Frame dragging and Light speed

[narrator]

From http://en.wikipedia.org/wiki/Frame-dragging" :

"Under the Lense–Thirring effect, the frame of reference in which a clock ticks the fastest is one which is rotating around the object as viewed by a distant observer. This also means that light traveling in the direction of rotation of the object will move around the object faster than light moving against the rotation as seen by a distant observer."

Is this a speed change to light wrt itself? Is the observation of the "distant observer" different to an observer sitting on the object?

Side question: Is the location of the object, the observer and the traveling light what is meant when people talk about a "coordinate chart"?

 

[Drakkith]

The change is due to space itself bing dragged around the rotating object. This drag would affect the time it takes for light to travel past the object because space itself is being altered. Locally the speed of light is the same.

 

[bcrowell]

Is this a speed change to light wrt itself?

Not sure what you mean by "wrt itself." The velocity of a physical object with respect to itself is always zero. You can't have a frame of reference moving with a beam of light, so the velocity of light with respect to itself isn't zero, it's just undefined.

Side question: Is the location of the object, the observer and the traveling light what is meant when people talk about a "coordinate chart"?

No, GR doesn't have global frames of reference like that. A coordinate chart means a set of coordinates that label every event in a certain region of spacetime.

 

[narrator]

Thanks folks.. understandable and makes sense :)

 

[sardar]

I can provide a response to this content. Frame dragging and light speed are both concepts that have been extensively studied and observed in the field of physics. Frame dragging, also known as the Lense-Thirring effect, is a phenomenon that occurs when a massive rotating object, such as a planet or a black hole, "drags" the surrounding spacetime with it, causing a distortion in the fabric of spacetime. This distortion can have an impact on the behavior of objects, including light, in the vicinity of the rotating object.

The statement from the Wikipedia article is referring to the fact that the frame of reference in which a clock ticks the fastest is one that is rotating around the object. This means that time appears to move slower for an observer on the rotating object compared to a distant observer. This also has an effect on the speed of light. Light traveling in the direction of rotation of the object will appear to move faster to a distant observer compared to light moving against the rotation.

To answer the first question, this is not a speed change of light relative to itself. The speed of light remains constant in all frames of reference, as per Einstein's theory of relativity. However, the observed speed of light can appear to be different for different observers due to the effects of frame dragging.

As for the second question, the observation of a distant observer will be different compared to an observer sitting on the rotating object. This is because the frame of reference for the two observers is different, and therefore their perception of time and speed will also be different.

Regarding the side question, a coordinate chart is a mathematical representation of the coordinates of different points in a given spacetime. In this context, the location of the object, the observer, and the traveling light can all be represented on a coordinate chart to better understand the effects of frame dragging and light speed.