I am trying to solve this question," Why electrons can't remain inside the nucleus?"I am trying to mention three points here-
1.Nuclear size
2.Nuclear spin
3.Nuclear magnetic moment
For the third part,I think I am pretty clear about it since the magnetic moment of electron is 1836 times greater than that of proton,but I am trying to explain the first and the second part.
For the first part I want to mention the Heisenberg's relation,but I am confused about this relation because different books have given me different relation.So please give the actual relation.

I dont know how to write Greek letters and symbols on this so...
the heisenberg uncertainty principle is: (delta)x (delta)p is greater or equal to h-bar/2
There are a few uncertainty principles but heisenbergs is about position and momentum so you might be finding different uncertainty principles in your text book.
All uncertainty principles are based on the generalized uncertainty principle which is: <|[P,Q]|> which is not equal to 0.
The Heisenberg uncertainty princple is derived for this.
Hopes this helps