Originally posted by wimms
After you compensate for relativistic Dopler effect, what other time dilation is left?
You didn't say
Relativistic Doppler effect, you said "Doppler effect". Relativistic Doppler effect is Doppler effect corrected with Relativistic effects. In most discussions of Relativity, you usually assume that the Doppler effect has been compensated for and you only need to deal with the Relativistic transformations.
Problem is that one is forced to mix "what happens really" with "from their perspective", or more precisely, that there is NO "what happens really" at all and questions as such are banned.
While in essence it is as simple as that:
- one twin travels,
- when he returns, he aged less. Period.
Fact: time retarded for traveling twin. This is "real". On this Earth at least.
Reality is what we measure. Relativity effects how we measure. Each astronaut measures different time rates for the other. Neither measured reality has preference over the other, and neither is more real than the other. The end result is the same, but the reasons are different. So no, you can't say that one set of reasons is more real than the other.
All those details about at which point who 'thinks' what other's time does is irrelevant in comparison to this simple fact. From instant when twin leaves Earth and upto instant when he returns, there has to be definite period where his time retarded relative to earth. And it works one way only. Twin can't come back older. And this retardation is definitely as real as it can get.
Again, the age difference at the end is real, but does not mean that time redardation for one twin is the only "real" answer for this outcome.
Acceleration. Saying that time retardation of Earth is not any less 'real' than that of twin traveling is pure bs.
No,it is Relativity.
No actions of twin ship can influence timeflow on earth. Thus any effects of SR must be coupled to traveling twin. How they both detect or how they even are capable of detecting what happens on other ship is completely other issue. Fact of basement is: twin travels - twin ages less. Earth IS preferred reference frame, at least for accounting time.
The acceleration felt by the twin in the ship effects how he
measures the time rate on Earth. On the other side, the relative velocity between Earth and Ship effects how the Earth
measures time rate on the Ship.
Both realities are detemined by what is measured by each. And since Reality is determined by what we measure, both are "real".
We receive atom spectral lines from remote stars. But what do we know about natural timeflow rate there? We assume that clock rate of hydrogen is same as here, and based on freq shifts we derive relative velocity. We basically assume that clock rate is same everywhere, and only relative velocity causes changes to it.
No, we assume that the measurements of time rate would the same as long as both are within the same inertial frame, and realtive motion effects those measurements,
in both directions .
We assume all inertial frames equal only when we reduce their clock rate differences to equal ground. When clock rates differ, inertial frames are not equal. They have either relative motion or have different gravity potentials.
And its the clock rate that defines "their perspective".
Fine, but you keep wanting to make one perspective more preferred than the other.
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Or basically, either ship is measuring its own delirium. Neither what they each 'see' is real, only computationally consistent.
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All we can know about reality is what we can measure, so reality is what we measure. what each measures
is real.
Take it step further. When you go to next room, this is real motion. Or perhaps it isn't?
Of course I can say that time dilation of traveling twin is more real than his perspective on Earth time dilation. This is proved when they meet again.
No, all this says is that the age difference is real. It says nothing about how it got that way.
How do you imagine 'time retardation field' actually? How many assumptions do you pack there before saying that its impossible? I'd say I'm not sure at all. Do you assume that there would be no size dilation, energy change?
With a simple time redardation field, the viewpoints are not symetric. A person in the field would see things outside the field as running fast the whole time, and at the same rate difference as the outside observer see things moving in the field as moving slow. I the real twin scenerio, one twin sees, the other's time rate as moving slow the whole time, while the second twin sees the other follow a pattern of slow, very fast, slow.
It is a greater assumption that other effects such a length contraction and energy change would occur, than not.
Imagine ship, creating 2 fields, in front of it with increased clock rate, behind it, with decreased clock rate. I'd say this would be ship with "gravity-drive", and it would actually move through space.
Back by what? Just your general feeling that this should be true?
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Why are you are stuck with that 'absolute'? Noone ever said its absolute. Let put it this way: clock rate in our frame depends on our position in field potential. The value of potential is irrelevant, as we can only measure relative values here. Now, when twin travels at rel velocity, he climbs potential, he gains kinetic energy, and his real timeflow and clock rate slows, relative to where he comes from, relative to where he goes to! It doesn't matter what velocity Earth has relative to any other object in space. We can always compare only relative velocity between objects, and relative timeflow. The limit of relative speed is set by moving object's clock rate approaching zero relative to us. [/B]
Whenever you assert a preferred reference frame, you are invoking absolute motion, wheter you realize it or not.
The problem with your statements is that you fail to consider the other side of the coin concerning relative velocity.
Yes, the ship has a relative velocity wrt the Earth, but the Earth has a relative velocity wrt to the ship also, with a corresponding increase of kinetic energy, etc.
You can't say that is only the relative velocity of the ship to the Earth that counts, to do so perverts the very meaning of "relative motion".
You started this thread to ask a question about Relativity. I have tried to answer your questions, but when the answers aren't to your liking, you argue.
It seems to me that you aren't interested in what Relativity actually says, but only in perpetuating your own interpretation of it.