md65536

Right. Gravitational redshift/blueshift is the correct term. I apologize for the huge pile of mistakes. What are [math]r_1[/math] and [math]r_2[/math]?

Suppose you have an elevator appropriately fixed in a uniform gravitational field. The observer at the "top" is still at a higher gravitational potential. Even though the force of gravity doesn't change between the two observers, there is still work involved in moving a mass from one location to the other. So there is still Doppler shift observed by the two, and their clocks do not remain in sync. So they don't have to observe the other having the same coordinate acceleration as their self. I don't think there is any room here to distinguish between a uniform proper acceleration and uniform gravitational field.

In this paper I'm talking about simultaneity, not synchronization. Following the comments by xyzt and uncool, I've rewritten the intro paragraph to make it clearer and remove errors and ambiguity: "In the definitive work [1] on special relativity (SR), Albert Einstein acknowledges that an assumption is required in order to define a common time between two events at separate respective locations A and B. To answer this, Einstein defines what is now called standard simultaneity, establishing that the time required for a light signal to travel from A to B is the same as the time required for a signal to travel from B to A. While it is generally acknowledged that this remains an assumption, it is consistent with observation and is used in the physical representation of time throughout modern physics. Einstein justifies the definition by its practical benefit of independence of observer standpoint with the clock, but it is tempting to presume that the definition has a fundamental physical basis, since it is consistent with observations of an invariant speed of light and with a classical interpretation thereof."

The colored parts explain what I quoted from the reference I cited. I explained this in post #21. Are you saying Einstein was wrong? Your objections were also replied to in post #19. ---- Since Einstein only points out the need for an assumption, and then defines "time", he never explicitly assumes that his definition of time is true. He only provides the definition, at most assuming that it's consistent. Edit2: He also makes it clearer that he's speaking of the time of events at A and B, not the clocks themselves. So I'll change the intro's first 2 sentences: "In the definitive work [1] on special relativity (SR), Albert Einstein acknowledges that an assumption is required in order to define a common time between two events at separate locations. To answer this, Einstein defines what is now called standard simultaneity, establishing that the time required for a light signal to travel from an observer O to an observer P is the same as the time required for a signal to travel from P to O." I see now how "common time between two separated clocks" may imply clock synchronization (especially if "time" refers to elapsed time rather than an event's time coordinate) when what I meant to speak of was only simultaneity.

Thanks. The speed of light is isotropic. Experiments confirm it. The point is moot because it is implied by the postulates of relativity, which I've assumed are true in my paper. I never speak of a speed of light other than c. Einstein defined "time" such that the "time" of the light signal from A to B is the same as that from B to A. He doesn't define in in terms of speed. Einstein was very careful and he avoided making any implicit assumptions that I'm aware of, such as your assumption that equal timing and equal speed are the same thing without any underlying assumptions or whatever. In the paper, I'm using an alternative definition of time, but maintaining the standard definition of speed, for which all measurements of velocity agree with Einstein's model. Perhaps it's a bit tricky, but all of the assumptions and definitions are explained, and all of the conclusions are reasoned out, and it is all done in agreement with SR. The isotropy of speed of light does not confirm Einstein's definition of time, it is simply mutually consistent with it. In the translation of Einstein's paper as cited, he says: The assumption I'm referring to is the "further assumption" that Einstein refers to. He is cleverer than I am, he calls it a "definition", but it is an answer to the need for an assumption that he identified. I could probably write the intro paragraph better, but I think it's fair to say that the definition of simultaneity given by Einstein is used as an assumption. I don't think I have. Einstein defined "time" according to the equal timing of a signal between A and B and vice versa (see his quote above), and that definition has come to be known as "Einstein simultaneity" or "standard simultaneity". It applies whether clocks are synchronized or not. Einstein then uses his definition of "time" to define synchronization of clocks, but my paper doesn't require synchronized clocks.

Yes, it works. What I attempt to prove is that an alternative also works. I also try to explain why Einstein's model works in terms of the new model, in Section 3. I look forward to hearing what you think of the whole paper! Thanks.

Are there any that don't assume standard synchronization? Or is there anything that proves that Einstein's assumption is no longer just an assumption? There are no errors in the first intro paragraph. The statement you highlighted in red is true and it comes from reference [1]. The statement you highlighted in blue is true, and as you say has been confirmed by experiment.

Please stop making false accusations. I downvoted your "definition" of my paper as crap, before you even posted the criticisms of the content. Anyway you're the only one who has commented on the content, and I'm thankful for that. I would like to stick to discussing the content.

Thanks for the reply to the content. 1) I don't think I implied any connection between the two??? I simply introduced the topic as it is described in the reference I cite (Einstein's 1905 paper on special relativity). I don't think that I improperly conflate the two, and I acknowledge in the paper that SR with standard simultaneity keeps the two separate. Edit: Now that I think about it, later I claim that the two are measured only together, not separately. I say "the relativistic effect (of time dilation) is measured only in conjunction with the delay of light, and there is no visible distinction between the two." Is this false? 2) Nothing in the paper contradicts this. I present an alternative model, which also works. In the end I conclude that the new model doesn't invalidate the old one. I'm building on SR, not trying to refute it. Edit: Light speed isotropy is confirmed using a measurement of speed that assumes standard simultaneity. Einstein knew what he was doing and expressed it without implicit assumptions, even though others since (notably those dealing with conventionality of simultaneity, I've found) include such assumptions without acknowledging them. I've gone straight to the source of the assumption where he laid it out perfectly clearly. To speak of one-way measures of the speed of light involves an assumption of simultaneity.

Yes. I think Born rigidity is more applicable, as per your link: 'The mathematical treatment of this paradox is similar to the treatment of Born rigid motion. However, rather than ask about the separation of spaceships with the same acceleration in an inertial frame, the problem of Born rigid motion asks, "What acceleration profile is required by the second spaceship so that the distance between the spaceships remains constant in their proper frame?"' I think that I didn't know enough about what I was talking about in post #1 to even ask the right question. For example, what measure of distance are we talking about when saying that it "appears constant"? I think it would make sense to ask something like, is it possible to keep a ship at 1 lightsecond away, such that the time of any return signal from the observer to the ship is always 2 seconds (ie. using radar distance). Suppose we have the observer sending out signals, and it does the instantaneous acceleration, and then continues sending out the signals. Then the question could be rephrased: say we place mirrors at various points, one for each signal sent, so that it is returned to ship with a return-trip time of 2 seconds; is it possible for a single ship to pass through each of those points at the time the signal is reflected, such that a single mirror could be used? But if "same distance" refers to the instantaneous distance given by the Lorentz transformation, that's a different question. Edit: I think Bell's paradox and Born rigidity refer to lengths as given by the Lorentz transformation. If the question is asking about radar distance, I think the answer might be easier... I think that as long as the observed ship *appears* synchronized with the observer, both the distance and Doppler shift can *appear* constant ...... but the more I think about it, the less certain I am.

I think that the assumption of standard simultaneity in SR is unnecessary, and that apparent simultaneity works just as well, and improves SR. It is explained here: http://vixra.org/abs/1304.0023 Abstract: We consider a model of special relativity in which standard simultaneity is replaced by an alternative defined per observer by the direct appearance of simultaneity. The postulates of special relativity are interpreted to permit it, using a corresponding measure of distance chosen so that the measurement of lights speed remains invariant with a value of c. The relativistic Doppler effect and Lorentz transformation of time are derived from direct observations without consideration of a delay of light. Correspondence of the model with SR is further shown by finding a displaced observer whose measure of apparent simultaneity is identical to a given observers measure of standard simultaneity. The advantages of apparent simultaneity include unifying apparent delay of light with relative simultaneity, and unifying changes to relative simultaneity with change in observer position. With speculative interpretation the model implies an equivalence of time and distance. Any comments or advice on the paper would be appreciated.

Unless their timing and acceleration is set up to exactly counteract length contraction from their relative velocity, which is the condition of "Born rigidity."

"Where" refers to locations within a space. Locations in a 2d space representation of the universe don't have to relate to those in another 3d (or 4d) space. The 2d space can be separate, so there need not be a "where" in 3d space it can be found. For example, higher dimensions don't need to be located somewhere in 3d space. Still, locations in the 2 different spaces *can* relate. If the new stuff is still the same as the last time I read about this, then it's possible that all locations in the 3d space map to all locations on the 2d surface and vice versa. This is part of the holographic principle, I think... and it is like a hologram: Every part of a 2d hologram contains information from all over the 3d image it represents. You can see the different parts of a 3d image by looking at the same 2d location from different angles. Conversely, you can fix your eyes on a single point in the 3d image, and see it by looking at different parts of the 2d image from different angles. So essentially, a location on the 2d surface is "everywhere" in the 3d universe, and vice versa. The geometry of reality is defined by measurements in our 3d (or 4d if you want) universe. I don't think anyone will try to redefine reality just because it turns out to be emergent from some different underlying fundamental physical entity or whatever. But who knows. It should be possible to define measurements and locations in a 3d universe, and some other set of measurements of a 2d universe. Then I imagine you'd have different concepts of "where" that apply to the respective spaces. Since they both represent the same universe, it's reasonable to expect a mapping between locations of the two.

Born rigidity seems applicable. The original question might be expressed as "what happens if a Born rigid system stops accelerating and comes to relative rest?" In that case I think the timing could be set up so that one observer sees the length remaining constant, but both observers couldn't. I think this agrees with what J.C.MacSwell wrote. The two observers couldn't remain in sync, as described in the link: "although the proper distances with respect to the instantaneously co-moving reference frames remain constant, the proper times of the different parts of the object do not remain coherent. In other words, if we contrive to hold the spatial relations fixed during an acceleration, a phase shift is introduced between different parts of the object, just as, if the phase is held constant, there is spatial stretching." Edit: But then, according to the main observer, the other suddenly goes from having a relative velocity to being at relative rest. I don't know how the change in length contraction and relative simultaneity would appear or if it could be compensated for. There must be a simpler and more interesting way to look at this question.

No, this is not the right way to look at it. Spacetime isn't some thing that is created in imagination and then described. Nor is it something that is confined to the realm of math. Spacetime, and what it means to be curved, has a specific definition. It is defined not based on what exists, but based on what is observed. The reason that it is not just a mathematical device is that it can be measured. Experimental measurements agree with the math. Somehow you're treating it both as an entity and as physically baseless, when really it's neither. Just because it is defined and measurable, doesn't mean it exists as a thing, only that it is a useful model.

Maybe there's an optical switch that's blocked, or a contact switch that's bent or jammed open, so it's detecting paper? Or perhaps loose belt, or jammed axle or something like that, so it's detecting having a hard time moving the paper?

The name refers to a cracked skull and is an insult. If you call a person's ideas "crackpot" I don't think it's an attack, but if you're talking about the person because of their ideas, it is. Crackpot's come to mean "An eccentric person, especially one with bizarre ideas," and "bizarre" includes stuff outside of mainstream. I don't think that's insulting alone, however it can depend on the context. Cranks are sometimes called crackpots, but I think of them differently, a crank being one who promotes crackpot ideas zealously and obsessively. A dreamer or far-outside-the-box thinker fits the modern definition of crackpot so I think it's possible the word can be used without intending an attack.

I missed the post where the thread was officially redefined. No one claimed that the local speed of light is slowed, only the coordinate speed. Why make false accusations? Let's get back on topic of JVNY's question.

I thought everyone agreed that that claim was speaking of the coordinate speed of light. That's why you must consider length contraction.

Don't forget about length contraction.

No. There's no known way to cause a specific effect on one particle that can cause a corresponding effect at the other, ie. no way to put information into one particle that can be detected using the other particle alone. Sharing some information does not require communication. I read about this at http://www.mit.edu/newsoffice/2013/you-cant-get-entangled-without-a-wormhole-1205.html, which speaks of the particles "communicating" (in quotes). This is exactly the type of story that pop sci writers screw up, miseducating people. The video in this post--- http://www.scienceforums.net/topic/663-spotting-pseudoscience/page-8#entry781154 ---expresses how I feel better than I can!

I think the argument is flawed. On one hand, God might not exist. That's not so bad because you can start with "Assuming God exists, ..." but that's such a big assumption that it's hard to draw useful conclusions. On the other hand, a god might be able to create unimaginable things, that are greater in any number of ways than any example you bring up. It would be like saying "da Vinci couldn't create the exact paint spill I made while I was distracted eating glue". True but meaningless. However, even assuming that God exists and is not infinite, there's nothing in your argument that contradicts the idea that god created "Ring of Fire" and directly evoked Cash's rendition of it, let alone the possibility that it could if it wanted to. Or foresee it before Cash existed, or foresee every possibility whether or not it exists, etc. To help prove the point, Cash didn't write Ring of Fire. June Carter and Merle Kilgore did. So how can you possibly argue that only Cash could ever think of it?

Yes, the math always works out. There's no issue there with SR's predictions, only with how they're interpreted. I don't even see an issue with interpretation, because the back-and-forth change in simultaneity has no real lasting and measurable effect. The "current time on Earth according to the traveler" is just a relation, without any causal connection between "now" for the traveler and the changeable "now" on Earth. The actions of the distant twin doesn't "cause" clock advancement and regression on Earth, it just determines the twin's current relationship with Earth time. Your example is like the Andromeda "paradox": http://en.wikipedia.org/wiki/Rietdijk–Putnam_argument (Though after reading it, the Andromeda "paradox" seems more philosophical and less interesting.)

It resonates with me because it adds additional details that can help to figure out what's going on. It is interesting to consider that an experiment can be made symmetrical just by adding stuff to mirror anything asymmetrical. However it doesn't change the "paradox", because while A and B are symmetrical, and A' and B' are symmetrical, the original asymmetry between A and B+B' remains. But that's the accepted interpretation if or while the clocks are moving inertially. What is the case when there's constant acceleration (but no gravity) like in post #391? Is it right to say that the other observer's clock is always running at a slower or equal rate, but the continuous change in velocity corresponds to a continuous change in simultaneity that can have the remote clock advance beyond a local clock? Or is it right to say that since time dilation refers to the actual difference of elapsed time, and the effects of the continuous change to simultaneity can't be separated out, there's no sense in saying the remote clock ever ticks slower when it is always effectively ticking at an advanced rate?

Thanks. I think my point in the non-bold text was something like... Assume B and C pass at an event (a definite location and time). At that moment, with B and C both remaining inertial, they predict/calculate different relative simultaneity with A (even though A appears the same to both at the time). With the example values (gamma=2, B and C are 1 travel year away from A at their meeting), B calculates that A is 3 years younger than C does. Now, if you imagine B turning around to travel with C, there is a change in relative simultaneity that corresponds to B now agreeing with C's determination of simultaneity. If one tries to assert that the turn-around "causes" a differential aging in A corresponding to that change in simultaneity, it requires cumbersome interpretation I think, because that aging at A has already occurred according to C, whether B turns around or not. Nobody's turn-around or acceleration has caused what C measures. The importance of acceleration in this example, is that it determines whether B agrees with C by switching to its inertial frame. (On the other hand, if B doesn't turn around then B doesn't measure any twin paradox effect itself. So while I think it's okay to say B's acceleration doesn't cause any physical advanced aging at A, its own determination of what happens depends on its own path and thus on its own acceleration.)