Why in the world would Einstein suggest....

@FBM,

Quote:

Let me tweak my statement for clarity: I'm not sure that the physics of the particular experiment in progress would be affected if...

Well, the physics would be--i.e., how we would interpret any given experiment, I mean. The mathematical calculations might give you the same raw answer, as to speed difference, etc., but that not what "experiments" are about, really.

The fundamental ontological implications vary vastly. Whether we live is some mysterious 4-dimensional world were "time itself" (as opposed to clocks) and "space itself" (as opposed to yardsticks) change with speed, etc.

Not to mention the absolutely subjectivist "philosophy" (metaphysics) which SR presupposed and foments.

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@layman,

layman wrote:

Quote:
SR tells us that there's no absolute frame of reference.

Well, this is another common misconception, I think. SR does NOT say that. ...

Quote:

The two famous postulates of special relativity are (1) the principle of relativity: there is no
absolute rest frame of reference and (2) the universal speed of light: the speed of light is
constant in all inertial frames of reference (Griffiths 1989:449).

http://vixra.org/pdf/1212.0043v4.pdf

Judging from the abstract, that paper might make an interesting read, by the way. You might be able to use it.

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@FBM,

Quote:

...there is no absolute rest frame of reference

Not really an uncommon misstatement, probably. One need only go back to Al's original 1905 paper to see how he actually stated his postulates. And, for that matter, I just posted excerpts from an Harvard physics professor who re-states the postulates (that ain't one of them).

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@FBM,

Quote:

Judging from the abstract, that paper might make an interesting read, by the way. You might be able to use it.

Yeah, it's looks like something I'd be interested in reading (although that doesn't mean I'd agree with it). I'll read it later.

But I note that the abstract itself does NOT say that is one of the postulates. It says:

Quote:

This paper analyzes how special relativity derives the time dilation, and then explains how it leads to a disagreement on the first postulate: the principle of relativity. Next, this paper continues to explain a disagreement on the second postulate: the universal speed of light.

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Not sure if this is an exact quote from his original paper:

Quote:

On June 30, 1905 Einstein formulated the two postulates of special relativity:
1. The Principle of Relativity
The laws of physics are the same in all inertial frames of reference.
...

http://www.nobelprize.org/educational/physics/relativity/postulates-1.html

An absolute inertial frame of reference would seem to require different laws of physics. Otherwise, it would be indistinguishable from non-absolute frames and therefore not absolute at all.

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@FBM,

Quote:

An absolute inertial frame of reference would seem to require different laws of physics. Otherwise, it would be indistinguishable from non-absolute frames and therefore not absolute at all.

I agree. But SR posits that ALL inertial frames are equivalent (which would necessarily INCLUDE an absolutely motionless frame), so it, by definition, would not be able to detect it.

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@layman,

A motionless inertial frame is an oxymoron. Wink

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@FBM,

Quote:

A motionless inertial frame is an oxymoron

Why would you say that? An inertial frame is one that is either (1) at rest, or (2) maintaining a uniform velocity

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@layman,

Because Wiki told me so. Wink

Of course, the Wiki could be wrong, but that is literally why I wrote that.

Quote:

All inertial frames are in a state of constant, rectilinear motion with respect to one another; an accelerometer moving with any of them would detect zero acceleration.

http://en.wikipedia.org/wiki/Inertial_frame_of_reference

1 Reply

@FBM,

I'm reading a little bit of this paper you cited. OMG, this guy is questioning the validity of the classic and sacrosanct "light clock" line of reasoning:

Quote:

To reiterate, the electromagnetic wave radiates from the retarded position of the moving source, not from the current position. Thus the light could not have moved along with the train after it has been emitted from the moving light source.

Next thing you know, cats will be sleeping with dogs.

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Looks like Wiki let me down again:

Quote:

An inertial frame of reference has a constant velocity. That is, it is moving at a constant speed in a straight line, or it is standing still. Understand that when something is standing still, it has a constant velocity. Its velocity is constantly zero meters per second.

http://zonalandeducation.com/mstm/physics/mechanics/framesOfReference/inertialFrame.html

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@FBM,

Quote:

All inertial frames are in a state of constant, rectilinear motion with respect to one another; an accelerometer moving with any of them would detect zero acceleration.

You're reading a little too much in to that. "Zero acceleration" is just another way of saying "inertial" (non-accelerating). And two such frames would, therefore, necessarily, not be accelerating "with respect to each other."

Quote:

.. in an inertial frame, the center of mass of a system of bodies is always at rest or in uniform motion. It also follows that any other frame of reference moving uniformly relative to an inertial frame is also an inertial frame.

http://plato.stanford.edu/entries/spacetime-iframes/

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@layman,

I'm not sure what you think I'm reading into that.

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@FBM,

Quote:

I'm not sure what you think I'm reading into that

I added a different site to my post---you seem to be reading into it that a inertial frame MUST be in motion.

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@layman,

I wasn't reading anything into it. I explained that I screwed up by just checking the Wiki instead of a more dependable definition. The Wiki says that inertial frames are always in rectilinear motion...wait...with respect to each other. So that means one could be stationary while the other is in motion, and due to relativity, it would be meaningless to declare which was in motion and which was stationary. I think we've come full circle. Damn. I going to scroll up and re-read a bit. I think I'm missing something.

Edit:

Seems to me that if you have two inertial frames, you could always solve the problem (time dilation or whatever you're looking at) while treating one of them as if it were at rest. Then you could do it with the other one and get the same answer.

So we still don't have an absolute inertial frame of reference, as far as I can tell.

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@layman,

Quote:

I added a different site to my post---you seem to be reading into it that a inertial frame MUST be in motion.

Not surprising, the way wiki puts it. Whoever wrote that article seems to have made certain assumptions about motion (under the influence of SR) and implicitly included them in the definition. However, Al made it clear that he was retaining Newton's definition of inertial motion intact, and, as you no doubt recall, Newton said, more or less: A body at rest and a body in uniform rectilinear motion will maintain their state of motion (which includes NO MOTION) unless acted upon...

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@FBM,

Quote:

I added a different site to my post---you seem to be reading into it that a inertial frame MUST be in motion.

Yeah, I acknowledged that the mistake was not yours (I added to my original post).

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@layman,

Quick non-SR related question: Do you want an absolute inertial frame? If so, why?

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@FBM,

Quote:

I think I'm missing something.

No, I don't think you're missing anything now.

So that means one could be stationary while the other is in motion

Right, that's why I said you were reading too much into it---but you were misled to kinda assume that by the relativist who wrote the article.

Quote:

So we still don't have an absolute inertial frame of reference, as far as I can tell.

No, we don't. So far we've just got off on a tangent as to whether or not SR says there CAN'T be one.

1 Reply

@layman,

Digressions can be useful to the noob, but often at the cost of being tedious to the adept. Smile

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Why in the world would Einstein suggest....

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