General metric and flat metric

In summary, the flat metric describes a flat spacetime with no significant gravitational effects, while the general metric can describe a spacetime with non-zero curvature and gravitational effects.
  • #1
Tony Stark
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What is the difference between General metric gαβ and flat metric ηβα in GR?
Elaborate answers are appreciated.
 
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  • #2
The metric tensor describes the geometry of spacetime in a coordinate-independent way. One very important special case is the metric tensor that describes a flat (no significant gravitational effects) spacetime; the ##\nu_{\alpha\beta}## that you're calling the "flat metric" are the components of that metric tensor written in Minkowski coordinates. You could use a different set of coordinates (Rindler or spherical or...) and the components would come out looking completely different, but it would still be the same flat spacetime.
 
  • #3
Nugatory said:
The metric tensor describes the geometry of spacetime in a coordinate-independent way. One very important special case is the metric tensor that describes a flat (no significant gravitational effects) spacetime; the ##\nu_{\alpha\beta}## that you're calling the "flat metric" are the components of that metric tensor written in Minkowski coordinates. You could use a different set of coordinates (Rindler or spherical or...) and the components would come out looking completely different, but it would still be the same flat spacetime.
I do understand that the metric tensor used in provides independence from a particular coordinate system. But this still doesn't answer my question about the difference between general and flat metric clearly.Sorry sir.
 
  • #4
Your question is a bit like asking for the difference between an elephant and animal: all elephants are animals but not all animals are elephants.

If there exists a coordinate system in which the metric for a given spacetime takes the form ##diag(-1,1,1,1)## then the spacetime is flat; if not, then it's not.
 
  • #5
It's kind of like F=ma and F=mg. g is just an acceleration, but we give it a special symbol because it's a particular case of an acceleration that we use a lot.

Similarly, [itex]\eta_{\mu\nu}[/itex] is just a metric tensor. It does everything any other metric tensor does. It's just that it describes a case of particular interest, the one where there is no gravity, or where gravity can be neglected.

That analogy is a bit strained. but the best I can think of.
 
  • #6
Tony Stark said:
What is the difference between General metric gαβ and flat metric ηβα in GR?
Elaborate answers are appreciated.
The flat metric has 0 curvature. The general metric may not have 0 curvature.

Sorry that is not very elaborate, but the difference doesn't seem to require much elaboration.
 
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FAQ: General metric and flat metric

What is a general metric?

A general metric is a mathematical concept used to measure the distance between different points in a space. It is a fundamental tool in geometry and is used to describe the properties of different shapes and spaces.

What is a flat metric?

A flat metric is a special type of metric in which the curvature of space is zero. This means that the distance between any two points in the space is the same, regardless of the path taken between them. A flat metric is often used as a baseline for comparing other metrics and is commonly used in Euclidean geometry.

How are general metrics and flat metrics related?

General metrics and flat metrics are related in that a flat metric can be thought of as a special case of a general metric. In other words, a flat metric is a specific type of general metric where the curvature of space is zero. This allows for simpler calculations and is often used as a starting point for studying more complex metrics.

What are some common examples of general metrics?

Some common examples of general metrics include Euclidean metric, Manhattan metric, and Minkowski metric. These metrics are used to describe the properties of spaces such as flat planes, city maps, and spacetime.

Why are general metrics important in science?

General metrics are important in science because they provide a way to measure and describe the properties of different spaces and shapes. They are used in a wide range of fields, including physics, engineering, and computer science, to understand and solve complex problems. General metrics also play a crucial role in developing and testing theories and models in various scientific disciplines.

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