One of the most surprising discoveries of modern physics is that objects aren't as separate as they may seem. When you drill down into the core of even the most solid-looking material, separateness dissolves. All that remains, like the smile of the Cheshire Cat from Alice in Wonderland, are relationships extending curiously throughout space and time. These connections were predicted by quantum theory and were called "spooky action at a distance" by Albert Einstein. One of the founders of quantum theory, Erwin Schrödinger, dubbed this peculiarity entanglement, saying "I would not call that one but rather the characteristic trait of quantum mechanics."
The deeper reality suggested by the existence of entanglement is so unlike the world of everyday experience that until recently, many physicists believed it was interesting only for abstract theoretical reasons. They accepted that the microscopic world of elementary particles could become curiously entangled, but those entangled states were assumed to be fleeting and have no practical consequences for the world as we experience it. That view is rapidly changing.
Scientists are now finding that there are ways in which the effects of microscopic entanglements "scale up" into our macroscopic world. Entangled connections between carefully prepared atomic-sized objects can persist over many miles. There are theoretical descriptions showing how tasks can be accomplished by entangled groups without the members of the group communicating with each other in any conventional way. Some scientists suggest that the remarkable degree of coherence displayed in living systems might depend in some fundamental way on quantum effects like entanglement. Others suggest that conscious awareness is caused or related in some important way to entangled particles in the brain. Some even propose that the entire universe is a single, self-entangled object.
What if these speculations are correct? What would human experience be like in such an interconnected universe? Would we occasionally have numinous feelings of connectedness with loved ones at a distance? Would such experiences evoke a feeling of awe that there's more to reality than common sense implies? Could "entangled minds" result in the experience of your hearing the telephone ring and somehow knowing - instantly - who's calling? If we did have such experiences, could they be due to real information that somehow bypassed the usual sensory channels, or are such reports mere delusions? Can psychic or "psi" experiences be studied by science, or are they beyond the reach of rational understanding?