Poisson Brackets Explained: Understanding the Relationship between {x,p} = 1"

In summary, the conversation discusses the calculation of the Poisson brackets for {x,p} and how it should equal 0. The individual derivatives are calculated and plugged into the formula to get a final value of 1. There is some confusion about the values of (dx/dp) and (dp/dx) and the realization that p is velocity dependent. This leads to the conclusion that {x,p} = 1 is the correct result.
  • #1
gijoe
6
0
can anyone tell me why the poisson brackets for {x,p} = 1 ..from (dx/dx)(dp/dp) - (dx/dp)(dp/dx)... shouldn this equal 0??
 
Physics news on Phys.org
  • #2
I don't know why you think it should be 0.

Calculate each derivative and plug the values into the formula. You should get 1. Remember that x and p are independent.
 
  • #3
dx/dx = 1. dp/dp = 1. dx/dp = 0. dp/dx = 0. 1 - 0 = 1. Which of these is not clear to you?
 
  • #4
oh right, my lecture notes said that (dx/dp) = 1... i then assumed that (dp/dx) = 1.. oh yes and p is velocity dependent, now i get it... thanks!
 
  • #5
{x,p} = 1 therefore
(dx/dx)(dp/dp) - (dx/dp)(dp/dx)=i
 

1. What are Poisson brackets?

Poisson brackets are a mathematical concept used in classical mechanics to represent the fundamental relationship between physical quantities, such as position and momentum, in a physical system.

2. How are Poisson brackets used in physics?

Poisson brackets are used to describe the dynamics of a system by quantifying the rate of change of one physical quantity with respect to another. They are particularly useful in Hamiltonian mechanics, where they are used to derive the equations of motion.

3. What is the mathematical representation of a Poisson bracket?

The mathematical representation of a Poisson bracket is {A,B} = ∑ᵢ ∂A/∂qᵢ ∂B/∂pᵢ - ∂A/∂pᵢ ∂B/∂qᵢ, where A and B are physical quantities, qᵢ and pᵢ represent the position and momentum variables, and the ∂ symbol represents partial differentiation.

4. What is the significance of Poisson brackets in symplectic geometry?

Poisson brackets play a central role in symplectic geometry, which is the mathematical framework used to describe the geometry of classical mechanics. They are used to define the symplectic structure of a phase space, which is a mathematical space that represents all possible states of a physical system.

5. How are Poisson brackets related to quantum mechanics?

Poisson brackets are closely related to commutators in quantum mechanics. In fact, in the classical limit, the Poisson bracket of two classical quantities is equal to the commutator of the corresponding quantum operators. This connection allows for the translation of classical equations of motion to their quantum counterparts.

Similar threads

  • Introductory Physics Homework Help
Replies
5
Views
240
  • Introductory Physics Homework Help
Replies
21
Views
1K
  • Classical Physics
Replies
8
Views
813
Replies
1
Views
1K
  • Electromagnetism
Replies
2
Views
842
  • Introductory Physics Homework Help
Replies
1
Views
801
  • Differential Geometry
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
9
Views
3K
Replies
3
Views
589
  • Introductory Physics Homework Help
Replies
3
Views
1K

Back
Top