Re: About absolute reference frame......

Tom Roberts wrote:
socratus wrote:

1 Ptolemee considered, that reference frame connected with the Earth
is absolute.
2. Copernicus proved, that reference frame connected with the Sun
is absolute.
3. Then they began to consider, that reference frame connected with far
stars is absolute.
4. Now it is consider, that reference frame connected with relict
isotropic radiation T = 2,7K is absolute.


Your use of "proved" is too strong. "assumed" would be much more accurate.

Note also that the word "absolute" has many connotations, many of which do not really hold here.

In modern physics, all of our fundamental theories obey the Principle of Relativity, which says that the local laws of physics do not depend on which locally-inertial frame one references them to. That means there is no "absolute frame" in modern physics, for suitable meanings of "absolute". I put it in quotes, because these phrases have such nebulous and variable meanings that one must be careful in interpreting them.

In particular, the CMBR dipole=0 frame is "absolute" in the sense that at the location of earth it is a specific locally-inertial frame. But it is not "absolute" in the sense that the laws of physics are any different in it than in other locally-inertial frames (this was the meaning of "absolute" in ~century old aether theories, among others; all have been soundly refuted by experiments).

[My first post was pretty unclear in some places, so here is an updated version.]

Well, Lorentz believed that light did, in fact, travel at a constant velocity relative to "the ether," or as we would say today, the medium of space, but he also showed that an experiment's initial velocity would not affect the results, so it's not entirely fair or accurate to say that they believed that "the laws of physics were different," without distinguishing between "some of the laws of nature are 'absolute laws,' i.e., functions of absolute velocity" -- their belief, and one which is, for all we know, quite true -- and the idea that those laws were *observably* different in the sense that they would change the outcome of an experiment. After all, the principle of relativity will be correct if there are no absolute laws, true, but it will also be correct if there are absolute laws, but (1) experiments contain either two or more absolute laws, or no absolute laws at all, and (2) when an absolute law exists in an experiment, its effect on the results is always exactly canceled out by the effects from one or more other absolute laws.

The modern objection to absolute laws is more of a philosophical objection, rather than one which necessarily follows from experiments. Remember, if an experiment is stopped, its absolute velocity changed, and then resumed, the results often change (the standard clock paradox is an example, as are most experiments that measure the speed of light). If the *only* thing that has changed is the experiment's absolute velocity, then that change, alone, is the *only* thing that can have affected the results, which means that *something* must exist that is a function of absolute velocity.

This is easier for us humans to see and understand when using position, rather than velocity. Running an experiment for a while, stopping it, changing its position, and then resuming it, can affect the results if and only if some of the characteristics that affect the results *vary* as a function of position. If nothing varies as a function of position, then changing the position, alone, cannot possibly affect the results.

Similarly, if no laws existed that were functions of absolute velocity, then changing an experiment's absolute velocity and nothing else while it was temporarily stopped could not possibly change the results. In contrast, experiments which are at least assumed to fall under the laws of Newtonian mechanics can be stopped, their absolute velocity changed, and then resumed *thousands* of times during the experiment with no effect whatsoever on the results (since the laws controlling the results are not functions of absolute velocity, only absolute acceleration).

A more realistic view of things would be to state that "Nature 'permits' our experiments to reveal only that information about our absolute velocity that we could deduce on our own, before running the experiments." If our absolute velocity *changes* by 0.5c, and the results depend in part on some characteristic that *varies* as a function of absolute velocity, then we can deduce beforehand that the results will be affected accordingly, and the results will indeed confirm our predictions. However, we cannot distinguish beforehand between a change from 0 to 0.5c, or from 0.5 to 0.8c -- both of which *appear* to be a change of 0.5c relative to our *initial* absolute velocity -- and in fact the results will also tell us nothing about our initial velocity. Changes in the results of experiments caused by changes in absolute velocity during the experiment (even if it is stopped, meaning that acceleration plays no part), or by having a minimum absolute velocity relative to some inertial observer -- simple geometry forces an "out and back" observer like the traveling observer in the clock paradox to have an average absolute velocity that is at least as great as that seen by the local observers -- do occur, something that would be quite impossible if there really was no such thing as an absolute law.


That frame is no more
"absolute" than is the locally-inertial frame in which the sun is at rest. Or my little finger.


And if has the scientific idea stopped in this point?
What is farther?


I don't know what you are trying to ask. While current theories of physics have no "absolute frame", there just might be future theories which do so, but they necessarily must be constructed so it is exceedingly difficult to detect the "absolute frame", because of the absence of such detection in current experiments[#]. These possible future theories are related to quantum gravity....

[#] There are some people around here who claim that some
experiments have detected an "absolute frame", or the
"absolute motion of the earth", or somesuch. They are
wrong, and basically don't understand what experimental
physics is.

Actually, there is one experiment (that I am aware of) that truly violates the principle of relativity, but it would be really hard to do, and take a really long time. Physicists believe that if you travel in a straight line long enough (as in, follow a beam of light), you will eventually return to your starting point. In theory, therefore, we could send out radar pulses (or the output from a supernova, whatever) in all directions, and they also would eventually return to their starting point. Assume that observer A does so, and that everything returns in 10 billion years (as a side note, I know of nothing in GR that says that this could not possibly occur, at least in a "GR-legitimate thought experiment," but if you know differently, please let me know, as I plan to incorporate this in a paper). If observer B moves 1 million light-years "to the right," and then synchronizes his clocks with A, both A and B will expect one radar pulse to reach B 1 million years before it reaches A, and another pulse to reach B 1 million years after it reaches A; a perfectly normal and expected result under GR. However, if inertial observer C just happens to be next to A when the radar pulses are sent out, and just happens to have a velocity that will put him next to B when the first radar pulse reaches B, then NO ONE (except C) will expect all the radar pulses to return to C simultaneously, and in fact, C can use the difference in return times, plus the total time, to deduce his absolute velocity. Now, both A and C are inertial observers, and they *should* have the same results, but they won't, even if it is C who sends out the radar pulses when he is next to A, nor will A *predict* that C will have the same results, although that also is a violation of the principle of relativity (observers should both predict and see that experiments by others have the same results as the observers own experiments). Of course, if light traveled at a constant velocity, c, relative to the *source*, then if C sent out the radar pulses, he would see himself as motionless, but this has been proven false by the observations of binary stars, and is in fact contrary to Einstein's second postulate (as an interesting side note, the second postulate cannot simply state that "the measured value of c is the same for all observers" -- that would not tell us whether time slows down, mass increases, etc. -- but must *specifically* state, either directly or indirectly (as was done by Einstein), whether c is an absolute law).

I posted this in a much less clear form a few years ago, and got either rabidly stupid and/or defensive responses (here; e.g., "How can you travel around the universe by moving in a straight line?"), or dead silence, not one response (s.p.research). All I ask is that you do not tell me, as one idiot did, that the lack of responses was due to "polite silence," since all other would-be exceptions to the principle of relativity get responses, and they make WAY less sense than this one!

Phil

P.S. To email me off-list, remove my head.


Tom Roberts tjroberts@xxxxxxxxxx
.

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