Is dt/ds always positive in General Relativity?

Thread starter deadringer
Start date Apr 9, 2007
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General General relativity Relativity

In summary, General Relativity is a theory of gravity that explains how matter and energy interact with space and time to create the force of gravity. It differs from Newton's theory by describing gravity as the curvature of space and time rather than a force between objects. This theory has real-world applications, such as predicting the behavior of objects in our universe and being essential for modern technologies like GPS. While it is not yet compatible with quantum mechanics, it has been extensively tested and confirmed through various observations and experiments.

Apr 9, 2007

deadringer

Is it always true that dt/ds is always positive, where t is the coordinate time and s is the proper time? I suspect his is the case, but am not sure why.

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Apr 9, 2007

Dick

Science Advisor

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No, it's not true. dt^2-dx^2=ds^2. You can reverse coordinate time freely t->-t. After all, it's just a coordinate.

1. What is General Relativity?

General Relativity is a theory of gravity developed by Albert Einstein in the early 20th century. It describes how matter and energy interact with space and time to create the force of gravity.

2. How does General Relativity differ from Newton's theory of gravity?

Newton's theory of gravity described gravity as a force between two objects with mass. General Relativity, on the other hand, explains gravity as the curvature of space and time caused by the presence of mass and energy.

3. What are some real-world applications of General Relativity?

General Relativity has been used to make accurate predictions about the behavior of objects in our universe, such as the bending of light near massive objects and the existence of black holes. It also plays a crucial role in modern technologies such as GPS systems.

4. Is General Relativity compatible with quantum mechanics?

Currently, General Relativity and quantum mechanics are two separate theories that have not been successfully unified. However, many scientists are working towards a theory of quantum gravity that would reconcile these two theories and provide a more complete understanding of the universe.

5. How has General Relativity been tested and confirmed?

General Relativity has been extensively tested and confirmed through observations and experiments, such as the prediction and subsequent observation of gravitational lensing, the precision of the GPS system, and the detection of gravitational waves. These tests have shown that General Relativity accurately describes the behavior of gravity in our universe.