Exploring the 2 Slit Experiment: Particle Deflections and Gravity's Role

In summary, the two slit experiment shows that interference patterns can be created when light shines through two small slits spaced a certain distance apart. It is possible that the particle's momentum or temperature changes after it goes through one of the slits, causing the interference pattern to disappear.
  • #1
swhite44
13
0
2 slit, double slit, two slit

I saw a previous topic where someone asked if anyone has tried the 2 slit experiment with bigger objects (not Bucky balls) like sand or golf balls, but it seems not?
I wondered if the diffraction patterns could simply be a result of the particles deflecting off the edges of the slits?
Also what is the nature of the source of the particles, is it a single point source of light or electrons that 'sprays' across the area of the 2 slits?
And how are the slits cut in the material? With sharp flat edges or angled?
Maybe double slits in a single layer gold leaf film would be good to try?

Perhaps gravity could be the force to propel sand or some other macro particles through slits: just pour it down in a stream. I guess the size/velocity ratio might disallow the necessary deflections required to make a pattern though?
 
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  • #2
swhite44 said:
2 slit, double slit, two slit

I saw a previous topic where someone asked if anyone has tried the 2 slit experiment with bigger objects (not Bucky balls) like sand or golf balls, but it seems not?
I wondered if the diffraction patterns could simply be a result of the particles deflecting off the edges of the slits?
Also what is the nature of the source of the particles, is it a single point source of light or electrons that 'sprays' across the area of the 2 slits?
And how are the slits cut in the material? With sharp flat edges or angled?
Maybe double slits in a single layer gold leaf film would be good to try?

Perhaps gravity could be the force to propel sand or some other macro particles through slits: just pour it down in a stream. I guess the size/velocity ratio might disallow the necessary deflections required to make a pattern though?

the slits can be staggered in space/time and interference can still be made to work...
 
  • #3
Staggered in space/time, doesn't that imply it's not an interference pattern they're seeing?
It seems like stretching an elaborate theory around a false assumption.

Pity someone doesn't try the experiment with a table tennis ball shooting machine, they might see similar patterns due to balls glancing off the edges of the slits.
 
  • #4
Hi swhite44.
No that wouldn't work, the double slit experiment showing a diffraction pattern is all about a particle 'interfering with itself' 'as long as it can't be determined which slit it went through'
A heavy object being deflected by a sharp edge would certainly be identified as going through one or the other slit and therefore the diffraction pattern wouldn't appear, just as it disappears for a tiny particle which you observe too closely
 
  • #5
Yes I know the interpretation of the results of the experiment is that the pattern is a diffraction pattern caused by quanta somehow interfering with themselves, but maybe the pattern has some more rational cause?
 
  • #6
This 'somehow interfering with themselves' is mind boggling
In order to try to understand how this can possibly happen, it has been tried to 'look at what happens' (does the particle goes through this slit, or the other one ? or both ?)
Every time this is done, there is no longer any diffraction, you are back to the same effect you would expect with tennis balls or whatever 'macro-particle'
This is the key point and the answer about 'has it been tried with bigger objects' ?
yes it has, in fact it has been tried a lot 'not to do so' :)
 
  • #7
So whatever they do to detect which slot the photon goes through, removes the wave property?
Can't they fire charged particles through some gas so they leave a trail?
Better to use a less invasive detection method.
 
  • #8
No, as you said *whichever* method being used
it goes beyond the fact that someone looks at it, the same thing applies to the involved system regardless of the experiment.
As soon as something is recorded, it is over.
So, if the particle bounces over one slit wall with enough force that it had any impact on said wall (increased momentum/temperature/whatever that makes it a measurably different wall after than before) then it is determined that the particle went through this one slit, and no interference will show, simply because there is no interference any more: the particle went through this, or this slit and that is the end of it.
On the other hand, if there is no way to tell, not because our measurement apparatus isn't sensitive enough, but because there is physically no way to tell at all, then, and only then, will the interference pattern appear.
 
  • #9
Doesn't make sense, unless the method of measuring or recording which slit the particle goes through changes the properties of the particle.
Maybe the photon is embarrassed to be a just a mere formless wave, so it pretends to be solid matter if someone is watching?
 
  • #10
Indeed, the measuring changes the properties of the particle, this is Heisenberg's uncertainty principle, except it goes far beyond 'someone watching' and goes straight through the actual individual existence of said properties.
 
  • #11
That's pretty poor, can't they improve their measuring technique?
It's like measuring the speed of Nadal's serve in the French open today and saying 'that serve was 90 miles an hour, but the radar knocked the ball out of court so it's not counted'.
 
  • #12
There is no 'they' :)
This has nothing to do with measurement technique and everything to do with how things behave at the fundamental level, that is, as far as I know, the universe itself doesn't know what was the exact parameters of said service.
 
  • #13
or may its like saying i don't understand what your saying so you must be wrong and i can't believe how poor your answer was. or maybe its just like being a troll?
 
  • #14
of course you could just do the maths?
 
  • #15
You lost me there.
If measuring which slit a particle passes through removes the wave quality of the particle, then there's something intrusive about the measuring technique isn't there?
So 'they' who do the measuring should devise a more sneaky subtle technique.
It's as if the particle knows it was tracked?
 
  • #16
hey, this is a fanciful question. this experiment, if actually carried out at all, wouldn't give any "measurable" and satisfactory result. the diffraction effects would be so small (you can calculate it using de Broglie hypothesis) that it cannot be measured. furthermore, the two-"slit" experiment requires that you have an horizontal continuous array of tennis ball shooter as ball-quanta sprayer. and then there is gravity... with all this, I don't think it's worthwhile to do this now. perhaps the next century will have the proper technology to do that.
 
  • #17
The particle does not have a wave behaviour any more than it has a 'regular particle' behaviour
It's a particle, and it behaves differently than a tennis ball
Measurement changes the outcome of the experiment, but the experiment carries on without anyone watching anyway,
that is, in order for the particle to take a definite path (through one slit or the other) it would 'leave a mark' regardless of someone putting an apparatus to check this mark.
If the particle interacts with any slit in anyway that is *physically* meaningful, then the particle went through that slit, and that is is, no confusion, no interference.
If on the other hand whichever path the particle took is absolutely untraceable, as in, 'not even the universe itself as any way to tell', then you can conclude, in a way, that it went through both slits, and the interference shows.
Of course it is more complicated than that, one particle does not, in fact, interferes with itself, but if the conditions of experiment are right, then, over time, one particle after the other, the interference pattern will show.
the interference happens lower, at the probability level.
 
  • #18
until your grasp that it is not the MEASURING that collapses the wave function but the information becoming available that collapses it you have no chance of grasping this, if you truly are trying to. It has already been mentioned that there are variations to the experiment that demonstrates that it is NOT the measuring that collapses the wave but the information that could lead to knowing which slit it went through being available that collapses it. See the Delayed choice quantum eraser.
 
  • #19
swhite44 said:
You lost me there.
If measuring which slit a particle passes through removes the wave quality of the particle, then there's something intrusive about the measuring technique isn't there?
So 'they' who do the measuring should devise a more sneaky subtle technique.
It's as if the particle knows it was tracked?
As mentioned before, it is not an experimental issue. Each fundamental interaction is symmetric: If object A influences object B, then B also influences A with the same strength. If your electron or whatever should influence the environment enough to measure its path, the environment has to influence the electron enough to disturb the interference pattern.
 
  • #20
actually i believe the particle does interfere with itself. The point being that if the path cannot be determined then the particle takes every possible path simultaneously. But only one path is collapsed when it hits the detector.
 
  • #21
Rajatmo, no I meant has anyone tried it with sand or balls just to see if there is a dispersal pattern, due to the objects glancing off the edges of the slits. Not to see if table tennis balls interfere with themselves and produce a diffraction pattern.
 
  • #22
swhite44 said:
You lost me there.
So 'they' who do the measuring should devise a more sneaky subtle technique.
It's as if the particle knows it was tracked?

Yes, it really is "as if" the particle knows that it's being tracked.
However "It's as if" does not mean "It is". We're pretty sure that whatever is going on, the particles aren't really consciously conspiring to produce weird experimental results and that we can defeat their wicked conspiracy by being more sneaky subtle than they are.

Of course, now I'm inviting the question "What really is going on?". There are a half-dozen more or less well-accepted possible answers, collectively known as "interpretations" of QM. No one has been able to come up with experiments or math to conclusively confirm or deny them, so which one you prefer is partly a matter of personal taste, partly a matter of which is most convenient for the problem you happen to be working on at the moment.
(BTW, "The particle knows it is being tracked" is itself an interpretation, just one that nobody takes seriously).
 
  • #23
>> Of course, now I'm inviting the question "What really is going on?". There are a half-dozen more or less well-accepted possible answers, collectively known as "interpretations" of QM.

Yes I read about this after reposting a Facebook thing saying something like 'according to scientists we live in a world of all possibilities'.

But after reading a bit, I'm thinking 'people look back on how dopey pre-Copernicans were to believe the Earth was the centre of the universe, and before that how moronic people were to think the world was flat. But how comparatively ludicrous is the multi-world theory, that infinite worlds exist covering every possible outcome that ever could have happened?'

Maybe there's a simple reason for that 2 slit diffraction pattern.
 
  • #24
swhite44 said:
Rajatmo, no I meant has anyone tried it with sand or balls just to see if there is a dispersal pattern, due to the objects glancing off the edges of the slits. Not to see if table tennis balls interfere with themselves and produce a diffraction pattern.

I don't think anyone would ever think to do it (why don't you do it yourself?) but, there are some subtle things to account for the dispersal pattern that indeed will show up. you can imagine that yourself. and, nowadays, the theory of light as EM wave is largely replaced with the probabilistic theory. so, what you must "measure" from that type of experiment is the probability of hitting some balls on a certain part of the screen. now, physically, that wholly depends on the "randomness" of the shooter machine. All in all, you can't have any satisfactory quantum analog here.
 
  • #25
swhite44 said:
But how comparatively ludicrous is the multi-world theory, that infinite worlds exist covering every possible outcome that ever could have happened?
The multiple worlds interpretation is nowhere near ready to be dignified with the term "theory"; compared with (for example) the theory of gravitation, the theory of relativity, or the theory of evolution, MWI is mere speculation. It's one of those interpretations that gets a lot more attention from the popular press than from practicing physicists, because it's cool and catchy and it's easy to write interesting non-technical articles about it.
Maybe there's a simple reason for that 2 slit diffraction pattern.
There is. The quantum mechanics that predicts this behavior isn't terribly complicated, and we were happily applying very similar math to light waves for more than a century before quantum mechanics came along.

The problem isn't that quantum mechanics is hard; two years of college-level math is enough to tackle QM, and there are a lot of things that are harder than that. The problem is that some of the conclusions of QM are weird and counterintuitive, yet we have a ton of experimental evidence that says that the universe really does work in this weird way.
 
  • #26
swhite44 said:
Doesn't make sense, unless the method of measuring or recording which slit the particle goes through changes the properties of the particle.

The only way to measure the wave, is to make the wave collapse. So if you collapse it at either slit, then you don't have it progressing to wall where pattern is.

Though I wonder. Is there anything like Cherenkov radiation that could be observed without collapsing the wave?


I think considering the waves as particles, might make mathematical sense, but the idea is wrong. The wave does not collapse into a particle, it collapses into the electrons of the atom it hits. And those electrons are waves. From start to finish there is no particle.
 
  • #27
but its not just electrons the experiment has been carried out with.
 
  • #28
I think KRD means the energy of the wave collapses into the electron it hits, not that the fired particle was an electron?
 
  • #29
boffinwannabe said:
but its not just electrons the experiment has been carried out with.

It was originally done with light. Supposedly it's been done with buckyballs. The electron one is the most interesting in that the results are unambiguously weird. The single electron is clearly shown to interfere with itself.
 
  • #31
I'm thinking, it can be measured at each slit, without collapsing the wave.

If the slits are in a cold vacuum - a very cold vacuum. The wave or particle, as it passes through the slit - say if the walls of the slit are lined with an inductor - they might be able to register the passing "particle" without collapsing it.

Or. Instead of slits, have pieces of transparent materials in the slits - some kind of crystal - might be possible to measure the wave passing through the crystal, again without collapsing it.

I think there's a few variations you could do without collapsing the wave.

I would still say you'd see the wave pass through both slits simultaneously. The results would be interesting to look at.

If you had all the stuff for really cold nano-engineering, you could nudge a buckyball into some slits - the slits could be the legs of nano-transistors - and then zap it with a photon and see what the legs register.
 
  • #32
dont forget its not a real wave, its a probability wave, you will never see the wave. Also there is no way to find its position without collapsing the wave, this is the whole point. No matter how clever your technique and apparatus, knowing its position no matter how you do it collapses the wave, else there would nothing to measure.
 
  • #33
boffinwannabe said:
dont forget its not a real wave, its a probability wave, you will never see the wave.

Well the waves look very real when you see the interference pattern.

Also there is no way to find its position without collapsing the wave, this is the whole point.

Yep, that's what I would have thought before. But now I think there could be many ways you could measure the wave without collapsing it. Polarising the electron, then letting it pass under an array of plates - an inductance pattern should (or could) emerged - without the wave collapse.

No matter how clever your technique and apparatus, knowing its position no matter how you do it collapses the wave, else there would nothing to measure.


I say...let's try all the clever techniques, and then only after we've failed can we say they didn't work.
 
  • #34
it might look real but its a probability wave, its not a physical wave.
 
  • #35
boffinwannabe said:
it might look real but its a probability wave, its not a physical wave.

If you drop a pebble in a still lake - and watch the ripples. That is precisely the same process.

And before you come back and tell me I'm wrong, I want you to think about it.
 
<h2>1. What is the 2 slit experiment?</h2><p>The 2 slit experiment is a classic experiment in physics that demonstrates the wave-like behavior of particles. It involves shining a beam of particles, such as electrons, through two parallel slits and observing the resulting pattern on a screen behind the slits.</p><h2>2. How does the 2 slit experiment demonstrate particle deflections?</h2><p>In the 2 slit experiment, particles are expected to pass through the slits and create two distinct bands on the screen behind them. However, the actual pattern observed is a series of alternating dark and light bands, indicating that the particles are being deflected by some unseen force, which is later revealed to be wave interference.</p><h2>3. What role does gravity play in the 2 slit experiment?</h2><p>Gravity does not play a significant role in the 2 slit experiment. The experiment is typically conducted on a small scale, where the effects of gravity are negligible. However, gravity does play a role in the overall understanding of the experiment as it is a fundamental force that affects all particles in the universe.</p><h2>4. Can the 2 slit experiment be applied to larger objects?</h2><p>Yes, the 2 slit experiment has been successfully applied to larger objects, such as buckyballs (soccer ball-shaped molecules). This further supports the wave-particle duality of matter, where all objects, regardless of size, can exhibit both particle and wave-like behavior.</p><h2>5. What are the implications of the 2 slit experiment on our understanding of the universe?</h2><p>The 2 slit experiment has challenged our traditional understanding of the behavior of particles and has led to the development of quantum mechanics, a branch of physics that explains the behavior of particles on a microscopic scale. It also suggests that the universe may be fundamentally probabilistic, rather than deterministic, and that the observer can influence the behavior of particles through the act of measurement.</p>

1. What is the 2 slit experiment?

The 2 slit experiment is a classic experiment in physics that demonstrates the wave-like behavior of particles. It involves shining a beam of particles, such as electrons, through two parallel slits and observing the resulting pattern on a screen behind the slits.

2. How does the 2 slit experiment demonstrate particle deflections?

In the 2 slit experiment, particles are expected to pass through the slits and create two distinct bands on the screen behind them. However, the actual pattern observed is a series of alternating dark and light bands, indicating that the particles are being deflected by some unseen force, which is later revealed to be wave interference.

3. What role does gravity play in the 2 slit experiment?

Gravity does not play a significant role in the 2 slit experiment. The experiment is typically conducted on a small scale, where the effects of gravity are negligible. However, gravity does play a role in the overall understanding of the experiment as it is a fundamental force that affects all particles in the universe.

4. Can the 2 slit experiment be applied to larger objects?

Yes, the 2 slit experiment has been successfully applied to larger objects, such as buckyballs (soccer ball-shaped molecules). This further supports the wave-particle duality of matter, where all objects, regardless of size, can exhibit both particle and wave-like behavior.

5. What are the implications of the 2 slit experiment on our understanding of the universe?

The 2 slit experiment has challenged our traditional understanding of the behavior of particles and has led to the development of quantum mechanics, a branch of physics that explains the behavior of particles on a microscopic scale. It also suggests that the universe may be fundamentally probabilistic, rather than deterministic, and that the observer can influence the behavior of particles through the act of measurement.

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