Double Slit Experiment

How does science work? And what's all this about quantum mechanics?

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philosopher
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Re: Double Slit Experiment

Post by philosopher » Mon Dec 03, 2018 7:44 pm

A_Seagull wrote:
Mon Dec 03, 2018 1:47 am
philosopher wrote:
Sun Dec 02, 2018 7:36 pm
A_Seagull wrote:
Sun Dec 02, 2018 11:37 am


Yes you have a slight misunderstanding regarding the experiment. The particles do not interfere nor interact with previous or succeeding particles.

The particles interfere with themselves. They are best modelled as a wave which goes through both slits. Each slit then acts as a wave source. The waves emanating from each slit then interfere with each other. This results in a sequence of highs and lows at the detecting screen. These highs and lows, can be considered to represent the probability that the detector will detect a particle at that particular point. It requires a whole lot of particles to build up the pattern so that it can be seen. Each particle is entirely independent of every other.

Hope this helps.
What you say, contradicts what PBS Space Time says in this video:
https://www.youtube.com/watch?v=p-MNSLsjjdo
Why should I care? I generally don't follow links, and certainly not to videos,

If what I posted doesn't aid your understanding, well that is absolutely fine with me.

If you want to learn about the 2 slit experiment then wikipedia would be a better source of information than youtube. Or even better.. read a book. Or better still do your experimentation.. its not hard to see the diffraction pattern using light.
Youtube is always safe from malware. I understand if you never follow links to videos from non-youtube or non-vimeo sources, but you can always hover your mouse over the link before you click on it, and see at the bottom of your browser where it leads to. This link does indeed link to youtube.

- or - you could simply copy/paste the link into your browser, or at the very least go to youtube and search:

"The Quantum Experiment that Broke Reality".

And you can always trust PBS Space Time, because PBS Space Time is, although slightly popular science, in the more serious business of popular science.

It explains what actually happens, it is non-fiction, serious and trustworthy.

You can't do the double slit experiment properly using your own light. First of all, you need a laser - not hard to get though.
But you cannot fire single particles (photons/electrons) using home made equipment.

If you fire a single electron, one at a time at the 2 slits, you still get the interference pattern after firing many of those single particles, one at a time.

This is why I am talking about the thing that the first particle "tells" the second particle where to land on the screen, to create the overall picture of an interference pattern.

This is also described in the video, as well as Wikipedia, as well as in science books.

Atla
Posts: 2802
Joined: Fri Dec 15, 2017 8:27 am

Re: Double Slit Experiment

Post by Atla » Mon Dec 03, 2018 7:59 pm

philosopher wrote:
Mon Dec 03, 2018 7:44 pm
Youtube is always safe from malware. I understand if you never follow links to videos from non-youtube or non-vimeo sources, but you can always hover your mouse over the link before you click on it, and see at the bottom of your browser where it leads to. This link does indeed link to youtube.

- or - you could simply copy/paste the link into your browser, or at the very least go to youtube and search:

"The Quantum Experiment that Broke Reality".

And you can always trust PBS Space Time, because PBS Space Time is, although slightly popular science, in the more serious business of popular science.

It explains what actually happens, it is non-fiction, serious and trustworthy.

You can't do the double slit experiment properly using your own light. First of all, you need a laser - not hard to get though.
But you cannot fire single particles (photons/electrons) using home made equipment.

If you fire a single electron, one at a time at the 2 slits, you still get the interference pattern after firing many of those single particles, one at a time.

This is why I am talking about the thing that the first particle "tells" the second particle where to land on the screen, to create the overall picture of an interference pattern.

This is also described in the video, as well as Wikipedia, as well as in science books.
Umm no, watch those videos again, the particles fired don't interact with the prior or next particle, they interact with themselves.

It's something like: they get spread out all over the place (all over the universe), and take every possible path at the same time, interfering with themselves. Most of this cancels out and we get a wavelike distribution of possible paths. And then the particle coalesces into a single point again at the screen.

philosopher
Posts: 395
Joined: Fri Jun 08, 2018 3:37 pm

Re: Double Slit Experiment

Post by philosopher » Mon Dec 03, 2018 8:21 pm

Atla wrote:
Mon Dec 03, 2018 7:59 pm
philosopher wrote:
Mon Dec 03, 2018 7:44 pm
Youtube is always safe from malware. I understand if you never follow links to videos from non-youtube or non-vimeo sources, but you can always hover your mouse over the link before you click on it, and see at the bottom of your browser where it leads to. This link does indeed link to youtube.

- or - you could simply copy/paste the link into your browser, or at the very least go to youtube and search:

"The Quantum Experiment that Broke Reality".

And you can always trust PBS Space Time, because PBS Space Time is, although slightly popular science, in the more serious business of popular science.

It explains what actually happens, it is non-fiction, serious and trustworthy.

You can't do the double slit experiment properly using your own light. First of all, you need a laser - not hard to get though.
But you cannot fire single particles (photons/electrons) using home made equipment.

If you fire a single electron, one at a time at the 2 slits, you still get the interference pattern after firing many of those single particles, one at a time.

This is why I am talking about the thing that the first particle "tells" the second particle where to land on the screen, to create the overall picture of an interference pattern.

This is also described in the video, as well as Wikipedia, as well as in science books.
Umm no, watch those videos again, the particles fired don't interact with the prior or next particle, they interact with themselves.

It's something like: they get spread out all over the place (all over the universe), and take every possible path at the same time, interfering with themselves. Most of this cancels out and we get a wavelike distribution of possible paths. And then the particle coalesces into a single point again at the screen.
You don't understand the experiment!

Here's a wiki for you:

https://en.wikipedia.org/wiki/Double-slit_experiment
An important version of this experiment involves single particles (or waves—for consistency, they are called particles here). Sending particles through a double-slit apparatus one at a time results in single particles appearing on the screen, as expected. Remarkably, however, an interference pattern emerges when these particles are allowed to build up one by one (see the adjacent image).

Atla
Posts: 2802
Joined: Fri Dec 15, 2017 8:27 am

Re: Double Slit Experiment

Post by Atla » Mon Dec 03, 2018 8:24 pm

philosopher wrote:
Mon Dec 03, 2018 8:21 pm
You don't understand the experiment!

Here's a wiki for you:

https://en.wikipedia.org/wiki/Double-slit_experiment
An important version of this experiment involves single particles (or waves—for consistency, they are called particles here). Sending particles through a double-slit apparatus one at a time results in single particles appearing on the screen, as expected. Remarkably, however, an interference pattern emerges when these particles are allowed to build up one by one (see the adjacent image).
Nope, you don't understand the experiment. We send the particles one by one, and they land on the screen one by one, consistent with an interference pattern. But they don't interfere with each other.

philosopher
Posts: 395
Joined: Fri Jun 08, 2018 3:37 pm

Re: Double Slit Experiment

Post by philosopher » Mon Dec 03, 2018 8:30 pm

Atla wrote:
Mon Dec 03, 2018 8:24 pm
philosopher wrote:
Mon Dec 03, 2018 8:21 pm
You don't understand the experiment!

Here's a wiki for you:

https://en.wikipedia.org/wiki/Double-slit_experiment
An important version of this experiment involves single particles (or waves—for consistency, they are called particles here). Sending particles through a double-slit apparatus one at a time results in single particles appearing on the screen, as expected. Remarkably, however, an interference pattern emerges when these particles are allowed to build up one by one (see the adjacent image).
Nope, you don't understand the experiment. We send the particles one by one, and they land on the screen one by one, consistent with an interference pattern. But they don't interfere with each other.
But wait a second - if you fire particles one at a time, this implies that you fire those particles with some time in-between (fire, wait a second (not fire), fire a new particle, wait a second or two where you don't fire. Fire again etc. etc.) and so forth.

What you see is an interference pattern. You shouldn't. You should instead see a chaotic, random non-pattern.
But fire billions of them this way, and you see an interference pattern.

This means that those particles have been able to "communicate" across time and space telling the next particle where it should "prefer" to land.

"So, I landed here. Now, you, yes you next guy, you should have a higher likelyhood of landing over there instead. And you the third guy, you should probably land over there." This seems chaotic at first, but with many of those chaotically randomly chosed landings, they make up a pattern - an interference pattern.

As if the entire bunch of all the electrons - or even buckyballs - taken together make up a single wave that spans across space and time.

Atla
Posts: 2802
Joined: Fri Dec 15, 2017 8:27 am

Re: Double Slit Experiment

Post by Atla » Mon Dec 03, 2018 8:37 pm

philosopher wrote:
Mon Dec 03, 2018 8:30 pm
But wait a second - if you fire particles one at a time, this implies that you fire those particles with some time in-between (fire, wait a second (not fire), fire a new particle, wait a second or two where you don't fire. Fire again etc. etc.) and so forth.

What you see is an interference pattern. You shouldn't. You should instead see a chaotic, random non-pattern.
But fire billions of them this way, and you see an interference pattern.

This means that those particles have been able to "communicate" across time and space telling the next particle where it should "prefer" to land.

"So, I landed here. Now, you, yes you next guy, you should have a higher likelyhood of landing over there instead. And you the third guy, you should probably land over there." This seems chaotic at first, but with many of those chaotically randomly chosed landings, they make up a pattern - an interference pattern.

As if the entire bunch of all the electrons - or even buckyballs - taken together make up a single wave that spans across space and time.
No, they build up an interference pattern because each particle interferes with itself, and thus has a wave-like behaviour individually. It's even weirder than you thought.

philosopher
Posts: 395
Joined: Fri Jun 08, 2018 3:37 pm

Re: Double Slit Experiment

Post by philosopher » Mon Dec 03, 2018 8:43 pm

Atla wrote:
Mon Dec 03, 2018 8:37 pm
philosopher wrote:
Mon Dec 03, 2018 8:30 pm
But wait a second - if you fire particles one at a time, this implies that you fire those particles with some time in-between (fire, wait a second (not fire), fire a new particle, wait a second or two where you don't fire. Fire again etc. etc.) and so forth.

What you see is an interference pattern. You shouldn't. You should instead see a chaotic, random non-pattern.
But fire billions of them this way, and you see an interference pattern.

This means that those particles have been able to "communicate" across time and space telling the next particle where it should "prefer" to land.

"So, I landed here. Now, you, yes you next guy, you should have a higher likelyhood of landing over there instead. And you the third guy, you should probably land over there." This seems chaotic at first, but with many of those chaotically randomly chosed landings, they make up a pattern - an interference pattern.

As if the entire bunch of all the electrons - or even buckyballs - taken together make up a single wave that spans across space and time.
No, they build up an interference pattern because each particle interferes with itself, and thus has a wave-like behaviour individually. It's even weirder than you thought.
I'm aware it is wierder than I thought. I'm just trying to isolate the problems.

If you have a particle that is more like a wave (or only a wave), this wave travels through both slits, as a single particle spread out as a wave. Alright, got it.

Now, what you see on the back screen by this individual particle, is not an intereference pattern - yet - but a dot or line somewhere on the screen.

Then you wait 1 minute, before you press the fire-button.

You do the same thing, the same happens, nothing wierd there, yet.

But do this over and over again, with a minute in-between each shot, and you get the interference pattern.

How can an interference pattern emerge with more than a minute in-between each shot?

The past particles - waves if you like, did not only interfere with themselves. They interfered with the future particles as well, to create the intereference pattern.

And we haven't even got to the detector-problem yet...

Atla
Posts: 2802
Joined: Fri Dec 15, 2017 8:27 am

Re: Double Slit Experiment

Post by Atla » Mon Dec 03, 2018 8:50 pm

philosopher wrote:
Mon Dec 03, 2018 8:43 pm
I'm aware it is wierder than I thought. I'm just trying to isolate the problems.

If you have a particle that is more like a wave (or only a wave), this wave travels through both slits, as a single particle spread out as a wave. Alright, got it.

Now, what you see on the back screen by this individual particle, is not an intereference pattern - yet - but a dot or line somewhere on the screen.

Then you wait 1 minute, before you press the fire-button.

You do the same thing, the same happens, nothing wierd there, yet.

But do this over and over again, with a minute in-between each shot, and you get the interference pattern.

How can an interference pattern emerge with more than a minute in-between each shot?

The past particles - waves if you like, did not only interfere with themselves. They interfered with the future particles as well, to create the intereference pattern.

And we haven't even got to the detector-problem yet...
No, they only interfered with themselves, that's enough. I'd say technically that's not even a "classical" interference pattern on the screen, it's more like a path probability distribution that happens to look exactly like an interference pattern.

philosopher
Posts: 395
Joined: Fri Jun 08, 2018 3:37 pm

Re: Double Slit Experiment

Post by philosopher » Mon Dec 03, 2018 9:11 pm

Atla wrote:
Mon Dec 03, 2018 8:50 pm
philosopher wrote:
Mon Dec 03, 2018 8:43 pm
I'm aware it is wierder than I thought. I'm just trying to isolate the problems.

If you have a particle that is more like a wave (or only a wave), this wave travels through both slits, as a single particle spread out as a wave. Alright, got it.

Now, what you see on the back screen by this individual particle, is not an intereference pattern - yet - but a dot or line somewhere on the screen.

Then you wait 1 minute, before you press the fire-button.

You do the same thing, the same happens, nothing wierd there, yet.

But do this over and over again, with a minute in-between each shot, and you get the interference pattern.

How can an interference pattern emerge with more than a minute in-between each shot?

The past particles - waves if you like, did not only interfere with themselves. They interfered with the future particles as well, to create the intereference pattern.

And we haven't even got to the detector-problem yet...
No, they only interfered with themselves, that's enough. I'd say technically that's not even a "classical" interference pattern on the screen, it's more like a path probability distribution that happens to look exactly like an interference pattern.
Please explain "interfere with itself" in relation to creating an interference pattern for the coming future particles.

Here's my problem:

You fire one particle. It acts like a wave, as it spreads out like a wave, going through both slits. Got it.

Now, you still only fired ONE (1) UNO EIN particle, resulting in ONE (1) UNO EIN dot/line on the screen.
Not an inteference pattern.

The interference pattern only emerges later, when you fire the rest of the millions of particles.

Yes, I am aware it is not a classical interference pattern, but a random distribution of tiny dots on a screen, that looks like an interference pattern.

This, however, does change the fact that if it looks like an interference pattern, it is an interference pattern.

When you say a particle interferes with itself, you don't explain how this results in the future particles yet to be fired/shot at the screen, together make up the pattern. You have to make them interfere with each other, or it makes no sense.

seeds
Posts: 928
Joined: Tue Aug 02, 2016 9:31 pm

Re: Double Slit Experiment

Post by seeds » Tue Dec 04, 2018 12:07 am

philosopher wrote:
Mon Dec 03, 2018 9:11 pm
When you say a particle interferes with itself, you don't explain how this results in the future particles yet to be fired/shot at the screen, together make up the pattern. You have to make them interfere with each other, or it makes no sense.
I am speculating here, but I suggest that due to the fixed arrangement of the two slits in the wall, along with the fixed distance between the wall and that of the screen where the particles end up, it therefore means that when each individual particle passes through the slits,...

(allegedly as a wave that spreads-out and interferes with itself)

...the peaks and troughs of the waves travel along similar (fixed) pathways.

In turn, these similar pathways (trajectories) correspond with the landing positions of the particles on the screen – landing positions that eventually build up to reveal the specific (device-induced) shape of the interference phenomenon that is taking place in the space between the wall and the screen.

And lastly, the fact that the individual particles end up on different bands on the screen is either a purely random occurrence, or is based on something that we have no way of determining**.

**Perhaps there are infinitesimal variances in the way the emitting device fires the particles at the slits? Or perhaps there are some kind of cosmic whirls and eddies within the waves themselves that steer the particle onto the different (yet fixed) pathways, etc., etc.?

However, with that being said, I believe that your initial assertion about “entanglement” could also be correct.

For I agree that it is indeed possible that because of entanglement, each newly fired particle would instantly “know” (in a purely mechanistic way) the positions of their predecessors and thus take their own place on the screen in accordance with that “knowledge.”

In other words, because of entanglement, it is quite plausible that all particles within the universe have an “omniscient” (for lack of a better word) awareness of each other’s status - (again, in a purely mechanical fashion).
_______

Atla
Posts: 2802
Joined: Fri Dec 15, 2017 8:27 am

Re: Double Slit Experiment

Post by Atla » Tue Dec 04, 2018 7:58 am

philosopher wrote:
Mon Dec 03, 2018 9:11 pm
Please explain "interfere with itself" in relation to creating an interference pattern for the coming future particles.

Here's my problem:

You fire one particle. It acts like a wave, as it spreads out like a wave, going through both slits. Got it.

Now, you still only fired ONE (1) UNO EIN particle, resulting in ONE (1) UNO EIN dot/line on the screen.
Not an inteference pattern.

The interference pattern only emerges later, when you fire the rest of the millions of particles.

Yes, I am aware it is not a classical interference pattern, but a random distribution of tiny dots on a screen, that looks like an interference pattern.

This, however, does change the fact that if it looks like an interference pattern, it is an interference pattern.

When you say a particle interferes with itself, you don't explain how this results in the future particles yet to be fired/shot at the screen, together make up the pattern. You have to make them interfere with each other, or it makes no sense.
You know what, I said it 4 times, you disregarded it 4 times, if you don't believe it then watch the videos or read the books you mentioned.

Atla
Posts: 2802
Joined: Fri Dec 15, 2017 8:27 am

Re: Double Slit Experiment

Post by Atla » Tue Dec 04, 2018 8:13 am

seeds wrote:
Tue Dec 04, 2018 12:07 am
However, with that being said, I believe that your initial assertion about “entanglement” could also be correct.

For I agree that it is indeed possible that because of entanglement, each newly fired particle would instantly “know” (in a purely mechanistic way) the positions of their predecessors and thus take their own place on the screen in accordance with that “knowledge.”
No, this kind of entanglement can't happen here, and this kind of extra knowledge can't happen here either.
In other words, because of entanglement, it is quite plausible that all particles within the universe have an “omniscient” (for lack of a better word) awareness of each other’s status - (again, in a purely mechanical fashion).
_______
However, the universe could be fully entangled anyway.

philosopher
Posts: 395
Joined: Fri Jun 08, 2018 3:37 pm

Re: Double Slit Experiment

Post by philosopher » Tue Dec 04, 2018 10:17 am

Atla wrote:
Tue Dec 04, 2018 7:58 am
philosopher wrote:
Mon Dec 03, 2018 9:11 pm
Please explain "interfere with itself" in relation to creating an interference pattern for the coming future particles.

Here's my problem:

You fire one particle. It acts like a wave, as it spreads out like a wave, going through both slits. Got it.

Now, you still only fired ONE (1) UNO EIN particle, resulting in ONE (1) UNO EIN dot/line on the screen.
Not an inteference pattern.

The interference pattern only emerges later, when you fire the rest of the millions of particles.

Yes, I am aware it is not a classical interference pattern, but a random distribution of tiny dots on a screen, that looks like an interference pattern.

This, however, does change the fact that if it looks like an interference pattern, it is an interference pattern.

When you say a particle interferes with itself, you don't explain how this results in the future particles yet to be fired/shot at the screen, together make up the pattern. You have to make them interfere with each other, or it makes no sense.
You know what, I said it 4 times, you disregarded it 4 times, if you don't believe it then watch the videos or read the books you mentioned.
Saying something does not equal to explaining it.
You come up with a saying that the particle interferes with itself, not the other particles.

But you don't explain it.

I've watched the video several times. I still get the picture of a particle interfering with other particles.

Atla
Posts: 2802
Joined: Fri Dec 15, 2017 8:27 am

Re: Double Slit Experiment

Post by Atla » Tue Dec 04, 2018 10:43 am

philosopher wrote:
Tue Dec 04, 2018 10:17 am
Saying something does not equal to explaining it.
You come up with a saying that the particle interferes with itself, not the other particles.

But you don't explain it.

I've watched the video several times. I still get the picture of a particle interfering with other particles.
I wrote:

It's something like: they get spread out all over the place (all over the universe), and take every possible path at the same time, interfering with themselves. Most of this cancels out and we get a wavelike distribution of possible paths. And then the particle coalesces into a single point again at the screen.

Atla
Posts: 2802
Joined: Fri Dec 15, 2017 8:27 am

Re: Double Slit Experiment

Post by Atla » Tue Dec 04, 2018 10:53 am

philosopher wrote:
Tue Dec 04, 2018 10:17 am
I've watched the video several times. I still get the picture of a particle interfering with other particles.
I watched the video you mentioned https://www.youtube.com/watch?v=p-MNSLsjjdo

The guy says: "No, the pattern emerges in the distribution of final positions of many completely unrelated photons. How can that be? Each photon has no idea where previous photons landed or where future photons will land yet each photon reaches the screen knowing which regions are the most likely landing spots and which are the least likely. It knows the interference pattern of a pure wave that passed through both slits equally and it chooses its landing point based on that.
...
We have to conclude that each individual photon, electron, or buckyball travels through both slits as some sort of wave.
That wave then interacts with itself to produce an interference pattern, except that here, the peaks of that pattern are regions where there's more chance that the particle will find itself
."

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