Question about the double slit experiment 2 I had wondered if anyone has ever tried doing the experiment with molecules, then I came across this webpage ( http://www.livescience.com/19268-quantum-double-slit-experiment-largest-molecules.html ). These researchers used 58 to 114 atom molecules, made up of carbon, hydrogen and nitrogen, and got the same results; getting an interference pattern. Now, I am wondering as to what limit can you go before this 'state of uncertainty' no longer works? If a water molecule had this affect, how big can you make the molecule until it no longer will produce the interference pattern and will it work once the molecule becomes an element or even a compond (is it the actual size or mass that's the factor?), I mean 114 mixed atom molecules seemed alot, what number of H2O molecules is needed before it no longer works and frankly, what number of H2O molecules is needed to classify it a compond? Because I can't help but think that 70% of my body mass is in this 'state of uncertainty'...lol
 A: In principle there is no limit; in practice it becomes harder and harder to measure the effect as the wavelength decreases as the mass increases. Once the fringe spacing becomes small compared to the size of the molecule, it becomes almost impossible to see the fringes; similarly as the molecules get larger, the slits have to be larger to let them through; this will further blur the pattern.
But just because you can't see it doesn't mean it's not there...
A: After Einstein proposed a quantum theory of light that settled the controversy over whether light was a wave or a particle, physicists wondered if wave/particle duality could apply to matter as well as to photons.  The de Broglie hypothesis proposes that matter also possesses a wave/particle dual nature.  The simplest form of De Broglie's equation relates Planck's constant to a particle's momentum in order to derive its wavelength:
Lambda = h / p, where lambda is wavelength, h is Planck's constant, and p is momentum
He used momentum rather than energy because it wasn't clear whether kinetic energy should be included in the total, or alternatively if total relativistic energy should be used.
There is no reason why the de Broglie wavelength should not be applied to any matter, regardless of scale.  However the more massive the object, the greater its momentum, and the smaller its wavelength.  Macro scale objects would have very tiny wavelengths and, as Floris points out in his answer, there are great obstacles to measuring these wavelengths.
Your body is not in a meaningful state of uncertainty, because all the quanta of which it is made are entangled with each other and with the world you inhabit.  Their wave functions generally are in a state of quantum decoherence, so your body is described by classical mechanics, which does not account for quantum uncertainty. 
