Examining the Slit Experiment

[KickAssClown]

Taken from the light particle duality article

Originally Posted by KickAssClown

As I have placed as objection in the past, why must I accept that the photon, electron, etc went through the slit at all?

Originally Posted by CraigD

This seems an easy question to answer: because when you cover the slits, no photons, electrons, etc. appear on the other side at all.

That would seem to be the easy answer, but if you ask the question of if the barrier is massed, and mass is 90% empty space, then why doesn't the photon merely pass through the barrier?

This of course is without getting into the whole dual nature of the barrier itself or the absorption of the barrier.

What I mean is that one can not simply neglect the influence of the barrier in the experiment. It has mass, and energy. It curves the trajectory of the photon/electron/etc. It has a measurable effect on the surrounding space. So once again, I must ask why must I accept that the photon passed through the slits? Also in the case of a closed barrier, why must I accept that the photon is still contained within the experiment area?

[Boerseun]

Well, simply put, if you close the slits, nothing goes through. This is easy enough, a torch and your hand should do the trick.

How, and why, or rather, why not the photon passes through the mass barrier, when that mass 99% empty space, is a matter for optics. The slit experiment is about light exhibiting interference patterns under certain conditions, putting the 'wave' part of light's 'wave/particle' duality on display. And the freaky thing is that a single photon will interfere with itself. Now that's just plainly weird.

What I want to know, seeing as we're discussing this particular experiment, is how on earth do they guarantee that a single photon was released in order to produce the results? Who counts photons? How do you count photons? I think there's a lot to the physical structure and properties of light that we don't fully understand yet. I'm actually of the opinion that light is completely different than what we think it is. But that's just me.

[freeztar]

I suppose they have a highly callibrated photometer for measuring photon(s)...

I agree with you though Boer...I think light is something entirely different than we think and it will be a long time, if ever, before we fully understand it.

[pgrmdave]

So once again, I must ask why must I accept that the photon passed through the slits? Also in the case of a closed barrier, why must I accept that the photon is still contained within the experiment area?

Well, when we set up the experiment, we have something that produces photons, the slit, and a detector. When we have a slit present, we are able to detect the photon on the other side. When we don't have a slit present, the photon is not detected. Clearly the presence of the slit allows the photon to travel from the producer to the detector. Perhaps there are reasons other than the possibility that the photon travelled through the slit, but then why would the presence of a slit have an effect? Why the photon doesn't travel through the barrier doesn't really have any bearing on the question - the fact is that it stops the photon.

[Qfwfq]

Originally Posted by KickAssClown

That would seem to be the easy answer, but if you ask the question of if the barrier is massed, and mass is 90% empty space, then why doesn't the photon merely pass through the barrier?

Sure, especially if you use a barrier made of glass!

Originally Posted by pgrmdave

Perhaps there are reasons other than the possibility that the photon travelled through the slit, but then why would the presence of a slit have an effect?

Excellent! This is exactly the matter of the whole issue: If we hypothecically consider that the particle went through one of the slits, then why does the other have any effect?

Essentially, what the experiment shows is that there is something non-local about how the outcome is determined for each single particle. Quantum formalism describes this with great success but we don't understand exactly how the observable outcomes are determined.

Originally Posted by Boerseun

What I want to know, seeing as we're discussing this particular experiment, is how on earth do they guarantee that a single photon was released in order to produce the results? Who counts photons? How do you count photons?

Basically, knowing the nature of the source and the typical duration of each emission, it's enough to have few enough emissions per unit time so that, given the length of the apparatus and therefore the time of transit, the great majority of them won't be overlapping. It's a statistical consideration. Today there's a variety of possible techniques for counting photons, when I was in fourth-year lab we used an old photomultiplier tube cooled with liquid nitrogen and a spectrometer to cast away most of the "noise" i. e. triggerings not due to a photon coming in. Technology does however offer some more refined things today.

Originally Posted by Boerseun

I think there's a lot to the physical structure and properties of light that we don't fully understand yet. I'm actually of the opinion that light is completely different than what we think it is. But that's just me.

It isn't just a matter of light, it's about anything. Quantum formalism describes the way reality is, when things are in a coherent state.

[LaurieAG]

Originally Posted by Qfwfq

Essentially, what the experiment shows is that there is something non-local about how the outcome is determined for each single particle. Quantum formalism describes this with great success but we don't understand exactly how the observable outcomes are determined.

Hello Q,

If a photon is a particle that orbits in a very small radius around its center while moving in a fixed direction (like an electron orbit), this width, the width and depth of the slits, and the actual direction of the spin (relative to its proximity to either side of the slit) would have to be taken into consideration in any experiment, conceptual, quantum or otherwise.

A clockwise orbiting photon would be blocked by the barrier while an anti clockwise orbit would deflect inside the slit (on the slits side) if they were both shot at the slit from the exact same location (i.e. within one radius length of rotation of the slits edge).

If your measuring equipment (or experiment) couldn't determine, or didn't consider the radius of rotation of the photon the result would appear uncertain. This is also consistent with the photon being a particle which produces a wave when you plot the forward motion of its orbit over time. (i.e. the particle is now (no orbit considered) and the wave is the orbiting particles path over time).

[Erasmus00]

Originally Posted by Boerseun

What I want to know, seeing as we're discussing this particular experiment, is how on earth do they guarantee that a single photon was released in order to produce the results?

This is actually a topic of much debate in the world of quantum optics. However, we could just as easily do this experiment with electrons, where it is much easier to deal with the particle nature.
-Will

[KickAssClown]

Well. I suppose that helps to clarify the details of the experiment, however it does not statisfy my sense of reasoning.

I understand and accept that the medium the photon is passing through/by/around/under/over/etc has an effect. Elementry, matter bends the path of light through space-time.

What I am questioning is whether or not the interpertation of the outcome of the experiment is correct, within reasonable certainty. There are, in my mind and observation, many possible explinations for the experimental outcome.

In my own view, I do not see why it is not possible, if not reasonable, that the photon does not merely leave the detecting area when the slit is closed. Following the path of least resistence/action. For that matter why does the interferance pattern have to be the result of the (same) photon impacting the surface of the detector?

I primarily think of things like Faraday cages, and other similar electromagnetic phenomena in this regard. Like I said, how can one neglect the matterial barrier, or the matterial observation equipment in this experiment?

As I have attempted to explain previously on this site, what if fundamental matter is point-like, and without mass-energy. In and of itself? What if mass-energy is the measurement of a ray between fundamental matter?

This question is non-trivial. If photons interact only approximately to how we would think and calculate then it is possible that the whole results of the experiment are thrown into question. Whether it is done with a photon or an electron.

Eitherway, assumptions are being made in the interpertation of the data which may not be entirely justified. Common-sense, sure. Scientifically, logically and mathematically sound, maybe not.

[Drum]

Originally Posted by KickAssClown

Well. I suppose that helps to clarify the details of the experiment, however it does not statisfy my sense of reasoning.

I hope I am not intruding here. This is my very first post and I don't know a lot about Science or Maths .... but perhaps I may be able to go a little way towards satisfying your reasoning. In your original thread #1 you had a problem with the barrier.

Originally Posted by KickAssClown That would seem to be the easy answer, but if you ask the question of if the barrier is massed, and mass is 90% empty space, then why doesn't the photon merely pass through the barrier? ......

Just for the moment forget about the photon and replace it with an electron. Electrons have negative charge .. The barrier is made from cardboard, steel or anything else you like and it doesn't matter if it is 99% space. The fact is that the barrier is a substance made of molecules locked together within an electron field. It is stable, it has the correct electron count in its shells around the positive protons and it does not want any more. The charge is balanced. You are also made of the same electron binding. Negative charges repel. This is why you cannot walk thru a wall, when you get close, the wall's negative electron field repels you as much as your negative electron field repels the wall, not the fact that the wall is solid, nor that it is 99.999% space. A bullet can tear through a cardboard wall because its electron field is tighter and 'locked' in a more stable 'matrix'. It has enough acceleration (increased mass) to literally overcome the negative repulsion and breaks the electron bonding. Remember, this is not Science, just rough understanding. The next thing in your thread was that you cannot ignore mass

Originally Posted by KickAssClown What I mean is that one can not simply neglect the influence of the barrier in the experiment. It has mass, and energy. It curves the trajectory of the photon/electron/etc. It has a measurable effect on the surrounding space.

Unfortunately, in Quantum Mechanics you do have to ignore mass. The mass that effects the curvature of space is to do with Classical maths. That is, the maths of Newton and Einstein. Einstein's principle of equivalence states, and very elegantly proves, that gravity and acceleration can be considered as one and the same thing. Lets not go there yet. Very, very basically classical maths says that to leave one location and arrive at another you need to travel a trajectory that can be calculated. In other words, you know where and when you are at any particular point and you can prove it with math. This enables us to build tall buildings and travel faster than the speed of sound. It ensures that commercial flights arrive at their destinations on time. It governs our Macro world.

Quantum mechanics says that if you want to know, with any degree of accuracy, the location at any point you cannot know with certainty the trajectory taken because all possible trajectories have a probabilty of being correct. Lets not go there yet.

You cannot introduce gravity (acceleration) into quantum mechanics. It turns into nonsense. Sounds weird I know, but without our grudging acceptance of Quantum mechanics there would be no computers, no smoke detectors, no internet and so on. We have to live with it.

These two forms of mathmatics do not agree and yet the results of QM never break Einsteins rules of relativity. String theory bridges these two, but because it can never be proven it is relegated to an Hypothese along with religion etc

We are now talking about QM only: You shine a torch on the dual slits and the hot filament inside the bulb ejects trillions of electrons at much less than the speed of light, many of which strike the first barrier and each electron gives off one photon of light. They take no further part in the experiment. Those that pass thru the slits are unaffected by the negative charge of the barrier. (Trust me) They strike the second barrier in a bar pattern and each electron gives off one photon of light which enables us to see the pattern.

Of course its obvious (or is it) that the trillions of electrons pouring through the two slits are colliding and jostling each other and therby form a bar pattern as they strike the wall.

We close one slit. Now all the electrons have to pass through one slit only and of course there is no bar pattern, just a blur on the wall. This too, is obvious.

So now we slow the electron emission rate to only one every ten seconds. (very easily done) Now there can be no jostling and elbowing for position. Each electron has ten seconds to himself to get to the wall. With only one slit open, and after recording where each electron strikes with a geiger counter, the same blur pattern is built up slowly but surely. This too, is obvious.

Now we are entering the really weird part of QM. We open the second barrier and allowing each lonely electron 10 seconds to arrive at its destination we set the geiger counter to record and head of to make a brew (coffee). When we get back after a cigarette and a brew the geiger counter gleefully tells us that the bar pattern is back.

How can this be ?? The electron had to go through one or other of the slits, there were no others electron to create wave interference ?? What the fuk is going on. One particle cannot create a wave. If the particle is a wave then what the fuk is it waving with ?

And there you have QM in a very simple nut shell. Everything is a wave. How does it wave ?

Turns out it is a very special wave..... not like a water wave or tsunami, nor a mexican wave like at the football. Its a probability wave.

Whats a probability wave. QM tells us that prior to striking the second barrier the electron particle/wave had a probability of going through either slit in the first barrier. In other words there are 2 paths, each with a probability of 50%. QM says that each probability is a possibility.... further ... if its a possibility it WILL happen. In other words it must always equal 100%.

Remember you can never know 100% trajectory if you know the arrival point. In other words the particle/wave went through both slits with a probability of 50% and waved with itself. True. If there were 3 slits it would have gone through all 3 with a 33.333% probability. and so on if there were 4, 5 .... remove the first barrier and you have an infinite number of paths each with a probability.

If you put the geiger counter on one of the slits to determine its path by detecting it (or not detecting it) you simply change the arrival point to that location and from there to the wall it travels with 100% known trajectory and forms the blur again as opposed to the pattern. The same as if there was only one slit.

Quantum mechanics says that all matter has this wave particle duality. This means that prior to observation/interaction all things have a probability of being absolutely any where in the universe. Another way of thinking about it is that the particle is spread like a giant elastic sheet throughout the whole universe, thinnest where the probablity is least, thickest where its most probable. The instant you interact with the observed particle its location is now known 100% and therefore its probability of being anywhere else collapses to zero. This really means that the particle could have been in a distant galaxy, of course with a very very very minute extremely small probability immediately prior to your observation

In general, the highest probabilities for anything are where they are most likely to be. Thats why life always behaves as we expect, The odd hiccup, such as a Tyranosaurus Rex, appearing in front of your eyes for a nano-second is passed of as 'I must have been seeing things'. But if you set out to walk through a wall and you keep at it for an enternity, no matter that the probability is an infinity to one... given an infinite numbers of tries you will appear on the other side at least once. Wow, I am very sorry if this post has gone on too long... Remember its only a rough explanation and I hope it helps

cool bananas ...... drum

[KickAssClown]

I quite enjoyed your explanation, Drum. It hit some of my points of contention, but missed a few others. Obviously missed two of my major points of contention. Kudos though.

Originally Posted by Drum

Just for the moment forget about the photon and replace it with an electron. Electrons have negative charge ..

Drum, I know you haven't been here at hypography long enough to necessarily read my other posts regarding the nature of mass-energy, space-time, charge and matter.

Consider a simple correspondence fact about the photon and electron. They both have mass-energy and thus are identified as forms of matter. The difference between them is minor when you go into it far enough. They both have net charge, mass-energy, spin, etc (same property-types).

Now consider that the detector, the slits, and the barrier are all composed of material, that is they all have the properties of net charge, mass-energy, spin, etc.

By identity the electrons, photons, neutrons, and protons have no formal property differences from one another. That is they all have the same properties, though different variances in the values of those properties.

Why is this all important? Well if we conjecture for a moment that our emitted particle, box, barrier, slit and detector are a homogeneous soup of matter varying only in values of properties, how are we to discern that the particle we shoot is the particle we catch?

Which I surmise in my question of "why must I accept that the particle went through the slits at all?"

Classical physics sees the particle as one single piece (or collection of tightly held pieces); Quantum physics retains but refines this picture of the particle. I question the very validity of that model.

What I am questioning is the results of a material experiment within which I believe that certain key factors are being neglected, such as the very structure of matter at it's fundament.

Neither Classical physics, nor Quantum physics give a satisfactory explanation (theory) of matter. Here is a challenge. Give me two seperate theories of matter. One classical and one quantum. Preferably from the standard model.

Thanks for listening and I look forward to your reply.

-sign
The Klown.