Question: give us a brief of quantum physics

Pierre Lasorak answered on 10 Nov 2014:

Hello
So Quantum Physics is the science of very small things, people started to get interested in it at the beginning of the 20th century. There is a lot to say but what I consider as a major result of quantum physics is what we call the wave-particle duality. That is to say, particle or even a bunch of particles, can behave either like billiard balls or like wave, and depending what experiment we make, we see different things that would appear completely inconsistent at first sight. Things like the particle passed through two holes in the mean time do happen in quantum mechanics and therefore in the real world.
If we continue on to this formalism, we get to what we call the Heisenberg uncertainty principle, which states that it it impossible to determine with infinite precision the place and velocity of a particle in the mean time. Of course this effect gets very small at our “human” sizes, which is why we can do it for a football, for example.
There are some other funny things going on at these scales, for example something called the tunnel effect: one illustration is the following: Take a 4 years old kid throwing a ball against a wall of 2 metres. You can assume that he will never have enough energy that he won’t ever be able to throw the ball on the other side of it. So in the real world the ball on the other side will never happen. In quantum mechanics this can happen, and in fact this is used in a lot of applications like for the ship in a phone or computer… In another sense you can calculate the chance of you crossing a concrete wall, and this will turn out to be possible. The only thing is that the chances are so small (and I mean small like one chance over billions of billions of billions) that we can just say in normal life it is impossible!
There is way more to discuss about QM…