The video explains the quantum mechanical phenomenon of tunneling, contrasting it with classical physics. In classical physics, an object encountering an impenetrable barrier will always reflect. However, in quantum mechanics, if a barrier is sufficiently thin, there's a probability that the object can pass through it. This is illustrated with the example of electrons passing through barriers. A practical analogy is presented using a glass of water. When the glass is held sideways, the fingers behind it are visible. When the glass is turned upright, the air layer between the glass and the surrounding environment acts as a reflective boundary, obscuring the view of the fingers. The speaker then demonstrates that by pressing the glass firmly, reducing the air layer to a minimum, the fingers become visible again. This is explained by photons from the finger quantumly tunneling through the thin air layer to reach the camera.

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In classical physics, if an object hits an impenetrable barrier, it will always bounce off of it. But in quantum mechanics, if the impenetrable barrier is thin enough, then the object has a non-zero probability of ending up on the other side. So, what that means is on a quantum scale, sometimes electrons can just go through stuff.

You can actually see a great analog of this using a glass of water. Notice that as I hold the glass sideways, you can see my fingers easily on the other side of the glass. But when I turn the glass upright, suddenly the sides of the glass become like a mirror; you can't see anything outside of it. So, in this case, the boundary is actually the air around the outside of the cup.

Now watch what happens if I press really hard and try to reduce that air layer in between my finger and the glass to as small as possible. It turns out that you actually can start seeing my finger. So, the photons from my finger can actually quantumly tunnel through that boundary layer of air and get to the camera.

Quantum Tunneling At Home

in classical physics if an object hits
an impenetrable barrier it will always
bounce off of it but in quantum
mechanics if the impenetrable barrier is
thin enough then the object has a
non-zero probability of ending up on the
other side so what that means is on a
quantum scale sometimes electrons can
just go through stuff
you can actually see a great analog of
this using a glass of water notice that
as i hold the glass sideways you can see
my fingers easily on the other side of
the glass but when i turn the glass
upright suddenly the sides of the glass
become like a mirror you can't see
anything outside of it so in this case
the boundary is actually the air around
the outside of the cup now watch what
happens if i press really hard and try
to reduce that air layer in between my
finger and the glass to as small as
possible
it turns out that you actually can start
seeing my finger so the photons from my
finger can actually quantumly tunnel
through that boundary layer of air and
get to the camera

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Quantum Tunneling At Home

Transcription