Mathematically expressed as:

_ h dx dp >= - 2

*(Okay, yeah, this is supposed to say
"delta-x times delta-p is greater than or equal to
h-bar over 2", but trying to express mathematical
formulae in HTML sucks eggs. I can't wait
until Mozilla or something learns how to grok
MathML. Or TeX.)*

h-bar is Planck's constant

Essentially what this means is that the more precisely you know something's position (x), the less you know about that object's momentum (p) and vice versa.

There's a nice web page about the Heisenberg Uncertainty Principle at

`http://tardis.svsu.edu/~slaven/uncertainty/uncertainty7.html`