a self-consistent theory and keep all of the rest.

If you don't think length contraction is real, you need to start from scratch with a new theory to replace SR. Specify your postulates. (You won't be able to use the one that keeps the speed of light the same in all inertial frames.) Derive your transformations. Make quantitative predictions that you can test in real-world experiments. Compare the results of those experiments to the predictions of your theory. If everything is consistent, then you may be onto a winner.

He actually said there is no such physical thing as it's due to relativity of perspective simultaneity. You can't say it's due to both actual physical contraction and also due to perspective simultaneity. Which is it? That's a contradiction in science.
You'll need to cite where Einstein said there is "no such physical thing" as length contraction. It has been accepted by scientists for 116 year now to be a real "physical thing", understood as a effect related to reference frames.

I'm just using slopes of lines and where they intersect. That's basic algebra.
That's geometry. Algebra doesn't use graphs; it is the manipulation of symbols.

You're dragging in coordinate rotations and suggesting I should learn calculus. I haven't had to use calculus since university (nor algebra until SR came along).
We don't need calculus here.

Note that the Lorentz transformations are quite different to a normal coordinate "rotation". They are sometimes described as a kind of "rotation", but that's not a very accurate description of what's going on. The Lorentz transformations clearly rescale the coordinate axes and skew them. They do not preserve time intervals or lengths in the two frames. What they preserve is the speed of light.

But I'm getting a lot of repetitious questions or comments on how this doesn't fit what relativity says as if I'm ignorant of what relativity says.
What I want to do, eventually, is to show you that your theory - your maths - is inconsistent. Either inconsistent with your own postulates (which, by the way, you haven't listed yet), or else inconsistent with real-world experimental results, or both.

To get there, I have to first understand what the fundamentals of your theory are, and how they differ from those of SR. That's why I keep asking you annoying questions about your definitions, your assumptions, and the like.

One way to shortcut the process would be for you to state the postulates of your theory. Another way would be for you to post your coordinate transformations, because I could then work backwards from those to the postulates.

(continued...)

I want to have this discussion but I'm also hoping it won't drag on forever. Do you not think you're asking the same questions over and over?
I have asked a number of questions over and over, because you did not answer them the first time I asked.

I'm getting a clearly picture of where you're coming from now, though, gradually.

Wait then. If you asked the question, I'll get around to it.
I'm actually trying to save you some time and effort, by trying to root out where we disagree. If you feel like you have to teach me about relativity or spacetime diagrams from scratch, then you're wasting your time and mine. I only need to know about how your diagrams differ from the usual Minkowski diagrams. I think at this point, I understand well enough. The answer is that they don't really differ, except that you seem to think that "proper times" in different frames are somehow comparable by your method of "Loedel simultaneity", even though no measurable variable depends on that.

SR does that, I deal with proper time and proper distance and I don't care what the perspectives of that are.
Yes you do. You calculate "proper time" in Alice's frame, for example, by using the Lorentz factor $\gamma$, or Y, if you prefer. In doing so, you implicitly recognise that Alice's clocks tick at a different "proper" rate to Bob's clocks, which means that you recognise that Alice's and Bob's "perspectives" on time are different.

You seem to want to borrow most of your equations from SR, but without acknowledging what those equations are actually about.

Relativity is not based on the illusion of perspective despite what Einstein decreed. A person 100 yds away from you is not really as tall as your thumb. It would be wild if he walks up to you and he's still as tall as your thumb.
It's interesting that you call this an "illusion of perspective". I'd say its a real effect of perspective. If you hold up a ruler in front of your eyes and measure the height of the person 100 yds away - or hold your thumb up next to him - then the person you see really is a tall as your thumb. Or, rather, the image of the person you see next to your thumb is really as tall as your thumb. But we recognise that distances on the image are not the same as distances 100 yds away, where the person is actually standing.

One way to find the "real" height of the person would be to carry your ruler 100 yds, then to measure his height with it. But that's not the only way. You could take into account how light rays propagate from the person to your eye, then do some trigonometry to "transform" the thumb-sized height measurement near your eye to a "100 yd distant" measurement of the person's "actual" height. The "transformation equations" would take into account the 100 yd distance and the angle between light rays from, say, the person's feet and the top of his head, at your eye.

Relativity using the Lorentz transformations is no different, in principle. It's just a little more counter-intuitive, since you're used to judging the heights of people at a distance "automatically" - with your two eyes measuring the 100 yds using parallax and your brain doing some internal trigonometry. In comparison, you're not used to measuring the lengths of objects moving at close to light speed. The brain doesn't do those calculations "automatically". You have no direct experience of such things, unlike your real-world experience of geometrical perspective.

There are real persistent relativistic effects, such as age difference from the twin paradox, that don't disappear when the velocity does.
Yes. But those effects are the results of a history of accelerations, which all observers can agree on. In the twin paradox, both Alice and Bob agree that Alice felt all the effects of acceleration, while Bob felt none of them, for instance. Their respective reference frames are not symmetrical in that regard - unlike situations where Alice and Bob are travelling at a constant relative velocity at all times.

There is no such thing as measurable persistent length contraction because it's only due to the relativity of perspective simultaneity which disappears when there's no relative velocity.
Time dilation similarly disappears when there's no relative velocity. All clocks at relative rest tick at the same rate.

Similarly, the thumb height of your man at a distance disappears when you go to where he's standing.

We do not agree on this at all. The clocks do not tick off time differently, the timing started or ended at different times.
Both things are true. There are relativity of simultaneity effects as well as time dilation effects.

I have not looked at general relativity but it looks devoid of controversy unlike special.
Special relativity is called "special" because it is a special case of the more general theory of General Relativity.

Specifically, special relativity falls out of general relativity when the spacetime metric is "flat". To put it another way, SR is just GR without any gravity.

GR has all the same effects as SR: length contraction, time dilation, relativity of simultaneity, constant speed of light, etc. It "just" adds in a relativistic theory of gravity. The price GR has to pay for incorporating gravity, whilst retaining the equivalence principle, is that it has to introduce curved spacetime.

This is a reply to post #160:

No such ruler exists.
You're saying that Alice can't carry a regular ruler on her spaceship?

Did you google clock handoff in relativity yet?
No. If it becomes important to our discussion, then I might.

Absolutely wrong and completely false in every way.
You should explain what's wrong, and why its wrong.

Do you have someone you could ask for the correct answer. If they are distance separated they are liable to perspectives that see different times on their clocks than they do even if they're in the same frame.
Clocks that are stationary relative to one another tick at the same rate. If they display different times, then at least one of them must have accelerated since they were last synchronised.

This discussion is devolving into an ignorance of facts instead of a difference of opinions. Unfortunately these facts don't appear in popular relativity and are only known by experts who keep a lot of secrets to themselves.
I'm not sure what you're referring to. Are you claiming you have access to secret facts that only the experts know, but aren't telling?

There are countless textbooks on relativity, as well as a lot of freely available peer-reviewed articles, as well as various pop-science accounts (which tend to leave out a lot of the maths).

Which information or "facts" do you believe the "experts" are hiding from you (or me, or the general public)?

That's why SR falls apart as a philosophy even though the math agrees with experimental results.
If Sr agrees with all the experimental results, then there must be something right about its "philosophy". Or are you claiming that its predictive power is just coincidence or something?

I will show you that's obviously not true as my math does not disagree with experimental results.
I found a couple of errors you made earlier in the thread. At one point, you were calculating speeds of light signals that were not equal to c in one or more of the reference frames, for instance.

Let's clear this up, though:
Is the speed of light the same in all inertial frames, or not, according to you? Yes or no?

If your answer is "no", then you've thrown away one of the two postulates of special relativity, and we're dealing with an entirely different theory. So, it's important I know.

This is a response to post #161.

James R said:
What are your core physical assumptions, which replace or alter the ones from special relativity?
AA. Length is invariant, time does not slow in time dilation, perspectives are mirages, there is a universal proper time that beats within every frame in agreement with the principle of relativity, MMX is explained not by a lack of medium but by a lack of material medium to which there can be no relative velocity, light messages can establish times between frames so that and the universal accuracy of atomic clocks obsolete Einstein's clock sync method, there is a basic graphical building block that can be stitched together with light messages to explain all experimental results without the rules behind spacetime paths, permanent age difference in the twin paradox is created by an imbalance in relative velocity, reciprocal time dilation as defined in SR is the true paradox, time does not beat at different rates between frames, it is merely re-formatted by proper relativity of simultaneity. There are no frame rotations, only slopes of velocity lines the most important of them being Yv and the Loedel line of simultaneity. Is that enough for now?
That's a lot of axioms, assumptions. Is it the case that you're just assuming all these things? None of them is derived from any of the others? Remember, all of SR is derived from only TWO assumptions/axioms. (Arguably, we only need one of those two, if Maxwell's equations are assumed to be correct. Then, the other one follows automatically.)

Let's look at them one by one.
AA. Length is invariant
So everybody in all frames agrees on measured lengths of objects?
Is the transformation equation $x'=x-vt$ correct, then, for your theory?

time does not slow in time dilation
I don't understand. Are you saying time dilation doesn't occur at all? Everybody's clocks remain synchronised, in all frames? From what you have written previously, that doesn't seem to be what you are saying.

Maybe you just mean that no observer sees clocks slow when they are a rest in the observer's frame, which would be consistent with SR.
What's the transformation equation between t' and t?

, perspectives are mirages
That's an axiom? What does it mean?

, there is a universal proper time that beats within every frame in agreement with the principle of relativity
What is the "principle of relativity"?
What do you mean by a "universal proper time"? In what way is this "universal" between different frames?

"Proper time", remember, is the time measured by a clock that is stationary in an observer's frame. Are you saying that all clocks in all frames tick at the same rate, so there is no time dilation? All clocks in every frame keep the same time?

If so, then why do you label Alice's "proper times" differently on your Loedel diagrams, compared to Bob's "proper times"?
MMX is explained not by a lack of medium but by a lack of material medium to which there can be no relative velocity
Is the speed of light the same in all inertial frames, or not?
light messages can establish times between frames so that and the universal accuracy of atomic clocks obsolete Einstein's clock sync method
Tell me how you sync clocks in just one frame - Bob's frame, say. Please post your method for syncing two clocks separated by 1 light year, say. Since Einstein's sync method is "obsolete", tell me what you're replacing it with.
, there is a basic graphical building block that can be stitched together with light messages to explain all experimental results without the rules behind spacetime paths
That's an axiom? An assumption?
, permanent age difference in the twin paradox is created by an imbalance in relative velocity
Again, an axiom? In SR, a "permanent age difference" is a derived result, not an assumption.

What do you mean by an "imbalance in relative velocity"? A "relative velocity" is just the velocity of some object, measured in a frame which sees that objective moving at a particular time in that frame, isn't it?

What are you "balancing" it against?
, reciprocal time dilation as defined in SR is the true paradox,
Why are you referring to SR in stating the assumptions of your alternative theory? If SR is wrong, it's wrong. That doesn't affect your theory, does it?
time does not beat at different rates between frames, it is merely re-formatted by proper relativity of simultaneity.
I don't know what that means. What does it mean to "re-format" time?

What is the "re-formatting" procedure, and when do we need to apply it?

And, again, this is an axiom?
There are no frame rotations, only slopes of velocity lines the most important of them being Yv and the Loedel line of simultaneity.
That doesn't sound like an axiom. Are the graphs in your theory derived, or just assumed? What comes first? The graphs? The equations? This long list of assumptions/axioms? What?

(continued...)

There are no coordinate frame rotations so there are no Lorentz transforms.
Relativity is "about" taking measurements in one frame of reference and deducing how they would be perceived in some other frame.

You seem to want to pretend that you're using just one set of coordinates, but in all your graphs of Bob and Alice, Bob has two coordinates (x and t, plotted horizontally and vertically on your Loedel diagrams), and Alice has a separate t' coordinate (indicated by writing that coordinate value at various points on Alice's worldline). You ignore Alice's x' coordinates, insisting instead that Alice has to use Bob's x coordinates. In fact, you deny that Alice is allowed to carry a ruler on her spaceship, for some bizarre reason.

Nobody is saying you have to keep the Lorentz transformations. But you do need to specify what alternative transformations you want to use to predict Alice's coordinates from Bob's, or vice versa.

In fact, you use things "borrowed" from SR, like the Lorentz factor, $\gamma$, to calculate Alice's $t'$ coordinates, without ever showing how this is derived from any assumption of your theory.

Depends on which stopwatch you wish to measure c because they differ on when the measurement started or stopped. v is measured by Bob's clock and Yv is measured by Alice's clock (both tick at the same universal rate but start and stop at different times). c is a velocity so it is also subject to a factor of Bob's c but it is not Y and I haven't yet worked out the math of what that factor is (probably some form of DSR). This doesn't mean either c is anything but c but there's no denying that c chasing Alice will chase her longer and farther than c returning to Bob. The Epstein diagram handles this by changing the slopes of c so this indicates to me a mathematical way around no velocity can be added or subtracted from c (hence its universal constancy) but there's still a need to somehow express the relative velocity has some marked influence on c that does not involve compromising its universal constancy.
I think you're tying yourself in knots with the Epstein diagrams. In an Epstein diagram, if Bob's world line is represented by one ray, then Alice's ray will be at an angle $\theta$ to Bob's ray, where $\sin \theta = v/c$, where $v$ is Alice's speed relative to Bob. In Epstein diagrams, light rays are always at 90 degrees to the the "ray" of the person emitting the light.

There's nothing "wrong" with Epstein diagrams, if you understand what the lengths of line segments show on those diagrams, and you understand what the angles between rays are telling you, and so on. But they are a very different picture from a Minkowski diagram, or your Loedel diagrams (which are essentially Minkowski diagrams, in reality).

If I were you, I'd forget Epstein, at least until you have a good handle on special relativity. Epstein's approach is very idiosyncratic.

Did you originally learn relativity from Epstein's book, or from a web source that used Epstein diagrams? If so, that might explain why you're so hung up on ideas of proper time and the like. Earlier in the thread, I linked a good textbook that is free online, which explains relativity in a more traditional way, using Minkowski graphs and the like.

That stems from the hyperbolic lines generated by the main equation intersecting all velocity lines at the same proper times.
Your hyperbolic lines are just lines of constant invariant parameter, $s$, for the case where $x'=0$, as I have shown. You're borrowing from SR again, maybe without even realising it.

I can see why you're having so much trouble with this. It is so drastically different from how SR explains experimental results both philosophically and mathematically. It's so different I don't think anyone will ever understand it. You're about the only person who has even tried so far and I'm being so mean.
Actually, what I'm seeing is that, to a large extent, your maths borrows from the mathematics of SR. That means that a lot of your numerical results are correct. The main problem seems to be in how you interpret the results.

It is strange that, although you calculate time dilations and effects of the relativity of simultaneity, and so on, at the same time you want to deny that those effects actually exist. You use relativity, but you also seem to want a bet each way about whether there are "absolute" or "preferred" reference frames. You don't seem to want to commit to a variable speed of light, even though your problems with measuring distances in your theory force that conclusion upon you.

It is also very clear that you don't have a good idea about the actual axioms of your own theory. I guess it's because a lot of your results aren't really derived from a consistent set of axioms of your own making at all. They are just borrowed from SR, but in a somewhat piecemeal fashion. That you can't do better than list about 12 or 15 dubious assumptions as your axioms is telling, especially when SR manages to get by with only two.

Then there is the fact that you claim to be talking about different reference frames, with different clocks etc., but you want to keep pretending you're actually only describing one reference frame. In other words, it's like you're trying to throw out the "relative" part of relativity, which would mean you're not actually engaging with the whole point of relativity.

This is a response to post #172.

So Y = 7.0888 and Yv=7.018c =x/t' and x=100000 ly so t' =14249 yrs. Same answer without any need for length contraction.
Your Yv is the "proper velocity" that we discussed previously. It uses Bob's rulers and Alice's clocks.

Your refer to the x=100000 ly as an "invariant distance", but it isn't. It's just the distance Bob measures in his frame. No mystery. As I showed, Alice measures a different distance, using her own rulers.

That you have chosen to use the Alice's "proper velocity" in Bob's frame to do the calculation doesn't mean that length contraction isn't real, or isn't happening. There are lots of different ways to calculate the same answer. Another way would be to calculate the trip time in Bob's frame, then to use time dilation to get Alice's proper time. The length contraction that Alice observes doesn't disappear just because you choose not to make use of it to calculate Alice's elapsed time.

Now if you take off for the planet you can't possibly beat light there but your Yv=7.018c so using the invariant distance of 100000 ly and your on-board clock, how fast is the light travelling measuring it using your clock from your perspective because the factor you multiply your light by must beat you to the planet when you go at Yv from your perspective. Is the factor Yc or is it some other factor like I was trying to figure out before I had to answer all these other questions.
Suppose that Bob sends out a light signal to the planet 100000 ly away, at exactly the same time Alice starts out from Earth at v=0.99c.

The light signal will obviously take 100000 years to reach the destination in Bob's frame, while Alice will take 101010 years. So, the light signal will "beat" Alice to the destination by 1010 years, according to Bob.

In Alice's frame, the light only has to travel 14107 ly, so it will take 14107 years. Alice takes 14249 years. So, according to Alice's clocks, the light will "beat" Alice to the destination by 142 years.

Earth's perspective of c is unchanged because it takes earth's distance over earth's time.
And Alice's perspective of c is unchanged, too. From Alice's perspective, light travels at c relative to her. Bob sees light travel at c relative to him.

Relativity allows mixed perspectives of time and space because it allows Yv in the 4-vector, it allows Brehme's velocity and the concept of celerity as you pointed out. You factor Y with t and x, I only need to factor it with v to get the right answers and avoid all of Einstein's Philosophical assumptions.
You're using Einstein's philosophical assumptions, without even realising it.

Where did your Y factor come from? How did you derive it? From what assumptions? Show me your derivation. If you can't, then I'll assume you borrowed it from SR.

All Alice has to measure her Yv is her clock and invariant star charts because there is absolutely no physical proof of length contraction which even in relativity is solely the result of the time function in the relativity of perspective simultaneity.
We could equally look at it the other way round, and say that the "time function" is "solely the result" of length contraction. You can see this in how I calculated the elapsed time on Alice's clock, above, for instance.

What you don't seem to realise is that length contraction and time dilation are two sides of the same coin. If you want to have a constant speed of light in all frames, you're stuck with both effects, I'm afraid. It doesn't matter that you don't like the "philosophy" of length contraction.

Nobel prize please or maybe I should have stuck with chess.
You'll need to make a significant and original contribution to knowledge to get a Nobel prize, I'm afraid.

People who have won Nobel prizes for relativity, by the way, could all do calculus. Just so you know.

Here's my next guess: do you believe that neither length contraction nor time dilation are real effects? Is that correct?
I've told you over and over in plain language and you just refuse to let it enter. So you need to tell me what you're reading in your own words because it isn't what I'm writing. Time dilation is not due to the slowing of time, length contraction is a similar time illusion of the relativity of perspective simultaneity and is physically unmeasurable by rulers. The twin paradox is the only experimental result of persistent age difference where there is no example of persistent length contraction. Now, when you read these words over and over do you see a blank page every time? What have you just read in your own words?

In fact, look up Raskar trillion fps photography that can photograph light in slow motion. Relativists say a photon crosses the length contracted universe in 0 time from its perspective (due to faulty math). So the shutter that sets the pulse width of the light being photographed should never open from the light's perspective and from our perspective, the light pulse should always be 0 wide. Yet when we open it for 1ms our time, the pulse is 1 ms wide even though it is travelling at c from our perspective so its pulse width should be zero from ours. We also see its velocity through space at c so its velocity through time should be zero yet we can see its frequency which is how fast its clock is moving.

What you don't seem to realise is that length contraction and time dilation are two sides of the same coin. If you want to have a constant speed of light in all frames, you're stuck with both effects, I'm afraid. It doesn't matter that you don't like the "philosophy" of length contraction.
Well if that's true and I proved you don't need length contraction to calculate Alice's time to cross 100000 ly in 14294 yrs, what is your rebuttal that it was done without any length contraction.

People who have won Nobel prizes for relativity, by the way, could all do calculus. Just so you know.
It looks like you can't read even my non-technical text. I said I took calculus in university and it never came up once in my career as an electrical engineer. Where's your rebuttal to my 1 question I asked? Let's concentrate on the subject rather than baseless personal attacks. You don't know me and I don't know you beyond what we see in this thread. Stop making your irrelevant assumptions.

Last edited:
If Bob observes coordinates (x,t) for a particular spacetime event, and Alice observes coordinates (x',t') for the same event, please tell me how I can calculate x' and t' from x and t, in general.

Remember, here x and x' are not "lengths" - they are position coordinates. A length requires two position coordinates, and is defined as the difference between those two coordinates. Similarly, t and t' are time coordinates, not time intervals.
Why would I care? Lorentz transforms only apply to the philosophy of SR. There is no x' in my math. Show me one physical experimental result where I would need x' in order to arrive at the correct result. As I feared your endless repetition of your questions without any rebuttal to my answers is swelling this thread to infinity. Your questions are good the first time around but what's the point of answering them if you refuse to show any indication you've even read the answers except for repeating the same questions. Where's your rebuttal to the most important question I asked you.

Last edited:
Oh god, I'm still only halfway through page 5 in this backlog.

Sure she can. She can pull out a ruler and measure something that she sees flying past her, for instance.
I'm sure all of science would just love to get a hold of this magic thought experiment ruler you possess that spews out real experimental results.

Alice has access to just as many "real clocks" as Bob does.
real clocks are those beside you or are light signals that contain clock messages or are calculated from a DSR which is delayed light signal info so they're not really real in your present time. I use proper time and don't need a perspective on Bob's clock to tell Alice what time it really is in her frame.
You wrote about permanent time differences between Alice and Bob which are discovered only after Alice and Bob are brought to rest relative to one another. That requires acceleration.
You still refuse to read about the clock handoff scenario and you don't understand that Alice and Bob can fly past or Alice can stop where Bob is and the determination of age difference is the same. Alice coming to a stop where Bob is does not cause any age difference but a stop or a clock handoff at a distance would. It's because age difference results from an imbalance in relative velocity when a frame jump occurs at separation. This isn't an opinion, do the math or you can wait until I show you the math.
I agree with you that it is not necessary for Alice and Bob to ever meet again once Alice flies away. If you're not interested in comparing their clocks side-by-side and at rest, then nobody needs to accelerate.
Completely false from an SR standpoint that's why my math is a total reversal of SR philosophy. You need to find an expert so you get this misconception out of your head. Even a stop at a distance (3 ly in my example) in the same frame (they're both relatively stopped), with all the light messages in the world does not establish permanent age difference between the two because other perspectives do not agree on that age difference. The clocks must be co-located for all to agree on the permanent age diff. This is what the prophet decreed but my math completely shows it's false, light signals are enough to establish permanent age difference.
Please don't try to tell me what I refuse to believe. Not before you've asked me, anyway.
I have asked you. I've asked you if you know about the clock handoff example in the twin paradox and I take your refusal to answer as a refusal to believe it's a fact.
You seem to be hung up on "permanent" age differences, for some reason. I agree that whenever Alice moves and then stops moving relative to Bob, there will be permanent time differences, due to Alice's accelerations. It doesn't matter whether Alice physically returns to Bob's location. She doesn't have to. She could, for example, just stop some distance away from Bob.
As I said, you need to educate yourself on this.
You're wrong. That would be a situation in which relativity could draw conclusions about their "permanent age difference". Also, once they were at rest relative to one another, every other frame would agree about their "permanent age difference" in the "stationary" frame.
permanent age difference has one definition in SR, not two. I'm not even sure what SR calls permanent age difference but when I ask this question on real physics forums, they are only familiar with the term "age difference" and have no term for the results in age difference when the two participants co-locate at the end of the twin paradox. No term at all because SR only sees proper time at co-location and does not recognize a permanent scar on proper time outside of co-location. But you'd need to consult with an expert to find this out for yourself. Good luck on that but Janus58 sounds solid to me so try asking him. Just show him what I wrote and don't try to paraphrase it in your understanding.
If Alice never stops moving relative to Bob, then they are never again both stationary in Bob's frame. They can compare their respective clock readings in various ways (e.g. by sending each other light signals carrying the time), but they don't share the same notion of simultaneity, so while they can say things like "Your clock read X at the same time my clock read Y" they will need to keep in mind that "at the same time" doesn't mean the same thing for both of them.
I get around this problem by using the Loedel perspective for a peek at proper time which is a universal god's-eye instantaneous present that SR doesn't recognize at the decree of the prophet.
introducing a third frame into the mix, alongside the original two?
You mean introducing a 5th frame to the other 4. Yes.
Remind me, though, because I'm not understanding yet: what is the "Loedel perspective"? Is that your "average velocity" (or "half velocity") frame, or something else?
half velocity as drawn on the spacetime diagrams using the relativistic combo equation.
so far our disagreement seems to boil down to a few matters
All the disagreement stems from which subject are we going to discuss. You want to discuss SR and I want to discuss the topic of this thread which is relativity and algebra. You seem to treat them as the same topic and they are quite different.
I have already posted my definition. You have yet to post yours, but it is clear from a number of your posts that your definition is different from the one I'm familiar with.
AA Maybe you can repeat back in your own words what you think my definition is separately from SR's.

Yay! Now on to questions from page 4.

Looks like I've already answered page 4 so I'll move on to page 3.

Your questions are good the first time around but what's the point of answering them
The problem is you don't answer questions in any meaningful way. I can't figure out what your basic ideas are. You seem to be avoiding direct answers for some reason. Here is a case in point:
Time dilation is not due to the slowing of time, length contraction is a similar time illusion of the relativity of perspective simultaneity and is physically unmeasurable by rulers. The twin paradox is the only experimental result of persistent age difference where there is no example of persistent length contraction.
You say, "Time dilation is not due to the slowing of time" but in the next sentence you say, "The twin paradox is the only experimental result of persistent age difference". So you say time dilation is and is not real. How are we supposed to understand what you're trying to say when you give obtuse answers like this??

So you say time dilation is and is not real
Time dilation does not cause permanent age difference in the twin paradox. This is your, and most other people's, wrong assumption because it looks like the numbers are the same therefore they must be related. When Alice continues without velocity change, the numbers at Bob=10 and Alice=8 in time dilation match the same numbers as when Alice returns to Bob which are permanent age difference numbers. They are not related at all and this can't be accepted by close minded people who only see the same numbers.

I explain velocity change at a distance is the cause of permanent age difference and go through the math of how that works. Until a velocity change or a frame jump happens, there is only the paradox or perspective illusion of reciprocal time dilation that is not due to time itself slowing but due to the relativity of simultaneity of when events are timed by the participants. There is a pandemic of not being able to read what I write and replacing that with the text of preconceived assumptions. They ignore what they don't understand instead of asking if they have the correct interpretation because they don't believe another valid interpretation is possible. James R does ask that question relatively often but then ignores the answer if it doesn't agree with what his preconceived notion of what the answer should be.

Most people have been fed comic book pop sci versions of relativity which are dead wrong. I've been fortunate to run into 3 truly and certifiably knowledgeable people on relativity in 10 yrs on forums which is why my views differ so wildly from those of pop sci and wikipedia. When they spoke, I listened because they made sense not BS. Unfortunately people who actually know something have a rule of not engaging with questions that look outside of relativity. Do you know how many nuts gravitate to physics forums and how difficult it is to separate the nuts from people who actually know math to back up their arguments? The difficulty lies with how many people actually know enough math to do the sifting. You'll never see a troll with anything but word and math salad.

Last edited:
Time dilation does not cause permanent age difference in the twin paradox. This is your, and most other people's, wrong assumption because it looks like the numbers are the same therefore they must be related. When Alice continues without velocity change, the numbers at Bob=10 and Alice=8 in time dilation match the same numbers as when Alice returns to Bob which are permanent age difference numbers. They are not related at all.

I explain velocity change at a distance is the cause of permanent age difference and go through the math of how that works. Until a velocity change or a frame jump happens, there is only the paradox or perspective illusion of reciprocal time dilation that is not due to time itself slowing but due to the relativity of simultaneity of when events are timed by the participants. There is a pandemic of not being able to read what I write and replacing that with the text of preconceived assumptions. They ignore what they don't understand instead of asking if they have the correct interpretation. James R does ask that question relatively often but then ignores the answer if it doesn't agree with what his preconceived notion of what the answer should be.

Most people have been fed comic book pop sci versions of relativity which are dead wrong. I've been fortunate to run into 3 truly and certifiably knowledgeable people on relativity in 10 yrs on forums which is why my views differ so wildly from those of pop sci and wikipedia. When they spoke, I listened because they made sense not BS..