delta y delta p_x  =  0 ........... can this be true depending on the mass of the particle ( i.e for a massless particle ) ?

UNCERTAINTY PRINCIPLE

In quantum mechanics, the Heisenberg uncertainty principle states that certain pairs of physical properties, like position and momentum, cannot simultaneously be known to arbitrary precision.

(delta x) . (delta p) > h / 4 pi

or, (delta x) . (m) (delta v) > h / 4 pi

or, (delta x) . (delta v) > h / 4 m pi

So, for a massless particle, say photon, m = 0

So, (delta x) . (delta v) > infinity

@sahell, photon is massless.

@canorous i hope you have got the point.

Nudge me if you still have any doubt regarding this.

but we claculate mass of photon dont we by de brogale equation