Akinbo,

"you drive towards me and beep your horn. Both I and (R) hear the sound Doppler shifted to a higher pitch (shorter wavelength, NO"

I'm rather dumbfounded that you seriously suggest that with a known medium propagation speed, static medium and a source moving ever closer to the observer with each emission (wave OR particle) that the wavelength (distance) between them will not be less than the distance if the emitter was not in motion?

And do you insist light waves do not exist between the bulb and lens of a car headlight before hitting the moving air?

If so I fear you may be truly a lost cause to nature Akinbo. But I'm sure you'll get on fine with 'physics'.

Best wishes

Peter

Peter,

"you drive towards me and beep your horn. Both I and (R) hear the sound Doppler shifted to a higher pitch

Higher observed frequency YES, Higher resultant speed, YES, shorter wavelength, remains NO. In this regard, our lecturer was correct in saying, "Wavelength cannot change - it's a constant length in the medium, and same length in moving coordinate system (motion does not change lengths)".

I'm rather dumbfounded that you seriously suggest that with a known medium propagation speed, static medium and a source moving ever closer to the observer with each emission (wave OR particle) that the wavelength (distance) between them will not be less than the distance if the emitter was not in motion?

By the principle of equivalence or relativity, whereby what is moving towards the other can be relative, why should wavelength be unchanged in one scenario and change in the other. Throwing the boomerang back at you, do you suggest that when the observer moves ever closer to the source with each emission (wave OR particle) that the wavelength (distance) between them will not be less than the distance if the observer was not in motion?

And do you insist light waves do not exist between the bulb and lens of a car headlight before hitting the moving air?

No, light waves exist between the bulb and the lens of a car before hitting the air. But light waves DO NOT EXIST in the bulb before emission.

Lastly, what is your take on the lecturer's observed blue Doppler frequency shift for the case of an observer moving with a velocity, u towards a stationary source being quantitatively different from that when the source moves with SAME velocity, u towards a stationary observer? I don't think there should be a difference in the blue shift. But if there is, this appears to violate the relational view of space and there may then be something in it for Newton's 'Absolute Motion', i.e. a means of experimentally determining which object is doing the moving.

Regards,

Akinbo

Akinbo,

" light waves exist between the bulb and the lens of a car before hitting the air" So which 'c' do you think they are moving at. the cars? Of course. That is NOT the same c as the outside 'air's'! The difference is the car's v. The change comes as the waves are transmitted into the outside air by the glass of the lens (Maxwells near/far field transition.)

It's not an 'either or' situation with wavelength and frequency. You haven't distinguished between different observer frames. I have not suggested frequency doesn't change to an observer in the new propagation frame. Of course it does. But to measure changes between frame consistently the observer must stat y in the same frame. i.e. he CANNOT accelerate without finding different data!

Go back to the 'travelator' case, but consider standing next to the 'end' of a travellator as a line of people walking at 5kph step onto it the 'wrong' way and keep walking. You wouldn't suggest you would not see the gaps between them reduce!

THAT is the wavelength reduction (blue shift). But now consider two different observer cases. In the first you stay where you are, for a consistent understanding; You see the 'wavelength' reduce but the FREQUENCY THEY PASS YOU BY AT REMAINS THE SAME! Which is solely because the datum rest frame has changed. they still walk at 5 kph ('c').

Now jump on the travellator and stand at rest in the new frame. it is only THEN that you find the FREQUENCY has changed AS WELL AS the wavelength.

The wavelength is the real scaler quality, which changes in ALL cases. Frequency only ALSO changes if the observer CHANGES frame, to then get a REAL propagation speed which has changed from c (your original rest frame) by v (travellator speed) to the NEW local c.

You'll find the full rationale in my "Which of our assumptions are wrong" and following essays,

http://fqxi.org/community/forum/topic/1330

http://fqxi.org/community/forum/topic/1775

A very simple dynamic representation of waves moving between co-moving media is here; http://www.youtube.com/watch?v=b9KIzLuJlR0

As Einstein said;.. "...but not TOO simple..."

Best wishes

Peter

Peter,

"light waves exist between the bulb and the lens of a car before hitting the air" So which 'c' do you think they are moving at. the cars? Of course. That is NOT the same c as the outside 'air's'! The difference is the car's v".

A well reasoned reply. Now I think I see where the bone of contention is. As I said earlier there may well be wavelength change when light moves between media in different frames of motion, in this case 'the air between the bulb and lens of a car' (the entrapped air) on the one hand and 'the air outside' on the other. In that case, the car's v is also important to what happens at the observer's end. This is not the Doppler shift Pentcho and I are talking about. If you like you can call this the (Maxwells near/far field transition) and may apply to 'co-moving media'.

To see the shift we are talking about, remove the lens of the car or even the glass on the bulb, leaving only the filaments emitting the light and still drive towards the observer so that the medium (the air) is one (no co-moving media). In this case, only the frequency and resultant (relative) light velocity are important.

Your 'travellator' case is unclear to me. And your youtube titled 'time dilation' will consume my bandwidth. Your 2012 essay makes some sense as I agree 'space is not Nothing' and I may be asking Lorraine to justify her claim on 'why Quantum' that it is Nothing.

When you say, the wavelength is the real scalar quality, which changes in ALL cases. There is an inconsistency between you and the lecturer whom you previously supported, because he says motion does not change wavelength when the observer moves towards source.

All the same, we now seem to agree on two things. Cause to celebrate! 1) Space is NOT Nothing. 2) There is an Earth bound medium, call it 'plasma' if you prefer, and this is enough to prevent us from observing the Doppler frequency shift or fringe changes on Earth surface due to Earth's motion, just as Earth bound air does not allow us observe Doppler shift of sound waves from any direction due to Earth motion. No need for time dilation or length contraction.

Regards,

Akinbo

5 days later

Analogy Between Sound and Light Refutes Einstein

Professor Martin White, UC Berkeley: "...the sound waves have a fixed wavelength (distance between two crests or two troughs) only if you're not moving relative to the source of the sound. If you are moving away from the source (or equivalently it is receding from you) then each crest will take a little longer to reach you, and so you'll perceive a longer wavelength. Similarly if you're approaching the source, then you'll be meeting each crest a little earlier, and so you'll perceive a shorter wavelength. (...) The same principle applies for light as well as for sound. In detail the amount of shift depends a little differently on the speed, since we have to do the calculation in the context of special relativity. But in general it's just the same: if you're approaching a light source you see shorter wavelengths (a blue-shift), while if you're moving away you see longer wavelengths (a red-shift)."

Einsteinians are incredible sometimes. Yes, there IS analogy between observer moving relative to the source of sound and observer moving relative to the source of light, but the conclusion is that in both cases the speed of the waves relative to the moving observer is different from that relative to a stationary observer (which refutes Einstein's relativity of course):

Professor R. J. Wilkes, University of Washington: "Sound waves have speed c, and f and L are related by c=Lf. For an observer moving relative to medium with speed u, apparent propagation speed c' will be different: c'=c±u. Wavelength cannot change - it's a constant length in the medium, and same length in moving coordinate system (motion does not change lengths). Observed frequency has to change, to match apparent speed and fixed wavelength: f'=c'/L."

Albert Einstein Institute: "Here is an animation of the receiver moving towards the source:

stationary observer

moving observer

(...) By observing the two indicator lights, you can see for yourself that, once more, there is a blue-shift - the pulse frequency measured at the receiver is somewhat higher than the frequency with which the pulses are sent out. This time, the distances between subsequent pulses are not affected, but still there is a frequency shift: As the receiver moves towards each pulse, the time until pulse and receiver meet up is shortened. In this particular animation, which has the receiver moving towards the source at one third the speed of the pulses themselves, four pulses are received in the time it takes the source to emit three pulses."

"Doppler effect - when an observer moves towards a stationary source. ...the velocity of the wave relative to the observer is faster than that when it is still."

"Doppler effect - when an observer moves away from a stationary source. ...the velocity of the wave relative to the observer is slower than that when it is still."

Pentcho Valev

    Pentcho,

    "..so you'll perceive a longer wavelength. Similarly if you're approaching the source, then you'll be meeting each crest a little earlier, and so you'll perceive a shorter wavelength.."

    QED. 'Perceive' means the detected subjective reality of EACH observer. There are then TWO 'speeds';

    1) The 'closing speed', which is c/n in the ambient frame and c+v RELATIVE to any observer at any personal v.

    2) The 'propagation speed', which changes on meeting and interacting with the detector (observer) and is always the LOCAL c + v.

    The simplistic error we've made is going direct to 'f' and forgetting that nature is about real mechanisms, so about wavelength and speed changes, viewed from any rest frame ('discrete field), and not only about 'derivatives'.

    If you study it closely you'll find that better understanding a powerful tool to repair and complete incomplete theory.

    Peter

    Akinbo,

    "This is not the Doppler shift Pentcho and I are talking about." I know. That's because you have a simplified and incomplete understanding of what really generates the Doppler shift.

    "..leaving only the filaments emitting the light" Look closer. It's the same case. The filament is in a glass bulb. The light changes speed after emission, even if less that 1 micron after!.

    There's no inconsistency; I didn't support the lecturer who misses the wavelength change (and takes the shortcut to frequency) about the mechanism. It gets the same result but misleads about nature. The shortcut is then fine in use but has been exceptionally damaging to our understanding.

    EM waves cannot 'propagate' unless in a medium. If they are in a moving detectors lens/areal medium then they have changes speed and wavelength. QED.

    Time dilation and length contraction ARE Doppler shifts, so do 'exist' just not as assumed. The omission of consideration of the moving 'discrete fields' option (i.e. REAL inertial systems/frames) was where it all went off track. You'll find that applying simple 'discrete field' dynamics removes all the anomalies and paradoxes.

    Best wishes

    Peter

    Peter,

    "..a simplified and incomplete understanding of what really generates the Doppler shift"

    Many things can cause a change in wave frequency. The one you are talking about concerns changes in the medium of transmission, hence your references to refractive index, n in your later post to Pentcho. The cause of frequency change named after Doppler is due to relative motion between source and observer. That is the one under current focus. It appears you didn't read my post well because I told you to further remove the glass bulb around the filament so that there is just one medium between source and observer.

    You confuse matters by categorizing Time dilation and length contraction as Doppler shifts. These are mechanisms proposed to explain the absence of an observed relative velocity of light despite observer and source motion, mechanisms to make light velocity a scalar quantity independent of observer motion. While Doppler shift treats light velocity as a vector quantity. You redeem yourself partially by identifying two types of velocity of light in that later post to Pentcho. I, and most likely others cannot understand what you mean by, "The light changes speed after emission, even if less that 1 micron after!". What was the light speed before emission to warrant this statement? As JRC advised while you were away let us be careful with our use of words. I believe the collect word should be at.

    Regards. Hope you enjoyed your boating?

    Akinbo

    Akinbo,

    I suggest any scale 'cut off' is arbitrary above the wavelength of light. Within the bulb is the filament. If 'at rest' in an ambient medium the wavelength emitted is found as emitted.

    If it then accelerates to v wrt the medium we know very well that there are near/far field states with a 'transition zone'. This is NOT a different case. It gives a delta lambda as all radio antenna engineers will tell you! Sure it's not 'understood' as a frame change, but that's due to the theoretical confusion which produces all the paradoxes.

    Simply apply the speed and wavelength change at the TZ as in any other case of kinetic medium state change and all the paradoxes evaporate. Unfamiliar for sure, but consistently true none the less. Doppler shift is then also an entirely consistent mechanism.

    If you try to falsify that mechanism scientifically you'll find it impossible, and that it only resolves problems. It only 'confuses' WRONG theory. When consistently applied it's powers of clarification emerge. Yet it does seem to be one intellectual step beyond present comprehension. The question is; is that still a step too far?

    Best wishes

    Peter

    9 months later

    Length Contraction and Schizophrenia

    "The simplest version of the problem involves a garage, with a front and back door which are open, and a ladder which, when at rest with respects to the garage, is too long to fit inside. We now move the ladder at a high horizontal velocity through the stationary garage. Because of its high velocity, the ladder undergoes the relativistic effect of length contraction, and becomes significantly shorter. As a result, as the ladder passes through the garage, it is, for a time, completely contained inside it. We could, if we liked, simultaneously close both doors for a brief time, to demonstrate that the ladder fits. So far, this is consistent."

    Is it? An unlimitedly long ladder gloriously trapped inside an unlimitedly short garage? Einsteinians? Have you destroyed rationality in science? Einsteinians couldn't care less:

    Lawrence Krauss teaches length contraction

    Happy Einsteinians

    Pentcho Valev

      Hi Pentcho ,

      thanks for linking "the simplest version of the paradox". The coloured diagram is useful but the writer is still equating the manifestations seen with the substantial objects themselves which is not correct. The ladder, source of EM sensory data, and observed manifestation, output of sensory data processing, are distinct aspects of reality that belong to different categories of reality. These are on different sides of the Observer's Prime reality interface. Due to different observers obtaining different sensory data from the environment there is non simultaneity of events I.E they have different present experiences. Accounting for differences in dimensions of the objects observed and different reckoning of relative location of the objects in space. Thence different reckonings of when/where in relation to doors of garage. This is only paradoxical because the mathematics is not differentiating the different categories of reality. Making it seem that solid substantial objects are "magically" transformed into contradictory states of being.Where as it is perfectly reasonable that different observers produce different manifestations from differently acquired sensory data.

      The Barn Pole Paradox, Mark L Lions

      I think the next given example in the Ladder paradox, Wikipedia article (your "the simplest version of the paradox") is daft because it is talking about a man walking fast, not a significant fraction of the speed of light , and then falling down a grate. The man represented by a rod. At the speed needed for the length contraction to occur the momentum of man or rod Object would prevent him/it from falling. (Though he might trip) It seems there is no momentum in the paradox which makes it invalid.

      The last example again I don't believe it would happen,as described in the article. The rod passing through the ring due to length contraction part. - the appearance of contraction is not the same as contraction of the source of the sensory data from which the contracted manifestation was formed. Though the change in orientation of the bar when considered from a different reference makes sense. Making this example of an optical illusion rather than a paradox.

      While it is reasonable to assume there are substantial objects corresponding to the manifestations observed (Feynman Steak like) it is wrong to assume that the (sensory data)source objects are themselves exactly as they are seen. For analogy: I can see a 1cm tall building through my window (Image reality). I do not therefore assume that I can fit that corresponding substantial building (Object reality) through the crack of my open window. In fact a resident of the distant building might regard my own house as small enough to fit through an open window over there. There is no paradox in this scenario as what each observer sees is not the actual substantial building.

      The bug-rivet paradox offers an even more breathtaking spectacle:

      "In an attempt to squash a bug in a 1 cm deep hole, a rivet is used. But the rivet is only 0.8 cm long so it cannot reach the bug. The rivet is accelerated to 0.9c. (...) The paradox is not resolved."

      In the rivet's frame, "the end of the rivet hits the bottom of the hole before the head of the rivet hits the wall" - the bug is squashed. In the bug's frame, "the rivet head hits the wall when the rivet end is just 0.35 cm down in the hole" - the bug remains alive.

      Needless to say, the bug being squashed in the rivet's frame and alive in the bug's frame is fatal for Divine Albert's Divine Theory. Accordingly, Einsteinians resort to an idiotic ad hoc "requirement" - the rivet shank length miraculously increases beyond its at-rest length and poor bug gets squashed in both frames:

      John de Pillis Professor of Mathematics: "In fact, special relativity requires that after collision, the rivet shank length increases beyond its at-rest length d."

      Brian Clegg: "Unfortunately, though, the rivet is fired towards the table at a fair percentage of the speed of light. It's somewhat typical of this book that all it tells us about the speed is that γ is 2, which doesn't really give you an idea of how fast the rivet is going, but if my back of an envelope calculations are right, this is around 0.87 times the speed of light. Quite a fast rivet, then. (...) But here's the thing. Just because the head of the rivet has come to a sudden stop doesn't mean the whole rivet does. A wave has to pass along the rivet to its end saying 'Stop!' The end of the rivet will just keep on going until this wave, typically travelling at the speed of sound, reaches it. That fast-moving end will crash into the beetle long before the wave arrives. (...) Isn't physics great?"

      This physics is absolutely great indeed! The end of the rivet keeps on going at 87% the speed of light and a wave travelling at the speed of sound is chasing it in order to stop it! Here is more breathtaking discussion in Einstein's schizophrenic world:

      Abhishek Maniyar: "According to the solutions provided for bug and rivet paradox, in the bug's frame of reference the head of the rivet first collides with the wall but the end of the rivet continues to extend unless the information that the head has collided with the wall reaches the end of the rivet and so finally bug is crushed...the information goes at the speed of sound which is quite small when compared to speed of rivet..so by that time when the information reaches to the end of the rivet to stop extending,it already has expanded by a huge amount!! Doesn't it seem strange?"

      Rob Carroll: "The information does not necessarily travel at the speed of sound, but is limited by c, and even if the information is sent at this speed the paradox is resolved and both frames of reference will agree with each other that the bug is crushed."

      Abhishek Maniyar: "thanks Rob...From your explanation I understood how the paradox is resolved...but just consider this case- if the information is traveling with the speed of sound which is very small compared to speed of rivet. so by the time information has reached the bottom of the rivet it must have expanded by a 'huge' amount than its natural length... don't you think this is weird?"

      Rob Carroll: "That would be true, but the expansion would also be limited by the surface on the other side of the rivet. Another thing is that the speed of sound in a dense solid such as the material forming a rivet has a much larger magnitude than the speed of sound through air."

      Pentcho Valev

      The bug rivet paradox is again about appearances. The rivet as seen by the bug and the rivet, as would be seen by the rivet (in the setting of this paradox), are theoretical manifestations.

      The substantial rivet object itself is not a reality interface nor does it possess a reality interface so without such there is no rivet perspective. Therefore that theoretical manifestation of rivet does not exist and can not even threaten the bug.

      As soon as the rivet enters the hole; Only the Object reality, IE the substantial, absolute, reality of the rivet exists and the Image reality estimation of the bug prior to rivet's hole entry. As this happens so fast (Bug does not have time for further update or second thoughts: ). Bug is safe but it was a closer call than bugs estimate.

      My previous answer was referring to the first linked example of the paradox. At hyperphysics As I see it, even if the rivet is tiny sentient superman it still doesn't matter. Bugs can't be squashed because of the perspective given by a manifestation, an Image. Only the actualized, rather than manifest, dimensions of the substantial rivet and hole can squash it. The relative positions appear different for the different 'observers' because- if they were both observers- they would be fabricating different experienced presents from the sensory data available at their location, giving perceived non simultaneity of events.Non simultaneity of events is a perceptual difference, different experienced presents within the same absolute time. It does not affect substantial objects that are not within the perceived space-time fabrication but are always only within uni-temporal -Now, the existing configuration of the Object universe. What actually will happen is the substantial objects, material containing hole and the rivet, that are sources for both reference frame perspectives will come together and the different reference frame perspectives will cease to be relevant.

      John de Pillis Professor of Mathematics: Cute animation but he gives the bug no chance due to a longer rivet in the at rest frame.

      Brian Clegg's tale is interesting but surely the elasticity of the object upon impact will depend upon such things as the material,is it soft aluminium or titanium? and temperature affecting density, and the hardness of the table.Will the table even stop the rivet or will the head penetrate the surface at that speed? The bug could well be squashed in that case but these considerations all seem incidental to the paradox itself.

      This is the formula governing Length contraction -

      L' = L в€љ(1 - v2 /c2)

      L is the original length

      L' is the length due to moving at a speed v close to light velocity

      c is the value of light speed

      A question arises for when the flying ladder comes to rest in the garage. Does it remain contracted in the garage when it's velocity v becomes zero or does it re-expand on coming to rest?

      If the former is the case, it means it can be removed from the garage and put to flight time and time again, with a new original starting length L on each occasion. If done repeatedly, the ladder would shrink eventually to an infinitesimal or a zero length. What then would be its density? Note that this same Lorentz transformation says the ladder's mass would increase with the velocity in flight. If the latter is the case then such length contraction would be an illusion and not real since the length of the ladder cannot be measured while in flight. Why then is this portrayed as a real effect?

      How can this absurdity make sense to anyone?

      Akinbo

      Akinbo,

      "A question arises for when the flying ladder comes to rest in the garage. Does it remain contracted in the garage when it's velocity v becomes zero or does it re-expand on coming to rest?"

      John Baez & Co do give a partial answer to this question:

      "These are the props. You own a barn, 40m long, with automatic doors at either end, that can be opened and closed simultaneously by a switch. You also have a pole, 80m long, which of course won't fit in the barn. (...) If it does not explode under the strain and it is sufficiently elastic it will come to rest and start to spring back to its natural shape but since it is too big for the barn the other end is now going to crash into the back door and the rod will be trapped IN A COMPRESSED STATE inside the barn."

      It is easy to see that trapping long objects inside short containers drastically violates the law of conservation of energy. The trapped object, in trying to restore its original volume, would produce an enormous amount of work the energy for which comes from nowhere. Einsteinians don't care - some even teach that length contraction is a geometrical projection, not a physical event:

      Tom Roberts: "There is no "physical length contraction" in SR, there is only "length contraction" which is a geometrical projection -- nothing "physical" happens to the object itself."

      Pentcho Valev

        Pentcho, James Putnam, et al.

        It would be nice to hear a comment from James on how he interprets this length contraction hypothesis. Does he agree to the trapping in a compressed state or a re-expansion, which as Pentcho said will tend to violate the energy conservation law?

        For a pole 80m long (L) travelling at about .999c (v), its length would contract to about 3.57m (L'). If the barn door is opened and the pole is again put in flight again at same speed, its original length this time will be 3.57m, and its length at a subsequent trapping will become 0.16m (L"). This can go on and on till the pole becomes invisible to the eye.

        James has a nice idea concerning on the F = ma equation (Newton's second law) but why he insists on believing in length contraction is hard for me to tell.

        It should be noted that the flying pole can vary in speed as it flies, i.e. 0.999c to say 0.75c and back again to 0.999c. Does its length expand when it reduces in speed to 0.75c? If that be the case, then we should be talking of hypothetical length variation and not strictly length contraction.

        Regards,

        Akinbo

        • [deleted]

        • Post #129

        Qote :"How can this absurdity make sense to anyone?"Akinbo

        Consider that a 6m tall building can appear to become a 1cm tall building by walking away from it and then looking back at it. Without any change in dimension of the building object itself occurring. That is taken as normal and is part of everyday life- Not bizarre. How is this less bizarre than the transformation giving different apparent length contractions and different door opening/closing times from different points of view? Shrinking buildings etc. is evidence that we are not seeing objects themselves but always fabricated images of them.

        At everyday speeds of locomotion and transit of objects the image fabricated closely matches the proportions of the object [though there is also perspective] and timing of local events closely correlates, albeit with minute delay, with the occurrence of local substantial events due to the very high speed of light.

        Investigating the paradox:If a very high speed cameras are used as the observers, its possible that any blur could be digitally compressed after the events. If the different "times" of data origin are suitably identifiable(like in the colour changing pole example), it will be possible to see what different time (Object universe configuration) representations were amalgamated into the observed output. What data is received near simultaneously, from which the manifestation or the observer's present is fabricated, has a significant impact upon the theoretical image output at a significant proportion of the sped of light. Not bizarre.

        IMO The substantial objects are not changing dimension but the observers are experiencing different emergent Presents, formed from different selections of EM data. Thus disagreeing about the dimensions of observed objects and the timing of events: While still being within the same substantial configuration of the Object universe/uni-temporal -Now.

        Anonymous replied on May. 21, 2015 @ 00:45 GMT, That's me, Georgina

        Sp. "Quote"