Can I ask a question here rather than main, I end up here anyway.

Can somebody explain to me the dual slit experiment in some detail. I understand the process and what the effect is , but I am struggling with the quantum weirdness, and have several questions.

If I emitted light through the two splits it will basically project stripes onto the adjacent surface to the slits, is that correct so far in basic form?


But if we try to observe this it knows we are observing it so changes itself into a particle and becomes just two lines on the adjacent surface , is that correct?

If my information is accurate and the answers to the above are yes , can you answer what device , devices are you are trying to observe the effect with?

Are these energy devices that emit EM radiation?

If you observe the effect by eye and have one of these devices hidden in a box, and quickly pull it out to try and catch it out, does that work?

 

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The question could be posted in Physics & Math, but seems to me a little confused. I used strike out to show which parts are not clearly related to the clasic double slit experiement.

The basic double slit experiment demonstrates the wave nature of light, in that a beam of light that passes through two closely situated slits will interfere with itself on the other side and result in light and dark bars on a screen. It will be there whether you are looking or not.

Interference patterns have been known for a very long time. They played a key role in how the Michaelson & Morley experiment worked.

Really as long as you stick to the question above, it should be OK in Physics &Math and you could get far better explanations there. Just be willing to listen...

 

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My understanding is that we can't measure it without affecting it. IOW - to determine which slit the particle passes through, we have to mess with it.

 

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Thank you for your reply , I asked about this because I watched a documentary earlier and it claimed that the double slit experiment was a part of quantum weirdness, claiming that the experiment that was to be observed by device would change it action of interference as if it knew you were trying to observe it, is this claim not true?

 

This the video I watched and the part I refer to is 22.48 minutes onwards for a few minutes long.

 

If you watch crank videos you get crank claims.

 

I know it is a crank video, I do not believe in a holographic Universe, but some of these videos have contents in them worth viewing, I think in the video they were referring to this -

''My understanding is that we can't measure it without affecting it. IOW - to determine which slit the particle passes through, we have to mess with it.''

What does this mean? does your measuring equipment some how have effect on the interference?

 

At the level of quantum mechanics, you often cannot measure something to a given level of precision without affecting it. (Not because the equipment isn't good enough - because it's not possible.) Refer to Heisenberg's Uncertainty Principle for a good explanation of this.

 

No.
They don't.
Avoid crank videos - they'll only confuse you further (which, in your case, is a very bad thing).

The guy's understanding is somewhat flawed.

Uh, if you set up an experiment to take a measurement then that experiment defines what you can measure.
E.g. if you have a cow that you want to know the height of then you use a tape measure: that means you don't measure the colour...

 

Thank you for the reference, I have read this before but did not entirely understand it , I have it added to my bookmarks and will review it with a fresh head tomorrow and may have some questions to help my understanding of it.
It did lead me to observer effect , which I understood instantly and will be applying that to another thread thanks.

 

Thank you for your reply , I will continue learning this tomorrow now .

 

Then make sure you apply it correctly (i.e. NOT the way you just did in your claim about white light/ mixture).
Because Billvon wasn't referring to the observer effect but rather the HUP.
They're two SEPARATE phenomena.

 

I referred to the double slit with light because it is a little more straight forward than when electrons are used or a beam of light is split and brought back together.

 

I would like today to firstly ask about the observation of the background screen that the stripes are on, I observe light stripes and dark stripes,

are the dark stripes the absence of light?

 

Christ!

 

That does not answer it, are the dark stripes the absence of light?

 

If you have to ask that, then your chances of understanding the double slit experiment or the uncertainty principle are nil. You are trying to run before you can walk. But yes, "dark" indicates the areas where less light falls and "bright" the areas where more light falls.

You can try looking up "interference fringes", if you want to understand how these arise. Google will direct you to several articles and there are also some helpful images. It is to do with a well-known wave phenomenon - constructive and destructive interference. But honestly, since I very much doubt that you yet understand waves, you are likely to find these articles too difficult.

 

Thank you for your answer, I already admit I have problems understanding this, I do not see how a wave function can give dark and light , dark and light in the experiment shown to co exist, I also do not see why it would be a vertical split, what causes the shadow of the dark areas, the slits inner sides?

 

Not wave function, just waves. This is not QM. It is straight forward wave behaviour, i.e it is an effect you can see with water waves etc as well.

This is basic school level physics, available in numerous books and on the web. (I remember observing interference fringes of light myself at school, using a glass plate and a lens.) So I am not going to lead you through it all. Just read about waves and interference and maybe the light will dawn. (As it were.)

 

You can see light and dark stripes with a water wave?

I am sorry this whole topic is making absolutely no sense to me, science says dark is the absence of light, in the experiment we see dark stripes, the absence of light, I observe a fanning out of the light that leaves the slits, and darkness stripes separating the light, I do not observe a wave, a wave crashes the sea shore in an equal line.

I will read up more on this, it is just the explanation of present seems a bit weird to the observational facts, I do admit it probably is my lack of understanding on this one.