This piece of Physics is one of my favorites from this year because it is a bizarre concept that I would gradually grow to understand and then suddenly be like, wait that's crazy! But I did an experiment using the theory in a lab session so I have seen proof but then again it goes against everything I see around me. This is probably one of the hardest things I learnt this year and I haven't really done the explainy thing for a while so you'll have to bear with me.
The concept is quantum tunneling. To understand this we need to look at things on a nano scale. At this level the laws of Physics are very different to things at the size that we are used to. But things that happen on a tiny level affect what we can see at the size of us and at the size of galaxies.
Take an electron at the surface of a material. An electron is a fundamental particle and so is one of the smallest things we know. This electron can move freely in any conducting material like metal but cannot move through insulating material like air. So a layer of air will act as a barrier preventing movement through it. In our everyday life you know that you can cross a barrier such as a wall or hill but it takes energy to get over it. And now I'm going to tell you that it's different for an electron, an electron doesn't have to have enough energy to cross the barrier, it can tunnel through it. But that phrase is kind of misleading, the electron doesn't dig through the barrier it just is there.
You can explain this with wave functions and probabilities but that is even stranger conceptually. That relies on wave particle duality which still makes my head spin so we'll just focus on this for now I think.
Actually this phenomena is how fusion occurs in the Sun. In the Sun protons are combined to create larger elements and lots of energy but it takes energy to get two protons over a barrier and close enough to combine, the kind of energy the Sun just doesn't have. The protons tunnel together.
So an electron can appear on the other side of a barrier with the same amount of energy it had on the other side and we know this is true because of a method called Scanning Tunnel Microscopy (STM) which uses quantum tunneling to make images of atoms. The smaller the width of a barrier the easier it is for an electron to pass the barrier. The flow of electrons is the definition of an electron current and so the current passing through a gap of air indicates how wide that gap is. A probe passes over a surface tracking this current and a computer maps out the height of the surface and it is at such a small scale that what you see are the atoms that make up the surface. Pretty cool huh? It gets even cooler when you then use a probe to move an atom across a surface and then you are building crystals with whatever properties you want or storing unimaginable amounts of data on tiny chips. That's how they made this movie which is the smallest motion picture ever made:
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