Motion equation in quantum mechanics?

In summary, von Neumann's work shows that the motion equation must be: dA/dt=[H,A] where H-Hamintonian,A-operator of any observation. The dynamics of time is energy, and the translation symmetry in time relates with Hamintonian. If time t is local flow of vector H, then following Lie derivative we have the motion equation dA/dt=[H,A].
  • #1
ndung200790
519
0
Please teach me this:
Why the motion equation must be:dA/dt=[H,A] where H-Hamintonian,A-operator of any observation,because with a local flow t(time) of vector X in a manifold we can write the Lie derivative:dA/dt=[X,A].(Where we consider time t as one-parameter group and as local flow of some operator X)
Thank you very much in advanced.
 
Physics news on Phys.org
  • #2
It is not equation of motion it states time evolution of a state under operator A. After studying it, it comes out to be analogus(or same) to classical equations of motion (Ehernfest theorem).
You need to thoroughly study foundations of mathematical aspects applied to quantum mechanics. von Neumann's work might help.
 
  • #3
ndung200790 said:
Why the motion equation must be:dA/dt=[H,A] where H-Hamintonian,A-operator of any observation

An essentially trivial derivation is in any decent textbook on quantum mechanics.
What is it that you don't get?
 
  • #4
I would like to derive all equations:Schrodinger,Klein-Gordon,Dirac equation from this"motion" equation.It seem to me that dynamics of time is energy,the translation symmetry in time relate with Hamintonian.So if time t is local flow of vector H,then following Lie derivative we have the motion equation dA/dt=[H,A].
 
  • #5
ndung200790 said:
I would like to derive all equations:Schrodinger,Klein-Gordon,Dirac equation from this"motion" equation.It seem to me that dynamics of time is energy,the translation symmetry in time relate with Hamintonian.So if time t is local flow of vector H,then following Lie derivative we have the motion equation dA/dt=[H,A].

For these equation, the relevant dynamics is i hbar psidot = H psi.
H = p^2/2m +V(x) gives Schroedinger,
H=sqrt(p^2+m^2) gives the physical (positive energy) part of Klein-Gordon,
H=gamma_0(gamma dot p + m) gives Dirac (with both physical and unphysical part; the physical part is obtained by multiplying with a projector to E>=0).

dA/dt=[H,A] holds in each of these cases for arbitrary A if one changes from the Schroedinger picture to the Heisenberg picture according to the standard recipe.

I'd like to suggest that you get more practice in standard QM before you explore your own conjectures about how to structure the standard material.
 
  • #6
Thank you very much for your kind helping and kind advice
 

FAQ: Motion equation in quantum mechanics?

What is the Schrödinger equation and how is it used in quantum mechanics?

The Schrödinger equation is a fundamental equation in quantum mechanics that describes the evolution of a quantum system over time. It is a differential equation that relates the time-dependent wavefunction of a particle to its energy and potential. The Schrödinger equation is used to calculate the probability of finding a particle in a particular state at a specific time.

What is the difference between classical mechanics and quantum mechanics?

Classical mechanics is a set of physical laws that describe the motion of macroscopic objects, while quantum mechanics is a theory that describes the behavior of particles at the atomic and subatomic level. In classical mechanics, the state of a system can be precisely determined, whereas in quantum mechanics, the behavior of particles is described by probabilities and uncertainties.

How do the Heisenberg uncertainty principle and quantum uncertainty principle differ?

The Heisenberg uncertainty principle states that it is impossible to simultaneously know the exact position and momentum of a particle. On the other hand, the quantum uncertainty principle states that it is impossible to know the exact value of two complementary observables, such as position and momentum, at the same time. The Heisenberg uncertainty principle is a specific case of the more general quantum uncertainty principle.

What is the role of wavefunctions in quantum mechanics?

Wavefunctions are mathematical functions that describe the quantum state of a particle. They contain all the information about the particle's position, momentum, and energy. In quantum mechanics, the square of the wavefunction gives the probability of finding a particle in a particular state. Wavefunctions are a crucial concept in understanding the behavior of particles in quantum mechanics.

How does the probability interpretation of quantum mechanics differ from classical mechanics?

In classical mechanics, the state of a system can be precisely determined, whereas in quantum mechanics, the behavior of particles is described by probabilities. This means that in quantum mechanics, there is an inherent uncertainty in the outcome of measurements, while in classical mechanics, there is no uncertainty. The probability interpretation of quantum mechanics is necessary to explain the behavior of particles at the atomic and subatomic level.

Similar threads

Replies
27
Views
2K
Replies
6
Views
2K
Replies
12
Views
1K
Replies
6
Views
1K
Replies
44
Views
4K
Replies
8
Views
2K
Replies
5
Views
2K
Back
Top