Since the beginning of the 20th century, quantum mechanics has revealed previously concealed aspects of events. Newtonian physics, taken in isolation rather than as an approximation to quantum mechanics, depicts a universe in which objects move in perfectly determinative ways. At human scale levels of interaction, Newtonian mechanics gives predictions that in many areas check out as completely perfectible, to the accuracy of measurement. Poorly designed and fabricated guns and ammunition scatter their shots rather widely around the center of a target, and better guns produce tighter patterns. Absolute knowledge of the forces accelerating a bullet should produce absolutely reliable predictions of its path, or so we thought. However knowledge is never absolute in practice and the equations of Newtonian mechanics can exhibit sensitive dependence on initial conditions, meaning small errors in knowledge of initial conditions can result arbitrarily large deviations from predicted behavior.
At atomic scales the paths of objects can only be predicted in a probabilistic way. The paths are not exactly specified in a full quantum description of the particles. The quantum development is at least as predictable as the classical motion, but it describes wave functions that cannot easily be expressed in ordinary language. In double-slit experiments, electrons fired singly through a double-slit apparatus at a distant screen do not arrive at a single point, nor do they arrive in a scattered pattern analogous to bullets fired by a fixed gun at a distant target. Instead, they arrive in varying concentrations at widely separated points, and the distribution of their hits can be calculated reliably. In that sense the behavior of the electrons in this apparatus is deterministic, but there is no way, without the ridiculously large body of knowledge that would allow a quantum description of the whole experiment, to predict where in the resulting interference pattern an individual electron will make its contribution.
Some people have argued that in addition to the conditions humans can observe and the rules they can deduce there are hidden factors or hidden variables that determine absolutely in which order electrons reach the screen. They argue that the course of the universe is absolutely determined, but that humans are screened from knowledge of the determinative factors. So, they say, it only appears that things proceed in a merely probabilistically determinative way. Actually, they proceed in an absolutely determinative way. Although matters are still subject to some measure of dispute, quantum mechanics makes statistical predictions that would be violated if some local hidden variables existed. There have been a number of experiments to verify those predictions, and so far they do not appear to be violated
) but yes, it is possible to send information faster than the speed of light using entangled particles. At least according to the latest Brian Greene book I read last year.
