Does light have a mass?

[Prosoothus]

137,

Did you calculate the number of times [just curious] or did you guestimate. I hope to see the actual calculation, with an assumption of a perfect setup. Given modern technology and computational power, my assumption is that a device could be built. If there is a standard and repeated error, it would be possible to calculate for this to see if statistically there is still a non-calibration error tendency for the light to descend due to gravity.

It was a guestimate.

Now when I think about it, there would be a way to calibrate the device:

1. First you would bounce the light off the mirrors a few million times.

2. You would then mark the location of the light on the mirror.

3. You would turn the device upside down.

4. You would bounce the light off the mirrors a few million times, again.

5. You would mark the location of the light on the mirror again.

6. You compare the mark from step 2 with the mark from step 5. If both marks are in the same location, then gravity has no effect on the light. If they are not in the same location, then the distance between the marks is directly proportional to the strength of the gravitational field.

Tom

 

[(Q)]

The question is how can relativists say that something speeds up or slows down, when they claim that there is no absolute frame of reference?

Exactly. There is no absolute frame of reference, that's why we have relativity. We know the Earth and the universe are in constant motion. We know a rocket can accelerate away from the Earth. But while riding in that rocket looking back at the Earth, I can't tell you for sure if it is me that is accelerating away from the earth or vise-versa. Therefore my motion is 'relative' to the motion of the Earth.

If there was an absolute frame of reference, we wouldn't need relativity. We could make all of our calculations based on that one reference point. What could be that absolute frame of reference; the Earth, the Solar System, the Galaxy, another Galaxy, What ?? What is that one coordinate we could base all other coordinates ??

Answer: there isn't one.

If the observer speeds up while the universe is at rest the time will slow down for the observer compared to the universe.

Where in the universe ?? What reference point ?? What coordinate ?? The rest of the universe is all around us and not one particular point of reference. Plus, all other objects in the universe are in motion, ALL of them.

However, if the universe is travelling close to c with the observer, and the observer speeds up relative to the universe(in reality he slows down), won't the observer's clock run faster than the clock moving with the universe???

How does an observer speed up relative to the universe and in reality is slowing down ?? I don't get this.

 

[137]

Who is who

Q,

No problem. But I think you're misunderstanding. The 'stationary' twin can be on Earth or floating in space, it doesn't really matter. It is the twin that is accelerating away in his ship who is at rest in a gravity well.

SR and the whole thrust of the theory is that either framework can be equally considered at rest[edited this in later>>Or either can be considered the accelerated framework. If there is no absolute, then why should one be given preferential treatment by the pseudo-gravity? Most of the posts of relativity proponents seem to illustrate RTs in this light.] Unless you are claiming that this is not true. Are you saying that SR states that one can definitively state that one is an accelerating twin? Your definition or parameters of what is accelerating and what is at rest seems to fly in the face of what many folks claiming to be knowledgeable of relativity say...this includes physicists within the hallowed halls of acedemia.
The paradox was not contrived by 'those who did not understand SR. ' it flows directly from Einstein's elucidation of SR. I think you might want to rephrase your statement. There are a good plenty of Relativists who relish 'proving' the twin paradox and using it to prove SR.
What I read is that it DOES matter who is at rest when the twin paradox is explained as solved, but then you state, 'There is no absolute frame of reference, that's why we have relativity.' If there is no absolute frame of reference, then either twin can be considered moving at near the speed of light and coming back less aged than the other. Self-contradictory, unless one sticks to the formula and the fact that it is illuminating the information transfer and not a physical reality.

Prosoothus, On first glance this sounds like a simple way to do the test, even with calibration error [though precise mirror rotation may be a logistical nightmare...but possible].

Good evening to all,

137

 

[137]

Another Nasa site

Goddard Space Flight Center

Still within the Virgo cluster of galaxies, Mushotzky will create precision maps of the temperature and chemical abundance of the gas. For this, he relies on Chandra's superior spectral resolution. He said a bonus of the Virgo observations will be studying quasars far behind the cluster. He is interested in the way gas from the cluster affects quasar observations. Perhaps the gas bends or magnifies the quasar light, creating a space mirage.

Dr. Gerard Williger is studying the region of the sky toward a distant quasar, called Q 1429-007, which is billions of light-years away. The quasar appears to have two identical images, which implies that there is a large mass in front of it whose gravity bends the quasar light to form two images in our direction. This is called a gravitational lens, and the culprit might be a galaxy cluster in between the quasar and us. Massive clusters can contain around 1,000 galaxies. More importantly, they also have a lot of hot gas between the galaxies, making a type of cosmic "soup". The multi-million-degree gas gives off X-rays.

Note how one scientist focusses on gas bending light and referring to it as a space mirage while the other focusses on two 'identical' images to prove gravity lensing, yet they may 'also have a lot of hot gas between the galaxies, making a type of cosmic "soup". '

So gasses cause a mirage, but gravity lensing causes multiple images.
Two separate forces can ply their respective wares and cause observable phenomenon. But these phenomenon should be catalogable by their data, so that the proper variables and corresponding formulas of affect can be established. Then the formulas can be tested for predictive usability. More to the point, all variables should be accounted for to pinpoint the cause, rather than to ascribe to gravitational lensing all proported cosmic light bending.
***Source books and physics sites online still all point to Eddington's proof of sun's gravity bending light as the fait accompli regarding Relativity...I guess as an equivalence to Eureka. I would assume all scientists would say that the repeatability is needed. I read at one site that Eddington's original photo plates are no where to be found [I do not know how true this is..if so there should be a way overdue search.] Vague hints at X-ray bending as proof, but no data or sources yet.
More and more solar scientist data points at the importance of the sun's emissions and coronal 'soup' which has tremendous affect on EM and light. Hmmm, can this be easily discounted? I hope to amass the data for sun's bending and coronal/solar affects.

****This is tossed off**** On the twins, again. If Earth's gravity slows clocks, there should be a gravitational formula that synchronizes this claim. If the near speed of light 'travelling twin 'goer' is bathed in psuedo-gravity then his clock should be slowed down, too, and the formulas should predict this. The closer the speed of light the greater the pseudo gravity, the slower the clock. So why is the travelling twin younger?

137

 

[(Q)]

If the near speed of light 'travelling twin 'goer' is bathed in psuedo-gravity then his clock should be slowed down, too, and the formulas should predict this.

His clock does run slow according to GR.

The closer the speed of light the greater the psuedo gravity, the slower the clock.

No. Only while accelerating, decelerating and turnaround.

So why is the travelling twin younger?

Again, while he is accelerating, decelerating and turning around to go back to Earth, he is bathed in a pseudo-gravitational field and thus is sitting at rest in a gravity well. Clocks tick slower in gravity wells.

 

[137]

Contrary to Einstein?

But Q you are using GR to explain SR, are you not? Einstein may not have explicitly created the Twin Paradox, but he commented on it as an elaboration upon his clocks/platform discussion. He stated [and I will have to find his quotes if you question them] that acceleration does not need to be taken into account to 'solve' for these equations[as most contemporaries say, 'the effects are negligible.'] We can remove the stop and return acceleration by creating a looping path, if you want to try it this way.
Your explanation uses SR to slow time, then GR to slow it down then it's SR to slow time again until the twins are reunited.
Gravity well is not a term I am going to entertain, yet, AND it is not necessary according to Einstein's description of SR. I thought gravity or its equivalent acceleration formulas showed a speeding up of clocks?***I mis-spoke last time---I meant to ask why pseudo gravity slows clocks as opposed to speeding it up.***

SR should be able to stand on its own regarding the two clocks/twins moving at different rates.

Can you answer the proposition that according to SR there is no preferred FOR and that either one can be considered moving away? Am I wrong that in some posts you have stated that, according to Relativity, no one can say whether an object is thrown away from the earth or the earth is thrown away from an object. If I follow your current line of reasoning, there is one twin who is pinned as an absolute: The stationary twin. If this is so, then there is a definable relationship that is asynchronous. Stationary must mean stationary relative to something? What is it stationary in relation to? How can relativity be relativity as taught and understood [by most] if there can be a defined, one-sided FOR which is the measure of the relationship or comparison betwixt FORs?

I still hold that SR is referring to is the transfer of data via light. Einstein points to this, Born says we are talking of appearances, Eddington mentions appearances [at least in some instances], science popularizer Isaac Asimov speaks of measurement as being the key issue of SRs focus. The list goes on..much of it from esteemed scientists over the last 100 years with much contradiction.
Lorentzian formulas use light speed as a limit of data communication, why else would this speed limit be used. The speed of light is not part of a formula for looks. The speed of light is part of the equation as it relates to data transfer NOT existence. I am reading some sites that try to de facto state that clock rate slowing is the SAME AS a human's biological clock. This is the sort of untested extension of the misguided application of relativity that is running rampant.

Take my flippant example of pre-scientific humanity thinking that a wave of water in a river is the fastest speed. You use the speed of this wave in the Lorentz formulas and if you came to the conclusion that time dilates or boats are shortened the nearer to the speed of the wave form on the river, you would not be taken seriously. [I can see a response from the unquestioning Relatavist, 'Ah, but because we know that time dilates and rods are shortened, we know that this flippant example is correct, but disordered in its characters not knowing the true speed limit of the universe]

regards,
137

 

[(Q)]

But Q you are using GR to explain SR, are you not?

No. I'm simply explaining the Twin Paradox with GR. There are several ways to explain the so-called paradox with SR.

Your explanation uses SR to slow time, then GR to slow it down then it's SR to slow time again until the twins are reunited.

Nope. I only use GR. Clocks tick slower in a gravity well in any reference frame.

Gravity well is not a term I am going to entertain, yet, AND it is not necessary according to Einstein's description of SR. I thought gravity or its equivalent acceleration formulas showed a speeding up of clocks?

Not if you are the one sitting in the bottom of the gravity well. Your clock is ticking slower then if you were at the top of the gravity well.

SR should be able to stand on its own regarding the two clocks/twins moving at different rates.

It does. The reason why is because there is NO paradox.

Can you answer the proposition that according to SR there is no preferred FOR and that either one can be considered moving away?

Yes, and each will view the others clock as ticking slower relative to their own.

Am I wrong that in some posts you have stated that, according to Relativity, no one can say whether an object is thrown away from the earth or the earth is thrown away from an object.

Yes, from the FOR of the object being thrown away and the object doing the throwing.

If I follow your current line of reasoning, there is one twin who is pinned as an absolute: The stationary twin. If this is so, then there is a definable relationship that is asynchronous. Stationary must mean stationary relative to something? What is it stationary in relation to?

Remember, there is NO absolute frame of reference. The Earth bound twin views himself as stationary relative to his surroundings, the ground he is standing upon. the accelerating twin views himself as stationary relative to his surroundings, the inside of his ship. Both can view themselves as stationary relative to their surroundings and relative to each other. Both can view the other as moving away relative to their surroundings. Both will view the others clock as ticking slower relative to their own clock.

 

[137]

And this is at issue

Remember, there is NO absolute frame of reference. The Earth bound twin views himself as stationary relative to his surroundings, the ground he is standing upon. the accelerating twin views himself as stationary relative to his surroundings, the inside of his ship. Both can view themselves as stationary relative to their surroundings and relative to each other. Both can view the other as moving away relative to their surroundings. Both will view the others clock as ticking slower relative to their own clock.

Then you ARE stating that we are talking about the signals of each clock being the 'victims' of relativity? If you are stating this, then this is the point I have been trying to illustrate. If you are equating this signal delay with variations in the duration of existence, then I contend that this is the erroneous path that many people infer from SR.

Not if you are the one sitting in the bottom of the gravity well. Your clock is ticking slower then if you were at the top of the gravity well.

I will leave gravity wells to GR and beyond. Until I read up on GR, the formulas, implications and proofs.

It does. The reason why is because there is NO paradox.

&

There are several ways to explain the so-called paradox with SR.

I would like to see your version of the SR solution to the paradox. If the paradox is resolved by the correct usage of SR in calculating the delayed information transfer, then I agree that there is no paradox. If you, rather, still hold that one twin actually ages less due to formulaic conclusions, then the paradox remains.

137

 

[137]

Taylor & Wheeler [1992, 76]:

Taylor & Wheeler [1992, 76]:

Does something about a clock really change when it moves, resulting in the observed change in the tick rate? Absolutely not! Here is why: Whether a clock is at rest or in motion ... is controlled by the observer. You want the clock to be at rest? Move along with it. ... How can your change of motion affect the inner mechanism of a distant clock? It cannot and it does not.

does anyone know what book or publication this came from. I would like to verify the quoted writing. I have read some folks citing T & W as defenders of the orthodoxy of relativity.

cheers,
137

 

[(Q)]

Then you ARE stating that we are talking about the signals of each clock being the 'victims' of relativity?

Where did I state that ?

If you are equating this signal delay with variations in the duration of existence, then I contend that this is the erroneous path that many people infer from SR

Nope. I don't remember saying that. You're either twisting my words to conform to your ideals or you just don't understand it.

I would like to see your version of the SR solution to the paradox. If the paradox is resolved by the correct usage of SR in calculating the delayed information transfer, then I agree that there is no paradox. If you, rather, still hold that one twin actually ages less due to formulaic conclusions, then the paradox remains.

OK, here's one. One twin takes off at a high fraction of c and travels for a number of light years and then returns to his Earthbound twin to compare their elapsed times. But a number of light years measured by who ? (X) amount of light years measured by the Earth bound twin is not measured the same by the moving twin. Due to length contraction, the distances are measured differently by both twins. The Earth bound twin will measure (X) amount of light years distance more than the moving twin will measure the same distance. The turnaround point and the Earth belong to the same inertial reference frame.

Therefore the moving twin travels less measured distance compared to the Earth bound twin's measured distance. It works out the same regardless of whose frame of reference you use as a rest frame.

So you see, there is no paradox.

 

[137]

This

Both will view the others clock as ticking slower relative to their own clock.

To view each other's clock is to view the signal reception. The signal is separate from the event- separated upon transmission. This is what I read in your statement.

137:If you are equating this signal delay with variations in the duration of existence, then I contend that this is the erroneous path that many people infer from SR. Q:Nope. I don't remember saying that. You're either twisting my words to conform to your ideals or you just don't understand it.

I am trying to understand if your claim is that the each twin's viewing of the reciprocal clock as being slower is due to a]delay due to the speed limit of light transmission or b]due to a slowing of existence by one or the other twin.

But a number of light years measured by who ? (X) amount of light years measured by the Earth bound twin is not measured the same by the moving twin. Due to length contraction, the distances are measured differently by both twins. The Earth bound twin will measure (X) amount of light years distance more than the moving twin will measure the same distance. The turnaround point and the Earth belong to the same inertial reference frame.

1.Either twin can be considered moving away at near light speed, so whichever one is considered the measurer will measure the same. Paradox still intact
2. The speed of light is invariant in any frame, lightyears do not contract or dilate. A lightyear is a lightyear, unless you want to say that light speeds up or slows down depending upon the speed of a traveller. One cannot arbitrarily start to adjust the invariance of light in order to solve an equation.
3. I asked for formulas regarding SR's ability to remove the paradox. If you have a site to cite, a book that addresses this mathematical issue, or a journal of physics that can SR the twin paradox, then please post it. If you can do the calculations and post them yourself, that would be just as valid.

To state that one doesn't understand relativity because of dialogue on the claims being hammered out is not a sign of a strength of subject.
Dunno if I can post anymore to day...we'll see. Enjoyed it immensely,
137

 

[(Q)]

1.Either twin can be considered moving away at near light speed, so whichever one is considered the measurer will measure the same. Paradox still intact

Wrong. They will measure the distance differently due to length contraction. The Earth bound twin is considered the rest frame in this example but you can use the other twin as the rest frame. No paradox.

2. The speed of light is invariant in any frame, lightyears do not contract or dilate. A lightyear is a lightyear, unless you want to say that light speeds up or slows down depending upon the speed of a traveller. One cannot arbitrarily start to adjust the invariance of light in order to solve an equation.

We are talking about the distance traveled at the speed of light in one year. Are you not aware of that concept ?

3. I asked for formulas regarding SR's ability to remove the paradox. If you have a site to cite, a book that addresses this mathematical issue, or a journal of physics that can SR the twin paradox, then please post it. If you can do the calculations and post them yourself, that would be just as valid.

Gamma = 1 / sqr.rt 1-v^2/c^2
v is the velocity of the object

At .9c (600 million mph), (1) meter would have a length of (.44) meters.

Plug in any velocities you wish. No paradox.

 

[James R]

137,

You have given me a lot to respond to.

<i>The sun will be the focus for lensing.</i>

Ok, if you want to pursue that. Let me remind you that most work in gravitational lensing these days involves galaxies, though.

<i>So far in my reading, there is no formula that logically concludes that 'Aha, spacetime curves!!' it is an attempt to illustrate the mysterious gravity. It could have been called uniform suction of consolidated matter, but that doesn't sound as swell.</i>

You're moving out of your self-defined area of interest (special relativity) into the realm of general relativity with this. Special relativity has no curved spacetime.

In fact, when you look at it, practically <b>all</b> the important formulae in general relativity say "aha! spacetime curves!". GR is based on Riemannian geometry, which is the geometry of curved spaces.

<i>No amount of summing a continuous halving of remaining distance will ever total one; without limits, mathematically the number will ALWAY total as less than one.</i>

Luckily, we have techniques for summing infinite series which are well understood and give the right answers.

<i>The paradox illustrates where certain mathematical postulates descend one into nonsense.</i>

That's funny. I thought I'd just demonstrated why is <b>isn't</b> nonsense.

<i>If we remove the signalling of death component, since this concerns ONLY the ability to communicate an event, we are left with the faster twin living in slower time in comparison to the stay at home twin. This comparison presupposes the neutral mind of the physicist theorizer.</i>

No. The comparison relies on the specification of an observer; that is all.

<i>If we remove the clocks from both twins sight, and so remove the physical device that they are trying to read from, what is dialated?</i>

Time. Measure it however you like. Measure it by the rate your heart beats. Measure it by using a ticking pendulum. Or an atomic clock. Or a water clock. Or whatever. It doesn't matter.

<i>Let us also remove any desire for the twins to communicate their positions or their times of death. How is existence slowed down?</i>

If they don't communicate, then presumably they are only interested in their immediate surroundings. In that case, neither twin sees anything unusual in his own frame of reference. It is only when he looks "outside" that he sees effects such as time dilation and length contraction.

<i>If the time dialation component is merely an illustration of the limits of communication of location and time, then you have a believer of sorts, right here and now. My understanding, though, is that time dialation is treading on the grounds of a mathematical paradox.</i>

Time dilation has nothing to do with the limits of communication, as I pointed out previously. It is a separate effect which arises due to relative motion. There is no paradox involved.

<i>When I preset my dying twin paradox with a 'they will die in one minute' and send them on their merry way, the time dialation generality is that the travelling one will die later. What if I said, instead, 'the twins will die at the same time? There is a paradox for you. Then you would have to pick a point in space for both twins and say, 'Here and here are where the twins were when they died.' Now what happens? If you do not know the preset synchronous nature of the twins dying, you do not necessarily end up with an asychronous solution.</i>

When you make a statement like "Twin A dies at time t1", relativity tells us that you <b>must</b> specify a frame of reference, otherwise the statement is meaningless. If you ask "How far is it to the post office?" and I tell you "It is 3 kilometres", my answer is meaningless unless I tell you 3 km from which point. 3 km from my house, or 3 km from the city centre? My measurement of the distance is relative to something. So are any measurements of time.

<i>Please tell me you are not saying, 'Time dialation is real and does not depend on light communication, and here are the results of twin dyings: The relativistic formula shows that the light signal of death proves the twin died later than 60 seconds.' Either the formulas predict actual time dialation or we are being asked to a priori accept that time dialation occurs on faith and the formulas are merely presenting the time delay in communicating this truth.</i>

I've already explained that the time dilation formulae describe real time dilation, separate from any communication issues.

<i>Yep...SR is and has been my focus.</i>

Then leave the curved spacetime alone for now.

<i>I still contend that it is an absolute necessity to test for gravity's affect on light.</i>

Why not sort out your issues with special relativity first? GR is a lot harder.

<i>3. Another version of the twin paradox. Two twins. One goes off at near the speed of light and returns. When he returns who is older? By relativity's own standards it does not matter who is the 'go-er.' Each framework can be equally referred to as the one who is moving off near the speed of light. So the relativity answer should be, either one of them could be the older one.</i>

Yes. 100% correct to this point.

<i>And herein is the contradiction that cannot be glossed over. The only reconciliation is that, as the wisest of relativity proponents state, we are talking ONLY of measurements, nothing more.</i>

No, that is not the "only reconciliation". You have to understand the apparent paradox. There is symmetry between the twins whilst they are travelling at constant speed relative to each other. As soon as one of them accelerates that symmetry is broken and their observations are no longer the same.

<i>b]Einstein did not consider the acceleration/deceleration to matter in his writings on SR.</i>

Are you sure about that? Have you found where he discusses the twin paradox?

<i>c] SR is the home of the Twin paradox. Are you saying the SR is incorrect for the Twin Paradox[and by extension the clock slowing and rod shortening] and can only be corrected by the GR?</i>

SR can handle the twin paradox. BTW, it's not a real paradox. Relativity resolves the apparent paradox.

<i>Only by nature of the formulas, that set up a proportion with light speed as its top limit do we end up with calculations of time slowing and rods shortening.</i>

More accurately, the assumption that the speed of light is the same in all inertial reference frames leads to the length contraction and time dilation results.

<i>The atomic clocks on planes and GPS show a slowing of decay rates, but I am still not seeing conclusive proof that this is due to either of the relativity's calculations.</i>

You mean, despite the fact that the predicted amount by which the times differ matches the predictions of relativity very accurately? Seems like good evidence to me. Of course, conclusive proof is impossible in science (except mathematics).

<i>This is a legitimate question: Do the computers on board planes, supersonic or otherwise, or satellites, or computers also slow down?</i>

Yes. Everything slows down. Time slows down <b>relative to an Earth observer</b>.

<i>The root cause should be investigated, as opposed to just saying SR & GR did it.</i>

If SR & GR <b>didn't</b> do it, the amount of time difference should be different from what is predicted by SR and GR, wouldn't you say? What are the chances that SR and GR just <b>happen</b> by chance to give the correct predictions?

<i>As stated in a previous post, a NASA site that discusses GPS states that 'the affects of relativity are negligible.'</i>

Didn't we cover that before? GPS would not work correctly if corrections were not made for relativistic effects.

<i>I am curious if batteries, electricity, CMOS gates, etc., all slow down? If so, is the slowing rate consistent?</i>

Yes.

<i>On yet another thought toss out; lets say that Einstein was born in the time of the Neaderthal. He was the younger brother of Lorentz. As a Child Einstein imagined running as fast as a wave along the river he lived by. Aha, for the wave to continue being a wave, it must not be affected by my speed. A wave will always measure the same speed no matter what speed I go.</i>

That is not what is observed with water waves. The apparent wave speed clear varies depending on how fast you run. Run fast enough and you can be stationary with respect to a wave crest. But you can't do that with light.

The rest of your thought experiment is therefore based on an incorrect premise - that the wave speed is constant for all inertial observers. Not true for water waves, but true for light.

<i>SR and the whole thrust of the theory is that either framework can be equally considered at rest</i>

Yes.

<i>Or either can be considered the accelerated framework.</i>

That's harder. An accelerated reference frame is non-inertial. You need to be very careful when you work in accelerated frames, but it is possible.

<i>If there is no absolute, then why should one be given preferential treatment by the pseudo-gravity?</i>

The answer to that is somewhat complicated. We'd really need to diverge into a discussion of Mach's principle and other things, which I won't do for now.

<i>...So gasses cause a mirage, but gravity lensing causes multiple images.</i>

That's loose "journalist-speak" to try to get an idea across. In any case, perhaps you could explain how a mirage might produce multiple images?

<i>SR should be able to stand on its own regarding the two clocks/twins moving at different rates.</i>

It can and it does.

 

[137]

more

Q,

Wrong. They will measure the distance differently due to length contraction. The Earth bound twin is considered the rest frame in this example but you can use the other twin as the rest frame. No paradox.

How can only one twin measure differently. If each twin views the other clock as moving more slowly, won't each twin view the other's rods as shorter? Does SR theory say both FORs are equivalent, yet one FOR has the 'real' affects and the other is an illusion?

We are talking about the distance traveled at the speed of light in one year. Are you not aware of that concept ?

Invariance speed of light in every frame = invariance of light year in any frame of reference? Are you saying a lightyear can be measured differently than the distance traveled at the speed of light in one year? Is this the concept you are wondering whether I get?

Gamma = 1 / sqr.rt 1-v^2/c^2
v is the velocity of the object At .9c (600 million mph), (1) meter would have a length of (.44) meters.

You have merely used the formula to 'explain' the shortening of rods. This answer does not de-paradox the twin scenario.

James R,

Let me remind you that most work in gravitational lensing these days involves galaxies, though.

Most work may be done on galaxies, but this focus evades the issue. If the sun can lense light, as the closest most massive body, it is emminently more accessible to verify claims to gravitational lensing. To claim lensing for further and further objects is to assume lensing works and is the overriding light focussing phenomenon. I contend that if gravitational lensing by the sun is possible, then it should have a body of data compiled for all physicists to peruse. Any comments on bouncing light on earth and testing for the affect of gravity on the beam?

That's funny. I thought I'd just demonstrated why is isn't nonsense.

There is nothing invalid in my assertion that the halving goes on indefinitely, never achieving completing the mathematical journey, UNLESS there is mathematical intervention or limits. One has to define the acceptable order of magnitude one is willing to allow in a formula.

Measure it however you like. Measure it by the rate your heart beats. Measure it by using a ticking pendulum. Or an atomic clock. Or a water clock. Or whatever. It doesn't matter.

Ahh, but it does matter. When SR was first put forth, there could not have been a mentality of 'if clocks tick slowly when they fly faster, all physical processes do the same, including existence itself!'and then everyone just accepts that this is a fact for all physical processes. This in itself would be one of the most far reaching conclusions ever accepted. Testing the validity of all manner of processes is what is needed [there should be plenty of data out there.] As far as my research has shown to date, there have been no experiments on the human heart going slower. If there are experiments, then they would have to be thick with analysis of all physiological processes and how their interations are affected. The all-=encompassing cannot be assumed. Time dilation is about reading clock signals not about existence. It is about the limits of measurement, and as such it is valid.

Time dilation has nothing to do with the limits of communication, as I pointed out previously. It is a separate effect which arises due to relative motion. There is no paradox involved.

Then why is the speed of light an integral component of the formula? The formula deals with the transmission of information, it does not explain physical effects. The formula has no inherent structure which proves that time itself is dilated of rods shortened. It is about the limits of measurement. I will soon add a list of quotes from Relativists which state that it is about measurement.

When you make a statement like "Twin A dies at time t1", relativity tells us that you must specify a frame of reference, otherwise the statement is meaningless.

Meaningless, no...a myriad of possible calculations, yes. There should be no problem using SR in reverse, a calculus formula to find the possible structure and map out possibilities. Frame of Reference was given, the challenge is that the calculations must be done in reverse to find possible solutions.

I've already explained that the time dilation formulae describe real time dilation, separate from any communication issues.

What do you make of the quote:
Taylor & Wheeler [1992, 76]:

Does something about a clock really change when it moves, resulting in the observed change in the tick rate? Absolutely not! Here is why: Whether a clock is at rest or in motion ... is controlled by the observer. You want the clock to be at rest? Move along with it. ... How can your change of motion affect the inner mechanism of a distant clock? It cannot and it does not.

As previously stated, I am looking to see if the proponents of RT actually said this.

Why not sort out your issues with special relativity first?

On understanding the GR and attendant tensor calculus as fully as possible, you are correct, BUT experimental evidence of sunny lensing should exist whether I am chin deep in Einstein and Minkowsy or not.

Are you sure about that? Have you found where he discusses the twin paradox?

You are correct to hold me to my own standards. I will research and find documentation. If there is none to be found, I will state this as well and chalk it up as incorrect citation. Fair enough?

Relativity resolves the apparent paradox.

For some, relativity causes the paradox. Depends on the FOR regarding the theory.

You mean, despite the fact that the predicted amount by which the times differ matches the predictions of relativity very accurately? Seems like good evidence to me. Of course,conclusive proof is impossible in science

The predicted amount versus actual measurement is what I would like to have access to. To make a point using the Eddington photo plates, the claim is the same as your statement 'prediction matches measurements very accurately,' yet the reality of the data is quite a bit more sloppy from the scientific standpoint. It is cleaned and polished for common consumption.

Everything slows down. Time slows down relative to an Earth observer

Physical processes may slow down in varying manners...light does not. Time measuring devices slowing down do not by necessity mean that existence slows down.

What are the chances that SR and GR just happen by chance to give the correct predictions?

Depends upon the parameters of correct. Since RTs are dealing with physical events, such as accelerations, gravity, then any experiment looking into RTs validity are going to have changes in the objects of observation. RTs are mathematical tools used to manage diverse phenomenon and are rooted in historical inquiry that were dealing with the same issues. I do not take RTs to be in the realm of fantasy, but I also think that there is confusion as to what they are actually 'explaining' and not enough honest evaluation of the data which 'proves' the tools to be 'very accurate.'

Didn't we cover that before? GPS would not work correctly if corrections were not made for relativistic effects.

Basically, the dialogue went ' GPS works due to relativity,' and I mentioned that the nasa GPS site said relativistic effects can be ignored AND that the myriad of satellites going in every which direction would all be in different states of clock slowing, etc. yet there is a prelauch retardation of clocks and then all is fine and then I said there should be hard data that would put the whole debate to rest, but none is forthcoming, blah blah blah.

That is not what is observed with water waves. The apparent wave speed clear varies depending on how fast you run. Run fast enough and you can be stationary with respect to a wave crest. But you can't do that with light.

But isn't this the childhood thought of Einstein that was the seed of SR? That if you ran as fast as light, what would you see. How could light still be light. If one ran as fast as the water wave, the wave is still a wave. I will ponder this more, because I think that contrasting the two very different phenomenon may be illuminating or drenching.

In any case, perhaps you could explain how a mirage might produce multiple images?

Long desert highway drives give evidence of the multiple mirage. If there are multiple refracting areas that are visible to the observer a single approaching vehicle can be seen in multiple road reflections. If anyone has not seen this...take a road trip and see for yourself.

Sound good to leave Non-inertial/inertial and Mach
on the shelf for now.

I am gonna have to keep a task list for myself to honor my calims at data...

Great responses. G'night.
137

 

[Crisp]

Reference for the quote

Hi 137,

The quote from Taylor and Wheeler you refer to is from their book "Spacetime Physics", 1992 edition, page 76 (in the middle of the page). I happened to have that book on my bookshelf . Complete reference:

Edwin F. Taylor, John A. Wheeler
"Spacetime physics: introduction to special relativity, second edition"
W.H. Freeman and Company, New York (1992) - page 76.
ISBN 0-7167-2327-1

I wouldn't recommend the book as an introduction to SR though, it is far too intuitive and tries to avoid math as much as possible.

Bye!

Crisp

 

[James R]

137,

<i>If the sun can lense light, as the closest most massive body, it is emminently more accessible to verify claims to gravitational lensing.</i>

No. Closeness is not the only relevant criterion for accessibility in this case. Another one is mass. Galaxies are <b>much</b> more massive than the sun, which means they can bend light more.

<i>I contend that if gravitational lensing by the sun is possible, then it should have a body of data compiled for all physicists to peruse.</i>

Yes. I'm sure the data is there, but I'm not going to look for it. For a myriad of other reasons I am convinced that relativity is correct (to a certain level of accuracy). If you're worried about it, you can look into it. I'll be interested to hear your findings.

<i>Any comments on bouncing light on earth and testing for the affect of gravity on the beam?</i>

It's a GR experiment, and in the form presented previously it would not work, for various reasons which I do not really want to get into at this stage. That's why I didn't mention it before.

<i>There is nothing invalid in my assertion that the halving goes on indefinitely, never achieving completing the mathematical journey, UNLESS there is mathematical intervention or limits. One has to define the acceptable order of magnitude one is willing to allow in a formula.</i>

No. We can calculate this <b>exactly</b>, using standard mathematical techniques. No approximation is required.

<i>When SR was first put forth, there could not have been a mentality of 'if clocks tick slowly when they fly faster, all physical processes do the same, including existence itself!'and then everyone just accepts that this is a fact for all physical processes. This in itself would be one of the most far reaching conclusions ever accepted.</i>

True. It <b>is</b> one of the most far-reaching conclusions ever accepted. Relativity is an amazing, counter-intuitive theory. Which happens to be right (for all tests so far).

<i>Testing the validity of all manner of processes is what is needed [there should be plenty of data out there.]</i>

Such testing is not necessary, because the conclusion that time dilation happens is not derived with reference to any particular physical process. The argument is a general one to do with space, time and relative motion. Therefore it is generally applicable to any device or system moving in space and time.

<i>As far as my research has shown to date, there have been no experiments on the human heart going slower. If there are experiments, then they would have to be thick with analysis of all physiological processes and how their interations are affected.</i>

You've explained why there have been no such experiments in your second sentence. The effect would be too difficult to separate from all the other factors involved. That would make for an exceedingly poor test of relativity. When you do a fundamental test of an effect, you look for simple examples with few variables, not an incredibly complicated system where the effect you're looking for is swamped by many other effects.

<i>Time dilation is about reading clock signals not about existence. It is about the limits of measurement, and as such it is valid.</i>

That is incorrect. You're downplaying the insights relativity gives us into the nature of space and time.

<i>Why is the speed of light an integral component of the formula?</i>

That's just the way it turns out. Remember, relativity is based on just two postulates, which are justified retrospectively by the predictions matching the experiments and observations. An entire theory of spacetime based on <b>only two</b> postulates! There are few more elegant and powerful theories in physics, or any other field for that matter.

<i>The formula deals with the transmission of information, it does not explain physical effects. The formula has no inherent structure which proves that time itself is dilated of rods shortened.</i>

That's what the formula tells us straight out! You only need to read it correctly. It is not about transmission of information. I've already explained why (twice).

<i>What do you make of the quote:</i>

Does something about a clock really change when it moves, resulting in the observed change in the tick rate? Absolutely not! Here is why: Whether a clock is at rest or in motion ... is controlled by the observer. You want the clock to be at rest? Move along with it. ... How can your change of motion affect the inner mechanism of a distant clock? It cannot and it does not.

I agree with it.

<i>Physical processes may slow down in varying manners...light does not. Time measuring devices slowing down do not by necessity mean that existence slows down.</i>

I have an important question for you. Think carefully, and please answer me:

<b>If we do not judge the rate of "existence" by using time-measuring devices, how do we judge it?</b>

In other words, how would you tell if a clock slowed down but "existence" did not? Please give me an example, if you can come up with one. If you can't, I'm afraid you'll have to accept that the rate of "existence" is measured with clocks.

<i>... isn't this the childhood thought of Einstein that was the seed of SR? That if you ran as fast as light, what would you see.</i>

Yes. Einstein realised that you could never see the crests and troughs of the light wave as "stationary" relative to you - unlike water waves. <b>That</b> led him to relativity.

 

[(Q)]

How can only one twin measure differently. If each twin views the other clock as moving more slowly, won't each twin view the other's rods as shorter?

Yes. Each twin will view their own clock as ticking normal and will view the other twins clock as ticking slower. Each twin will measure their own rods at one meter and the other twin's rod at (.44) meters. Therefore one twin measures differently than the other relative to their own measurements.

Does SR theory say both FORs are equivalent, yet one FOR has the 'real' affects and the other is an illusion?

The FOR in which you choose to be the rest frame, the frame you ar viewing from, the frame in which everything appears normal to you within your surroundings, regardless of whether you are in the ship moving at .9c or whether you're standing on the Earth, is the FOR you would measure one second to be one second and one meter to be one meter. This is this frame in which you measure the OTHER frames effects. The OTHER frames, relative to your FOR, will be measured to experience the effects of SR, time dilation and length contraction.

Invariance speed of light in every frame = invariance of light year in any frame of reference? Are you saying a lightyear can be measured differently than the distance traveled at the speed of light in one year? Is this the concept you are wondering whether I get?

No. For example, the distance to the nearest star is approx. (4) lightyears. In other words, light propagating from that star takes about (4) years to reach us. The distance can be calculated to about 37.6 trillion kilometers.

You have merely used the formula to 'explain' the shortening of rods. This answer does not de-paradox the twin scenario.

I'm trying not to hold your hand through the entire explanation but am allowing you to put some of the pieces together yourself. Think it through. I calculate one meter to be one meter from my FOR. For the twin moving at .9c, his meter will measure (.44) of a meter. If the twin travels to the nearest star and back, a distance of about 8 lightyears (75.2 trillion miles), he will have traveled about 3.5 lightyears (33 trillion kilometers).

When he returns to Earth and the twins compare clocks, the Earth bound twin will have aged more than the moving twin. No paradox.

 

[137]

Experimental validity is relative

James R,

Closeness is not the only relevant criterion for accessibility ...Galaxies are much more massive than the sun, which means they can bend light more

Of course it is not the only criterion that can be taken into consideration. But if it is measurable in our vicinity, then bent light data from within our solar system is a much better realm for study. If we can study all of the phenomenon in our local frame and understand all the variables which affect measurements we can more honestly evaluate distant phenomenon. This can be looked at as an opinion, but I think it is sound. In America, I can continue to receive reports on Aboriginal practices as a basis for my study of the 'primitive' mind, but the indigineous populations in the America's are much more available for first hand study. A loose analogy, but good enough for illustration.

No. We can calculate this exactly, using standard mathematical techniques. No approximation is required.

Are you saying that n-1/n eventually becomes n/n? If you are talking about using elipses to erase the infinite steps then I contend you are wrong given the parameters of the 'halvseys' mathematical setup. If you mean there is a distance between particles where the halving begins to involve an interaction of forces, then you are not talking mathematics, you are in the realm of physical reality.

Such testing is not necessary, because the conclusion that time dilation happens is not derived with reference to any particular physical process.

To state that 'Testing is not necessary' is anti-scientific. This is to say that theories should not be tested. I reject this contention. A theory in physics that is made without any reference to physical processes may or may not be valid, but the theory is meaningless if study and analysis of physical process and the predictions made by the theory do not need to be tested and validated.

When you do a fundamental test of an effect, you look for simple examples with few variables, not an incredibly complicated system where the effect you're looking for is swamped by many other effects

Which is why I contend that local study of relativistic phenomenon is more important. The complexities of the information we receive via light and EM interstellar phenomenon filtered through a multitude of variable interactions is incredibly complex system, wouldn't you agree? I hope someone is willing to get into the light tube gravity experiment..oh yes..yes indeed.

Relativity is an amazing, counter-intuitive theory. Which happens to be right (for all tests so far).

It is counterintuitive in some of its explanations, yes. Its 'rightness' in its various parts are the nature of many people's constant study.

That is incorrect. You're downplaying the insights relativity gives us into the nature of space and time.

To state that this is about measurements is to understand relativity[SR for now]as measurement issues. Here are some folks and their thoughts:
*Pauli, W., Theory of Relativity (1921), Dover 198112-13]:It therefore follows that the Lorentz contraction is not a property of a single rod taken by itself, but a reciprocal relation between two such rods moving relatively to each other, and this relation is in principle observable.
*Eddington, A. S., The Nature of the Physical World , 1928, CUP / MacMillan (NY)33-34]:
"The shortening of the moving rod is true , but it is not really true."
*Taylor, E.F., & Wheeler, J.A., Spacetime Physics: Introduction to Special Relativity, 2nd ed., W.H. Freeman, New York, 1992.]Does something about a clock really change when it moves, resulting in the observed change in the tick rate? Absolutely not! Here is why: Whether a clock is at rest or in motion ... is controlled by the observer. You want the clock to be at rest? Move along with it. ... How can your change of motion affect the inner mechanism of a distant clock? It cannot and it does not. [CRISP-Thanks for the complete reference of this book]
*McCrea, W.H., Relativity Physics, 4th ed., Methuen, London, 195415-16]:The apparent length is reduced. Time intervals appear to be lengthened; clocks appear to go slow.
Minkowski, H., "Space and Time" (1908), in H.A. Lorentz et al., The Principle of Relativity, Dover, 1952,75-91. ][The] contraction is not to be looked upon as a consequence of resistances in the ether, or anything of that kind, but simply as a gift from above, - as an accompanying circumstance of the circumstance of motion.

The range of approaches is astounding. If you claim I am incorrect on the assertion that SR is more about measurements of time, then do you discount Taylor & Wheeler. I will read them in complete context, but their statement appears to clearly state it is an appearance of dilation, no? Should I follow Eddinton's logic: it is true and not true? McCrea's focus on appearances must be downplaying the insights as well. There are more, but that will be for another time.

That's just the way it turns out

..regarding light as an integral part of the formulas of SR. I know you must be speaking facetiously. If you are being serious, then Einstein just accidentally used the speed of light and it just happens to work out and every one goes home saying we understand space and time.

That's what the formula tells us straight out! You only need to read it correctly. It is not about transmission of information. I've already explained why (twice).

Some of the biggies in relativity would disagree with you; this is not just a random opinion held only by yours truly.

In other words, how would you tell if a clock slowed down but "existence" did not? Please give me an example, if you can come up with one. If you can't, I'm afraid you'll have to accept that the rate of "existence" is measured with clocks.

When the shadow on my sundial says it is three o'clock PM and the sun is at its furthest distance from the earth and my battery powered clock says it is 10 AM. The interactions of systems within local and distant frameworks which have been studied mapped and charted over centuries act as good error correcting devices for fallible human clocks. Human-made devices to slice up the passing of time for the convenience of humanity [or enslavement say some.] are astoundingly important to our era, but the position of the heavenly bodies mapped out time for most of our history. In countries that observe daylight savings time, time/existence is not speeded up in spring because the clocks are set forward one hour. If I create a clock with non-standard gear ratios so that the time measurement is slowed down, have I changed the rate of existence? Is it merely the democracy of a majority of timepieces that ensure that a standard existence is metered out? Modern measuring devices are tools that are supposed to be held to a consistent standard. If a clock is slow compared to a standard, this does not necessarily mean that anything has changed but the clock's synchronization to the standard.

Einstein's own words: After ten years of reflection such a principle resulted from a paradox upon which I had already hit at the age of sixteen: If I pursue a beam of light with the velocity c (velocity of light in a vacuum), I should observe such a beam as a spatially oscillatory electromagnetic field at rest. However, there seems to be no such thing, whether on the basis of experience or according to Maxwell's equations. From the very beginning if appeared to me intuitively clear that, judged from the standpoint of such an observer, everything would have to happen according to the same laws as for an observer who, relative to the earth, was at rest. For how, otherwise, should the first observer know, i.e., be able to determine, that he is in a state of fast uniform motion?

It may be too easy to visuallize what a water wave would look like at a standstill, but it is an artificial visualizaton...a visualization of what can not exist. There is no such thing as a spatially oscillatory water wave at rest, either. There can be a standing wave, but this is not at rest. So why is this not a valid slowed down parallel to a beam of light? We are dealing with energy in a waveform. If the waveform seems to be at a standstill, it is either a standing wave, and hence an continuing oscillation, or we are moving at the speed of the wave. Notice how Einstein is speaks of the need for one to determine if he is in a state of fast uniform motion. ***I will endeavor into his germinal ideas more another time***
Q,

Yes. Each twin will view their own clock as ticking normal and will view the other twins clock as ticking slower. Each twin will measure their own rods at one meter and the other twin's rod at (.44) meters. Therefore one twin measures differently than the other relative to their own measurements.

So it is merely a matter of appearances, depending upon their respective positions? If you are saying both realities are true, then you are saying both slowed down and both rods were shortened in an equal measurement, net result is zero.

The OTHER frames, relative to your FOR, will be measured to experience the effects of SR, time dilation and length contraction.

Then you are saying that equivalent relativistic effects equally apply to both FORs? That it is irrelevant which FOR is referenced as the rest FOR?

I'm trying not to hold your hand through the entire explanation but am allowing you to put some of the pieces together yourself. Think it through. I calculate one meter to be one meter from my FOR. For the twin moving at .9c, his meter will measure (.44) of a meter. If the twin travels to the nearest star and back, a distance of about 8 lightyears (75.2 trillion miles), he will have traveled about 3.5 lightyears (33 trillion kilometers).

Implying hand-holding is a clever rhetorical device to lessen my attempts to elicit clarity, but it does not erase the contradictions.
If a star is one light year away, and someone goes .9c, then it will take 1.111111111. The at rest FOR may see the shortening of the moving one's measuring rod, but the mover will not. This is by your own statements. How is someone going slower than the speed of light able to move faster than the speed of light? You give a distance of 8 light years, state that a lightyear is a standard in all frames, yet a slower than light speed traveller moves faster than light to return 4.5 lightyears earlier than a beam of light would take?

When he returns to Earth and the twins compare clocks, the Earth bound twin will have aged more than the moving twin. No paradox.

Again, you have stated that either twin measures the other clock as slowing and the other's rod as shortening. So either twin can meet back up with the other and be the aged one. Paradox intact.

Regards,
137

 

[James R]

137,

Before you can effectively critique a theory you need to understand it. I strongly suggest that you get hold of an introductory text on relativity and learn what relativity actually says. Get a <b>modern</b> book. It is not that Einstein, Minkowski etc. did not know what they were talking about, but we now have the benefit of 100 years of thought on how to best explain relativity to a beginner.

It seems to me that you do not understand the symmetrical nature of relativity. That is a common misunderstanding, shared by some other posters on this forum. Any observer is entitled to consider herself stationary. When she looks at objects moving relative to her, she perceives their time as slowed down and their lengths contracted. They, in turn, perceive her clocks as slow and her lengths contracted.

Now to your reply...

<i>If we can study all of the phenomenon in our local frame and understand all the variables which affect measurements we can more honestly evaluate distant phenomenon.</i>

What if it is harder to study local phenomena than distant ones?

<i>Are you saying that n-1/n eventually becomes n/n?</i>

I'm not sure that there's much point in continuing with this mathematical argument. In the limit as n goes to infinity, n-1/n goes to n/n=1. That is a perfectly adequately defined mathematical process.

<i>To state that 'Testing is not necessary' is anti-scientific. This is to say that theories should not be tested. I reject this contention.</i>

Please re-read what I actually said. I did not assert that testing of relativity is not necessary. What I said was that testing of time dilation for many different physical systems is not necessary - and I explained why.

<i>To state that this is about measurements is to understand relativity[SR for now]as measurement issues.</i>

We can discuss realism vs. instrumentalism if you want to, but that's a philosophical discussion which is really separate from the current discussion of physics. As a physicist, I say that relativistic effects are real. If I pull out my ruler and measure a length, the answer I get relates to a real thing. Same if I use my stopwatch.

<i>Here are some folks and their thoughts:
*Pauli, W., Theory of Relativity (1921), Dover 198112-13]:It therefore follows that the Lorentz contraction is not a property of a single rod taken by itself, but a reciprocal relation between two such rods moving relatively to each other, and this relation is in principle observable.</i>

I agree.

<i>*Eddington, A. S., The Nature of the Physical World , 1928, CUP / MacMillan (NY)33-34]:"The shortening of the moving rod is true , but it is not really true."</i>

If he does not go on to explain this, the statement is meaningless because it is self-contradictory. I suspect he <b>does</b> go on to explain it. Correct?

<i>*Taylor, E.F., & Wheeler, J.A., Spacetime Physics: Introduction to Special Relativity, 2nd ed., W.H. Freeman, New York, 1992.]</i>

I've already said I agree with this.

<i>*McCrea, W.H., Relativity Physics, 4th ed., Methuen, London, 195415-16]:The apparent length is reduced. Time intervals appear to be lengthened; clocks appear to go slow.</i>

I agree.

<i>Minkowski, H., "Space and Time" (1908), in H.A. Lorentz et al., The Principle of Relativity, Dover, 1952,75-91. ][The] contraction is not to be looked upon as a consequence of resistances in the ether, or anything of that kind, but simply as a gift from above, - as an accompanying circumstance of the circumstance of motion.</i>

I agree.

<i>The range of approaches is astounding.</i>

All the approaches are the same, when you understand what these people are talking about.

<i>..regarding light as an integral part of the formulas of SR. I know you must be speaking facetiously. If you are being serious, then Einstein just accidentally used the speed of light and it just happens to work out and every one goes home saying we understand space and time.</i>

I am serious. Einstein started with 2 postulates. If you start with those two postulates, you are inevitably led to the formulae for time dilation, length contraction and all the other relativity formulae. Those formulae turn out to involve the speed of light. That's just the way they turn out. It's an inevitable consequence of the postulates, not an accident. Use those postulates and you'll get those results.

I said:<i>It is not about transmission of information. I've already explained why (twice).</i>
You said: <i>Some of the biggies in relativity would disagree with you; this is not just a random opinion held only by yours truly.</i>

Which "biggies"? References, please. And no, I'm afraid it's not a random opinion, but an educated one.

I asked: <i>how would you tell if a clock slowed down but "existence" did not?</i>

In reply, you gave me a long explanation of some bad clocks. What makes a good clock? Two things:
1. If I make two identical copies of the clock and sit them side by side, their "ticks" will stay synchronised. They will indicate the same passage of time.
2. If I use the clock to measure the time of some set process now and then use it again some time in the future to measure the same process, those times will agree.

If your sundial is not calibrated for different times of the year, it will be a bad clock in the sense of point 2. The human heart is a bad clock in the sense of point 1. Atomic clocks are good in both senses.

<i>In countries that observe daylight savings time, time/existence is not speeded up in spring because the clocks are set forward one hour.</i>

The time intervals measured by clocks during daylight saving are the same. Only how time is designated is changed. The <b>rate</b> which time is measured is agreed between clocks within and outside the daylight saving period, so these clocks are "good" in the sense of point 2, above.

<i>If I create a clock with non-standard gear ratios so that the time measurement is slowed down, have I changed the rate of existence?</i>

This clock would be good in the senses of points 1 and 2. But the measurement of time is not slowed down in this case. What is slowed is the <b>indication</b> of time relative to standard clocks. If I put one of your non-standard gear clocks on a spaceship, the relativistic time dilation formulae would apply to the times measured in non-standard seconds just as much as they apply to times measured in standard-clock seconds.

<i>If a clock is slow compared to a standard, this does not necessarily mean that anything has changed but the clock's synchronization to the standard.</i>

Correct. My point exactly. Which is why time dilation is so interesting. 2 identical standard clocks appear to run at different rates according to an observer. That's nothing to do with the construction of the clocks, but with the nature of time itself.

<i>Einstein's own words: ...If I pursue a beam of light with the velocity c (velocity of light in a vacuum), I should observe such a beam as a spatially oscillatory electromagnetic field at rest. However, there seems to be no such thing, whether on the basis of experience or according to Maxwell's equations....</i>

Which is exactly my summary of what he said in my previous post.

<i>It may be too easy to visuallize what a water wave would look like at a standstill, but it is an artificial visualizaton...a visualization of what can not exist. There is no such thing as a spatially oscillatory water wave at rest, either.</i>

Wrong. If you move along at the same speed as the wave, you'll see crests and troughs in the wave which appear to be at rest relative to you. Walk along next to a crest, and you can "keep pace" with the crest so that the crest is always next to you. You effectively "stop" the apparent forwards motion of the wave by walking along beside it. In contrast, Einstein says you cannot do that for light.

<i>Then you are saying that equivalent relativistic effects equally apply to both FORs? That it is irrelevant which FOR is referenced as the rest FOR?</i>

Yes, that's what he's saying.

<i>Implying hand-holding is a clever rhetorical device to lessen my attempts to elicit clarity, but it does not erase the contradictions.</i>

There are no contradictions. Only apparent contradictions - from your present point of view.

<i>Again, you have stated that either twin measures the other clock as slowing and the other's rod as shortening. So either twin can meet back up with the other and be the aged one. Paradox intact.</i>

It's the "meeting up" which resolves the paradox. In order to meet up, the two twins must re-enter the same reference frame. Once they do that, their observations must coincide, whereas when they are moving relative to each other they can make different observations regarding lengths and times. In the actual "meeting up" process, one of the twins (and only one) must accelerate, which destroys the symmetry between their points of view.

 

[137]

presumed misunderstanding

James R,

Any observer is entitled to consider herself stationary. When she looks at
objects moving relative to her, she perceives their time as slowed down and their lengths contracted. They, in turn, perceive her clocks as slow and her lengths contracted.

I believe my line of questioning and response shows that the implications of symmetry is understood. Your statement that the slowing clocks and contracted lengths are perceptions is the point I am getting at. I have read old and modern relativity treatises. The range of explanations of varied moderns is as convoluted as the tiny list I posted. Many proponents of relativity are more confused that the state you presume me to be in. Einstein's early papers on SR speak for themselves. My attempt to gain response on the implications have been valid. To imply that I need to find a modern book for beginners begs the question.

What if it is harder to study local phenomena than distant ones?

Then you are not studying hard enough. If the formula predicts that the sun bends light, but it is too hard to prove, so you look through thousands of light years of unknown effects upon light, then it is like studying a forest from a mountain top to learn about the pine needle drop radius, when you could study the tree over to your left.

In the limit as n goes to infinity, n-1/n goes to n/n=1. That is a perfectly adequately defined mathematical process.

It never goes to n over n unless you consider a adequately defined process as erasing the troubling -1. I would avoid your line of reasoning myself. It is unjustifiable, either in mathematics or calculus. It approaches zero, but never achieves it.

What I said was that testing of time dilation for many different physical systems is not necessary - and I explained why.

and your original

The argument is a general one to do with space, time and relative motion. Therefore it is generally applicable to any device or system moving in space and time.

Unacceptable limitation on testing. By this reasoning, when the theory of spontaneous generation was promoted, the rotting meat eventually swarmed with maggots, everyone should have applauded and the theory proven. Testing is always necessary. Atomic clocks may be affected differently from light clocks from electronic clocks to mechanical clocks. These are necessary, and desirable tests. To sweep them under the rug is to hide from what may further prove SR as a perfect theory or where it may need to be adjusted. How can you argue with that?

As a physicist, I say that relativistic effects are real. If I pull out my ruler and measure a length, the answer I get relates to a real thing.

Are you saying that your FOR measurements are real and the other twin's measurements are real and that the observed measurements from each reciprocal twin's FOR are real?

I suspect he does go on to explain it.

Anyone have a link to the Eddington piece. If I find a fuller quote, I will post or link it.

All the approaches are the same, when you understand what these people are talking about.

I could expand upon the list. Some of them had long standing arguments and remained in disagreement among themselves. Some believe appearance is the reality. Some say it is merely appearances. This is not a matter of agreement.

It's an inevitable consequence of the postulates, not an accident.

I now understand what you meant. My point is that Einstein did not just happen to plug in light speed as a convenience. He made a conscious decision to use light as the speed limit of the measureable.

What makes a good clock?

So a good clock is one that has to be affected by speed?

Correct. My point exactly. Which is why time dilation is so interesting. 2 identical standard clocks appear to run at different rates according to an observer. That's nothing to do with the construction of the clocks, but with the nature of time itself.

Setting good clock, bad clock aside for now, your statement cover two crucial points you state a] 2 clocks appear to run at different rates according to an observer but it is the nature of time itself. So which is it? Is it the appearance of different rates of time passage or is it actual time passage differences. Are you going the way of the Eddington statement ' it is the appearance of difference, but it is a real difference.'

Einstein says you cannot do that for light.

Please cite the source, so I can get schooled.

In the actual "meeting up" process, one of the twins (and only one) must accelerate, which destroys the symmetry between their points of view.

Well, hot damn if that don't sound like Schrodinger's cat; Open the box and you get the truth and it ruins the whole 'either-or' setup. So in transit there is an illusion, an appearance of symmetry where each one measures time dilation and length shortening of the other as a reality, when in reality only one twin's reality was slowed and shortened in an unseen reality within their own frame but viewed by the other one as an appearance which was actually a reality with the one twin who kept looking in the mirror and getting older while receiving updated photos of the other twin staying the same age. Paradox is resolved.

ciao,
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