Stop muti-posting! Please edit post 12 to include the ones after it and delete the others.
A-wal said: "The astronauts didn't leave their bodies so they themselves didn't go anywhere, from their perspective Earth moved away from and the moon moved towards them. Of course they accelerated to leave the Earth and the had to overpower the gravitational acceleration of the planet to do that but during the journey when they weren't accelerating, the moon was moving towards them every bit as much as they were moving towards it because there's no distinction between the two."
You seem to find it impossible to distinguish fictitious theoretical mathematical/philosopical claims from practical reality, A-wal.
You say "from their perspective," but that's absurd. What you really mean is "from MY perspective, which I impute to them and demand that they adopt and adhere to."
No when I specify a perspective I'm referring to the objective reality of what an observer would experience in that particular frame of reference, regardless of whether or not that observer has the intelligence to understand why they experience what they do.
No astronaut who went into outer space EVER, from "their perspective," thought they were motionless while the earth moved away from and the moon moved toward them. EVER! They know better, as a practical matter, and would (properly) reject and resist your attempt to impute a different "perspective" to them just so you can claim the math model of SR is true as a matter of empirical fact (which it aint).
Astronauts tend to be well versed in physics so I'm sure they'd be perfectly aware that while they're in inertial motion they are free to view themselves as motionless and other objects as in motion relative to them.
They wouldn't deny all other physical principles to maintain this philosophical fiction. You concede that "of course they accelerated to leave the Earth and the had to overpower the gravitational acceleration of the planet." And what does Newton's law of inertia (which SR accepts) say about that? That a body in motion will stay in motion unless acted upon by an external force, right?
Yet YOU want to say that the instant they stop accelerating and settle into maintaining a uniform speed, then they INSTANTLY STOP ON A DIME and become motionless. At that moment THEY are suddenly motionless without any explanation of how that is possible (which it aint). Normal people don't ignore the known laws of physics like that--at least not to the point of claiming that's what's actually happening as opposed to saying it just a complete, yet presumably useful, theoretical fiction to pretend that it's true.
They would also understand that this in no way violates any other established physical principles. Once an object stops accelerating it's an inertial object and whether or not it's motion is a purely arbitrary choice of coordinate system. Motion only makes sense if it's motion relative to another object and once an object stops accelerating to say it can't be viewed as being at rest makes no sense. From the perspective of an object that was already in the frame of reference that the accelerator ends up in (so at rest relative to the accelerator once they've stop accelerating) the accelerator was in motion before accelerating and then decelerated to become motionless relative to them. There's no distinction between acceleration and deceleration, deceleration is just acceleration viewed from a different perspective.
No astronaut has ever taken the "perspective" you impute to them, and none ever will. You couldn't ever even become an astronaut if you were that oblivious to physics. Astronauts aint stupid.
If the astronauts on their way to the moon judge their velocity by using the moon's frame of reference so they are in motion then it's a valid way to look at it but no more valid than using any other frame of reference. If you think it is then you need to learn to think better. What would happen if the astronauts thought 'let's not go to the moon, tis a silly place. Let's go to Mars instead.' Now they're heading towards Mars but the moon is at rest and you think that's a preferred frame but if they're heading towards Mars then that would have to be a preferred frame, so their frame of reference would have to depend on their object of destination? Do you see how silly that is?
What if Earth, the moon and Mars were in alignment when they decide to go to Mars instead so they didn't even have to change direction, now their 'absolute motion' through space changes based on their decision about which celestial body they'd like to visit. If you think the sun should be used as a basis for absolute motion then what if they decide to visit another star system (they're in the future now)? At would point during the journey would their absolute motion depend on the destination star?
A-wal said: "This only applies to inertial frames of reference. The frame of reference of an accelerating observer is outside of the frame work of what this model describes...The speed of light isn't constant in accelerating frames, it's always slower."
Exactly, which is just one of many reasons why a theory of relative motion which incorporates absolute simultaneity (such as the RMS model) is vastly superior to SR and is used in the GPS while SR is rejected (because it would give inaccurate and contradictory predictions).
With accelerating objects, there is no pretense to "reciprocal time dilation," etc. It is explicitly acknowledged that the clock of an accelerating object runs slower and that the clocks of (relatively) inertial objects run FASTER, NOT SLOWER. This is an ABSOLUTE phenomenon, not a relative one, as even all SR adherents admit.
An AST (absolute simultaneity theory) makes perfectly accurate predictions for ALL moving objects, not just the that extreme minority of objects (if there really are any at all) that are not accelerating.
There can never be absolute simultaneity. It's very easy to show that events that one observer views as simultaneous can't be simultaneous from the perspective of an observer that's in motion relative to the first observer.
A-wal: "There is an inertial frame everywhere in the universe because motion can't be detected."
Yes, I agree that SR does make this claim, but it's absolutely absurd, nonetheless.
SR merely mimics an AST by postulating a preferred, absolutely motionless, frame for every calculation it makes. According to SR, the preferred frame is always the one YOU are in (if you are inertial). Any and every thing in the entire universe which is moving with respect to YOU is moving. YOU are absolutely motionless. Every observer is a motionless luminous ether unto himself, per the mandates of SR, and there are an infinite number of motionless frames. Problem is, as a practical and possible matter, only one frame can be motionless, never more than one when there is relative motion between them. As I said, the whole notion is ridiculous.
No that's not what the term preferred means in this context. A preferred frame of reference is one in which the laws are different. No such inertial frame exists. Sr doesn't require that every inertial object is at rest in their own frame, it's an arbitrary choice, any inertial observer is free to use any frame of reference in which they are in motion because all inertial frames are equivalent. What's ridiculous is thinking you know better than a model that you can't even understand.
Awal said: "If one twin were to leave Earth and accelerate just the once so they were moving away at a constant velocity and the other twin left Earth later on to catch up and then accelerate into the frame of reference first twin to leave once the second twin catches up then it would be the second twin that left Earth who would be younger."
Yes, of course. But this is not caused by a change is some fictitious "frame of reference," which exists only as a mental construct. It is because the accelerated twin is the one ACTUALLY MOVING and it is the moving clock which ALWAYS runs slow. For whatever reasons, increased speed actually causes clocks (and all physical precesses) to slow down
The circumstances are NOT symmetrical, needless to say. Relative to each other, one is moving (faster), one is not.
You've completely misunderstood, just as you've misunderstood everything else. These are your failures to understand a logically consistent and verified model of reality, not failures of the model. Frames of reference are certainly not mental constructs and neither twin is 'actually moving', they are in motion relative to each other and to say one is moving and one isn't or one is moving faster than the other doesn't make any kind of sense, all inertial motion is relative. It may be nicer for you to think you are capable of understanding this that you can't make sense of the model because the model itself doesn't make sense but I assure you this isn't the case.
A-wal said: "Completely wrong on both counts. All the data empirically proves that the speed of light is constant and therefore that time dilation and length contraction are a fact because it's logically impossible for them not to be."
Wrong. As I have noted in another thread, the speed of light is NOT constant in every frame, and logically in can't be.
I'm afraid it can, and it has been shown that it is. The fact that you think it's logically inconsistent proves that you simply can't grasp the model because a constant speed of light is definitely not logically inconsistent.
It is, however, always MEASURED to be the same. But that's not because it IS the same. It's because speed distorts the measuring instruments which are used to calculate and determine the speed of light (time and distance). That distortion is exactly what the LT "correct for.'
Oh dear, you're having having trouble aren't you. This 'distortion' as you put it is the time dilation and length contraction that allows the speed of light to be measured as the same in all inertial (and entirely equivalent because none are more valid than any other) frame of reference.
If it is claimed that one object is "moving faster" than another, then it is legitimate and natural to ask: "Compared to what?" AST theories give accurate predictions ONLY when ALL motion is calculated by reference to the center of the dominant gravitational field of the locality where the prediction is made. As Einstein said: "All physics are local."
For calculations involving the speeds of various objects in motion on or near earth, this would be the ECI, as used in the GPS. For measurements on a solar scale, it is the barycenter, which even the Sun revolves around. Compared to anything else in the solar system, the barycenter is indeed the only point which is not "moving." Newton, Keppler, Copernicus, et al, used this point to calculate the speed and direction of planetary orbits--using the background of the "fixed stars" as a "close approximation" to another "motionless" frame.
For the Milky Way, the black hole at the center of the galaxy's mass is used. For "universal" measurements, the CMB has been used by astrophysicists as the preferred frame of reference for many decades now. For practical purposes, all such local frames of reference can be treated as "motionless" for local experiments in order to achieve accurate predictions, even if they are not "truly motionless" in the overall scheme of things.. Reference to the CMB tells us, for example, that the entire MIlky Way is moving at a high rate of speed toward the "great attractor." But since that motion is common to every object in the Milky Way, it can be ignored when making intra-galactical calculations of relative motion.
Of course all such calculations are prohibited by SR, which (purportedly, at least) forbids the use of a preferred frame. But that does not make their use less accurate--it merely exposes how inaccurate predictions based on the strictly relative motion relied on by SR can be.
The frame in which the CMB is at rest is in no way a preferred frame of reference and nobody but you is claiming that it is. You're free to use any inertial frame in which the CMB is in motion and it changes nothing because all inertial frame are equivalent.
Your constant ignorance is very tiresome. You're unable to come up with any kind of coherent argument to support your ridiculous claims, all you can do is demonstrate all the ways in which you're unable to understand the model but guess what, you don't need to understand it. Being understood by people that are incapable of grasping even the basics is not a requirement for an accurate model.