Not everything in this universe is as we see.
We are all familiar with the wave nature of the particle. In fact, the most intriguing part of the quantum mechanics is that, in practically every quantum experiment, our main part is to learn how to not look at the system. Because when we look at the particle, its wave function collapses and its outcome alters. It will alter the results when observed and that would be exactly what we anticipate in the classical world.
One of the most mind-blowing quantum phenomena is that of tunneling effect.
Think about passing straight through the walls without even having to use the door or an alternate path, however, that would sound crazy to humans normally in light of the fact that our comprehension of the world as a human doesn’t allow peculiar events like these yet that doesn’t generally mean they don’t exist.
Now think of a person standing on the road, although your eyes tell you that person is at one specific location but in reality, he literally could be anywhere in the universe. And that is because of the wave nature of the particles as we all are familiar that a wave is never at a single point rather it is spread everywhere and there exists a corresponding range of probabilities that is also known as matter wave, described by the wave function ψ or Ψ (called psi), that really enables us to determine all the possible positions a particle can occupy.
But keep in mind that these effects are only visible at the subatomic level.
Give us now a chance to discuss what precisely is quantum tunneling effect.
So, what is it?
Basically, at the subatomic scale, the quantum physics takes over the classical physics and wave nature of a particle overwhelms and the particle doesn’t really have to take the longer route to go to the other side of the wall rather it simply can penetrate through it and this penetration is what we called quantum tunneling. Particle wave functions can leak across the barrier.
This is not only hypothetical, rather it happens all the time around us.
Radioactive decay, diodes and resistor and even numerous biological processes like enzymes in our body use tunneling effect to execute certain tasks.