Physical Science 7.3e - The Double Slit Experiment

[baconbag]

This is what they teach in 8th grade nowadays? I learned about the 9 planets when I was in 8th grade.

[MajorMcDoom]

The edges of shadows being fuzzy has nothing to do with the bending of light. It has to do with the fact that light sources in real life are never single points, but occupy some area. The totally dark area is the umbra, where none of the light reaches. The not-totally-dark area is the penumbra, where only some of the light reaches.

[MajorMcDoom]

@MajorMcDoom Of course, light bending still has a small effect on the edge of shadows, but it's so minute that it's insignificant compared to the aforementioned effect.

[MrPhysicsFan]

This might be the right place to ask. If electrons "theoretically" travel all over the universe to get through the slit, how do they do this without travelling faster than light? It might be a stupid question, I know!

[whisperinthe619]

@MrPhysicsFan see .... electrons travel with a speed less than in light only in their fixed orbits ...... as in atoms ..... but when they are free .... as in photoelectrons .... they behave as waves .... (I GUESS )

[jayejayeee]

some great inforamtion here thanks

[xTruncz]

Particles, such as Electorns, also have a wave-particle duality. Electrons can be shot through a slit using an electron beam onto a screen to show a line of electrons, as expected. However, sometimes, when electrons are shot towards a double slit, they can produce an interference pattern! My physiscs teacher told me this is called 'Electron Diffraction'. A way of showing electrons acting with a particle like behaviour is shooting them through a magnetic field, as they will be deflected.

[EternalDestiny95]

Question; does the colour used during the Young double slit experiment affects the distance or any other characteristics of the wave produced?

[derekowens]

@EternalDestiny95 Yes, a different color corresponds to a different frequency and wavelength, so the interference patter would be different. But there would still be an interference pattern, which is the main point.

[EternalDestiny95]

@derekowens could you do another video to explain that? and thank you by the way. :)

[teerna1]

Thanx a lot for this..

[lol9399]

great work..thank you ;)

[zerogee11]

what happens when the troughs of two waves intersect?

[nickharvey7]

Could Quantum Physics represent a process of continuous change that we see and feel as the flow of time itself?

The future is always uncertain!

This theory is based on two postulates

1. Is that the quantum wave particle function Ψ represents the forward passage of time ∆E ∆t ≥ h/2π itself

2. Is that Heisenberg’s Uncertainty Principle ∆×∆p×≥h/4π that is formed by the w- function is the same uncertainty we have with any future event

[97100suz]

this is amazing and so clear and well presented. thank you!

[Ilamarea]

How about dispersing the 'duality' thing and say that light is energy (Of which matter consists) that travels in a wave-like pattern, exactly like water?

W8...

The water is enviroment of wave which is energy.

The light is both it's enviroment and energy. Does that matter?

Have this experiments been tried in vaccum space?

If the results are the same then light is not m... My brain's starting to hurt and there is not enouugh space HERE YT!@!! ><

[MRKetter81]

@Ilamarea It's a wave

[kevinstuartfr0st]

young's double slit experiment like you've never seen before

watch?v=yNeHYhvQXic

[amynp2007]

8th grade where??

[derekowens]

@amynp2007 This course is something similar is often taught in grade 8 or grade 9 in schools in the USA.

[tsjoencinema]

It's a probability wave. Not just light acts this way. But all matter.

[derekowens]

@tsjoencinema Right on. We don't get into that at the 8th grade level, but yes that's correct, and it's fascinating stuff.

[tsjoencinema]

@derekowens It's mind blowing that experiments with single photons produced the same results.

[canirip2001]

@tsjoencinema yup electrons act as waves too but theyll when they are being observed..weird

[xanox02]

Make me think of string and M theory ...

[MsGenius000]

Can you do a series of videos about special relativity?

[derekowens]

@MsGenius000 I actually do have some plans for exactly that. Lots of other projects going on at the moment though...

[soulreaperichig0]

Great videos Keep going

[EllieGouldingFan]

Thank you!

[nirbija]

Well done video, derekowens. lol

[MopDMTBARTL]

It is either a wave or a particle depending on the frequency right? or the wave is made up of particles?

[MopDMTBARTL]

great videos by the way. thanks a lot!!!!

[derekowens]

@MopDMTBARTL A wave and a particle are two fundamentally different things. Light is mysterious in that it can be either. It doesn't depend on the frequency.  It really depends on the experiment. Some experiments demonstrate the wave nature of light and some experiments demonstrate the particle nature of light.

[MopDMTBARTL]

@derekowens - thx!

[smarthandsomeguy]

I think it's important to point out that the particle wave duality is true for objects with mass as well, ie. Electrons and even whole atoms and molecules. Which makes it even stranger.

[sullivanseven]

Your voice is so grounded

[zhangyuting72]

amazing video! i like your teaching style!

[kaisaraali]

Man great video. I would have spent another 3 hours reading book without understanding if I hadn't watched this video

[sprianka1]

What are the experiments which explain the particle nature of light? Or is it too complicated to explain over youtube?!

[utubepredator]

I see everywhere the double slit experiment is using elongated parallel openings in the first wall. What about a double-pinhole experiment? would a similar pattern appear? Or would it become a double-camera obscura?

[utubepredator]

Why only 2 people said light is a particle?  Well actually that's only one people. Einstein is a reincarnation of Newton.

But seriously, do you know of any experiments showing the light to be both particle and wave?

I also wonder if the entire matter (fields included) is not "just as dual" as light, only that it does not show this duality under any known conditions. Perhaps because only light has that special parameter or characteristic that makes it observable.

[utubepredator]

05:05 - 05:20 I really don't think light diffraction has anything to do with fuzzy shadow edges : in nature & in normal environment, there is NO single-point light source. Sun is not a single point, bulbs' filament is not a single point, etc etc.

On another note, diffraction should make it impossible to have camera obscura. So what is actually happening here?

[derekowens]

@utubepredator That's a good point. A lot of edge effects in shadows come from the light not being a point source, and the sun is certainly not a point source, even at 93,000,000 miles.

[NicholasLeeson]

Hi Derek, great video. I have subscribed. Can I ask what you are using to create your video with respect to the writing?

[xoloser3]

Holy cow.

[Marchiu5]

Men you are Brilliant! best explaining video on youtube. You made me subscriber

[joejacksonriley]

Derek, you should do more advanced physics too. Like AP Physics B or C.

[derekowens]

@joejacksonriley Thanks, and that's a good thought. I used to teach AP Physics C, several years ago. I would love to put some new physics lessons together again.  Maybe one day. Too many projects going at the moment, though. But one day...

[av733]

This would be better if there were some calculations on interference.

[porkypine1888]

Matter like bullets don't bend? Haven't you ever seen Wanted! On a serious note love your series, thanks so much!

[zackboomer]

khan academy

[NeerodhaCE]

If we consider a diagram of the intensity pattern of the light that reach the screen from the two slits, why is the intensity maximum at the middle(near y axis). I mean why is it maximum when there are other places that constructive interference occur?

[NicholasLeeson]

@NeerodhaCE

I believe it is because the wave reaches the center of the screen first, and thus the electrons in this particular area are more likely to absorb this energy before the electrons at farther locations.

[NeerodhaCE]

Can you please tell me what kind of pattern to expect on the screen if light contains particles?

[YouSpamTard]

It looks like one blue boobie and one yellow bubbie, it seems nobody has mention the obvious variable of ricashae

[UOTLTube]

today i learned about the History of light...

[joncl1]

you should've mentioned about the electron obsever double slit. I imagine this discovery is at least somewhere around the scientific caliber of the discoveries you covered.

[derekowens]

@joncl1 Yes, good point. The electron's behavior in the double slit is certainly significant. I take it that you are referring to the wave nature of matter and DeBroglie's ideas. Probably appropriate for a more advanced class, but yes, very significant.

[joncl1]

@derekowens indeed that's what I was referring to. In my speculation it adds a bit of validity to the "vibrational" theories such as string and M. And almost wholly supports the quantum theorems (laws in my opinion). I've read other scientists work in this field, and they have proposed profound new ideas of interconnectivity in all matter. And when you put the resultsof replication in Bose-Einstein Condensates with that, it all seems more plausible.

[Mrtassan]

Wavicle!!! =D

[jubair478]

@Mrtassan 

[HardstyleMatt]

Very nice video. I guess the next thing for physicists to find out is what causes photons to work differently as waves and particles. Like what kind of change makes them act differently.

[deductivist]

Not all scientists have accepted wave-particle duality. There is a large and growing movement in QM of researchers that accept the Many-worlds interpretation.

[Bedoljos]

wow man great explanation, my chemistry and physics teachers suck. thank you so much now it all makes sense.

[superfunny1972]

Ty man,Liked it...

[HIGHandFLYandRYE]

newton and einstein are trying to screw with us hahah.... also the colours you use in this are a good choice

[RandomCrazyApple]

Wow, this is really helpful :D

[kays1x]

what program do you use?

[kays1x]

i love this video. can i have some kind of contact with you? i am in a science research class and i think you can help me greatly. thanks<3

[kekothegeko]

THANK YOU A MILLION! My teacher's english is not the best and this made it very clear.

[linshenjie321]

light is an eletro-magnetic radiation

[mowemant]

very helpful man

[sweetnonni]

i love the video very much

[dninjal]

i like these videos very informative ^.^

[huppeldiehasie]

@goodagofilms

as derek said, nothing can travel faster than the speed of light in a vacuum (c). it's not possible.

but, if it was possible, then you have to look at it from this point of view: if you were to beam a message into space at 100 km/h, then got it returned at 200 km/h, would you be able to talk to yourself in the past?

[aarperry]

@huppeldiehasie wouldnt the message only be returned to you in half the time it took for it to be sent? for example i send the message which will take an hour to be recieved therefore i should expect a response in 1.5 hours of when i sent the message

[wacastervids]

how do you make these great videos?

[cipro426]

thanks

[gamesbok]

Huygen's Theory od Secondary Wavelets, and he was writing in 1660.

[derekowens]

I don't think that question can be answered (at least not by me!) because according our theories, the message could never travel at twice the speed of light. If the message is sent via a light wave, then it is traveling at the speed of light, which is a constant.

[goodbyelonglive44]

@derekowens isnt his partical duality already answeed through mathematical equations? I mean physicaly its impossible to believe, but the particles behave as a wave in a mathematics model, so its convincible thaT Such a thjing is possible because common sense are limited.

[goodagofilms]

If i beam a message into space at light speed, then got it returned at twice the speed of light would i be able to talk to myself in the past.

[BR177]

@goodagofilms not possible in this world