When you heard the word ‘quantum mechanics’, a lot of things come to your mind like cat being alive and dead at the same time, nothing is precisely known, etc. While the above idea is somewhat linked to quantum mechanics, they are not what quantum mechanics is about.
To understand what quantum mechanics is about, let’s start with the meaning of the words itself. ‘Quantum’ means quanta or discrete quantity of something. Here is an example. In an ocean, water is everywhere but the smallest bit is the water molecule (H20). And ‘mechanics’ means the study of motion and behaviour of something. So quantum mechanics is about studying the properties and behaviour of the smallest bit or discrete quantity of something. It is like studying the properties and behaviour of H2O molecule for the ocean. In real life, we study about the discrete quantity of the whole universe like atoms, electrons, protons, quarks, etc.
The first important concept that physicists learn when they study quantum mechanics is the wave function. The wave function is perhaps the most useful and important function in quantum mechanics. It contains all the information we can possibly extract from quantum system.
The square of wave function gives the the probability of finding a particle in that region of space. Although we have known and studied the wave function for about a century and perhaps use it for many of our calculations, no one up to this day knows the physical meaning of wave function. Yeah! Yeah! We have used it to know the probabilities of finding a particle, etc but we don’t what physical meaning does the wave function convey.
Now, here is a quick summary. Quantum mechanics is about the study of the properties and behaviour of the discrete quantity of something. And for the wave function, don’t you want to be the person who figures out the physical meaning of wave function. I’m sure you are up for this challenge.
Knowledge Glutton 
First of all, Quantum Mechanics is about studying
the properties and “mechanical” behaviour the smallest
discrete particle – Planck’s “quantum of action” (h).
Secondly, it needs to understand the first point.
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One word: time. To separate cause from just an effect of that cause we use a clock. If the clock ticks too slowly then it becomes impossible to separate cause and effect (c&e). Time is non reversible BECAUSE cause c&e is non reversible. If c&e were reversible then we have mathematics but no science.
Attempting to measure c&e with a clock that is too slow provides the false observation that they were instantaneous IOW in ‘superposition’: in both states at the same time. In this unhappy situation statistics can indeed be used to provide accurate probability predictions but however, providing no information as to what is going on in reality.
It would seem our fastest atomic clocks are way, way too slow to separate c&e in the quantum world. Also, just to observe anything you have to throw something at it and wait for it to bounce back and then understand the pattern. Thus all observations, without exception, are in the past. In the macro world clock ticks are mostly fast enough to separate c&e. Observation via throwing the smallest ring we have at macro objects isn’t much of a problem either since light reflects at c appearing almost instantaneous and mostly, only very slightly heating up what we are observing. In the quantum world observation presents an enormous problem since we only have tiny things to throw at other tiny things. So just observing anything in the quantum world has a major impact on what is being observed. It’s no wonder that just observing causes a ‘collapse of the wave function’ to a particle. Because all observations are in the past and c&e is so very, very fast at the quantum level what we end up seeing is too far into the past.
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Do you guys have a spell checker? Put a little effort into your work.
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Sorry, I will be careful next time.
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