Equivalence Principle

I've read about this SR paradox in several threads on sci.physics. The people that are generally recognized as knowledgeable about SR seem to agree that it is a "real" (ie predicted by SR) effect. Time over there is different from time right here. The difference (in SR) is a function of relative position as well as relative velocity. That difference in time leads to all sorts of problems.

This is what I meant when I said - "In SR, maybe. But we already know SR is broken. So just add it to the list of dumb stuff that SR is famous for, and move on to something useful. (Oh, that's right. It's already on the list.)"

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The effect you are referring to is not relativistic. It is Special Relativistic. Analyze it with a reasonable theory of relative motion, such as LR, and the dumb stuff goes away.

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But your point about there being a difference between a stationary g field and an accelerated simulation of a g field is valid - in SR, not in reality. If the SR gurus are right and SR really does predict this, it ought to be a coffin nail.

Unless we go out into space and start breaking threads ...

LB

I don't think that any thread would actually break. The effect should correct itself by radiating energy in some fashion during acceleration similar to a bare electron radiating photons during acceleration.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by EBTX</i>
<br />The effect I am referring to is entirely relativistic. ... During "t", the butt end of the craft is logically constrained to move at a greater velocity than the weight (and must always do so) ... but this is in contradiction to the afforementioned equilibrium. The increased tension in the string cannot cause a signal through it to be transmitted at greater than c.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">If you are talking special relativity (a now-falsified theory), this misapplies SR. In SR, the butt end of the craft, the weight, and the nose all exist at different instants of time because of their speed (not their acceleration, which has no role in SR and must be treated classically, as in my previous messages).

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Hence, there is a genuine logical problem here with SR, GR and acceleration in general.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">I don't agree. Neither do the millions who have studied SR in depth over the past century, and understand at least the mathematical meaning of the Lorentz transformations. There can be no logical problem once you truly assimilate the concept of non-synchroneity of time from place to place. -|Tom|-

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by tvanflandern</i>
<br /><blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Larry Burford</i>
<br />Is there an effect of acceleration that would cause a potential meter to believe that there was a large mass nearby, when there is none? Or, might this be a way to falsify EP?

<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">It has always been true that a clock inside an elevator at rest and one in freefall will instantaneously tick at the same rate. The same is true for a rocket in space, whether accelerating or non-accelerating. Only speed and potential affect clock rates, but not force or acceleration.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Let me rephrase my question. Suppose there is a device that can "accurately" measure the strength of the gravitational potential field at a point, analogous to the way a thermometer can measure temperature at a point.

This device, sitting still on the surface of Earth, will have a particular reading, and that reading will be constant. Very constant. Out in the depths of space, away from any significant mass, the same device will have a different, lower, reading. And this difference will exist even if the device is accelerating at 1 g.

Another difference: Increasing velocity in a given potential field causes the potential field to seem stronger (more dense). So the device, if accelerating while away from large masses, should show a continuously changing value for potential. The reading should start much lower than the surface reading (assuming that initial delta v with the surface lab is zero), and increase in step with the increase of delta v.

Or am I still missing something?



<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"> But an observer inside an elevator could not tell whether clocks in the elevator ticked at one rate or another, and is not allowed to look outside (where he could easily see if the elevator was accelerating or not). -|Tom|-
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<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">I don't agree. Neither do the millions who have studied SR in depth over the past century, <hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
"A" and "B" are two rocket ships at rest relative to one another. "C" is an observer in the middle.

C observes A and B to accelerate in the same direction (A away from C and B toward C) at exactly the same rate.

However, B starts accelerating prior to A (as seen by C) by some small increment of time.

Then ...
B is always travelling at a higher velocity than A and will in time catch up to A, regardless of their accelerations being identical. We're here assuming that they always accelerate until B catches A.

A and B are analogous to points at different distances from the point of acceleration in the "broken string" example given previously. Of course, two different rockets are not electromagnetically connected as in the first example, so there are other factors to be considered ... such as the mass of the ship which affects the acceleration over time (the time it tskes to cover the distance A- and the elasticity of the ship.

If the ship is perfectly elastic from atom to atom, there is a huge logical problem involved in the fact that one point is accelerated first and then the next and the next and so on all the way through the ship over a finite time "t".

To prevent the ship from being crushed or the string breaking, the point furthest away from the acceleration must at some time accelerate at a faster rate than the near point ... or ... the near point must slow down thereby allowing the far point to "catch up". But if the system is perfectly elastic, it can't get out of the "anterior-posterior logical loop".

The solution is the expulsion of energy which serves to break the loop and allow all points to come to equilibrium ... which then appears to be the same state you have in a rocket at rest on the launch pad. The symmetry between gravity and linear acceleration is broken because energy is not emitted by a body at rest in a gravitational field.
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PS. There are not "millions" who have studied SR or GR in depth. There may be perhaps a couple thousand depending on one's definition of "depth of study" ;o)

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by EBTX</i>
<br />"A" and "B" are two rocket ships at rest relative to one another. "C" is an observer in the middle. C observes A and B to accelerate in the same direction (A away from C and B toward C) at exactly the same rate. However, B starts accelerating prior to A (as seen by C) by some small increment of time. Then ... B is always travelling at a higher velocity than A and will in time catch up to A, regardless of their accelerations being identical.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">That may be true in your common sense or even in mine. But it is definitely false in SR. Your conditions are contradictory in SR.

Start with a simple symmetric situation -- A, C, B all at relative rest and equally spaced along a line. Time is common to all three.

Now let A and B change to another inertial frame while remaining at rest with respect to one another. The symmetry is instantly broken because, if the AB frame moves so that A approaches and B recedes from C, then A is in C's future and B is in C's past. (This has nothing to do with light propagation speed, but real, physical time -- according to SR.)

The faster the AB frame moves relative to C, the greater is the time discrepancy. So judgments about who changes speed first are impossible in SR because they refer to remote events, which cannot possibly be synchronous in more than one frame.

If you don't get that part about SR, you will never grasp the theory. Of course, you don't need to because it is now falsified in favor of LR. But if you wish to be a good historian, you need to understand what SR really said about reality.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">There are not "millions" who have studied SR or GR in depth. There may be perhaps a couple thousand depending on one's definition of "depth of study"<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">There are sometimes over 1000 showing up at the annual conferences these days. But I was referring to all the physics students who have ever been taught relativity and had to understand it well enough to pass exams during the past century. -|Tom|-