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53
Text 7
SCIENCE, SPIRITUALITY, AND SOME MISMATCHED SOCKS
Part 2
Other scientists have gotten a more direct look at the particles' secret behavior.
They pulled off this feat by resolving something called Hardy's paradox, which
basically addressed one of the trickiest aspects of quantum physics: by observing a
particle you might affect its property.
In 1990, the English physicist Lucien Hardy devised a thought experiment. The
common view was that when a particle met its antiparticle, the pair destroyed each
other in an explosion. But Mr. Hardy noted that in some cases when the particles'
interaction wasn't observed, they wouldn't annihilate each other. The paradox:
Because the interaction had to remain unseen, it couldn't be confirmed.
In a striking achievement, scientists from Osaka University have resolved the
paradox. They used extremely weak measurements -- the equivalent of a sidelong
glance, as it were -- that didn't disturb the photons' state. By doing the experiment
multiple times and pooling those weak measurements, they got enough good data to
show that the particles didn't annihilate. The conclusion: When the particles weren't
observed, they behaved differently.
In a paper published in the New Journal of Physics, the Japanese team
acknowledged that their result was "preposterous." Yet, they noted, it "gives us new
insights into the spooky nature of quantum mechanics." A team from the University
of Toronto published similar results some months later.
Some researchers are using the uncertain state of photons to solve real-world
problems. When encrypting sensitive data such as a bank transfer, both the sending
party and the receiving party must have the same key. The sender needs the key to
hide the message and the receiver to reveal it. Since it isn't always practical to
exchange keys in person, the key must be sent electronically, too. This means the key
(and the messages) may be intercepted and read by an eavesdropper.
An electronic key is usually written in the computer binary code of "ones" and
"zeros." Quantum physics permits a more sophisticated approach. The same "ones"
and "zeros" can now be encoded by using the properties of photons, like spin. If
someone intercepts a photon-based message, the spins change. The receiver then
knows the key has been compromised.
MagiQ Technologies Inc. of Cambridge, Mass., refreshes its quantum keys as
often as 100 times a second during a transmission, making it extremely hard to break.
It sells its technology to banks and companies. Dr. Gisin is a founder of ID Quantique
SA in Switzerland. The company's similar encryption tool is used by online lottery
and poker firms to safely communicate winning numbers and winning hands. Votes
cast in a recent Swiss federal election were sent in a similar way.
Because of its bizarre implications, quantum theory has been used to
investigate everything from free will and the paranormal to the enigma of
consciousness. Several serious physicists have devoted their lives to the study of such
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