# Did photon obey Uncertainity Principle?

1. Jul 23, 2009

### sndtam

Photon has no mass.So when we apply Uncertainity principle to photon
position*velocity*mass=greater than plancks constant
So when we use mass as null,the equation implies that 0<h.
That is h is negative.But h is positive.
Please explain me this.

2. Jul 23, 2009

### xepma

The uncertainty relation follows from the commutation relation of the momentum and position operators. The photon does not carry a mass, but it does carry a momentum.

3. Jul 23, 2009

### humanino

This is not momentum. This is an approximation of momentum at low velocity. The correct dispersion relations for the massless particles as the photon is
$E=pc=\hbar\omega=\hbar c k$

Last edited: Jul 23, 2009
4. Jul 23, 2009

### ZapperZ

Staff Emeritus
The single-slit diffraction phenomenon is the clearest example of photons "obeying" the HUP.

Zz.

5. Jul 23, 2009

### sndtam

Thank you

6. Jul 23, 2009

### Naty1

As far as we know, everything obeys quantum principles...including HUP...

7. Jul 23, 2009

### maverick_starstrider

I refuse to obey your quantum principles ;)

8. Jul 23, 2009

### sndtam

Thanks a lot

9. Jul 24, 2009

### scott.ager

A smart dope is in direct violation of my HUP.

- Werner

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