Saint

Clock synchronization - setting clocks to read the same time at a given instant Clock syntonization - setting clocks to the same frequency (rate), regardless of the time they display.

Geistkiesel, I think the problem is that people really need to hang onto the idea that space is "nothing". I mean, the idea that space is expanding was introduced, as far as I can tell, to explain how physical objects could be separating at FTL speeds. Now, if space is "something", especially something physical, with some mechanical properties that tie it to physical objects, things change. The whole reason that the idea of space expansion was proposed would be moot because space itself would be a physical reality (can't be separating from itself at FTL). Somehow, they'll find a way to link physical reality to something non-physical. And when they do, that non-physical "thing" will be expanding:)

How about the paradox that any frame can claim that every other frame is vibrating at a slower rate?

Please tell me the mechanism that leads to physical changes in vibration rates based soley on a frame's velocity relative to anything else. Not the equation you would use to calculate it, but the actual mechanism. I'll ask you the same paradox question that I asked Tom. In the twin paradox, does the returning twin's clock match the earth twin's clock once they meet back on earth? And swansont, what are the experiments that have proven that absolute space does not exist? We may have proven that we haven't found it, but that's something else entirely.

Tom - what I'm saying is that, if there are actual changes in the rate of vibration, then there should be a common baseline. That would provide a mechanism. Well' date=' saying that something "just is", doesn't help much, Tom. And what's is your take on the classis paradox? If one clock stays here on earth, and another takes a high-speed (close to c) trip around pluto and back, assuming they were in synch prior to the trip, would they be different after the trip? If they would be different, I'd like to hear about the mechanism you have said is not needed. If their clocks are the same, then relativity really doesn't say much other than OBSERVING other moving frames can lead to different OBSERVED rates of vibration. Basically it has no physical value. Again, does SR have any connection to a physical reality? Or what exactly do you mean by that statement? Thanks for the response.

I know swansont, it has been experimentally verified that there is neither space nor time There can be no physical (real) change in the rate of vibration for any physical object based soley on its velocity relative to some other (any other) observer. There simply is no mechanism by which it could be accomplished. It may be OBSERVED to be different from another reference frame, but basing actual physical changes on relative velocities, without a common baseline makes no sense.

I would think that, in order to take SR to its roots, you would have to give up the idea that we all move through some time dimension. That implies that there is some absolute time to be referenced. I don't even think Einstein could really talk about a time dimension. His idea of time, at least the one layed out in relativity, is based on the physical movements of a clock. He basically said that the OBSERVED rate of vibration in a frame moving relative to an observer will APPEAR slower to the observer. That's it. Nothing about moving through time, time travelling etc... From his simple definition of physical vibration rates, this whole idea of actually moving through another dimension (time) at different rates was born. If one accepts both spacial and time references (absolutes), you can achieve the same results (slowing of physical vibration based on velocity), while providing a real mechanism for the rate changes (lacking in relativity). That may be another discussion, but the idea would follow that for a high-speed frame (wrt absolute space) the rate of vibration internal to the frame would slow. Basically, it would take longer (wrt absolute time) for one vibration to occur. Once it slowed to absolute zero (wrt absolute space), fewer vibrations would have occurred on the previously moving clock than would have occurred on a stationary clock. Physical time would have slowed for that moving frame.

Let me further clarify - I don't think there is a mechanism by which "space" can pull a light beam apart. That would require some frictional force wouldn't it? I've never heard of light interacting with space in that manner.

That's why I inserted the comment about how light is not supposed to interact with "space". If it did, space would become the ellusive aether, wouldn't it?

Swansont - I think that the evidence is clearly there to support the idea that physical objects can, and do, move away from each other at speeds greater than c. At least if the doppler shift rule is to be trusted. The burden of proof should really fall on the claim that those objects are not moving "through space". Or, that space itself is expanding. At least that's my take. One thing - I don't really understand how the expansion of space itself could result in any doppler shift. It may take longer for light to reach us if it's swimming upstream, as described by Spyman, but if light isn't otherwise affected by space (that is, space is not the "aether"), it shouldn't result in any doppler shift.

But the redshift doesn't require that "space" expand, only that the galaxies are moving through space, correct? As far as redshift, or blueshift is concerned let me ask another question. Let's say a star puts out a beam of light (simplified for the example) at some frequency, let's call it X. This would mean that an stationary observer wrt the star would see X wave peaks per second. Now, when the observer moves toward the star, he will start to see more (X+) wave peaks per second. Effectively shrinking the wavelength - blueshift. The star did not start putting out a different frequency, but the observer is seeing a different frequency. He is moving throught the light beam at a higher rate, and therefore encountering more wave peaks per second. Does this not suggest that the observer is has increased his rate of travel wrt to the light beam?

Does this imply that light gets a "free ride" on the universal expansion wave, so to speak? And is there any proof that space itself is expanding, or is that simply a way of rationalizing speeds greater than c with relativity?

So no physical object in the universe is moving away from any other physical object at c? Now from a third party, can those two physical objects be seen to be moving away from one another at c?

I've got a question, and I'd start another thread, but my profile doesn't seem to want to let me do that. What does the theoretical speed limit of "c" apply to? I've seen it posted that matter cannot reach the speed of light. I'm assuming that, since we're talking relativity here, that means two frames of reference cannot move away from one another at "c", if those frames are constructed of something physical. So that means that two reference frames, however unrelated, can never move away from one another at speeds >= c? Is that right? If that's right, I have another question. What possible physical limit can be placed on the motion of an object wrt any unrelated frame of reference? Basically, how can you place a real, physical limit on something based only on the choice of reference frame? I could be way off here, but I figured I'd ask.

Probablity waves don't occur in nature. They are mental constructs.

I've read, and heard, that there is no inertial (rest frame) for light. Where does this idea come from? Did it originate simply from the statement that the speed of light is constant in all frames - therefore there cannot exist an inertial frame in which the speed of light is zero? Or is there something more to back it up?

Stating that there exists a "space" to expand suggests that light travels through that space. I have not read all the posts on this thread, but this sounds a lot like the ever ellusive aether. But once you identify that the aether exists, that is, whatever it is that is expanding, the limit on the speed of light is nullified. Einstein wouldn't like that.

Theoretically, yes there were. If you view the drag profile of a body moving toward the speed of sound, it's asymptotic. At the sound barrier it takes a steep dive. But I don't believe that was known until it was tested. There was, theoretically, sceintific data (calculations) to support the idea that the speed of sound was the physical drag limit.

OK - I'm assuming that the speed you used is referenced to a common inertial frame? If your spaceships are moving toward each other at 2x10^8 m/s as referenced to some common inertial frame, where would the measurement need to be made from in order to find the relative velocity between the two spaceships as 4x10^8 m/s? From the common inertial frame. It seems like people are simply discounting the valididty of measurements taken from that frame. I thought that one of the tenents of relativity was the idea that no reference frame would be preferred over another. My point is that if two spaceships each travel in opposite directions from a given origin at .999 c, regardless of what they see on their individual ships, there must be some frame that will describe their relative speed as being greater than c. Otherwise, we cannot say that each is traveling from the origin at .99c. It's nonsensical.