Light Curve Space: Maintaining Speed Constant

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if light is traveling by a curved space, for example near the sun, how can it maintain speed? shouldn t go slower? to keep the speed constant in a curve you have to accelarate...
 
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When working with curved spaces, you have to generalize your definition of a straight line path. Specifically, in a curved space, light will travel along a "geodesic" which is the generalization of a straight line to curved space. A geodesic is the shortest path you can take between two points in a curved space, just like a straight line is the shortest path between two points in flat space.

So, You shouldn't think of the light traveling through curved space as if the light was traveling in flat space and turning around a curve. Instead, its the space itself that is bending.

Think about a light ray traveling in flat space. It travels the shortest path between two points, a straight line (the geodesic in flat space) and is not accelerating at all. Agree? Now the presence of the massive sun intrinsically warps the space itself, changing the geodesic the light will travel. But the light still travels along the geodesic, the shortest path.

A more familiar analogy may help: Think about walking in a "straight line" from Boston to Seattle. In reality you are walking along a curved path along the surface of the earth, but to you, stuck in the curved space of the Earth's surface, the path "feels" equivalent to a straight line. i.e. its the shortest path you can find.
 
Also note the difference between speed and velocity is that velocity is a vector quantity which refers to direction. Speed only has magnitude.

So light travels at a constant speed, even though its velocity may change.

Consider a threoretical, perfect planet orbiting a perfect star. The planet orbiots at a constant angular velocity, its speed stays the same, although its linear velocity is continually changing with its direction.
 
Thanks to both. I´ve got it now!
 
In this video I can see a person walking around lines of curvature on a sphere with an arrow strapped to his waist. His task is to keep the arrow pointed in the same direction How does he do this ? Does he use a reference point like the stars? (that only move very slowly) If that is how he keeps the arrow pointing in the same direction, is that equivalent to saying that he orients the arrow wrt the 3d space that the sphere is embedded in? So ,although one refers to intrinsic curvature...
ASSUMPTIONS 1. Two identical clocks A and B in the same inertial frame are stationary relative to each other a fixed distance L apart. Time passes at the same rate for both. 2. Both clocks are able to send/receive light signals and to write/read the send/receive times into signals. 3. The speed of light is anisotropic. METHOD 1. At time t[A1] and time t[B1], clock A sends a light signal to clock B. The clock B time is unknown to A. 2. Clock B receives the signal from A at time t[B2] and...
So, to calculate a proper time of a worldline in SR using an inertial frame is quite easy. But I struggled a bit using a "rotating frame metric" and now I'm not sure whether I'll do it right. Couls someone point me in the right direction? "What have you tried?" Well, trying to help truly absolute layppl with some variation of a "Circular Twin Paradox" not using an inertial frame of reference for whatevere reason. I thought it would be a bit of a challenge so I made a derivation or...

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