Free Quantum Theory Cannot Hurt You by Marcus Chown Page B

will tell us about some property of P. According to the Heisenberg uncertaintyprinciple, however, the measurement will inevitably involve us losing knowledge of some other property of P.
    But all is not lost. Because P* was entangled with A, it retains knowledge about A. And because A was entangled with P, it retains knowledge about P. This means that P*, though it has never been in touch with P, nevertheless knows its secrets. Furthermore, when the measurement was made on A and P together and information about some property of P seemed to be lost, instantaneously it became available to A’s partner, P*. This is the miracle of entanglement.
    Since we already know about the other properties of P, obtained from A, we now have all we need to make sure P* has exactly the attributes of P. 3 Thus we have exploited entanglement to circumvent the restrictions of the Heisenberg uncertainty principle.
    The amazing thing is that, although we have exploited entanglement to make a particle P* with the exact properties of P, at no time did we ever possess any information about the missing property of P! It was transmitted out of our sight through the ghostly connections of entanglement. 4
    Calling this scheme teleportation is a bit of a cheeky exaggeration since it solves only one of the many problems in making a Star Trek transporter. The researchers of course knew this. But they also knew a thing or two about how to grab newspaper headlines!
    As it happens, the Achilles’ heel of the Star Trek transporter turns out to be neither pinning down the position, and so on, of every atomin a person’s body nor assembling a copy of the person from that information. It’s actually transmitting the sheer volume of information needed to describe a person across space. Billions of times more information is needed than for the reconstruction of a two-dimensional TV image. The obvious way to send the information is as a series of binary “bits”—dots and dashes. If the information is to be sent in a reasonable time, the pulses must obviously be short. But ultrashort pulses are possible only with ultrahigh-energy light. As science fiction writer Arthur C. Clarke has pointed out, beaming up Captain Kirk could easily take more energy than there is in a small galaxy of stars!
    Teleportation and nonlocality aside, the most mind-blowing consequence of entanglement is what it means for the Universe as a whole. At one time, all particles in the Universe were in the same state because all particles were together in the Big Bang. Consequently, all particles in the Universe are to some extent entangled with each other.
    There is a ghostly web of quantum connections crisscrossing the Universe and coupling you and me to every last bit of matter in the most distant galaxy. We live in a telepathic universe. What this actually means physicists have not yet figured out.
    Entanglement may also help explain the outstanding question posed by quantum theory: Where does the everyday world come from?
WHERE DOES THE EVERYDAY WORLD COME FROM?
    According to quantum theory, weird superpositions of states are not only possible but guaranteed. An atom can be in many places at once or do many things at once. It is the interference between these possibilities that leads directly to many of the bizarre phenomena observed in the microscopic world. But why is it that, when large numbers of atoms club together to form everyday objects, those objects never display quantum behaviour? For instance, trees never behave as ifthey are in two places at once and no animal behaves as if it is a combination of a frog and a giraffe.
    The first attempt to explain the conundrum was made in Copenhagen in the 1920s by quantum pioneer Niels Bohr. The Copenhagen Interpretation, in effect, divides the Universe into two domains, ruled by different laws. On the one hand, there is the domain of the very small, which is ruled by quantum theory, and on the other there is the domain of the very big,