B Types of Metrics: Background & Reference Explained

[windy miller]

As I understand it relativity is built using a mathematical framework called a metric. ButI have heard some scientists refer to things like a background metric and a reference meteoric. Can anyone explain what these are?

 

[PAllen]

Background metric is used to consider the motion of a body considered to be 'small'. In the simplest case, the small body is treated as a 'test particle' moving as a geodesic in the background metric. On the other hand, to consider backreaction from gravitational wave emission without the full machinery of numerical relativity, the small body is considered to provide a metric perturbation on top of the background metric. These are just approximation techniques. They do not suggest there are really different types of metrics in the theory of General Relativity.

I have not heard of the term 'reference metric', so I can't answer that question.

 

[windy miller]

Background metric is used to consider the motion of a body considered to be 'small'. In the simplest case, the small body is treated as a 'test particle' moving as a geodesic in the background metric. On the other hand, to consider backreaction from gravitational wave emission without the full machinery of numerical relativity, the small body is considered to provide a metric perturbation on top of the background metric. These are just approximation techniques. They do not suggest there are really different types of metrics in the theory of General Relativity.

I have not heard of the term 'reference metric', so I can't answer that question.

thanks