By GAUTAM NAIK
One of quantum physics' crazier notions is that two particles seem to communicate with each other instantly, even when they're billions of miles apart. Albert Einstein, arguing that nothing travels faster than light, dismissed this as impossible "spooky action at a distance."
The great man may have been wrong. A series of recent mind-bending laboratory experiments has given scientists an unprecedented peek behind the quantum veil, confirming that this realm is as mysterious as imagined.
Quantum physics is the study of the very small -- atoms, photons and other particles. Unlike the cause-and-effect of our everyday physical world, subatomic particles defy common sense and behave in wacky ways. That includes the fact that a photon, which is a particle of light, exists in a haze of multiple behaviors. They spin in many ways, such as "up" or "down," at the same time. Even trickier, it's only when you take a peek -- by measuring it -- that the photon fixes into a particular state of spin.
Stranger still is entanglement. When two photons get "entangled" they behave like a joint entity. Even when they're miles apart, if the spin of one particle is changed, the spin of the other instantly changes, too. This direct influence of one object on another distant one is called non-locality.
These peculiar properties have already been proven in a lab and tapped to improve data encryption. They could also one day be used to build much faster computers. Some philosophers see quantum phenomena as a sign of far greater unknown forces at work and it bolsters their view that a spiritual dimension exists.
"We don't know how nature manages to produce spooky behavior," says Nicolas Gisin, a scientist at Geneva University, who led a recent experiment demonstrating action-at-a-distance. "But it's a fascinating time for physics because it can be mastered and exploited."
Einstein refused to believe that a photon could be in all states at once and set out to find an explanation for their seemingly odd behavior. God doesn't play dice with the universe, he said at the time. Danish physicist Neils Bohr, a big proponent of quantum uncertainty, shot back: "Quit telling God what to do."
Trying to poke holes in the notion of spooky action at a distance, Einstein and two colleagues published a paper in 1935 that appeared to demonstrate the existence of mysterious "hidden variables" and show that quantum theory was incomplete. In a seminal 1964 paper, Irish physicist John Bell raised questions about the mathematical validity of Einstein's work.