4 ms·

Doesn’t that imply that the incoming photons are spread out over the entire mirror, several meters?

Sharlin 5y ago
Hm? Yes, that’s how telescopes (and camera lenses) work!
NavinF 5y ago
Yeah I was also surprised to find that photons can be really big: https://youtu.be/SDtAh9IwG-I https://youtu.be/SDtAh9IwG-I Before I saw the experiments in that video, I assumed photons were about as wide as their wavelength.
- BobbyJo 5y ago
  Woah. Thank you. This is nuts.
- nazgulnarsil 5y ago
  amazing video. thanks.
- Maursault 5y ago
  That guy is hilarious.[1][2][3] I'd like to know what would happen if the split beam was sent through fibre optics to Pluto and back, if the interference pattern would persist instantly. [1] "It's a golden oldie..." [2] "... just to give the setup a nice high tech look and feel." [3] "The physics behind this is pretty hefty, and not, like, youtube video material."
- baq 5y ago
  From what little I know about quantum mechanics, the statement about changing the light source and expecting to not see an interference pattern is very surprising. I’d expect to see one.
  - superjan 5y ago
    Yes, pity that is not in the video.
  - jlokier 5y ago
    Different light sources emit with different "Coherence length". A continuous-wave laser has high coherence length, and a light source that isn't a laser at all has low coherence length even if it's monochromatic, for example a sodium lamp. The laser used by the presenter has a coherence length longer than (or in the same ballpark as) the difference in optical paths in their experiement, so they get a clear interference pattern. The Wikipedia article may explain. https://en.wikipedia.org/wiki/Coherence_length https://en.wikipedia.org/wiki/Coherence_length Since you can measure coherence length (and higher-order temporal and spatial coherence statistics), it is part of the information carried by light from a luminous object that is available for imaging by a suitably designed camera.

Hm? Yes, that’s how telescopes (and camera lenses) work!

Yeah I was also surprised to find that photons can be really big: https://youtu.be/SDtAh9IwG-I https://youtu.be/SDtAh9IwG-I Before I saw the experiments in that video, I assumed photons were about as wide as their wavelength.

BobbyJo 5y ago
Woah. Thank you. This is nuts.
nazgulnarsil 5y ago
amazing video. thanks.
Maursault 5y ago
That guy is hilarious.[1][2][3] I'd like to know what would happen if the split beam was sent through fibre optics to Pluto and back, if the interference pattern would persist instantly. [1] "It's a golden oldie..." [2] "... just to give the setup a nice high tech look and feel." [3] "The physics behind this is pretty hefty, and not, like, youtube video material."
baq 5y ago
From what little I know about quantum mechanics, the statement about changing the light source and expecting to not see an interference pattern is very surprising. I’d expect to see one.
- superjan 5y ago
  Yes, pity that is not in the video.
- jlokier 5y ago
  Different light sources emit with different "Coherence length". A continuous-wave laser has high coherence length, and a light source that isn't a laser at all has low coherence length even if it's monochromatic, for example a sodium lamp. The laser used by the presenter has a coherence length longer than (or in the same ballpark as) the difference in optical paths in their experiement, so they get a clear interference pattern. The Wikipedia article may explain. https://en.wikipedia.org/wiki/Coherence_length https://en.wikipedia.org/wiki/Coherence_length Since you can measure coherence length (and higher-order temporal and spatial coherence statistics), it is part of the information carried by light from a luminous object that is available for imaging by a suitably designed camera.