[grip_daddy]

Originally Posted by Ester

If you use Lorentzian transformations which are slightly more complicated than Galileo's transformations, then yes, time also intervenes.

Then pulling an object from the sun using a solid object (light travels slower in solid than in vacuum) will not be instantenous.

[YB*]

Originally Posted by grip_daddy

Then pulling an object from the sun using a solid object (light travels slower in solid than in vacuum) will not be instantenous.

Hmmm I disagree completely with this standpoint and i will explain myself in relation to jarambas original question: for ease of understanding lets make some distance assumptions, lets assume the sun is 1,000,000 miles from earth.

here we have a straight rod thats 1,000,000 miles long attached to an object on the suns surface, assuming that my rod has awesome tenacity and that it will remain straight and will not bend or stretch, if i was to shift the end of the rod by 2 metres on earth, what possible reason would there be for any delay with what happens on the sun? How could it not be instantaneous?? from an actual point of view, not from a viewing point of view (actual seeing of the movement)

[grip_daddy]

YB*

How is the force transmitted? Not by particles that make up the rope? At what speed? Then we can know after how long.

[YB*]

Originally Posted by grip_daddy

YB*

How is the force transmitted? Not by particles that make up the rope? At what speed? Then we can know after how long.

I went further and revised his example because usage of rope left a lot of argument because our construct of a rope means, has elastic qualities, thats why my example reads tenacious rod.

Anyways the force is applied by hand motion, moving the end in earth 2 metres backwards or even pushing 2 metres forwards, we can even say 1 foot (12") either way, but its a hand action.

[grip_daddy]

Originally Posted by YB*

I went further and revised his example because usage of rope left a lot of argument because our construct of a rope means, has elastic qualities, thats why my example reads tenacious rod.

Anyways the force is applied by hand motion, moving the end in earth 2 metres backwards or even pushing 2 metres forwards, we can even say 1 foot (12") either way, but its a hand action.

Assumption is that any action from the earth's end will require a zero time interval to reach the sun's end. This assumption posit that our action will travel at an infinite speed in a solid medium. I don't think so.

Let me get something about phonons in metals to explain about the force transmission in a solid.

[opiche]

The Speed of Force? Text - Physics Forums Library

[ernestombayo7]

Originally Posted by jaramba

I posed these questions after trying to understand what could happen if the Sun disappeared instantaneoulsy from space. Will Earth veer off at a tangent to the orbit path instantaneuosly or the Sun absence will register on earth after some finite time?

If the sun suddenly disappeared:

1.We would see/notice only after 8 minutes as the last rays of light before the sun disappears reach us.
2.The Earth will start veering off course immediately.Space and Time are interlinked to form Space-time continuum.The bending of space is what creates the gravitational pull of the sun.Imagine placing a big bowling bowl on a water bed.and a small marble to represent the earth revolving round it.
The water bed is space and time.The bowling ball is the sun.The marble is earth.If you suddenly remove the bowling bowl while the marble is going round it,the marble will instantaneously change course.Because there is no downward pulling force caused by the bowling ball on the water bed.
So if the sun were to suddenly disappear,the earth would start to change course immediately.

NB:There have been no successful calculations of the speed of gravity.

[ATLian]

I was studying the the two relativity theories of Einstein and I gathered that the speed of light cannot be surpassed.

From what I've read, c cannot be surpassed in naturally existing conditions. Lakini in lab conditions, it not only can be surpassed but it has been surpassed.



For example assume there is a rope long enough to reach the Sun, and someone standing on earth tries to apply force by pulling an object tied on the rope on the Sun surface; will the object move instantaneously the rope is pulled? Or it will take about 8 minutes (time light strikes earth from Sun) for the object to move?

I'm sure we all know these little table-top devices on the below snap. They're actually called Newton's Pendulums.



When you swing the ball on one end and smack the other balls, the ball on the other end swings out instantaneously. That's because it's a tiny pendulum and the force travels through it almost instantaneously. But now imagine if you had a Newton Pendulm that was 8.5 light minutes long (distance from the earth to the sun). Also imagine that no force will be lost to friction or anything like that, and any force applied by the first ball will be the exact same force to reach the last ball.

If you pulled one ball on the earth-side, then the last ball on the sun-side wouldn't swing away immediately. That's coz the force from the first ball has to travel through that great distance before registering on the other ball. If it happened immediately, then that is stating that "force waves" travel faster than light, which is not true.

Using that same logic, if you pull the rope, then the force will fly through the rope for 8.5 minutes before the thing on the other side experiences a tugging effect.