John

You: is that light is the medium and waves are the features/information content of this expanding medium.

It is hard for me to figure out how can light be a medium instead of a wave. From the perspective of wave mechanics, light is a feature of the medium. The medium is the thing that exist and the wave is a feature of the medium. How can the wave be the medium and the medium be the wave? I do not get this and I do not see why to should we interchange the roles. If you have a reference in which this idea is more elaborated I would appreciate it. In any case as I understand you bring expansion as main ingredient to explain the frequency shift. Whether space or light expands I see both equivalent, because in both cases the mechanism is expansion. I clearly understand that expansion is one possible explanation of the red shift. However, in my previous posts I argue in favor of a model where there is no expansion; light loses energy simply because the aether, as any other medium, is dissipative/dispersive and light (seen as wave) is absorbed as the distance grows, just as a water wave vanishes in a lake as it propagates. My point is: why should we resort to expansion if it is not necessary to explain the observations?

Israel

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Israel,

" The medium is the thing that exist and the wave is a feature of the medium. How can the wave be the medium and the medium be the wave?"

I'm saying light is the medium and waves are features of it and its interaction with mass and the resulting measurements.

Here is an interesting interview with Carver Mead, in which he makes a similar argument for electrons and other quantum phenomena.

A water wave in an open area pool will dissipate much more quickly, as it spreads out, than one traveling down a narrow channel. That's what I mean by expansion being dissipative.

Hi John,

I am sorry I think I misunderstood what you said. Your last paragraph helped me to understand your point. As I understand your are talking about the expansion of a wave as is propagates outwards. I agree with this, the energy per unit area decreases as function of the inverse square of the distance. But there is an additional factor due to dissipation that should be added. On the other hand, one can assume, for the sake of simplification, the aether at rest, but in general it can be in motion. So this may be in agreement with you ideas.

Israel

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Israel,

I have no problem with an aether, but I think it is an effort to give space a material quality that obscures some very important factors. Consider centrifugal force; if you had an object spinning in deep space, the centrifugal force affecting something on its surface would not be due to some distant point of reference, but because of motion relative to an inertial state. I think that inertial state is also a fundamental factor in the speed of light. Light appears to travel at C, in any frame, but that is due to clocks running slower in frames in motion, which points back to that inertial state. Physics likes to say it's all about measurement and observation, but empty space isn't easily measurable or observable. That doesn't mean it should be denied, just because there are conceptual biases against it. Any more than an aether should be denied, just because it is difficult to detect.

John

Some times in ordinary language I used the word "aether" as a synonym of "quantum vacuum", "space" or "zero-point field"(ZPF), although I know that the aether has had different connotations along its history. The sense in which I mean to use the word "aether" is making allusion to the existence of a substance (which one can say that it is space itself) pervading the universe and at the same time as representative of the PSR. To be consistent we the prevailing view in physics we can convene in naming such substance the ZPF. The Casimir effect or the Lamb shift can be considered as proofs that the ZPF (i.e. space or aether, etc.) exists. Then we have a medium for light waves and this medium is slightly dissipative due to its massive nature. For relatively short distances (a few parsecs) its effect on light is negligible but at cosmological ones its effect is predominant. As to the speed of light you should take a look at my reference 17 there I explain why the speed of light is always measured to be c for any observer. So, we have the elements to hold that there is pervading massive substance.

Cheers

Israel

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Israel,

An aether doesn't explain centrifugal force. If it did, then the more an object spins, the more it would cause the aether in its vicinity to swirl and this would presumably reduce centrifugal force. Which isn't how it works. No matter how much it spins, when the object on the surface is released, it flies off in the direction it is released.

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Hi Israel,

I really liked your essay a lot. You bring up a good point about how it has been useful in the past to hunt for hidden assumptions like "a particle could obtain an infinite speed". This type of hunt is exactly what I tried to do in my own essay.

The hidden assumption that I identified was "the maximum energy scale of photon creation and annihilation (PCA) is infinite everywhere". I think that it's fair to say that this is indeed a hidden assumption that is built into both GR and the SM, and I also think that it's fair to say that past considerations of the counter-assumption (the maximum energy scale of PCA is *not* infinite everywhere) has proven fruitful (string theory).

Interestingly enough (or not), this counter-assumption could be linked to the GZK limit that you also mention in your essay. For instance, in my essay, I assume that the PCA limit at the surface of the Earth is roughly 10^19 Joules, which is roughly the same energy scale as the GZK limit. Now, I'm aware of the photopion production mechanism, and I believe that it is indeed the primary reason for the GZK limit, but perhaps a PCA limit could cause at least some of the currently unexplained dip that occurs right before the GZK limit is hit.

In any case, if you have time and interest, my essay is at:

http://fqxi.org/community/forum/topic/1482

I mentioned the cosmic ray / 10^19 Joules thing (but not in the context of PCA specifically) a couple of years ago at:

http://vixra.org/abs/1002.0009

Please keep in mind that I am not a professional physicist by any stretch of the imagination, and so I may be totally wrong with these calculations. Even if my essay is totally wrong, it is at least nice to know that someone thinks that it's possibly useful to try such hunts for the hidden assumptions. Your essay is very inspirational.

- Shawn

P.S. Daryl Janzen pointed out to me that you were working in Saskatoon. I apologize for missing that when I went through the essays earlier. I was born in Saskatoon, and I'm currently living in P.A. It's a small world, for sure. Anyway, thanks again for your essay. I really enjoyed it.

    Saskatoon seems to produce some pretty good physicists, professional or not. What's in the water up there?

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    Israel,

    "If the frequency changes for the observer in motion the wavelength will change also in the same proportion, thus the observer will measure c and not c'."

    That is what you wrote in your first reply on this thread. But this is an obvious absurdity, Israel - the observer starts moving away from the light source with speed v but the wavelength of the light chasing him automatically changes so that the speed of light relative to him gloriously remains c (c'=c-v is forbidden). Look at this video presenting the process:

    http://www.youtube.com/watch?feature=player_embedded&v=EVzUyE2oD1w

    "Dr Ricardo Eusebi: f'=f(1+v/c)"

    Do you see the wavelength changing? No? Then perhaps it is the speed of light relative to the observer that changes? Do you see that change?

    Pentcho Valev pvalev@yahoo.com

      Pentcho

      You are still totally confused. This "If the frequency...measure c and not c'." is true. Take a look at a book where you find the Doppler effect for observers in motion relative to a source at rest, and then take a look at the case in which the observer is at rest and the source in motion and work out the calculation only of the wavelength instead of the frequency. You will realize that L'=L/(1+v/c) (the sign will depend on whether the source-observer approach or move away).

      Israel

      Are Carl Mungan and Sidney Redner "totally confused"?

      http://www.usna.edu/Users/physics/mungan/Scholarship/DopplerEffect.pdf

      Carl Mungan: "Consider the case where the observer moves toward the source. In this case, the observer is rushing head-long into the wavefronts... (...) In fact, the wave speed is simply increased by the observer speed, as we can see by jumping into the observer's frame of reference."

      http://physics.bu.edu/~redner/211-sp06/class19/class19_doppler.html

      Professor Sidney Redner: "We will focus on sound waves in describing the Doppler effect, but it works for other waves too. (...) Let's say you, the observer, now move toward the source with velocity vO. You encounter more waves per unit time than you did before. Relative to you, the waves travel at a higher speed: v'=v+vO. The frequency of the waves you detect is higher, and is given by: f'=v'/(lambda)=(v+vO)/(lambda)."

      Pentcho Valev pvalev@yahoo.com

      Pentcho

      I am talking about light. You are mixing things again. The cases you are quoting are for the non-relativistic Doppler effect, that is, for other waves different from light. For light in inertial systems of reference the speed of light is always c, so if you have a frequency f'=f(1+v/c) the wavelength has to L'=L/(1+v/c) otherwise you will have c' different from c which disagrees with experience.

      Israel

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      Haha Edwin. Mostly pickerel, jackfish, and freshwater whitefish. You should stop by and cast a line some time. :)

      A simple problem, Israel: If "in a time t the number of waves which reach the observer are those in a distance (c-Vo)t, so the number of waves observed is (c-Vo)t/lambda", what is the speed of the waves relative to the observer? Could it be c'=c-Vo?

      http://www.cmmp.ucl.ac.uk/~ahh/teaching/1B24n/lect19.pdf

      Tony Harker, University College London: "The Doppler Effect: Moving sources and receivers. The phenomena which occur when a source of sound is in motion are well known. The example which is usually cited is the change in pitch of the engine of a moving vehicle as it approaches. In our treatment we shall not specify the type of wave motion involved, and our results will be applicable to sound or to light. (...) Now suppose that the observer is moving with a velocity Vo away from the source. (...) If the observer moves with a speed Vo away from the source (...), then in a time t the number of waves which reach the observer are those in a distance (c-Vo)t, so the number of waves observed is (c-Vo)t/lambda, giving an observed frequency f'=f(1-Vo/c) when the observer is moving away from the source at a speed Vo."

      Pentcho Valev pvalev@yahoo.com

        Pentcho

        You have to understand that the expressions you quote are for speeds v low compared to the speed of light. When astronomers use the formula f'=f(1+v/c) they are using it because v is low in comparison to c, but if v were much greater they would use the relativistic formula: f'=f sqrt[(1+v/c)/(1-v/c)]. The formula you quote is an approximation to this relativistic one which coincides with the Galilean Doppler formula but this coincidence does not mean that the speed of light acquires a different value from c (such as c+v), as the other wave speeds do (sound, etc.). Do not mix lines of reasoning.

        The speed of light is always c in any direction and way, it is isotropic in inertial systems of reference. Hence, if the frequency were f'=f(1+v/c) the wavelength would be L'=L/(1+v/c) so that f'L'=c.

        Israel

        I'm in if we can talk about Life, the Universe and Everything.

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        Again: If "in a time t the number of waves which reach the observer are those in a distance (c-Vo)t", what is the speed of the waves relative to the observer, Israel? Is dividing distance by time difficult? Extremely difficult? Impossible? Yes we all believe in relativity, relativity, relativity?

        Pentcho Valev pvalev@yahoo.com

        Answer:

        Speed of sound is c-Vo, speed of light c. Tony Harker is wrong, this: "and our results will be applicable to sound or to light" is false. It is misleading and confusing. If people think that this is true, they will think that for light the speed will be c-Vo as it is for sound.

        Israel

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        Israel: "Speed of sound is c-Vo, speed of light c"

        But the frequency is f'=(c-Vo)/L in BOTH cases:

        http://www.hep.man.ac.uk/u/roger/PHYS10302/lecture18.pdf

        Roger Barlow, Professor of Particle Physics: "The Doppler effect - changes in frequencies when sources or observers are in motion - is familiar to anyone who has stood at the roadside and watched (and listened) to the cars go by. It applies to all types of wave, not just sound. (...) Moving Observer. Now suppose the source is fixed but the observer is moving towards the source, with speed v. In time t, ct/(lambda) waves pass a fixed point. A moving point adds another vt/(lambda). So f'=(c+v)/(lambda)."

        See no problem? Yes we all believe in relativity, relativity, relativity?

        Pentcho Valev pvalev@yahoo.com

          Hi Guys

          Nice hearing about you again!

          Shawn

          Thank you for reading my essay and for the stimulating comments, I really appreciate them. It is a surprise to gather here three guys from the same city. Daryl and Edwin are very smart guys, you should read their essays too. It took me some time to reply because I prefered to read yours first so I have a little more background to get your comments. I found your essay well structured and focused in a specific topic. I like that.

          I fully agree that the maximum energy is an important assumption. I made this consideration a couple of years ago, derived from the fact that there must be a minimum length scale (similar to the maximum speed assumption). When I started to search in the literature for this theme I realized that there was already a theory that accounts for this. It is called Doubly special relativity or deformed special relativity. Check the article in wikipedia. This formulation was developed for flat space, and it is claimed that the theory is a particular case of the more general loop quantum gravity. I suggest you take a look at them for comparison.

          As to the GKZ limit, perhaps you may be confused, since I did not mention it in my essay. In any case, this is one of the most important problems in physics. Unfortunately, I am not aware of the details of this topic and I am afraid I could not be of great help here.

          Daryl

          I replied to you in relation to the red shift. I would be glad if you could leave me some comments. Of course, you guys are also invited to express any comment about this hot topic.

          Cheers

          Israel