Originally posted by yak.h'cir
You could try to write quantum physics off as something obscure, that could never effect the world we see around us.
Its the most accurate (ie squares up with experimental results) model of the universe we've (humans) have ever made. Predictions for the behaviour of systems of particles are in agreement with experiments down to 10 decimal places. Newton's Gravity screws up at about the 4th decimal place.
Its got little to do with common sense too. Even some of the "basic" ideas aren't what most people would think of as correct. In Quantum Mechanics ab != ba. Its non-commutative algebra.
With "usual" numbers you get things like 3x5 = 5x3. No problem. Once you meet matrices you realise that not everything is so nice. Quantum Mechanics is based on such "non-nice" things.
Originally posted by Grrrrr
Could you please, not entirely relevant to the thread but i've seen it done before and cant quite remember the steps...
It's quite similar to the x=0.9r , 10x = 9.9r , etc etc etc proof IIRC
Suppose a number is K = 0.ABC.....XYZABC.....XYZABC.....XYZ...... etc
Where A,B,C, X, Y, Z are single digits, ie 1/7 = 0.142857142857.... so A = 1, B = 4 etc
There are "n" digits before repetition begins.
K = 0.ABC.....XYZABC.....XYZABC.....XYZ......
K * 10^n = ABC......XYZ
.ABC......XYZABC.......
(K * 10^n) - K = ABC......XYZ (a whole number)
K (10^n - 1) = ABC......XYZ
K = (ABC......XYZ)/(10^n - 1)
Since K is a repeated decimal, n is not infinite, therefore 10^n - 1 is not infinite either, thus ABC.....XYZ/(10^n - 1) is a finite integer over another finite integer, otherwise known as a rational number
I apologise if is appears crud, as I've said before, forum text is crap for maths symbols and explainations