On Einstein's explanation of the invariance of c

Discussion in 'Pseudoscience Archive' started by RJBeery, Dec 8, 2010.

  1. Motor Daddy Valued Senior Member

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    You must be talking about the velocity of light, which means it takes light one second to travel ~186,000 miles, in each direction in THE frame.
     
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  3. Tach Banned Banned

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    No, I am talking about the TIME is takes the light to travel E->W vs. W->E as viewed from a frame moving at speed v wrt your "volume universe frame". You seem to have a lot of difficulty grasping the concept.
     
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  5. Motor Daddy Valued Senior Member

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    If you are asking me how much time it takes light to traverse an object in each direction, my answer is that you need to MEASURE the one-way light travel time. How else would you know how much time it takes for light to get from point a to point b, and vise versa???
     
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  7. AlexG Like nailing Jello to a tree Valued Senior Member

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    I don't think anyone here agrees with you. You insist that there is an absolute inertial frame, and base your entire argument on that assumption. You then use your assumption to try to prove itself.

    You're wrong.
     
  8. Motor Daddy Valued Senior Member

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    Really?? So you've defined distance to be inseparable from elapsed time of light travel.

    Question: If I measure one-way light travel from one end of an object to the other, and then check it the other way, and the times are different, what is the length of the object? Surely you understand the time of light travel is how far the light traveled, and not necessarily the length of the object?? You do realize objects can have motion, correct?? In motion relative to what? Another object's motion? Sounds circular to me, as light travel defines distance.
     
    Last edited: Dec 20, 2010
  9. Tach Banned Banned

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    The object proper length is D. You are looking at it from a frame moving at v moving in the direction E-W..
    How much time it takes light to traverse it from E-W?
    How much time it takes light to traverse it W-E?
     
  10. Motor Daddy Valued Senior Member

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    You solve for D by measuring the one-way light travel times. There is no other way of solving for D, unless of course you know your own length and velocity, which brings me back to my point.

    By not knowing your own length and velocity you have a circular argument, as is Einstein's.

    BTW, you don't calculate one-way times, you MEASURE them!
     
    Last edited: Dec 20, 2010
  11. Tach Banned Banned

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    So, you have no clue how to solve this simple problem.

    False, if you knew relativity you would have known how to calculate the transit times. Since you don't, you can't.
     
  12. Motor Daddy Valued Senior Member

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    Tach, Do you believe that light always takes 1⁄299,792,458 of a second to travel from one end of a meter stick to the other, or for that matter, does it always take light double that time to travel a meter stick round trip??
     
  13. Tach Banned Banned

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    Yes. This should not preclude you in doing the calculations I have asked you to do.
     
  14. Motor Daddy Valued Senior Member

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    Do you believe the meter stick can be in motion?
     
  15. Neddy Bate Valued Senior Member

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    Motor Daddy, you are the one who does not believe the above is true. You only think that is true when the meter stick is at absolute rest.

    According to your fictional universe, if the meter stick is not at absolute rest, then the light takes some other mount of time to travel the meter stick. Relativity theory says that light takes 1⁄299,792,458 of a second to travel from one end of a meter stick to the other, even without the concept of absolute rest. You'd have to understand the Lorentz transforms to understand how that can be possible. I have a feeling you'd rather stay in your own fictional universe, rather than learn to understand the Lorentz transforms. But if you'd like to learn them, just ask. I'm sure someone here would be willing to help you.
     
  16. Motor Daddy Valued Senior Member

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    You're correct, I am the only one who understands the concept of light traveling independently of objects (such as a meter stick), hence I am the only one who has ever been able to measure the velocity of a box in space from within the box.

    Tach does not understand how light travels, as evident by him saying light always takes the same amount of time to traverse a meter stick, regardless of its motion. That is absurd! That is like saying it always takes you 10 seconds to pass a school bus when you are doing 60 MPH. Absolutely absurd!
     
  17. Tach Banned Banned

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    You should stop stalling and you should answer the question. It is a very basic one, if you don't know , just admit that you don't.
     
  18. Motor Daddy Valued Senior Member

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    Which question? Can you explain to me why you think light always takes the same amount of time to traverse a meter stick, regardless of its motion?
     
  19. Tach Banned Banned

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    The Nobel committee has been duly notified. You are at the head of the list.

    Err, no. I have been asking you to figure the transit time from the perspective of two different frames. You are obviously unable to do so.
     
  20. Neddy Bate Valued Senior Member

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    Then why do you often refer to the meter being defined by light speed? Don't you realize that definition applies to all sorts of reference frames which are not at absolute rest? For example, on the surface of the earth?

    A better analogy would be to say that your definition of a meter stick still holds true in a car doing 60 MPH. I can understand why you'd think it absurd, but there are simultaneity issues, and other issues that make sure it does not lead to any contradictions.
     
  21. Motor Daddy Valued Senior Member

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    Light travels a specific distance in space in a specific duration of time. It always traverses space the same distance in the same time. That makes it a constant, so we can use it as a standard to measure the distance light travels by measuring the time of travel. We defined a meter to be the distance LIGHT travels in 1⁄299,792,458 of a second. So we know that if light is sent from one end of the meter stick and it arrives at the other end of the meter stick in 1⁄299,792,458 of a second, the meter stick has an absolute zero velocity. If the light is sent from one end and arrives at the other end in .5 seconds, the light traveled 149,896,229 meters, and the stick traveled 149,896,228 meters.

    Do you understand that concept??
     
  22. Neddy Bate Valued Senior Member

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    2,548
    I can. Remember when RJBeery asked you to measure the width of the continent using light signals? These were your steps:

    1. Synchronize the clocks at each coast by pulling strings from the center of the continent

    2. Measure the one-way travel times for light in both directions

    3. Calculate the absolute speed of the country

    4. Calculate the width of the country.



    Well, in relativity, they do things a little differently than that. It goes something like this:

    A. Synchronize the clocks at each coast by sending light signals back and forth between the clocks

    B. Measure either the round-trip or one-way travel times for light

    C. Calculate the width of the country.

    You see, "A" causes the one-way travel times of light to always be the same in either direction. That is why "B" can use either the round-trip times. or the one-way times. And then "C" lets you can calculate the width of the country without knowing its speed. It's not that different from your method, except there is no such thing as absolute simultaneity, and there is no such thing as absolute speed. With this method, the light-based definition of a meter holds true in all inertial reference frames.
     
  23. Neddy Bate Valued Senior Member

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    Yes, I understand. You took the existing definition of a meter, and added your own stipulation that it only holds true in the absolute rest frame. There is no such stipulation in the real definition of a meter.
     

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