Number of different ways, particle with E and delta_E.

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In summary: No, they won't. This is because the wavefunctions of particles with zero momentum are not scattered at all.Say we scatter a spin-less charged particle of energy E and energy spread delta E off a potential. Now say we have the wave function made of different subsets of the full set (minus the highest energy) of momentum states for this spin-less charged particle of energy E and energy spread delta E. Will those wave-functions of different subsets scatter off the potential the same? Can we manipulate things so that small changes in the subsets give rise to large variations in scattering?As long as your potential is smooth and 'nice' small gaps in a set constituting your wavefunction have no effect. You may
  • #1
Spinnor
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If we prepare a particle with energy E and some small spread in energy delta E then its wave function can be expanded with some large countable set of momentum states (exclude states above some very high energy)?

If we have a very large countable set of momentum states it seems we could exclude some states and still make a very good approximation for the wave function for a particle of energy E and energy spread delta E?

Thanks for any help!
 
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Countable? Why? Continuous!

And of course, the mix of continuous states excluding some values should not cause any problems.
 
  • #3
xts said:
Countable? Why? Continuous!

And of course, the mix of continuous states excluding some values should not cause any problems.

In a large box if we exclude very high energy don't we just need a countable set?
 
  • #4
Spinnor said:
In a large box if we exclude very high energy don't we just need a countable set?
OK - in a large box, you have countable set. Don't dispute about order of infinity...
But I still can't see the problem? Yes, you may exclude a subset of measure 0 (or close to 0) and still get the same results of all statistical predictions.
 
  • #5
xts said:
OK - in a large box, you have countable set. Don't dispute about order of infinity...
But I still can't see the problem? Yes, you may exclude a subset of measure 0 (or close to 0) and still get the same results of all statistical predictions.

I'm trying understand so that I might answer the question in the title, "Number of different ways, particle with E and delta_E". If I read you correctly it seems we can have many states that are for practical purposes the same state?
 
  • #6
Spinnor said:
If I read you correctly it seems we can have many states that are for practical purposes the same state?
Sure!
If the number of possible states (number of degrees of freedom) counts - then if you prohibit some of the large number of still possible - it won't be noticeable.
In any case - prohibiting measure-0 subset won't cause any visible effects (like black lines on the spectrum)
 
  • #7
xts said:
Sure!
If the number of possible states (number of degrees of freedom) counts - then if you prohibit some of the large number of still possible - it won't be noticeable.
In any case - prohibiting measure-0 subset won't cause any visible effects (like black lines on the spectrum)

Say we scatter a spin-less charged particle of energy E and energy spread delta E off a potential. Now say we have the wave function made of different subsets of the full set (minus the highest energy) of momentum states for this spin-less charged particle of energy E and energy spread delta E. Will those wave-functions of different subsets scatter off the potential the same? Can we manipulate things so that small changes in the subsets give rise to large variations in scattering?
 
  • #8
As long as your potential is smooth and 'nice' small gaps in a set constituting your wavefunction have no effect. You may create artificial potentials, e.g. forming diffraction grid, differentiating small (but still finite) variances in your wavefunction. But even then, if the eliminated subset has measure of 0, they won't affect final outcome.
 

FAQ: Number of different ways, particle with E and delta_E.

How is the number of different ways calculated for a particle with energy E and uncertainty in energy delta_E?

The number of different ways is calculated using the formula N = exp(S), where S is the entropy of the system. Entropy is a measure of the number of microstates that a system can have for a given macrostate. In this case, the macrostate is defined by the energy E and the uncertainty in energy delta_E.

What is the significance of the number of different ways for a particle?

The number of different ways is a measure of the disorder or randomness in a system. It is related to the concept of entropy, which is a fundamental property of thermodynamic systems. The higher the number of different ways, the more disordered the system is and the more energy it has.

How does the number of different ways change as the particle's energy or uncertainty in energy changes?

The number of different ways is directly proportional to the energy and uncertainty in energy of the particle. As the energy or uncertainty increases, the number of different ways also increases. This is due to the fact that there are more possible microstates for a higher energy system.

Can the number of different ways ever be zero?

No, the number of different ways can never be zero. This is because even if a system is in its lowest energy state, there will still be at least one possible microstate for that system. Therefore, the number of different ways will always be greater than or equal to one.

How does the number of different ways relate to the probability of a particle having a certain energy?

The number of different ways is related to the probability of a particle having a certain energy through the Boltzmann distribution law, which states that the probability of a system being in a particular state is proportional to the number of different ways that state can be achieved. This means that the higher the number of different ways for a certain energy, the higher the probability of the particle having that energy.

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