Can Structure Constants Define a Metric in a 10D Lie Algebra?

In summary, the conversation discusses the possibility of building a metric from the structure constants of a 10 dimensional Lie algebra over a field of functions. It is mentioned that a symmetric bi-linear form, known as the Killing-Cartan Form, can be formed through contraction of the structure constants. There is also a question about whether there are any other contractions or tensors that can be formed from the structure constants over a field of functions. The response states that the field does not matter, but rather the non-degeneracy of the Killing form, which defines a metric on the root spaces.
  • #1
jfy4
649
3
Hi,

Let's say I have a 10 dimensional Lie algebra over some field of functions, something along the lines of at least twice differentiable with twice differentiable inverses. The structure constants have inputs from this field. Is it possible to build a metric from these structure constants?

I have seen that a symmetric bi-linear form (the Killing-Cartan Form) that can also be non-degenerate for semi-simple algebras can be formed through contraction of the structure constants [itex]\kappa f^{\alpha\beta}_{\quad\gamma} f^{\delta\gamma}_{\quad\beta}=K^{\alpha\delta}[/itex]. Are there any other contractions or tensors one can form from structure constants over a field of functions (something other than [itex]\mathbb{R}[/itex] or [itex]\mathbb{C}[/itex])?

Thanks,
 
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  • #2
The field doesn't matter. What matters is, whether the Killing form is non degenerate or not, i.e. whether the Lie algebra is semisimple or not. I won't call the Killing form a metric on the structure constants, or any other attempt to define a metric on this finite set: Why? The Killing form defines a metric on the root spaces.
See: https://www.physicsforums.com/insights/lie-algebras-a-walkthrough-the-basics/
 

Related to Can Structure Constants Define a Metric in a 10D Lie Algebra?

1. What are structure constants in physics?

Structure constants are mathematical values used to describe the properties and relationships among physical systems. They are often used in the study of symmetry and conservation laws in physics.

2. How are structure constants related to metric?

Structure constants are used to define the metric tensor, which is a mathematical object that describes the distance and angle relationships in a given space. The metric tensor is essential in understanding the geometry and dynamics of a physical system.

3. What is the significance of structure constants in general relativity?

In general relativity, structure constants play a crucial role in defining the curvature of spacetime and the equations of motion for particles and fields. They are essential for understanding the gravitational interactions between objects.

4. Can structure constants be measured experimentally?

Yes, structure constants can be measured experimentally by studying the properties and interactions of physical systems. These measurements can help verify or refine existing theories and models in physics.

5. Are structure constants universal or do they vary in different physical systems?

Structure constants are specific to each physical system and can vary depending on the symmetries and properties of that system. However, certain structure constants, such as the speed of light, are considered universal constants in physics.

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