Room-temperature superconductivity?

[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.

[tomclarke]

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!

Here is an example of things you say which do not make sense. Even in Newtonian spacetime the two twins clearly travel on different paths through spacetime.

It is peculiar to relativistic spacetime, I agree, that the proper time along the two paths is different. But your assertions that proper time along any two such paths must be the same does not prove this is the case.

[johanfprins]

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.

You are wrong. Do the calculation.

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

So? It affects the time difference between a pulse being sent and an incoming pulse being recorded. It does not affect the fact that both twins have sent out the same number of pulses during the whole outwards and inwards journey. So you are wrong again.

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.

Wrong again. Do the full calculation. On the outwards journey the two light sources move away from one another and the light will be red-shifted but this does not affect the number of pulses. Similarly on the return journey the light will be blue shifted, but this will also not affect the number of pulses sent out by each twin. Do you know what the Doppler effect is?

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

YOU are the one that is not careful and who do not even understand that the Doppler shift does not change the number of pulses being sent out but only the time intetval between the pulse where they are recorded.

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!).

So if it is technically not even a metric! Why do you insist that it describes an actual 4D space-time coordinate transition? Can you not see how you are flip-flopping? Romney is probably in need of your able help.

Again can you do the mathematics v*t=v*tp? Do you know how to divide by v on both sides?

[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?

If you check the frames in which these measurements are made you will see that both D and t depend on frame.

No they do not! two bodies in space can only hvae a single distance between them unless space is curved which it is not when there is no gravity.

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.

Wrong again. The twin's clock keep the same time as my clock on earth (neglecting gravity) and the distance he will travel to reach alpha centauri will be the same distance; unless you believe in Voodoo as you obviously do!

[johanfprins]

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

Which experiment?

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

Why are you dishonest? I am NOt talking about experiments measuring time dilation of a moving clock within a refrence frame relative to which it is moving. We are in full agrreement on that. What I talk about is comparing two clocks after one has travelled without experiencing any change in gravity. I did not see such an experiment in your wiki reference.

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?

T

hat is not what I have said. One twin has more time to age than the other between the two events when they meet

This is impossible if their clocks are keeping the same time as you admit that they must do.

.The rate of aging is the same (inasfar as this has any meaning - rate relative to what?).

rate as measured by their clocks which MUST according to Einstein's firts postulate keep the exact same time rate, and since they have been synchronised at the beginning of the journey, must also show the same elapsed time atn the end of the journey.

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.

I did specify the refrence frames all along: I stated time and again that all stationary clocks MUST keep the same time rate within the inertial reference frame each one is stationary within. Why do you have to be dioshonest?

Also when you talk about "the same instant in time" without specifying in which frame time is being measured.

It shouod be obvious to anybody that if I and friend have the same perfect clocks and we synchronise them and then go our seperate ways, then when I look at my clock at any instant of time later on thye time on m,y friend's clock will be exactly the same "whether he is within the same refrence frame as I am or not". This is just plain logic which even my grandson of 4 can easily understand.

Finally when you say the GPS satellite clock SR rate change is only apparent in the earth frame it does not make sense.

If I explain it to you then it is my "English" When I do it mathematically you ignore it. So let us again write down the time dil;ation formula: (delta)t=(gamma)*(delta)ts where (delta)ts is the time interval ON THE CLOCK ON THE SATTELITE! Is (delta)ts the dilated time? NO! Is (delta)t the time on another perfect clock on erath (ignoring gravity?? AGAIN NO! So which clock is ACTUALLY dilated? NOT the clock on erath NOR the clock on the sattelite. Only when we communicate with EM waves between the clocks must this apparent time dilation be taken into account. It is not a reall diffrence in time between clocks and therefore there is NOT a REAL space-time PATH involved!

I have to rush to a meeting!

[tomclarke]

Wrong again. Do the full calculation. On the outwards journey the two light sources move away from one another and the light will be red-shifted but this does not affect the number of pulses. Similarly on the return journey the light will be blue shifted, but this will also not affect the number of pulses sent out by each twin. Do you know what the Doppler effect is?

A moment's thought will tell you that if doppler shift affects frequency it must also affect period of a sequence of pulses.

Or, don't think, if that is difficult, see what UG MIT courses say about pulsar astronony:

http://www.youtube.com/watch?v=5wM-5gPHDM4

Topics covered: Doppler Effect, Binary Stars, Neutron Stars and Black Holes. Doppler shift is introduced with sound waves, then extended to electromagnetic waves (radiation). The Doppler shift of stellar spectral lines and/or pulsar frequencies provides a measure of the line-of-sight (so-called radial) velocity of the source relative to the observer. Combined with Newton's law of universal gravitation, this can lead to the orbital parameters and the mass of both stars in a binary star system.

[tomclarke]

So let us again write down the time dil;ation formula: (delta)t=(gamma)*(delta)ts where (delta)ts is the time interval ON THE CLOCK ON THE SATTELITE! Is (delta)ts the dilated time? NO! Is (delta)t the time on another perfect clock on erath (ignoring gravity?? AGAIN NO! So which clock is ACTUALLY dilated? NOT the clock on erath NOR the clock on the sattelite. Only when we communicate with EM waves between the clocks must this apparent time dilation be taken into account. It is not a reall diffrence in time between clocks and therefore there is NOT a REAL space-time PATH involved!

It is true that time dilation is difficult to measure directly between two frames with uniform velocity. However even in this case it is the (real) difference in time on the moving clock for a given fixed clock time in the stationary frame.

Thus. Set up clocks throughout space in the stationary frame to be synchronised. (True, you use e-m rays to do this). Using these clocks, which whizz by, you can compare the moving clock with the stationary frame time.

Time dilation says that when 1s has elapsed on the moving clock the whizzing by stationary clocks will register more than 1s elapsed.

The time dilation is easily seen without extra clocks by making the moving clock return and comparing times, as in the twins paradox.

Best wishes, Tom

[tomclarke]

It shouod be obvious to anybody that if I and friend have the same perfect clocks and we synchronise them and then go our seperate ways, then when I look at my clock at any instant of time later on thye time on m,y friend's clock will be exactly the same "whether he is within the same refrence frame as I am or not". This is just plain logic which even my grandson of 4 can easily understand.

Perhaps your grandson aged 4 does not yet understand relativistic physics?

And you are here making the mistake I highlighted above - assuming some frame-independent measure of instantaneity for events spatially separated.

best wishes, Tom

[johanfprins]

Wrong again. Do the full calculation. On the outwards journey the two light sources move away from one another and the light will be red-shifted but this does not affect the number of pulses. Similarly on the return journey the light will be blue shifted, but this will also not affect the number of pulses sent out by each twin. Do you know what the Doppler effect is?

A moment's thought will tell you that if doppler shift affects frequency it must also affect period of a sequence of pulses.

Oh my Oh my!! During a Doppler shift the frequency of the light source DOES NOT change ONLY the frequency with when you detect the light. And both twins experience THE SAME Doppler shift (red) when they move away from one another and THE SAME Doppler shift (blue) when they again approachh one another. So how the HELL can the Doppler shift change the period of regular pulses coming from their light sources?

This period stays exactly the same and when you apply the Lorentz transformation correctly as I have asked you to do, and which you obviously cannot do, you will find when the two twins both send out a light pulse every second, they will each have sent out THE SAME NUMBER OF LIGHT PULSES when they again meet up. When you do the calculation, if you can, you will see that the Lorentz transformation directly proves that the Doppler shift DOES NOT change this fact.

Or, don't think, if that is difficult, see what UG MIT courses say about pulsar astronony:

http://www.youtube.com/watch?v=5wM-5gPHDM4

Topics covered: Doppler Effect, Binary Stars, Neutron Stars and Black Holes. Doppler shift is introduced with sound waves, then extended to electromagnetic waves (radiation). The Doppler shift of stellar spectral lines and/or pulsar frequencies provides a measure of the line-of-sight (so-called radial) velocity of the source relative to the observer. Combined with Newton's law of universal gravitation, this can lead to the orbital parameters and the mass of both stars in a binary star system.

What are you trying to say in your usual foggy manner? This has NOTHING to do with the argument we are having. Have you REALLY studied physics, where, and who were your mentors?

The fact is that when two perfect clocks keep exactly teh same time within two inertial refrence frames, as demanded by Einstein's first postulate, and as accepted by you that it must happen, THEN, when the one clock shows within its inertial reference frame that a time-interval (delta)t has passed, the other clock must show also show within its inertial reference frame that the SAME time interval (delta)t has passed. Anything other conclusion is paranormal, metaphysical Voodoo!

[ScottL]

http://en.wikipedia.org/wiki/Hafele%E2% ... experiment

It appears the experiment was done and not just done, but repeated with a precision within 1%.

Experiments conducted: 1971, 1976, 1996, and more with increasing precision.

[Teahive]

Johan,

you continue to talk about a "time rate". As you are surely aware, a "rate" is a quotient of two quantities. Could you explain which two quantities you mean?

Wrong again. Do the full calculation. On the outwards journey the two light sources move away from one another and the light will be red-shifted but this does not affect the number of pulses. Similarly on the return journey the light will be blue shifted, but this will also not affect the number of pulses sent out by each twin. Do you know what the Doppler effect is?

I did the calculation. The result is that the observers disagree on the amount of time which elapsed during the journey, which is consistent with the travelling person experiencing a shortening of the distance during travel.