How does quantum tunneling occur?
Quantum tunneling is the possibility of detecting a particle beyond an energy barrier it could not cross classically.
Physical mechanism and core principles
A wavefunction does not instantly become zero at a finite barrier; it decays inside and may retain a small amplitude beyond it. Probability is highly sensitive to barrier height, width and particle energy.
Evidence, applications and limits
Tunneling contributes to alpha decay, stellar fusion and scanning tunneling microscopy. It does not violate energy conservation or transmit chosen information faster than light. Quantitative interpretation must state boundary conditions, units and ideal-model assumptions.
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