Bart
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Posts posted by Bart
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OK, I'll try to answer your question: The answer is no. The speed of light in a glass rod will show no difference, whether the rod is parallel to the Earth or perpendicular to the Earth. This result does not violate special relativity. Why? Because it is being performed in a single frame of reference. The source of the light, the glass rod, and the device which measures the speed of that light are all on the Earth at rest with respect to each other -- i.e. in a single frame of reference.
The motion of the Earth has no effect because the entire experiment and the Earth are moving together. This, in essence, is what Galileo said in his Dictum on uniform motion.
(There is a caviat here. We are assuming here the Earth is moving in uniform motion -- no change in speed and/or direction. The spinning of the Earth around its axis and the motion of the Earth in its curved orbit around the Sun are not uniform motion. However, there effects are so small in this experiment as to be considered negligible.)
Thank you IM for your reply. But if the speed is unchaged because the source of the light, the glass rod, and the device which measures the speed of that light are all on the Earth at rest with respect to each other -- i.e. in a single frame of reference, then it will be the same if all that stuff will be placed in a rocket and launch to space with the speed eg. 0,5 c. Am I right?
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Given that, your supposition in post #11, "If this were true, we could measure e.g. the speed of rotation of the Earth, by measuring differences in velocity of light in a glass rod (flint 170 000 km / s) in the parallel direction to the Earth's movement and in the transverse direction to this movement.", is incorrect.
You are the one making extraordinary claims. The burden of proof lies upon you to justify your claims.
Since no one dared to answer this question, we can only assume that the matter lies elsewhere.
Because, regardless of whether for the case presented, the response will confirm or deny the unchanging speed of light in the glass rod, BOTH ANSWERS WILL DENY THE CREDIBILITY OF THE SR THEORY.
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Yes, it is difficult to grasp because it is nonsense.
Where is the observer, where is the rod, how long is the rod, what is the velocity of the rod with respect to the observer? How is the experiment to be performed? How are you measuring one-way speed of light in this rod?
Evrything is in a physics laboratory. The light source, the test apparatus, and the detector are all at rest with respect to each other (and the Earth.) The glass rod you can have as long as you need to answer the question.
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Clear as mud.
Describe your proposed experiment, in detail.
Sorry DH once more, I can not describe my question more detailed. Is is really so dificult to grasp the problem, I am asking?
Whether measurements of the speed of light in a glass rod (flint 170 000 km / s), will show the difference of speed, if the first measurement of the speed will be executed when the rod is in a position parallel to the speed of the Earth, and the second measurement, when the rod is in a position transverse to the motion of the Earth .
Does the speed of light in a glass rod (or other medium) depends on the motion of the Earth?
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I have a kind question, why my yesterday's post disappeared from this forum without any response ?
Post concerned the credibility of SR theory and the question in the following issues:
Whether measurements of the speed of light in a glass rod (flint 170 000 km / s), will show the difference of speed, if the first measurement of the speed will be executed when the rod is in a position parallel to the speed of the Earth, and the second measurement, when the rod is in a position transverse to the motion of the Earth .
Does the speed of light in a glass rod (or other medium) depends on the motion of the Earth?
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Nonsense. I said nothing about the motion of the medium relative to the source because the motion of the light source is immaterial.
Re "it could measure the speed of the Earth": What is "it"?
Re "velocity of light in the glass": What glass?
Be a bit more transparent in your writing. You are paying so much attention to appearance (font and size) that your writing lacks substance.
Sorry DH, I repeat:
If this were true, we could measure e.g. the speed of rotation of the Earth, by measuring differences in velocity of light in a glass rod (flint 170 000 km / s) in the parallel direction to the Earth's movement and in the transverse direction to this movement. I hope it is clear enough, now.
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It's nonsense because the author is misinterpreting the Michelson Morley experiment and because his "unreal" phenomenon is very real. That the speed of light through a medium depends on the velocity of the medium with respect to the observer was first demonstrated in 1851 in the Fizeau experiment. The Fizeau experiment is an after the fact confirmation of special relativity.
In the Fizeau experiment, the medium was in motion relative to the light source. Your explanation is not true for the medium without movement relative to the light source, so your arguments are wrong. If this were true, it could measure the speed of the Earth by measuring the differences in velocity of light in the glass in a direction parallel to the motion of the Earth and in the transverse direction.
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If the speed of light in air, shown by the Michelson-Morley experiment and in later experiments, is indeed constant in every direction and not depend on motion of the Earth, it is also legitimate to say that the speed of light measured in stationary water (~230 000 km/s), or glass (~170 000 km/s), also must be constant in each direction and independent of the speed of light source. If that were not true, it would have discovered long time ago, and then would be possible to construct universal speedmeters, based only on changes of the light speed, which is unreal.On the other hand, if as shown, the speed of light is independent of the direction and of the movement of the light source, for each medium, then the light-clock uses eg. glass, in a rocket moving with any speed, will always indicate the same time as on Earth. Thus arguments of the special theory of relativity, about for example time dilation, are wrong.
This is utter nonsense. The premise of special relativity theory is that the speed of light in vacuum is the same to all observers. Special relativity says nothing about the speed of light through matter. Getting a complete picture of how light interacts with matter took another than 40 years after Einstein's 1905 paper. You might want to study quantum electrodynamics, not some crackpot nonsense on the internet.
Could you explain what is this nonsense? Do you think that the speed of light in glass or stationary water is not the same in all directions and is dependent on the motion of the Earth? When and how it was found?
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On thelink: http://dl.dropbox.com/u/26262175/InterpreatationMichelsonExperiment.pdf
is presented the analysis of the Michelson-Morley experiment, which shows that this experiment could be misinterpreted.
Thus, whether the SR theory was based on false premises?
Has anyone checked this already?
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Measurements made in a laboratory on Earth have shown that the speed of light measured in the air is constant in every direction and does not depend on the speed of the Earth (speed of the measuring interferometer).
So will be right the conclusion that measured, in the same laboratory, the speed of light in the motionless water or glass, will also be constant in any direction and independent of the speed of movement of the Earth?
Best whishes of happinesses and successes to All in the new year has already begun!
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As pointed out, nothing. In the rest frame of the rocket nothing has changed. In the frame where the rocket has a relative speed of 0.9999 c, The rocket behaves as a version of the rest frame that is shorter, time runs slower, and has a different notion of simultaneity. IOW, nothing untoward happens to the rocket (the rocket doesn't balloon out from increased pressure, etc) in the rest frame or any other.
Don't think about Relativistic effects as something that actively compresses objects or forces their internal movements to slow down.
Relativistic effects are just due to the fact that different inertial frames view and measure time and space differently from each other.
Thanks for your comments. I am now totally confused in these Earth explanations.
As apassenger, I now travel a rocket at a constant speed 0.98 c in relation to the Earth and I do not feel for this reason, any changes in my surroundings here. Just as on the Earth, I still have 180cm height and 80kg mass, my soccer ball is still round, and my dumbbells have weight 5kg. The only difference is that I see you on the Earth in a more red color due to your fast moving away from me (Doppler effect) and I hear your radio broadcasts more and more delayed, which is also understandable because of the increasing distance.
But I hear, that you there on the Earth, you say that my mechanical watch is five times slower than on Earth, and that I have now only 30 cm tall, that I have a mass of 400kg, that my soccer ball has now become a rugby ball, and my dumbbells have a mass of 25 kg and which I still brandishes as fast as on Earth. Is it in your view, that my strength also increased 5 times?
Neither you on the Earth nor I in the rocket are able to determine who of us is at rest and who is moving at speed of 0.98 c. We move away from each other with the speed 0,98c and that's all.
Neither your seeing me and not my seeing you, has no effect on the actual physical state of whoever of us. The relativistic effects are just an illusion, caused by the limited speed of transmission of the information (light speed). If we ever find a data transmission method much faster than light , then the present illusion at the speed of light will disappear, and the current supposed evidence of mass increase, time dilation,etc. prove to be only a measurement or interpretive errors.
I believe that sooner or later it will happen.
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Assuming that the idea of relativistic mass density is a valid concept, You would simply take the relativistic mass of the object per the gamma relationship divided by the volume per length contraction. Thus if the relative speed is 0.886 c, the length and thus the volume would halve, and the relativistic mass double, giving 4 times the density.
Then if the relative speed is 0.9999 c, the length and thus the volume would be contracted 70 times, and the relativistic mass increases 70 times, giving 5000 times the density.
1. What will happen then with the Mendeleev's Periodic Table of Elements?
2. What will be the speed of light, eg in air or water, when its density increases 5,000 times?
3. What will happen with the air pressure in the cabin of the rocket and what happens to the rocket itself, when the density of the rocket and air contained therein will grow 5,000 times ?
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1.His first argument is something we've already gone over and is easy to dismiss by the actual results from accelerator experiments. If the argument was true, particles leaving the accelerator would have much less energy than predicted by Relativity. Since we can measure the energy of these particles after they leave the accelerator and their energies equals those predicted by Relativity, the argument fails in the face of the physical evidence.
2. It is like arguing that rockets won't work in the vacuum of space because they would have nothing to push against. No matter how much you may believe that your argument is correct, the fact that real rockets in the real world do work in space makes it a pointless argument.
3. The second argument trying to link relativistic mass increase and length contraction is just silly. The idea that the density of the mass as viewed from different frames, must remain the same is misguided.
1. "Any number of experiments can not prove that I'm right: one experiment may show that I am wrong ". A. Einstein
2. A rocket is propeled by its own jet engine and not by an external system like protons in accelerators, so the above comparison is wrong.
3. What then is the formula for the increase of relativistic mass density? Does the density of mass can grow in a different proportion than the contraction?
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Relativity is mathematically self-consistent, which means that any thought experiment cannot contradict itself. If you get a contradiction, you've done the math wrong. What the author has done in a few places is double-count the effects of relativity. It's crap. It lacks any comparison with experimental results, which is the only way you can falsify a theory.
The first section hasn't suddenly become correct since it was discussed a month ago
What energy is measured in accelerators? Is it the energy of the particle mass, or the energy that is generated by the charge of this particle in motion? Since they are two different things. When measuring the energy generated by the charge, the cumulation of its may occur, distorting the measurement, similar to the cumulation of acoustic energy when approaching a sound barrier.
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Interesting explanations with the surprising conclusions regarding the interpretation of the SR theory, are shown in the link:
http://dl.dropbox.com/u/26262175/TransparencySRtheory.pdf
Has anyone already seen it? What can be think about the explanations presented there? Can they be true?
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219749 kps is the speed of the light traveling on the diagonal relative to the the rest observer, which resulted from using the orthogonal velocity addition formula. For the lengthwise clock you have to use the standard velocity addition formula:
[math]\frac{u+v}{1+\frac{uv}{c^2}}[/math]
Again notice that if u=c (as for the light clock in vacuum) then the answer is always c.
However if u = 170,000kps,(glass light clock) then for the light traveling in the direction of v (fro v =169,000 kps) you get:
~256970 kps
and for the light traveling in the opposite direction (after being reflected), you get.
~-1470 kps
(the minus indicates that the velocity of the light is in the opposite direction.)
Notice that unlike when the light travels at c, these two speeds are different.
Once you factor in length contraction, you can determine how long it would take the light with these speeds to travel back and forth between the mirrors of the light clock according to the "stationary" observer. If you do the math, you will find that is is consistent with the standard time dilation prediction.
I will go further. No thought experiment of this type can ever expose a flaw or internal contradiction in SR. If you think you've found one, you have made a mistake or misapplied the theory. It is internally consistent in all ways.
This does not mean that SR could never be overturned or found in need of correction, but just that the only way to show this is for real life experiment or observation to give a result that is in conflict with what SR predicts. Attempts to disprove SR by thought experiment are doomed to failure from the get go.
Janus, thank you very much again for your clarification. You are a very patient guy, and you made hard work, thanks. Math is correct now, but the reality seems to be a little simpler. Thank you all for your posts.
Bart
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Again, whenever we talk about the speed of light being the same for all observers, we are only talking about the speed of light in a vacuum. We call this speed "c". c is always equal to 299,792,458 m/s. There is nothing special about light itself, only c, which happens to be the speed light travels in a vacuum. So if you ever have an equation, such as the time dilation formula or the addition of velocities formula, which has "c" in it you can only use c in that formula. You cannot, as the author of the link did, simply replace c with Cs, the speed of light through a medium other than a vacuum.
If you want to determine the time dilation factor for a clock in which the light passed through glass light clock, you have to use the velocity addition equation that I gave in the last post to find the speed of the light on the diagonal according to the "rest" Observer. So if the speed of light through the glass is 170,000 kps and the clock is traveling at 169,000 kps then the speed of the light on the diagonal would be ~219749 kps. You would then use this speed And the Pythagorean theorem to determine the time dilation for the light clock. If you did so, you would arrive at the same relative time dilation as you would using a standard light clock.
Thank you Janus for clarifying. But even with the adoption of the calculated speed of light for the glass clock as 219749 kps, it still does not agree with the lengthwise clock.
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Your understanding is wrong. Relativity is based on the fact that there is an invariant speed ©. Now. it happens that light travels at c in a vacuum, which it is convenient to use light in examples, but only if we use light traveling in a vacuum. For example, we can always assume that light in a vacuum travels at c relative to any frame. If we use the light clock example, we came use the addition rule for orthogonal velocities:
[math]w = \sqrt { v^2 + u^2 - \frac{v^2u^2}{c^2}} [/math]
For the light clock in a vacuum, u=c, and w always equals c no matter what v is. If u is equal to .567c, then W varies according to v (Cs is not invariant). This does not mean that you cannot calculate the time dilation, just that you can't use the formulation given in the link which treats Cs as invariant. If you do do the calculation, you will get the same answer as standard time dilation gives.
Iam very sorry, but I still do not understand this question. Please, explain how time dilation will be seen by an observer on the clocks in the following description, taken from Wikipedia, and assuming that there are two light clocks side by side, a vacuum clock and the other glass clock.
Simpleinference of time dilation due to relative velocity http://en.wikipedia.org/wiki/Time_dilation
Observer at restsees time 2L/c.
Observer movingparallel relative to setup, sees longer path, time > 2L/c, same speedc.
Time dilation can be inferredfrom the observed fact of the constancy of the speed of light in all referenceframes.[2][3][4][5]
This constancy of the speed oflight means, counter to intuition, that speeds of material objects and lightare not additive. It is not possible to make the speed of light appear fasterby approaching at speed towards the material source that is emitting light. It isnot possible to make the speed of light appear slower by receding from thesource at speed. From one point of view, it is the implications of thisunexpected constancy that take away from constancies expected elsewhere.
Consider a simple clock consistingof two mirrors A and B, between which a light pulse is bouncing. The separationof the mirrors is L and the clock ticks once each time it hits a givenmirror.
In the frame where the clock isat rest (diagram at right), the light pulse traces out a path of length 2Land the period of the clock is 2L divided by the speed of light:
Fromthe frame of reference of a moving observer traveling at the speed v(diagram at lower right), the light pulse traces out a longer, angledpath. The second postulate of special relativity states that the speed of lightis constant in all frames, which implies a lengthening of the period of thisclock from the moving observer's perspective. That is to say, in a frame movingrelative to the clock, the clock appears to be running more slowly.Straightforward application of the Pythagorean theorem leads to the well-knownprediction of special relativity:
Thetotal time for the light pulse to trace its path is given by
Thelength of the half path can be calculated as a function of known quantities as
SubstitutingD from this equation into the previous and solving for Δt' gives:
andthus, with the definition of Δt:
whichexpresses the fact that for the moving observer the period of the clock islonger than in the frame of the clock itself.
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then whats the question?
The question is: what difference of time these clocks will show per day (24h), according to the theory of relativity?
In my understanding the clocks will always indicate the same time, regardless of their distance and period of time measurement, day, year, 10 years ... But what about the theory of relativity?
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what do you mean by timed remotely?
you mean you measure how much time each records?
Clocked remotely means that the clocks are driven by pulses from 1 GHz radio transmitter, and not their own oscillators.
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its not a strange question at all.
http://www.iopb.res....ity/node75.html
A direct measurement of gravitational time dilation requires measurement of time delays between two clocks which are placed at different gravitational potentials. An example would be two clocks, one placed in a satelite and another on the surface of Earth. Let us compute the difference between two clocks, one placed on Earth and another at a distance of twice the radius of Earth
That is, in a day the two clocks will show a time difference of about 30 microseconds in one day. Such small time differences can be observed in atomic clocks.
http://www.physicsfo...ead.php?t=58359
escape velocity of earth = 10 km/s (actually its 11.18 kilometers per second)
at that velocity gamma = 1.000,000,000,556,325,2
gamma calculator
Thanks for your response. But this question is strange, because I forgot to add that the two clocks are timed remotely from a radio transmitter 1 Ghz, installed on the slope.
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Suppose that at the top of Mt. Everest precision clock has been installed, and the same second clock was installed at the bottom of the mountain, 8 km below the summit.
Before installing, clocks were carefully synchronized.
The question is: what difference of time these clocks will show per day (24h), according to the theory of relativity?
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Just some more detailed points in regards to the flaws in the linked paper.
1. In the formulas for clocks 3 and 4, the author simply replaces c with Cs (assumably the speed of light in the glass). This is incorrect as the formulas using c are based on the idea the c is invariant, and Cs is not. The proper formulas would have to reflect this and incorporate the velocity addition formula.
2. Simply applying the Doppler shift formula and plugging in the velocity of the rocket does not give you the time rate difference between the clocks. Instead, what you need to do is to calculate the total accumulated time for both clocks over the course of a round trip of the rocket. (and if you do, you will find it in complete agreement with time dilation. )
3, The formula given is fine for the time as measured in the rocket, but fails to take into account any relativistic effects. A proper analysis of the period of the pendulum would have to take into account the effect of the velocity addition theorem on the pendulum bob. In addition, when the author "corrects" for length contraction, all they did was shorten the length of the pendulum arm and reapply the period equation. Since the arm of the pendulum would not always be parallel to the motion of the rocket, length contraction on it would not constantly act along its length. (in other words as the pendulum swings from side to side, the length of the arm would vary. The author oversimplifies a complex problem and as a result come to the wrong conclusion.
1. In the calculation using the glass clock has to be applied to the speed of light in glass (Cs), and not in a vacuum and in my understanding the formula used by the author is correct
2. I do not understand your objections, may I know on what formulas is obtained the same time of the clocks? My calculations show that for the trip there (T1) and back (T2), total time measured by the clock based on the Doppler effect by the formula: T1 + T2 = 1 / (for * ((1-v / c) / (1 + v / c)) ^ 0.5) + 1 / (for * ((1 + v / c) / (1-v / c)) ^ 0.5), will always be greater than for the vacuum clock based on the relativistic formula: T1 + T2 = 2 * (2D1 / c) / (1 - (v / c) ^ 2) ^ 0.5, and it is for any speed of the rocket.
3. It is true that the author simplifies the calculations for the pendulum, but it has little effect on that the clock is fast, but it does not affect the correctness of conclusion.
4. "Whether or not such an test has actually been done on the ISS is moot, since the sameexperiment is essentially done every day with GPS satellites. The clocks onthese satellite have to be adjusted to compensate for time dilation in orderfor the system to remain accurate."
Correction of time of GPS clocks, is that the clocks are fast and not late, and this may be the result of the following two circumstances:
- To take account the orbital speed of Earth. See calculations by Professor Joe Nahhas http://www.scribd.co...-is-an-illusion
- The need for constant adjustment of time of the satellite clocks due to the slow degradation (shortening) of satellite's orbits.
Thus, the GPS does not need to be a reliable evidence of time dilation.
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That gives results that quantifiably match the predictions of Relativity across a wide range of velocities? That seems a lot like grasping at straws.
I don't know where you got the 60 km figure from. The majority of muons are created at an altitude of 15 km. But even if we use the 60 km distance, we are talking about half-lives. So after traveling 33 km, half of the muons would be left, after 66 km, 1/4 would be left, etc. Compare this to the nominal half-life of 2.2 us. Half would be gone after only 660 meters, 1/4 would be left after 1.32 km, 1/8 after 1.98 meters. After 60 km, an extremely small number would be left compared to the amount expected with time dilation.
Thanks Janus for your reply. The 60 km I got from the link given at IM Edgall's post, as below:
"Fro example, see link: http://www.physlink....perts/ae611.cfm "
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The theory of relativity has become not credible?
in Speculations
Posted · Edited by Bart
Sorry DH, I am not criticize the subject only I want to explain my doubts. I think we do not understand each other, because your answer do not explain my question. I have learned SR, may be as deep as you but I am not so happy follower of that theory as you might expect.
Can you be so kind to answer my simple question putted in the post #25 to IM?