# Stopped Light and the Heisenberg Uncertainty Principle

It seems that researchers have now been able to stop light. Here’s one of many articles about it:
http://www.nature.com/nsu/010125/010125-3.html

Now, since the momentum of the photons is very precisely known (it’s zero), doesn’t that mean that the position is then extremely unknown? Shouldn’t these photons be smeared across the entire universe?

Photons do have momentum.

momentum = p = h/wavelength

To expand:

p = mv in Newtonian physics
So in Relativity, p approx = m[sub]0[/sub]v for v << c

For any v < c, p = v * relativistic mass.
relativistic mass = m[sub]0[/sub]/sqtr(1 - v[sup]2[/sup]/c[sup]2[/sup])

p = m[sub]0[/sub]v is false for particles with zero rest mass like photons where v = c.

So, the stopped photons still have momentum? How can they have a wavelength if they aren’t moving?

Sorry, I read your post too quickly. I was talking about photons in a vacuum. My WAG here is that the velocity is approx zero which would allow some knowledge of the position. I don’t know about the wavelength of slowed (stopped) light.

Sorry.