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acme036

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The uncertainty in this principle is talking about uncertainty of measurement or particle itself?

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- Thread starter acme036
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In summary, the uncertainty principle, a fundamental characteristic of nature, states that it is impossible to simultaneously know the precise position and momentum of a quantum system. This applies to both massive accelerated particles and particles bound in atoms. The principle is not affected by the act of observation, but rather reflects the inherent probabilistic nature of quantum particles. It sets a limit on the precision with which these two observables can be known and is a fundamental concept in quantum mechanics.

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acme036

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The uncertainty in this principle is talking about uncertainty of measurement or particle itself?

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acme036 said:The uncertainty in this principle is talking about uncertainty of measurement or particle itself?

They HUP has nothing to do with our ability to measure things, it is a fundamental characteristic of nature.

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Chase

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phinds said:They HUP has nothing to do with our ability to measure things, it is a fundamental characteristic of nature.

But is it the act of observing it that creates the uncertainty or is the uncertainty always there, regardless of whether we're observing it or not?

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Nugatory

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Chase said:But is it the act of observing it that creates the uncertainty or is the uncertainty always there, regardless of whether we're observing it or not?

The uncertainty is always there, in the sense that it is impossible to prepare a quantum system in such a way that two incompatible observables both have definite values.

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dauto

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Maui

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Simply put, it is not possible to both know where a particle is and how fast it moves about.

But i wonder what constraints the HUP poses for colliders where you know the location of the particle because you are guiding it so you can collide it with other particles while you know its speed/momentum and energy/time. And since the momentum is very high, its wavelength must be very low and some interpret this as a prerequisite for little to no wave bahavior(position uncertainty).

Does the HUP apply in the same manner to a massive accelerated particle as it does to an electron bound in an H atom? Or is there a semi classical situation of an acclerated particle where the HUP gradually fades away giving way to classicality?

But i wonder what constraints the HUP poses for colliders where you know the location of the particle because you are guiding it so you can collide it with other particles while you know its speed/momentum and energy/time. And since the momentum is very high, its wavelength must be very low and some interpret this as a prerequisite for little to no wave bahavior(position uncertainty).

Does the HUP apply in the same manner to a massive accelerated particle as it does to an electron bound in an H atom? Or is there a semi classical situation of an acclerated particle where the HUP gradually fades away giving way to classicality?

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jtbell

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acme036 said:The uncertainty in this principle is talking about uncertainty of measurement or particle itself?

'Uncertainty principle' is a term I'd rather not use. As a result of the mathematical formalism of Quantum Mechanics, this is a theorem about the bounds of mean square deviations of 2 observables described through self-adjoint operators. The virtual statistical ensemble theory links the matrix elements appearing in the theorem to the results of perfect/unperturbed measurements of the 2 observables on the virtual statistical ensemble via the Born rule.

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acme036 said:The uncertainty in this principle is talking about uncertainty of measurement or particle itself?

Please read this thread:

https://www.physicsforums.com/showthread.php?t=737543

Zz.

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bhobba

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Chase said:But is it the act of observing it that creates the uncertainty or is the uncertainty always there, regardless of whether we're observing it or not?

Its a theorem about observables and the outcome of observations. What a particle is etc when not being observed is anyone's guess because the theory is silent about it.

Thanks

Bill

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bhobba

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dextercioby said:'Uncertainty principle' is a term I'd rather not use. As a result of the mathematical formalism of Quantum Mechanics, this is a theorem about the bounds of mean square deviations of 2 observables described through self-adjoint operators. The virtual statistical ensemble theory links the matrix elements appearing in the theorem to the results of perfect/unperturbed measurements of the 2 observables on the virtual statistical ensemble via the Born rule.

Spot on.

And I don't like it either, but like wave-function is enshrined - sigh.

Thanks

Bill

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Maui said:Simply put, it is not possible to both know where a particle is and how fast it moves about.

No, not really. You CAN know that for a single particle. What the HUP says is that you have not discovered something deterministic the way that classical physics would say you have, you've just found it for one particle. When you do EXACTLY the same experiment with another particle, classical physics says that it will do the exact same thing as the first one, but that isn't what happens and THAT is what the HUP is all about. This is discussed in the link that zapperz provided.

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Maui

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phinds said:No, not really. You CAN know that for a single particle. What the HUP says is that you have not discovered something deterministic the way that classical physics would say you have, you've just found it for one particle. When you do EXACTLY the same experiment with another particle, classical physics says that it will do the exact same thing as the first one, but that isn't what happens and THAT is what the HUP is all about. This is discussed in the link that zapperz provided.

I am not sure you can know both position and momentum for a single particle as this would imply a classical trajectory and afaik this only happens for very massive accelerated particles or as approximation of millions of detections. The relationship is given as delta x.delta p=h/2 and is a fundamental limit to the precision that these two observables can be known simultaneously for a particle. What you say seems to me an oversimplification and in qm there are plenty of them but seldom capture the essence.

What you can know about a single particle(measurement) will always be probabilistic as the particle doesn't have a well defined position and momentum.

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Drakkith

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Maui said:What you can know about a single particle(measurement) will always be probabilistic as the particle doesn't have a well defined position and momentum.

It does as soon as you detect it. Once it is detected it has no more probability.

The uncertainty principle is about predicting the momentum and position of a particle prior to detection. You can predict either the momentum or the position with an arbitrary precision, but not both. It is also about determining the position and momentum of successive identical particles.

See this post: https://www.physicsforums.com/showthread.php?t=737543#post4656668

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Maui

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Drakkith said:It does as soon as you detect it. Once it is detected it has no more probability.

The uncertainty principle is about predicting the momentum and position of a particle prior to detection. You can predict either the momentum or the position with an arbitrary precision, but not both.

That is what I was saying - you need a measurement which as a process falls outside the formalism of qm to assert that a single particle has both well defined x and p. Prior to that the particle obeys the HUP and does not have these attributes.

Heisenberg's Uncertainty Principle is a fundamental concept in quantum mechanics that states that it is impossible to know both the position and momentum of a particle with absolute certainty at the same time.

The Uncertainty Principle suggests that there are inherent limitations to our ability to measure and predict the behavior of particles at the quantum level. It challenges the traditional deterministic view of the physical world and highlights the probabilistic nature of quantum mechanics.

The mathematical expression for the Uncertainty Principle is ΔxΔp ≥ h/4π, where Δx represents the uncertainty in position, Δp represents the uncertainty in momentum, and h is Planck's constant.

No, the Uncertainty Principle is a fundamental principle of quantum mechanics and cannot be violated. It is supported by numerous experiments and is a crucial aspect of our understanding of the behavior of particles at the quantum level.

The Uncertainty Principle is closely related to other principles in quantum mechanics, such as the wave-particle duality and the principle of superposition. It also has implications for other concepts, such as the observer effect and quantum entanglement.

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