Science Questions and Answers

Start Your Free Trial

According to the Heisenberg uncertainty principle, if the position of a moving particle is known, what other quantity CANNOT be known?

Expert Answers info

Lupe Tanner, Ph.D. eNotes educator | Certified Educator

briefcaseCollege Professor

bookPh.D. from Oregon State University

calendarEducator since 2015

write3,395 answers

starTop subjects are Science, Math, and Business

Heisenberg's Uncertainty principle states that both the location (or position) and momentum of a particle can not be simultaneously ascertained accurately. The more accurately we try to measure one of these quantities, the less accuracy we will achieve in the measurement of the second quantity. The principle can be mathematically stated as:

`Deltax Deltap > h/2pi`

where, `Deltax`  is the uncertainty in the measurement of position , `Deltap`  is the uncertainty in the measurement of momentum and h is the Planck's Constant. 

This is of the principal concepts of quantum mechanics. Since the value of Planck's constant is small (`6.626 xx 10^(-34)`), this principle has meaning only for very very small particles. At large scales, the uncertainty in measurements would be relatively insignificant, and unlikely to be even noticed. 

Hope this helps. 

check Approved by eNotes Editorial