Quantcast
  • Register
PhysicsOverflow is a next-generation academic platform for physicists and astronomers, including a community peer review system and a postgraduate-level discussion forum analogous to MathOverflow.

Welcome to PhysicsOverflow! PhysicsOverflow is an open platform for community peer review and graduate-level Physics discussion.

Please help promote PhysicsOverflow ads elsewhere if you like it.

News

PO is now at the Physics Department of Bielefeld University!

New printer friendly PO pages!

Migration to Bielefeld University was successful!

Please vote for this year's PhysicsOverflow ads!

Please do help out in categorising submissions. Submit a paper to PhysicsOverflow!

... see more

Tools for paper authors

Submit paper
Claim Paper Authorship

Tools for SE users

Search User
Reclaim SE Account
Request Account Merger
Nativise imported posts
Claim post (deleted users)
Import SE post

Users whose questions have been imported from Physics Stack Exchange, Theoretical Physics Stack Exchange, or any other Stack Exchange site are kindly requested to reclaim their account and not to register as a new user.

Public \(\beta\) tools

Report a bug with a feature
Request a new functionality
404 page design
Send feedback

Attributions

(propose a free ad)

Site Statistics

205 submissions , 163 unreviewed
5,047 questions , 2,200 unanswered
5,345 answers , 22,709 comments
1,470 users with positive rep
816 active unimported users
More ...

  Does the uncertainty principle require information to actually not exist, or just be inaccessible?

+ 0 like - 0 dislike
666 views

I understand that the uncertainty principle places limits on how precisely certain pairs of properties can be measured. But does this require that the information about these properties actually not exist in the first instance? That is, I understand that the uncertainty principle goes beyond a simple observer phenomenon, but It's not clear where the boundaries are, and specifically, whether it applies to information about properties, as opposed to the properties themselves. For example, does the principle assert the non-existence of information about a particle's position and momentum, or rather, does it imply that this information cannot be accessed by any observer?

asked Mar 12, 2018 in Theoretical Physics by Feynmanfan85 (0 points) [ no revision ]

1 Answer

+ 0 like - 0 dislike

QM is an intrinsically* probabilistic theory. So if the system is in a generic (non-eigenstate) state, you do have information about any specific observable A, but it is a distribution of possible values. 
Repeated experiments to measure that observable on identically prepared initial states will yield a spread of values.

The Heisenberg-Robertson uncertainty principle says that if you choose your initial state to minimise your uncertainty (standard deviation) in observable A, then you will end up increasing your uncertainty in an observable B that does not commute with A. 

(*The probabilistic element of QM is not as in classical statistical mechanics where particles have definite positions and momenta described by deterministic Newtonian mechanics. In QM there is no underlying local hidden variable theory --- this possibility has been ruled out by Bell inequality experiments).

answered Mar 26, 2018 by rparwani (0 points) [ no revision ]

Your answer

Please use answers only to (at least partly) answer questions. To comment, discuss, or ask for clarification, leave a comment instead.
To mask links under text, please type your text, highlight it, and click the "link" button. You can then enter your link URL.
Please consult the FAQ for as to how to format your post.
This is the answer box; if you want to write a comment instead, please use the 'add comment' button.
Live preview (may slow down editor)   Preview
Your name to display (optional):
Privacy: Your email address will only be used for sending these notifications.
Anti-spam verification:
If you are a human please identify the position of the character covered by the symbol $\varnothing$ in the following word:
p$\hbar$ysicsOve$\varnothing$flow
Then drag the red bullet below over the corresponding character of our banner. When you drop it there, the bullet changes to green (on slow internet connections after a few seconds).
Please complete the anti-spam verification




user contributions licensed under cc by-sa 3.0 with attribution required

Your rights
...