Room-temperature superconductivity?

Point out news stories, on the net or in mainstream media, related to polywell fusion.

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tomclarke
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Post by tomclarke »

Happy wrote: yeah, it just frustrates me. i give up. i recall in reading "surely you're joking, mr. feymann" feymann's remarks that he found even doctoral physicists failed to grasp basic concepts to the extent of not being able to answer questions that should be trivially easy. though clearly upsetting, perhaps it is we who are in error when we find this also surprising.
Wow.

Give me a list of these questions. I'm not even a physicist, just enjoying learning SR on this thread, but I have not found any questions recently I could not answer. And answer consistently. You know, being able to answer all questions does not necessarily mean correctness.

happyjack27
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Post by happyjack27 »

tomclarke wrote:
Happy wrote: yeah, it just frustrates me. i give up. i recall in reading "surely you're joking, mr. feymann" feymann's remarks that he found even doctoral physicists failed to grasp basic concepts to the extent of not being able to answer questions that should be trivially easy. though clearly upsetting, perhaps it is we who are in error when we find this also surprising.
Wow.

Give me a list of these questions. I'm not even a physicist, just enjoying learning SR on this thread, but I have not found any questions recently I could not answer. And answer consistently. You know, being able to answer all questions does not necessarily mean correctness.
oh well i only recall reading 2 questions in feymann's book. (i certainly hope he didn't base his conclusion on such a small sample size!) one was to students at a college regarding polarized light. something like:

"the sun is setting and low on the horizon, and bounces of the water and into our second story window. describe the polarization of the light from the sun that hits the window."

this one should take seconds to answer for anyone who had spent an entire semester learning about the polarization of light (like the class had), nonetheless a single day.

so that was to students who had just taken a class. it was an exam question that nearly every student got wrong. the other one he posed to, i believe, a tenured astrophysicsts, or something like that. and if i recall correctly it was about GR, and how far should a rocket go up before dropping back down to earth to maximize its net time dilation experienced by the time it hits the ground. this one, as the saying goes, you don't need to be a rocket scientist to answer, but this guy quite literally WAS a rocket scientist, and he was STUMPED!

anyways, it was a good book, amusing and insightful. i recommend it.

EDIT: oh no, the second question was more complicated i recall now. you had to also compensate for the fact that a faster rocket would also be affected by SR. but, i mean, really, the answer is obvious: geosynchronous orbit.

tomclarke
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Post by tomclarke »

happyjack27 wrote:
tomclarke wrote:
Happy wrote: yeah, it just frustrates me. i give up. i recall in reading "surely you're joking, mr. feymann" feymann's remarks that he found even doctoral physicists failed to grasp basic concepts to the extent of not being able to answer questions that should be trivially easy. though clearly upsetting, perhaps it is we who are in error when we find this also surprising.
Wow.

Give me a list of these questions. I'm not even a physicist, just enjoying learning SR on this thread, but I have not found any questions recently I could not answer. And answer consistently. You know, being able to answer all questions does not necessarily mean correctness.
oh well i only recall reading 2 questions in feymann's book. (i certainly hope he didn't base his conclusion on such a small sample size!) one was to students at a college regarding polarized light. something like:

"the sun is setting and low on the horizon, and bounces of the water and into our second story window. describe the polarization of the light from the sun that hits the window."

this one should take seconds to answer for anyone who had spent an entire semester learning about the polarization of light (like the class had), nonetheless a single day.

so that was to students who had just taken a class. it was an exam question that nearly every student got wrong. the other one he posed to, i believe, a tenured astrophysicsts, or something like that. and if i recall correctly it was about GR, and how far should a rocket go up before dropping back down to earth to maximize its net time dilation experienced by the time it hits the ground. this one, as the saying goes, you don't need to be a rocket scientist to answer, but this guy quite literally WAS a rocket scientist, and he was STUMPED!

anyways, it was a good book, amusing and insightful. i recommend it.

EDIT: oh no, the second question was more complicated i recall now. you had to also compensate for the fact that a faster rocket would also be affected by SR. but, i mean, really, the answer is obvious: geosynchronous orbit.
Students don't make connections when learning stuff: they are just not good at it till third year uni (and some don't learn even by then). But good ones do.

kcdodd
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Post by kcdodd »

Yes I know I have "ah ha" moments about undergrad stuff all the time.
Carter

johanfprins
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Post by johanfprins »

tomclarke wrote: I'm not even a physicist, just enjoying learning SR on this thread, but I have not found any questions recently I could not answer And answer consistently.
Yes you gave answers but they are all wrong. I had a student who always had an answer but it was never really an answer. You remind me of him. I think that you do not understand what consistency means: This in addition to the fact that you refuse to do the simple algebra I have posted on Wednesday; or maybe you just are not competent enough to follow simple mathematical logic?
[You know, being able to answer all questions does not necessarily mean correctness.
Exactly and you have been CONSISTENTLY WRONG on this thread.

So let me try again: Twin1 in K and twin2 in Kp; They synchronise their clocks at the beginning of the journey and then move away from one another with a RELATIVE SPEED v. Both have atomic clocks, and the transitions on which these clocks are based MUST according to Einstein's first postulate be the same in both reference frames. Thus within both reference frames the clocks MUST keep the same time with respect to each reference frame within which each clock is stationary. This means that after a time T(E) on the clock of twin1 there is a time Tp(E) on the clock of twin2 and that T(E)-Tp(E). This also means that at that instant in time twin2 is a distance D=v*T(E) from twin 1 and similarly twin1 is a distance D=-v*Tp(E) away from twin2. The actual distance between them, as measured from either twin, is thus the same; namely D.

As already pointed out on Wednesday, if twin 1 now sends out a light pulse at the time T(E)=Tp(E) then, although this light pulse moves with speed c relative to twin1, it must also move with speed c relative to twin2. Thus to find out what twin2 sees within his inertial reference frame one must transform the coordinates X=0, and T=T(E) of this appearance of the light pulse within K, into Kp. The coordinates within Kp are thus Xp(Ep) and Tp(Ep) given by the Lorentz transformation as:

Xp(Ep)= -(gamma)*v*T(E)=-(gamma)*D....................................[1]

Thus the distance relative to twin1 at which the light pulse appears IS LARGER than the ACTUAL DISTANCE D between twin1 and twin2. This is counterintuitive but is what the Lorentz transformation gives: And when you ignore this increase in distance, you reach the wrong conclusions that tomclarke has posted repeatedly, and with false confidence, on this thread.

Furthermore

Tp(Ep)=(gamma)*T(E)..........................................[2]

In addition to the fact that the light pulse appears at a longer distance away from twin2 than the ACTUAL DISTANCE D between the twins, twin2 also sees it appearing at a later time Tp(Ep) than the actual time T(E) that twin1 sends the pulse. If you do not take BOTH these dilations into account you draw the silly, and wrong, time-space diagrams that tomclake has posted.

Now as I have also have posted it is simple to derive at which time Tp(A) on twin2’s clock that the light pulse will reach twin2. Since I have already shown how the derivation must be done I will just post the result: is longer than the actual

Tp(A)=(1+v/c)*(gamma)*T(E)...............................[4]

But twin2 also sends out a light pulse at time Tp(E)=T(E) when the two twins are an ACTUAL DISTANCE D apart twin 1.
According to the Lorentz transformation this light pulse appears within the reference frame of twin1 at position X(Ep) and at a time T(Ep) where:

X(Ep)=(gamma)*v*Tp(E)...............................................[8]
and
T(Ep)=(gamma)*Tp(E)..................................................[9]

And as already derive the time T(A) on the clock of twin1 that this light pulse reaches twin1 is:

T(A)=T(Ep)+X(Ep)/c= (1+v/c)*(gamma)*Tp(E)..................[10]

Since T(E)=Tp(E) then according to Eqs. [4] and [10] one must have that T(A)=Tp(A) Thus both twins receive the other twin’s light pulse when their clocks show the exact same time on their respective cocks.

Now let us slightly change the argument at this point, and assume that the twins agreed that after each has received the first light pulse they will both send out their second light pulse at the instant when the receive each others incoming light pulse. So they send out their second light pulses at T(E)2=T(A) and Tp(E)2=Tp(A): Thus in this case T(E)2=Tp(E)2, and if you go through the mathematics again the twins will now simultaneously receive the second light pulses at time T(A)2 and Tp(A)2, where:

T(A)2=(1+v/c)*(gamma)*Tp(E)2=(1+v/c)*(gamma)*Tp(A)

And from Eq. [4] this becomes:

T(A)2=(1+v/c)*(gamma)*[(1+v/c)*(gamma)*T(E)]=
{[(1+v/c)*(gamma)]^2}*T(E)……………...................................[11]

Similarly for

Tp(A)2={[(1=v/c)*(gamma)]^2}*T(E)………………………….(12)

And again T(A)2=Tp(A)2

Thus after N pulses twin1 receives the Nth pulse at time T(A)N on his clock where:

T(A)N={[(1+v/c)*(gamma)]^N}*T(E)…………………………..(13)

And

Tp(A)N={[(1+v/c)*(gamma)]^N}*T(E)………………………….(14)

And of course again we have that T(A)N=Tp(A)N. The times on the clocks are still exactly the same when the two twins receive the Nth light pulse simultaneously.

To simplify the mathematics, we can assume without any loss in generality, that at the instant that each receive the Nth pulse simultaneously, they start to move back towards on another, and at the same instant each one sends out the (N+1)th pulse at the time T(A)N=Tp(A)N. Since they are now moving towards each other the Doppler factor changes from (1+v/c) to (1-v/c) so that the signals reach the twins at times so that the pulse from twin1 will reach twin2 at a time Tp(A)(N+1) which similar to Eq. [4] is now given by:

Tp(A)(N+1)=(1-v/c)*(gamma)*Tp(A)N…………………………(15)

And the pulse from twin2 reaches twin1 at the time T(A)(N+1) which similar to Eq. [10] is given by:

T(A)(N+1)=(1-v/c)*(gamma)*T(A)N……………………………(16)

Thus since Tp(A)N=T(A)N, the twin’s clocks still read the same when they each receive the (N+1)th pulse from the other twin.

After M pulses during the return journey the times on the clocks when the twins receive and send out pulses are Tp(A)(N+M) and T(A)(N+M)

Where Tp(A)(N+M)={[(1-c/v)*(gamma)]^M}*Tp(A)N……….(17)

And

T(A)(N+M)={[(1-c/v)*(gamma)]^M}*T(A)(N)…………………(18)

An since Tp(A)N=T(A)N one must have that T(A)(N+M)=Tp(N+M). Thus if the two twins reach one another after each one of them has received M pulses on the return journey, their clocks will read exactly the same time. Although, owing to the Doppler effect, the number of pulses N on the outward leg is not the same as the the number of pulses M on the return leg the total number of pulses received by each twin is during the whole journey is exactly the same namely (N+M): And since the clocks of the twins read exactly the same time when each receives the others pulse, their clocks will also show exactly the same time after the whole journey is completed.

I think the derivation is now so clear that even my goldfish will understand it. I hope that tomclarke will now do the honourable thing and admit that he was wrong all the time and apologise to all of us for having wasted so much of our time on this thread.

tomclarke
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Post by tomclarke »

tomclarke wrote:
johanfprins wrote:
tomclarke wrote: That is symmetric, but when one twin turns around it affects his counting of other twin's time immediately,
No it affects the counting of the incoming signals for BOTH twins immediately and the effect is the SAME in both reference frames.
There is no need for further communication between us Johan. I agree entirely that if this is true you are right and I wrong.

Go back to my pictures.

What you propose would be a clear violation of causality, because only the twin that turns around knows when the turnaround will happen.

I'll let you think about that, but will not answer your further posts until you have changed this statement, since there would be no point in furher debate.

johanfprins
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Post by johanfprins »

tomclarke wrote:
johanfprins wrote:
tomclarke wrote: That is symmetric, but when one twin turns around it affects his counting of other twin's time immediately,
No it affects the counting of the incoming signals for BOTH twins immediately and the effect is the SAME in both reference frames.
There is no need for further communication between us Johan. I agree entirely that if this is true you are right and I wrong.
What I have stated is a fact and I havae also derived this fact meticulously from the Lorentz transformation. A pity that you cannot even do or follow high school algebra.
Go back to my pictures.
Why should I go back to rubbish?
What you propose would be a clear violation of causality, because only the twin that turns around knows when the turnaround will happen.
Causality? You do not even know what this word means!
I'll let you think about that, but will not answer your further posts until you have changed this statement,
Why must I recant the truth? Do you think you are the Pope and I am Galileo so that you can force me to admit that I am wrong while I am not?
Since there would be no point in furher debate.
I agree it has been a waste of time to argue with a klutz like you. Good riddance!

happyjack27
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Post by happyjack27 »

tomclarke wrote: Students don't make connections when learning stuff: they are just not good at it till third year uni (and some don't learn even by then). But good ones do.
oh my god i certainly hope that is not true, that sounds just awful! developmentally speaking a person's brain develops that ability in their early teens. by then their brain is fully capable of doing that kind of thinking and as ready as it will ever be. to think that it lies dormant for another ten years in an entire population out of mere choice is just unfathomable!

if what you say is true then there is something SERIOUSLY wrong with our education system and/or culture.

happyjack27
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Post by happyjack27 »

not to mention that they're not actually LEARNING ANYTHING if they can't do this. so you're saying we don't actually start LEARN ANYTHING until we're juniors in college!

ScottL
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Post by ScottL »

Trying to understand further:
SR does not declare that all frames of reference are equivalent, only so-called inertial frames
The accelerating twin is not inertial while they're accelerating which is observationally detectable. The acceleration was experienced by one twin and obviously not by the other.

Correct?

GIThruster
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Post by GIThruster »

That's true, Scott; but the twins paradox is not based upon acceleration asymmetries, it's based upon velocity alone. You'll find this in Uncle Al's own words in the paper cited by me back in the thread.

The thing to keep in mind here, is that Johan simply says over and over "I proved it" until everyone gives up. Tom lasted many more pages than most would. Doesn't change the fact that everyone in the world who knows this stuff, knows Einstein is right and Johan is wrong and unless you're a physicist who is used to correcting the papers of SR students, it's not worth even looking at Johan's bad joke.

Note, he ran away from the physics forum people and decided to camp here, where there are no real experts. That in itself ought to tell you something.
"Courage is not just a virtue, but the form of every virtue at the testing point." C. S. Lewis

johanfprins
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Post by johanfprins »

ScottL wrote:Trying to understand further:
SR does not declare that all frames of reference are equivalent, only so-called inertial frames
The accelerating twin is not inertial while they're accelerating which is observationally detectable. The acceleration was experienced by one twin and obviously not by the other.

Correct?
That is how an inertial refrence frame was initially defined by Galileo and Newton. Einstein later, when he developed his so-called "General Theory of Relativity" also pointed out that an accelerating inertial refrence frame in free fall is also an inertial reference frame in the same sense as Galileo and Newton described non-accelerating inertial reference frames.

But in special relativity the Lorentz transformation has not been derived for acceleration. The twins paradox in Special Relativity does not include any acceleration or deceleration. This is also not included in tomclarke's diagrams. In Special Relativity you only have constant motion at a relative speed of v between the twins and a sudden change in this relative speed from v (outbound) to -v (inbound). Since the speed stays relative when the speeds switch, it is stupid to maintain that one or the other twin is" turning back". I did the whole analysis above by using the Lorentz transformation for outbound and inbound motions and proved impeccacbly that the clocks with the two twins must keep the same time all the way.

If you want to argue that there will be a difference when the turnaraound occurs by one twin decelerating from v to reach speed -v, my analysis still proves that if this is so this change in time can only be solely ascribed to the deceleration, and NOT to thbe Lorentz transformation at all; as tomclarke has been arguing on the thread.

But I even doubt that this is correct since you can havein principle free fall deceleration that causes the turnaround to be considere by both twins as happening to the other twin whioc is decelerating from a relative speed of v to a relative speed of -v.

I also suspect, that this must also be so if the twin that decelerates experience the decelerating force within his spacecraft. But as Einstein also pointed out, this twin will conclude that he is in a gavity field.

I suspect that it will be found that Einstein was not correct by concluding that the latter force, which acts like gravity, will slow down a clock as a gravity field acrually does. But the latter is further research for the future.

It is, however, safe to claim that the Lorentz transformation dealing with constant speeds v outbound and -v inbound, DOES NOT mandate that the twins must age at different rates. In fact, if they doage at different rates, it will be a violation of Einstein's first postulate.

ladajo
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Post by ladajo »

Johan,
Can I simply that to say that you mean that Dilation occurs only in the presence of Acell, Decell, or Gravity? And that your entire point is that during the phase of travel at constant speed, there is no rate difference?

If this is correct, then could we run an experiment with a centrifuge where we measure the rate of change in the clock rate during spin up, at speed, and spin down? Although my initial take thinks that angular momentum would apply.
In thinking about the orbiting satellites, that would mean also that incurred SR is merely a component of the angular momentum.
So what we really need is a comparison of a non-orbit clock, like the one on a transiting space craft not in orbit, nor in a course correction cycle?

tomclarke
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Post by tomclarke »

GIThruster wrote:That's true, Scott; but the twins paradox is not based upon acceleration asymmetries, it's based upon velocity alone. You'll find this in Uncle Al's own words in the paper cited by me back in the thread.

The thing to keep in mind here, is that Johan simply says over and over "I proved it" until everyone gives up. Tom lasted many more pages than most would. Doesn't change the fact that everyone in the world who knows this stuff, knows Einstein is right and Johan is wrong and unless you're a physicist who is used to correcting the papers of SR students, it's not worth even looking at Johan's bad joke.

Note, he ran away from the physics forum people and decided to camp here, where there are no real experts. That in itself ought to tell you something.
I gave up because Johan posted very clearly something that is in violation the laws of nature. Anyone can refer back to his post to see why, and I think most will understand that information cannot travel faster than the speed of light, so there is no way the startionary twin's reception of light pulses could change frequency at the same time (in any frame) as the moving twin changes direction. The change in frequency is only received after the light pulses from the post-turnaround twin get to the stationary twin. Of course if both frequencies changed at the same time Johan would be right, because there is would then be no asymmetry.

As you say, the problem is about change in velocity, not acceleration, and my post shows precisely why it is asymmetric, without using any physics except Doppler effect. A school-child could understand it, so the fact that Johan does not means that there is no point continuing the conversation.

If anyone wants to correct Johan's ramblings he makes a number of key mistakes as well as the egregious one I can't forgive:

He thinks (in a confused way) that SR time dilation is "not real". This is quite a subtle matter however, so many are confused.

He incorrectly dismisses all the contrary experimental evidence

He sees the definition of proper time (that clocks in rest frame all run at the rate physics says) as a proof that "all clocks run at the same rate".

This is a triumph of words over physics. As teahive and others here have pointed out, for "clocks run at the same rate" to have meaning we must compare rates. To compare rates you need to compare clocks twice. One comparison can be done between moving frames no trouble, because the clocks can be colocated. for the second comparison you need to compare separated clocks which breaks downm in a relativistic world. this comparison is frame-dpendent. Therefore "keeping time" is frame dependent.

Einstein's postulate, that Johan quotes over and over again, says that in a local frame clocks obey the same local physical laws. it says nothing about the relationship between frames, or whether or not two clocks "keep the same time". I have asked Johan to construct a physical thought experiment which would explain his concept of "keeping time". He has always failed.

Johan's mode of argument should alert anyone. We all like to give our own solutions, which we think are good, but Johan is unique in being logically unable to criticise an opponent's argument. When he encounters a logical step with a conclusion he dislikes he says "that is not true because I know the contrary" and repeats his own different reasoning. He very rarely shows why the argument that lead to that conclusion is faulty. That, of course, is usually because the argument he criticises is in fact correct, but I am not sure he has the mental capacity to do this: certainly he does not use it here.

I have enjoyed my time on this thread thinking about and (re) learning SR as I went. The ideas are stimulating, and finding a clear way to think about them equally so. I have Johan to thank for making me sharpen my understanding and see exactly what is asymmetric in the twins paradox. Something that the "Doppler effect" argument does, and till I thought of it I did not deeply understand.

Best wishes, Tom

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Post by tomclarke »

ladajo wrote:Johan,
Can I simply that to say that you mean that Dilation occurs only in the presence of Acell, Decell, or Gravity? And that your entire point is that during the phase of travel at constant speed, there is no rate difference?

If this is correct, then could we run an experiment with a centrifuge where we measure the rate of change in the clock rate during spin up, at speed, and spin down? Although my initial take thinks that angular momentum would apply.
In thinking about the orbiting satellites, that would mean also that incurred SR is merely a component of the angular momentum.
So what we really need is a comparison of a non-orbit clock, like the one on a transiting space craft not in orbit, nor in a course correction cycle?
You could compare experiments which show SR effects at different radii - and hence different ratios of acceleration to velocity. Like.... satellites?

To my knowledge all results are consistent with time dilation being a velocity effect, and must therefore be inconsistent with its being an acceleration effect. Note that any periodic object undergoes continuous (oscillatory) acceleration so you are right it is necessary to be careful to see whetehr the dliation observed is correlated with velocity or acceleration.

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