The purpose of this thread is to discuss whether length contraction is a required conclusion if the speed of light is the same in all non-accelerating reference frames. Here is a simple device that emits two flashes, one to the North and one to the East. The flashes bounce off mirrors that are each one metre away from the device, then return to the device. If the flashes return at the same time, the device pops up a flag to indicate the fact: Please Register or Log in to view the hidden image! Here is the same situation in a reference frame in which the device is moving rapidly Northward. EDIT - ie the device hasn't changed its motion, but our viewpoint (the "camera") is different. This time, we're moving rapidly southward. Thanks Cangas. I've shown it twice... in the second image, I've hidden the device for clarity, showing only the flashes, along with their paths and some key points. These diagrams are not drawn to scale. <table width=100%><tr><td width=50% align=center>Please Register or Log in to view the hidden image!</td><td align=center width=50%>Please Register or Log in to view the hidden image!</td></tr></table> Take Note - in all animations, the device is securely attached to the Earth. In the diagrams in which the device appears to be moving, our viewpoint (the camera) is moving South relative to the Earth and the device. Consider the frame in which the device is moving. If the light flashes are moving at a steady speed, what does that tell us about the distances W and N from the device to the mirrors? (Its also interesting to think about what this tells us about simultaneity, but one thing at a time.)
Pete, For clarity and courtesy I don't think I will debate the issue in your thread but I will start my own thread showing how and why length contraction conclusions are invalid. I will refer readers to your thread to see the SRT arguement.
Just my two cents... The fact that Mac refers to this as a debate gives away his agenda. Given the observed constancy of 'c' in all frames, this is a matter of demonstrable logic, not debate.
Well, if you've got an agenda to push, go ahead. This thread is for open investigation into the logical conclusions of a postulate. I invite you to participate, but you're welcome not to if you so wish.
Thanks for showing you don't have a clue. The fact is my arguement does not challenge an invariant 'c' and is also based on demonstable logic. So there. Please Register or Log in to view the hidden image!
Funny how trying to get people to understand the reality is an agenda and to repeatedly post threads arguing the SRT view is not an agenda. Hmmm.
I am clueless and glueless. Whatever you say, bounces off of me and sticks to you! Ha! Please Register or Log in to view the hidden image!
Has anyone argued the SRT view in this thread? Again... this thread is about open logical investigation. No agendas.
Cool animations Pete! One thing that I have been thinking about is that if you start with the perpendicular clock you wind up with the Lorentz transform, and if you start with the parallel clock you wind up with the Voigt transform (http://en.wikipedia.org/wiki/Woldemar_Voigt). In the Lorentz transform the time dilation is gamma and in the Voigt transform it is gamma². So I wonder what would happen if you started with a clock at a 45º angle. Could you get a time dilation between gamma and gamma²? It seems that the actual time dilation follows the Lorentz transform, but I wonder if there is some logical reason to choose it over the Voigt. -Dale
Now you sound like an ID'er. Mincing with words does not alter the basis of your arguement. Or will you state here that your presentation is somehow in conflict with the assumptions and/or conclusions of SRT. Please Register or Log in to view the hidden image!
The only assumption (clearly identified) is that the speed of light is the same in all frames. No conclusions have been presented, so it's not in conflict with anything, yet. Come one, Mac, put up or shut up. You've said that invariant c doesn't imply length contraction... now's your chance to prove it.
*Sigh* It looks like Mac doesn't want to play. Would anyone else like to have a go? Please Register or Log in to view the hidden image!We need to come up with some way to relate the distances the light flashes travel to the distances between the device and the mirrors. We know that each flash has the same round trip time, and we're assuming that each flash moves at the same speed for the whole trip.
In addition to the constant c, I assume the variables are named as follows... v (velocity) t<sub>sub</sub> (time increments at rest), also t'<sub>sub</sub> (time increments in motion) N (vertical dimension of light clock at rest), also N' (for motion) W (horizontal dimension of light clock), also W' (for motion) ...Plus these lengths which only apply to the clock in motion AC CD AB BD
Hi Neddy, welcome along! N and W specify the dimensions in motion. At rest, the dimensions are 1m by 1m. Also, we really don't need to consider the device's rest frame at all. The only question to be answered is "are N and W the same?", and we can do that directly in the frame in which the device is moving.
Thanks, Pete. So, in addition to the constant c, we have... v t N W AC CD AB BD I'm going to go out on a limb here and postulate that, at v=0... v = 0 N = 1m W = 1m AC = N CD = N AB = W BD = W
