NationStates Jolt Archive

Those Goddamn slit experiments! I've been scratchin' my noggin' for the past three sleepless days, and I still can't figure it out. Maybe I'm going about it the wrong way...

Confused? I am, too! The slit experiments have been done since the 19th century using photon and electrons. It is a very well established fact that the outcome is indeed true, we just have no clue how the Hell it works.

The slit experiment works with having a slit in a wall, and then a wall behind that. They send a bunch of photons through, and you get exactly what you'd expect: a beam of light on the other side.

So what happens when you have two slits in the wall and you send a bunch of photons through? I'm guessing (unless you already know about the slit experiments) that you'd have two beams of light. No! Instead, you get an interference pattern.

In case you don't know, an interference pattern is what you get when you have a still pond and drop two pebbles side by side a small distance apart. The ripples and waves caused by pebbles disrupting the water mix and interfere with each other, creating a pattern called an interference pattern. This same effect is observed in the slit experiment where there are two slits.

This can be explained that light, and other energies, are although made up of individual parts (electrons, photons, atoms, etc,) have a wave-like manner.

Also, when they have around five or more slits in the experiment, there are beams of light, but every other beam of light is shown. So if there are five slits, there are two or three beams of light shown (I'm not sure if it was two or three, or if the experiment was done with six or more, so you can disregard this part if you want.)

But this is where things start to make no sense...

If you send a SINGLE photon through, you'd expect no interference pattern since there is nothing to interfere with it.

Wrong again!

They send in a single photon at a time, but an interference patter is still shown, EVEN THOUGH THERE IS NO OTHER PHOTONS (or electron, among other things that were not detected) THAT COULD INTERFERE WITH IT.

WTF??!!!

How can a photon be interfered by another photon that is not there?

But, I guess that's quantum mechanics for ya: it makes no Goddamn sense.

I need sleep.

Yes you do need some sleep.

And I hate Physics too, too much Math in it.

Those Goddamn slit experiments! I've been scratchin' my noggin' for the past three sleepless days, and I still can't figure it out. Maybe I'm going about it the wrong way...

Confused? I am, too! The slit experiments have been done since the 19th century using photon and electrons. It is a very well established fact that the outcome is indeed true, we just have no clue how the Hell it works.

The slit experiment works with having a slit in a wall, and then a wall behind that. They send a bunch of photons through, and you get exactly what you'd expect: a beam of light on the other side.

So what happens when you have two slits in the wall and you send a bunch of photons through? I'm guessing (unless you already know about the slit experiments) that you'd have two beams of light. No! Instead, you get an interference pattern.

In case you don't know, an interference pattern is what you get when you have a still pond and drop two pebbles side by side a small distance apart. The ripples and waves caused by pebbles disrupting the water mix and interfere with each other, creating a pattern called an interference pattern. This same effect is observed in the slit experiment where there are two slits.

This can be explained that light, and other energies, are although made up of individual parts (electrons, photons, atoms, etc,) have a wave-like manner.

Also, when they have around five or more slits in the experiment, there are beams of light, but every other beam of light is shown. So if there are five slits, there are two or three beams of light shown (I'm not sure if it was two or three, or if the experiment was done with six or more, so you can disregard this part if you want.)

But this is where things start to make no sense...

If you send a SINGLE photon through, you'd expect no interference pattern since there is nothing to interfere with it.

Wrong again!

They send in a single photon at a time, but an interference patter is still shown, EVEN THOUGH THERE IS NO OTHER PHOTONS (or electron, among other things that were not detected) THAT COULD INTERFERE WITH IT.

WTF??!!!

How can a photon be interfered by another photon that is not there?

But, I guess that's quantum mechanics for ya: it makes no Goddamn sense.

I need sleep.

Question - how "static" is the orbital pattern of an electron when it's not being bumped out of an energy level?

did you remember to carry the one?

maybe you should recalibrate the deflector dish :p

This is that post ---
































































...and this is my head.

This is that post ---
































































...and this is my head.

http://video.google.com/videoplay?docid=-7035079995166332549&q=Brain+on+drugs&total=894&start=0&num=10&so=0&type=search&plindex=0

http://video.google.com/videoplay?docid=-7035079995166332549&q=Brain+on+drugs&total=894&start=0&num=10&so=0&type=search&plindex=0

Drugs keep my brain from sticking to the pan?

It's simple. The photon (or electron) goes through both slits simultaneously, thus interfering with itself.

Quantum mechanics, like life, is weird.

In the quantum universe, it is possible for particles to flit in and out of existence. This experiment helped to prove that light is both a particle and a wave at the same time. It interferes with itself.

Quantum physics is not supposed to make sense in the real world. It doesn't apply in the real world, it applies to the world of the small. (Which is why its so goddamned hard to get Relativity and Quantum physics to work in the same unified theory, because they both apply and yet contradict each other.)

It's simple. The photon (or electron) goes through both slits simultaneously, thus interfering with itself.


Sounds a *lot* like my personality. :eek:

Drugs keep my brain from sticking to the pan?

More liquidy, i suspect.

Those Goddamn slit experiments! I've been scratchin' my noggin' for the past three sleepless days, and I still can't figure it out. Maybe I'm going about it the wrong way...


I need sleep.

If you don't understand it, God did it.







The actual answer, of course, is that 'a photon' is only a probability, not a lump of 'stuff'.

Those Goddamn slit experiments! I've been scratchin' my noggin' for the past three sleepless days, and I still can't figure it out. Maybe I'm going about it the wrong way...

Confused? I am, too! The slit experiments have been done since the 19th century using photon and electrons. It is a very well established fact that the outcome is indeed true, we just have no clue how the Hell it works.

The slit experiment works with having a slit in a wall, and then a wall behind that. They send a bunch of photons through, and you get exactly what you'd expect: a beam of light on the other side.

So what happens when you have two slits in the wall and you send a bunch of photons through? I'm guessing (unless you already know about the slit experiments) that you'd have two beams of light. No! Instead, you get an interference pattern.

In case you don't know, an interference pattern is what you get when you have a still pond and drop two pebbles side by side a small distance apart. The ripples and waves caused by pebbles disrupting the water mix and interfere with each other, creating a pattern called an interference pattern. This same effect is observed in the slit experiment where there are two slits.

This can be explained that light, and other energies, are although made up of individual parts (electrons, photons, atoms, etc,) have a wave-like manner.

Also, when they have around five or more slits in the experiment, there are beams of light, but every other beam of light is shown. So if there are five slits, there are two or three beams of light shown (I'm not sure if it was two or three, or if the experiment was done with six or more, so you can disregard this part if you want.)

But this is where things start to make no sense...

If you send a SINGLE photon through, you'd expect no interference pattern since there is nothing to interfere with it.

Wrong again!

They send in a single photon at a time, but an interference patter is still shown, EVEN THOUGH THERE IS NO OTHER PHOTONS (or electron, among other things that were not detected) THAT COULD INTERFERE WITH IT.

WTF??!!!

How can a photon be interfered by another photon that is not there?

But, I guess that's quantum mechanics for ya: it makes no Goddamn sense.

I need sleep.

My head's gonna asplode! :p

welcome to post-newtonian physics.


the only science where if you think you understand it you can be sure that you dont.

(unless you have an advanced degree in quantum physics)

It's simple. The photon (or electron) goes through both slits simultaneously, thus interfering with itself.

Quantum mechanics, like life, is weird.
That's probably right, but the detectors only detect a single photon going through a single slit. My dad suggests that the photon has a field of energy that moves through both slits simultaneously.

Another popular theory is that of multiple universes, that a photon in another universe is somehow making the interference pattern with the photon in this universe.

I know of the whole it's in both slits at the same time, but what is confusing me is how. I had to take my mind off the problem by playing some Age of Empires, and now that my mind has cooled off I realized I omitted that part. What's bothering me is how the Hell can a single entity be in two at once? Hmmmmm....

Question - how "static" is the orbital pattern of an electron when it's not being bumped out of an energy level?
Not sure, I'll have to ask.

If you don't understand it, God did it.
I know you're joking, but being a Christian and interesting in noggin' scratchers like this, I can say that is such a boring answer!

Yah, that's all kind of horribly wrong. You should give whomever is teaching you physics a good upbraiding.

Quantum Mechanics: the only discipline where sanity is a detriment.

The photon has gone through both slits. In QM, there is no prohibition against an object being in multiple places at the same time. In fact, in some cases, it's mandatory.

The Flying Spaghetti Monster takes great plasure in confusing scientists.

Yah, that's all kind of horribly wrong. You should give whomever is teaching you physics a good upbraiding.
Please explain. I'm not afraid to be shown wrong, but I don't like it when just state that I'm wrong and never explain.


The photon has gone through both slits. In QM, there is no prohibition against an object being in multiple places at the same time. In fact, in some cases, it's mandatory.
Of course, I'm just wondering how.

Please explain. I'm not afraid to be shown wrong, but I don't like it when just state that I'm wrong and never explain.


Of course, I'm just wondering how.

If you can get your brain around it (try hard!), then you have a bright future in Quantum Physics.

I never did manage it.

Read Timeline, by Michael Crichton. He puts the problem and answer in laymen’s terms.

It works like this; every time a choice is made, the universe it split into separate universes, one for each possible option. These universes exist in constant quantum contact with each other, and when you send photons through the hole, other photons from other universes interact with those photons.

Please explain. I'm not afraid to be shown wrong, but I don't like it when just state that I'm wrong and never explain.


Well, to begin with, if a single slit gave you a beam of light, it wouldn't be thin enough for the rest of the experiment.

You have to at least start with slits that give a diffraction pattern before you can go on and do the rest.

Read Timeline, by Michael Crichton. He puts the problem and answer in laymen’s terms.

It works like this; every time a choice is made, the universe it split into separate universes, one for each possible option. These universes exist in constant quantum contact with each other, and when you send photons through the hole, other photons from other universes interact with those photons.
I've actually been reading Timeline, but I knew about the experiment a long time before I've started reading it. He put it in simple enough terms for me to start thinking about it more clearly, although I can't say I believe the whole multiple universe theory.

Well, to begin with, if a single slit gave you a beam of light, it wouldn't be thin enough for the rest of the experiment.

You have to at least start with slits that give a diffraction pattern before you can go on and do the rest.
Hmmm, good point. However, I'm not sure I read the actual paper close enough. Didn't they already change the slits around with each experiment to make sure it wasn't some other factor making the interference pattern?

Hmmm, good point. However, I'm not sure I read the actual paper close enough. Didn't they already change the slits around with each experiment to make sure it wasn't some other factor making the interference pattern?

Look, you can buy a laser for about ten dollars these days. I suggest you go and actually do the experiment yourself.

Yes, the slits should be changed around, however they are all fungible in the sense that they all emit a diffraction pattern. If they didn't it wouldn't work.

Your problem is that you haven't really grasped wave/particle duality. Once the slits are diffracting, the photons are behaving as a wave. Now the threshold for wave behavior is wave/no wave. As long as it is behaving as a wave, the results you see are exactly what you would expect from a wave. However you have fixed upon the idea that since there is only one photon, then it must show particle behaviour, and hence you get confused.

It really makes sense when you think about it.

But like a wave, it needs an opposing wave to create a diffraction or interference pattern, right? I understand that the photon can act like a wave, but I don't think that waves can interfere with themselves. Or am I completely misunderstanding diffraction?

But like a wave, it needs an opposing wave to create a diffraction or interference pattern, right? I understand that the photon can act like a wave, but I don't think that waves can interfere with themselves. Or am I completely misunderstanding diffraction?

What happens when you pass a wavefront though two diffracting apertures? You get two wavefronts, right? And two wavefronts can interfere with themselves.

As I said, your problem here is that you haven't fully grasped wave/particle duality. A single photon wave can be subdivided into infinity - 1 wavefronts, all capable of self interference.

You would have no trouble with this in a wave tank using a single source oscillator to produce the waves.

But like a wave, it needs an opposing wave to create a diffraction or interference pattern, right? I understand that the photon can act like a wave, but I don't think that waves can interfere with themselves. Or am I completely misunderstanding diffraction?
Once that single wave passes through a slit, only a small part of it passes through. Then it spreads out in all directions, just like making a new wave.

If you have two slits, then two parts of the wave go through, and now it's just like you making two new waves, and these interfere with one another.... I kinda recalled the concept but I do not know whether I had explained it correctly... English ain't my native language anyway...

Read Timeline, by Michael Crichton. He puts the problem and answer in laymen’s terms. Just steer clear of his horribly maligned opinions about climate issues.

Not sure, I'll have to ask.


A thought careened through my head from the OP, and that was one of the first queries in line.

If you have two slits, then two parts of the wave go through, and now it's just like you making two new waves, and these interfere with one another.... I kinda recalled the concept but I do not know whether I had explained it correctly... English ain't my native language anyway...

What he said also. Probably more clearly than I explained it.

Sounds a *lot* like my personality. :eek:

Don't interfere with yourself too much, it may cause a malfunction.


:p

Just steer clear of his horribly maligned opinions about climate issues.

Now, don't unfairly malign the guy. He's an independent thinker. Look at his record about abortion.

Now, don't unfairly malign the guy. He's an independent thinker. Look at his record about abortion.
I won't .... i've enjoyed his presentations of fiction on many an occasion. It's when he attempts (with a lot of help) to represent his fiction as something other than that where he needs a swift kick in the gonads.
I honestly don't know his record about abortion ... is that an inside joke? :)

Don't interfere with yourself too much, it may cause a malfunction.


:p
Truer words never spoken!

~

Once that single wave passes through a slit, only a small part of it passes through. Then it spreads out in all directions, just like making a new wave.

If you have two slits, then two parts of the wave go through, and now it's just like you making two new waves, and these interfere with one another.... I kinda recalled the concept but I do not know whether I had explained it correctly... English ain't my native language anyway...
Well, gosh, that makes a lot of sense. Thanks.

I won't .... i've enjoyed his presentations of fiction on many an occasion. It's when he attempts (with a lot of help) to represent his fiction as something other than that where he needs a swift kick in the gonads.
I honestly don't know his record about abortion ... is that an inside joke? :)

Not really, he was a bit of the darling of the left back then. He simply looked at the evidence and made his own mind up about the efficacy of abortion prohibitions.

You may disagree with him about anthropogenic climate change. But it isn't as if he has put no effort into thinking about it, or that he has been disingenuous about where his position comes from.

That is not to say that he is correct. He well very may be wrong. Only time can tell. But he's not of the same ilk of Hannity et al which will tell any lie which is politically convenient at the time.

You may disagree with him about anthropogenic climate change.Well, that might be an understatement, but yes.
But it isn't as if he has put no effort into thinking about it, or that he has been disingenuous about where his position comes from.Considering how much furor came over his follow-through on his assessment, i'm left to conclude little otherwise.

That is not to say that he is correct. He well very may be wrong. Only time can tell.Well, time, as it is, is now, and scientists who've spent literally their entire lives to study that particular type of phenomenon and related issues can also tell ... and have ... and quite often at risk to their livelihoods.
But he's not of the same ilk of Hannity et al which will tell any lie which is politically convenient at the time.
On that i totally agree.

Considering how much furor came over his follow-through on his assessment, i'm left to conclude little otherwise.

Well that is interesting to me. Because as far as I knew, people never actually criticized the depth of his overview, but rather just the conclusions. I'm willing to change my mind if there is other evidence. In any event, he still probably spent more time thinking about it than 99% of the population, which in itself is noteworthy.

On that i totally agree.

And that's the real point. He's a smart guy. He probably realized that he has more to lose than to gain from this. Whether or not you agree with him, I don't think it is fair tar him with the same brush as the obvious idiots.

Ok. This totally proves I should become some super-brilliant quantum physicist...
That actually made perfect sense to me.

Ok. This totally proves I should become some super-brilliant quantum physicist...
That actually made perfect sense to me.

Well you should. It explains where all the missing matter is. Nobel prize there or something.

That's probably right, but the detectors only detect a single photon going through a single slit. My dad suggests that the photon has a field of energy that moves through both slits simultaneously.

Another popular theory is that of multiple universes, that a photon in another universe is somehow making the interference pattern with the photon in this universe.

I know of the whole it's in both slits at the same time, but what is confusing me is how. I had to take my mind off the problem by playing some Age of Empires, and now that my mind has cooled off I realized I omitted that part. What's bothering me is how the Hell can a single entity be in two at once? Hmmmmm....


Seriously - I actually gave the answer to this already. A 'photon' isn't solid or coherent. What we call 'a photon'... like 'an electron' is just a convenience of speech. Neither term refers to a discrete object - they are concepts... 'an electron' is the statistically most likely orbital pattern for incoherent energy - like 'a photon'.

If you treat photon as 'a mass', you're kind of missing the point. And it doesn't an additional 'field of energy' or 'multiple realities'. It's kind of like asking how can a river flow into two streams at the same time.

You shouldn't think of a photon as an actual physical object, like a tiny marble floating through the air. It's much much too small to be that.
It's more an energy wave which has the greatest probability to be where you're expecting it to be.

A proton is basically a probability wave.
Think of a photo of a water wave that shows regions of high and low intensity (peaks, troughs and flat bits between the waves). The higher the peak (so the higher the intensity), the greater force the wave has for exerting force on nearby objects.

Go that? great.

Now a proton is very much like this snapshot, but the size of the wave at any given point indicates the strength of probability that the electron is located at that point in space. Places where the probability wave is large (thus a 'peak') are points in space where the electron is most likely to be found. 'Troughs' are places where the electron is least likely to be, and the flat bits in-between are zero probability areas - places where the electron can't be.

Thus, when we conduct the light-wave experiment with one slit the interference pattern that appears (the pattern you would intuitively think shouldn't happen) is merely showing you the probability wave of the photon. That's why it ranges out the way it does. And that's why photons can behave like waves or like particles.


Literally, we cannot say exactly where all the electrons within your body are. There is a probability - no matter how small - that one of them might in actual fact be floating around somewhere beyond Mars. So why don't we dissappear and reappear beyond Mars? That's because this only happens on the quantum level not physical level. Such is the joys of trying to understand Quantum physics based upon our knowledge of the physical world.

You shouldn't think of a photon as an actual physical object, like a tiny marble floating through the air. It's much much too small to be that.
It's more an energy wave which has the greatest probability to be where you're expecting it to be.

A proton is basically a probability wave.
Think of a photo of a water wave that shows regions of high and low intensity (peaks, troughs and flat bits between the waves). The higher the peak (so the higher the intensity), the greater force the wave has for exerting force on nearby objects.

Go that? great.

Now a proton is very much like this snapshot, but the size of the wave at any given point indicates the strength of probability that the electron is located at that point in space. Places where the probability wave is large (thus a 'peak') are points in space where the electron is most likely to be found. 'Troughs' are places where the electron is least likely to be, and the flat bits in-between are zero probability areas - places where the electron can't be.

Thus, when we conduct the light-wave experiment with one slit the interference pattern that appears (the pattern you would intuitively think shouldn't happen) is merely showing you the probability wave of the photon. That's why it ranges out the way it does. And that's why photons can behave like waves or like particles.


Literally, we cannot say exactly where all the electrons within your body are. There is a probability - no matter how small - that one of them might in actual fact be floating around somewhere beyond Mars. So why don't we dissappear and reappear beyond Mars? That's because this only happens on the quantum level not physical level. Such is the joys of trying to understand Quantum physics based upon our knowledge of the physical world.

Might want to spellcheck your protons and photons...

did you remember to carry the one?

maybe you should recalibrate the deflector dish :p

Don't forget that the negative power coupling has been polarized, and needs to be replaced.

Might want to spellcheck your protons and photons...
what's an 'h' or 'r' between friends?

Thanks guys, now I can sleep.

I knew this would be the right forum to go to!

Might want to spellcheck your protons and photons...

Really, given your first response to this, you probably should put the arrogance checker on.

Really, given your first response to this, you probably should put the arrogance checker on.

Sand in your knickers?

I really don't see where this comes from, otherwise.

DH gave a great response, but some of his(?) photons turned into protons in the process. I subtly pointed that out... and I'm not sure why that should get anyone's panties in a bunch... not even DH.

I gave a digest version of the uni answer. I could have been more textbook, maybe - but that's not the voice I wanted... that's not the perceived audience. So.. what exactly was the problem again?

I gave a digest version of the uni answer. I could have been more textbook, maybe - but that's not the voice I wanted... that's not the perceived audience. So.. what exactly was the problem again?


The actual answer, of course, is that 'a photon' is only a probability, not a lump of 'stuff'.

I hardly think that this is the 'digest version' of the 'uni' answer. Doubly so since probability has nothing to do with the case in hand.

On the other hand, you probably can't tell the difference.