Room-temperature superconductivity?

[Teahive]

If these two statements are true:

1) The relativistic doppler shift of electromagnetic waves is an actual, observable phenomenon.
2) The SI definition of a second – being the duration of 9,192,631,770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the cesium 133 atom, with the atom at rest relative to the observer – is valid for every observer in the universe.

it logically follows that time dilation is a real, observable effect. You don't even require a returning twin to show this. And since 2) is a definition, you really only need experimental proof of 1).

Travel between two planets

Two planets, A and B, are 6 lighyears apart. They both have identical cesium atomic clocks which not only count the periods of the radiation emitted from a cesium atom, but also amplify and broadcast the signal into space, so that it can be counted by any other observer. Both clocks are synchronised using Einstein's method, thus as A and B communicate and tell each other the time, they both always agree that they receive signals which were sent 6 years ago.

Now, a spaceship S with an identical atomic clock departs A at time t = 0 and rapidly accelerates to v = 0.6 c. The relativistic doppler factor for an emitter approaching at this speed along the line of sight is squareroot((1 + 0.6) / (1 - 0.6)) = 2. The doppler factor for a departing emitter is 1/2.

Of course A sends a report of the departure of the spaceship to B. This news arrives 6 years later. After 10 years the spaceship arrives, and news of this event is equally sent back to A, where the message arrives 16 years after the spaceship's departure.

An observer on B records these events

• At t = 6, news of S leaving A arrives
• At t = 10, S arrives on B

Between these two events, observers on B receive 4 years worth of time signals from A. During the same time they receive 4 * 2 = 8 years worth of time signals from S due to the doppler shift. They must therefore conclude that the clock on S counted 8 years elapsing during the flight. However they must also conclude that S departed A at t = 0, i.e. 10 years ago, due to the known transmission delay between A and B.

An observer on A records these events

• At t = 0, S departs from A.
• At t = 16, news of the arrival of S on B comes in

Between t = 0 and t = 16, observers on A receive 16 years worth of time signals from B. During the same time they receive 16 * 0.5 = 8 years worth of time signals from S. They, too, must therefore conclude that the clock on S counted 8 years elapsing during the flight. However they must also conclude that S took 10 years to arrive on B due to the known transmission delay between A and B.

Both observers on A and B thus agree that it took S 10 years to travel, but that the clock on S would only have counted 8 years elapsing.

[D Tibbets]

If anyone wants to actually see some arguments/ references on this debate from outside of the Talkpolywell forum:

http://www.npl.co.uk/upload/pdf/metromnia_issue18.pdf

http://www.conspiracyoflight.com/Gravit ... ation.html


Two quotes from the following site. The first shows some of the consequences of different relativistic speeds. The second one gives multiple references of experiments done.

http://www.scienceforums.net/topic/3420 ... over-time/

"Janus

"Atom


plane is in the air touchING down the clock would show retarding in relation to the static clock aboard the plane that already landed and would show the same time when they met up.Einstein is wrong.I am sorry."


"Sorry, no. This can be shown by considering two ships flying to Alpha Centauri. 1 at .866c and the other at .1c

The first takes 4.96 yrs Earth time to make the trip and records the trip as taking 2.48 years.

The second takes 43 years Earth time and records the trip as taking 42.78 years.

So when the first ship arrives it reads 2.48 yrs and the second ship has traveled 4.96 yrs of its 43 year long trip. Thus the first ship's clock will record an addtional 43-4.96 = 38.04 years while waiting for the second ship to arrive and will read a total of 38.04+2.48 = 40.52 yrs when the second ship arrives. As noted above, the second ship's clock records 42.78 years upon arrival, so there will be a 2.26 year difference between the clocks.

The same would be true of clocks in planes flying around the world at different speeds; the clocks would differ in the end."

"Copernicus_Meme



"Harlequinne said:
Impossible.If two planes flew around the world at different speeds,one touches down first it shows a retarded time.By the same logic the rates the clocks move while the other plane is in the air touchING down the clock would show retarding in relation to the static clock aboard the plane that already landed and would show the same time when they met up.Einstein is wrong.I am sorry."


"Impossible? On the contrary, validated up the yin yang so to speak.

Here are a few sources on the experimental basis of SR (that's Special Relativity);

The Michelson and Gale Experiment (Nature 115 (1925), pg 566; Astrophys. J. 61 (1925), pg 137.)
g−2 Experiments as a Test of Special Relativity: Newman et al., Phys. Rev. Lett. 40 no. 21 (1978), pg 1355. P.S. Cooper et al., Physical Review Letters 42 (1979), pg 1386. Farley et al., Nuovo Cimento Vol 45, pg 281 (1966). Bailey et al., Nuovo Cimento 9A, pg 369 (1972). Bailey et al., Phys. Lett. 68B no. 2 (1977), pg 191.
The Brookhaven experiment to measure g−2 for muons, http://www.g-2.bnl.gov/
The Fizeau Experiment: Bilger et al., Phys. Rev. A5 (1972) pg 591. James and Sternberg, Nature 197 (1963), pg 1192.
Particle-Based Experiments: Nguyen, H.H., “CPT results from KTeV”, (2001). arXiv:hep-ex/0112046. Schwingenheuer, B. et al., “CPT tests in the neutral kaon system”, Phys. Rev. Lett., 74, pg 4376–4379, (1995). Carey, R.M. et al., “New Measurement of the Anomalous Magnetic Moment of the Positive Muon”, Phys. Rev. Lett., 82, pg 1632–1635, (1999). (Reinhardt's Ph.D. thesis, 2005)
Calorimetric Test of Special Relativity: .R. Walz, H.P. Noyes and R.L. Carezani, Physical Review A29 (1984), pg 2110.
Twin Paradox: C. Alley, “Proper Time Experiments in Gravitational Fields with Atomic Clocks, Aircraft, and Laser Light Pulses,” in Quantum Optics, Experimental Gravity, and Measurement Theory, eds. Pierre Meystre and Marlan O. Scully, Proceedings Conf. Bad Windsheim 1981, 1983 Plenum Press New York, ISBN 0-306-41354-X, pg 363–427. Bailey et al., “Measurements of relativistic time dilation for positive and negative muons in a circular orbit,” Nature 268 (July 28, 1977) pg 301.
Doppler Shift Measurements: McGowan et al., Phys. Rev. Lett. 70 no. 3 (1993), pg 251. Olin et al., Phys. Rev. D8 no. 6 (1973), pg 1633. Mandelberg and Witten, Journal Opt. Soc. Amer. 52, pg 529 (1962).
Measurements of Particle Lifetimes: D. Frisch and J. Smith, “Measurement of the Relativistic Time Dilation Using Mesons”, Am. J. Phys. 31 (1963) 342. Ayres et al., Phys. Rev. D3 no. 5 (1971), pg 1051.
The Ives and Stilwell Experiment: H.E. Ives and G.R. Stilwell, “An Experimental Study of the Rate of a Moving Atomic Clock”, J. Opt. Soc. Am. 28 pg 215–226 (1938); JOSA 31 pg 369–374 (1941).
Other Experiments: Coleman and Glashow, “Cosmic ray and Neutrino Tests of Special Relativity”, Coleman and Glashow, “High-Energy Tests of Lorentz Invariance”
The Trouton-Noble Experiment: Tomaschek, Ann. d Phys. 78 (1926), p743; 80 (1926), pg 509.
Zhang, "Special Relativity and its Experimental Foundations".
The Kennedy-Thorndike Experiment
Wolf and Petit, “Satellite test of special relativity using the global positioning system”, Phys. Rev. A 56, p4405 (1997).


http://math.ucr.edu/...xperiments.html

A couple of more articles:
*Relativity in the Global Positioning System

http://www.physorg.com/news9248.html "

Dan Tibbets

[CaptainBeowulf]

That applies to anyone else on this thread. Where does what I have said, in my critique of Johan, state or imply that clocks keep different rates in their rest frames, or that time rate changes with position?

I don't think anything you've said implies that. You present the generally accepted position that the proper time that elapses along different paths through spacetime is different. This is what Johan seems to reject. I think the discussion gets muddied by the limitations of English (and probably any other) language... as language evolved to express pre-Newtonian, and at best Newtonian, interpretations of time and space. Mathematics is probably the clearest "language" for the finer points of the discussion because English gets confusing.

[GIThruster]

I think the discussion gets muddied by the limitations of English (and probably any other) language... as language evolved to express pre-Newtonian, and at best Newtonian, interpretations of time and space. Mathematics is probably the clearest "language" for the finer points of the discussion because English gets confusing.

Einstein preferred English. Thus isn't a misunderstanding. Johan believes Einstein and basically everyone since over these last 100 years, has been wrong, where he alone is right, and he wants to correct us all.

[tomclarke]

That applies to anyone else on this thread. Where does what I have said, in my critique of Johan, state or imply that clocks keep different rates in their rest frames, or that time rate changes with position?

I don't think anything you've said implies that. You present the generally accepted position that the proper time that elapses along different paths through spacetime is different. This is what Johan seems to reject. I think the discussion gets muddied by the limitations of English (and probably any other) language... as language evolved to express pre-Newtonian, and at best Newtonian, interpretations of time and space. Mathematics is probably the clearest "language" for the finer points of the discussion because English gets confusing.

It is a geometric point. The path-length is different. Johan cannot (conceptually) admit this. So in his world the "time rate" must be different even though this does not make any sense.

You are right that English is very misleading. I have always had a mathematical view of what is going on, which throughout this thread has got sharper - there is nothing like continual argument to encourage better understanding. The words I use here are just different attempts to make this understanding clear to others.

[tomclarke]

There are in fact very few references out there which tackle properly the twins paradox. Tom van Flandern is one of the few which addresses the matter in detail. It requires just a bit more maths than is easy to cut into byte-sized chunks.

The argument that because time dilation is symmetrical between two moving frames there can be no elapsed time difference between the twins is number 1 misconception. Johan extends this, logically, to say that time dilation is not real - but then he encounters other problems.

Number 2 misconception is that the asymmetry between the twins which causes the asymmetry in proper time must be the acceleration. If you accept this you can then easily show that acceleration times can be reduced and clocks don't change much during acceleration, so it has minial effect. Also there is experimental evidence that acceleration does not alter clocks.

The resolution of the paradox is then the idea that changing frame alters the (local frame) time of distant clocks. This effect is large and asymmetric in the twins paradox.

When thinking about these matters it is easy to implicitly assume some unique global time measure. "At the same time" does this. Of course, "At the same time" can be defined throughout spacetime, it is just that the definition is dependent on the rest frame in which it is done. Johan is very prone to "at the same time" arguments without specifying frame.

When I started this debate I had only a very fuzzy idea about all these issues, so I knew Johan was wrong because his claims were contrary to experiment and some of the things he was saying did not make sense, but I did not have a complete answer to all his points.

I think they have all now been covered in detail.

[tomclarke]

If anyone wants to actually see some arguments/ references on this debate from outside of the Talkpolywell forum:

http://www.npl.co.uk/upload/pdf/metromnia_issue18.pdf

http://www.conspiracyoflight.com/Gravit ... ation.html


Two quotes from the following site. The first shows some of the consequences of different relativistic speeds. The second one gives multiple references of experiments done.

http://www.scienceforums.net/topic/3420 ... over-time/

"Janus

"Atom


plane is in the air touchING down the clock would show retarding in relation to the static clock aboard the plane that already landed and would show the same time when they met up.Einstein is wrong.I am sorry."


"Sorry, no. This can be shown by considering two ships flying to Alpha Centauri. 1 at .866c and the other at .1c

The first takes 4.96 yrs Earth time to make the trip and records the trip as taking 2.48 years.

The second takes 43 years Earth time and records the trip as taking 42.78 years.

So when the first ship arrives it reads 2.48 yrs and the second ship has traveled 4.96 yrs of its 43 year long trip. Thus the first ship's clock will record an addtional 43-4.96 = 38.04 years while waiting for the second ship to arrive and will read a total of 38.04+2.48 = 40.52 yrs when the second ship arrives. As noted above, the second ship's clock records 42.78 years upon arrival, so there will be a 2.26 year difference between the clocks.

The same would be true of clocks in planes flying around the world at different speeds; the clocks would differ in the end."

"Copernicus_Meme



"Harlequinne said:
Impossible.If two planes flew around the world at different speeds,one touches down first it shows a retarded time.By the same logic the rates the clocks move while the other plane is in the air touchING down the clock would show retarding in relation to the static clock aboard the plane that already landed and would show the same time when they met up.Einstein is wrong.I am sorry."


"Impossible? On the contrary, validated up the yin yang so to speak.

Here are a few sources on the experimental basis of SR (that's Special Relativity);

The Michelson and Gale Experiment (Nature 115 (1925), pg 566; Astrophys. J. 61 (1925), pg 137.)
g−2 Experiments as a Test of Special Relativity: Newman et al., Phys. Rev. Lett. 40 no. 21 (1978), pg 1355. P.S. Cooper et al., Physical Review Letters 42 (1979), pg 1386. Farley et al., Nuovo Cimento Vol 45, pg 281 (1966). Bailey et al., Nuovo Cimento 9A, pg 369 (1972). Bailey et al., Phys. Lett. 68B no. 2 (1977), pg 191.
The Brookhaven experiment to measure g−2 for muons, http://www.g-2.bnl.gov/
The Fizeau Experiment: Bilger et al., Phys. Rev. A5 (1972) pg 591. James and Sternberg, Nature 197 (1963), pg 1192.
Particle-Based Experiments: Nguyen, H.H., “CPT results from KTeV”, (2001). arXiv:hep-ex/0112046. Schwingenheuer, B. et al., “CPT tests in the neutral kaon system”, Phys. Rev. Lett., 74, pg 4376–4379, (1995). Carey, R.M. et al., “New Measurement of the Anomalous Magnetic Moment of the Positive Muon”, Phys. Rev. Lett., 82, pg 1632–1635, (1999). (Reinhardt's Ph.D. thesis, 2005)
Calorimetric Test of Special Relativity: .R. Walz, H.P. Noyes and R.L. Carezani, Physical Review A29 (1984), pg 2110.
Twin Paradox: C. Alley, “Proper Time Experiments in Gravitational Fields with Atomic Clocks, Aircraft, and Laser Light Pulses,” in Quantum Optics, Experimental Gravity, and Measurement Theory, eds. Pierre Meystre and Marlan O. Scully, Proceedings Conf. Bad Windsheim 1981, 1983 Plenum Press New York, ISBN 0-306-41354-X, pg 363–427. Bailey et al., “Measurements of relativistic time dilation for positive and negative muons in a circular orbit,” Nature 268 (July 28, 1977) pg 301.
Doppler Shift Measurements: McGowan et al., Phys. Rev. Lett. 70 no. 3 (1993), pg 251. Olin et al., Phys. Rev. D8 no. 6 (1973), pg 1633. Mandelberg and Witten, Journal Opt. Soc. Amer. 52, pg 529 (1962).
Measurements of Particle Lifetimes: D. Frisch and J. Smith, “Measurement of the Relativistic Time Dilation Using Mesons”, Am. J. Phys. 31 (1963) 342. Ayres et al., Phys. Rev. D3 no. 5 (1971), pg 1051.
The Ives and Stilwell Experiment: H.E. Ives and G.R. Stilwell, “An Experimental Study of the Rate of a Moving Atomic Clock”, J. Opt. Soc. Am. 28 pg 215–226 (1938); JOSA 31 pg 369–374 (1941).
Other Experiments: Coleman and Glashow, “Cosmic ray and Neutrino Tests of Special Relativity”, Coleman and Glashow, “High-Energy Tests of Lorentz Invariance”
The Trouton-Noble Experiment: Tomaschek, Ann. d Phys. 78 (1926), p743; 80 (1926), pg 509.
Zhang, "Special Relativity and its Experimental Foundations".
The Kennedy-Thorndike Experiment
Wolf and Petit, “Satellite test of special relativity using the global positioning system”, Phys. Rev. A 56, p4405 (1997).


http://math.ucr.edu/...xperiments.html

A couple of more articles:
*Relativity in the Global Positioning System

http://www.physorg.com/news9248.html "

Dan Tibbets

And, you must not forget somone who provided a very detailed and correct analysis of the twins paradox, now tragically dead:
http://metaresearch.org/cosmology/gravity/gps-twins.asp

[johanfprins]

Well if you admit that time rate within each inertial reference frame is the same, and you admit that time rate does not change with position, then you must admit that you do not have a space-time manifold within which you can generate infinitessimal space-time connections ds=dx-d(ict).

Not at all. The "time rate" of a clock is defined by integrating ds along the clock path. That is local frame time.

This is alo true for Newtonian space.

Einstein's postulate says that e.g. photons from caesium electron bandgap should have constant frequency in every frame.

Correct, so all clocks MUST keep the same time within ALL inertial reference frames.

Well of course they do, because for each frame time is defined by local clocks (e.g. caesium clocks)! It is tautologically true.

AND ALL CLOCKS ARE LOCAL CLOCKS! Therefore time cannot vary from one position in space to another position as it must to be an actual fourth coordinate as in the case of gravity.

Now, coordinate transformations, such as the Lorentz transformation, relate coordinates in one frame to those in another.

Not so in this case. To do this both the position and time must act as actual coordinates when you make the transformation. In other words, ONLY when transformed times at different positions within an inertial refrence fame, give simultaneously different times on the different clocks at these different positions can the transformed time be considered as actual coordinates. This is NOT the case for the Special Theory of Relativity.

For example, when you have a row of stationary light sources within one inertial reference frame and switch them all on simultaneously (for this to happen the clocks at the positions of the light sources must at that instance show exactly the same times), you will see them switching on at different times within a passing inertial reference frame. THIS DOES NOT MEAN THAT THE CLOCKS AT THESE DIFFERENT TRANSFORMED POSITIONS SHOW DIFFERENT TIMES AS THEY MUST IF TIME CAN BE CONSIDERED AS A COORDINATE. It actually means that the clocks at the transformed positions still show exactly the same time as the clocks are showing at different positions within the reference frame within which the light sources have been switched on simultaneously. The fact that the lights are observed to switch on at different times, does not mean that clocks at different positions show different times; and does thus not mean that time is now a fourth coordinate as in the case when graviity is present. The incontrovertible fact is that the clocks at all positions within ALL inertial reference frames can ALL be synchronised to ALL show the exact same time, and therefore time is not a coordinate transformation when applying the Lorentz transformation: This is alo as demanded by Einstein's first postulate.

Einstein's 1st postulate can say little about this relationship, because it has no bearing on whether Newtonian physical laws are identical in every frame, since tehse are defined according to the local frame only.

Absolute BS!! The Lorentz transformation also applies to Newtonian physical laws and Einstein's first postulate is thus applicabkle tol ALL Mechanical and Electrodynamical laws. Newton's laws extrapolate directly from the Lorentz transformation when the speed v becomes small. This does not mean that you have to put v^2/c^2 equal to zero when you do modelling at low speeds; but it becomes convenient to do so. This is so since, at any instant in time t on any of the clocks, the same time t must show on all the other clocks at any and at every spatial position everywhere, whether the relative speed is high or low does not matter: Time can thus not be a separate coordinate as it is when gravity is present.

All you have is a 4D manifold.

Wrong! If you had an actual 4D manifold that is ALSO physically valid as a 4D manifold, then clocks at different positions within space will keep different times. This is NOT the case for SR since all the clocks are keeping the exact same time in this case; just as in the extrapolated case of the same transformation when the relative speed becomes low. As far as time is concerned there is no difference for low and high relative speeds.

ame and therefore your definition of events hapenning on a spatial slice ("any and every spatial position everywhere") is ambiguous.

What is ambigious about it?

Which spatial slice? (Each frame defines a different set of spatial slices).

The spatial slice at time t, since the time coordinate ict is then at every spatial position within every inertial refrence frame perpendicular to the space coordinates; just as it always is for all relative speeds whether low (Newtonian) or very high (Einsteinian).

Your statement is puzzling. On such a 3d spatial surface dt=0 by definition, regardless of dx,dy,dz.

Exactly!

Otherwise all 4 differentials are unrelated - because by definition they are independent.

This also true for Newtonian space: There is no reason why you should only choose t as a fourth coordinate when reference frames move at high velocities relative to one another. So also in Newtonian space you can write that ds=dx+icdt if you want to. And also in this case, for the time does not change from one position to the other; just as in the case when the relative speed is high.

I can't see anything here that prevents a LT from being the correct transformation between one local frame an another.

I have not said it is incorrect but that the assumption that the Lorentz transformation causes the time at different positions to be different is incorrect. Your claim that in this case "global time is not defrined" is paranormal metaphysics.

Maybe Johan should suggest some simple experiment which is ruled by physical laws, and show how the standard LT mapping between frames requires the experimental results to be different in different frames.

I have not claimed that the LT transformation requires that different experimental results must be different within different refrence frames. In fact it is YOU who claims this by arguing that two twins will age at different rates within two identical inertial reference frames.

Johan does not see that physics is defined relative to local time. The fact that local time in one frame is dilated when transformed to a different frame does not mean that it "keeps a different rate".

It does not mean that the dilated time is occurring on the clock from which it is being transformed either. So you must thus agree that the twins MUST stay the same age?

By definition clocks define "the rate" in any local frame. Einstein's postulate says nothing about the transformed times.

Oh yes it does. It tells you that when you tranform the coordinates of the same experiment being done simultaneously within two inertial reference frames from one frame to the other in both directions, you will see the same change in position and time-intervals. This demands that the transformed time intervals must be the same and that therefore the two clocks are keeping the exact same time: The twins can thus not age differentially as you claim that they can.

[johanfprins]

So to argue that according to SR two twins will age at different rates while their clocks are keeping the exact same time on the outward (away from one another) as well as the inward (towards one another) journeys is obviously WRONG. And as I have pointed out time and again, if they have different ages, this will violate Einstein's first postulate; and thus invalidate his whole Special Theory of Relativity.

Forgive me Johan, your argument quoted in my post above does not hold water for the reasons I've given. Other than that argument, did you have any reason for making these two statements? You have indeed repeated them many times.

AND I HAVE GIVEN YOU MANY MANY PROOFS THAT THEY ARE CORRECT! HAVE YOU GOT A READING PROBLEM? DYSLEXIA MAYBE?

I told you what you have to do: The two twins synchronise their clocks when they depart at a a relative speed v. Every second on each of their clocks each twin sends out a light pulse to the other twin and when these light pulses arrive at the other twin respectivly they are recorded. You will find that in order to avoid an absurd situation to occur, the twins must measure the same time difference between sending out a light pulse and recieving a light pulse from the other twin

At some point when sending out its Nth light pulse a twin proceeds back with a relative speed v while both keep on sending light pulses. When they meet up, they will both have sent the exact same number of light pulses and must be the exact same age.

MAYBE YOU CANNOT, OR WILL NOT, do this simple mathematics: But stop accusing me that I am not backing up my statements with proof. And REAL PROOF: Not by arguments based on a physically non-existent space-time manifold as you are doing.

Another argument I already gave is that after a time t on twin1's clock twin2 is a distance D=v*t away from twin1. An after a time tp on twin2's clock he is a distance Dp=v*tp away from twin1. Since one twin1 cannot be further away from twin2 that twin2 is from twin 1, the corresponding time on twiN2's clock when the time on trwin1's clock is t, is THUS given by setting D=Dp; and this gives that t=tp ALL THE WAY OUT AND BACK.

. The twins do not, technically, age at different rates. It is just that one experience more time than the other between when they first meet and next meet.

PARANORMAL CLAPTRAP.

You have never addressed the question of why Einstein's postulate should make two different paths through spacetime have the same elapsed time, as you claim?

Because there are not two different paths through spacetime for the two twins. The path distance and times on the clocks of the two twins are exactly the same within both reference frames ALL THE TIME. THAT IS WHY!

The analogy would be two different great circle paths on the earth's surface between two points having the same distance. Of course there are always two GC paths between two points, of differing distances. That geometric fact does not in any way alter the local properties of distance on the earth.

This is not a good analogy since this analogy is only valid when you have curved space-time: i.e AS I HAVE POSTED A ZILLION TIMES" WHEN THERE IS GRAVITY!!! For crying out loud!

[johanfprins]

I don't think anything you've said implies that. You present the generally accepted position that the proper time that elapses along different paths through spacetime is different.

I know this standard interpretation and as I have stated time and again, to my shame I have taught this to my students.

This is what Johan seems to reject.

Yes I do,since there is not two different "space-times" that is being followed by the twins when there is no gravity.

I think the discussion gets muddied by the limitations of English (and probably any other) language... as language evolved to express pre-Newtonian, and at best Newtonian, interpretations of time and space.

My English is not as bad as this. I know Newtonian physics, and also now know that as far as paths through spacew are concerned the time compoanent is exactly the same at low speeds as at high speeds, when we use the Einsteinian formulas.

Mathematics is probably the clearest "language" for the finer points of the discussion because English gets confusing.

Can you not understand it when I state that the distance of twin2 from twin1 when the time on twin1's clock is t must be D=v*t? And can you not understand that when the time on twin2's clock is tp, the distance of twin1 from twin2 must be Dp=v*tp. And is it impossible for you to look along the x axis and -xp axis and to see that at any instant in time t on twin1's clock the distance of twin1 from twin 2, MUST be the same as the distance of twin2 from twin1? And can you thus not undserstand that this requires from the mathematics that v*t must be eqaul to v*tp? And can you not understand that for any time t you muststhus have that v*t=v*tp. And can then not do the mathematics to reach the conclusion that t=tp ALWAYS?. Can you then not understand that proper time does not manifest when there is no gravity and that therefore the standard mainstream arguments on the twins paradox has been all along nonsense? Did I neglect the mathematics here, or do you not follow when the mathematics is simple and straightforward?

[johanfprins]

You are right that English is very misleading. I have always had a mathematical view of what is going on, which throughout this thread has got sharper - there is nothing like continual argument to encourage better understanding. The words I use here are just different attempts to make this understanding clear to others.

I think that you have been tying yourself in knots. Is it too difficult to understand that when D=v*t and Dp=v*tp, and that D=Dp one must have that t=tp?

[tomclarke]

I told you what you have to do: The two twins synchronise their clocks when they depart at a a relative speed v. Every second on each of their clocks each twin sends out a light pulse to the other twin and when these light pulses arrive at the other twin respectivly they are recorded. You will find that in order to avoid an absurd situation to occur, the twins must measure the same time difference between sending out a light pulse and recieving a light pulse from the other twin

At some point when sending out its Nth light pulse a twin proceeds back with a relative speed v while both keep on sending light pulses. When they meet up, they will both have sent the exact same number of light pulses and must be the exact same age.

That is what you said before. If you remember, I replied that there was no reason why the two twins should send out the same number of pulses over the period, although true that the number received would be the number transmitted.

The asymmetry comes from the fact that inbound and outbound reception of pulses is quite different, due to doppler shift.

The number of pulses received by the travelling twin during the outbound journey is therefore much less than the number transmitted by the travelling twin during the outbound journey. Thus the stationary twin will receive more pulses at a lower frequency (at the rate determined by the outbound velocity) than the travelling twin.

Johan, it is necessary to be very careful when making these arguments for symmetry. In this case you have not been so.

This is not a good analogy since this analogy is only valid when you have curved space-time: i.e AS I HAVE POSTED A ZILLION TIMES" WHEN THERE IS GRAVITY!!! For crying out loud!

It is also true in flat space-time when the metric is non-Euclidean, as here (technically it is not even a metric!).

[johanfprins]

When I started this debate I had only a very fuzzy idea about all these issues,

You are now even more fuzzy than you were in the beginning.

so I knew Johan was wrong because his claims were contrary to experiment

Which experiment?

and some of the things he was saying did not make sense,

Like what? Does it make more sense to say that two twins who experience the same time rate will age at different rates? Are you really serious?

but I did not have a complete answer to all his points.

You still do not have.

I think they have all now been covered in detail.

Well I hope you enjoy your stay in Cloud Cuckoo land my friend!

Best wishes,
Johan

[tomclarke]

You are right that English is very misleading. I have always had a mathematical view of what is going on, which throughout this thread has got sharper - there is nothing like continual argument to encourage better understanding. The words I use here are just different attempts to make this understanding clear to others.

I think that you have been tying yourself in knots. Is it too difficult to understand that when D=v*t and Dp=v*tp, and that D=Dp one must have that t=tp?

If you check the frames in which these measurements are made you will see that both D and t depend on frame. Thus if the distance to alpha centauri is 4 light-years in earth frame, in the frame of the twin travelling with gammas = 2 to alpha centauri, the distance to travel is only 2 light-years.

[tomclarke]

so I knew Johan was wrong because his claims were contrary to experiment

Which experiment?

http://en.wikipedia.org/wiki/Time_dilat ... nfirmation

and some of the things he was saying did not make sense,

Like what? Does it make more sense to say that two twins who experience the same time rate will age at different rates? Are you really serious?

That is not what I have said. One twin has more time to age than the other between the two events when they meet.The rate of aging is the same (inasfar as this has any meaning - rate relative to what?).

Your statements do not make sense when you talk about "clocks keeping time at the same rate" without specifying the frames in which these rates are measured. Also when you talk about "the same instant in time" without specifying in which frame time is being measured. Finally when you say the GPS satellite clock SR rate change is only apparent in the earth frame it does not make sense.