NARRATOR: In this experiment, Guenter Nimtz splits a microwave signal in two. Half goes through the air, traveling at the speed of light, and half is fired into a barrier to block the signal. But that's not what happens.
GUENTER NIMTZ: This is the oscilloscope where you see the signal and then we can see which one is faster.
NARRATOR: The two humps on the screen are not in the same place because the microwaves that went through the barrier got to the detector first - apparently exceeding the speed of light.
GUENTER NIMTZ: Only a very small part comes to the other side, but it comes and this part comes at the velocity which is much faster than the velocity of light.
NARRATOR: So how could the microwaves go faster than light - and what was the role of the barrier? Nimtz chalks it up to a strange phenomenon called quantum tunneling. At the subatomic or quantum level, the world is ruled by probability and chance, and the seemingly impossible occurs all the time. For example, when a stream of particles like photons meets a barrier, most bounce off. But a few of them materialize on the far side of the barrier and continue on their way. Nimtz detected the particles that appeared, and measured how fast they got there.
GUENTER NIMTZ: And the news about this we did this for fun, and when we figured out that it's faster than the velocity of light we did not think about its importance.
NARRATOR: Another expert in quantum tunneling is Raymond Chiao. He agrees with at least part of what Nimtz has found.
RAYMOND CHIAO: In our experiments we have measured that a single photon can tunnel across a tunnel barrier at 1.7 times the speed of light.
NARRATOR: What bothers Chiao is not that random photons seem to go beyond the speed of light, but that Nimtz claims he can use tunneling to send information faster than light.
RAYMOND CHIAO: To have a genuine signal you really have to control the signal, but in, in quantum mechanical tunneling it's a completely random process. Fundamentally we cannot, we cannot send information with this tunneling particle.
GUENTER NIMTZ: Yeah, some colleagues are claiming that you cannot send information and then we started to transmit Mozart 40 and this is for instance the original tape. That's what we sent at a speed of 4.7 times the velocity of light and a distance of about 14 centimeters, whether you can recognize Mozart 40 or not.
NARRATOR: Despite the randomness and uncertainty of the tunneling process, Mozart seems to have gone through the barrier.