Spacetime diagrams and the General Theory of Relativity
Before talking about the general relativity, we must consider some new idioms like:
"Spacetime diagram": It is a graph of a particle's space and time coordinates.
"World line": A line in spacetime diagram that shows the motion of a particle through the spacetime.
Examples:
A world line of a particle at rest or moving at a constant velocity is a straight line.
A world line of an accelerated particle is a curve.
Now back to the general relativity, this theory was developed by "Albert Einstein" to cover the cases of the accelerated frames of reference (not the frames at const. velocity like the special relativity).
He found that there is a relation between the general relativity and the (gravitation), How?
Since the world line of an accelerated particle is curved, a particle moving under the effect of gravity must have a curved world line in spacetime .
Hence, the mass that is responsible for causing the gravitational field must warp the spacetime to make the world lines of spacetime curved.
To imagine the warping, consider a rubber sheet with a rectangular grid painted on it.
A small ball (m) moves in a straight line on the rubber sheet, while a big metallic ball (M) distorts the shape of the rubber sheet (and the grid).
Now the small ball (m) is no longer moves in a straight line path but curves around the big ball.
So, the gravity is no more to be thought as a force in the Newtonian tradition.
Conclusions:
The General Theory of Relativity states that:
1- The laws of physics are the same in all frames of reference. (Note that there is no statement about the constancy of the velocity of light)
2- Mass (matter) warps the spacetime and spacetime tells the matter how to move.
So, gravity is the consequence of the warping of spacetime by matter.
Reference:
Fundamentals of college physics (second edition)
(Peter. J. Nolan)
Pages: 891, 892, 908, 915, 916, 917.
Raceman…
"Spacetime diagram": It is a graph of a particle's space and time coordinates.
"World line": A line in spacetime diagram that shows the motion of a particle through the spacetime.
Examples:
A world line of a particle at rest or moving at a constant velocity is a straight line.
A world line of an accelerated particle is a curve.
Now back to the general relativity, this theory was developed by "Albert Einstein" to cover the cases of the accelerated frames of reference (not the frames at const. velocity like the special relativity).
He found that there is a relation between the general relativity and the (gravitation), How?
Since the world line of an accelerated particle is curved, a particle moving under the effect of gravity must have a curved world line in spacetime .
Hence, the mass that is responsible for causing the gravitational field must warp the spacetime to make the world lines of spacetime curved.
To imagine the warping, consider a rubber sheet with a rectangular grid painted on it.
A small ball (m) moves in a straight line on the rubber sheet, while a big metallic ball (M) distorts the shape of the rubber sheet (and the grid).
Now the small ball (m) is no longer moves in a straight line path but curves around the big ball.
So, the gravity is no more to be thought as a force in the Newtonian tradition.
Conclusions:
The General Theory of Relativity states that:
1- The laws of physics are the same in all frames of reference. (Note that there is no statement about the constancy of the velocity of light)
2- Mass (matter) warps the spacetime and spacetime tells the matter how to move.
So, gravity is the consequence of the warping of spacetime by matter.
Reference:
Fundamentals of college physics (second edition)
(Peter. J. Nolan)
Pages: 891, 892, 908, 915, 916, 917.
Raceman…
posted by scientific @ 9:33 AM
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