Thomas Young's Double Slit Experiment

Seeing light in a different way. Ever wonder what happens to light when it gets in its own way?

License: Creative Commons BY-NC-SA

[mothug]

Thank you for shedding light on this subject. It is articulate and well explained. 🙏🙏

[Khyatii_Verma]

i skipped a 1000 videos for this MIT explanation.
worth it

[MITKVideos]

For the best explanation I'd probably go to the Feynman videos, but the thrust
of the result is that photons are particles and can be observed as such. The
wavelength and wave properties all relate to the probability of finding any one
photon in some region, and the interference pattern we calculate classically
describes how we expect the photons to be distributed on the screen.

cont...

[MITKVideos]

The pinhole-pair itself is not covered, but it is really small in the center of
the disk. The tape (and tinfoil below it) is to keep stray light out of the
tube. To see the image you have to look through the tube, through the pinholes,
at a light source. My best results were from streetlights and stoplights at
night. To avoid damage to your eyes you do NOT want to use this type of system
to observe laser light or light from the sun.

[MITKVideos]

@NothingMatters1991: At the laser power levels used in the video there are a significant number of
photons traveling through the system at once and we can't distinguish by eye
the impact individual photons, and we're not observing if the photons passed
through one slit or the other.

cont...

[ArtisanTony]

Why did you not mention what happens when the photons are observed or not? Seems this is the heart of the experiment.

[MITKVideos]

It's pretty cool because in that video
you clearly see the impact of individual photons as discrete points, but the
resulting pattern is what you would expect from wave-like behavior.

[ashitasingh]

Have you used coherent light sources in this experiment? I am not able to understand why the intensities of the maxima keep decreasing... could someone please help!

[skepticalgenious]

I'm sad I didn't get to see a single photon emitter with results from it being observed vs not being observed. Thank you for the demonstration.

[schmetterling]

Linear superposition means that light never gets in its own way. The physical conditions for gamma-gamma scattering and vacuum polarization are nowhere near met for visible light at the kinds of intensities that we are talking about here.

[albertharvey]

I haven't seen yet if these double slit experiments are done in a total vaccumm or if the air moved rapidly during test Albert Harvey Rotary Engines

[picolodaemao]

What happens to the particles that hit the barrier? They whould be bouncing and making another patter somewere else. A patter that is not being observed. And if the pattern is not being observed, will it be afected when the experiment IS OBSERVED?

[MynameisS_A]

I love how the light pew-pews from a candle.

[MITKVideos]

It is possible to do the experiment with a small number of photons so that only
one photon at a time passes through the system, and with the right detector you
can observe the impact of individual photons on the screen. I think the
University of Leiden has YouTube video of the photon by photon buildup of an
interference pattern on a CCD camera.

cont...

[doddysk]

Great videos. Thanks. Theorist here trying to remind myself of what doing optics actually looks like.

[maged.william]

At 6:00 i thought you will say "Warning you might see a parallel world", still cool though

[Abhinandan]

Also, I performed double Lens experiment with Ample Sunlight and Two Lenses as apparatus to THRILL MY Friends in 1987 AD. Let me try recollecting what all did. It is fun to share. Also, it reminds that two experimenting humans can discover the same mystery of nature's phenomenon independently in two geographical location and at different timelines. It is all about who documented it first and made widely publicly available.

[vivekn.]

Thanks i needed this for my science fair project!!

[mayamoimayamoi]

nice job. I'm wondering if no one's tried to slow the thing being tested down. Perhaps making it pass through a medium or a very very cold vacuum?  Also, Sean Carroll speaks of everything being a field and I'm imagining a wave or disruption in a field. It's certainly an odd thing this dual nature of stuff. The peaks in the waves being seen as particles or probabilities for particles etc. Light passing through a vacuum without a medium to carry the wave is another strange one that brought us back to particles and corpuscles didn't it? I'm still not seeing how it can be both forms, it's especially strange when you're talking about one atom or photo at a time. I hope this is resolved in my lifetime. Excellent thought provoking video presentation.

[acuaman]

Please can someone explain, in simple terms, the reason why the wave is transformed in a solid particle when observed? Thanks for the answer.