Relativity and simple algebra II

Discussion in 'Alternative Theories' started by ralfcis, Feb 6, 2021.

  1. ralfcis Registered Senior Member

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    421
    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?
    There are no coordinate frame rotations so there are no Lorentz transforms. The ct'-axis represents 3 overlapping velocity lines (v,Yv and v_t) depending on the labelling of the units.
    I use c=x/t from both perspectives. SR also uses c=x'/t' which I don't use because I have no x'.
    Yv=x/t'
    They don't.
    We agree on the distance, we agree that our clocks run at the same rate but we disagree on when we start or stop measuring our time duration.The external observer's clock will keep running past when the car has finished covering the agreed upon distance. Relativity of simultaneity makes it impossible to agree when the time trial started or ended so the observer's clock records extra time that is irrelevant to the time trial.
    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.
    not correct
    yes
    Except Lorentz transforms are not required so there's that.
    That stems from the hyperbolic lines generated by the main equation intersecting all velocity lines at the same proper times.
    Illusions are mirages. it looks like water but there is no water. It looks like time slows but it ticks at the same rate within every frame. Perspective causes the illusion. SR defines perspective as reality and the reality of past, present and future as illusion because of SR's wrong assumption.

    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.
     
    Last edited: Feb 22, 2021
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  3. James R Just this guy, you know? Staff Member

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    ralfcis:

    I will respond to your posts above, but for now I'd like to put a thought experiment to you. Numbered questions will appear at various points. I would appreciate it if you can answer them.

    The platform of a certain train station is very long. Next to the platform, a very long train travels on a straight track. Two friends, both of whom happen to be called Bob, stand at the two long ends of the platform; I will call them B1 and B2. Two other friends, both of whom happens to be called Alice, are travelling on the train; I will call them A1 and A2.

    B1 is at the "rear" of the platform, which is the end that the front of the train passes first, as it travels past. B2 is at the "front" end of the platform. A1 sits at the rear of the train and A2 sits at the front.

    The two Bobs have laid out a whole lot of metre rulers end-to-end along the platform. It's a very long platform; they found, using their rulers, that it is actually 4 ly long, using this method.

    The two Bobs synchronise their (identical) clocks as follows. B1 sends a light signal to B2 (i.e. from the rear to the front of the platform). At the instant B1 sends that signal, B1 sets his clock to the year 2021, say. At the instant B2 receives the light from Bob, B2 sets his clock to the year 2025, figuring that the light would have taken 4 years to reach him (it had to travel 4 ly). After this procedure, B1 and B2's clocks, at opposite ends of the platform, will both be showing the year 2025, and they will tick at the same rate thereafter.
    • Q1. Is there any problem with this method for synchronising the Bobs' clocks?
    • Q2. Do you agree that, once synchronised in this way, the Bobs' clocks will remain synchronised in the reference frame of the platform, as long as the platform does not accelerate?
    The two Alices have an identical set of rulers to the ones the Bobs used. They were made in the same factory, and then some were sent to the train station while others were put on the train. There is a long corridor running the full length of the train, and the Alices lay out their rulers on the floor along that corridor, so they can measure the length of the train.

    The two Alices synchronise their (identical) clocks using exactly the same method as the Bobs, only the Alices perform the synchronisation while the train is travelling at constant velocity relative to the platform. The Alices, of course, use the rulers in the train to measure its length, not the (moving) rulers on the platform.
    • Q3. Is there any problem with this method for synchronising the Alices' clocks?
    • Q4. Do you agree that, once synchronised in this way, the Alices' clocks will remain synchronised in the reference frame of the train, as long as it does not accelerate?
    The Bobs and the Alices are each issued with a notebook in which they can jot down times that certain events occur at their respective locations.

    Here are three events:

    E1: A2 is adjacent to the rear end of the platform (where B1 is located). i.e. this is the event where the front end of the train starts passing the platform (at the rear end of the platform).
    E2: A1 is adjacent to the rear end of the platform (where B1 is located). i.e. this is the event where the rear end of the train passes the rear end of the platform.
    E3: A2 is adjacent to the front end of the platform (where B2 is located). i.e. this is the event where the front end of the train passes the front end of the platform.

    As the train goes past, the Bobs and the Alices all record the times of whichever event occurs where they are located, by writing the times in their notebooks. Then, after the train has completely passed the platform, the two Bobs walk along the platform until they meet, so they can compare notes, and the Alices walk along the train until they meet and compare notes.
    • Q5. Are there any issues with this procedure, or is it valid?
    B1 records the spacetime coordinates of E1 as (x,t)=(0, 0).
    B1 records the spacetime coordinates of E2 as (x,t)=(0, 6.6666 years).
    B2 records the spacetime coordinates of E3 as (x,t)=(4 ly, 6.6666 years).

    Note: the x coordinates are measured using the rulers previously laid out along the platform, and the two Bobs note that the times they recorded for events E2 and E3 were exactly the same. For simplicity, I will use t=0 for the times of both events, as recorded by the Bobs, rather than writing something like "Year 2030, January 28, 11:15 am", or whatever.
    • Q6. Are the coordinates for E1 and E2 reasonable?
    The two Bobs conclude, from their records of E2 and E3, that the train is 4 ly long, in their frame.
    • Q7. Did the two Bobs correctly determine the length of the train, in their frame?
    The two Bobs conclude from their records of E1 and E3 that the train was travelling at 0.6c, because the distance between B1 and B2 is 4 ly and the front of the train took 6.66 years to travel that distance.
    • Q8. Is the speed of the train correct, as determined by the Bobs?
    When the Alices finally compare notes, they find that events E2 and E3 did not occur simultaneously, according to their records.
    • Q9. Is it correct that, if E2 and E3 occurred simultaneously in the platform (Bob) frame, those events cannot be simultaneous in the train (Alice) frame?
    The two Alices record the spacetime coordinates of E1, E2 and E3 as "primed" coordinates (x',t'), one set for each event, similarly to the Bobs.

    Note: the x' coordinates are recorded by the Alices using the rulers previously laid out along the train. For simplicity, assume the Alices set t'=0 for the time of E1, as recorded by A2, rather than writing something like "Year 2030, January 28, 11:15 am", or whatever. Then, for the times of events E2 and E3, the Alices simply "subtract off" the actual date and time etc. of E1 from the dates and times on their records for E2 and E3, so that their time records are numbers of years "relative" to event E1 (as in the case of the Bobs, above).

    The event E1, then, in the Alices' frame of reference, has coordinates E1: (x',t')=(0,0).

    The Alices are stationary in the x' coordinates, so A2 is at all times located at x'=0 in that coordinate system.
    • Q10. Is there any problem with the Alices designating the coordinates of E1 in this way?
    Now, here are the remaining questions, which I would like you to answer, based on your own calculations and methods. Please show/explain your working:
    • Q11. What are the Alices' spacetime coordinates (x',t') for E2?
    • Q12. What are the Alices' spacetime coordinates (x',t') for E3?
    • Q13. Which event occurs first in the train frame: E2 or E3?
    • Q13. How long is the train, according to the Alices? Be sure to show how this length can be determined using two or all three of the given events E1, E2 and E3.
    • Q14. What is speed do the Alices measure for the platform? Be sure to show show this speed can be determined using two or all three of the given events E1, E2 and E3.
    I hope you can answer these questions.
     
    Last edited: Feb 22, 2021
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  5. ralfcis Registered Senior Member

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    In order to save myself acres of time I will copy and paste my "train in the station" ("pole in the barn", MMX experiment) from my previous forum both in how I would solve it using my math and how SR solves it using its math.

    here's how ralfativity handles the train in the station/pole in the barn scenario. It's very different from how Einativity does it. First Einativity since you're familiar with it:

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    The train is depicted as the red lines of simultaneity which are also the Minkowski rotated x-axis. Since they follow Einy's clock sync method, the train clocks are the same value at the endpoints. The train and station both have a proper length of 2 ly which is reciprocally contractible from a 2.5ly spacing between where the light signals hit the ends of the train simultaneously. The proper length of the train is distorted by the Minkowski rotation of the x-axis to make the x'-axis which is also called the train's perspective line of simultaneity created by Einy's clock sync method. The train fits into the platform at t'=0 and a light signal will hit the ends of the train at t'=1.25 simultaneously from the train's perspective and at t=.625 (back) at t=2.5 (front) from the platform. So what's simultaneous for the train is not for the platform.

    What Einativity does is join the two endpoints of the train with a line of length that is compressed by physical length contraction to fit into the station's rest length. Relativity of simultaneity is explained by this length contraction instead of vice versa.

    In ralfativity,


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    the train's length is invariant at 2 ly. There is no Einy's clock sync method so the train's ends are not subject to being sync'd. The clock values are set by other rules I outlined in this thread. The light hits the back of the train at 1.25, the train moves on and the front is hit at 1.25 much later from a universal present perspective but simultaneous from the train's perspective because both times are labelled the same. There is absolutely no need to join these two points and say that's the length of the train when those points indicate a differing duration of time from different perspectives. Just because Einy's clock sync method or my rules make the clocks say the same time, it does not mean 0 time has passed between the light hitting the back and front of the train and the extended length of the train accommodates when its ends catch the light signals. I say the extended time the difference in the start of the the train and platform stopwatches is what gives the endpoints of the length invariant train to catch the light signals. Potato/tomato.



    The true significance of what is happening can be seen from the Loedel half speed perspective which gives us a window into the instantaneous universal present.



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    I spent a lot of time describing how this perspective works in this thread but what it does is allow the light signals themselves to reveal time and compensate for the diagram's corruption of the light signals' depicted lengths. In a Loedel depiction, the pink and yellow light signals have the same length and all spacetime diagrams must contain the same information independent of depiction. That's all unimportant to this specific question right now and so is the invariant spacetime interval which maybe one day I'll find some use for. The final answer I've found is I don't draw some fake line between time points and call it physically contractible length and declare that perspective has the power to contract it because we can measure that under the motion that creates it and which disappears once the velocity disappears. To me, that viewpoint is pure insanity no matter how symmetrical and spacetimey it makes Einativity's math. If you don't understand what I'm saying, read this over and over until you can ask specific questions. I wrote this fast so I may have been imprecise in some wording. This will be impossible to grasp or even see if you can only follow the prophet and his teachings. The scales have fallen from my eyes but everyone else is still walking around with them.

    The invariant "length" of the spacetime interval comes from the video I posted. This line is like a 4 dimensional straight line as it has both time and distance components. I haven't been able to gleen any significance from its existence (except that it's a reciprocal form of relativity's prime equation from which I derive all my equations) and have discounted its relevance to this discussion.
     
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  7. ralfcis Registered Senior Member

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    My train and platform are both 2 light seconds long in ralfativity and the train is 3.125 ls long in Einativity.
    Yes, Einy sets the entire platform from end to end with the same clock time creating an artificial perspective present. Anything separated by distance can be forced to share the same clock but not the same present. I do the opposite. I use light signals to tell the time, not preset it and I reference everything to the universal, instantaneous, hidden, proper time present and derive my perspective times as needed from that basis.
    yes
    No issues so far, looks the same as my Md.
    My example uses different numbers to save me time.
    Shouldn't be the same length as the platform using Einativity because of length contraction of a moving train.
    See if the answer from my example agrees with yours.
    I'm not really paying attention to your questions but you should be able to determine what you want to find out from my example. It depends on which one of us wants to put in the effort. I put it in a while ago.
    I believe my example differs in that the middle of the train and the middle of the platform cause a light bulb to go off simultaneously at t=0 which propagates to the end of the trains. I'm going to have to dig up a much more detailed post.
    They're readable from the Md both Einy and ralfie which are different.
    What do my diagrams say.
     
  8. ralfcis Registered Senior Member

    Messages:
    421
    Here's some background info of me mathematically exploring how Einativity explains this example. Sadly you are trouncing the flow of this thread so live with the results. Terms have evolved from this past post.

    This train/MMX/football example is tough so I'll start piece by piece drawing the whole picture. The first rule that can't be violated (but Einy does anyway) is two co-located clocks that have not frame jumped must read the same time. So an STD that starts with Bob and Alice co-located or one that starts with them separated and they unite, must read the same times when together. They are actually the same STD just drawn upside down relative to one another so they have no choice but to agree that co-located clocks share the same causal present, clock time and no perspective can say any different.



    The second rule is that separated clocks at the start also share the same causal present on the same causal line of simultaneity. Einstein didn't have a concept of causal simultaneity. He made the mistake that separated clocks can share the same present on a perspective line of simultaneity. This mathematically breaks rule one so his assumption is indeed wrong. I'll show you what these words mean on an STD which doesn't make things any clearer for those who can't read them.





    This picture of an argyle sock top represents the causal time STD of the train through the station example. The green lines are the causal lines of simultaneity which join Bob and Alice's proper times. The bottom green line syncs the front and rear train clocks to zero. Einstein uses Alice's perspective to sync the clocks which forces the clocks to read different values at co-location. This can only happen if a frame jump occurs and can't happen during constant relative velocity which is what's happening here.



    The train's proper length is 2 ls. We know this because the light signals from the ends of the train to the middle travel for 1 sec to the stationary platform so they are not lengthened or shortened by the train's velocity. They are the 1st yellow light signal from the left and the 2nd pink light signal. They are the light signals that would travel through the MMX's stationary tube which has no relative motion to the light as the other tube should have had.



    Let's analyse the rear of the train first. Alice and Bob both throw their footballs causally simultaneously at t=0 on their clocks and Alice takes off running at .6c towards Bob's football. But there's a problem. According to Bob's perspective, Alice threw her football and started running .33 sec at the 1 ls separation before Bob threw his football. Alice gets a free head start due to Bob's line of simultaneity and she only runs .667 - .267 (.33 s Bob's time) = .4 sec Alice's time = .5 sec Bob's time. The pink light travelling to her also takes .5 sec Bob's time for a total of 1 sec for her to catch the ball. The original distance was 1 ls so 1 ls/ 1 sec = c preserved due to Bob's perspective taking .33 sec out of Alice's running time.



    The yellow light signal from the train to the platform reached the platform at .67 causal time and the pink light signal from the platform to the train reached the end of the train at .67 causal time which is causally simultaneous. (Causal time is independent of perspective.)

    From Alice's perspective she caught the football at .67 her time which had a velocity of c relative to her (unaffected by her velocity towards the football) but from Bob's perspective ( blue line) she caught it at .5 sec his time. This does not mean he saw her catch it before she caught it, it means their watches saw the same catch at different times on their watches. Don't know how Einy could have possibly interpreted this as Bob seeing Alice catch the ball before she caught the ball. In causal simultaneity the catch was instantaneously simultaneous and the times on the watches do not represent a causal present.



    The above shows how the MMX proved motion of one tube towards the light did not add to the relative velocity of the light. Alice's velocity towards the light did not affect her relative velocity to the football she caught because Bob's perspective gave her a head start cutting down her running time.



    Next will see how the math plays out for the perspectives using causal time as the basis of the analysis. Einy's analysis allowed for the lines of simultaneity to be zero but, in fact, only the causal simultaneity line can be zero and satisfy the rule that co-located clocks with no frame jumps must register the same time upon co-location.
     
  9. ralfcis Registered Senior Member

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    421
    Ok here's the complete picture with all the perspectives drawn for the train/MMX/football example. Everything just meshes together beautifully. It's a little bit liney so I'll have to break it down into separate STD's for my coming explanation. One thing to notice is how the train, which is 2 ls long in proper length, looks shrunk from the platform perspective (1.6 ls) and elongated (2.5 ls) from the train's perspective. Einy interpreted this shrinking and stretching of the train as it came into the station to be length contraction. No one saw the nonsense of a seemingly rubber train so I'll explain what's really happening. (Hint: it's all about how perspective simultaneity manipulates time duration and has nothing to do with length.)

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    He copied a concept from Lorentz because it was popular and then based his entire theory on a wrong concept working with the illusion of time dilation to explain the constancy of c when all along the explanation was simultaneity and perspective hiding time. To be fair, it really wasn't easy to see the truth here.
     
  10. ralfcis Registered Senior Member

    Messages:
    421
    Nobody reads or understands these STD's so I'll just start on the description of the last one without bothering to break it up.



    The left is the train going into the station or Alice running towards Bob to catch the football. Using the green line of causal simultaneity, Alice throws her football and starts running toward Bob .33 sec early from his perspective even though in instantaneous causal time her actions and Bob's throwing the football towards her are simultaneous. This is not Einstein's relativity. His theory was not based on causal simultaneity as a present independent of Bob's or Alice's perspectives. He based his reality on the illusions of Bob's or Alice's perspectives.



    So in Einstein's relativity, the blue line represents Bob's perspective simultaneity. This is a simultaneity of when Alice throws her football but not when Alice starts running towards him. She starts running .33 sec early just like in the green causal perspective but she throws the football .33 sec after she begins running towards Bob. The blue train has not shrunk but it's like when the rear hits the end of the platform, the center of the platform waits .33 sec before it throws the football simultaneously from Bob's perspective to when Alice throws her football. Because the rear of the train gets a head start, it only travels .5 sec to catch a football that travels .5sec to reach the end of the train. Same as in the causal example, the original separation was 1 ls and the time for the ball to reach Alice as 1 sec so c is preserved. This is the interferometer tube moving through the ether and it shows the relative velocity of the tube to the proposed medium of light did not surpass c. If the tube had been filled with air, it would have caused an increase of the relative velocity to the medium of sound waves so the velocity of the tube would have added to its relative velocity to the sound waves. Yes I am fluidly discussing this as if the train/MMX/football example was all one example.



    In Einstein's relativity, the lowest red line represents Alice's perspective simultaneity. This is a simultaneity of when Alice throws her football and starts running early towards Bob from his perspective. She starts running and throwing her football .75 sec early from Bob's perspective but she also starts her run not when the train end aligns with the platform but a full .4167 sec or .25 ls before that happens. The red train has not expanded but it's like when the train rear finally hits the end of the platform, the center of the platform waits .33 sec before it throws the football which is .4167 sec after Alice has thrown her football. The rear of the train doesn't get a head start this time. It has to travel .75 sec Bob's time before Bob even tosses the ball. But because Bob waits .75 sec to toss it, the train rear only travels .5 sec to catch a football that travels .5sec to reach then end of the train. Same as in the causal example, the original separation was 1 ls and the time for the ball to reach Alice as 1 sec so c is preserved. c is preserved in every case because Bob delays his pass until Alice's remaining run will take the same time as Bob's pass. Alice's passes all take different amounts of time but they always reach the platform's center (Bob) at the same time (accounting for perspective) as Alice catches her ball.



    Alice's passing of her football to Bob represents the interferometer's tube that is perpendicular to the ether. This is light's velocity through a stationary ether and a tube with 0 relative velocity to this ether. This was the standard the light's velocity in the moving tube was compared to and because the football Alice passed Bob arrived at the same time the football Bob passed to Alice, the conclusion could only be that any movement relative to c does not surpass c. The second analysis will prove any velocity away from the light does not subtract from the relative velocity to the light (right side of the STD).



    I know this will be difficult for the art history philosophers of relativistic theology because they can't look up in any of their books how exactly is c the same from all perspectives and how the MMX proves that. They can only quote scripture that says it's a done deal and is the result of length contraction working hand in hand with time dilation. Did anyone see any use of length contraction in this whole discussion? If you can show me a mathematical proof for that, I'd be glad to have a look. Oh yeah, since art history philosophers of relativistic theology don't know any math, they wouldn't be able to recognize what this proof would look like.
     
  11. ralfcis Registered Senior Member

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    421
    Posted September 9, 2019
    I left out one tedious bit of math that had me so stumped I thought I was on the wrong track. The times (.8, .67, .5)where Bob catches Alice's ball don't seem to match up with the time (.67) Alice catches Bob's ball. You need to turn the STD upside down to see what's happening. Set the top to zero and the .8 becomes .533, the .67 remains .67 and the .5 becomes .833. Now the red and blue lines of perspective simultaneity make sense because Alice's perspective of Bob's catch from the blue line of simultaneity is t'/Y = t where t' = .67, Y = 1.25 and t= .533. Alice's perspective of Bob's catch from the red line of simultaneity is t'Y = t where t' = .67, Y = 1.25 and t= .833.

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  12. ralfcis Registered Senior Member

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    This is a ponderous read and there's no need for most of it if I just stop dealing with perspectives. Causal (proper) time is all you need to solve all the problems and it will simplify my search for using DSR to tell time using light signals, real time rates vs apparent ones and explain how relative velocities to light really work in Yv and velocity through time.
     
  13. ralfcis Registered Senior Member

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    James R, all I need from you is to answer 1 question: do you agree you can cross the universe in relatively little of your ship's time if very close to c and the people you have left behind will be dust if you do so. The answer is actually very complex.
     
  14. James R Just this guy, you know? Staff Member

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    Yes, you can. The answer is not complex; it is very simple.

    In the rest frame of the Earth and whatever destination you're talking about (e.g. a planet on the opposite side of the galaxy, which we'll assume is stationary with respect to Earth), the distance that the spaceship has to travel is very far (say 100,000 ly), so even at a very high speed (say 0.99c), the trip is going to take more than 100,000 years, according to Earth clocks.

    In the rest frame of the spaceship, on the other hand, the distance between Earth and the planet is contracted to "only" 14,107 ly, which means the trip can be made in about 14249 years, according to the spaceship clocks.

    If the spaceship can go faster, we can make the elapsed time on the spaceship shorter. For instance, at a speed of 0.99999c, the trip will only take about 450 years.

    Do you agree with this, or disagree?
     
  15. ralfcis Registered Senior Member

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    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.
    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.

    Earth's perspective of c is unchanged because it takes earth's distance over earth's time. There's nothing illegal about looking at the problem this way. 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. 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. Nobel prize please or maybe I should have stuck with chess.
     
    Last edited: Feb 23, 2021
  16. James R Just this guy, you know? Staff Member

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    39,397
    ralfcis:

    This is a reply to post #150.

    I don't think you're understanding the terminology.

    In relativity, you are always free to choose one frame to be "at rest". But that's not the same as "absolutely at rest". The idea of "absolute rest" is the idea that there is some "preferred" universal frame of reference that we can say is "actually" at rest, so that all other frames have "absolute" velocities relate to the "preferred" frame.

    It is impossible to identify a frame that is "absolutely at rest", and relativity does not require such a frame. In fact, part of the point of the Michelson-Morley experiment was to show that the speed of light is the same in all directions, rather than having a speed that varies depending on the speed of the reference frame in which it is measured, relative to some "absolute frame".

    The CMB is not a frame that is "absolutely at rest", in the sense that I have defined above. The CMB itself is a bath of radiation, all of which is travelling at c. We can look at the Doppler shift of the CMB in different directions and deduce a sort of average motion of a reference frame relative to the CMB, but that doesn't mean that "average" from is in any way "absolutely at rest".

    You are free to consider the frame of the Earth to be at rest (approximately), just like you can with any approximately inertial frame. But there's nothing special or "absolute" about the Earth's frame.

    If you believe you can show that "absolute time or space" exists, you should present your evidence.

    If you were riding on a muon, at rest in its frame, how would you account for the fact that it reaches the ground before decaying?

    Note: the answer must be different to the one given by an observer on the Earth watching the muon come down. An observer riding on the muon would not see his own clock as "dilated" in any way. It would tick at the usual rate.

    I'm not sure what you mean by a "background frame". Both Bob and Alice can set up their respective reference frames (set of rulers and clocks) according to the usual method. Do you think a third frame is needed, separate from Bob's and Alice's? What for?

    A Minkowski diagram is a just a tool to help visualise what's going on. It isn't "required". We can just calculate everything using the equations of relativity, if we want to. We can draw MDs in all sorts of different frames, of course. Your "Loedel diagrams" are just MDs, essentially.

    I've done spacetime diagrams before.

    The asymmetry between the elapsed times on Alice and Bob's clocks in the twin paradox is due to the fact that one of them (Alice) accelerates three times, while the other (Bob) does not.

    I'm not sure what you're talking about, there. In Alice's frame of reference, she would be stationary and the Earth would move away from her. Conceptually, that is no different from Bob's frame, in which the Earth is stationary and Alice moves away from it.

    You seem to have some strange ideas about what photons are. Your notions are incorrect.

    You can think of a photon as being like a little billiard ball - same as an electron or whatever. It's a particle of light. For the purposes of these relativity scenarios we're discussing, you don't need to worry about wave/particle duality or any of that quantum stuff.

    Photons travel at c, always. If you stop a photon, then it disappears - it is absorbed.

    We both agree that a clock at rest relative to an observer keeps "proper time" between events that happen at that location.

    Do we agree that moving clocks tick at different rates to stationary clocks, from the point of view of an observer with a stationary clock, that he or she is comparing to the moving clock?

    But you don't have just one coordinate system. You mark off different "proper times" in different frames. That's two different time coordinates, right there. You even label the two different time coordinates on your "Loedel diagrams".

    For some reason, you won't acknowledge that there are also two different space coordinates in two different frames (in one spatial dimension).

    Yes, but Epstein diagrams, if I understand correctly, use a polar coordinate system, rather than the Cartesian one that MDs (or your "Loedel diagrams" use. The slopes of the lines in the two types of diagrams mean entirely different things.

    Those "opposite" rotations of the coordinate axes follow directly from the Lorentz transformations. Look...

    $x'=\gamma(x - vt)$
    The $x'=0$ axis (i.e. the "proper time" axis for Alice) corresponds to the line $x=vt$. Just put $x'=0$ in the transformation equation and re-arrange.

    $t'=\gamma(t-\frac{vx}{c^2})$
    The $t'=0$ axis (the set of all events simultaneous with $t'=0$ in Alice's frame) corresponds to the line $x=c^2 t/v$ (or $t = \frac{v}{c^2}x$).

    No. It's a simple matter of applying the Lorentz transformations, as I have shown above.

    Epstein's axes are entirely different from a Minkowski diagram.

    It's not a phantom construct. The lengths are what observers in each frame would actually measure, using rulers in their respective frames. The length contraction effect is a consequence of the relativity of simultaneity, as I believe you previously agreed.
     
  17. James R Just this guy, you know? Staff Member

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    39,397
    Response to your post #152:

    No. As I clearly explained, if the kicker is running along the field, then his frame is different from the frame of the stadium. They have a relative velocity. And the football has a non-zero relativity velocity to both of those two frames, different in each frame.

    Yes, all three are stationary in their own rest frames, by definition. Those three frames all move relative to one another.
     
  18. ralfcis Registered Senior Member

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    I don't think you're understanding what I'm saying. I don't care if absolute motion exists (it does not) but you can assume it as your rest frame and all the math will still work out just fine despite SR's paranoia about it. I can declare Earth is the preferred frame and my declaration is irrelevant to the math and the physics of relativity.
     
  19. ralfcis Registered Senior Member

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    421
    right, I wrongly assumed they were both stationary wrt each other but you're still missing where I take your analogy and apply it to relativity. Light is the football, the stadium is the vacuum of space, Alice is the receiver and the stationary kicker is Earth/Bob.
     
  20. ralfcis Registered Senior Member

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    421
    Great once again you have proof of this phantom concept right? I mean you keep bringing it up over and over. When do you reveal your proof? Oh wait, I forgot, we agreed that SR can't work without length contraction. So when a theory is not borne out by experimental results, what happens to that theory?
     
  21. James R Just this guy, you know? Staff Member

    Messages:
    39,397
    Response to posts #153 and #154:

    No. SR is a scientific theory that has been tested extensively over the past 116 years. Its predictions have always been in agreement with experimental findings over that period, taking into account experimental uncertainties and the like.

    Length contraction is not "invented" as part of a "philosophy" of SR. It is a derived result of the theory.

    You cannot refute length contraction without throwing away one or both of the two postulates of SR, from which the rest of the theory is derived. The theory is self-consistent and based on the postulates.

    Relativity is not an "illusion". Experiments show that time dilation and length contraction must be real effects. They are effects related to viewing things from different reference frames, but that doesn't make them "illusions" in any sense.

    That's a nonsense statement. You agree that "time rates" differ between frames. You say you agree that the relativity of simultaneity is a real effect (or do you want to backtrack now and argue that it is merely an "illusion" or a "philosophy"?). If you agree on both of those things, then it is impossible for you to create a self-consistent theory which maintains the speed of light at c in all frames, unless you accept that length contraction also occurs.

    In other words, what you're trying to do, essentially, is to throw out the postulate that the speed of light is the same in all inertial frames, on which the theory of SR rests. You should admit that this is what you want to do, rather than pretending that you agree that the speed of light is the same in all inertial frames.

    Because "perspective simultaneity" is how observers actually perceive time, in the real world.

    If you watch a car drive past you, you don't perceive its "proper time" in any way. All you perceive is the time in your own frame. And bear in mind that your world is full of things that are moving relative to you, albeit that most of them move slowly compared to c.

    Yes. That's what every scientific theory tries to do.

    Essentially, you just use SR maths, but you ignore some of the consequences of that math. It seems to me that you're uncomfortable with using the Lorentz transformations, so you claim not to need them. For some reason, you don't want to believe in length contraction, even though it seems you're happy to accept time dilation, so you claim that length contraction is not real.

    Your "Loedel lines" are based on a "special case" of the invariant spacetime parameter $s$, as I have previously shown.

    If you really think you can do what relativity cannot, probably the best thing you could do would be to propose an experiment involving actual observations or measurable quantities, showing how "your" maths would predict the results of the measurements, while the maths of SR could not. Do you have any such example?

    It seems to me you want to have a bet each way. On the one hand, you seem to agree that SR gets its numbers right all the time, and you agree with its numbers. But on the other hand, you also want to say that SR can't calculate things you can calculate, or something like that. And then there's your side argument that SR is really a "philosophy", rather than the experimentally tested and verified scientific theory it actually is.
    I'm guessing you've done something wrong, to reach that conclusion. But maybe we'll see, later.
     
    Last edited: Feb 24, 2021
  22. ralfcis Registered Senior Member

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    No they are exactly the same. They have the same labels. They describe identical equations. The axes are just swapped or in SR's case, the frame rotation is swapped.
     
    Last edited: Feb 23, 2021
  23. ralfcis Registered Senior Member

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    Mine too yet they are two completely different explanations of the facts. Are you saying it's impossible to have two theories yield the same results?
     

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