Definition of Poisson Bracket: {f,g}

OVE IS THE CONVERSATION. In summary, the correct definition for a Poisson bracket is {f,g} = df/dq.dg/dp - df/dp.dg/dq. However, some books may use the other definition, {f,g} = df/dp.dg/dq - df/dq.dg/dp, which is simply the first one multiplied by -1. Both definitions are valid, but the second one is more commonly used.
  • #1
Pyroadept
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Hi, what is the correct definition for a Poisson bracket?
Some books say it is:

{f,g} = df/dp.dg/dq - df/dq.dg/dp

but others say it is:

{f,g} = df/dq.dg/dp - df/dp.dg/dq

One is the other multiplied by -1.
Which is the correct definition?


Thanks for any help.
 
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  • #2
Pyroadept said:
Hi, what is the correct definition for a Poisson bracket?
Some books say it is:

{f,g} = df/dp.dg/dq - df/dq.dg/dp

but others say it is:

{f,g} = df/dq.dg/dp - df/dp.dg/dq

One is the other multiplied by -1.
Which is the correct definition?


Thanks for any help.

You CAN use either the first definition or the other one and this only depends on author's style though if I were you, I would take the second one for granted in being more common and true.

AB
 

What is a Poisson bracket?

A Poisson bracket is a mathematical operation that is used to describe the dynamics of a physical system. It is denoted by {f,g} where f and g are functions of the system's variables.

What is the purpose of a Poisson bracket?

The main purpose of a Poisson bracket is to describe the evolution of a system over time by measuring the change in a given quantity with respect to another quantity.

How is a Poisson bracket calculated?

A Poisson bracket is calculated by taking the partial derivatives of the two functions f and g with respect to the system's variables and then multiplying them together. The result is a new function that represents the rate of change between the two functions.

What are some real-world applications of Poisson brackets?

Poisson brackets have a wide range of applications in physics, mechanics, and engineering. They are used to describe the behavior of physical systems such as particles, fluids, and fields. They are also used in the study of chaotic systems and in the development of mathematical models for various physical phenomena.

What are the properties of a Poisson bracket?

The Poisson bracket has several key properties, including bilinearity, skew-symmetry, and the Jacobi identity. These properties allow for the Poisson bracket to accurately describe the dynamics of a system and make it a useful tool in the study of physical systems.

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