/sci/ - Science & Math

I could be wrong, but I think the observation of the experiment does not affect the outcome. It just demonstrates how particles can behave as waves, regardless of whether or not they're being observed.

No, the observation does effect it.

An unobserved experiment will create a diffraction pattern behind the slits. An observed experiment produces two distinct lines behind the slits. Observation causes waveforms to collapse into particles

As for how, I truly wish I understood that too....

But, I took it to be that, since an observation must focus its attention on a single point, the irrelevant waveforms collapse in order to provide said data.

IE, you cannot observe a single photon refracting itself as a wave. But, you can observe a single photon going through one of two slits. Thus, when you choose to observe a photon going through one of two slits, that is exactly what you will see. But when you aren't looking, that photon exists as it truly is, an unobservable wave function that refracts itself as it passes through both slits simultaneously.

in relation to op's question
when people say that if you observe a particle spinning one way makes the particle it entangled with spin the other way, what exactly is happening, what kind of particles are they talking about and why can't 2 entangled particles spin the same way? also how does a particle become entangled to another particle?
i understand the experiment just not the basic phenomena upon which they are derived from.

>>5629658

this is what I just can't understand. I've spent several sleepless nights pondering this very thing.

>>5630145
>this is what I just can't understand. I've spent several sleepless nights pondering this very thing.

He's explained it very badly. It's a super oversimplification.

Yes 'observing' does break the diffraction pattern, and you could say the wavefunction was collapsing.

It's simpler than that though. When the electron goes through the slit, it's position is narrowed down to somewhere within the slit, we know where it is. Our information about it's position has increased (we know it's in the slit somewhere), so we need to lose some precision in the momentum by Heisenberg's uncertainty principle. The momentum gets a random kick in the direction it's been confined to. (Eg if it's a horizontal slit, the momentum will be kicked vertically because we've narrowed down the vertical position to somewhere within that slit). Making the slit smaller makes the diffraction pattern wider for the same reason.

Now. What if we make a measurement of which slit the electron went through? Observe it? To do that, we need to make a measurement of the electron coming out of a slit. We do that by shining a light on it. When we see it we're hitting it with a photon which is then bouncing back to our detector. In the process of hitting it the photon deflects the electron. We're ruining our nice diffraction pattern by trying to determine which slit it went through.

This is only one of many ways of looking at it. You could also use the wavefunction explanation or other path of least action arguments etc.

>>5630160
excellent. this seems to be a very sound explanation.

>>5630176
Another way of explaining it involves looking at the wavefunctions of the electron and how they interfere. When the electron passes through the pair of slits, we know it goes into a state like (ignoring constants) |left>+|right>. And we know that this state, when propagated to the screen, makes a particular interference pattern. The |left> and |right> states interfere with each other. But if you bounce a photon off the electron, you've changed the system, even if you haven't observed the photon yet. The state of the system is now something like |left, flash left> + |right, flash right>. These states won't interfere, because although the electron part will interfere alone, the photon part of the wavefunction will not interfere properly, so you see a different pattern (basically, a "classical" pattern).

This explains why you get collapse-like phenomena even when no photon bounces off. For example, if you shine a light on the right slit only, then half the time you won't see a flash, but the interference pattern is still totally destroyed. This is because the state |left, no flash>+|right, flash> can't interfere--you can't interfere flash and no flash (without a lot of effort and a totally different experiment). This problem comes up when trying to interfere large, hot objects like molecules since they can spontaneously emit thermal photons. Even if you never detect them, the interference pattern is destroyed because a state that had a "left photon emission" can't interfere with one that had a "right photon emission."

Why do we still think of particles, if everything is actually waves?

>>5632639
because they're also particles.

"observing" doesn't mean that a human or conscious being has to observe and understand it. Whether or not someone looks at it, putting anything inside the experiment that changes the way interference between waves occurs will change the outcome. The curious part is that "individual" wavicles can interfere with themselves.

>>5632695
>conscious

Here we go again.

>>5632639
Good base question, I watch people trip flat on this in what seems like about 40% of posts.

A wave, is a wave of particles.
Water waves are waves, ok as an example of a wave and they consist of particles of water. When there are more particles in aggregate the wave is at a high excursion and when there are relatively less particles the wave is at a low, considered together making a wave form.

Radio waves, photon waves and so on fit part of the basic concept of waves of water excepting a number of things but a wave is still a matter of our considering groups of particles.
Considering one is something else and it does not mean that each water molecule is shaped like a little ~ tilda.

If we can't figure out light propagating through a pair of slots in a piece of cardboard at the scale we can see and handle then we have exposed the truth of the shortfall of our understanding and theories in general.

>>5632738
>A wave, is a wave of particles.

What particles is the wave function of an electron made of?

>>5632745
If your 'the wave function of an electron' means a pulse of electricity in a wire at 600herz then I dare to answer you directly, that the highs of the pulses at 600hz are more electrons and the lows are short moments of fewer electrons.

If your 'wave function of an electron' is some feature interior to a single electron then ya got me you dirty rat and I am well unqualified to give a real answer. Particle physicists keep exploring at a lower scale and I am sure I think there is some resonance going on just inside an individual atom, and we may have people plumbing some resonance within just one electron I do not know! but I will not believe any present electron-microscope photograph of a wave within an electron though.

>>5632775
That's not what he meant. He was politely pointing out the fact that you do not understand quantum mechanics, and that your story only holds at the classical level. At the quantum level, where one has wave-particle duality, electrons can have properties of particles as well as those of waves. The double slit experiment demonstrates this. This is why it's revolutionary.

>>5632971
A reply, well I am a dissident versus a lot of our concept that we know what we are doing down there below atomic scale. It is okay to ponder wave-particle duality but we have not finished considering sense-nonsense duality either and one major nemesis is that we cannot see what we are doing down at that scale.

I know the field publishes new facts frequently but having it in print might not turn out to make the world flat after full consideration.

"Ya got me you dirty rat" is a quote from Humphrey Bogart depicting that he had been shot, it does not mean or convey that the person I was replying to is in fact an actual rat nor that they are certainly dirty.

>>5633021
On the other hand it does not either exclude the possibility of the other person being in actual fact a rat that is dirty. Or not dirty and a rat. And so on.

Assuming equal probabilities there's no more than 1/4 chance of subject being neither dirty nor a rat.

>>5632738
>A wave, is a wave of particles.
... but that's wrong. That would suggest that these particles, too, are made of waves, which are made of particles, and all of a sudden we've got an infinite hierarchy. Things don't work like that in real life.

Wave-particle duality states that any particle can also act like a wave, and vice-versa.

>>5632705
He said:
>"Observing" doesn't mean that a human or conscious being has to observe and understand it.
He was saying that consciousness, whether or not consciousness exists, doesn't matter.
>Here we go again.

>>5634688
Lets just assume all 'observers' are at a human level

Now, this being the case, could we not say that the particle, photon, is only acting that because of it's nature of being only 'information'? And that the receiver's only retrieving that closed loop only do to, again, the nature of the photon to maintain its property, otherwise it might as well be another, relatively, unacknowledged radio wave

>>5634739
"observing" has nothing to do with it. It's really bad wording when people describe it as such. To observe which slit the photon goes through, you have to change the experiment. By constraining the photon to a specific path, with polarizers, detectors, etc., you change the wave function and you change the outcome you see on the screen. Looking or not looking has absolutely nothing to do with it. "Looking" at photons requires that you change the outcome. There's no way to tell which slit the photon went through without perturbing it on its way through. It's an example of the heisenberg principle, if anything.

>>5629603
Short version : Bullshift

>>5634760

How does it mean should?

>>5634765
That...was not a sentence.

>>5634766

I might be somewhere.

>>5634768
You might be high.

>>5634754
Well I was saying it in relation to an electrons transformation, and how the particle would have to anticipate the interaction of what would subside for an observer (physical altering, detections) to operate the way it does, and that being the case then... well then we could rule out mass for being a universal information holder, still... its likeness and means of existence are oh so near to the transistor, I mean they might as well be the same thing in term of their placement, that being said I'm probably giving the transistor a little to much credit for what I consider legitimate properties lol

A cup of 0.0..01 anybody?

>>5634776
> infantile cartoons

>>5629603
The double slit experiment essentially verified that light can behave like a wave. After sending the light through two slits, they noticed areas that more light had hit compared to other areas. Some areas had no light where there was destructive interference. It is usually covered in a physics II course with optics.

>>5634777
>were not an infantile race

check your privilege

>>5629603
shhoop da whoop, ty for the excellent responses you garnesht OP