Is relativity self-contradictory??

Discussion in 'Physics & Math' started by Prosoothus, Aug 30, 2002.

  1. c'est moi all is energy and entropy Registered Senior Member

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    583
    "Illogical, no. Counter-intuitive, yes."

    It is not counter-intuitive. You sit in the train, the other starts moving, but you don't know, it feels like you start moving. Is that counter-intuitive? It's just wrong: do you agree with me that the human body and its senses is not much of a champion compared to other animals? If you'd have better developed senses, you would perfectly know if you were moving or not, regardless of the other train moving. You might for example feel that the wheels below you aren't turning, etc.

    Do you agree with me that space has a structure? If your senses would be even more developed, maybe you'd feel the structure around you, just like you can feel a soundwave of a bass resonating in your body. The theory of relativity is an attempt of filling the gap of our shortcomings as observers. That's why many people tend to resist to it. It yields correct results but it's not the whole truth. Philosophically it is incorrect.

    "But the fact that you think it's hard to understand is no reason to believe it's wrong. "

    it's not hard to understand
     
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  3. Tom2 Registered Senior Member

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    726
    My equations are relativistic because I assume that the speed of light is the same in both directions. I have pointed this out over and over again, and you are still ignoring it.

    You claim to adopt the Newtonian/Galilean scheme, and you also claim that you can derive time dilation from it. That is simply not the case, as I have shown. When one further considers that time and space are completely decoupled in the time transformation (IOW, t’=t), your analysis is again overturned.

    And I still am.

    Look in the mirror, bub.

    I always respond with logical arguments, or at least a reference that contains the argument I wish to present. Over time, I would get responses from you such as “that’s stupid” or “If you don’t see what I’m talking about then I feel sorry for you.” Finally, in this thread you set out to prove that relativity is self-contradictory. I correctly refuted you. Rather than address it, you accused me of dishonesty and called me an idiot.

    You set the tone for this, not me. But I am willing to start from square-one if you are.

    No one expects you to have a PhD—just a willingness to learn. That means, among other things, reading up on the subjects you wish to critique. It also means that you have to get out of the habit of saying that something is “stupid” or “illogical” for no other reason than that you find it personally distasteful.

    Claim? No, Tom, I have demonstrated that your analysis is wrong. I don’t claim things like that, I show them.

    1. I have not seen overdoze’s presentation.
    2. It’s not that the equations are wrong, it’s that they don’t say what you want them to say.

    I am not disappointed, because I don’t think it’s that tough either.

    First, you have yet to show that relativity is “illogical”. Second, you have yet to see that it is not relativity, but only your misunderstanding of it that is “illogical”.

    Without question, SR is counter-intuitive, but that doesn’t mean that it is self-contradictory. Common sense is not an acceptable guide in science, because it is a notoriously unreliable one.

    When you say “breaks down”, that means to me one of two things:

    One, there is something wrong mathematically (divergence, multiple-valued function, etc). In that sense, SR does not break down at all except in one circumstance: a massive particle traveling at the speed of light. From this we draw the inference that such a situation is impossible, according to SR. However, there is no self-contradiction here. I contradiction ensues when an argument contains two premises that cannot both be true. Given that, SR has no logical contradiction, because both postulates are independent of each other.

    Two, “breaks down” can also mean that some experiment has been done that runs contrary to the predictions of SR, and I know that this has not been done.

    So, if you care to support your statement above, I will show you why it is wrong.

    That said, there is a sticking point with relativity and the one-way speed of light. No experiment has been done to verify that the speed of light is independent of the speed of the source, so this postulate remains unconfirmed—but that does not mean that SR is self-contradictory. The problem is this: there is another theory of relativity which has a frame of absolute rest, and which predicts the same results for the two-way speed of light that SR does, but does not postulate that the speed of light is independent of the speed of the source. However, this theory is not the Newtonian/Galilean one that you claim to agree with.

    Galilean relativity goes like this:
    Premise 1: There is a frame of absolute rest (the “aether”).
    Premise 2: The laws of mechanics are the same in every inertial frame.
    Conclusion: The Galilean Transformation

    The trouble with this scheme is that it leaves electrodynamics out in the cold. The EM wave equation is not Galilean-covariant. That this scheme is wrong is verified every time you are driving in your car and listening to the radio, because if you are moving relative to the source (radio transmitter), then Galileo says that for you that transmitted wave is no longer a traveling wave, so it should never come to your antenna in the way that it does. Thus, Newton/Galileo is demonstrably incorrect.

    Lorentz supplied the additional premise of length contraction, and with it he developed a valid scheme that agrees with SR in the over-and-back measurements of the speed of light. However, Lorentz’ theory was discarded because it is far less economical and it seems to be less plausible—two totally subjective judgments, to be sure.

    The one-way measurement of the speed of light in two different frames will determine whether Einstein or Lorentz is correct. However, you should be aware that time dilation and length contraction are unavoidable aspects of either scheme.

    I have studied these theories for a long time. One of the great things about a forum like this is that you can take advantage of the experience and knowledge of people who actually do research in the field—but you have to listen and think.

    That isn’t going to happen. Yes, I think you refuse to learn this stuff. I think it is clear from, among other things, the fact that you are still saying that relativity introduces length contraction and time dilation to compensate for the speed of light postulate. A serious reading of any derivation of relativity will reveal that this is simply not the case, and I have linked you to just such a derivation.

    I can only conclude one thing: that you never bothered to look at it.

    However, I think that you can learn relativity (if not, I would not have bothered to present the link). But even if you never do change your stance on learning relativity, I am still going to respond to your posts. I meant it when I said that your posts are potentially harmful stumbling blocks to people who sincerely want to learn from this forum. That’s why I think your posts should be refuted, and that you should re-consider them in the light of what is being said to you here—not only by me, but also by James R, (Q), thed, etc… You have received some terrific feedback in this forum, and you have yet to really capitalize on it to advance your understanding—but it’s never too late to start.

    Tom
     
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  5. Tom2 Registered Senior Member

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    726
    Well, the proper distance to the galaxy is 3 million ly no matter how fast you are moving—that is how it is defined. I’m not too sure if the rest of your case depends on that, though, so it may not matter.

    Funny you should mention that—I am just now preparing to sit down and get serious about the following document, entitled “Marzkhe-Wheeler Coordinates for Accelarated Observers in Special Relativity.”
    http://xxx.lanl.gov/PS_cache/gr-qc/pdf/0006/0006095.pdf

    Until I get though it, I’m not too sure how to handle the problem, so it seems you’ve caught me with my pants down. It’s a tough problem, to say the least.

    Are you saying that the galaxy is moving away from your origin at a rate that is greater than 3E8 m/s as measured by you? Or are you saying that the rate of recession is >c in the same sense that superluminal jets move apart at a rate that is >c?

    Tom
     
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  7. Crisp Gone 4ever Registered Senior Member

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    1,339
    This sounds new to me...

    Hi Tom2,

    "Galilean relativity goes like this:
    Premise 1: There is a frame of absolute rest (the “aether”).
    Premise 2: The laws of mechanics are the same in every inertial frame.
    Conclusion: The Galilean Transformation"


    Could you cite a reference on this please ? I remember my textbooks on Galilean transformations never mentioned anything about an absolute frame of reference. In fact, I remember vividly that even Newtonian mechanics is a relative theory, in the sense that there is no prefered frame of reference (that must be why they call the transformation principle the "Galilean principle of relativity"

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    ).

    Bye!

    Crisp
     
  8. Tom2 Registered Senior Member

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    726
    Re: This sounds new to me...

    You know what? I left out a step.

    If one considers only mechanics, then you are exactly right--there is no need for a frame of absolute rest. However, the form of the EM wave equation is not preserved under the GT. What's more, no transformation of the field itself can be done to recover the form (as it can with quantum mechanics).

    If you want to get E+M under the umbrella of Galileo/Newton, you have to enlarge the logical system to include a frame of absolute rest. That frame is the frame in which Maxwell's equations take their textbook form.

    I should have made that clearer before presenting my breakdown of Newton/Galileo.

    Good catch, Crisp.

    Tom
     
  9. James R Just this guy, you know? Staff Member

    Messages:
    34,678
    zanket,

    You said:

    <i>The traveling twin, on the other hand, is moving relative to both the stay-at-home twin and the space between the twins.</i>

    This sounds suspiciously like an ether theory to me.

    Space is not a substance. It is a coordinate system. There is no absolute space that you can measure motion relative to.
     
  10. Prosoothus Registered Senior Member

    Messages:
    1,973
    Tom2,

    Well, regardless of who started, I will refrain myself from making any more personal attacks.

    I'm interested in the answers you have for the following thought experiment. I apologize to James and Crisp since we already had a long debate about this very same experiment.

    Experiment:

    Let's say that you are flying through space in your spaceship at .90c with two flashlights in your hand. You have a clock in your spaceship, and you are flying towards a stationairy clock.

    The moment you fly over the stationairy clock, you turn your clock and the stationairy clock on. Also at the same time, you turn on both of your flashlights: you point one flashlight forward (in the direction of your motion) and you point the other flashlight backwards.

    You continue travelling at .90c while pointing your flashlights in opposite directions for 1 second of the stationairy clock.

    After 1 second of the stationairy clock, the backwards beam of light is 300,000 km away from the stationairy clock, and the forward beam of light is 300,000 km away from the stationairy clock in the staionairy clock's frame of reference.

    Since your spaceship is now 270,000 km away from the stationairy clock in the stationairy clock's frame of reference, the backwards beam of light is 570,000 km away and the forward beam of light is 30,000 km away from your spaceship relative to the stationairy clock's frame of reference. To summarize:

    In the stationairy clock's frame of reference:

    L1=570,000 km
    L2=30,000 km
    t=1 second

    Now since you are travelling at .90c, relativity dictates that you are experiencing time dilation and length contraction relative to the stationairy frame of reference.

    Question: Apply the time dilation and length contraction resulting from your motion to the values given above so that the speed of BOTH of the beams of light in your frame of reference are equal to c.

    Overdoze: I'm interested in your result, as well.

    Tom
     
  11. Chagur .Seeker. Registered Senior Member

    Messages:
    2,235
    Prosoothus ...

    Although I can accept ... No, not take issue with, your use of the
    expression 'stationary clock'; but when you use the expression 'the
    stationairy frame of reference' I've got to ask: What are you talking
    about?

    A 'primary' frame of reference? ... Okaaay.
    A 'stationary' frame of reference? ... Nokay.

    Take care.
     
  12. Prosoothus Registered Senior Member

    Messages:
    1,973
    Chagur,

    Sorry for the confusion.

    When I said "stationairy clock" I meant a clock that is "relatively" motionless, such as a clock on Earth.

    When I said "stationairy frame of reference", I meant the frame of reference of the "stationairy clock".

    I hope this clears things up.

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    Tom
     
  13. Chagur .Seeker. Registered Senior Member

    Messages:
    2,235
    Prosoothus ...

    I suspected as much, but there was the possibility that I had
    missed something while reading through the thread; therefore
    the post.

    Take care.
     
  14. (Q) Encephaloid Martini Valued Senior Member

    Messages:
    20,535
    cest moi

    If you'd have better developed senses, you would perfectly know if you were moving or not, regardless of the other train moving. You might for example feel that the wheels below you aren't turning

    The analogy of the trains, or buses, or cars, or whatever, is commonly used to explain certain aspects of reference frames in a simplified way. It is commonly used because we cannot experience velocities in space. If we could, those analogies would become redundant. It is true that in each example acceleration would be noticed however, once we are moving at a constant velocity, the analogy of not knowing who is moving becomes relevant.

    btw - I don't care how "sensitive" ones senses become, it is highly unlikely one could ever "feel" wheels turning. If one were in a sitting position, would the senses in ones backside be required acuteness to determine wheel rotation ?

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  15. overdoze human Registered Senior Member

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    310
    Awww, shucks. Nice to know someone around here still cares what I think.

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    Sorry I haven't been a more prolific/frequent poster lately. Simply too many things to juggle... Anyway, my analysis is simple. In your particular problem, Lorentz transformations don't even come into play. You can treat it using Newtonian relativity, which has been mentioned by others here.

    Point is, you don't know which frame is "stationary" vs. "moving". For the "stationary" frame, the moving frame is moving. For the "moving" frame, the "stationary" frame is moving while the "moving" frame thinks that it stands still.

    Anyway, as judged by the "moving" frame, its lightfronts are moving out at the same speed both forward and backward. The "stationary" frame is flying backward at 0.9c, so of course it will be closer to the backward lightfront than the forward lightfront.

    As judged by the "stationary" frame, its lightfronts are moving out at the same speed both forward and backward. The "moving" frame is flying forward at 0.9c, so of course it will be closer to the forward lightfront than the backward lightfront.

    Neither of the observers is absolutely right since neither knows absolutely whether he is stationary or not; the only think they know is that they're both at rest. Both observers are right within their own reference frames, as all of their observations and conclusions are internally and mutually consistent. In fact, either observer can easily calculate how the world looks from the point of view of the other observer, and it would be an equally valid and consistent description of the world. Think of it as two distinct perspectives from two distinct observation platforms painting their correct but different views of the same universe.
     
    Last edited: Sep 9, 2002
  16. overdoze human Registered Senior Member

    Messages:
    310
    This has a bunch of problems.

    First of all, it gives the universe a center and further according to your picture puts us square at this center. Why should the universe be so anisotropic? Why should we happen to occupy such a privileged location; what are the odds of that happening in an infinite universe?

    Second, you would have to explain how such a bizarre distribution of galactic velocities would come about naturally.

    Third, this does not explain the cosmic background radiation. Under your model, the CBR would span the entire spectrum (being merely combined emissions from the infinite universe) rather than being concentrated in a narrow microwave band. Under the inflationary model, the CBR is not only explained but its precise wavelength and intensity as a function of the universe's age is predicted.

    Fourth, this does not explain the power spectrum of cosmic matter density. The inflationary model matches this spectrum quite well based on postulated magnification of quantum fluctuations and plasma sound waves during the inflation era. As far as I can tell, there is no explanation of the observed cosmic matter distribution under your model.

    Fifth, distant galaxies might have problems maintaining normal orbital dynamics due to their relativistically amplified momenta.

    Sixth, you'd have trouble explaining the inflationary effect that has been reported lately to actually be accelerating the expansion of the universe (meaning that according to latest data the universe is not flat but in fact open.)

    Finally, if you run such a universe back in time to its inception, you should see that it no longer collapses neatly into a point. Because galaxies 15 billion years away move away from the center at virtually the same speed as galaxies 150 billion years away, that would mean that 15 billion years ago the universe consisted of the Big Bang nucleus surrounded by an infinite expanse of matter speeding away from it at near lightspeed. You get a non-instantaneous, ongoing Big Bang. No such thing is observed, so it must have stopped. How, why, why now?
     
  17. zanket Human Valued Senior Member

    Messages:
    3,777
    Tom2:

    Thanks for responding and for the link to the interesting doc.

    I mean that the distance from the Earth to the galaxy, as measured by us on the Earth, is 3 million light years. But I, in the ship, at the moment I pass by the Earth, measure my ETA to the galaxy at 1 proper year. So doesn’t that guarantee that my proper distance to the galaxy is < 1 light year? Because if my proper distance was >= 1 light year then I’d have to be moving relative to the Earth and the galaxy at > c to reach the galaxy in 1 proper year.

    While I’m flattered given your level of physics, mustn’t it be true that my proper distance to the galaxy increases from < 1 light year to 1.5 million light years during the deceleration? As above, it seems my proper distance before deceleration must be < 1 light year. And after deceleration, when the Earth-me-galaxy system is at rest with respect to each other, with me in the middle, it seems my proper distance must be half of the distance that the Earth measures to the galaxy. Since I measure my proper distance before and after deceleration, it seems acceleration doesn’t muddy the equation, allowing me to simply use special relativity for the before measurement, and just divide by 2 for the after measurement. Can you give some indication as to why it’s not that simple?

    Assuming by “origin” you mean where I’m at when I measure, the former but let me clarify. Some of my books are clear to make a distinction between what you measure locally and what you measure from afar. They point out that you can, for example, measure objects approaching you at >= c due to the time it takes their image to get to you (a “signal transmission delay time effect”). They say the solution is to imagine that you have a team of observers who are all at rest with respect to you (you are all “flying” in formation). The assistant observer who is local to the object measures the relative velocity and sends you the information. Upon receipt of the information you would find that the galaxy was moving relative to you at < c as expected. The galaxy only appears to move relative to you at >= c.

    So I could restate like this: “Although the galaxy is measurably receding from me at far > c, as measured by me from afar, all my assistant observers, who are at rest with respect to me but local to the galaxy, measure their velocity relative to the galaxy at < c, and, this being my true velocity relative to the galaxy, I continue to receive light from the galaxy, although the light is extremely redshifted.”

    I’m only guessing the galaxy’s light would be redshifted as I observe it, simply because it seems too odd to accept otherwise given that, although my assistant observers tell me that I continue to close the gap between myself and the galaxy during my deceleration, I nevertheless measure the galaxy shooting away from me at far > c. If I could see the galaxy (if its light remains in the visible range), I should see it move from taking half my field of vision, to telescopic distance.
     
  18. zanket Human Valued Senior Member

    Messages:
    3,777
    James R:

    No absolute space is required for my statement “The traveling twin, on the other hand, is moving relative to both the stay-at-home twin and the space between the twins” to be true.

    Imagine that the stay-at-home twin is on the Earth, and the Earth has an incredibly tall tower on it, such as the 37,000 km behemoth in Arthur C. Clarke’s book 3001. If the traveling twin moves parallel to this tower, he measures its height contracted. Imagine the tower has altitude markers affixed at every 1 km as measured from the ground. The traveling twin measures < 1 km between the markers. Remove the tower and leave the markers separated by space. He still measures them < 1 km apart. Take away the markers and the space remains contracted.

    When you move relative to matter, not only the matter measures contracted along your axis of motion, but the space between the matter as well, whether that space is between the atoms of a single chunk of matter, or between two widely separated chunks of matter.

    The book Relativity Simply Explained puts it like this (italics are the author’s): “It is true that all motion is relative, but in this case there is one all-important difference between the relative motion of the astronaut and the stay-at-home. The stay-at-home does not move relative to the universe.
     
    Last edited: Sep 9, 2002
  19. Prosoothus Registered Senior Member

    Messages:
    1,973
    Overdoze,

    That's true, but relativity dictates that it doesn't matter which frame of reference is moving and which one isn't. The speed of both beams of light are supposed to be c in BOTH frames of reference. However, when you apply time dilation and length contraction to one beam to make its speed equal c, the same time dilation and length contraction will make the other beam NOT equal c. In fact, there is no value that you can multiply with BOTH beams to make both of their speeds equal c.

    The only solution to this problem is to apply two different time dilations or two different length contractions to the beams. However, this can't be allowed since every frame of reference can have only one time dilation and one length contraction value.

    I asked you this question specifically because even though you claimed that the one-way speed of light can't be measured, it can be mathematically extrapolated by conversions from one frame of reference to another.

    Tom
     
  20. Tom2 Registered Senior Member

    Messages:
    726
    Yes, because those two distance measurements are made from two different reference frames. It is never valid in SR to mix measurements from different frames.

    I'm going to be really busy for the next few days, but I will get back to this as soon as possible.

    Tom
     
  21. c'est moi all is energy and entropy Registered Senior Member

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    583
    yoh (Q) - we could determine the motion be feeling the wheels moving over the ground ... whether we would need this or not is not important

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    you don't care ... but it seems important to me: the theory of relativity is also based on our senses.
    The example of the train is extrapolated into space, no?
    Because it is based on our limitations, the theory can only be but representing half of the truth. by the way, i'm not a positivist ... that should explain my resistance
     
  22. James R Just this guy, you know? Staff Member

    Messages:
    34,678
    zanket,

    I agree with all that, but the last bit needs clarification:

    <i>"It is true that all motion is relative, but in this case there is one all-important difference between the relative motion of the astronaut and the stay-at-home. The stay-at-home does not move relative to the universe.”</i>

    When it says "the universe" here, the statement only makes sense if it is talking literally about all the rest of the matter in the universe. It is <b>not</b> talking about motion relative to some absolutely stationary space, because such a thing doesn't exist.

    Perhaps you mean the matter in the universe too? In that case, I have no problem with what you've said, only how you choose to express it.
     
  23. zanket Human Valued Senior Member

    Messages:
    3,777
    overdoze:

    Nobody would be at a privileged location. Everyone in the universe would measure the recessional velocity of other galaxies as greater, the greater the distance from them. Those recessional velocities would approach but not attain c. It would only appear to everyone that they themselves are at the center, as pictured in this link from Ned Wright’s Cosmology Tutorial:

    Where was the center of the Big Bang?

    Many cosmologists describe the Big Bang as an explosion of spacetime. “My” model would be like an explosion of matter within spacetime. These viewpoints may be equivalent given this link:

    Are galaxies really moving away from us or is space just expanding?

    The CBR in my model would come from that matter which, relative to us and due to its velocity close to c relative to us, has just reached the age of visibility after the Big Bang. Again due this matter’s recessional velocity close to c relative to us, the radiation we detect from it is extremely redshifted, into the microwave band. See also the link in my response below to your 7th point.

    I can’t directly speak to the inflationary model since I’m no expert on it. Cosmic matter distribution seems to be explained by my response above to your 2nd point. Ned Wright’s site doesn’t outright declare that my model (the special relativistic model) is incompatible with the inflationary model.

    The amplified momentum is relative. A space ship might be going .9(billion 9’s)c relative to you, giving the ship a fantastic momentum relative to you, but on the ship everything could be normal.

    A flat universe is an open universe I think. The latest data shows the universe is flat (MAXIMA Finds Flat Universe) but nevertheless accelerating in its expansion, requiring undiscovered “dark energy” to explain this data within the context of a general relativistic universe. So the GR model has trouble explaining the accelerating expansion as well.

    This link nicely explains how the Big Bang was not an explosion from a single point:

    Why haven't the CMBR photons outrun the galaxies in the Big Bang?

    This explanation applies to my model as well, given my response above to your 2nd point.

    I’m really just being a devil’s advocate here. I’m open-minded about other models of the universe, and I’m no expert to boot. My main point is that those who don’t accept or otherwise ignore the reality of the distortion effects may misunderstand the special relativistic model.
     
    Last edited: Sep 10, 2002

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