# Thread: Do photons travel along the gravitational lines between the emitter and receiver?

1. Join Date
Mar 2006
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206

## Do photons travel along the gravitational lines between the emitter and receiver?

Do photons travel along the gravitational lines between the emitter and receiver?
Does such a traveling along the gravitational lines interpret the Doppler shift?

2. Photons travel along geodesics, which is the shortest distance so to say between start and finish for the photon in a space-time continuum with gravity.
This does not account for Doppler shift, because Doppler shift is caused by motion of the emitter and/or receiver.

3. Join Date
Mar 2006
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Originally Posted by tusenfem
Photons travel along geodesics, which is the shortest distance so to say between start and finish for the photon in a space-time continuum with gravity.
This does not account for Doppler shift, because Doppler shift is caused by motion of the emitter and/or receiver.
The geodesic is only a mathematical term.
Because of the motion, the Doppler shift is due to the movement of the photons along the gravitational lines.

4. Order of Kilopi
Join Date
Nov 2002
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6,208
Originally Posted by Attiyah Zahdeh
The geodesic is only a mathematical term.
Photons travel the shortest path between two points. Depending on what that path is on, the shortest distance can be a straight line or a geodesic.

Originally Posted by Attiyah Zahdeh
Because of the motion, the Doppler shift is due to the movement of the photons along the gravitational lines.
Wait a minute, a line is only a mathematical term.

Let's be realistic. You can't descibe measurement without using mathematical terms. Also, I think you are thinking of locations of equal gravitational potential, not gravitational lines.

Photons are not limited to "gravitational lines". Their paths can go along or cut across locations of equal gravitational potential. The only requirement for massless particles is that they travel along the shortest path between two points (there, I didn't use a mathematical term to descibe the path, unless you count point as a mathematical term there, but then, you used line). Besides, doppler shift is due to motion (any kind of motion, along, through, over, against gravitational lines), and has nothing to do with a gravity.

On another note, this is the question and answer section. Don't push your ATM ideas (Doppler shift is due to photons moving along gravitational lines) in the guise of asking a question, then rebutting the answer you get.

5. And I even gave an explicit definition of what a geodesic is in layman's terms!

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