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Sure if you press them into a corner they'll all say length contraction is just shorthand but that doesn't explain away all the other parts of relativity that depend on length contraction being an actual physical phenomenon. The Lorentz transforms incorporate time dilation, relativity of simultaneity and length contraction. There'd be no need to include the last if they truly believed space itself didn't actually contract. I guess it's up to Popeye to confirm my argument is the beginning of the end for Einstein's interpretation of relativity. I can't present my case any clearer and this example of electromagnetism is the last nail in the coffin. Science and math differ in the nature of their rigorous proofs. Science requires only the simplest story to explain a set of real physical facts and Einstein's is riddled with holes and contradictions.

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Ralf;     [Not true. The MMX requires length contraction to explain the results. If nothing changed in the setup, the x axis would require more light time for a round trip than the p (perpendicular)

You do not even seem to know about the relativistic solution this apparent paradox. You don’t even have to agree with the solution — though it is correct — but it is as if you have never even heard of

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AnssiH, here's a link to my Loedel perspective question and the extents those dishonest people went to hiding the truth including anonymously deleting my supporting math.

 

https://physics.stackexchange.com/questions/520866/can-the-loedel-reference-frame-be-used-as-the-basis-for-establishing-loedel-age?noredirect=1#comment1268437_520866

 

This is science today, liars with credentials.

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https://photos.app.goo.gl/NDABXTfzdhFoeVeK8

 

I've discussed this spacetime diagram before. Anyone who understands what I'm saying can see how this diagram relates and could match the colored lines and times to the start of the pole's stopwatch, the Loedel line of simultaneity, the pole's and barn's lines of simultaneity, the start of the barn's stopwatch, the length of the barn's and pole's timeframe, the length of the pole and barn and how the pole fits the barn from 3 different perspectives. It should be very easy for anyone who understands relativity to put words to this diagram and describe the story it tells. I doubt there's anyone on the planet who could do this. Please prove me wrong.

 

PS I'm willing to help anyone learn how to use high school algebra step by step one question at a time. What is the blockage in understanding here?

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Dear Popeye,

 

  I know we had a bit of a shaky start; you thought I was a crank and I thought you were a parrot. But every time I had a question that I was stumped on, you came through. You are capable of both math and reason unlike the vast majority on philosophy/physics forums. This means you are capable of stepping outside of conventional thinking and scripture. There is an obvious contradiction in saying length contraction is due to relativity of simultaneity which is a function of time and then saying length contraction is simultaneously a function of space. The two cannot be true simultaneously from the same perspective. I don't think you're going to weigh in on this unless you can defend this contradiction because crankhood awaits.

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The real reason I haven’t weighed in, is simply because I have struggled mightily to come to a place where I am finally comfortable with Einstein’s special theory of relativity, with all of its peculiarities, and I’m a bit afraid that you may resurrect some of the old ghosts of doubt that haunted me in the past.

 

I am somewhat of a parrot because I go to where the math leads me, and the math all begins with the Lorentz transform, or the Lorentz factor which falls out quite naturally from the geometry of the MM interferometer and the null result from that experiment.

 

I don’t see length contraction as “due to” or caused by the relativity of simultaneity. That is, length contraction is not an exclusive function of time nor is it an exclusive function of space. I prefer to start where it all started, with the Lorentz transformation which tells us that length contraction, relativity of simultaneity and time dilation are all different aspects of some property, some function of, spacetime.

 

The contradiction that you see can be readily resolved by the use of partial derivatives, (which I won’t delve into in this post) but you can see this in your spacetime diagrams where objects follow different paths.

 

When an observer attempts to measure a moving object, he runs into a problem. He soon finds it is not possible to simultaneously detect two spatially separated events (such as the two ends of the object moving past a detector). In measuring two non-simultaneous events, he “ends up” measuring something that does not represent the physical length of the object in its own reference frame. He measures the object as being shorter, or contracted.

 

This isn’t an optical illusion and it also isn’t a “proper” length measurement. However, it is a valid physical length measurement in a reference frame that is in motion with respect to the object.

 

This is an affirmation of the underlying nature of spacetime, which comprises the universe that we are a part of.

 

Ralfcis, I commend your attempts to understand this on some deeper level than what I have written here.

 It may well be that you will come to the same conclusions as Einstein, but by following a different path and a different understanding; in which case you will be neither a parrot nor a crank.

 

As for me, I am content to stay on the path that Einstein blazed; I find it less risky to my sanity.

 

You are good at algebra; I suggest you take that to the next step and start working with differential calculus. It should be easy for you. Just a thought.

 

 

 

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Sure if you press them into a corner they'll all say length contraction is just shorthand but that doesn't explain away all the other parts of relativity that depend on length contraction being an actual physical phenomenon.

There actually are no parts of relativity that require length contraction to be an actual physical phenomenon. It's easy for me to make that argument confidently because length contraction is not even defined as an actual physical phenomenon in SR (unlike in Lorentz' aether theory).

 

I know a lot of people with credentials will claim otherwise. It's sometimes due to them using poor ambiguous language, and sometimes their own misconception of what relativity is. I've corrected people with credentials many times without controversy because I know how to explain it in their own language.

 

Science requires only the simplest story to explain a set of real physical facts and Einstein's is riddled with holes and contradictions.

I think when people are after a "story", as in an intuitive view / model of what reality "is like", they should realize that we will always have infinite number of possibilities open for us. That is what I refer to when I say "ontological interpretation". It's the difference betwen seeing a model as a "handy way to comprehend a situation but not really realistic" vs "what reality actually is like".

 

And it's those two views that most people mix up together without realizing that now they are bringing belief into science. Ontological views are always - by definition - beliefs. And when people point at some experiment and say that it proves some ontological belief, what they are doing is they assume that their model is the only possible way to model the situation correctly. And that is unequivocally false assumption, every time.

 

But if you understand that models are just models - figments of our imagination to make it possible to handle reality at least somehow, you also realize that it's perfectly fine to always choose the model that makes it simplest to handle a given situation - there's zero reason to just believe on faith that one of all the possible models is the one and true one.

 

Just as an example, if we ever became capable of interstellar travel, we would in a heartbeat define a universal time frame because it makes the situation far simpler to handle.

 

For good mental hygiene on relativity, just remember, it's simply about our choice regarding how do we plot down the objects in a coordinate system - and how we must transform from one inertial coordinate system to another. "why" it is so, it's a completely different topic (and it's the one the "parrots" will focus on all the time).

 

And if you are interested of following a completely epistemological reasoning as to the "why" - having nothing to do with how reality "is", that's another huge topic we can discuss too. Far outside the scope of this thread though.

 

AnssiH, here's a link to my Loedel perspective question and the extents those dishonest people went to hiding the truth including anonymously deleting my supporting math.

 

https://physics.stackexchange.com/questions/520866/can-the-loedel-reference-frame-be-used-as-the-basis-for-establishing-loedel-age?noredirect=1#comment1268437_520866

I think perhaps what confused them is that your picture is not from the Loedel reference frame, but only visualizes an in-between frame as a worldline & tilted simultaneity planes in terms of the frame of Bob.

 

It's pretty simple if you draw the whole thing in a Loedel reference frame, where both observers just move to opposite directions at same velocity. That situation is obviously symmetrical. And yields symmetrical answers. But is of course only valid for one leg of the journey, and then you have to do a switcheroo.

 

So to answer your question;

"So my question is whether "Loedel age difference" can be used as a valid term distinct from the term "age difference" used here?"

In your diagram it's all correct up until Alice changes her inertial frame; at that point "Loedel frame" simultaneity plots Alice and Bob as 4 years old at this point, as it would since you have chosen the in-between frame for your data plotting.

 

But there's a problem in the plotting of the return of Alice - if you want to now change the inertial frame to the new "in-between frame", you must do a consistent frame transformation (during which the simultaneity planes would tilt).

 

Look at the consistency requirement it this way - if you plot the entire trip, including return, in just one inertial frame - be it Alice's, Bob's or Loedel frame, you must get the same result to the moment when Alice and Bob interact again (or when anything interacts).

 

Also, if you plot the situation in some collection of inertial frames, the transformation between the frames must be such that you get the same end result no matter what frames you choose - your choice cannot actually change reality of course.

 

I have a question for you though.

 

What is in your mind the philosophical implication of choosing to use a Loedel frame? Since that can only be defined as long as you have two inertial observers. How do you plot more complex situations - and is there some sort of special meaning to the Loedel frame in your mind?

 

I'm asking because I struggle to understand what do you see as the actual difference from Relativity - and also if there's metaphysical difference I'm interested to hear your view on that part too.

 

https://photos.app.goo.gl/NDABXTfzdhFoeVeK8

 

I've discussed this spacetime diagram before. Anyone who understands what I'm saying can see how this diagram relates and could match the colored lines and times to the start of the pole's stopwatch, the Loedel line of simultaneity, the pole's and barn's lines of simultaneity, the start of the barn's stopwatch, the length of the barn's and pole's timeframe, the length of the pole and barn and how the pole fits the barn from 3 different perspectives. It should be very easy for anyone who understands relativity to put words to this diagram and describe the story it tells. I doubt there's anyone on the planet who could do this. Please prove me wrong.

 

Sorry I have no idea what you mean by that diagram. Don't know what the different colored lines represent. I can make a wild guess that this is a diagram showing the concept where all objects are moving at constant velocity through spacetime, and more velocity attributed on spatial axes can be seen as less velocity attributed to time axis? Maybe :shrug:

 

-Anssi

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Ok fair enough but this statement while partly true does not exclude other math that flows naturally out of MM.

 

 "the math all begins with the Lorentz transform, or the Lorentz factor which falls out quite naturally from the geometry of the MM interferometer and the null result from that experiment."

 

The Lorentz transform is a hodge podge of 4 concepts when there is only 1 (relativity of simultaneity). I went through the MM math extensively in this thread rejecting all the superfluous assumptions Einstein made. The Lorentz transform is not the beginning, these assumptions are what the Lorentz transforms unnaturally fall out of. Einstein and others constructed this beautiful fairy tale of spacetime that works amazingly well except the true reality is not subjective, time and space are not two sides of the same coin and there is a universal instantaneous present underlying reality. Yeah, old school stuff but you just redefine old school a little and there's no need for Einstein's ideas (and you'll discount anything further I have to say).

 

 "However, it is a valid physical length measurement in a reference frame that is in motion with respect to the object.'

 

This would make anything true from the right perspective. Mirages are not water, you are not really 2 inches tall when you're 100 yds away from me. Einstein made perspective true in order to get rid of universal time but it's still illusion and universal time, as I've defined it, is objective reality. Neither philosophy can be unproven but while Einstein's theory only leads to a concept of spacetime, mine leads to far deeper conclusions of why things work the way they do. 

 

"He measures the object as being shorter, or contracted."

 

He does not. He measures time at the start and endpoints and the assumption is everything in between is a duration or a length. Hard not to make this conclusion as it seems infinitesimally intuitive. If you carefully go through my train in the station example, you'll see the endpoints of the train are not joined by a length or a time duration (Lorentz transforms try to deal with this apparent paradox of coordinate points and durations between them). Perspective is a hysteresis around a central truth and when you deal with the perspective as truth, you end up with false conclusions.

 

The crack in Einstein's view is that length contraction is a true physical phenomenon. Relativists agree when it suits them. Yeah it's not true but it allows us to visualize things. Neither time slowing or length contracting or perspectives are true, only relativity of simultaneity is which does not require the Lorentz transforms at all. I have proven this all mathematically (all the higher math can't refute lower math because math is consistent) so it should be possible for someone out there to point out any mistake in the math not in the discomfort it causes to their beliefs. The problem is effort. Why explore other theories when the existing one is adequate. That is the true answer yet on Physics Stack Exchange, they'd rather delete posts than deal with legit questions. That's not science. This is the only place I've been allowed to speak as who really cares what anyone says in an insane asylum. But I appreciate this is the only place where I'm allowed to continue.

 

"It may well be that you will come to the same conclusions as Einstein"

 

This is not possible so long as I find no evidence to steer me off the path I'm on. I'm not on it to be novel, I'm on it because I find Einativity completely wrong, none of it's right even though it totally works.

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Again Anssih, where have you been all my life? You are so correct in your thoughts (and so is Popeye) so why is the world so painfully dumb? 

 

Yes I didn't draw the Loedel spacetime diagram. I borrowed the concept to give a name to a reference frame that defines a line of simultaneity which pokes a window onto the universal instantaneous present. It shines a light on the unseeable. Also, I was forced to not discuss what happens after Alice changes direction. My math that describes this has no relation to relativity but it has been discussed at length in this thread. As for the diagram the only way to decipher it is to put tremendous amount of effort into it. If I just give the answer, the answer will not sink in. With you, maybe a quick explanation would work but you'd have to repeat back what I tell you in your own words which is the only way to know you're getting it. Unfortunately,  I have no time right now though.

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The real reason I haven’t weighed in, is simply because I have struggled mightily to come to a place where I am finally comfortable with Einstein’s special theory of relativity, with all of its peculiarities, and I’m a bit afraid that you may resurrect some of the old ghosts of doubt that haunted me in the past.

Aaaalright, it's time to wake up some ghosts I'm afraid :)

 

But don't worry, if you can follow me, you will find the ghosts are not real after all. If anything I say sounds controversial, check your sources.

 

I am somewhat of a parrot because I go to where the math leads me, and the math all begins with the Lorentz transform, or the Lorentz factor which falls out quite naturally from the geometry of the MM interferometer and the null result from that experiment.

Yes but you should be aware where Lorentz transformation came from and what it represented in Lorentz' opinion. There's couple of plot twists early on that throw most people off the scent immediately.

 

I'd suggest you very carefully dissect my discussion about it in that long post a while ago in this same thread;

http://www.scienceforums.com/topic/35098-relativity-and-simple-algebra/page-73?do=findComment&comment=385984

 

What you should take away from that is how for natural observers it is always possible to think of it as representing a sort of "universal disturbance in actual information propagation" (whatever it is that makes this world work), or think of it as representing observer freedom to plot the state of the world in terms of any reference frame.

 

I don’t see length contraction as “due to” or caused by the relativity of simultaneity. That is, length contraction is not an exclusive function of time nor is it an exclusive function of space. I prefer to start where it all started, with the Lorentz transformation which tells us that length contraction, relativity of simultaneity and time dilation are all different aspects of some property, some function of, spacetime.

Now here you have the cart in front of the horse. This is a common misconception, because the way Relativity is taught usually is to discuss it in terms of Minkowski spacetime. And it gives everyone an upside down impression of what's going on. A lot of people have the impression that the theory is somehow about spacetime. It's not. Spacetime is about the theory, but the theory is not about spacetime in any shape or form.

 

Let's get back to the beginning; the original paper by Einstein is in here;

 

http://www.fourmilab.ch/etexts/einstein/specrel/specrel.pdf

 

Chapter one is called definition of simultaneity. The reason why it's called this is one very simple realization - if you can't measure one-way speed of time, you also cannot actually know what is the exact state of the world at any given moment. This means we have several ways to choose for how to define it, and Einstein discusses only one of those choices, and it's consequences to bunch of other definitions (regarding spatial and temporal relationships - but not spacetime).

 

The fact that speed of light cannot possible be measured is completely non-controversially true, but nowadays often forgotten because everyone are too busy using Einstein convention to remember where it came from. Basically Minkowski cult has made it appear as if we know what the speed of light is - but actual fact is that it's easy to show that it's not possible to measure that speed (Let me know if this is new information to you btw because I'm curious).

 

This is the one and only concept you must completely comprehend, and everything else will fall right out of it. The entire paper from Einstein is devoted to explain how everything else falls out from it (but it's not really that hard to figure out yourself TBH)

 

You can in fact form an intuitive sense of relativistic transformations once you realize this one bit (and also a sense of how it's really probably just a mental hack - nothing to do with reality).

 

Here's one good way to understand it; realize that you are an observer sitting in one spatial location, constantly receiving information from the reality at some finite speed C. Realize that you have no way of knowing how fast that information was moving towards you (one-way speed is fundamentally unknowable). You have no way of knowing if it's coming faster from one direction, and slower from another. You can't synchronize clocks to find it out, because you don't know that speed.

 

Now, since you can't find this speed out, the flip-side of that same coin is that you can also simply assume that the information is propagating at speed C towards you from all directions. If you do, you now have a convention for plotting the state of things around you in a simple spacetime diagram.

 

But on the same token, you are also free to simply assume that the propagation is happening faster in one direction but slower in another (i.e. follow something another observer might have assumed). This will give you another convention for plotting the state of things around you in a simple spacetime diagram.

 

There is no way for you to find out which assumption is correct, because your only "feelers" to probe the world are governed by this very same propagation speed. You are part of this world, and every measurement apparatus is also part of this world - affected the same way by the maximum information propagation speed there is.

 

So if you imagine a situation with multiple observers standing in the same spot, but each holding their different assumption about how fast information propagated to them, you can see how each observer would have their own definition of simultaneity, and each one would plot the state of the world differently.

 

If you connect that definition to the velocity of each observer, you can think of each observer as simply having a different idea in their mind regarding "how long time ago" some signal departed, even though they all might be receiving the same signal at the same time in the same location (just imagine a moment when these observers cross paths).

 

If you can visualize the above in your head, you can see how the assumption of different C transforms "simultaneity planes" -> you can freely say that you were approaching a signal you just received, or if you want to assign speed C to the signal, you might also just say it departed "earlier" so to fix the speed exactly to C (or whatever value you want), so long that two-way speed (to opposite directions) is exactly C (this is something you can actually measure).

 

And this sort of transformation - when done correctly - can be seen as sort of "scaling" all the events and causal connections that make up the the universe. As long that this transformation applies to absolutely everything in the universe (i.e. it's actually associated with "maximum signal speed" available to you), there's no way for a natural observer to tell any difference because they also partake in any "scaling".

 

It's a common misconception that relativity is somehow describing what happens to "objects", because that's how it's often discussed. But it's much more proper to look at it as coordinate system transformation. What Einstein is talking about in that paper is what is a valid way to do that coordinate transformation between different choices of simultaneity. As in, how would we plot data in a spacetime diagram in self-consistent fashion, given the fact that we have a free choice of reference frame.

 

This fact is a bit lost since he assigned each inertial frame with their own choice, but basically we are free to choose any frame we want for our data plotting, and we must get the same end result - that is what makes a theory valid.

 

Once you realize it's really just about data plotting, then the following should make a whole lot more sense to you;

 

When an observer attempts to measure a moving object, he runs into a problem. He soon finds it is not possible to simultaneously detect two spatially separated events (such as the two ends of the object moving past a detector). In measuring two non-simultaneous events, he “ends up” measuring something that does not represent the physical length of the object in its own reference frame. He measures the object as being shorter, or contracted.

 

This isn’t an optical illusion and it also isn’t a “proper” length measurement. However, it is a valid physical length measurement in a reference frame that is in motion with respect to the object.

There is no such thing as "measurement" of length contraction. Length contraction is just what happens on a spacetime diagram, as a direct logical consequence of someones definition of simultaneity. It's very easy to see, once you realize that in order to "measure" the length of an object that is moving, you must be able to mark down its front and rear end simultaneously. Thus, it is absolutely a function of your definition of simultanity. This is why it also is dependent on concepts of time and space. Keyword concepts.

 

Another way to put it, relativistic convention is specifically about how to plot something we have no way of measuring (due to finite speed of information).

 

I guess the key point that is lost on everyone nowadays is that Relativity is not about speed of light actually being C to everyone, but about our ability to plot data with that assumption, and our ability to transform between observers under this assumption. Nothing more, nothing less.

 

 

This is an affirmation of the underlying nature of spacetime, which comprises the universe that we are a part of.

And this is completely false assumption - basically what I've been discussing in my past posts. There's zero reason to see any of that as affirmation about the nature of spacetime, just because spacetime ontology is one valid option out of many. Lorentz aether philosophy is perfectly valid also because the difference is merely philosophical - that one of the frames out there is actually representing actual simultaneity of reality - simply beyond our ability to measure it.

 

Minkowski made an argument that the relationships discussed by Einstein are not just handy ways to represent the logical relationships between our concepts of space and time, but instead direct features of actual reality - as features of "spacetime" that is an entity actually exists. The only problem is - this is purely an assumption, and it leads into rather wacky requirement that something that has not yet happened "for you", has already happened for another person just passing you by in another frame.

 

Basically since it's not possible to make the argument that the state of the reality actually changes just by us choosing to plot it into a different reference frame, the only option is that time does not actually exist, but instead reality is static block of events where conscious minds only think time exists (and thus conscious minds are not part of the mechanisms of reality itself? What?).

 

If you really dig into it, you should see how fringe idea it actually is, given the fact that this all really just started from the fact that we can't reach information about reality faster than some finite speed :shrug:

 

It is really ironic that because Minkowski's view is how Relativity is always taught and discussed, nowadays the idea that universe is actually dynamic is often taken as the fringe view...

 

Now, if you can see how Minkowski's view of static reality is quite a stretch from where we started (from the original paper), and not in any shape or form required by it, I suggest you take the next step and think about what would Lorentz transformation imply, if reality actually is dynamic - if there actually is an absolute simultaneity that we just can't measure.

 

The model you arrive at is not very strange at all. If you manage to take the effect of finite information propagation speeds completely into account in every mechanism in self-consistent manner, you get exactly to the same observable effects for natural observers as SR, but for somewhat different reasons than what Minkowski thought (and there's many metaphysical flavors you could go from here too).

 

And in that view, length contraction "really happens" in more actual way, but still also we are not really able to measure it in any direct sense because our attempts are still limited by that same finite information speed.

 

-Anssi

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Anyway Popeye I hope you agree that relativity depends on length contraction being a physical phenomenon no matter what the spurts say on the PSX. Without this fact, relativity ceases to exist as a theory. I still need a proof that length contraction is real because I can explain every relativistic phenomenon without any need for it. I thought maybe this concept of electromagnetism being dependent on relativity would be that proof but it totally phizzled like in every other example I've disproved. Surely there exists one example of length contraction that can't be explained away by relativity of simultaneity or as the equivalent of time dilation as purely a time phenomenon.

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 "universal disturbance in actual information propagation"

 

This is the deeper theory than spacetime I was alluding to. Is the propagation of information the basic reality of the universe.

 

"The fact that speed of light cannot possible be measured is completely non-controversially true"

 

I totally disagree but you undermine my counterproof by saying atomic clocks can't be definitively universally accurate. They can if you believe there's such a thing as proper time and they measure it.

 

"no way of knowing how fast that information was moving towards you"

 

But you do though. You can see the normal rate of time in your own frame with an atomic clock. If the readings of other clocks don't tick at the same rate, you know by the doppler shift ratio (DSR) that they are moving. Again, this doesn't depend on Einy's clock sync method but on the universality of proper time as measured by atomic clocks.

 

There's an important distinction between the DSR and time dilation. Why is time dilation .8 at .6c and DSR .5 at .6c separating when both are supposedly indicating a slowing of time at different rates? Time dilation is defined as time itself slowing while DSR is the rate of clock information getting more delayed as the clock moves away from you. Of course, in my theory, there's no such thing as time slowing, only a discrepancy in simultaneity of when you start the stopwatches to measure time. There's a special case of time flowing at different rates when the relative velocity is not the same after a frame jump which I go to in great detail in this thread. It is the twin paradox phenomenon but I don't yet know what to call what is happening to proper time itself.

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Anyway Popeye I hope you agree that relativity depends on length contraction being a physical phenomenon no matter what the spurts say on the PSX. Without this fact, relativity ceases to exist as a theory. I still need a proof that length contraction is real because I can explain every relativistic phenomenon without any need for it. I thought maybe this concept of electromagnetism being dependent on relativity would be that proof but it totally phizzled like in every other example I've disproved. Surely there exists one example of length contraction that can't be explained away by relativity of simultaneity or as the equivalent of time dilation as purely a time phenomenon.

 

 

Yes, I do agree. As I wrote earlier: “when an observer attempts to measure a moving object, he runs into a problem. He soon finds it is not possible to simultaneously detect two spatially separated events (such as the two ends of the object moving past a detector). In measuring two non-simultaneous events, he “ends up” measuring something that does not represent the physical length of the object in its own reference frame. He measures the object as being shorter, or contracted”

 

This difference in length is quantified by the Lorentz factor, which falls directly out of the geometry of the MM interferometer, and the null result from that experiment. If the length in the frame of the instrument is [math]L_0[/math], then the transformed length in the moving frame is [math]L_0 \gamma[/math]

 

The length [math]L_0 \gamma[/math] is as physically real as any other length you can think of.

 

But I doubt very much you will ever find an example for length contraction that can't be explained also by the relativity of simultaneity, as they are two sides of the same coin.

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Aaaalright, it's time to wake up some ghosts I'm afraid :)

 

But don't worry, if you can follow me, you will find the ghosts are not real after all. If anything I say sounds controversial, check your sources.

 

Yes but you should be aware where Lorentz transformation came from and what it represented in Lorentz' opinion. There's couple of plot twists early on that throw most people off the scent immediately.

 

I'd suggest you very carefully dissect my discussion about it in that long post a while ago in this same thread;

http://www.scienceforums.com/topic/35098-relativity-and-simple-algebra/page-73?do=findComment&comment=385984

 

What you should take away from that is how for natural observers it is always possible to think of it as representing a sort of "universal disturbance in actual information propagation" (whatever it is that makes this world work), or think of it as representing observer freedom to plot the state of the world in terms of any reference frame.

 

Now here you have the cart in front of the horse. This is a common misconception, because the way Relativity is taught usually is to discuss it in terms of Minkowski spacetime. And it gives everyone an upside down impression of what's going on. A lot of people have the impression that the theory is somehow about spacetime. It's not. Spacetime is about the theory, but the theory is not about spacetime in any shape or form.

 

Let's get back to the beginning; the original paper by Einstein is in here;

 

http://www.fourmilab.ch/etexts/einstein/specrel/specrel.pdf

 

Chapter one is called definition of simultaneity. The reason why it's called this is one very simple realization - if you can't measure one-way speed of time, you also cannot actually know what is the exact state of the world at any given moment. This means we have several ways to choose for how to define it, and Einstein discusses only one of those choices, and it's consequences to bunch of other definitions (regarding spatial and temporal relationships - but not spacetime).

 

The fact that speed of light cannot possible be measured is completely non-controversially true, but nowadays often forgotten because everyone are too busy using Einstein convention to remember where it came from. Basically Minkowski cult has made it appear as if we know what the speed of light is - but actual fact is that it's easy to show that it's not possible to measure that speed (Let me know if this is new information to you btw because I'm curious).

 

This is the one and only concept you must completely comprehend, and everything else will fall right out of it. The entire paper from Einstein is devoted to explain how everything else falls out from it (but it's not really that hard to figure out yourself TBH)

 

You can in fact form an intuitive sense of relativistic transformations once you realize this one bit (and also a sense of how it's really probably just a mental hack - nothing to do with reality).

 

Here's one good way to understand it; realize that you are an observer sitting in one spatial location, constantly receiving information from the reality at some finite speed C. Realize that you have no way of knowing how fast that information was moving towards you (one-way speed is fundamentally unknowable). You have no way of knowing if it's coming faster from one direction, and slower from another. You can't synchronize clocks to find it out, because you don't know that speed.

 

Now, since you can't find this speed out, the flip-side of that same coin is that you can also simply assume that the information is propagating at speed C towards you from all directions. If you do, you now have a convention for plotting the state of things around you in a simple spacetime diagram.

 

But on the same token, you are also free to simply assume that the propagation is happening faster in one direction but slower in another (i.e. follow something another observer might have assumed). This will give you another convention for plotting the state of things around you in a simple spacetime diagram.

 

There is no way for you to find out which assumption is correct, because your only "feelers" to probe the world are governed by this very same propagation speed. You are part of this world, and every measurement apparatus is also part of this world - affected the same way by the maximum information propagation speed there is.

 

So if you imagine a situation with multiple observers standing in the same spot, but each holding their different assumption about how fast information propagated to them, you can see how each observer would have their own definition of simultaneity, and each one would plot the state of the world differently.

 

If you connect that definition to the velocity of each observer, you can think of each observer as simply having a different idea in their mind regarding "how long time ago" some signal departed, even though they all might be receiving the same signal at the same time in the same location (just imagine a moment when these observers cross paths).

 

If you can visualize the above in your head, you can see how the assumption of different C transforms "simultaneity planes" -> you can freely say that you were approaching a signal you just received, or if you want to assign speed C to the signal, you might also just say it departed "earlier" so to fix the speed exactly to C (or whatever value you want), so long that two-way speed (to opposite directions) is exactly C (this is something you can actually measure).

 

And this sort of transformation - when done correctly - can be seen as sort of "scaling" all the events and causal connections that make up the the universe. As long that this transformation applies to absolutely everything in the universe (i.e. it's actually associated with "maximum signal speed" available to you), there's no way for a natural observer to tell any difference because they also partake in any "scaling".

 

It's a common misconception that relativity is somehow describing what happens to "objects", because that's how it's often discussed. But it's much more proper to look at it as coordinate system transformation. What Einstein is talking about in that paper is what is a valid way to do that coordinate transformation between different choices of simultaneity. As in, how would we plot data in a spacetime diagram in self-consistent fashion, given the fact that we have a free choice of reference frame.

 

This fact is a bit lost since he assigned each inertial frame with their own choice, but basically we are free to choose any frame we want for our data plotting, and we must get the same end result - that is what makes a theory valid.

 

Once you realize it's really just about data plotting, then the following should make a whole lot more sense to you;

 

There is no such thing as "measurement" of length contraction. Length contraction is just what happens on a spacetime diagram, as a direct logical consequence of someones definition of simultaneity. It's very easy to see, once you realize that in order to "measure" the length of an object that is moving, you must be able to mark down its front and rear end simultaneously. Thus, it is absolutely a function of your definition of simultanity. This is why it also is dependent on concepts of time and space. Keyword concepts.

 

Another way to put it, relativistic convention is specifically about how to plot something we have no way of measuring (due to finite speed of information).

 

I guess the key point that is lost on everyone nowadays is that Relativity is not about speed of light actually being C to everyone, but about our ability to plot data with that assumption, and our ability to transform between observers under this assumption. Nothing more, nothing less.

 

 

And this is completely false assumption - basically what I've been discussing in my past posts. There's zero reason to see any of that as affirmation about the nature of spacetime, just because spacetime ontology is one valid option out of many. Lorentz aether philosophy is perfectly valid also because the difference is merely philosophical - that one of the frames out there is actually representing actual simultaneity of reality - simply beyond our ability to measure it.

 

Minkowski made an argument that the relationships discussed by Einstein are not just handy ways to represent the logical relationships between our concepts of space and time, but instead direct features of actual reality - as features of "spacetime" that is an entity actually exists. The only problem is - this is purely an assumption, and it leads into rather wacky requirement that something that has not yet happened "for you", has already happened for another person just passing you by in another frame.

 

Basically since it's not possible to make the argument that the state of the reality actually changes just by us choosing to plot it into a different reference frame, the only option is that time does not actually exist, but instead reality is static block of events where conscious minds only think time exists (and thus conscious minds are not part of the mechanisms of reality itself? What?).

 

If you really dig into it, you should see how fringe idea it actually is, given the fact that this all really just started from the fact that we can't reach information about reality faster than some finite speed :shrug:

 

It is really ironic that because Minkowski's view is how Relativity is always taught and discussed, nowadays the idea that universe is actually dynamic is often taken as the fringe view...

 

Now, if you can see how Minkowski's view of static reality is quite a stretch from where we started (from the original paper), and not in any shape or form required by it, I suggest you take the next step and think about what would Lorentz transformation imply, if reality actually is dynamic - if there actually is an absolute simultaneity that we just can't measure.

 

The model you arrive at is not very strange at all. If you manage to take the effect of finite information propagation speeds completely into account in every mechanism in self-consistent manner, you get exactly to the same observable effects for natural observers as SR, but for somewhat different reasons than what Minkowski thought (and there's many metaphysical flavors you could go from here too).

 

And in that view, length contraction "really happens" in more actual way, but still also we are not really able to measure it in any direct sense because our attempts are still limited by that same finite information speed.

 

-Anssi

 

I mean no offense, but all I see here is lots of flowery words, well written, but nothing substantial. No ghosts have been stirred up, none at all.

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With time dilation being the 3rd side and. also, as you taught me, closing speed. On wiki people have examples that certain particle collisions or group particle movement can't be explained other than through real length contraction. Even Feynman said quarks can only collide when they bulge out of a proton like blueberries out of a pancake but that's just an idiotic thing for him to say. My formula is v'=Yv. The concepts of length contraction and time dilation are joined in that formula because they can't be separate.

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Popeye something you said bothered me and something I said bothered me and I think I have the answer. You said length has time incorporated in it into some relativistic hybrid substance and I said my coordinate endpoints don't care about their time duration or length separation. But now I think this hybrid substance is invariance from all perspectives. Length must contract when time dilates to make the length of the spacetime path invariant. It's not enough that the proper length of a train and that of a station are the same, there is some hybrid spacetime path time/length  invariance that needs to be satisfied. I need to plug in coordinate values into ct'2 = ct2 - x2 to see if I'm on the right track and whether my theory satisfies invariance if that indeed is a requirement of any coordinate rotation in mathematics. If this is the missing piece I'd think someone would've mentioned it years ago, "Your not taking into account invariance." Well let's see where this leads.

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I'm trying to get my head around what I'm trying to prove. A train coming into a station has a proper length at velocity zero. I'm expecting the invariant length should remain the same from the platform's perspective no matter what the incoming speed of the train? I have to check if this is true and the significance of it being true. In Einativity, the formula for invariant length includes both length and time but in ralfativity length is already invariant so there would be a different formula for invariance. That formula would also need to calculate an invariant length of the train no matter its velocity. I'm not sure if any of this makes sense yet. Maybe I need to check that the invariant length must be the same from any perspective velocity of the train. I can check this last point by doing some calculations on my train in the station example to get me started but I don't know what I'm looking for yet.

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