Oops, how did the word "source" get in there?! (I'm tired...)
Of course their speed through the medium is constant. All I was trying to say is that if you are moving wrt to that medium, you will have to add your motion relative to this. Hope there is no more confusion!
Sean meant that "the speed of soundwaves depends on the speed of the observer relative to the medium of propagation".
"source" was a slip of course.
I'm reading your essay with interest...
All the best,
Flavio
The speed of the sound/light waves, relative to the observer, varies with the speed of the observer, doesn't it? Is Sidney Redner right?
http://physics.bu.edu/~redner/211-sp06/class19/class19_doppler.html
Professor Sidney Redner: "The Doppler effect is the shift in frequency of a wave that occurs when the wave source, or the detector of the wave, is moving. Applications of the Doppler effect range from medical tests using ultrasound to radar detectors and astronomy (with electromagnetic waves). (...) 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
Sean, Flavio,
It may be a very moot point wrt light as well, as you're hopefully finding in my essay.
As the source of sound is NOT also the detector the only way to get a relative speed is by calculation, of c over the flight distance.
Of course it's exactly the same with light when calculated with that same data. That's where the paradox is, because that gives c + v, yet the detector at the end of that flight path, but in the same frame as the emitter, measures 'frequency' (a derivative of effective wavelength on detection) and finds the speed at c/n wrt his lens, not c + v!!
I should say that's where the paradox 'was'. I believe it has now gone using DFM dynamic logic. Because all detectors are made of matter, and all matter is a medium, then all detectors MUST find c/n, because light MUST change speed on arrival to the new local c comply with the constant refractive index n and SR in all frames. (It works the same in a vacuum with scattering off diffuse plasma).
That may need you to lie down with your eyes shut and think through a few dozen times. I've failed abysmally to falsify the model, and found all the apparent issues with it evaporate like the SR paradoxes. Except the human factor of course, as few can overcome it's unfamiliarity. Working at Perimeter may just allow you to not reject it before full testing (I have a stack of test data).
I look forward to your comments or questions (and maybe the look on Lee's face when it's explained to him).
Thanks, and best wishes
Peter
Pentcho.
Correct but incomplete. Like saying; 'music is the variation in sound made by instruments'. It misses the critical mechanism of 'HOW'.
My post below of 20.01 was in answer to Flavio's message above. The fluctuation must have crossed the media boundary (refractive plane) and be propagating within the detector medium BEFORE it reaches any brain cells or sensors.
Old assumption, including Einstein's, was, let's say; 'incomplete'. You might well of course equally say 'wrong'.
Peter
Dear Sean Gryb,
Except for the missing negation you were correct when you wrote "depends on the speed of the source and the observer". Actually, the speed of a wave relates to the medium, neither to its source nor to observers.
This undisputed for sound fact contradicts to Einstein's relativity as well as to the emission theories that are here advocated by Pentcho and by Peter.
The key question is the interpretation of MMX. I am not the first one who understood that the unexpected null-result was actually to be expected. I merely discovered how the outcome of the MMX can be made compellingly plausible and quantitatively confirmed by Feist's experiment.
Please do not lazily ignore these arguments.
I know there are further arguments that putatively confirm either Lorentz or Einstein; in particular Maxwell's equations are not covariant.
Phipps Jr. already revealed that Maxwell's equations were adapted to the (wrong) interpretation of MMX.
Eckard
Let me respond to the many previous responses concerning the interpretation of the Michelson-Morley experiment.
I do not think it is correct to say that one interpretation is "right" or "wrong". An interpretation is an just an interpretation after all. Instead, I think it is more constructive to think of an interpretation as being "useful" or "not useful".
Einstein's interpretation was incredibly useful because it made definite new predictions, like the equivalence of mass and energy (E=mc^2), and because it led to a deeper theory: general relativity, which has been wildly successful.
It is perfectly valid to question the usefulness of a particular interpretation. That is what we are doing with Shape Dynamics and it is part of a healthy scientific discussion. However, for a new interpretation to be useful it must pass the same test as Einstein's: it must make novel predictions and it should lead to a deeper understanding. This is the challenge for Shape Dynamics and it is also the challenge for any alternative view: show how new predictions and a deeper theory could emerge from your interpretation. That is the ultimate goal of physics.
Best,
Sean.
Sean,
Einstein did not interpret the MMX. Allegedly he even denied knowing it.
Almost all physicists of that time including Hertz and Einstein accepted the as now turns out wrong conclusions from the unexpected outcome of MMX.
Whether or not the MMX disproved the aether wind is definitely not a question of interpretation but it can now clearly be decided as either a correct or a wrong conclusion.
Of course, FitzGerald and Lorentz fabricated speculative interpretations of the seeming fact in order to rescue the seemingly disproved aether hypothesis. Einstein built on these ideas his theory of SR. He incorporated length contraction and time dilution into it. Were they ever objectively measured and shown not just to be illusions explainable as Doppler effect?
I do not feel obliged to reiterate the detailed objections by opponents who questioned the ascription to SR of the many claimed predictions and confirming experiments. Some of them were already admitted in the textbook by David Bohm.
I am not the only one who considers in particular Einstein's method of (de-)synchronization and his block universe unreal and obviously flawed. I tend to at best apply the judgment by Ebbinghaus on Georg Cantor on Einstein too.
Even if you are firmly believing in Einstein's SR you might feel challenged to find an alternative explanation for my Fig. 5.
Best,
Eckard
I do not firmly believe in Einstein's SR but I find it extremely useful for solving a wide variety of practical problems and for providing a special limit to an even more useful theory: general relativity. If you have ever used a GPS you have benefited from special and general relativity. Would you discard this remarkable device as readily as the theoretical framework that led to its development?
I would if I had a framework that led to the development of even more remarkable devices. That is what I am looking for (although I will likely fail) and that would be my challenge to anyone who questions the physical assumptions of our fundamental theories.
Dear Sean and Flavio,
Interesting and well-written essay. One quick question: What exactly are the elements of the shape space of your model? Special types of 3-manifolds, I presume? Thanks,
Ben Dribus
Dear Ben,
first of all thanks for the interest in what we wrote!
To answer your question, points of shape space are "conformal 3-geometries" or "conformal 3-manifolds", that is 3-geometries (which are described by 3-metrics modulo 3-diffeomorphisms), modulo local conformal transformations. A conformal transformation preserves only angles but not
vector's lengths, so you can describe a conformal 3-geometry with just the angle-determining
part of a 3-metric. There is quite some mathematical literature on them:
http://en.wikipedia.org/wiki/Conformal_geometry
In our next paper (it's coming soon on the arXiv, stay tuned...) Sean and I found how to describe shape dynamics in the simplified case of 2 spatial dimensions with a Cartan geometry in which
the structure group is the conformal group. You have then a description of the gravitational field
in terms of "conformal frame fields", which are useful for several reasons (in GR it's easier and somewhat more natural to couple fermions to frame fields, and they provide the best known reformulation of GR as a gauge theory). Written in this way, shape dynamics looks like a Chern-Simons theory of the conformal group.
Something about Cartan geometry can be found here:
http://en.wikipedia.org/wiki/Cartan_geometry
Cheers,
Flavio
"If you have ever used a GPS you have benefited from special and general relativity." Really?
Yep.
It couldn't work just with calculations based on Newtonian dynamics.
Look at this:
http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit5/gps.html
Flavio
Btw Ben,
I've seen your essay: interesting!
Are you familiar with Rafael Sorkin's causal sets?
http://en.wikipedia.org/wiki/Causal_sets
Cheers,
Flavio
Flavio/Eckard
The assumption of SR for GPS is not verified by many of those directly involved. It was 'fudged' and rather hijacked by hard line relativists. But I agree Newton also doesn't hack it. I've written one paper on it but there are also more comprehensive ones (link by request).
Ref MMX, remember it was 'trivially' non zero. Also Millers altitude results varied. A rational solution then emerges from my essay (and paper about to be published). Einstein certainly seemed to have accounted for it - from his later paper;
"The aether-theory brought with it the question: How does the aether behave from the mechanical point of view with respect to ponderable bodies? Does it take part in the motions of the bodies, or do its parts remain at rest relatively to each other? Many ingenious experiments were undertaken to decide this question. The following important facts should be mentioned in this connection: the "aberration" of the fixed stars in consequence of the annual motion of the earth, and the "Doppler effect", i.e. the influence of the relative motion of the fixed stars on the frequency of the light reaching us from them, for known frequencies of emission. The results of all these facts and experiments, except for one, the Michelson-Morley experiment, were explained by H. A. Lorentz on the assumption that the aether does not take part in the motions of ponderable bodies, and that the parts of the aether have no relative motions at all with respect to each other. Thus the aether appeared, as it were, as the embodiment of a space absolutely at rest. But the investigation of Lorentz accomplished still more. It explained all the electromagnetic and optical processes within ponderable bodies known at that time, on the assumption that the influence of ponderable matter on the electric field - and conversely - is due solely to the fact that the constituent particles of matter carry electrical charges, which share the motion of the particles. Concerning the experiment of Michelson and Morley, H. A. Lorentz showed that the result obtained at least does not contradict the theory of an aether at rest. 1952
In spite of all these beautiful successes the state of the theory was not yet wholly satisfactory, and for the following reasons. Classical mechanics, of which it could not be doubted that it holds with a close degree of approximation, teaches the equivalence of all inertial systems or inertial "spaces" for the formulation of natural laws, i.e. the invariance of natural laws with respect to the transition from one inertial system to another. Electromagnetic and optical experiments taught the same thing with considerable accuracy. But the foundation of electromagnetic theory taught that a particular inertial system must be given preference, namely that of the luminiferous aether at rest. This view of the theoretical foundation was much too unsatisfactory. Was there no modification that, like classical mechanics, would uphold the equivalence of inertial systems (special principle of relativity)?
The answer to this question is the special theory of relativity. This takes over from the theory of Maxwell-Lorentz the assumption of the constancy of the velocity of light in empty space. In order to bring this into harmony with the equivalence of inertial systems (special principle of relativity), the idea of the absolute character of simultaneity must be given up; ..."
"Relativity and the Problem of Space" Albert Einstein (1952)
Peter
Flavio and I have both addressed the slip with using "source" instead of just "observer". The rest of the statement is true.
I can only repeat my earlier statement. I'm interested in finding the most convenient framework to explain observations and make new predictions. I believe that special relativity is useful for many purposes and has helped me personally solve many real world (i.e. experimental.. yes, I've worked as an experimentalist) problems. However, I can also accept that there are alternative explanations for these experiments. In fact, I have, with the help of collaborators, discovered my own alternative to general relativity. But the goal should be to make new predictions. Unless you can offer new predictions (or the possibility of some) I will end this discussion at that.
I called your attention to two falsehoods (slips?) in your essay but you did not say anything:
Falsehood 1: "...an experiment by Michelson and Morley that measured the speed of light to be independent of how an observer was moving."
Falsehood 2: "...the Michelson-Morley experiment led to the development of relativity."
Are you afraid to comment?
Pentcho Valev
Dear Sean & Flavio:
I enjoyed reading your well-written and intuitive essay describing the challenges in the fundamental understanding of time. You rightly point out to the two major problems that constitute the unexplained 96% of the universe - "....(dark energy) the accelerated expansion of the Universe, which is some 120 orders of magnitude smaller than its natural value.....and the dark matter problem..."
Then, you rightly state that - "...how can we do science on the Universe as a whole?
We will not directly answer this question but, rather, suggest that this difficult issue may require a radical answer that questions the very origin of time. "
My paper -" From Absurd to Elegant Universe" provides answers to the questions you raise and forwards a mathematical model of the universe as a "Whole" to resolve the well-known paradoxes of the modern science. Julian Barbour also concludes in his paper in this forum -
"....it may be impossible to understand key features of the universe such as its pervasive arrow of time and remarkably high degree of isotropy and homogeneity unless we study it holistically - as a true whole. A satisfactory interpretation of quantum mechanics is also likely to be profoundly holistic, involving the entire universe. The phenomenon of entanglement already hints at such a possibility.."
My paper demonstrates that following a holistic approach wherein the whole universe is considered as a continuum of mass-energy-space-time, a very simple mathematical model of the missing physics (hidden variable) of the well-known spontaneous decay/birth of particles can be developed that explains the observed quantum as well as classical behaviors. The holistic model also successfully predicts the observed data at all scales from below Planck scale to beyond cosmological scales. The proposed model not only resolves black hole singularities but also the unresolved paradoxes of physics and cosmology including the dark energy and dark matter. The holistic model also explains the inner workings of QM and eliminates its paradoxes and inconsistencies with relativity. It also vindicates that time is not a fundamental entity since the observed universe and galactic expansion can be predicted without any explicit consideration of a cosmic time.
I would greatly appreciate your comments on my paper. You can contact me at avsingh@alum.mit.edu.
Best Regards
Avtar Singh