# Double slit ?

1. May 7, 2010

### cragar

If photon's cannot couple with other photons , then when we shoot photons through a double slit and we get an interference pattern , How are the photons interfering with the other photons , and if there is no such thing as half photon like the photon is either absorbed or it is not , then how is the localized energy of the photon interfering with the slit , Or if we shoot them one at a time will still get the inference pattern , To Quote Paul Dirac "The photon then interferes with itself " I hesitated to post this.

2. May 7, 2010

### Livect

All matter exhibits both wavelike and particle-like properties, so one can't simply imagine firing a photon like one hits a golf ball. In fact, photons are one of the prime examples of wave-particle duality.

It's actually one of the central topics of quantum mechanics, and I suggest a textbook to completely get a grasp of it.

I think this thread is what you're looking for:

3. May 7, 2010

### barna

you could try reading feynman lecture series vol 3, it explains the wave particle duality in the context of double slit experiment and how it leads to the heisenberg's uncertainity principle...it is indeed the foundation of q mech....without heisenberg's uncertainity quantum mechanics would be meaningless!

4. May 7, 2010

### cragar

okay thanks for the answers , when we fire one photon at a time is it a double slit pattern or do we get a mixture of a single slit and double slit pattern .

5. May 7, 2010

### cesiumfrog

You needn't have hesitated.
Exactly, it is.

6. May 7, 2010

### barna

in a double slit set up, firing one photon at a time would lead to a double slit pattern..however if one tries to detect through which slit each photon passes one looses the double slit pattern...the resulting pattern in the latter case is mererly the addition of the intesities I1 and I2 from each of the slits. without the phase factor...this is the alternative statement to uncertainity principle.....the very act of measurement disturbs the system and causes the uncertainity! reading feynamn will make it clearer !