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Why are the effects of Time Dilation permanent but Length Contraction is Not? 
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#55
Dec2411, 07:27 PM

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#56
Dec2411, 11:30 PM

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Hi DelSpam,
You think the contraction is a physical effect on the space ship and the space ship is being reduced to very near zero length. I think it is a visual effect that we see zero length with no physical effect on the space ship. Meaning it remains the same physical length or slightly larger in the very near "C" ship as it is in the resting frame ship. Do I have that correct? Hi Janus, Earth frame observer is watching a space ship made of glass traveling 0.9C. There is a stationary (same as the Earth frame) photon emitter that will emit a photon parallel to the glass ship forward and backward as the ship passes going 0.9C. There is also one inside the glass space ship that will emit a photon forward and backward. When the space ship lines up with the observer and the outside photon emitter they go off in unison. The Earth observer sees the outside photon emitter’s photons departing from each other at 2C or each at C in opposite directions. Now inside the ship the Earths observer, observes the forward emitters photon going the speed of light (relative ship frame= 0.1C=C). He sees the rear emitters photon going 0.8C forward (relative ships frame 0.1C=C backwards). So to the Earths observer the photons are both going forward at "C" and 0.8C respectively. Do we give up light is measured to be invariant in every frame or give up the idea that the speed of light is the same in every direction within a frame? They are mutually incompatible statements for a photon. Happy Holidays 


#57
Dec2511, 12:42 AM

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For the Observer on the ship, both sets of photons reach the ends of the ship simultaneously. That is what light speed being invariant and the speed of light being the same in every direction in every frame means. They are not incompatible. 


#58
Dec2511, 08:36 AM

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Hi Janus,
If you are suggesting it’s because of the limit of not being able to measure the one way speed of light that I would understand. The round trip is the same for each I agree. If it is a different reality I would like to know the reason. (Unless it is just your understanding of a postulate). If there is a physical explanation please in that case I would be very appreciative. If there is no explanation than we must conclude that the one way speed of light is not measured to be the same in all frames. 


#59
Dec2511, 12:50 PM

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If you now ask them all to point left, they will all point in different directions, as left is defined by the direction they are facing. If you ask them the leftright distance between the two objects, they will give different answers. Some will even say that object one is to the left of object two while other will say that it is the other way around. This is an example of frame dependence. the measurements do depend on how the people face with respect to each other. What Relativity says is that measurements of space and time are more akin to the second example. In Relativity, there is something akin to the straight line distance between the two objects in the example. This is frame independent. Everyone agrees to this even though they might not agree as to the LeftRight and FrontBack components of this distance. In Relativity, it is called the spacetime interval and represents the separation of event in space and time. This interval is something everyone will agree on. What different frames will disagree upon (such as in your spaceship example) How much of the separation is in time and how much is in space. One way to look at it is that we measure time and space we are only measuring "slices" of a larger reality, and that different frames are looking at different slices. 


#60
Dec2511, 01:07 PM

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It is not, however, a visual effect. There are several relativistic visual effects, such as relativistic abberation, relativistic Doppler shift, and TerrellPenrose rotation. Length contraction is what is measured after properly accounting for these visual effects in a given frame. It is not what is seen visually nor with a high speed camera. I would again recommend that you work out the two calculations I suggested above. I think that you will find it educational. 


#61
Dec2511, 02:13 PM

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#62
Dec2511, 03:48 PM

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#63
Dec2511, 09:02 PM

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Hi DaleSpam,
Math is no guarantee that you are correct. While the math does contract the visual object the same as your view. You actually believe the contraction is physical. Does the math prove it’s physical? 


#64
Dec2511, 10:22 PM

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In any case, my repeated suggestions that you do the math are not for the purpose of proving my point, they are simply to help you learn. If I were only interested in proving my point then I would do the math myself. But you will learn more and faster if you do it. 


#65
Dec2611, 12:16 AM

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The first postulate is the laws of physics are always the same no matter the observer, as long as they're inertial. Consider that time is merely a measurement, like length is a measurement. Your intuition is right, just gotta tune it a bit more physicsy. It would be absurd for someone right next to (inertial with) the experiment to believe the photons didn't hit simultaneously. (im assuming this is the scenario) That observer is in the "same" spacetime, specifically frame of reference as the experiment. Said differently, considering another observers FoR doesn't make it "reality". Only your own observation does. I think causality is the final nail in that. In another, more crude way, conscious observers are special in that we can invision what would happen in the other FoR. That cannot "physically" be considered a/the "reality". I know nothing of LET but this conscious observer reasoning would be getting off on the wrong foot (with either theory). I couldn't think of an equation for that. 


#66
Dec2611, 06:25 AM

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#67
Dec2611, 07:10 AM

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The age is like a position, not like length interval. 


#68
Dec2611, 09:21 AM

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Hi nitsuj,
The MMX experiments were not flawed just the math used for the one way distance of traversed light that was assumed. If you took either clock back to their origin they would be synchronized again. 


#69
Dec2611, 12:19 PM

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Qzit, pleas learn to use paragraphs to separate your thoughts. A little bit of organization will help communication a great deal.
I would like to remind you that this forum is not for antirelativity rants, it is for learning mainstream physics. When you signed up for your account you agreed to the rules that prohibit overly speculative posts. If you have an antirelativity agenda you had best look elsewhere. 


#70
Dec2611, 12:22 PM

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Hi DaleSpam,
You and I agree on Relativity being correct but we disagree on what that means. In order to stop getting confused let’s look at everything from the photons perspective. Where do you disagree? 1. The photons minimum and maximum speed are the same in every frame and that = invariant speed of light. 2. Our visual perspective depends on where we observe an object. 3. The photon perspective is the only reality of its own position in space. If we can agree on that we made progress. Now before you read with a challenging attitude try and follow your logic with the three things we agree on not where we disagree. You are riding a photon and you can know the exact position of another photon instantaneously. This removes relativity of simultaneity. Lets go through this thought experiment again because the math is different from the reality of the photon. A space ship is traveling ½ the speed of light. Two photons side by side are traveling an intersect course with the space ship. When the two photons reach the front of the space ship one reflects back to an observer at rest in line with the traveling photons and the ship. The second photon reaches the back of the space ship and reflects back to the same observer at rest. While the photon was moving from the front to the back the ship moved ½ the speed of light forward intersecting a contracted position relative to the length of the ship. We visualize the photon covering 75% and the ship 25%. This is a contraction of the returned photons measurement from the front to the back that the observer at rest sees. (1v^2/C^2)=125=75 just what the observer at rest sees for the returned photon distance. Now because we think light travels the same speed relative to the ships frame we take the square root and get a contraction of 0.866 just about half + the time dilation increase of the ships length by gamma. Once again the MMX experiments are affecting reality of position. The MMX experiment was not wrong but the conclusions of the experiment were incorrect. The Earth frame is the only place you can measure the one way speed of light in a space ship. The returned light from the front and back of the ship will be the same and if you incorrectly divide that by 1/2 you are mistaken when the photon actually hit the back and front of the ship. 


#71
Dec2611, 12:55 PM

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Do you have any mainstream scientific references to support your interpretation?
http://www.physicsforums.com/showthread.php?t=511170 And even if it did no reference frame represents the "only reality" of anything. Your claim that one inertial frame is more valid than another is a direct contradiction of the principle of relativity. 


#72
Dec2611, 01:20 PM

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For demonstration here is the classic train example for the Relativity of Simultaneity. First, events according to the embankment frame: Here the lightning flashes originate when the ends of the train are adjacent to the red dots on the embankment and the embankment observer is at the midpoint between the two. The embankment observer sees both flashes at the same time, and being halfway between the lightning strikes concludes that they occurred at the same time. Notice how the flashes reach the train observer at different times. Now the thing to keep in mind is that in this frame, the train is length contracted, and it it this length contraction that allows it to just fit in between the two dots on the embankment. Now the same scenario according to the Train frame. In this frame, the train is its proper length and it is the embankment which is length contracted. Now the train is longer than the distance between the two dots. The front of the train hits the right red dot before the rear reaches the left dot. The lightning strikes must originate when the ends of the trains are aligned with the dots, otherwise you will have a contradiction between the frames. This means that in a very real sense, the lightning strikes occur at different times in the train frame. If the light from those flashes expand outward at c relative to the train, the train observer will see each flash at different times (just as he did according to the embankment frame. ). The reverse argument is that since he sees the flashes at different times, is halfway between the ends of the train(where the lightning strikes occurred) and the light from the strikes approaches him at the same speed from both ends (the speed of light is invariant), then the lightning strikes occurred at different times. You will also note that in the train frame, the flashes also reach the embankment observer at the same time. Further, if you compare the two animations, you will note that the train observers position with respect to the embankment when each flash reaches him is the same in both as is the embankment observer's position with respect to the train when the flashes reach him. Thus there are no true contradictions between the frames, only a disagreement as to what is simultaneous when it come to events that are separated by some distance. Note that this is not just a matter of one observer being further from the source and seeing it later, because each observer accounts for his distance from the source to determine when the flash really occurred. It is a very real difference in the simultaneity of events separated by distance. This is length contraction and the Relativity of Simultaneity working together. If you were to place clocks at the red dots, the ends of the trains and with each observer (with the clocks in each frame synchronized in that frame), you could include time dilation into the mix, and find that everyone will agree as to what times were on any two clocks when those clocks passed each other, or when the light from either strike hit them. They will not agree as to the synchronization of clocks between frames (each frame claiming their own clocks as being in sync while the other frame's clocks are not), nor as to the relative clock rate between frames. (each will consider the clocks in the other frame as running slow.) This is what Special Relativity is about, there are real differences in time and space between inertial frames. 


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