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I ran into something that caught me by suprised the other day.Please consider the derivation of the fact that light slows down in a gravitational field at ...sorry, you cannot view external links. To see them, please REGISTER or LOGINEq. (6) defines the Schwarzschild metric. Understanding the derivation means understanding the meaning of the variables in that derivation. In another forum there was an uncomfortably large number of people who didn't understand the derivation. In the end I learned that they didn't understand the physical meaning of the variables. Right now I'm curious about the general understanding of this metric and the meaning of the variables. If you don't mind me asking, those of you believe yourself knowledgeable of Schwarzschild spacetime geometry what is the meaning of the time parameter, i.e. where is the clock that reads that time located. If it could be at a multitude of places then please describe that multitude. Thank you all!

Interesting question for me, still learning gr, I knew proper time is different from coordinate time but there's more:"But the coordinate time is not a time that could be measured by a clock located at the place that nominally defines the reference frame,..."...sorry, you cannot view external links. To see them, please REGISTER or LOGINAlways more to learn...

Sure you do Pete Break it down as far as you see how.

Think of it this way. Take a right angled triangle. The hypotenuse will be the direction of travel as seen by an observer looking into a moving train. If we extend the opposite and adjacent sides to equal c then light cannot possibly travel along the hypotenuse in the same time it would have taken to move along in a straight line. This would mean a speed for light greater than c. So there has to be some contraction to compensate. So either the opposite or adjacent side has to contract. At c this would leave a straight line the triangle being compressed flat. Hence the angle of travel flattens with momentum.

What I mean is a response to your question. "Did I assume too much from the reader?"

Quote from: jeffreyH on 13/12/2013 07:10:55Think of it this way. Take a right angled triangle. The hypotenuse will be the direction of travel as seen by an observer looking into a moving train. If we extend the opposite and adjacent sides to equal c then light cannot possibly travel along the hypotenuse in the same time it would have taken to move along in a straight line. This would mean a speed for light greater than c. So there has to be some contraction to compensate. So either the opposite or adjacent side has to contract. At c this would leave a straight line the triangle being compressed flat. Hence the angle of travel flattens with momentum.Jeff - What are you talking about? I can't understand what you're trying to argue or the poin

\It is describing the apparent path of light (diagonal) as seen by a stationary observer of a beam of light directed vertically on a moving train. It is a description to show in layman's terms how time dilation must account for the extra distance the light is perceived to travel. If the two sides of the triangle that make up the right angle were extended to 299,792,458 metres each then the light path down the diagonal cannot take 1 second as this would violate the speed of light as light would have to travel faster than c. This is a good indicator of both time dilation and length contraction.

Quote from: jeffreyH\It is describing the apparent path of light (diagonal) as seen by a stationary observer of a beam of light directed vertically on a moving train. It is a description to show in layman's terms how time dilation must account for the extra distance the light is perceived to travel. If the two sides of the triangle that make up the right angle were extended to 299,792,458 metres each then the light path down the diagonal cannot take 1 second as this would violate the speed of light as light would have to travel faster than c. This is a good indicator of both time dilation and length contraction.The extra distance traveled is due to the non-Euclidean nature of the space around the sun.

Well Pete, TNS also draws people without the mathematics, and then it becomes a question of whom you want this page to be directed too.

.. those of you believe yourself knowledgeable of Schwarzschild spacetime geometry ...

Yes it's all in the coordinates Pete.

Quote from: jeffreyHYes it's all in the coordinates Pete.What is all in the coordinates, Jeff?

Depending upon the coordinate system selected the results can differ.

Quote from: jeffreyHDepending upon the coordinate system selected the results can differ.Of course. That's why it's called relativity.

This conversation has gotten so off subject that it now bears little to no resemblance of the original topic.The topic of this thread is the fact that the speed of light slows down as it passes through a gravitational field. I was asking those of you here who are knowledgeable of Schwarzschild spacetime geometry. Who here understands general relativity well enough to understand the derivation which shows that the speed of light slows down as it moves through a gravitational field?