Category Archives: Physics


If I ask a question ‘ how we can treat a particle at rest in quantum mechanics?’

What would be the answer .. u all knw ..

momentum of particle is zero . is it?

That’s great .

What ll be its consequence ?

Heisenberg uncertainty principle tells that

(uncertainty in momentum . uncertainty  in position) =h/4.pi uncertainty

and if momentum is going to zero then uncertainty  in position .. onnoo ‘ infinite ‘. 🙂

yes .. we know that particle is at rest , but don’t know where it is .

how amazing !!!



wooow .. how long the word is!!! no??

ya .. This word is  purely quantum mechanical .This word is never discussed in classical mechanics . Why ?

yeah !!! no two objects in macroscopic world is purely identical . You can label them.

one more thing happens in classical mechanics that is the concept of trajectory . you can track  the path of any classical particle , if you know its initial position , u may say after so much of time it will be at that position .

what about quantum mechanics .. correct .. there is no defined path or trajectory of any particle . one thing is that ‘what will be the probability to find the particle at any point’.

So , here comes the indistinguishable or identical particle . Every theory in quantum mechanics respects the indistinguishability .

If u see any two identical particle at their positions , after some time they move to different positions .u ll not able to say which particle is at which position because yes of course .. u r right .. they don’t have defined path .. just probability ..

What abt its state and Pauli’s Exclusion Principle ??

in next

….  continued