Question:
Recently I heard about quantum tunneling. I heard it is the reason why the sun can turn hydrogen into helium, even if the required temperature for this fusion is not reached. But how exactly does this work? How can particles "borrow" energy to fuse, and then release this energy again? I understand the "mountain-metaphor" in which the particle has to 'climb' up the mountain, and then 'roll' down again, but how does this work on the scale of particles? Does it have to do something with the particle-wave duality?
Replies:
Ruben,
Single particles at the level of quantum physics do not behave according to what some call ?common sense?. What we see from day to day is only an average effect of millions of particles together. One uncertainty principle involves energy and time. Overall, energy is conserved. For extremely short lengths of time, energy can go out of balance. Energy shift multiplied by the time over which the shift exists has to be on the order of 10^-34 Joule-seconds or less. In day to day life, this is too small to have any noticeable effect. Within a single atom, this is enough to allow tunneling.
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