I briefly mentioned Femto-Photography as a promising new technology in the one of the American Revolution posts.
Here I want to illustrate something about it that raises a few questions for me regarding quantum physics and the present model of it.
Here's the Video:
At around 1:36 you'll see the packet of light he has filmed.
My questions revolve around the packet of light itself. Not the filming of it.
1) The light is shot from a laser pointer. Which makes it coherent.
2) Since the camera is at an angle to the light, why do we see the light at all if the photons are all going coherently in a straight line?
Well, the packet has a great many photons and some are being scattered by the molecules in the air and thus reflecting in the direction of the camera.
Plausible. But I'm willing to bet that even with a powerful laser far more intensely coherent shot through a vacuum, and sending a tiny number of photons at once that we would still see that packet of light even as the camera is oblique to it.
If that's true, I'm wondering if we have to rethink our whole notion of a photons as wave/particles. How do we see photons that aren't aimed at us? Our eyes or cameras? That's what I'm wondering.
Any ideas?
3 comments:
"Since the camera is at an angle to the light, why do we see the light at all if the photons are all going coherently in a straight line?"
Coherence is a function of phase, not of direction. Indeed, part of the description (not definition) of a photon is the NON-directionality of light.
The question you raise, "How do we see photons that aren't aimed at us?" is a-priori misinformed.
Photons are not aimed.
http://en.wikipedia.org/wiki/Introduction_to_quantum_mechanics
http://www.fnal.gov/pub/inquiring/questions/radiationdir.html
http://www.colorado.edu/physics/2000/lasers/lasers4.html
http://en.wikipedia.org/wiki/Photon_mapping
Radiation direction was the most relevant article, I think, but not quite right.
For example, if are perpendicular to a laser beam shot through very clear air, we can't see it. Only when it is scattered by mist or smoke do we see the beam; so there, light is directed, and since it's not directed at our eyes, we don't see it.
Thus, I don't think we can photograph "packets" of laser light obliquely through a clear vacuum. The photons have to be scattered to become random in direction.
Yep, I misinterpreted all 3 articles. (I'm not being facetious; I really did misread them.) I'd claim "non-sobriety" but that's no excuse.
I'm sorry, Mark.
Post a Comment