Comment on Observer
Kaput@lemmy.world 1 year ago
I have been tryin to find an actual demostration of this experiement and it seem impossible to find. can someone sow me this experiment done on a single setup. where you have a light source, two slits a screen and an ‘‘observer’’. That swithes from interference pattern to two lines, by switching the observer on and off. I am convinced that the science is solid, in its theoric and applied aspect. but that this interpretation of it is complete bullcrap. And i am annoyed by the '‘believe this cheap explanation’'that is repeated and nauseam. What is the actual equipment required, wave lenghts, slit sizes. I know This is science meme sub, where is the sub where i can find an actual two slit operator?
You can put together a version good enough for high schoolers with a laser pointer and some pencils.
To conceptualize thought, it might be better to set up some sort of wave table - some sort of tub of water you set up the slits in, then observe the patterns of constructive and destructive interference. (That’s why I did with students.)
Yes, thats a very easy demonstation of the wave nature of light, what bugs me is the demonstration that it’s also a particle that I feel is misleading. Maybe particle is not the right word to describe it’s nature.
You see it behave as a particle when you cover a slide and it simply passes through the single slit.
“Particle” is the right word to describe the nature of a photon, and so is “wave.” When you collapse a wave function by “observing it” - basically the wave/particle interacting with something - you find it as a particle somewhere.
Eg, imagine an atom surrounded by electrons. Until the electrons are “observed” - interact with something - they exist in a probabilistic “electron cloud.” Depending on energy level and sub shell (ie, the “quantum numbers” you might have encountered in chemistry - remember 1s^2 2s^2 2p^6?) there are places that the electron is more likely to be. An electron in 1s is likely to be closer to the atoms nucleus when observed. But it could also be on the opposite side of the universe - small chance, but possible. It exists as a probabilistic wave though until that wavefunction is “collapsed.”
This is why the photons going through the a single slit will behave like particles, and those through the double slit will behave like waves. They aren’t “collapsed” at the double slit. The single slit will only allow them to pass through as a particle.
But the vocab is unambiguous and correct - they are both “particles” and “waves.”
What are you trying to see exactly? There’s this video done with polarizers: youtu.be/unCXuRXpEhs Of course, it’s not an instant on/off but having an instant on/off doesn’t really change anything.
Thank you. Yes something like that. with lab grade equipment would be nice. I agree instant on/off is not required for my understanding.
en.m.wikipedia.org/wiki/Double-slit_experiment
Now rephrase the experiment s.t. you have to beams serviced from a singular beam. interfere the two beams with each other. If you measure on one beam path (e.g. Pol filter) you destroy the interference pattern.
You don’t really need an on/off switch.
By default you are not observing what slit it goes trough so you should always see the wave pattern.
starman2112@sh.itjust.works 1 year ago
I feel like calling it an “observer” is the worst thing since Ben Franklin decided to name positive and negative electrical charges. “Observer” implies that it’s someone watching the thing, when really it’s just the light interacting with something.
Kaput@lemmy.world 1 year ago
Yes, that’s what bothers me about the whole thing. All those ‘‘popular science’’ exposé telling us that if you just look at it, it will know and change from wave to particle. They put this big eye icon next to the slit and imply you are stupid if you dont just believe it as told. the experiment with polarized filter someone else showed me was interesting, but that’s not merely observing.