Sir Chronos, your responses show little if any thought.
Chronos said:
How do you define 'rate'? All definitions I am aware of include the variable 'time'. Please explain how a 'serious discussion of time' excludes time.
We cannot have a serious discussion of anything without first defining what it is we are talking about. The issue of this thread is a concise and well thought out definition of "time". One of the first issues of definition itself is that the word being defined is not to be used in the definition. A definition which includes the word "rate" requires a definition of "rate" before it is useable. Since "rate" is generally defined as the ratio between change in something and the change in time, the concept presumes time is defined and thus is not a valid concept within the definition of time.
Chronos said:
I would say he is still missing some subtle issues!
Chronos said:
Because 4Newton was wrong. The issue is settled until new evidence is introduced to refute it. The 'best proven' explanation must be preferred over the 'best unproven' explanation.
It appears to me that you have a lot of confidence in what has and what has not been proven. I think it would benefit you to take a little trouble to think about these things.
Chronos said:
That makes no sense. There is no 'modern analysis of relativity' that disagrees with conventional relativity.
Now I would contend that is a rather extreme statement. They certainly disagree as to the proper equations to be used to transform from one coordinate system to another. You should be more careful in your pronouncements.
Chronos said:
Agreed, SR does not include gravity.
Neither did Newtonian relativity! What is much more significant is that SR does not include a rule for transforming between accelerating coordinate systems which Newtonian relativity does. It was Einstein's attempts to generalize his theory (an absolute necessity by the way) which lead to the gravitational results. If you look at the fundamental deduction of general relativity, you will find discussion of direct transformations from a coordinate system attached to an accelerating elevator. Problems in measurement arose there which did not allow a simple generalization thus Einstien's result was not unique. A very interesting problem which has received little really serious attention.
Chronos said:
There is no evidence a 'natural unique coordinate system' exists. There is, however, enormous evidence it does not exist.
Now here you are fighting a losing battle as "natural unique coordinate systems" are use all the time on a day to day basis in physics. In fact, lots of different "natural unique coordinate systems" are used. For example, the rest frame of the laboratory in which an experiment is done; or a coordinate system which makes the one way speed of light the same in all directions.
The central issue of relativity is that all these coordinate systems are equally valid. In almost every case, each and every experiment suggests it's own "natural unique coordinate system". It is the fact that the "laws of physics" must be the same in all of these coordinate systems which allows us to determine the required transformation equations between those various coordinate systems.
And finally, to Russ, I still say you are being a bit provincial with your comments. I think it would be worth your while to step back once and look at the fundamental nature of the problems which confront us.
russ_watters said:
The CMB does indeed allow us to measure a speed with respect to it - however, that speed is not needed to make any of the calculations 4Newton was proposing. Therefore, its not a universal reference frame.
I would expect a mentor to take a little more care with his comments. What you say cannot possibly be rationally defended as logical.
You are saying that because "that speed is not needed to make any of the calculations 4Newton was proposing", it is not a universal reference frame.
You seem not to understand the principle of relativity. The principal or relativity is that all reference frames capable of indicating the information associated with any given experiment are fully useable. If one adds to that the fact that the laws of physics are particularly simple in a specific frame (think of Newton's inertial frame), then all one needs is the specific transformation from the particular simple frame to a frame of reference of interest and one knows what happens in that frame of interest. Einstein's General Relativistic frame is just such a "simple" frame, quite analogous to Newton's inertial frame; however, the required transformations to the frames of interest are not quite as simple as Newton's but they can nonetheless be done.
That fact is used over and over again throughout physics. There are a number of unique frames used all the time. For example, the GPS system is a coordinate system tied to time as measured by a clock in Colorado and is by that fact, a very unique coordinate system. Since it is always possible to set up a specific coordinate system tied to a specific clock the term "universal" could be attached to the concept.
There is another rather unique coordinate system used quite often in a lot of experiments. That would be a coordinate system tied to center of mass of the universe (in this case, read "universe" to be a reference to the collection of entities which are significant to the experiment of interest and may range from no more than the components of a single nucleus to a nuclear accelerator, the solar system, the galaxy or everything including the cosmic background). Call such a coordinate system a CoM system. Certainly the CoM system is unique and it is also quite universal. One can very reasonably suggest that relativity should require the laws of physics to be the same in every CoM system conceivable.
In fact, that is essentially exactly what the COBE scientists did when they documented the solar systems velocity through the universe at 371 km/sec.
But all this is outside the discussion on this thread which is "what is the definition of time?"
Have fun -- Dick