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Imagine throwing a handful of pebbles lightly at a window, and most of them
bounced back, just as you expect, but a few of them disappeared on this side
of the glass and reappeared on the other side of the window without breaking
the glass. Welcome to the Tunnel effect in the surreal world of quantum
physics where the pebbles are smaller than atoms.
The reason this can happen has to do with the fact that light, electricity
and all matter and energy have a wave nature as well as a particle nature,
and its the wave nature that describes the likelihood of an electron or
photon actually being located "there", or "there".
Electrons, protons and photons have been seen to "tunnel" through an
When two quantum particles, such as two protons, come close to one another,
but do not actually touch, the uncertainty in their positions allows their
quantum waves to overlap to some extent. As a result, they may "tunnel
through" the gap between them, and interact. This is exactly what happens
inside the Sun and stars -- protons which are kept at a distance from one
another by the repulsion of their positive charge can still fuse together
because of tunneling. And that nuclear fusion is what keeps the interior of
the Sun hot, and makes its surface shine. Without tunneling, we would not be
In modern electronics tunnel diodes take an electron from here and put it
there without allowing it to occupy the intervening space, or as the
textbooks drily put it, "the penetration of the wave function into the
classically forbidden region." Scanning tunneling electron microscopes work
on this principle. An electric field applied to a metal tip so that the
electrons in the tip have enough energy to reach a metal surface underneath
for a short distance. However the electrons cannot exist in the vacuum
between the tip and the surface. A small current results from the electrons
tunneling out of the tip, teleporting from the tip to the surface. No
electron can be detected between the tip and the surface.
The electron "pebble" on this side of the barrier has a tiny chance that it
could also be a metre to the left, ten centimetres upwards, or even on the
other side of the barrier. So when you send lots of low energy electrons or
photons against a barrier, a small fraction of them appear on the other
This kind of disappearing and re-appearing act happens all the time within
individual atoms. Electrons orbit an atomic nucleus in shells of different
sizes and distances, sort of like a planet orbiting the sun, but where the
planet is smeared out into a ball around the sun. The electrons can move
nearer or closer or further away from the nucleus as they gain or lose
energy, say by absorbing or emitting light. However, the electrons are not
allowed to be between these shells. The space between orbits is a forbidden
zone. So how do electrons make the jump from an inner orbit to an outer
orbit if they're not allowed to travel the space in between - the
no-mans-land Pauli exculsion zone? The answer is that they use the tunnel
effect. They disappear from their old orbit and reappear in the new orbit,
without the bother of actually moving through the space in-between. It kind
of puts old Captain Kirk to shame.
This is what I'd call REAL teleportation. Captain Kirk had the kind of
teleportation being researched in the labs of the University of Wales, IBM
laboratories, and many other institutions. Its a major factor in unbreakable
quantum cryptography. Briefly you convert the original Kirk into a coded
signal, killing him in the process. You then send this file by radio or by
post, or by wire to the receiver, where Kirk is resurrected - destroying his
file in the process. You'd never get me travelling on one of the damn
things! And of course, the maximum speed is lightspeed.
How fast does a photon or electron tunnel? How much time between when it
disappears is there before it reappears? Gunter Nintz of the University of
Cologne decided to find out, and performed the experiment in 1996 . He was
unlucky enough to have an article about the results of his work published in
New Scientist in their April 1st issue. So controversial were his results
that many readers chose to believe it was an April fool's joke pulled by the
magazine, despite the denials of the editors. But it was no joke. Dr Nintz
had shown that the tunnel effect was faster than light.
He sent a microwave signal through a path where it was split by an
electronic mirror into two beams. One beam travelled through the air at the
speed of light. The other half was directed at a barrier, which should have
stopped the signal cold. Sensors at the other end displayed on an
oscilloscope. What they showed where two peaks, one in front of the other,
one for each beam. The beam from the photons that had tunnelled past the
barrier arrived five times faster than the beam of light through air. Nintz
had sent a signal faster than light.
Naturally this was an unpopular result, and Raymond Chaio reproduced the
experiment and also got a signal faster than light. Chaio was unhappy with
the idea of information going faster than light, but he had a problem in
that the definition of information at the quantum level has always been
vague. He stated that no information could be sent faster than light, just
random noise. The solution of the majority of the scientific world was to
redfine the word "signal" so as to not include the experimental results.
There was much handwaving about "signal fronts", "carrier waves" , and
Nintz's response was to sens an unpopular result, and Raymond Chaio
reproduced the experiment and also got a signal faster than light. Chaio was
unhappy with the idea of information going faster than light, but he had a
problem in that the definition of information at the quantum level has
always been vague. He stated that no information could be sent faster than
light, just random noise. The solution of the majority of the scientific
world was to redfine the word "signal" so as to not include the experimental
results. There was much handwaving about "signal fronts", "carrier waves" ,
and other jargon.
Nintz's response was to send Mozart's 40th symphony through the barrier. It
got through and arrived faster than light. Chaio and his colleagues still
refused to accept that this meant that information had travelled faster than
The reason that the physics community is unhappy with messages going faster
than light, is that Relativity predicts that an observer in a different
frame or reference, one moving at a different acceleration, may see the
message arrive before it was sent, which has been interpreted as meaning
that cause and effect would be violated. This would be very bad! However,
perhaps things aren't as bad as they seem.
Lets revisit relativity and why travelling faster than light is connected to
time running backwards, and see if its really what would happen.
If light is bounced off the face of a clock, and travels out in a straight
Now if you follow one of the photons, and therefore travel at the speed of
light, when you look back, you will always see the same time. It will seem
as if time is standing still.
If you travel away from the clock faster than the photon that carries the
5pm information, then you will encounter earlier photons that show earlier
information, and it will look to you as if the clock is winding backwards.
This is in all the textbook explanations as an example of moving backwards
in time, when its obviously just the illusion of doing so.
Not documented in the textbooks, is that if you move towards the clock, you
will see more and more recent photons showing the clock face moving forward.
The faster you travel towards the clock, the faster time will seem to go -
it would appear as if you are travelling into the future much faster than
normal. So in this case faster than light travel gives you the illusion of
forward time travel.
Now this corresponds to what has happened in the case of Professor Nimtz and
his tunneling Mozart. Both the reciever and the transmitter are in the same
frame or reference, so there is no violation of cause and effect. Mozart
just gets to the receiver from the tunnelled beam faster than light from the
Einstein was thinking of light as Newtonion pebbles, when in fact they are
quantum probablistic pebbles that have a wave-like chance from moment to
moment of being absolutely anywhere in the Universe.