OK, now I'm considering this problem with more information. Suppose you construct two beams of entangled particles that travel in opposite directions at or near light speed. At two very distant places where each beam is aimed, you have a double slit experiment at the end of each beam. Measuring just one of the entangled particles will collapse the wavefunction for both so that knowing the properties of one particle tells you the property of the other particle. So if covering one of the slits at the end of one beam will collapse the wavefunction at both ends, then will the double slit measurement at the other end show a fringe patern or not even though both slits are open at the other end? If so, then wouldn't this be a means of communicating instantaneously by chosing to cover one of the slits or not at one end?