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No postulate of light is violated in Galilean transformation.

  1. Jul 4, 2004 #1
    I just finished the first page of the URL at the motivation of my personal mentor, Doc Al.


    The writer showed examples of adding velocities using non photon entities. In using the photon in order to show that postulates of the speed of light would be violated if the observer shines a light ahead of his frame moving at 3/4c and adding velocities as,

    c + 3/4c = 7c/4

    This surely would a bring a contradicition of the postulates of the constancy of the speed of light limited to a maximum of 4c/4.. But wait a minute. If A is moving to the right and B is moving to the left what is their relative velocity? It is,

    v(A + B) = V(A) + v(B),

    and yes, the velocities are added to determine their relative velocity, which is greater than either velocity alone. But the writer in our example says the light was shined ahead of the moving frame moving in the direction of the light flash. To find the realtive velocity of the frame and photon entities using a standard Galilean transformation we write the relative velocity as a subtraction, or as,

    c - 3c/4 = c/4.

    So we have no contradiction of a postulate of light regarding maximum speed allowed do we, or even of measurement of the speed of light? And boy it sure seems rational that the relative velocity of the photon and frame is their difference. Do you think the writer was trying to fool us?
    I made a mistake above. The c + 3c/4 = 7c/4 doesnot vioate any postulate of lihjt. What we arediscussing here is the realtive velocity of frame and photons. An expanding velocity of 7c/4 is reasonable and rational.

    Hey Doc Al, this Galilean stuff is great, thanks for turning me on. Now I can really begin to live!!
    Last edited: Jul 4, 2004
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  3. Jul 4, 2004 #2


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    Yes it does violate the postulate of light velocity because the postulate states that the speed of light is invarient. For the speed of light to be invarient the answer you get when you add c to any velocity will must be c. (not 7c/4 or even c/4)

    The formula that perserves this, and is the correct formula for the addition of any velocities is

    [tex]w = \frac{u+v}{1+\frac{uv}{c^{2}}}[/tex]
  4. Jul 4, 2004 #3
    You missed the point. The velocity of light did not change. Nothing changed. We made a simple addition of velocities and did not vary c. When you add the observers velocity you don't change c you determine the relative velocity., simple isn't it?

    We subtracted the observers velocity from C to get c/4 a reasonable relative velocity under the conditions given. Remember the link. The writer there stated the velocity of the observer and the light was c + v, when the true or correct addition is c - v. Similarly when the observer and light are moving in opposite directions the velocity is added, v(a + B) = v(A) + v(B). In that case the relative expansion velocity is 3c/4 + 4c/4 = 7c/4. I see no violation.

    How do you add velocity? And why do ou do it your way? I opine you are thinking ahead, anticipating long memorized SR theory and aren't keeping track of the steps as you go rushing along. Tres dangereaux, n' cest pas?

    Show me where c is not measured as c. Can you do this?

    This is only an observation, but I see you giving me a mathematical formula and I give you physics arguments. Not necessarily that one is better than the other, it is just an observation. This is the error I see in this simple first step into Galilean Transformations, where light postulates are not violated.

    You see Janus you have a long way to go to arrive at your fornmula, and quite frankly, just repeating formula mantras don't cut it any more around here. You have to prove it. Do you think I don't know of your ideas, or the ideas of SR?? Get real man.:smile:
  5. Jul 4, 2004 #4
    Geist: i made a discovery in the other thread. It's looking like for every "moving observer" case all the calculations were done as "stationary observer" with "stationary sources" so that's why they believed that light speed was invariant relative to the viewer.

    such a simple mistake has set physics and astrosciences back 100 years :D
  6. Jul 5, 2004 #5
    So far, all experimental data confirms the postulate that the speed of light must be the same for every inertial observer. And that doesn't follows from your theory.

    Edit: rephrased
    Last edited: Jul 5, 2004
  7. Jul 5, 2004 #6
    We see alike. Welcome pilgrim.
  8. Jul 5, 2004 #7
    i guess that's why Tom didn't come back with the data...

    it's either that or something terrible happened to him and that would suck much, so i take the lesser "evil"
  9. Jul 5, 2004 #8
    You mean:
    "When you add the observers velocity, you don't change c"
    "When you add the observers velocity, you determine the relative velocity"

    You are still thinking c is speed of light relative to aether or something (so it doesn't change). No, c is the relative speed with respect to every observer. In other words, after the addition/subtraction/calculation we should find c as the relative speed, in order to conform to experiment results. The formula Janus gave finds c, simple addition/subtraction does not.
  10. Jul 5, 2004 #9
    Please carry out an experiment to measure the speed of light. You can't? OK, somebody else did. They found c. So it is not just calculated/believed, it was measured.
  11. Jul 5, 2004 #10
    I really don't have a theory. I referenced the link I was studying and I merely looked at the way the writer there handled addition of velocities. Your statement of experimental proof is valuless here unless you are able to discuss the experiments in detail. Can you do this, or are you just echoing SR dogma?

    http://theory.uwinnipeg.ca/mod_tech/node134.html Here take a look for yourself. This is where I am at the present.

    He stated that for an observer moving with velocty 3c/4 in the direction the observer shined his flaslight that Galilean transformation would result in 4c/4 + 3c/4 = 7c/4. I merely observed that he was adding velocities improperly. If automobiles are moving away from each other one adds the relative velocites to get maxim relative speed, right? maximum speed? If the automobiles are moving in the same direction one subtracts the velocities or 4c/4 - 3c/4 = 1c/4, which seemed like a rational and reasonable number, especially after I detected the error. If the observer was moving in the opposite direction from the light we add the velocities or 4c/4 + 3c/4 = 7c/4 which is a righteous expanding velocity form oppositely moving particles.

    Some have objected that I a violated a postulate of light, that the speed of light is always measured as c. I was raised in a morally healthy family situation and I tell you that I did not violate, nor did I alter the speed of light one tiny fraction of a m/s, trust me.

    This is very important: Measuring relative velocity with a photon and object does not vary the speed of light. The addition of velocities merely determines the relative velocity and the SR theorists must prove the contrary. You don't have to remind me that I am swimming upstream, I know it so, very clearly.

    I know that SR theorists are going to complain about this and that, they already have, like yourself, what's your story? How did you fall into the SR trap?. Well let them, this thread is titled "No postulate of light is violated in Galilean Transformation." If people are gping to respond to the thread they should keep on track, don't yopu agree?. Just saying "No No that's not allowed by SR", doesn't cut through any chaff. The SR theorists are still blinded by the simple title as I sneak through their net. I would have used Guile and Cunning but they'e still in jail on some kind of technicality thing, like a mistake, or something like that, like a misunderstanding.

    It should be a slam dunk easy as pie task to prove that what is said in this thread, by myself or any else does not conform to physical law.Those that want to trade witticisms, or preach the history if physics, as an offer of proof best have something substantial to say, other wise you will be directed, yes you, to the most brutal of task masters in this forum. Can you take it like a man, or a woman, I mean can you stand up to Doc Al when he really gets wound up and in your face? I can't, I couldn't, I had to surrender, finally.

    What you need to do to get the most from this thread is to prove me wrong, or prove yourself right, [I'll take either one, though I do have a preference.] but keep your rote SR mantras to yourself, bitte schön. I don't mean to be mean and blunt, but time is skitting along. I mean it.

    I have already been certified as "outre" if you know what I mean, so unless you have a uniquely interesting tag to place on me as a physical argument please be creative, OK? As the song goes, "I've got skin like iron and breath like kerosene, I wear my gun outside my pants for all the world to see." from "Poncho and Lefty", Willy N, et al.
  12. Jul 5, 2004 #11
    Educating Wespe: somebody has to do the hard work.

    wespe, prove it. Just don't bark SR mantras at me OK? Not this time.

    Please see where and what I was talking about. Here take a look, below, before you open your doodling fingers. Prove what you have to say. in the context of what is said. This is one step at a time, do you understand?. One step at a time. Intro to Galilean transformations 101..

    Do you hionestly think I don't know what SR has to say about velocity addition? Do you honestly believe I didn't anticipate posts such as yours?
    read and weep, wespe.
    Last edited: Jul 5, 2004
  13. Jul 5, 2004 #12
    exactly as he says. moving observer has nothing to do with the speed of light because he is not TIED to the light.

    Aether does not MOVE at the observer's velocity. there is no Aether... :D

    Light will move at "c", Calculated or Measured (if you know what you're doing <wink>)
  14. Jul 5, 2004 #13
    Prove what? Which one is the exact statement you disagree?

    Do you mean prove this statement? Experiments prove this. The speed measured in experiments (c) is relative speed of light with respect to the experiment apparatus, of course. Do you disagree?
  15. Jul 5, 2004 #14

    Doc Al

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    Galileo's secrets revealed!

    I'm glad to see you are finally learning something about Galilean tranformations! Good for you. Welcome to the wonderful world of frame swapping.

    But you are still a century behind if you think Galilean transformations describe how velocities are added in the real world. :smile: (Of course they are a wonderful approximation for low speeds.) Using Galilean transformations to talk about light is just plain silly.
    If you have secret knowledge of SR... why have you been hiding it so well in all your hundreds of posts? You sneaky devil! :rofl:
  16. Jul 5, 2004 #15
    This is the link I am looking at. I am stepping through the pages and taking them as face value. So far all I have seen ar esimple statenments that say this or that.

    I hyaven't seen anything that insist I do anything that I agree has to be done. Sying it is oart of SR isn't enough. For instance the addition of velocities follows from the statements ergarding the popstiulates of SR that are derived, at least partilly, from simultaneity conisderations.. I don't see the magic in light phenomena that says it is of such a nature that I can't move with respect to it and measure my speed with respect to the light.

    The "measurement of he speed of light" being equal in all frames comes partially from the measurement of light speed being c and partially from relativity considerations. Einstein tells us that relativity consideration imposes the restiction that we measure the speed of light the same from whatever frame measured. I just don't happen to see it thay way at this juncture.

    other rhan the relativity statement being widely recognized in SR do you see any physical reason that we allow ourselves the addition of velocities when considering stampeding elephants and Ford Futuras, but not stampeding elephants and photons?

    Soon we will be discussing the dilation of light. Read ahead in the link and see if the discussion there fits with everything you have learned regarding the propagation of light. There is a glaring contradiction from which the "dilationists" take off in wild abandon. Glaring!!
  17. Jul 5, 2004 #16


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    Geitskeissal everything in special relativty logically follows on from the 2 postulates (the invariance of the speed of light and the laws of phsyics in inertial reference frames) + pre-relativstic classical physics.

    The postulates aren't derived from anything else but experiment, the failure of simultaneity at distance needn't be considered to arrive at the formula for the addition of velocities, as both are derived directly from the postulates of special relativity.
  18. Jul 5, 2004 #17
    You quoted but didn't answer my questions...

    I didn't say speed of light is constant because of SR. I said experiments and measurements say so. Look up any experiment that measured the speed of light. All find c [within experimental error]. Plus, MMX. (dont' say Miller, you never answered my post https://www.physicsforums.com/showpost.php?p=248717&postcount=241)

    The special thing about light is that it has zero rest mass.

    Where did you get this idea? Velocity addition formula Janus gave applies to all velocities. Galilean formula is an appoximation for low speeds only.
    Last edited: Jul 6, 2004
  19. Jul 7, 2004 #18
    Janus is a robot. Hr repeats what somebody told him. He poves nothing. He attempts to prove nothing.

    Eventually we will get to time dilation, so lets do that now. We will use he link for a model. It is supposed to be educational.

    In arriving at a time dilaion result the phsics of light propagation is ignored.

    Code (Text):

    _ _______|_________
    The horizontal lines are mirrors reflecting a light pulse. Each pulse takes one second to go from floor to ceiling, or round trips take two seconds.This is a clock wih an invaiant time cycle.

    Look again at the model.

    Now if the clock i smoving to the right our model has th epulse that is recorded diffeent than he pulse in the stationary clock.
    Code (Text):
    ______________  _______________________________
               \                            /
                 \                        /
                   \                    /
                     \                /
                       \            /
                         \        /
                           \    /
            _ _______________\/____
    Ther part of he wave front being measured here is not the same as the case of the stationary clock.

    Question: Does the velocity of the source of light get added to the velocity of light?

    Answwer: No.

    Therefore the
    model we are using is bogus.

    Here is how the measurement should be conducted for a moving clock.

    Code (Text):
              |     |
              |     |
              |     |
              |     |
              |     |
              |     |
              |     |
              |     |
              |     |
              |     |
     _______|___ |_________      
    The two lines ,the right one "down" the left "up", should be supperimposed on each other and shown separate for instructional puposes. It is the frame that moves. Right? Isn't this the law of he propagation of light? Answer:yes.

    Using th extended light ray as indicated in this linkis the corruption on the construction of time dilation, all followed so robotically by the masses of SR theorists that wanna be.

    Next post how to make a light clock that works. Stay tuned.

    Responders, if any, please use the laws of physics in your posts.
  20. Jul 7, 2004 #19

    Tom Mattson

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    Janus proved that you have no idea of what the postulate of the speed of light says, or what "invariant" means.

    This is so badly mistaken, I can hardly believe that anyone who claims to have studied any physics could say it. Time dilation comes from precisely a very careful consideration of the physics of light propagation. You've demonstrated over and over again that you don't understand how light propagates anyway, so I guess I shouldn't be too surprised at this.

    No, it's your logic that is bogus. The assumption you are tacitly making is that the Galilean velocity addition formula should hold. But it doesn't.

    Janus tried that, and you called him "robot". So what's the use?
  21. Jul 7, 2004 #20
    It turns out how light travels [direction]* is not totally independent from the source if the source is moving perpendicularly (this is something I didn't think clearly before, thanks). But, still, speed of light must remain the same, because otherwise you could send a message faster than light.

    Suppose light source is stationary and a message is sent from A to B in 1 second.

    Code (Text):


    Now, the light source is moving perpendicularly. According to the stationary observer, light is travelling diagonally, but it must still travel the same distance in 1 second:
    Code (Text):

            A     A'

    distance from A to C is longer, so information can't be sent in 1 second. It should take more time (hence the time dilation)

    According to the moving frame, light traveled perpendicularly, but it was C that moved to the old position B, so it still took 1 second:

    Code (Text):

    _______  <-C________
    Of course, when the first case is viewed from the moving frame, all of this is observed the other way, so both frames see each other's clocks running slower.

    Ultimately physics is an experimental science.
    see http://hyperphysics.phy-astr.gsu.edu/hbase/relativ/twin.html#c0
    How will you explain these results if time dilation is bogus?

    edit: (*) I have thought of light as a photon particle above. There's also aberration of light which I don't know exactly. Also there's wave/particle duality but we enter Quantum theory there. So I'm not 100% sure about this.
    Last edited: Jul 7, 2004
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