Room-temperature superconductivity?

[johanfprins]

Even Einstein missed this fact since he explained non-simultaneity by assuming that an observer can "rush into a light beam" (this moving wioth speed c+v relative to the light beam) and "rush away from a l;ight beam (thus moving with a speed (c-v) relative to the light beam). By directly using the Lorentz transformation it is easy to prove that the light beam coming from the front is still approaching the moving observer with speed c and the light beam from the back also still approaches the observer with a speed c. Although non-simultaneity occurs, Einstein's explanation of it is wrong.

This is incorrect. Einstein's explanation does not require the light to move faster relative to an observer. For a "stationary" observer the distances travelled in each direction are different, though.

Let me quote Einstein from his book: "Relativity: The special and general theory" page 26: He is now talking about the observer on the train: "Now in reality (considered with reference to the railway embankment) he is hastening towards the light beam coming from B, whilst he is riding on ahead of the beam coming from A. etc."

This clearly must mean that Einstein argued that during the motion of the observer towards B, the relative speed between him and the light is c+v, which is larger than c, and the relative speed between him and the light coming from A is c-v, which is smaller than the speed of light. According to Einstein's second postulate the speed of light relative to ANY moving object is always, and can only be c.

And, in fact, when you model this train experiment by doing Lorentz coordinate transformations, you will find that the relative speed between the light beams and the moving observer, as measured relative to the embankment, remain c for both the light from the front and the back of the train. No observer can thus "hasten into a light beam coming towards him" or "ride ahead" of a light beam coming from behind him; no matter within which inertial reference frame his speed v and the light speed c are simultaneously being measured. I was also gobsmacked when I discovered this.

This behaviour also proves that there is not any actual length contraction of a rod passing by. I have posted a draft copy of a manuscript, in which I do the derivations directly from the Lorentz transformation, on my website www.cathodixx.com as a pdf file "Einstein".

[Teahive]

Let me quote Einstein from his book: "Relativity: The special and general theory" page 26: He is now talking about the observer on the train: "Now in reality (considered with reference to the railway embankment) he is hastening towards the light beam coming from B, whilst he is riding on ahead of the beam coming from A. etc."

The important part here is "considered with reference to the railway embankment".

You may not understand German, but you might understand the picture accompanying this explanation:
http://de.wikibooks.org/wiki/A._Einstei ... l:_%C2%A72

Relative to the embankment, the path the light has to travel is longer in the direction of movement of the rod, and shorter in the opposite direction. Relative to the moving rod it's the same in both directions. That is precisely why the two reference frames must have a different notion of simultaneity, and therefore time.

This clearly must mean that Einstein argued that during the motion of the observer towards B, the relative speed between him and the light is c+v, which is larger than c, and the relative speed between him and the light coming from A is c-v, which is smaller than the speed of light. According to Einstein's second postulate the speed of light relative to ANY moving object is always, and can only be c.

But you are not looking at the speed of light relative to a moving object. You're looking at the speed of light relative to the embankment which is at rest in the chosen reference frame.

[johanfprins]

The important part here is "considered with reference to the railway embankment".
You may not understand German, but you might understand the picture accompanying this explanation:
http://de.wikibooks.org/wiki/A._Einstei ... l:_%C2%A72

Oh I know the picture as well as the correct rider "considered with reference to the railway embankment". My dear Teahive I have taught Special Relativity for many years and have also made the same mistake you are making here UNTIL, to my astonishment, I found that this explanation violates the Lorentz transformation: And any explanation which gives a different picture than you obain by using the Lorentz transformation directly, must be wrong.

Oh and by the way: I understand German very well indeed. Not using it every day anymore, as I have had when I were young, I am not as fluent anymore: But I can assure you that I understand it.

Relative to the embankment, the path the light has to travel is longer in the direction of movement of the rod, and shorter in the opposite direction. Relative to the moving rod it's the same in both directions.

Why do you not do the actual Lorentz coordinate transformations instead of thinking in Galilean terms? Only according to the Galilean transformation is it true what you have just claimed. According to the Lorentz tranformation both the lengths and time intervals adjust in both directions so that the speed of light approaching the observer on the train from the front and from the back, approaches him, as measured relative to himself, with the exact same speed c, as is also measured relative to the embankment. Just do the mathematics instead of using "logic" based solely on the Galilean transformation: The latter does not apply at high speeds.

JFP: This clearly must mean that Einstein argued that during the motion of the observer towards B, the relative speed between him and the light is c+v, which is larger than c, and the relative speed between him and the light coming from A is c-v, which is smaller than the speed of light. According to Einstein's second postulate the speed of light relative to ANY moving object is always, and can only be c.

Teahive: But you are not looking at the speed of light relative to a moving object. You're looking at the speed of light relative to the embankment which is at rest in the chosen reference frame.

You are looking at the speed of light relative to the embankment as well as relative to the moving observer. According to the Lorentz transformation this relative speed is c and cannot be anything else but c in both cases. Do the mathematics and stop thinking in terms of the Galilean transformation: As I have pointed out the latter does NOT apply at high speeds.

[Teahive]

Why do you not do the actual Lorentz coordinate transformations instead of thinking in Galilean terms? Only according to the Galilean transformation is it true what you have just claimed. According to the Lorentz tranformation both the lengths and time intervals adjust in both directions so that the speed of light approaching the observer on the train from the front and from the back, approaches him, as measured relative to himself, with the exact same speed c, as is also measured relative to the embankment. Just do the mathematics instead of using "logic" based solely on the Galilean transformation: The latter does not apply at high speeds.

Johan, a while ago I thought I had found the same astonishing mistake in Einstein's explanation as you did. But I've realised it was me who made a mistake, not Einstein and the countless other physicists using SR. I am not arguing that any observer will measure anything other than c as the speed of light.

Relativistic addition of velocities gives you the relative velocity between two moving objects as observed from each of them, not as observed in a third FOR. Two spaceships leaving Earth in opposite directions, at v=2/3 c, will both reach stars four lightyears away in 6 years, as observed from earth (taking into account the signal delay of 4 years). Thus an observer on Earth sees the distance between the spaceships growing at 4/3 c. Relative velocity of two objects, as observed in a third FOR, can therefore exceed c. However, each spaceship will observe Earth moving away at 2/3 c and the other spaceship moving away at 0.92c.


Ok, let's do the Lorentz transformation:
Assume a rod with a pulsed lamp, light sensor, and clock at one end (A), and a mirror at the other end (B).
Within the rod's stationary frame of reference K, with proper time t and position along the rod x:
- The distance AB measures 1 lightsecond. Let A be at x=0, B at x=1.
- There are three relevant events
-- E0: Send out light pulse from A: t = 0, x = 0
-- E1: Reflect light pulse at B: t = 1, x = 1
-- E2: Receive reflected light pulse at A: t = 2, x = 0

Now let's assume an observer which moves at 2/3 c relative to the rod along the AB direction, γ ≈ 4/3
Within the observer's frame of reference K', with proper time t' and position along the rod x':
- We define E0 as the origin, t' = 0, x' = 0
- E1: t' = γ (t - xv/c²) = 4/9 , x' = γ (x - tv) = 4/9
- E2: t' = γ (t - xv/c²) = 24/9 , x' = γ (x - tv) = -16/9

The observer measures light travel at c in his own reference frame. He sees the light travel 4/9 seconds from A to B, then 20/9 seconds back from B to A.
And to show length contraction: (t=2/3, x=1) transforms to (t'=0, x'=0.75). So the observer (or two observers stationary in K', communicating with each other) will find that, at time t' = 0, the ends of the rod are 0.75 lightseconds apart in K'.

[krenshala]

Why do you not do the actual Lorentz coordinate transformations instead of thinking in Galilean terms? Only according to the Galilean transformation is it true what you have just claimed. According to the Lorentz tranformation both the lengths and time intervals adjust in both directions so that the speed of light approaching the observer on the train from the front and from the back, approaches him, as measured relative to himself, with the exact same speed c, as is also measured relative to the embankment. Just do the mathematics instead of using "logic" based solely on the Galilean transformation: The latter does not apply at high speeds.

Johan, a while ago I thought I had found the same astonishing mistake in Einstein's explanation as you did. But I've realised it was me who made a mistake, not Einstein and the countless other physicists using SR. I am not arguing that any observer will measure anything other than c as the speed of light.

Relativistic addition of velocities gives you the relative velocity between two moving objects as observed from each of them, not as observed in a third FOR. Two spaceships leaving Earth in opposite directions, at v=2/3 c, will both reach stars four lightyears away in 6 years, as observed from earth (taking into account the signal delay of 4 years). Thus an observer on Earth sees the distance between the spaceships growing at 4/3 c. Relative velocity of two objects, as observed in a third FOR, can therefore exceed c. However, each spaceship will observe Earth moving away at 2/3 c and the other spaceship moving away at 0.92c.


Ok, let's do the Lorentz transformation:
Assume a rod with a pulsed lamp, light sensor, and clock at one end (A), and a mirror at the other end (B).
Within the rod's stationary frame of reference K, with proper time t and position along the rod x:
- The distance AB measures 1 lightsecond. Let A be at x=0, B at x=1.
- There are three relevant events
-- E0: Send out light pulse from A: t = 0, x = 0
-- E1: Reflect light pulse at B: t = 1, x = 1
-- E2: Receive reflected light pulse at A: t = 2, x = 0

Now let's assume an observer which moves at 2/3 c relative to the rod along the AB direction, γ ≈ 4/3
Within the observer's frame of reference K', with proper time t' and position along the rod x':
- We define E0 as the origin, t' = 0, x' = 0
- E1: t' = γ (t - xv/c²) = 4/9 , x' = γ (x - tv) = 4/9
- E2: t' = γ (t - xv/c²) = 24/9 , x' = γ (x - tv) = -16/9

The observer measures light travel at c in his own reference frame. He sees the light travel 4/9 seconds from A to B, then 20/9 seconds back from B to A.
And to show length contraction: (t=2/3, x=1) transforms to (t'=0, x'=0.75). So the observer (or two observers stationary in K', communicating with each other) will find that, at time t' = 0, the ends of the rod are 0.75 lightseconds apart in K'.

But the transformation is from what actually is to what is observed, so the rod is still length 1.0, but appears to be only 0.75 ls in length.

[happyjack27]

But the transformation is from what actually is to what is observed, so the rod is still length 1.0, but appears to be only 0.75 ls in length.

i presume that "But the transformation is from what actually is to what is observed" you mean "by what is observed from the reference frame of the rod to what is observed from the other reference frame." there is no "actually is" - all reference frames are internally consistent, and consistent with each other through the lorentz transformation. none are a priori.

[johanfprins]

Thanks guys. This is a topic that must be sorted out for once and for all. But it is Xmas and half of your children, and three of our five grandchildren, are here. Furthermore, I would like to do the derivations in detail to CLEARLY demonstrate what I am arguing about. That will take some time which I will not now steal from my grandchildren while they are visiting.

Just a closing remark: What you observe when looking at a passing rod is the position of the nose at an earlier time than the position of the tail at the instant of time you are looking at the rod. You are thus not seeing the actaul nose and rear positions of the rod at the same instant in time within your reference frame: This is not possible owing to non-simultaneity unless you can stop the relative motion and then you will find that the rod did not shrink at all. Thus, the reduced length that you see is NOT an actual reduction in the length of the passing rod. This supports krenshala's post:

But the transformation is from what actually is to what is observed, so the rod is still length 1.0, but appears to be only 0.75 ls in length.

Have a tremendous Xmas.

[johanfprins]

- all reference frames are internally consistent, and consistent with each other through the lorentz transformation. none are a priori.

I could not help to first post a remark on this. This is of course totally correct, but this supreme postulate on which relativity is based, is ignored in the mainstream literature. Since no reference frame is a priori, it means that two clocks which are stationary within two different inertial reference frames moving relative to one another MUST keep the same time within their respective reference frames: There can thus not be a twin paradox.

[mvanwink5]

Johanprins,

Just a closing remark: What you observe when looking at a passing rod is the position of the nose at an earlier time than the position of the tail at the instant of time you are looking at the rod. You are thus not seeing the actaul nose and rear positions of the rod at the same instant in time within your reference frame: This is not possible owing to non-simultaneity unless you can stop the relative motion and then you will find that the rod did not shrink at all. Thus, the reduced length that you see is NOT an actual reduction in the length of the passing rod.

You have very nicely and simply crystalized the core issue. Thank you for that and thank you for your patience. Although I understood it from the logic of symmetry and understood the measurement distortion was due to the means of measurement being limited due to the speed of light, I had failed to finish the connection to the non-simultaneity issue.

This was a very nice Christmas present. Again, thank you and Merry Christmas / and or happy holidays to you and family.

Best regards

[Teahive]

Happy holidays to you and your families.

Just a closing remark: What you observe when looking at a passing rod is the position of the nose at an earlier time than the position of the tail at the instant of time you are looking at the rod. You are thus not seeing the actaul nose and rear positions of the rod at the same instant in time within your reference frame: This is not possible owing to non-simultaneity unless you can stop the relative motion and then you will find that the rod did not shrink at all. Thus, the reduced length that you see is NOT an actual reduction in the length of the passing rod.

Certainly the rod does not shrink in its own reference frame, so someone travelling with the rod could not observe any change in the rod. But this observation isn't any more or less "actual" than the observation of a person moving relative to the rod.

It isn't quite true that you can't observe both ends at once. E.g. you could use an ultra high speed camera to capture a video of the rod passing perpendicular to the direction the camera is facing. In one video frame the rod would be centered, meaning that the light coming from both ends travels the same distance to the camera and thus was emitted simultaneously within the camera FOR (for the camera it does not matter that the light is not emitted simultaneously within the rod FOR). Alternatively you could have multiple observers with synchronised clocks, standing a fixed distance apart.


There's an interesting semantic question, though: When we speak of "length", do we actually mean "length at rest"? After all, we can measure the speed of the rod as well and compensate for it to figure out the length of the rod in its rest frame. For mass we also make this distinction.

In a similar way we compensate for signal delays. In my example with the spaceships above, the observer on Earth will only see the spaceships arriving after 10 years, but with Einstein's definition of simultaneity we still consider the spaceship having arrived four years earlier. I wonder if this definition actually makes some cases less intuitive.

[johanfprins]

This was a very nice Christmas present. Again, thank you and Merry Christmas / and or happy holidays to you and family.

Best regards

Thanks for the good wishes, I wish you and your loved ones also a great Xmas and a super New Year.

[johanfprins]

Happy holidays to you and your families.

Thanks: The same to you and your family. I will get back to the rest of your post later. Although your arguments seem logical, you are still missing the point. I am at present considering using four of Maxwell's demons to illustrate why you are missing the point. I will be back after having enjoyed the holiday with my grandchildren.

[Teahive]

Johan, I'm very much looking forward to your argument, though I will be quite busy over the next few days.

In the meantime, I read your draft "On Einstein's Non-Simultaneity, Lenght-Contraction and Time-Dilation". Unfortunately I believe it contains some crucial mistakes.

The time inverval as seen from K must then be the same as given by Eq. 4, and this implies that there must now be a phase shift: However, when the two beams arrive at the same instant at a single point within K', the physics occurring at that point must be the same at the corresponding, distorted coordinates within K. This mandates that when there is no phase-shift within K', there can also not be a phase shift within K.

I don't see why this should be the case. The Doppler effect does not imply different "physics occurring at that point" within the two reference frames.

Thus, the speed of the light-beam observed within K (when the light-beam moves towards the mirror) is [...]; which turns out to be equal to c. It is thus not (c-v)!
The speed of light relative to the mirror remains c within both K' and K.

Within K the speed is measured as c relative to stationary observers. The mirror is not stationary in K, thus within K light does not travel at c relative to the moving mirror. As I explained with the two spaceship example above, it is correct to add velocities in this case.

As incredible as it may sound, this means that just after Einstein had proved in 1905 that two spatially spearated events, which occur simultaneously within a passing intertial reference-frame K', can never be simultaneous on any of the clocks within the inertial reference-frame K relative to which K' is moving with a speed v, he used the Lorentz-transformation to map the nose-coordinates and the tail-coordinates within K' as if they have simultaneous positions within the reference-frame K.

You are making the assumption that "nose" and "tail" are events. But they are not. They are permanent, fixed positions in K'. "Event-lines" if you will.
An observer in K can see nose and tail simultaneously in K, but he would not see the same time displayed on the clocks at each end, even though they are synchronised in K'. For measuring a lenght in K, however, only simultaneity in K counts.

[Teahive]

To add some more, the concept of "measuring c", while seemingly intuitive, is deeply flawed. It's circular:

How do you measure c?
- By measuring the time it takes for light to travel a certain distance in vacuum.
How do you measure time?
- With a clock local to the observer.
How does a clock operate?
- By counting oscillations of a specific physical process.
How fast do the oscillations occur?
- It depends on c.

The last statement is trivially true for a clock based on an oscillating pulse of light, but I would suggest that it applies to any and all physical processes and systems, including clockworks, brains, and aging.

That is the reason why c must measure the same for every observer. Even if there was a hypothetical way of increasing/decreasing c in part of the universe, no one within that system could ever notice a change because their clocks and thought processes would slow down or speed up by exactly the same amount as light does. c defines time and motion.

[johanfprins]

It isn't quite true that you can't observe both ends at once. E.g. you could use an ultra high speed camera to capture a video of the rod passing perpendicular to the direction the camera is facing. In one video frame the rod would be centered, meaning that the light coming from both ends travels the same distance to the camera and thus was emitted simultaneously within the camera FOR (for the camera it does not matter that the light is not emitted simultaneously within the rod FOR). Alternatively you could have multiple observers with synchronised clocks, standing a fixed distance apart.

An excellent and correct argument, but you are still missing the point: Although your observation of the “front end” and the “rear-end” are now simultaneous within K, you are simultaneously observing where the front end was at an earlier time and where the rear end is when you are making your observation. This cannot be an actual “length-contraction” within K of the stationary rod within Kp.

Maxwell introduced the concept of a little demon with supernatural; powers to illustrate concepts relating to entropy. I am thus going to take the liberty of introducing SR-demons with supernatural powers: The latter are:
(i) The ability to communicate instantaneously with one another when spatially separated as well as when moving relative to one another;
(ii) Any one of them can stop time at any instant on his/her clock and all of them can then move around to check coordinates and times on clocks within any and all inertial reference frames;
(iii) Each one of them has an indelible pencil with which he/she can permanently mark a coordinate position within a passing inertial reference frame, which at the time of making the mark coincides with his/her own position within his/her own inertial reference frame; within which he/she is stationary.

We now assume that within the reference frame Kp within which a rod of length Lp is stationary, and we have two demons sitting on the nose and tail of the rod. Within reference frame K relative to which the rod is moving with a speed v, we have another two demons.

The demons in K instantaneously ask the demons in Kp: “What is the length of your rod?” Since they have measured it beforehand with a tape-measure, they can accurately respond that the length is Lp. The demons in K thus say: “We want to check whether this is really so. So would you be kind enough to mark the front and back positions simultaneously within our passing reference frame K so that we can measure the distance between the marks with our tape measure: Since these marks, once made within our reference frame K, will not change their positions according to our clocks, it will be easy for us to measure the distance between them with our tape measure”.

The demons sitting on the rod within Kp agree, and simultaneously mark their respective coinciding positions within the reference frame K, when their clocks show exactly the same time. The two demons within K measure the length and inform the demons within Kp: “You lied to us we are measuring a much longer length equal to L=(gamma)*Lp”. “That is impossible” reply the demons within Kp, “there must be something wrong. Are you sure you are not just stupid? Let us re-run the whole measurement while you are standing at the positions L=(gamma)*Lp apart and check again whether our indelible marks appear at this longer distance apart.” And, holy cow, the marks again appear a longer distance apart.

But in addition the two demons in K note that respective identical, synchronised clocks show different times when the marks appear within K. The demon who observed the nose mark looks at the time recorded by the demon who observed the tail mark and exclaims: “You must be an idiot since you have observed your mark appearing at a time interval (delta)T before I have observed the mark appearing for the nose”. Retorts the other one: “No you must be the idiot, or else our colleagues within Kp are holding us for fools.

Well let us stop time and measure the actual, simultaneous lengths within both Kp and K at this single instant in time So, being demons, they stop the time and thus the relative motion, and measure the length of the rod with their tape measure within both Kp and K: And holy cow, the two demons within Kp did not lie to them: The instantaneous length within Kp and K are indeed exactly the same and equal to Lp in both cases. Thus the “mistake” that appears within K must be caused by the relative motion between Kp and K . They all exclaim in unison: “How is this possible?”

So the demons decided that they must solve this puzzling discrepancy. The two demons within K thus ask the two demons in Kp to mark the position of the nose at time-intervals before the demon on the tail marks the position of the tail: And lo and behold, hey find that the time interval between the marks appearing within K decreases, until for a critical time interval (delta)Tp between the instant that the front demon within Kp makes his/her mark and this time lapse when the rear demon within Kp makes his/her mark, the marks appear simultaneously within K. “Ah! Now we must surely have the same length within K as within Kp” the demons exclaim in unison. So measure the distance between the marks within K and let us “see”.

So the demons within K measure the distance between the two marks, but, holy cow, now the distance is shorter than Lp! It is now equal to L=Lp/(gamma). Does this mean that the rod has actually shortened within K? The demons, being a bit smarter than the theoretical physicists have been on planet earth during the 20th century, realised that what they see is not the rod within Kp of length Lp contracting in length within K, but they are simultaneously seeing where the front end and rear end of the moving rod are at different times during the rod’s motion relative to K. Why is this so?

Owing to the effect of non-simultaneity, it is NEVER POSSIBLE to see the rear and front ends of a moving rod at the same instant in time within K. Thus it is utterly stupid to claim that the rod actually becomes shorter within K. Obviously, it will look shorter, but not because it has actually shrunk in length, but since, within K, at the exact same time that the rear end is observed, the nose is simultaneously observed at a position where it has been before the rear end is observed at its present position.

Now the demons are worried: When the demons in Kp simultaneously make marks within K, the marks appear at different times within K and the distance between them is longer than the length Lp of the rod within Kp. On the other hand when the demons within Kp make the marks non-simultaneously within Kp they can cause the marks to appear simultaneously within K, but now the distance between the marks is shorter than Lp. Which method should be used to define the transformed length L of the rod within K? The rod can surely not simultaneously be longer and shorter within K.

The demons within Kp suddenly have an “Aha” insight and informed their colleagues within K: “We will choose the time interval between marking the front and rear as (delta)Tpp so that it forces the length between the marks within K to be exactly equal to Lp. Thus, your problem within K is now solved: There is no length contraction at all, just as is observed when we stop time. The demons within K are not immediately happy: “But is this not contrived?”. They receive the response: “Why is it more contrived than to choose the time interval as (delta)Tp so that the marks appear within K at the same instant of time. “But” protest the demons within K, “when we look at the passing rod we can see that, at the same instant in time, the front and rear ends are at a shorter distance from each other than Lp”. “Sure” comes the response, “but what you see is not a contracted rod, since you are not able to see the actual positions of the nose and rear of the rod at the same instant in time within K. Since you know that this is so, why do you want to be stubbornly stupid to claim that the rod actually becomes shorter within K?”

“Please stop calling us stupid” respond the demons within K, “rather tell us which length is the correct length of the rod within K when the rod within Kp moves relative to us? Must we use the longer length when, although you make the marks simultaneously within Kp they do not appear simultaneously within K, or the shorter length when you make the marks a time-interval (delta)Tp apart so that they appear simultaneously within K?” The demons within Kp retort: “Why are you so obstinately stupid? We have solved the problem for you by making the marks a time interval (delta)Tpp apart so that the actual length remains Lp within both Kp and K, and this corresponds exactly to what we find when we stop the relative motion. In this case we have marked the front and rear at different times within Kp so that they also appear at different times within K, but now spaced at the correct length Lp apart. Thus, although you cannot see the front and rear end simultaneously within your reference frame, relative to which our rod is moving, the actual length does not contract, and it does not elongate.”

TO BE CONTINUED