Young's Double Slit Experiment

This shows Thomas Young's double slit experiment using a laser pen and a couple of pencil leads. When light shines through two slits between the leads, the two waves coming out interfere and the result is shown on the wall. Interference also occurs with one slit, because light wavelets from each side of the slit interfere with each other. The difference is that with two slits, there is an amplitude envolope not seen with a single slit. However, this is not seen in this video.

Category:

Science & Technology

Tags:

• light
• waves
• guthlaxton

[rmtglass1]

Great vid!

[flobber238]

@rmtglass1 Thank you!

[flobber238]

@Hannsfeld Hi, a measurement device isn't accurate. It's when the light interacts with the molecules on the wall. They act as a measurement device. Then the wave fn is collapsed.

[Hannsfeld]

Yeah, and you were looking right at it (even filmed it on video) and it didn't collapse the wave function. I have never seen an indication of what the "measurement device" is supposed to be, and am still skeptical that interaction from it is causing the collapse.

[singingcera]

Your skepticism is well placed. I think part of the deal is that you really can't quite tell which slit a photon is going through, but you can tell if you use an electron cannon instead, by bouncing a photon off the electron. However, the photon bumps the electron, and destroys the interference pattern. So we use a lower energy photon, that's "gentler," and that bumps the electron less, but we lose more certainty about the electron's path. Point is: observing *is* physical interaction.

[rmtglass1]

Check out rmtglass1 channel

[nuclearheadache]

@1simonmatthews I'm not sure what to think. There are certainly some troubling implications here. It DOES all seem to suggest that our awareness affects the outcome. However, I'd like think that's it more a matter of us just not completely understanding how things behave at such a small level, something we're missing, something that we're either physically altering without realizing it, or something that we're misunderstanding in our attempted measurement.

[1simonmatthews]

@nuclearheadache Do you think it could be our brains that are collapsing the wave, in the same way as our brain creates illusions? In this idea, the wave never really collapses at all, but only in our minds.

[nuclearheadache]

@1simonmatthews As to what kind of measuring device they use, I don't really know. I've wondered about that myself, though. Surely someone here must know. Anyone? Anyone?

[nuclearheadache]

@1simonmatthews Looking back at this old comment, I realize now that the phrase "they don't mean observation of any kind" does indeed sound like I'm saying "it has nothing to do with observation as we think of it." What I was trying to say what they didn't mean just any old kind of observation...you know, like walking into room and going, "Hey look! It's the Double Slit Experiment" ;D

Sorry if I confused you, or anyone else.

Continued ->

[chrishughes583]

meant to say "the term "measurement" is often misused" oops

[chrishughes583]

The often misused. The point is that when the wavefunction/particle interacts with another quantum object, the interference causes the wavefunction to collapse to a more definite position. It is impossible to measure without interaction, with light being the most common information carrying tool but light causes wavefunctions to collapse. The double slit experiment reveals more about how the particle travels. To know which slit it goes though would require closing them, forcing "measurement".