Take the 2-minute tour ×
Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free, no registration required.

marked as duplicate by Chris White, Qmechanic Apr 4 '13 at 16:06

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

2  
Possible duplicates: physics.stackexchange.com/q/24068/2451, physics.stackexchange.com/q/54184/2451 and links therein. –  Qmechanic Apr 3 '13 at 23:32
add comment

2 Answers 2

up vote 0 down vote accepted

I sense that the mathematical derivation of the uncertainty principle may not be a sufficient explanation... :) But if you're interested, look at the answer here: Heisenberg Uncertainty Principle scientific proof

Think about how we look at something in macro space - we shine a light on it, such as with a microscope, and see what reflects back. In the case of a very small particle, this light could be as small as one photon - but one photon has enough momentum to push the object we're examining when they collide. So if we want to know where a particle is in space, we bounce a photon off of it - but this accelerates the particle, so now its momentum is "uncertain" (or changed). Likewise if we want to know what its momentum is - now its position has changed.

Whatever technique is used to measure a quantity (photons are just an example), it necessarily has an impact on the subject of that measurement. Thus it is impossible to measure these quantities simultaneously to a degree of precision which exceeds the uncertainty principle's limitations.

share|improve this answer
2  
The uncertainty principle is much more than just the statement of the observer effect. –  Andrew Gibson Apr 4 '13 at 1:50
    
I know this question closed, however let me add a comment. If that measurement "would happen" the system would return reverse time to its past in order to "have it avoided"! It sounds crazy but so it would. –  al-Hwarizmi Jun 29 '13 at 14:35
add comment

You've probably heard the observational reason for the uncertainty principle which basically states that if you measure either position or momentum very accurately your measurement changes the other. That's a really nice hand-wavy explanation but the uncertainty principle is fundamental to waves and is not about measurement.

Check out the Wikipedia article on this. The second paragraph states:

[...] the uncertainty principle actually states a fundamental property of quantum systems, and is not a statement about the observational success of current technology

The article goes on to spell out in detail why this is so.

share|improve this answer
add comment

Not the answer you're looking for? Browse other questions tagged or ask your own question.