# anything and everything can and is moving faster than c

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#### SpeedFreek

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Ok, so there are 3 ships travelling in line at 90% of c, each 1 light minute apart... the rear ship has a reflector on the front, the middle ship has lights front and rear and the front ship has a reflector on the back... <img src="/images/icons/wink.gif" /> <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

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#### larper

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Ok, so the middle ship shines a yellow light at both of the other ships. Those ships see a yellow light, and reflect a yellow light. The middle ship sees two yellow lights reflected. <br /><br />Meanwhile, an outside observer sees the middle ship emit a blue light out the front and a red light out the back. He sees the forward ship shine back a red light, and the trailing ship shine back a blue light.<br /><br />All observers agreed that the light is traveling at exactly c. Photons gain and lose energy, but they don't gain and lose velocity. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

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#### SpeedFreek

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So if the 3 ships are 1 light minute apart and moving at 90% of c, can I put some <i>timings</i> to the example?<br /><br />On the middle ship, both lights should return in 2 minutes. The end ships each see the yellow light take 1 minute to reach them and 1 minute to return to the middle ship (as <b>all</b> ships can consider themselves at rest?)<br /><br />To the observer, the front light is moving only 10% of c faster than the 3 ships themselves, and the front ship stays a constant distance of 1 light minute in front of the middle ship. So does the front light take 10 minutes to reach the front ship?<br /><br />Conversely, should the rear light cross the distance to the ship at the back in 6 seconds (if the light moves at c, and the ship at the back is moving towards that light at 90% of c from the observers frame of reference?)<br /><br />After reflection, does the front light return to the middle ship in 6 seconds, and the rear light take 10 minutes to return to the middle ship?<br /><br />Is this why different observers cannot agree on the simultaneity of events? Or does the time dilation on the ships account for the difference in timings? <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

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#### larper

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That is pretty much correct. The outside observer sees the lights taking different times to travel back and forth, and these times are different than an observer on the ship. So, to "us", 10 minutes is like 2 minutes to someone inside the ship. Ergo, time dilation. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

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#### SpeedFreek

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And yet, if we imagine that all 3 ships emit a light towards the outside observer, whenever they send or receive the light from the other ships...? (They are moving perpendicular to the observer, so all lights take the same time to reach that observer)<br /><br />Then obviously, in the ships, nothing changes. The middle ship emits both lights at the same time and emits a light towards the observer, the end ships receive those lights 1 minute later and bounce them back, emitting lights towards the observer at the same time. The middle ship receives both lights back again after 2 minutes and emits another light towards the observer (if they happened to arrive at different times it would have emitted 2 lights, but that doesn't happen!)<br /><br />Now to the observer, they receive the first light from the middle ship as it emitted its lights fore and aft. Then, only 6 seconds later, it receives the light from the rear ship (when the aft light was bounced). 10 minutes later the observer sees the light from the front ship (emitted when the fore light was bounced). 6 seconds after that, it receives the final light from the middle ship when both bounced lights arrive back simultaneously.<br /><br />So when both lights return to the middle ship simultaneously, the symmetry of the process is intact, and the maths all works out. But can time-dilation on the ship explain what the observer sees?<br /><br />Let's back up a bit, to where the lights from the middle ship first reach the front and rear ships. To the observer the rear ship gets the light 6 seconds after emission, and the front ship gets the light after 10 minutes. Is <i>that</i> where we observe a difference in simultaneity which cannot be attributed to either time-dilation or light travel time? If the observer sees such a huge difference in the times that the front and rear ships bounce those lights back, how can the middle ship account for that difference with time-dilation? Surely time-dilation will affect that middle ship <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

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#### vandivx

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"Question it all you want, but it is indeed how the universe works."<br />---<br /><br />you seem to be sold on the view that I am disputing results of SR which is totally contrary to what I posted<br /><br />I repeat all observers always measure speed of light to be constant c, period, that's what I believe to be the case, SR is right on this point, what I dispute is that length contraction and time dilation effects are valid explanations for what is measured<br /><br />all I am saying is that the length contraction (as in physical contraction of objects along the direction of motion) can't be used to explain why any party to experiment measures the speed of light to be c because explanation based on this assumption doesn't hold in the case I dispute here, it either has to work in all cases or its wrong to use it to explain what somebody measures (I repeat everybody measures speed of light to be c which is how reality works, I have no problem with that whatsover)<br /><br />I am not really surprised that you are missing the point and that all physicists out there are blind to it because if it weren't so very likely physics would today be much farther than it is and it is not any further in this area then when Einstein left it some hundred years back, sorry state of science if you ask me<br /><br /> " ... The box has two doors... "<br />---<br /><br />why don't you refer directly to THE famous 'pole and barn paradox' as it is widely known and save yourself some words, everybody knows about that one who is familiar with SR even as an amateur, it is called paradox because there is pretty serious disagreement over it, same as over 'twin paradox' but I wouldn't pull those in here because it would just kill the thread and take us off the track and the simple point I was trying to make would soon be forgotten<br /><br />vanDivX <div class="Discussion_UserSignature"> </div>

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#### vandivx

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<blockquote><font class="small">In reply to:</font><hr /><p>"yes the ship can consider itself at rest but what we are talking about here is what you see when you look at the ship as outside observer and see it moving near the speed of light"<br /><br />But we dealt with what the outside observer would see earlier on. The problem we had was reconciling their view with the view from the ship.<br /><br />Remember, if the ship were travelling at 90% of c, we would as an outside observer see the light moving away in front at c (10% of c faster than the ship) and light moving away behind from the point of emission at c, with the ship moving away from the point of emmission at 90% of c, and therefore moving away from the emitted rear light at 190% of c.<br /><br />The problem occurred when trying to explain these numbers from the view inside the ship, if the ship sees its fore and aft light both moving away at c.<p><hr /></p></p></blockquote><br /><br />I quoted the whole thing including you quoting me in it because you got it wrong, just sit on it<br /><br />read your last sentence in that quote, 'from the view inside the ship' everything works out fine no problem, the rocket guy doesn't know nothing about his ruler changing length and he does measure the speed to be c in all directions, there is no problem there, change in ruler length and time slowing down is seen only by the outside observer and ALL I am saying is that it doesn't explain where the aft light beam speed measurement is concerned as seen from the outside because from outside you would have to see the ruler expanding and time speeding up (to explain to yourself the rocket guy's measurement results for aft light beam) and SR knows nothing about such things happening - rulers only contract, not dilate and time only dilates, that is slows down, it never speeds up, that has been canonical view of SR for hundred years and I am challenging that such physical effects are valid for explaining what is actually measured (speed c in all re <div class="Discussion_UserSignature"> </div>

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#### origin

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Origin said:<br />--------------------------------------------------------------------------------<br />If I am in a Jet traveling at 330 m/s and I have a multi directional speaker send out a sound, the sound will move along direction of travel at ~10 m/s and behind me it will recede at ~670 m/s relative to the jet. <br />--------------------------------------------------------------------------------<br /><br /><br />Larper replied:<br />--------------------------------------------------------------------------------<br />No, it won't.<br />--------------------------------------------------------------------------------<br /><br />Really. What speed do you think the sound will travel? I hope you are not quibbling about air density and exact speeds down to the mile/hour. The concept is correct. <br />Please explain why you think what I said was incorrect. The sound waves (with the source at < supersonic speeeds) will travel out at the speed of sound independant of the movement of the source. <div class="Discussion_UserSignature"> </div>

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#### larper

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I think I misread your post. I thought you were saying that the speed of sound would be different in the two directions.<br /><br />The speed of sound will be constant. But the frequencies will be different. <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

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#### larper

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<blockquote><font class="small">In reply to:</font><hr /><p>it is called paradox because there is pretty serious disagreement over it, same as over 'twin paradox'<p><hr /></p></p></blockquote><br />There is absolutely no disagreement over these "paradoxes". <div class="Discussion_UserSignature"> <p><strong><font color="#ff0000">Vote </font><font color="#3366ff">Libertarian</font></strong></p> </div>

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#### SpeedFreek

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<font color="yellow">read your last sentence in that quote</font><br /><br />Sorry, you are right, I meant to say the problem occurs when trying to explain these numbers from the view <i>outside</i> the ship. Well caught there.<br /><br />I hope you can see, from my later post here, that I do understand the problem you are having. <div class="Discussion_UserSignature"> <p><font color="#ff0000">_______________________________________________<br /></font><font size="2"><em>SpeedFreek</em></font> </p> </div>

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#### olivebird111

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i think..<br />E.....A..................<br />E is earth, spaceship A traveling at 0.999999c, B is the ball<br />E.......AB.............<br />E.......A.B....<br />E..........BA....<br />E.............A...<br />B cannot keep at a constant 1.00000001c, and it is a really bad mistake because B didnt start at the same spot as E, AND, B is propelled of an outside force, the energy of A perpeller and the throwing speed that propelled it. Analogy<br />1 person race around the track, you throw a ball, its faster than you but it stops, its faster because youre using the wrong reference point, if you think about it, its moving at the same speed as you, and you add a little more speed.<br />so technically you can fire 10000 rockets at like 1000m/s<br />and you WILL get 1.000001c..thats because youre not treating the problem correctly lol.

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#### vandivx

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"I hope you can see, from my later post here, that I do understand the problem you are having."<br />--<br /><br />yes I thought it was just a slip, happens to anybody and only prevention is to be on your toes all the time <img src="/images/icons/smile.gif" /> so to speak because these are treacherous grounds that trap unawares by their seeming simplicity (re-reading your post after you posted it also helps and re-reading it next day once more is recommended, that's what I do and I edit my posts for grammar or clarity or even logical slips that way as I do right now plus adding to the post too especially when nobody quoted or replied to me yet), that's also reason why I like to analyze this in as simple way as possible because it is so easy to get lost in complicated graphs of spacetime and equations even if one can follow them<br /><br />and you see also that its not common thing that everybody sees it or more exactly they don't want to see it and nobody is more blind than those who refuse to look<br />initially I thought that just a brief hint would send everybody who looked at this thread scurrying either with explanation or trodding me into ground deservedly or undeservedly but more than a hint was needed as it turned out, I had to spell it out and even then things stayed fairly quiet which likely is because most experts around these forums are from astronomy side of sciences and most of us who tackle physics subjects are not pros (and those who are perhaps don't see that this subject deserves their attention for whatever reason)<br /><br />I think early interpretation of SR was that length and time are changing which was then changed to space itself changing and as consequence the objects in that space were changing (rulers and clocks) but perhaps somebody with more historical knowledge and overview can tell us how it was and what is the situation these days, that is what is the broad mainstream academic view of these things on this subject today<br /><br />thing is that <div class="Discussion_UserSignature"> </div>

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