Coupled nonlinear partial differential equations or simple matrices?

In summary, the conversation discusses the difficulty in finding all of Einstein's equations in one place and the struggle to understand general relativity from a mathematical standpoint. It is explained that in general relativity, matter is modeled as fields rather than particles and these fields have energy-momentum tensors. However, for the sake of simplicity, one can talk about a particle moving in curved spacetime. The question is then raised about how to construct the energy-momentum tensor for a particle using scalar values like energy and momentum.
  • #1
ilocar
17
0
Why is it impossible to find ALL of einstein's equations in one place? well I suppose its irrelevant, I'd just like to know what math I have to do to define the energy-momentum tensor for a particle if I know say... its energy and momentum, or is that illegal? I'm struggling to grasp general relativity, from a mathematical standpoint; I get it philosophically, help please :(
 
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  • #2
In general relativity matter is modeled as different sorts of fields, not particles. It is these fields that have energy momentum tensors.

However, one can talk about a particle moving in curved spacetime as an approximation. In this approximation, spacetime curvature is produced by the energy-momentum tensors of all matter except for a particular particle. The particle then moves on the "background" curved spacetime created by all other matter.

http://relativity.livingreviews.org/Articles/lrr-2004-6/
 
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  • #3
I may possibly be even more confused. the question I meant to ask was not how a particle moves but how do I take scalar values like energy and momentum and construct the matrix that defines the energy-momentum tensor, or is that something that only supercomputers, Einstein and Swartzchilde can do?
 

1. What are coupled nonlinear partial differential equations?

Coupled nonlinear partial differential equations are a type of mathematical model used to describe the relationships between multiple variables in a system. They involve differential equations, which describe the rate of change of a variable, and are "coupled" because the equations are interconnected and affect each other's behavior. The term "nonlinear" means that the equations do not have a linear relationship between the variables, making them more complex to solve.

2. How are coupled nonlinear partial differential equations different from simple linear equations?

The main difference between coupled nonlinear partial differential equations and simple linear equations is that the former involve multiple variables that are interconnected, while the latter only involve one or two variables with a linear relationship. This makes coupled nonlinear partial differential equations more complex and difficult to solve, as they require advanced mathematical techniques such as numerical methods or approximation methods.

3. What are some real-world applications of coupled nonlinear partial differential equations?

Coupled nonlinear partial differential equations are used in a wide range of fields, including physics, engineering, economics, and biology. They can be applied to model systems such as fluid dynamics, heat transfer, chemical reactions, and population dynamics. These equations are also used in computer simulations to study and predict the behavior of complex systems.

4. How are coupled nonlinear partial differential equations solved?

Solving coupled nonlinear partial differential equations is a complex task that often requires advanced mathematical techniques. Some of the most common methods include numerical methods, which use a computer to approximate the solutions, and analytical methods, which use mathematical tools to find exact solutions. Other techniques such as perturbation methods and variational methods may also be used depending on the specific problem.

5. What are simple matrices?

Simple matrices are a type of mathematical object used to represent and manipulate data. They are composed of rows and columns of numbers, and can be used to solve systems of linear equations, perform transformations, and store and analyze data. Simple matrices differ from other types of matrices in that they are square (have the same number of rows and columns) and have zeros in all positions except for the main diagonal, which contains the numbers of interest.

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