Question

2. Describe the basic principles of quantum physics. 3. Compare and contrast Newtonian and quantum physics principles as you see them in people's environments and health-care settings.

Answer 1

The basic principles of quantum Physics:

We know in classical mechanics we can determine all physical information related to a system just by two fundamental quantities its position r(t) and its momentum p(t) at any time t. But in quantum mechanics according to Heisenberg's principle we can't determine the exact position and momentum of a system therefore we can't get any physical information about the system.

So to interpret all the physical information of a system or particle certain postulates has been formalised known as basic principles of quantum Physics. These are

State of a system

State of a system at any time t is specified by a state wave function Ψ. This state function Ψ has all the information about the system. While Ψ itself has no physical interpretation but |Ψ|² called probability density have.

Observables

Any physically measurable quantity is called observable. And Every observable in quantum Physics is represented by linear hermitian operator.

Like for momentum and energy there are hermitian operators.

Measurement and eigenvalue

In any measurement of an observable A associated with operator $\hat A$ the only possible value are one of eigen value $a_n$ which satisfies the condition

$\hat A\Psi_n=a_n\Psi_n$

Probability of outcome of measurement

The probability to get an eigenvalue a_{​​​​​​n} is given by

$P_n(a_n)=\frac{<\Psi_n|\Psi>}{<\Psi|\Psi>}$

Time evolution of a system

The wave function of a system evolve in time according to Schroedinger's time dependent equation

$i\hbar\frac{\partial\Psi}{\partial t}=\hat H\Psi$

these are the fundamental principles of quantum Physics.