Time Dialation, Length Contraction.. Reality or Effect?

Discussion in 'Physics & Math' started by Fallen Angel, Jun 13, 2004.

  1. Fallen Angel life in every breath Registered Senior Member

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    I keep on reading posts about time dialation and length contraction, and the more I read the more it seems to me that those are effects caused by our measuring devices and have harder and harder time to buy the whole idea as correctly describing TRUTH.

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    I agree that it is the way we measure things, so our measurements are the only way to find out what happens. But it seems to me that our connection with the universe is limited by our senses, and that it is not as bizzare a place as special relativity makes it out to be. Yes, we cannot get rid of the bizzareness because we have to measure things, and photons are a good way to measure them. But is there a difference between our reality, and the reality of the true universe, not hindered by our limits of measurement?

    Let us go back to analyze the method of measuring time and length. Let's think back to the light clock, where you send out photons to do your time checks and it shows you the EFFECT of zero distance and the EFFECT of instantenous time.

    Remember the classic photon bouncing off of a mirror, and a round trip was one time unit? Well, if you send out a photon in your light clock, but you are moving at the speed of light, and speed of light is same in all referene frames, then you can travel any distance whatsoever and that photon will never catch up to you because you are moving at c. So the first time period never comes until you stop or slow down, so time stops.

    The distance contraction. Remember, your time does not move until you reach your destination as explained in the paragraph above. Then you stop and the photons of the time clock catch up to you and you can count time again. So if you are moving towards a far away place in the universe. (remember velocity = distance / time). You send out a photon to the destination. But you are moving at the speed of light, so you are chasing that photon all the way to the destination. And at the same time the time photon is trying to catch up to you. Once you arrive at the destination, the photon bounces off of it and reaches you. You check your time to see how long it took to get to the destination and the first photon of your light clock just now catches up to you, so you conlude that the distance is zero because light speed is constant and you sent out the photon and got it back immediately.

    So it feels like the distance is zero, and it feels like the time stopped. But does space really contract to meet you? Does time really slow down? Or are you just chasing photons, and your time photons are chasing you??
     
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  3. pmb Banned Banned

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    So forget about truth. Focus only on what is measured. Nothing else matters or is meaningless in physics.

    How would you propose to test the difference?
    Sorry but I don't understand the above comment. Can you clarify please?
    It doesn;t have to be. In fact in all derivations that I've done and seen do not assume that. E.g. this is a good example of such a derivation
    http://www.geocities.com/physics_world/sr/light_clock.htm
    The light clock can never move at the speed of light. It's only the light that is moving at c in that derivation.

    Since "I" can never move at the speed of light, that comment is meaningless.

    For a derivation of contraction see
    http://www.geocities.com/physics_world/sr/lorentz_contraction.htm
    In that derivation you'll notice that the rod does not move at c but at v<c.

    Pete
     
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  5. Fallen Angel life in every breath Registered Senior Member

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    Ahh.. excellent pmb, I was looking for those diagrams to clarify what I was talking about. And sorry about the restriction in my argument about moving at c. I copied and pasted from another thread I put this in and decided that I should ask it here separately, forgot to correct that little bit. I still stand by my argument for velocities less than c. Instead of no photons reaching you, fewer photons reach you, etc. etc.. the moving at c part is just to clarify my reasoning, but it still applies to v < c.

    And the comment with all the "EFFECT" stuff capitalized was just pointing out my struggle with reality and what is measured. And I hear you on the comment to focus on what is measured and that being the only real physics. However, that approach may perhaps be limiting in our view of the world. If we look only through our limitations of measurement, we may not be seeing the forest for the trees. After all, light is measured to be c in all reference frames. Yet a guy traveling sees space contract in direction of travel, time slows down relative to others. All of those effects, and I say effects, because space cannot actually contract (i can buy the bending, because mass is there to bend it, but contraction because of traveling through?), just to keep light speed constant. There has to be something else there. A person stationary relative to the traveler will not see space contraction. The other individual is not entering a new universe, that person is simply experiencing an effect. How do I test this? Give me some time to think on it

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  7. Quantum Quack Life's a tease... Valued Senior Member

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    correct me If I am wrong but if an object is time dilated then distance is covered more quickly in a relativistic sense, therefore space is not actually contracting but the distance becomes less to the time dilated object.

    1 second of travel becomes 2 seconds of travel whilst appearing to remain as 1 second of travel.....type thing.....so space it self is not so much the issue but the time experienced by our object is.
     
  8. Fallen Angel life in every breath Registered Senior Member

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    yes indeed... i agree with you. at the same time, that time dialation turns into a measured space contraction. since time goes slower, if you measure a distance in your direction of motion, between you and a destination for example, then it will appear to contract because the photons that measure that distance will get to you faster because.. time is slower (yet photons still move at c relative to everyone). distance = velocity * time. velocity here is c of the photon you send out to measure the distance between you and destination. since time is slower.... distance covered will be less... and you're traveling towards the photon, which further shrinks the distance. So physically we can argue that space contracts in the direction of travel and time dialation happens because we can measure both. But does it really happen? Or is it the effect of the measurement in our frame? That is my point on the difference between effect and reality/truth/whateveritsnameis

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  9. Janus58 Valued Senior Member

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    You said to correct you if you were wrong, so I'm doing so.

    It's not just a matter of the time it takes for the object to reach a distance.

    For instance, if a ship were traveling along a tape measure marked off at 1 meter intervals at .866 c relative to the tape measure and he were to place a meter stick of his own parallel with it, he would see that two of the meters on the tape measure would fit inside the length of his meter stick.

    Or you can imagine two measuring tapes; one extending from the Earth and the other from a ship. As the occupant of the ship passes the 100,000,000 km mark on the Earth's tape, he will note the the Earth is only passing the 50,000,000 km mark on his tape.
     
  10. Quantum Quack Life's a tease... Valued Senior Member

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    we often talk about length contraction but what about width contraction?
    How does velocity effect width?
     
  11. Janus58 Valued Senior Member

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    Contraction only occurs along the axis of relative motion.
     
  12. Quantum Quack Life's a tease... Valued Senior Member

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    thanks Janus58, this obviously leads to the next question....
    How is space immediately to the right and left of this axis effected by this contraction?

    If space is contracted are we only talking about 1 dimensional space or 4 dimensional space?
     
  13. Pete It's not rocket surgery Registered Senior Member

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    It's contracted in parallel.

    3D space is contracted in 1 dimension.

    4D spacetime is essentially unaffected, but its division into space and time is different.
     
  14. Quantum Quack Life's a tease... Valued Senior Member

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    so what happens do you think if our object changes direction, say 2 degrees to the left every Ly until it eventually ends up back where it started?

    how is space contracted for anything other than a straight line?
     
  15. Fallen Angel life in every breath Registered Senior Member

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    I don't think that the actual space is contracted. Because anyone seeing (with photons) the spaceship, will not see space around it contracted at all. Just the spaceship itself. I think the issue is our simultaneity of the measurement. It differs between a stationary frame and a moving frame, so the measurements of length will differ. That does not make sense to me (the interpretation that physically, the space contracts because we are moving through it). I put an argument against it in my model for confirming / denying time dialation. It addresses the issue of simultaneity and space contraction and time dialation as an effect of measurement using light, not as what actually happens. (what actually happens can be measured using my setup using the quantum entangled clock)
     
  16. Janus58 Valued Senior Member

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    Then from the ship, the circle it travels has a smaller circumference than it does for the observer at the sarting point. But then also the ship is no longer in an inertial frame of reference because it is under acceleration.
     
  17. MacM Registered Senior Member

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    Question: HOw does the EM wave front associated with velocity enter into your answer, if it does?

    That is when an object contracts to a length of "zero" in the direction of motion at v = c, it also has an EM wave front that is infinitely wide and high.
     
  18. geistkiesel Valued Senior Member

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    Suppose you have three rapidly spinning disks oriented with axes at 90 degrees to each other. One axis is pointed along the moving frame's direction of motion. As this disk is spinning transverse to the direction of motion and the other two disks are rotating with their spins proportional to sin(thetat) (the angle of the disks with respect to a fixed point in the frame giving peiodic +v and -v), does not SR theory predict the frame with spinning axis parallel mto the motion of the frame will be unaffected by the motion of the frame (assuming the disks are in afree state of rotation) and the other two disks will slow down at a faster rate?
     
  19. Pete It's not rocket surgery Registered Senior Member

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    No. The three disks will slow down at the same rate, all other factors being equal.
     
  20. Brandon9000 Registered Senior Member

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    Since your argument, if correct, will prove that elements of Special Relativity are incorrect, may I ask if you plan to publish in an actual scientific journal? Since scientists all over the world have been scrutinizing Special Relativity for a century, and have found nothing incorrect about it, such a revision would be a major worldwide scientific event, and should be made available to the scientific community.
     
  21. Fallen Angel life in every breath Registered Senior Member

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    . Yeah yeah, I know. Well, it doesn't make sense to me because of the light measurement of length contraction. What I originally understood length contraction to be the effect of was a result of measurement of lenght using light. Essentially, it said that if I try to measure a distance, I can roll a ball towards the object, and then run towards the ball, and when it bounces back I'd be much closer to the object. And since I moved towards it, then the distance from my original place is contracted. Well, no, I just ran towards the stupid ball. Hence my misgivings about length contraction, because that measurement sounds hokie to me. But James R pointed out that contraction and dialation are a result of something else or rather that they can be aquired independently of using light as the measurement, so I'm spending my time looking at that. Well, actually he talked about simultaneity, but yeah, light independent incapability of synchronizing clocks over different inertial reference frames. Something about Lorentz transformations. But you can take a look at my thought experiment to perhaps understand the nature of my doubts, whether founded or not. http://www.sciforums.com/showthread.php?t=37406
     

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