My Problems With Relativity

Factual Questions
141

[quote=“These are my own pants, post:140, topic:388750”]

Okay we can both agree the question of which one “moved” is totally subjective and metaphysical…
As has been pointed out the rocket twin changes direction. QUOTE]

You have made two contradictory statements here - the statements “which one “moved” is totally subjective and metaphysical” and “the rocket twin changes direction”, are mutually exclusive. Also, Einstein did not believe the questions were subjective and metaphysical. He built a whole theory on relative movement, and went so far as to “prove” that time dilation, length contraction, and mass increase, were actual occurences in the moving FR.

[QUOTE. However, try this scenario: after a period the twin on Earth drops through a hole which goes directly through the Earth’s centre and where he comes out the other side and stops. This exactly simulates what the rocket bound twin feels when they stop and then turnaround and whilst it may have a significant effect on the GR correction, whatever effect it does have will still be much smaller than the time dilation effect from the standard twin paradox. We can alos adjust the set-up in other ways. QUOTE]

This in no way equates to my scenario, when the rocket twin gradually comes to a halt and changes direction, he is totally unaware of the change and does not feel anything. He is experiencing 1G all the time. The man dropping through the Earth experiences 0G. Please do not set up your own version and ask your own question and then answer that one, answer mine.

[QUOTE. Compare to the cosmological twin paradox of GR. In this both twins start and finish at the same spot and neither twin is subject to acceleration and the spacetime they occupy is (or at least can be made) very symmetric, yet there is a significant time dilation effect due to the asymmetry introduced by something as esoteric as them having different winding numbers in spacetime.[/QUOTE]

Here we have another argument often used to explain the twin paradox, the introduction of an assymetry, although the relatavist does not refer to it as such.

The questions, which one moved and which one was stationary? and what do the clocks show when compared? still have not been answered.

142

it’s not an argument, it’s a fact. If the twins are truly symmetric their cannot be a time dilation effect between them as that would indicate an asymmetry. I’m pointing out where the asymmetry comes from in this situation

I’ve already said that your first question is totally subjective, you’d have to define, in technical terms, what you mean for that question to make any sense.

In answer to your second question: sorry, but if your going to create a reasonably complciated set-up like you have don’t expect others to take the time (and it would be time-consuming especially if we were to include general relativistic effects) to solve it for you. I’ve already told you the qualitive answer which is easy to arrive at with some straight forward arguments.

143

[quote=“These are my own pants, post:142, topic:388750”]

it’s not an argument, it’s a fact. If the twins are truly symmetric their cannot be a time dilation effect between them as that would indicate an asymmetry. I’m pointing out where the asymmetry comes from in this situation

And there we have the crux of the problem. In SRT, the twins are truly symmetrical as they carry on travelling for ever away from each other so the experiment is not falsifiable. They have to be brought together again for the clocks to be compared, and this is where the adherants say the assymmetry comes from, as acceleration was used to turn one around. By using FRs of 1G, there is symmetry.

144

But your thought experiment provided additional accelerations to one and only one of the participants (by rotating the ship)

145

Yes - you’re right.

146

The occupant of the ship is weightless for 2 periods of 60 seconds, and has been pointed out, this can be equalised by arranging for the man on Earth also to be weightless for 2 periods of 60 seconds. The additional accelerations you speak of are sideways forces, which are tiny, and can be equalised by having the chest on Earth also rotated while it is in freefall. Under these cicumstances, both men are undergoing the same accelerations. This objection is therefore null and void.
While I am answering objections, here is another
Quote:Originally Posted by naita (I think)
What’s clear is that the time dilation ‘suffered’ by the rocket ship observer massively outweighs the tiny peturbation caused by general relativstic effects and the rocket ship observer will experince much less time between the start and the end of their journey than is measured on the Earth bound observer’s clock.

The tiny pertubations caused by GR effects in fact add up to 8.72 hours over the year.
I asume this time dilation (suffered by the rocket ship observer) is caused by SRT, and that is what this posting is really about. Gravity and acceleration cause clocks to run slower when increased, and run faster when decreased. Actually that is not quite true, as a pendulum clock does exactly the opposite, but we’ll leave that for now. It is SRT’s prediction of time dilation and length contraction that I have an issue with. I shall now refer you to an address to the Prussian Acamedy of Sciences in 1921 given by A Einstein. In the paragraph starting “Sub specie aeterni” he recants. Recall that both Poincare and Lorentz believed in a “real” time.
It is to be found at :- http://www.relativitycalculator.com/pdfs/einstein_geometry_and_experience_1921.pdf

147

I don’t think the accelerations are tiny, but even if they are, you can’t make them equal on earth and in space, because you need to rotate the person on earth by 360 degrees while he is in so-called free fall, and rotate the person in space by 180 degrees. And this brings up the real catch - the person on Earth is accelerating in a constant direction, while the person in space is accelerated in one direction for a while and then another direction.

148

I have already pointed out how the other FR can undergo the same accelerations.

149

Remember that the Ptolemaic system held sway for 1500 years, before it was replaced by the Corpernicus sytem, which as we all now know is correct.
The brightest physicists etc are all earning their wages on the back of relativity, they are hardly likely to renounce it. It takes a brave man like Professor Dingle to admit there is something wrong with the theory. None of the so called tests of SRT have actually proved it, they have merely failed to disprove it, which is entirely different. For instance, GPS satelites are time corrected by using relativity. Note that this is vague. The relativity used to correct these satelites is in fact not SRT but LET, which is Lorentian relativity, and all satelites are synchronised with the Earth clock. Tom Van Flandern was involved in the development of GPS, read what he has to say on the subject :- http://metaresearch.org/cosmology/gravity/gps-twins.asp

150

See post 147 for my discussion of why the other FR will not undergo the same acceleration.

151

Post 96 provides a link to experimental results that verify GR’s predictions of time dilation on the surface of the earth.

152

You get a ‘twin paradox’ even if you assume no accelerations at all – if, say, you had access to a magical teleportation device, and one twin teleported himself onto a spaceship travelling away from Earth with a certain velocity, then after some time teleports himself onto another spaceship going back towards Earth, and teleports to Earth in the final step, he will have experienced less time passing than somebody staying behind. The real asymmetry comes from switching frames of reference – the moving twin does not inhabit one single frame, as the stationary one does, but must at least (in the case of instantaneous teleportation) occupy two, and infinitely many infinitesimally differing ones in the case of continuous acceleration. So your example is of the same kind, just with a little bit of integration instead of constant velocities. The qualitative conclusion does not change.

Perhaps a few points for clarity: if somebody accelerates at constant g, then, relative to a stationary observer, his time dilation becomes arbitrarily large, because he goes faster and faster, meaning a larger and larger gamma factor. Are we agreed so far?

However, for an observer in a gravitational potential, experiencing 1g, the time dilation relative to an observer far away from the gravitational field stays constant at all times. Again, agreed so far?

So, for the moving observer, his time dilation factor will eventually exceed the one of the observer in the gravitational field, again relatively to a stationary observer far away from any gravitational fields. Still with me?

Now you seem to contend that somehow, reversing direction evens things out again, meaning that if the gravitational-field observer and the moving observer meet, their clocks will agree. Is that what you’re saying?

But this is just the special relativistic twin paradox – as I’ve shown, the GR effect is utterly negligible. Move for some time away from the Earth, move back towards the Earth, in the end, you will have picked up a time delay relatively to the Earth; it’s a completely general conclusion, independent of the particulars of the motion.

Perhaps the picture I offered earlier helps: the observer back on Earth can be, for all intents and purposes, regarded as stationary. Hence, all his motion will be through time, at the speed of light. However, the moving observer also moves through space, so he covers less ground through time.

Viewed another way, it’s really the same as saying that a straight line is the shortest distance between two points; any other curve must be longer. At least, that’s the way it is for Euclidean geometry – in special relativity, things are different in so far as the length of a curve, the proper time, is maximal for an inertial observer. The proper time can be written as dτ = sqrt(dt[sup]2[/sup] - dx[sup]2[/sup] - dy[sup]2[/sup] - dz[sup]2[/sup]), where the ‘d’ means an arbitrarily small change in any of the quantities, τ is the time an observer’s clock measures, t is the time a stationary/far away observer measures, and x, y, z are the usual coordinates. Plainly, τ is maximal (and then, equal to t) if all of dx, dy, and dz are 0 – if there is no motion through space, in other words. Thus, the moving observer must experience less time passing.

Except that a convincing renunciation would likely earn you more wages than a lifetime’s toeing the party line; it’s just that so far, nobody has managed to produce one.

153

[Quote from half man half wit]
Perhaps a few points for clarity: if somebody accelerates at constant g, then, relative to a stationary observer, his time dilation becomes arbitrarily large, because he goes faster and faster, meaning a larger and larger gamma factor. Are we agreed so far?

Definitely not. My argument with SRT is that time dilation is just a visual effect, and is not real. A stick half in and half out of water is “really” bent is it? Did you read Einstein’s adress to the Prussian Acamedy of Sciences? In 1921 he admits the effects are kinematical and not real.

However, for an observer in a gravitational potential, experiencing 1g, the time dilation relative to an observer far away from the gravitational field stays constant at all times. Again, agreed so far?

This one is true, providing both observers use clocks of the same construction.

So, for the moving observer, his time dilation factor will eventually exceed the one of the observer in the gravitational field, again relatively to a stationary observer far away from any gravitational fields. Still with me?

“Still with me?” is patronising. Don’t do it. I am disagreeing with you. Kinematical only.

Now you seem to contend that somehow, reversing direction evens things out again, meaning that if the gravitational-field observer and the moving observer meet, their clocks will agree. Is that what you’re saying?

I have never said that changing direction evens things out, the man in the chest in the rocket is completely unaware of any change in direction, and according to the principle of relativity (which I have no great argument with), he is entitled to say that he has been stationary the whole time.

But this is just the special relativistic twin paradox – as I’ve shown, the GR effect is utterly negligible. Move for some time away from the Earth, move back towards the Earth, in the end, you will have picked up a time delay relatively to the Earth; it’s a completely general conclusion, independent of the particulars of the motion.

Same as point 2. Yes providing as above the clocks are identical in construction.

Perhaps the picture I offered earlier helps: the observer back on Earth can be, for all intents and purposes, regarded as stationary. Hence, all his motion will be through time, at the speed of light. However, the moving observer also moves through space, so he covers less ground through time.

But equally, the man in the rocket can also be regarded as stationary, while the man on Earth moves through space. Remember they are alone in the universe (or far enough away from other bodies as to be effectively so).

154

Well, then you’re in disagreement with well established experimental results – as has been pointed out, moving clocks indeed pick up a time delay relatively to stationary ones. This is as real an effect as any. Of course, one may regard relativity as emergent, the way it’s done in condensed matter systems, where the relativistic effects are due to a maximum speed of the probes you use within the medium, even though viewed from an exterior frame, the whole situation is effectively Newtonian – in fact, Bell advocated teaching SR from this viewpoint (referring to it as ‘Lorentzian pedagogy’). But it’s physically completely equivalent (at least at low energies) to ‘fundamental’ special relativity, so the effect is equally real in both cases; and of course, arguing for an external space and time for the universe is disfavored from an Occam’s razor point of view wrt a Minkowskian spacetime.

Why do you think the construction of the clock matters?

No. The turning around will lead to observable effects; effectively, he changes inertial frames. There is no single inertial frame of reference that describes the motion of the rocket at all times, but there is one for the stationary observer.

Still, the man in the rocket changes reference frames – he must, or he could not get back to Earth. In this regard, both observers aren’t equivalent.

155

Once again, no.

Rather than putting humans through the trauma of being shut in boxes for a year, put in an accelerometer (Accelerometer - Wikipedia) and some gyroscopes (Gyroscope - Wikipedia) to keep the accelerometer at a constant orientation. These are strictly local devices that work without sensing anything outside the boxes.

For the box on Earth, the accelerometer reads 1g throughout, except for the brief period when the box is somehow made weightless (and there are problems with that idea - after a minute of free fall, the box would be moving very fast relative to the Earth, so how do you stop it without extreme accelerations). The gyroscopes keep the accelerometer pointing in the same direction even as the whole box is rotated 360 degrees around the accelerometer.

For the box in space, the first half of the trip looks just the same as what happens on Earth. But when the box is rotated 180 degrees, the gyroscopes detect that, and register the fact that the acceleration is now negative 1 gee for the rest of the trip - a pretty significant asymmetry.

156

You don’t even need instantaneous teleportation. Imagine a spaceship moving past Earth at a constant speed. Have the observers on Earth (observer “E”) and the spaceship (observer “A”) synchronize clocks at the moment that the ship is closest (arbitrarily close) to the Earth. As some future point, the spaceship encounters a spaceship (containing observer “B”) which is moving towards Earth. Have observer “B” synchronize with “A” when the two spaceships are arbitrarily close to each other. When “B” gets to Earth, its clock will be behind the one on Earth.

157

I can’t answer all objections, but here are some :- A magical teleportation device infers communication at faster than light speed. You cannot argue for and against faster than light communication.

The swapping twins trick is one of two things, either synchronisation between fast moving FRs, or instantaneous transportation, neither of which are allowed.

Yes the gyroscopes register the rotation of the chest, but the Earth is rotating, and the 1G on Earth, when looked at from another FR, goes from +1G to -1G and back again in 24 hours. That assymetry is not noticed and does not affect anything on Earth, so it does not affect anything for the man on the rocket.

“The turning around will lead to observable effects; effectively, he changes inertial frames.” He is in a closed chest, he has no reference points, he does not know he has turned round.

The phrase “construction of the clock” was used by Einstein to mean identical clocks ie they keep identical time and stay synchronised when in the same environment. (That is simplified, for the full explanation read what Einstein has to say).

Moving clocks in the Earth’s atmosphere do indeed undergo a time dilation effect, but is this caused by pure velocity or by other effects such as the local gravitational field? The Hafele-Keating experiment was seriously flawed.

I notice no references to either Einstein’s adress to the Prussian Acadamy of Sciences, or to Tom Van Flandern’s page. Does anybody care to comment?

158

The point is: one inertial reference frame, in which the observer back on Earth is stationary, describes his motion at all times. The same is not true for the moving observer. In the case of constant velocity, we need at least two: one going at the speed v away from the Earth, the other going at speed -v back towards Earth. The case involving acceleration needs an infinite succession of reference frames, starting at one stationary with respect to the Earth, then one moving at an infinitesimal velocity dv, then one moving at an infinitesimally higher velocity dv + dv, and so on, up to one moving at velocity v, where the deceleration begins, and you need an infinitesimally slower frame v - dv, then a yet slower one, until you are again ‘at rest’ wrt Earth, when you begin accelerating back towards Earth, starting with a reference frame moving at -dv, and so on, until you move towards Earth at -v, then once again start to slow down, i.e. going to a reference frame -v + dv, and so on, until you arrive stationary wrt Earth at v = 0. These frames have to be integrated over; the conclusion, however, is of course the same as it is in the (unphysical) case where you approximate the whole thing using only two frames of reference.

By both, of course. A simpler demonstration is given by moving elementary particles, for instance myons: they are produced in the upper atmosphere, and live for around 2.2 microseconds; this would allow them to travel about 660 m, if they traveled at lightspeed (which they don’t, of course). So, none of them would be detected at ground level. Yet, we do in fact detect myons at ground level – due to relativistic time dilation, their high speed means that they get to ground level such that less than 2.2 microseconds have elapsed on their internal clocks.

What, in particular, do you feel needs to be commented on?

159

In the above post, ‘myons’ should be ‘muons’, of course – I accidentally used the German word.

160

It doesn’t matter that the asymmetry isn’t noticed by the man, the universe doesn’t care about the threshold of human perception. What matters is that the two situations are a s y m m e t r i c, and that the effects of the twin “paradox” can be wholly explained by SR.

And unless you want to argue for the impossibility of making clocks of the same construction, synchronizing clocks between moving reference frames is no problem. I make three clocks, move them to appropriate starting points for the time swapping scenario, and then interchange information about their state at the appropriate points in space. We can even run both space ships at 1G if that makes you happy. Travel time for leaving and returning will end up shorter than time measured for the “stationary” observer.

If your problem is “fast moving frames” we can run the experiment with lower speeds and shorter distances, all we need is clock accuracy.