How is Schrodinger's cat dead and alive?

SCHRODINGER'S CAT is a thought experiment by Erwin Schrodinger to make the world understand that quantum particles exist in a superposition.

Quantum theory states that quantum particles can achieve more than one state simultaneously.

SCHRODINGER'S CAT EXPERIMENT:

If we put a cat in a strong box with a radioactive sample which has 50 per cent of chances of decaying and closes the box, it is very confusing for the observer outside to guess whether the cat is dead or alive after a period of time.   

         

So before opening the box, we can say that the cat is in superposition. That is it's in the state of both dead and alive. But if we open the box and observe we may find the cat in only one state that is the state of dead or alive.



This means that quantum particles exist in different states but when observed takes a single state.
And according to multiverse theory or many worlds theory, the universe achieves all the possible outcomes by splitting itself and making its copies. So from the thought experiment, we can say that the cat is alive and dead in the split universe. 
That means the quantum particles achieve all the possible positions one in each copy of the universe.


For further understanding :
https://www.aps.org/units/maspg/meetings/upload/franson-021815.pdf
https://www3.nd.edu/~jspeaks/courses/2007-8/20229/_HANDOUTS/quantum-mechanics.pdf

Physics tells us observations can't be predicted absolutely. Rather, there's a range of possible observations each with a different probability.     

Schrodinger Wave Equation explained in simple words

Newtonian Mechanics don't work in the quantum world.
Quantum objects are very microscopic that they can't be located but they can be probably located. And this probability can be determined by using wave functions of the quantum particles




Wave function gives us the probabilities of where the electron is likely to be. The act of not knowing where the electron is, allows its probability distribution to be spread out over a large space kind of wave. Therefore wave function is the function which describes the wave shape of the probability distribution of the electron.


The Heisenberg Uncertainty principle says that we can't predict the exact position and momentum of the quantum objects. But we can know about things like Energy levels and wave functions.
THE SCHRODINGERS WAVE EQUATION :

                                                                                                          = Wave function (psi)                    E= Energies of the electron is allowed to have 

E[(psi)(x)] = The energy levels of the wave function of the electron 

If we consider an electron inside a box where it is confined to only a few frequencies the wavefunction always needs to be 0. In other words, the electron has 0 probability to be found outside the box.

 

And we know the famous Einsteins equation  E=hf where h is Planks constant. Since only a few frequencies are allowed only certain energy levels are allowed.
That is what is meant by QUANTISATION.

Derivation :

For more detailed information :
http://physics.mq.edu.au/~jcresser/Phys201/LectureNotes/SchrodingerEqn.pdf
http://lejpt.academicdirect.org/A26/031_048.pdf

"No one undertakes research in physics with the intention of winning a prize. It is the joy of discovering something no one knew before."