I Postulate of only time dependence on |ψ⟩

Click For Summary
The discussion centers on the idea that in standard quantum mechanics, particularly in Schrödinger's equation, the quantum state |ψ⟩ is primarily a function of time, implying that changes in the state are only dependent on temporal evolution. Participants question whether this time dependence is a fundamental postulate of quantum mechanics and explore the implications of considering other variables. The analogy of a socio-political-economic state evolving over time is used to illustrate that all other factors are encompassed within the state function, leaving time as the sole independent variable for analysis. The consensus suggests that if the state is complete, time remains the only variable for its evolution. This highlights the significance of time in understanding quantum states within the framework of standard quantum mechanics.
LightPhoton
Messages
42
Reaction score
3
Answers to questions like this assume that the quantum state in a Hilbert space is only a function of time, that is ##\partial_i\vert\psi(t)\rangle\neq0## only when the variable ##i## is ##t##.

Is this a postulate of standard quantum mechanics, that in Schrödinger's equation the state in abstract only depends on time?
 
Physics news on Phys.org
LightPhoton said:
Is this a postulate of standard quantum mechanics, that in Schrödinger's equation the state in abstract only depends on time?
What else could it depend on? What else could anything depend on?
 
PeroK said:
What else could it depend on? What else could anything depend on?
To explain what I mean by this. Let's take some function ##E##, say, that describes the global socio-political-economic state. That state will change over time: ##E(t)##. What else could it be a function of? Everything else is bundled into that function - population, political and economic policies etc.

The state tells you everything about a system at a point in time. The only free variable, if I can use that term, is time. You may be able to analyse the state at a point in time in many ways. But, if the state itself is complete, then time evolution is the only remaining variable.
 
  • Like
Likes bhobba and LightPhoton
For the quantum state ##|l,m\rangle= |2,0\rangle## the z-component of angular momentum is zero and ##|L^2|=6 \hbar^2##. According to uncertainty it is impossible to determine the values of ##L_x, L_y, L_z## simultaneously. However, we know that ##L_x## and ## L_y##, like ##L_z##, get the values ##(-2,-1,0,1,2) \hbar##. In other words, for the state ##|2,0\rangle## we have ##\vec{L}=(L_x, L_y,0)## with ##L_x## and ## L_y## one of the values ##(-2,-1,0,1,2) \hbar##. But none of these...

Similar threads