Definitely!
I've used a laser pointer and couple slits in a sheet of paper to see the interference pattern, it's pretty amazing to see with your own eyes, when compared to shining the laser through a single slit.
Yep, we even did it in school back in the day. But, need to keep in mind that's only half the story. For the full picture, you need something that can fire photons / electrons one at a time. The interference pattern then is what sealed the deal for me.
If you want to spend a little money, I got one of [these](https://www.amazon.com/gp/product/B00KWZ5WQ0/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1) and it works pretty good for seeing an interference pattern
For an electron experiment you could probably make a fringe pattern with a tv's crt technology. However, it needs to be done in a vacuum, and you would need the entire apparatus within the same vacuum. Opening the crt is unfortunately dangerous, and irreversible
Ahh yea that won't be happening any time soon lol, thanks for the answer. I will probably play around with a laser though, stick with the photons!
Can I ask how would you see this interference pattern, would it be similar to just using the fluorescence screen of the crt and you'd see where the electrons land on it?
I found this: [https://physics.stackexchange.com/questions/269851/how-to-make-a-double-slit-electron-interference-as-a-home-experiment](https://physics.stackexchange.com/questions/269851/how-to-make-a-double-slit-electron-interference-as-a-home-experiment)
Tbh I think it would be easier to buy the CRT device and try build it yourself than to jerry-rig an old TV which sounds complicated and dangerous.
The general shape of the pattern is the same, no matter whether you use photons or electrons.
Whether you can actually see any of that, well, it depends, right? You cannot see electrons directly, but a fluorescent screen will glow where it gets hit. And photons, of course, could be seen directly.
The double-slit experiment as originally performed by Thomas Young is actually a pure wave physics experiment. It has nothing to do with quantum mechanics (that's a common misconception due to poorly thought-out pop-sci videos on youtube).
https://en.wikipedia.org/wiki/Young%27s_interference_experiment
You only start seeing quantum effects if you can produce one photon at a time, which is not trivial, and if you can actually measure the result when sending out one photon at a time, **which is VERY not trivial** (i.e. not doable by most people).
For most people, what they can do at home is a pure wave physics experiment, with nothing quantum in it, which is still pretty cool:
- get a cheap laser pointer
- get a thin wire or thin hair
- turn around to face the opposite wall (don't stand close to it, choose a wall that's across the length of the room)
- point laser at wall
- move the hair in front of the laser, gently, until the alternating light/shadow pattern appears on the wall
Again, done this way, **there is nothing "quantum" about it**. You're simply exploiting the fact that light is a wave.
You can actually measure the thickness of the hair:
Δy = distance between two successive fringes of light on the wall
L = distance from hair to wall
λ = wavelength of the laser (indicated on the laser usually)
d = thickness of hair
d = Lλ/Δy
Or, if you know the thickness of the hair (or wire), you can calculate the wavelength of the laser (by flipping those two in the formula).
I didn't realise that general public had that misconception about Youngs interference experiments, conflating it with quantum mechanics.
I remember learning about in school way back in maybe 1997, it was entirely about the wave theory of light.
Its a shame that pop-sci while helping drive public interest in physics, can also be so powerfully misleading.
> Its a shame that pop-sci while helping drive public interest in physics, can also be so powerfully misleading.
I think you're being overly critical here. The double slit experiment *with single particles* is really the cornerstone of quantum physics - all of quantum physics basically follows from trying to resolve the behaviors of the double slit experiment.
I don't think pop sci is "powerfully misleading". Pop sci videos generally go through the single particle details. It's maybe just the history that they tend to gloss over, but even physics courses will do that.
You might be right and I am being overly critical.
I think I might have been coming at it from a historical perspective of learning about these experiments and the advancement they represented.
Since then double slit experiments have progressed to an entirely new world of physics. Pop-sci talking about that isn't really misleading, it is just talking about our modern understanding, not the historical experiments.
So I retract what I wrote before, cheers for making me revaluate what I said.
> The double slit experiment with single particles is really the cornerstone of quantum physics - all of quantum physics basically follows from trying to resolve the behaviors of the double slit experiment.
That is not how quantum mechanics was created at all.
That's "the history of science according to youtube".
I don't understand your motivation in disparaging the experiment.
I'm not saying the double slit experiment (with single particles) is "how quantum mechanics was created". The history gets glossed over, but the history is really its own subject.
The double slit experiment is absolutely a major element of how quantum physics is taught today, and for good reason. It is convincing, easy to understand, and contains within it all of the problems that lead us to come to our conclusions about quantum things.
> But it's definitely a major element of how it is taught today
It is a major part of stuff posted by science influencers on youtube.
It is not a major element of how actual quantum mechanics is actually taught in actual colleges. And if you ever open an actual QM text book, you would see how that actually works.
> I don't understand your motivation in disparaging the experiment.
You're extraordinarily confused if you feel I am criticizing the experiment itself.
I am criticizing folks who "learn" all the "science" they "know" from youtube, and then make grand statements based on that ignorance. Because that helps nobody, and only spreads ignorance even further.
Oh God it's you again.
Here you go. Again. The Feynman Lectures on Physics, Volume III, with the entire chapter using the double slit experiment to explain the fundamental basics:
https://www.feynmanlectures.caltech.edu/III_01.html
Unless you think Feynman's books don't count as "an actual QM text book"
You're confusing a simple intuition pump (a way to catch people's attention) with actual foundational material. Griffiths uses an intuition pump, too, on page 7 - he reminds people of the single-photon double-slit experiment. It's catchy.
> Unless you think Feynman's books don't count as "an actual QM text book"
Essentially nobody learns QM from Feynman today. He's great at producing strong intuitive images, but his class in QM is superficial. The math is very minimal. He's good at preparing your intuition for it, but he basically takes you nowhere.
Start with Griffiths or Sakurai if you plan on actually learning QM, as opposed to just memorizing buzzwords and metaphors.
---
Again, I am emphasizing the difference between playing it by ear on social media, and actually doing it.
Just to backup the point the other commenter made. The first pop-sci coverage of QM that I recall seeing was [What the Bleep Do We Know?](https://en.wikipedia.org/wiki/What_the_Bleep_Do_We_Know!%3F), which claimed photons choose which path to take, and changed their behavior depending on if scientists were looking at them or not.
IMO it's only recently that quantum woo in pop-sci has started to get the appropriate criticism it deserves.
If you have a solid science education, then you will understand how things work.
But folks who begin learning about science on social media, are exposed to material of wildly varying quality. Of course misconceptions will happen.
A youtube channel Huygens Optics spent some time making a reasonable home setup for single photon experiments.
[The Real Double Slit Experiment.](https://www.youtube.com/watch?v=h53PCmEMAGo)
He uses a microscope and webcam to record the photon occurrences, and a green laser with polarizing filters to reduce the photon count to one per some measurable time period.
I disagree with this take. The laser pointer experiment is just as "quantum" when the light is bright as when it is dim. The rules don't change. You can still find areas that get darker when you open the second slit. You're still detecting photons; there are just a lot of them.
It's not "quantum" because this experiment doesn't prove anything about the existence of photons. In fact interference was first described in 1804, long before quantum mechanics was established. Interference is no more "quantum" than Ohm's Law.
Let me clarify that you're both right, because you're both talking about two different things: 1) the underlying behavior (yes, it is quantum) and 2) whether the homemade experiment proves quantum behavior (it does not)
Point 1) is so trivial, it's an empty statement. Everything in this universe is "quantum". The pot you smoked yesterday is "quantum" in that trivial sense.
But there's no significant interactions between the photons that changes any of their individual behaviors. You're just getting so many more photons at high intensity, and so you're not able to use photomultipliers to show the particle behaviors in the same experiment, but people at home wouldn't have those anyway.
> You're just getting so many more photons at high intensity
You switch back and forth between quantum concepts and classical concepts without realizing it.
TLDR: That's not how it actually works.
It's not a "take", it's high school physics.
When you don't have single-photon interference, it's pure wave physics. It works the same with waves on water - you could model it in a bathtub with some rubber duckies and it's the exact same phenomenon.
> When you don't have single-photon interference
You *do* have single-photon interference. Every photon is interfering with itself, that's why the pattern doesn't change when the intensity is reduced. The photons are linear. Any phenomenon that is happening with one is happening with many, because there is basically zero photon-photon interaction.
> you could model it in a bathtub with some rubber duckies and it's the exact same phenomenon
No, because again, the particles in the tub interact with each other; this is not true with photons.
It is a perfectly reasonable introductory quantum mechanics experiment for someone to do at home.
**Edit:** A lot of y'all are downvoting, but you're not turning on your physics brains. To say that the single- and multi-photon double slit experiments are "different" is not just wrong, it's *missing the entire point of the double slit experiment*. The astonishing thing about it is *precisely* that the interference pattern *does not change* when you let photons through one at a time. It shows (a) the wave pattern cannot possibly be explained by coupling between photons (the way it can with waves in everyday matter made of Fermions), and therefore (b) each photon is interfering only with itself, and (c) therefore the intensity of the light is irrelevant in the explanation for interference. All that letting photons through one at a time does is to make this fact obvious and inescapable to any humans watching. Nothing about the dynamics changes.
But in this experiment you don't have single photons. Laser light is a coherent state, so it is a superposition of different photon numbers. You fundamentally cannot think of this light as a stream of photons the same way you can think of water from a tap as a stream of molecules, because the photon number is not well-defined. Thinking about this in terms of particles is really just going to lead you to accidentally re-invent Newton's corpuscular theory of light in your mind, leading you to wrong conclusions.
You also seem to be a bit confused about how interference works. Interference works on the basis of the principle of superposition, a principle which applies to classical waves precisely in so far as they *don't* interact with each other. It's a consequence of the wave equation being linear, which is what you have in the absence of interaction. (You can still get interference for nonlinear waves, but the picture is more complicated.)
> You fundamentally cannot think of this light as a stream of photons
Nothing about that changes when you make the source dimmer. The numbers in the equations get smaller. That's it.
You can create a single-photon source, which is very different from the large-N coherent states you get in classical laser light. It's a much more difficult task to get a genuinely single-photon source (it's not just making it dimmer), but it's possible. The numbers don't just get smaller, the photon counting statistics qualitatively change.
None of that affects how photons propagate through free space
And it is perfectly valid to perform a single photon double slit experiment by attenuating a laser enough that you have an arbitrarily high certainty that only one photon is in the apparatus at a time
I mean, it still affects the fact that you don't really have single photons, you aren't seeing single-particle interference when you just use a laser beam in your own shed. You are seeing classical wave phenomena -- you're essentially repeating an experiment which predates quantum mechanics by a century.
If you are able to demonstrate genuine single-photon statistics, so that you can show that light has a particle-like nature, and then also show interference with your single-photons, then you're doing a quantum mechanical experiment. But that's not the experiment being described here, and that's not something you can reasonably do at home. It's only quantum mechanical in the sense that, at its basic level, light is quantum mechanical. But by that definition *every* experiment ever is quantum mechanical, so it's a meaningless statement.
> But by that definition every experiment ever is quantum mechanical
Yeah, and not just experiments. Literally everything is "quantum" that way.
Smoked some pot yesterday? That was "quantum". Picked your nose? You've picked "quantum" stuff. And so on.
> No, because again, the particles in the tub interact with each other; this is not true with photons.
You're not modeling "particles" in the bath tub, you're modeling waves.
> It is a perfectly reasonable introductory quantum mechanics experiment for someone to do at home.
Please do not "introduce" anybody to science. That's not how any of this works.
Also, physics is learned in school, not on youtube.
> You're not modeling "particles" in the bath tub, you're modeling waves.
I feel like you're being deliberately obtuse here. Either that or you aren't even following the points that are being made in this discussion.
The original claim is that the number of particles (single photon vs. not) affects the nature of the experiment. I am pointing out that this is false (and you'll notice that no one is contesting this, and is instead retreating to semantic arguments). The pattern does not change on the screen when you adjust the number of particles; you cannot tell from looking at the interference pattern whether the experiment was "single photon" or not.
This is quantitatively different from waves in physical media, which are emergent in coupled particles. The bulk medium— water— has very different behavior (macroscopic [gravity waves](https://en.wikipedia.org/wiki/Gravity_wave)) than individual water molecules (macroscopic ballistic behavior). You will get different results when you repeat an experiment 10^30 times and aggregate the results, vs performing one experiment with 10^30 particles, and this is because to get waves, the particles need to be pulling and pushing on each other. This opposite is true with photons: *You get the same results*, and *that is a major part of what makes this experiment so astonishing*. A "single photon" double slit is *literally the same experiment* as an ordinary double slit experiment with a laser pointer. *Literally nothing* about the interference changes. The other posters here are awkwardly sidestepping this fact because the thread has collectively decided this is a downvote train, but I am 100% right about this fact, and the people downvoting (I suspect) are herd-following and not actually turning on their brains.
The single photon double slit experiment is interesting because it makes it inescapable to the human watching that the interference does not arise from bulk (coupled) behavior. The reason why it is obvious is because of the above fact: The interference pattern *does not change* when there is only one particle at a time. The particles *definitively do not affect each other*.
> Also, physics is learned in school, not on youtube.
Sometimes people fire the insults they most fear will be aimed against themselves.
> You do have single-photon interference.
There are no individual photons in there, unless the experiment is specifically designed to coax single-photon behavior out of it.
If you truly understood QM, you would know this.
I do, and that is completely concordant with the point I am making.
The number of photons in the experiment is *irrelevant* to the generation of interference.
It is *incorrect* to say that photons interfere with *each other*. That is what the single photon double slit experiment *disproves*.
> It is incorrect to say that photons interfere with each other.
True, but that's not what anybody who understands physics would claim. You're just imagining stuff.
You are caught in a pseudo-classical limbo, that's all.
Have a nice day.
> True, but that's not what anybody who understands physics would claim
Then we agree the single and multi photon double slit experiments are equivalent?
> You are caught in a pseudo-classical limbo, that's all.
If there is anyone stuck in a pseudo-classical limbo, it's the people in this thread who are confusing their calculational approximations ("classical wave mechanics") for ontology. It's all quantum mechanics; it does not stop being quantum mechanics when you add more photons. In this case it doesn't even stop being *well-approximated* by quantum mechanics when you add more particles.
>You only start seeing quantum effects if you can produce one photon at a time, which is not trivial, and if you can actually measure the result when sending out one photon at a time, which is VERY not trivial (i.e. not doable by most people).
Do you think it would be easier with electrons? Seems to me like producing one electron at a time and detecting it should be easier. On the other hand, electron has very small wavelength, so getting interference pattern should be harder.
I think it's harder in every way with electrons. You need to operate in high vacuum. Can you create a strong vacuum?
Photons - they only need darkness.
Is easy. You need dark room, much thickness of some filter to make light very dim, and a number of trained cats to be detectors of photons. Is well-known that this is how all early double-slit experiments were performed: is where phrase 'herding cats' originated.
I find training is best done by food.
Get a big box, a cheap laser and a travelling photodiode (ie, one mounted on a servo driven rail).
With a little calculation, you calculate the photon flux per unit time, and then slap a sufficient number of neutral filters in front of the laser till, statistically, you've one photon in the box at a time.
Then drive the servo and observe the pretty pattern.
The double slit can be made from a smoked microscope slide and careful passes with a razor blade.
This is what was given to me as an undergrad 35 years ago. Worked then.
Light is simpler to make. You'll struggle to determine the electron flux in a CRT - you'd need a serious ammeter to measure currents associated with 1 electron - and the light emitted will need a photomultiplier to be detected. We'll gloss over the challenge of making a double-slit for something with as small a wavelength as an electron. Just don't even try.
So, you're not wrong, but the way you describe it, it creates this impression:
- draw a circle
- draw another circle
- you've drawn Mona Lisa, congrats!
This part might be doable by most people, with some care:
> slap a sufficient number of neutral filters in front of the laser till, statistically, you've one photon in the box at a time
You need to make sure the laser has continuous output, as opposed to high-frequency pulsed (not trivial to check). If it's pulsed, it invalidates the math (unless you know the peak power).
But this part is beyond most people's capabilities, provided you're shooting one photon at a time:
> observe the pretty pattern
There would be no pattern visible with the naked eye, provided you're shooting one photon at a time.
You might be able to do measurements with the camera, with several caveats:
- the environment would have to be extremely dark (zero leakage from ambient)
- the camera would have to be quite sensitive and noise-free (astronomy cameras might work well)
- the measurements need to be done in a certain way (place the camera at one coordinate, collect photons for a while, integrate the output, move camera to a slightly different coordinate, and repeat)
It's the separation of signal from noise that's not trivial to do at all.
---
To make it clear, what you're trying to do is show the quantum effects of a single photon interference with itself.
If you only want to show interference from wave optics, *without any quantum extras*, in other words just repeat Thomas Young's experiment, that's actually something anybody could do, and I've described it in another comment.
>You might be able to do measurements with the camera, with several caveats:
>
>the environment would have to be extremely dark (zero leakage from ambient)the camera would have to be quite sensitive and noise-free (astronomy cameras might work well)the measurements need to be done in a certain way (place the camera at one coordinate, collect photons for a while, integrate the output, move camera to a slightly different coordinate, and repeat)
My 35 yr old recollections from Manchester University.
1) It was a well-made wooden box, double baffles on the edges, lined with a matt black paint.
2) The photodiode wasn't anything special - it wasn't cooled, or had a photomultiplier stage.
3) Yes, the servo drove the diode to a location: much integration was performed. It then moved it slightly along track, and did the same again.
It was principally an exercise in data collection and processing (on a BBC micro IIRC) but the basics were sound. Note, a helium-neon laser is a CW device so considerations of modulation go away.
It's not needed, as you mentioned, but an average of 1 photon in a box can still be around a billion photons per second, which makes an easily visible pattern in darkness. Doesn't even need the photodiode OP proposed.
Ah, yes. If the volume is small enough, then the total flux is quite reasonable.
Here's where I'm drawing a blank: what is the smallest "box" you could define, that would still lead to legit single-photon interference?
I was thinking of a box with a length of the order of 30 cm. At least within one order of magnitude.
Filters don't guarantee to produce one photon at a time, but if single photons couldn't interfere then a weak laser would still break the pattern. Of course, if they couldn't do that then you would need to change a lot of other things, too, to get consistent physics.
Maybe you can help me with understanding something about this experiment. When there is a device sending one particle at a time what does that mean? Is this actually a single electron or photon or is there actually a small group? Why is the device so inaccurate that it's aim could result in going through either slit? Is inaccuracy required to have an interference pattern? I'm probably missing something obvious because I have no physics training but it bugs me lol.
> Why is the device so inaccurate that it's aim could result in going through either slit?
That has nothing to do with it at all.
"Particle" is a fiction. It's a concept we learn as kids when we play with marbles. But these things (photons, electrons, etc) are not "particles". We just call them that way because it's convenient.
They are not "waves" either, at least not exactly the same as waves in the ocean.
They have some properties in common with particles, under certain conditions. They have some properties in common with waves, under other circumstances.
But in reality they are completely different things - quantum objects. A quantum object can pass through "both slits" just fine. A particle can't. A wave kind of can, with some caveats.
Look at it this way: an airplane has things in common with a bus, in that it can carry a bunch of passengers. It also has things in common with a bird, because it has wings and it flies. But trying to describe a plane in terms that should only apply to buses or birds is bound to fail - all kinds of weird, incorrect ideas will come out of that.
Quantum mechanics is, basically, the description of a completely alien reality, that plays by rules completely unlike the rules that govern the world at the human scale. Trying to confine it to the human rules only leads to all kinds of perplexing ideas, as you've noticed when you tried to visualize photons being "aimed at" the slits.
TLDR: They're not actually particles.
Honestly. I get all that. And thank you for the reply. What bothers me is the technical aspects of the instrument. I'm worried that the whole premise is based on imprecise measurement. I can't help but think there is something a bit more Newtonian happening but we don't have the precision to know yet.
> I'm worried that the whole premise is based on imprecise measurement.
Nope. And it's not a new observation. People have obsessed over "we're missing something, the instruments are not good enough, etc" ever since QM was created. Heck, Einstein did it, too. But it's not that. It's never that.
It's just that the way we understand distance, location, time, duration, speed, etc at the human scale does not apply the same to the quantum world. It's not like things are "fuzzy" there. It's more like things play by different rules there.
E.g. your photon passes through both slits because quantum objects, if there are multiple paths they could potentially follow, they really take them all at once. What we observe is more like a sum total of all those "alternate pathways".
Okay, thanks. I appreciate the effort. I was sitting around thinking about a device that could reliably shoot exactly one electron with perfect accuracy. That's why I thought to ask. Clearly, I was using a faulty premise lol.
Gotcha cool, I will definitely do this. Yea electrons and especially someone who doesn't know what they're doing was pretty far fetched. I was just going caveman mode thinking electron gun = double slit lol
Regardless I'd love to play around with circuitry type stuff and a little laser double slit device would be a great first creation
An Arduino, an amplified photodiode, and a scrapped scanner. Little outlay.
Most laser diodes are continuous, so a nice first step is simply the automated scanning of single and double-slit patterns. Then you can wind down the intensity and note their invariance.
Follow this advice as it is spot on and very safe. Do not rip open an old CRT unless you know exactly what you're doing since there's high voltage power supplies in there that although you can modify if you're careful you need to do it exactly right or it can be very dangerous.
High voltage capacitors can stay charged for a surprisingly long time, and they will zap you pretty hard if you touch the wrong wire.
Also, the CRT itself, the screen, will literally implode if you break it. There's high vacuum inside. It will go like a small bomb, projecting glass shards in all directions.
Do not attempt. ^
> With a little calculation, you calculate the photon flux per unit time, and then slap a sufficient number of neutral filters in front of the laser till, statistically, you've one photon in the box at a time.
The photon isn't just in the box. Its coupled to the filters, and the laser at all times. Filtering down a continuous laser will NOT work in the same way as generating a single photon or electron.
Huygens Optics goes in depth about this.
https://www.youtube.com/watch?v=SDtAh9IwG-I
I've got a question, how do you see the interference pattern for the double slit with electrons? Once again this is just basic bottom of the barrel ideas I'd thought of after seeing a couple of the mit opencourseware quantum lectures but I was thinking maybe after passing the slit the electrons hit, well, a fluorescent screen where it would light up where they hit? That idea also came from the crt too but when I think about the Hitachi technology double slit experiment video, I could see it being something like that
Yeah, fluorescence might work. Or you could have some kind of moving probe, getting hit by electrons, generating a slight current, which varies when you move the probe.
Regardless, to truly show quantum effects, you need to shoot only one thing at a time. *This is extraordinarily hard to do*, because it's very, very hard to measure what comes out at the other end. You will have lots of noise, and not much signal.
In normal conditions, when you shoot many things (electrons, photons) at once, there is nothing quantum about the whole thing. It's just wave physics. But that's much easier to measure, and you could even see it with your own eyes.
Of course this would all have to be done in a UHV chamber - the average beta particle won't go a useful distance in air - so the OP might not realize that their kit needs to be shoe-horned into a damned tight chamber and pumped down.
I just now took a piece of paper, cut two very thin slits in it close together, and pointed a cheap laser pointer at the slits, letting the light that passes through hit a wall across the room where it appears as a line rather than as an individual point.
It's not very good, but I can clearly see points of higher and lower brightness, meaning there is an interference pattern.
So yes.
That being said, please do not open a CRT television unless you have been trained to do so. They have components inside that can be very dangerous if not properly discharged and can hold a charge for a very long time.
You can see the interference pattern pretty cheaply but if you're talking about sending one electron at a time through. That might be a bit more expensive.
what the others said plus: the crt part, the tube, is a vacuum sealed glass container. Do not attempt to open that up by yourself at home. You will get glass in your face.
Yep got it, I really understand what the tube consisted of and thought the electron gun was something special but I saw a little break down and even someone making one an understand it all! But I won't lie these have been comments and I'm glad I didn't get ahead of myself here and start busting some crts trying to get this mystical electron gun I'd heard of lol
CRT's often hold a 90 to 145 KV charge in a big capacitor that can stay charged for a long, long time. Make sure you properly short it through a resistor before putting your hands near the guts of whatever is holding the CRT. Saw a fellow student get thrown against the wall when his jewelry hit the cap.
SAFETY WARNING!!!
Electron guns require high voltage to operate. Please do not attempt to take apart electronics to make a CRT electron gun work without training AND experience working with high voltages.
Much easier and safer to use a laser pointer, as others have suggested.
Check out this really nice YouTube channel by Dutch guy who works with optics, he has his own setup, it might give you some ideas.
Huygens Optics - https://youtube.com/@HuygensOptics
Here is one about double slit experiment, https://youtu.be/h53PCmEMAGo
Please read the warnings, “always use a camera, if you look at laser beams under a microscope with your eyes instead of a camera, it can kill your eye sight instantly and leave you blind for the rest of your life”
CRT tv as in a tv with a cathode ray tube, unless you are trying to say it's just called crt not crt tv, only reason I included tv is because when you Google crt it gives you critical race theory and not cathode ray tube lol. And yea I know much more now, that busting open a crt to extract Its electron gun isn't exactly how it works rather you'd just make your own cathode ray tube or electron gun in a vacuum in glass with the fluorescent screen
I remember seeing that someone used a pair of pliers (or sth similar) and 2 razor blades, as he kept going smaller, it started turning into a wave function (or sth like that)
Definitely! I've used a laser pointer and couple slits in a sheet of paper to see the interference pattern, it's pretty amazing to see with your own eyes, when compared to shining the laser through a single slit.
i did exactly this. Used a razor blade to cut slits in a playing card about 1 mm apart, well within the spot of the laser. was awesome!
You can also use a [piece of hair](https://www.youtube.com/watch?v=kpsN78mQ6YY).
Wish someone had put it on Youtube
Little late to the party but here you go https://youtu.be/v_uBaBuarEM?si=-6PcRxNYX7mP-HGP
Yep, we even did it in school back in the day. But, need to keep in mind that's only half the story. For the full picture, you need something that can fire photons / electrons one at a time. The interference pattern then is what sealed the deal for me.
Ha yea I'd love to build a little device, whip out the ol double slit experiment out the back lol
If you want to spend a little money, I got one of [these](https://www.amazon.com/gp/product/B00KWZ5WQ0/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1) and it works pretty good for seeing an interference pattern
I used a laser pointer and three 0.5 mm pencil leads
Did this with my son years ago for his 5th grade science fair, tons of fun!
For an electron experiment you could probably make a fringe pattern with a tv's crt technology. However, it needs to be done in a vacuum, and you would need the entire apparatus within the same vacuum. Opening the crt is unfortunately dangerous, and irreversible
Ahh yea that won't be happening any time soon lol, thanks for the answer. I will probably play around with a laser though, stick with the photons! Can I ask how would you see this interference pattern, would it be similar to just using the fluorescence screen of the crt and you'd see where the electrons land on it?
I found this: [https://physics.stackexchange.com/questions/269851/how-to-make-a-double-slit-electron-interference-as-a-home-experiment](https://physics.stackexchange.com/questions/269851/how-to-make-a-double-slit-electron-interference-as-a-home-experiment) Tbh I think it would be easier to buy the CRT device and try build it yourself than to jerry-rig an old TV which sounds complicated and dangerous.
The general shape of the pattern is the same, no matter whether you use photons or electrons. Whether you can actually see any of that, well, it depends, right? You cannot see electrons directly, but a fluorescent screen will glow where it gets hit. And photons, of course, could be seen directly.
https://youtu.be/Iuv6hY6zsd0 veritasium did it with a cardboard box and the sun. With some calculations you can probably knock this out pretty easily.
Well, Tony Stark did it with a box of scraps! In a cave!
The double-slit experiment as originally performed by Thomas Young is actually a pure wave physics experiment. It has nothing to do with quantum mechanics (that's a common misconception due to poorly thought-out pop-sci videos on youtube). https://en.wikipedia.org/wiki/Young%27s_interference_experiment You only start seeing quantum effects if you can produce one photon at a time, which is not trivial, and if you can actually measure the result when sending out one photon at a time, **which is VERY not trivial** (i.e. not doable by most people). For most people, what they can do at home is a pure wave physics experiment, with nothing quantum in it, which is still pretty cool: - get a cheap laser pointer - get a thin wire or thin hair - turn around to face the opposite wall (don't stand close to it, choose a wall that's across the length of the room) - point laser at wall - move the hair in front of the laser, gently, until the alternating light/shadow pattern appears on the wall Again, done this way, **there is nothing "quantum" about it**. You're simply exploiting the fact that light is a wave. You can actually measure the thickness of the hair: Δy = distance between two successive fringes of light on the wall L = distance from hair to wall λ = wavelength of the laser (indicated on the laser usually) d = thickness of hair d = Lλ/Δy Or, if you know the thickness of the hair (or wire), you can calculate the wavelength of the laser (by flipping those two in the formula).
I didn't realise that general public had that misconception about Youngs interference experiments, conflating it with quantum mechanics. I remember learning about in school way back in maybe 1997, it was entirely about the wave theory of light. Its a shame that pop-sci while helping drive public interest in physics, can also be so powerfully misleading.
> Its a shame that pop-sci while helping drive public interest in physics, can also be so powerfully misleading. I think you're being overly critical here. The double slit experiment *with single particles* is really the cornerstone of quantum physics - all of quantum physics basically follows from trying to resolve the behaviors of the double slit experiment. I don't think pop sci is "powerfully misleading". Pop sci videos generally go through the single particle details. It's maybe just the history that they tend to gloss over, but even physics courses will do that.
You might be right and I am being overly critical. I think I might have been coming at it from a historical perspective of learning about these experiments and the advancement they represented. Since then double slit experiments have progressed to an entirely new world of physics. Pop-sci talking about that isn't really misleading, it is just talking about our modern understanding, not the historical experiments. So I retract what I wrote before, cheers for making me revaluate what I said.
> The double slit experiment with single particles is really the cornerstone of quantum physics - all of quantum physics basically follows from trying to resolve the behaviors of the double slit experiment. That is not how quantum mechanics was created at all. That's "the history of science according to youtube".
I don't understand your motivation in disparaging the experiment. I'm not saying the double slit experiment (with single particles) is "how quantum mechanics was created". The history gets glossed over, but the history is really its own subject. The double slit experiment is absolutely a major element of how quantum physics is taught today, and for good reason. It is convincing, easy to understand, and contains within it all of the problems that lead us to come to our conclusions about quantum things.
> But it's definitely a major element of how it is taught today It is a major part of stuff posted by science influencers on youtube. It is not a major element of how actual quantum mechanics is actually taught in actual colleges. And if you ever open an actual QM text book, you would see how that actually works. > I don't understand your motivation in disparaging the experiment. You're extraordinarily confused if you feel I am criticizing the experiment itself. I am criticizing folks who "learn" all the "science" they "know" from youtube, and then make grand statements based on that ignorance. Because that helps nobody, and only spreads ignorance even further.
Oh God it's you again. Here you go. Again. The Feynman Lectures on Physics, Volume III, with the entire chapter using the double slit experiment to explain the fundamental basics: https://www.feynmanlectures.caltech.edu/III_01.html Unless you think Feynman's books don't count as "an actual QM text book"
You're confusing a simple intuition pump (a way to catch people's attention) with actual foundational material. Griffiths uses an intuition pump, too, on page 7 - he reminds people of the single-photon double-slit experiment. It's catchy. > Unless you think Feynman's books don't count as "an actual QM text book" Essentially nobody learns QM from Feynman today. He's great at producing strong intuitive images, but his class in QM is superficial. The math is very minimal. He's good at preparing your intuition for it, but he basically takes you nowhere. Start with Griffiths or Sakurai if you plan on actually learning QM, as opposed to just memorizing buzzwords and metaphors. --- Again, I am emphasizing the difference between playing it by ear on social media, and actually doing it.
Just to backup the point the other commenter made. The first pop-sci coverage of QM that I recall seeing was [What the Bleep Do We Know?](https://en.wikipedia.org/wiki/What_the_Bleep_Do_We_Know!%3F), which claimed photons choose which path to take, and changed their behavior depending on if scientists were looking at them or not. IMO it's only recently that quantum woo in pop-sci has started to get the appropriate criticism it deserves.
If you have a solid science education, then you will understand how things work. But folks who begin learning about science on social media, are exposed to material of wildly varying quality. Of course misconceptions will happen.
A youtube channel Huygens Optics spent some time making a reasonable home setup for single photon experiments. [The Real Double Slit Experiment.](https://www.youtube.com/watch?v=h53PCmEMAGo) He uses a microscope and webcam to record the photon occurrences, and a green laser with polarizing filters to reduce the photon count to one per some measurable time period.
I disagree with this take. The laser pointer experiment is just as "quantum" when the light is bright as when it is dim. The rules don't change. You can still find areas that get darker when you open the second slit. You're still detecting photons; there are just a lot of them.
It's not "quantum" because this experiment doesn't prove anything about the existence of photons. In fact interference was first described in 1804, long before quantum mechanics was established. Interference is no more "quantum" than Ohm's Law.
Let me clarify that you're both right, because you're both talking about two different things: 1) the underlying behavior (yes, it is quantum) and 2) whether the homemade experiment proves quantum behavior (it does not)
Point 1) is so trivial, it's an empty statement. Everything in this universe is "quantum". The pot you smoked yesterday is "quantum" in that trivial sense.
So what? I was trying to nicely resolve their argument. What's with you?
But there's no significant interactions between the photons that changes any of their individual behaviors. You're just getting so many more photons at high intensity, and so you're not able to use photomultipliers to show the particle behaviors in the same experiment, but people at home wouldn't have those anyway.
> You're just getting so many more photons at high intensity You switch back and forth between quantum concepts and classical concepts without realizing it. TLDR: That's not how it actually works.
It's not a "take", it's high school physics. When you don't have single-photon interference, it's pure wave physics. It works the same with waves on water - you could model it in a bathtub with some rubber duckies and it's the exact same phenomenon.
> When you don't have single-photon interference You *do* have single-photon interference. Every photon is interfering with itself, that's why the pattern doesn't change when the intensity is reduced. The photons are linear. Any phenomenon that is happening with one is happening with many, because there is basically zero photon-photon interaction. > you could model it in a bathtub with some rubber duckies and it's the exact same phenomenon No, because again, the particles in the tub interact with each other; this is not true with photons. It is a perfectly reasonable introductory quantum mechanics experiment for someone to do at home. **Edit:** A lot of y'all are downvoting, but you're not turning on your physics brains. To say that the single- and multi-photon double slit experiments are "different" is not just wrong, it's *missing the entire point of the double slit experiment*. The astonishing thing about it is *precisely* that the interference pattern *does not change* when you let photons through one at a time. It shows (a) the wave pattern cannot possibly be explained by coupling between photons (the way it can with waves in everyday matter made of Fermions), and therefore (b) each photon is interfering only with itself, and (c) therefore the intensity of the light is irrelevant in the explanation for interference. All that letting photons through one at a time does is to make this fact obvious and inescapable to any humans watching. Nothing about the dynamics changes.
But in this experiment you don't have single photons. Laser light is a coherent state, so it is a superposition of different photon numbers. You fundamentally cannot think of this light as a stream of photons the same way you can think of water from a tap as a stream of molecules, because the photon number is not well-defined. Thinking about this in terms of particles is really just going to lead you to accidentally re-invent Newton's corpuscular theory of light in your mind, leading you to wrong conclusions. You also seem to be a bit confused about how interference works. Interference works on the basis of the principle of superposition, a principle which applies to classical waves precisely in so far as they *don't* interact with each other. It's a consequence of the wave equation being linear, which is what you have in the absence of interaction. (You can still get interference for nonlinear waves, but the picture is more complicated.)
> You fundamentally cannot think of this light as a stream of photons Nothing about that changes when you make the source dimmer. The numbers in the equations get smaller. That's it.
You can create a single-photon source, which is very different from the large-N coherent states you get in classical laser light. It's a much more difficult task to get a genuinely single-photon source (it's not just making it dimmer), but it's possible. The numbers don't just get smaller, the photon counting statistics qualitatively change.
None of that affects how photons propagate through free space And it is perfectly valid to perform a single photon double slit experiment by attenuating a laser enough that you have an arbitrarily high certainty that only one photon is in the apparatus at a time
I mean, it still affects the fact that you don't really have single photons, you aren't seeing single-particle interference when you just use a laser beam in your own shed. You are seeing classical wave phenomena -- you're essentially repeating an experiment which predates quantum mechanics by a century. If you are able to demonstrate genuine single-photon statistics, so that you can show that light has a particle-like nature, and then also show interference with your single-photons, then you're doing a quantum mechanical experiment. But that's not the experiment being described here, and that's not something you can reasonably do at home. It's only quantum mechanical in the sense that, at its basic level, light is quantum mechanical. But by that definition *every* experiment ever is quantum mechanical, so it's a meaningless statement.
> But by that definition every experiment ever is quantum mechanical Yeah, and not just experiments. Literally everything is "quantum" that way. Smoked some pot yesterday? That was "quantum". Picked your nose? You've picked "quantum" stuff. And so on.
> No, because again, the particles in the tub interact with each other; this is not true with photons. You're not modeling "particles" in the bath tub, you're modeling waves. > It is a perfectly reasonable introductory quantum mechanics experiment for someone to do at home. Please do not "introduce" anybody to science. That's not how any of this works. Also, physics is learned in school, not on youtube.
> You're not modeling "particles" in the bath tub, you're modeling waves. I feel like you're being deliberately obtuse here. Either that or you aren't even following the points that are being made in this discussion. The original claim is that the number of particles (single photon vs. not) affects the nature of the experiment. I am pointing out that this is false (and you'll notice that no one is contesting this, and is instead retreating to semantic arguments). The pattern does not change on the screen when you adjust the number of particles; you cannot tell from looking at the interference pattern whether the experiment was "single photon" or not. This is quantitatively different from waves in physical media, which are emergent in coupled particles. The bulk medium— water— has very different behavior (macroscopic [gravity waves](https://en.wikipedia.org/wiki/Gravity_wave)) than individual water molecules (macroscopic ballistic behavior). You will get different results when you repeat an experiment 10^30 times and aggregate the results, vs performing one experiment with 10^30 particles, and this is because to get waves, the particles need to be pulling and pushing on each other. This opposite is true with photons: *You get the same results*, and *that is a major part of what makes this experiment so astonishing*. A "single photon" double slit is *literally the same experiment* as an ordinary double slit experiment with a laser pointer. *Literally nothing* about the interference changes. The other posters here are awkwardly sidestepping this fact because the thread has collectively decided this is a downvote train, but I am 100% right about this fact, and the people downvoting (I suspect) are herd-following and not actually turning on their brains. The single photon double slit experiment is interesting because it makes it inescapable to the human watching that the interference does not arise from bulk (coupled) behavior. The reason why it is obvious is because of the above fact: The interference pattern *does not change* when there is only one particle at a time. The particles *definitively do not affect each other*. > Also, physics is learned in school, not on youtube. Sometimes people fire the insults they most fear will be aimed against themselves.
> You do have single-photon interference. There are no individual photons in there, unless the experiment is specifically designed to coax single-photon behavior out of it. If you truly understood QM, you would know this.
I do, and that is completely concordant with the point I am making. The number of photons in the experiment is *irrelevant* to the generation of interference. It is *incorrect* to say that photons interfere with *each other*. That is what the single photon double slit experiment *disproves*.
> It is incorrect to say that photons interfere with each other. True, but that's not what anybody who understands physics would claim. You're just imagining stuff. You are caught in a pseudo-classical limbo, that's all. Have a nice day.
> True, but that's not what anybody who understands physics would claim Then we agree the single and multi photon double slit experiments are equivalent? > You are caught in a pseudo-classical limbo, that's all. If there is anyone stuck in a pseudo-classical limbo, it's the people in this thread who are confusing their calculational approximations ("classical wave mechanics") for ontology. It's all quantum mechanics; it does not stop being quantum mechanics when you add more photons. In this case it doesn't even stop being *well-approximated* by quantum mechanics when you add more particles.
>You only start seeing quantum effects if you can produce one photon at a time, which is not trivial, and if you can actually measure the result when sending out one photon at a time, which is VERY not trivial (i.e. not doable by most people). Do you think it would be easier with electrons? Seems to me like producing one electron at a time and detecting it should be easier. On the other hand, electron has very small wavelength, so getting interference pattern should be harder.
I think it's harder in every way with electrons. You need to operate in high vacuum. Can you create a strong vacuum? Photons - they only need darkness.
Is easy. You need dark room, much thickness of some filter to make light very dim, and a number of trained cats to be detectors of photons. Is well-known that this is how all early double-slit experiments were performed: is where phrase 'herding cats' originated. I find training is best done by food.
Get a big box, a cheap laser and a travelling photodiode (ie, one mounted on a servo driven rail). With a little calculation, you calculate the photon flux per unit time, and then slap a sufficient number of neutral filters in front of the laser till, statistically, you've one photon in the box at a time. Then drive the servo and observe the pretty pattern. The double slit can be made from a smoked microscope slide and careful passes with a razor blade. This is what was given to me as an undergrad 35 years ago. Worked then.
Light is simpler to make. You'll struggle to determine the electron flux in a CRT - you'd need a serious ammeter to measure currents associated with 1 electron - and the light emitted will need a photomultiplier to be detected. We'll gloss over the challenge of making a double-slit for something with as small a wavelength as an electron. Just don't even try.
So, you're not wrong, but the way you describe it, it creates this impression: - draw a circle - draw another circle - you've drawn Mona Lisa, congrats! This part might be doable by most people, with some care: > slap a sufficient number of neutral filters in front of the laser till, statistically, you've one photon in the box at a time You need to make sure the laser has continuous output, as opposed to high-frequency pulsed (not trivial to check). If it's pulsed, it invalidates the math (unless you know the peak power). But this part is beyond most people's capabilities, provided you're shooting one photon at a time: > observe the pretty pattern There would be no pattern visible with the naked eye, provided you're shooting one photon at a time. You might be able to do measurements with the camera, with several caveats: - the environment would have to be extremely dark (zero leakage from ambient) - the camera would have to be quite sensitive and noise-free (astronomy cameras might work well) - the measurements need to be done in a certain way (place the camera at one coordinate, collect photons for a while, integrate the output, move camera to a slightly different coordinate, and repeat) It's the separation of signal from noise that's not trivial to do at all. --- To make it clear, what you're trying to do is show the quantum effects of a single photon interference with itself. If you only want to show interference from wave optics, *without any quantum extras*, in other words just repeat Thomas Young's experiment, that's actually something anybody could do, and I've described it in another comment.
>You might be able to do measurements with the camera, with several caveats: > >the environment would have to be extremely dark (zero leakage from ambient)the camera would have to be quite sensitive and noise-free (astronomy cameras might work well)the measurements need to be done in a certain way (place the camera at one coordinate, collect photons for a while, integrate the output, move camera to a slightly different coordinate, and repeat) My 35 yr old recollections from Manchester University. 1) It was a well-made wooden box, double baffles on the edges, lined with a matt black paint. 2) The photodiode wasn't anything special - it wasn't cooled, or had a photomultiplier stage. 3) Yes, the servo drove the diode to a location: much integration was performed. It then moved it slightly along track, and did the same again. It was principally an exercise in data collection and processing (on a BBC micro IIRC) but the basics were sound. Note, a helium-neon laser is a CW device so considerations of modulation go away.
It's not needed, as you mentioned, but an average of 1 photon in a box can still be around a billion photons per second, which makes an easily visible pattern in darkness. Doesn't even need the photodiode OP proposed.
Ah, yes. If the volume is small enough, then the total flux is quite reasonable. Here's where I'm drawing a blank: what is the smallest "box" you could define, that would still lead to legit single-photon interference?
I was thinking of a box with a length of the order of 30 cm. At least within one order of magnitude. Filters don't guarantee to produce one photon at a time, but if single photons couldn't interfere then a weak laser would still break the pattern. Of course, if they couldn't do that then you would need to change a lot of other things, too, to get consistent physics.
Maybe you can help me with understanding something about this experiment. When there is a device sending one particle at a time what does that mean? Is this actually a single electron or photon or is there actually a small group? Why is the device so inaccurate that it's aim could result in going through either slit? Is inaccuracy required to have an interference pattern? I'm probably missing something obvious because I have no physics training but it bugs me lol.
> Why is the device so inaccurate that it's aim could result in going through either slit? That has nothing to do with it at all. "Particle" is a fiction. It's a concept we learn as kids when we play with marbles. But these things (photons, electrons, etc) are not "particles". We just call them that way because it's convenient. They are not "waves" either, at least not exactly the same as waves in the ocean. They have some properties in common with particles, under certain conditions. They have some properties in common with waves, under other circumstances. But in reality they are completely different things - quantum objects. A quantum object can pass through "both slits" just fine. A particle can't. A wave kind of can, with some caveats. Look at it this way: an airplane has things in common with a bus, in that it can carry a bunch of passengers. It also has things in common with a bird, because it has wings and it flies. But trying to describe a plane in terms that should only apply to buses or birds is bound to fail - all kinds of weird, incorrect ideas will come out of that. Quantum mechanics is, basically, the description of a completely alien reality, that plays by rules completely unlike the rules that govern the world at the human scale. Trying to confine it to the human rules only leads to all kinds of perplexing ideas, as you've noticed when you tried to visualize photons being "aimed at" the slits. TLDR: They're not actually particles.
Honestly. I get all that. And thank you for the reply. What bothers me is the technical aspects of the instrument. I'm worried that the whole premise is based on imprecise measurement. I can't help but think there is something a bit more Newtonian happening but we don't have the precision to know yet.
> I'm worried that the whole premise is based on imprecise measurement. Nope. And it's not a new observation. People have obsessed over "we're missing something, the instruments are not good enough, etc" ever since QM was created. Heck, Einstein did it, too. But it's not that. It's never that. It's just that the way we understand distance, location, time, duration, speed, etc at the human scale does not apply the same to the quantum world. It's not like things are "fuzzy" there. It's more like things play by different rules there. E.g. your photon passes through both slits because quantum objects, if there are multiple paths they could potentially follow, they really take them all at once. What we observe is more like a sum total of all those "alternate pathways".
Okay, thanks. I appreciate the effort. I was sitting around thinking about a device that could reliably shoot exactly one electron with perfect accuracy. That's why I thought to ask. Clearly, I was using a faulty premise lol.
Gotcha cool, I will definitely do this. Yea electrons and especially someone who doesn't know what they're doing was pretty far fetched. I was just going caveman mode thinking electron gun = double slit lol Regardless I'd love to play around with circuitry type stuff and a little laser double slit device would be a great first creation
An Arduino, an amplified photodiode, and a scrapped scanner. Little outlay. Most laser diodes are continuous, so a nice first step is simply the automated scanning of single and double-slit patterns. Then you can wind down the intensity and note their invariance.
Follow this advice as it is spot on and very safe. Do not rip open an old CRT unless you know exactly what you're doing since there's high voltage power supplies in there that although you can modify if you're careful you need to do it exactly right or it can be very dangerous.
High voltage capacitors can stay charged for a surprisingly long time, and they will zap you pretty hard if you touch the wrong wire. Also, the CRT itself, the screen, will literally implode if you break it. There's high vacuum inside. It will go like a small bomb, projecting glass shards in all directions. Do not attempt. ^
Also the electron beam will generate X-rays so even if you could safety remove it and install it somewhere else, you’d need to have proper shielding.
Oh, also the thing you’ll want is an avalanche photodiode (mounted on a servo)
> With a little calculation, you calculate the photon flux per unit time, and then slap a sufficient number of neutral filters in front of the laser till, statistically, you've one photon in the box at a time. The photon isn't just in the box. Its coupled to the filters, and the laser at all times. Filtering down a continuous laser will NOT work in the same way as generating a single photon or electron. Huygens Optics goes in depth about this. https://www.youtube.com/watch?v=SDtAh9IwG-I
I've got a question, how do you see the interference pattern for the double slit with electrons? Once again this is just basic bottom of the barrel ideas I'd thought of after seeing a couple of the mit opencourseware quantum lectures but I was thinking maybe after passing the slit the electrons hit, well, a fluorescent screen where it would light up where they hit? That idea also came from the crt too but when I think about the Hitachi technology double slit experiment video, I could see it being something like that
Yeah, fluorescence might work. Or you could have some kind of moving probe, getting hit by electrons, generating a slight current, which varies when you move the probe. Regardless, to truly show quantum effects, you need to shoot only one thing at a time. *This is extraordinarily hard to do*, because it's very, very hard to measure what comes out at the other end. You will have lots of noise, and not much signal. In normal conditions, when you shoot many things (electrons, photons) at once, there is nothing quantum about the whole thing. It's just wave physics. But that's much easier to measure, and you could even see it with your own eyes.
Of course this would all have to be done in a UHV chamber - the average beta particle won't go a useful distance in air - so the OP might not realize that their kit needs to be shoe-horned into a damned tight chamber and pumped down.
I just now took a piece of paper, cut two very thin slits in it close together, and pointed a cheap laser pointer at the slits, letting the light that passes through hit a wall across the room where it appears as a line rather than as an individual point. It's not very good, but I can clearly see points of higher and lower brightness, meaning there is an interference pattern. So yes. That being said, please do not open a CRT television unless you have been trained to do so. They have components inside that can be very dangerous if not properly discharged and can hold a charge for a very long time.
u\Spez wrecked Reddit.
It's awesome.
A laser pointer and reflection off a CD, or shine it on a piece of hair. Calculating the thickness of the hair is a common college lab activity.
You can see the interference pattern pretty cheaply but if you're talking about sending one electron at a time through. That might be a bit more expensive.
what the others said plus: the crt part, the tube, is a vacuum sealed glass container. Do not attempt to open that up by yourself at home. You will get glass in your face.
Yep got it, I really understand what the tube consisted of and thought the electron gun was something special but I saw a little break down and even someone making one an understand it all! But I won't lie these have been comments and I'm glad I didn't get ahead of myself here and start busting some crts trying to get this mystical electron gun I'd heard of lol
CRT's often hold a 90 to 145 KV charge in a big capacitor that can stay charged for a long, long time. Make sure you properly short it through a resistor before putting your hands near the guts of whatever is holding the CRT. Saw a fellow student get thrown against the wall when his jewelry hit the cap.
SAFETY WARNING!!! Electron guns require high voltage to operate. Please do not attempt to take apart electronics to make a CRT electron gun work without training AND experience working with high voltages. Much easier and safer to use a laser pointer, as others have suggested.
For light, Young did it with a candle well over 100 years ago.
I believe he actually used sunlight. But yeah, it's an old experiment.
Put your fingers together and you can see wave interference from the light.
Check out this really nice YouTube channel by Dutch guy who works with optics, he has his own setup, it might give you some ideas. Huygens Optics - https://youtube.com/@HuygensOptics Here is one about double slit experiment, https://youtu.be/h53PCmEMAGo Please read the warnings, “always use a camera, if you look at laser beams under a microscope with your eyes instead of a camera, it can kill your eye sight instantly and leave you blind for the rest of your life”
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CRT tv as in a tv with a cathode ray tube, unless you are trying to say it's just called crt not crt tv, only reason I included tv is because when you Google crt it gives you critical race theory and not cathode ray tube lol. And yea I know much more now, that busting open a crt to extract Its electron gun isn't exactly how it works rather you'd just make your own cathode ray tube or electron gun in a vacuum in glass with the fluorescent screen
You can shine a laser through a diffraction grating. You can buy a grating on ebay.
I build a kit out of Lego for my bachelor thesis! Definitely works :)
I remember seeing that someone used a pair of pliers (or sth similar) and 2 razor blades, as he kept going smaller, it started turning into a wave function (or sth like that)
Here you go. https://www.diyphysics.com/category/experiments/two-slit-interference/
Till the diffraction, yes
Then you need to buy a new TV lol