Agreed; the cat metaphors are extremely distracting. Can you please take this a little more seriously next time, minutephysics? It's more important for the lesson to be clear than "funny" or meme-like.

agreed. Cat ruins my intuition.

@Ostbuggen thank u

Is it that hard to replace "cat" with "particle" in your head? It's not like there's any depth to the metaphor. It's not like any parts or aspects of a cat gets further compared to quantum particles. In fact, it's so meaningless that i wouldn't even call it a metaphor. It's just a goof.

Ostbuggen . That point was *meow*

That's exactly what I told my Mother

I agree.

Yea, its really confusing

The cats were the only part I understood.

yeah, i get the part about lightwaves, don't understand the cats lol.

but cat is easier to pronounce than electrons

Agree

The point was that the experiment works with macroscopic objects as well as with particles

@@KenCubed I think what you mean to say is that the experiment has been done with particles (such as bucky balls) and not just light.

@Stephen PCMR Yes, it does. You could send whales through double slits and still get the same interference pattern.

Yes

They are light particles

@@minecraftmadison462 not only

no. waves. yes. particles. it's complicated :P joke aside he's using cats as standin for "any quantum-behaving thing" because of the fameous schroedinger's cat.

Wikipedia says on Double-slit experiment: "The experiment can be done with entities much larger than electrons and photons, although it becomes more difficult as size increases. The largest entities for which the double-slit experiment has been performed were molecules that each comprised 810 atoms (whose total mass was over 10,000 atomic mass units)."

Craig Blanton “ I don’t even know what I don’t know about this “ ever since I said it my cat has been looking the smuggest. I knew cats perfectly understood quantum paradoxes and we’re just not explaining. It’s so they can lord it over us, I bet.

Did they launch them at the slits using cat-apults?

No, because nobody likes cats.

Those are Shrodinger's cats, there are simultaneously innocent and not and the same time.

@@Mernom you know, I was going to make a dumb catspiracy joke, but now I feel dumb for making a dumber joke...

Time to test schrodinger's cat.

Schrödinger was obsessed too it must be a physicist thing.

toxoplasmosis

even bartonella

CALL PETA

He probably wanted to avoid a paradogs. 😄

@@Bodyknock *GET OUT*

@@Bodyknock Read my mind Doug, that's a dangerous place to be.

He didnt want to be that dogmatic 😏

No. Is like saying a proton is the anti electron.

In cat darkness where only chaos reigns one man finds a way to bring back light by having the cat and anti cat go through the same slit both blocking the other one but both reaching this world by the power of quantum mechanics.

My guess is that if they do, they have to interact, which collapses their wavefunction.

It was implied by his cat analogy that the concept is fairly general and can apply to different types of particles. In the case of photons, they could be made to be phase-shifted from each other in such a way that they cancel each other out completely at the middle slit. These two photons could be viewed as being the "anti" counterparts to each other.

@@Mernom I thought that too. But if that happens, then after they have interact and their wavefunctions have collapsed, right after that, they'll continue to propagate in form of waves, so they will still make an interference pattern and so it should be accounted when adding all the states to the superposition, this forth state should be taken into account. If I'm not wrong. So I think what Flatgod said makes sense.

@@Flatgod yeah, that makes sense.

I assumed it was because the slit has only that much radius so either the particles cancel out or they bounce back, like in the gold foil experiment.

Satish Bhoos in truth nobody understands cats, even the famous cat psychologist Dr. Felix Grimalkin has admitted as such. So when we bring in quantum cats they are bound to behave only in statistically significant ways.

@Carl-Adam Berglund And cats.

Yeah exempt pilot wave theory requires you add extra math which means extra assumptions. That and you can't reconcile it with gravity at a quantum level, which is why De Broglie never went over to the pilot wave camp even though he was the first one to first suggest it.

@@odinakazeus You can't reconcile regular quantum mechanics with gravity either. But regular QM has a special-relativistic version (QFT), while Bohmian mechanics does not

I think the reason people don't try is because one can't. If it was pilot waves instead of superposition, both cats wouldn't go through. Nor can it explain or predict the double slit experiment, or the DCQE, or make a useful prediction for more than one particle at a time. That's why even Einstein didn't care for it; even though it fit better with his beliefs.

@@NJ-wb1cz No, she's Alice

@@NJ-wb1cz Cuz she picked "Looking Glass" as her nick

@@NJ-wb1cz Oh, I get that popularizers obsess over using Alice and Bob instead of A and B when they talk entanglement or some such - it's you who don't get Lewis Carroll, but that's OK

@@NJ-wb1cz You sound like a smartass (and what do you take me for, a peanut)? Obviously, that's why I said she's Alice

@@NJ-wb1cz Sure - or not, due to superposition

But this is not a paradox. Quantum mechanics is not fully understood so how can it be a paradox? A paradox is something you do understand in conflict with logic. Now with quantum mechanics it is something that is not fully understood in conflict with your logic. So theres a big separation.

@@vc2702 There are tonnes of things called paradoxes that aren't really paradoxes. People use the word "paradox" to describe basically anything counter-intuitive and unexpected nowadays.

@@zergreenone8111 Thanks for helping me understand.

The bottom cat is staying restricted to the bottom two slits as its own double-split experiment. Likewise for the top cat. The middle slit is shared as if the individual experiments were layered or superimposed on top of each other.

Feynstein 100 There is some possibility, yes, but the particle sources are arranged such that the probability is very, very low. By putting a mask between the bottom source and the slits that completely blocks the top slit, for example. Quantum being quantum, there’s still some non-zero chance the particle tunnels through the mask or diffracts at some crazy angle and goes through the top slit anyway, but the probability of that can be made small enough that its contribution to the final result is negligible.

@tehlaser Ahaha fair enough. Although, I guess there is a very simple way to test it: by running the experiment with only one cat and seeing if the third slit makes any difference to the results with two slits. :)

Feynstein 100 the feynman path integral does say a particle takes every possible path, but not equally. The path integral accounts for the likeliness of that happening by giving each possibility weight. The bottom two slits are equal length from the starting position, so equally likely, but the third top slit is a further distance so it is exponentially less likely because particles follow the shortest path. So the third slit does matter, but only like .000001%

Yeah, the cat goes out the front door, along the street, round the side of the end house, over the fences of the back gardens, then comes in through the back door. It's what cats do. Often repeatedly.

particle just means a tiny piece of matter, i dont think anyone literally thinks there are subatomic golf balls flying around the place

@@Blox117 thats just it they are not tiny pieces of matter they just behave like it under certain experiments, they are not any piece of particle thats just how the general populace (those who don't know anything of qm) like to think of sub atomic 'particles'.

Dunno what you're talking about. My cats display wave-like properties all the time.

The reason it’s talked about in that way is because it’s still weird and unintuitive. It’s not like we discovered quantum mechanics and now we all quantum tunnel through walls and scatter into probability waves when we walk through doors. Our experience of the physical world hasn’t changed so even though quantum mechanics describes the physical world extremely well, it’s still extremely confusing and novel to people new to the subject. Even experts on the subject talk about how difficult it is to visualize what’s actually happening in quantum mechanics and how if you think you understand it you probably don’t

Like a cucumber ??? cos I've been through this..

@@KariPurpleField 😂😂😂lol

Yes! Its the bane of my life when im watching YT after smoking a spliff and im on a munch. I try and choreograph my crunches to fall on music parts or transitions in the video to not miss as much.

So annoying when I tried to eat cereal with my morning TV

You win

Unfortunately with a lot of quantum mechanics there is no nice intuitive way to understand due to its very unintuitive nature. Niels Bohr said "If quantum mechanics hasn't profoundly shocked you, you haven't understood it yet." which I think pretty much sums it up

@@reddragon3132 there is always a simpler form but no simpler than it.

For me the expression as a superposition is rather simple. The superposition of all four slit pairs results in a pair of non-interacting double-slit experiments. Then you just subtract one of the cases, which alone would produce just a single peak with both types of cats mixed together. And, as we know, subtracting a non-zero value (wide peak) from a zero value (narrow troughs) results in a non-zero value (cats appearing in places where they wouldn't with either double slit experiment alone).

probably because you are seeing something that needs a lot of prior knowledge to fully understand. he tried to explain something expecting you to already know about how the experiment works. maybe if you go back and watch some of his videos or other videos about quantum entanglement it will be easier to understand.

Read “The Strange World of Quantum Mechanics” by Daniel Styer. I read it in my modern physics class and tbh it helps you understand quantum mechanics a lot easier. Although I feel like no one can TRULY understand quantum mechanics unless you major in physics + maybe get a graduate degree focused on quantum mechanics because of the subject’s huge contrasts with classical physics and general logic

That's a really good question, I actually have made a video to answer this : kzfaq.info/get/bejne/l9tghK2KrrnJZJc.html

Get used to it

Both

@@tomerwolberg37 or neither!

yes

The cat is in a superposition of position, momentum, alive or dead, hungry or fed, blue or red.

Which cat?? Shcrogringer?? Or ur neighbour's cat?

Yet in one result both cats are at the places where they could've only been if BOTH of them passed through the door at the same time

Such cats are clearly alive, and therefore not quantum-cats. They will then not create an interference pattern, but end up as spots on the wall.

Others might say, *Hard*l*y*

@@BrianCrink NP-complete hard

@@ObitoSigma Does it also include p hard😂

Its him i dont understand lol. A paradox is about something you do understand that is in direct conflect with logic. What he is talking about is NOT a paradox because it is something he does not fully understand in conflict with his logic. If you dont understand something its not a paradox. I dont understand women that does not make them a paradox it makes them something i dont understand in conflict with my logic.

I was fine with particles, but once he started using cats I was stupefied.lol

January called they want their meme back

I can't unsee it

@@jimohara4822 90s called and they want their insult back. I'm not ashamed I'm old though, you apparently think January is an outdated meme with a phrase decades old now. Old phrase is old.

Time dilation. There's quite a few videos on KZfaq about exactly this.

Well first of all there is no such thing as absolute motion, the theory is called relativity because you can only compare motion between two or more things, relativity actually did away with absolute rest and absolute motion and basically proves that there is no 'correct' coordinate system which you can move relative to (spacetime in your example) but there is due to other reasons the speed of light, c, which is invariant to all observers which causes time dilation and lengths to contract like you said. But you actually don't need absolute motion for what you are talking about, you can get that effect in this univerese. Say you pick two galaxies, in opposite directions from here and very far away. Due to the expansion of the universe, the left galaxy is travelling 0.6c away from us, and the right one is travelling the same, well from our point of view, it could be argued the left galaxy is travelling away from the right galaxy at 1.2 c or faster than the speed of light. For various other reasons like those listed above, including time dilation and the effects of acceleration you could never travel to those galaxies and measure that speed but from the earths inertial reference frame you could. And yes time would dilate and lengths would contract if you managed to reach one of the galaxies due to the speed you'd have to travel and so that would be the universes way of making sure everything always comes out to less than c.

The creation of the superposition when you fire a particle means that the particle always 'trys' to go through both slits!

@@brandonklein1 Right. I guess my point was if you could produce a situation where you could prevent either from going through the middle, by firing them off at once, then there would be no interference pattern. That there is a pattern means that, even if 'impossible', both particles must be able to still get through the middle slit, so they both do and don't. (don't mind me, just trying to wrap my head around this)

@@rhaythe They are both going through the middle, and both not going through the middle - but their superpositions are _linked._ If the individual states are A and B, the combined state is not (AA, AB, BA, BB) like you might expect. There's only three options, not four. That changes the probabilities. They are still going through the middle, but not as much.

@@DavidGuild Well, not quite: you still have four possibilities (as you must, due to linear algebra) - only thing is that one of the combos - say BB - is not detected by the apparatus. In other words, _the detected states are not 1-to-1 correlated with the initial states_

Even single slit has a corresponding interference pattern.. This is complicated

Sounds like u got issues

Log Nature I’m not denying that, lol

Because that isn't really relevant at all. Going into a bunch of detail about non-ideal slits and interactions with the material would just confuse people without helping them understand anything about quantum interference or superposition. What you're looking for sounds more like something you'd find in a college class on wave mechanics or something. To address some of your specific questions: - The wall thickness doesn't matter much, the pattern basically comes from the back side of the slits. - Reflection also doesn't do much, we don't care about the particles that bounce back, so it's mostly just reflections on the slit edges. The important thing is where the particles come from, so if the reflections still come from the slits the pattern will be the same. If they lose energy interacting with the wall then they could have a longer wavelength which would stretch out the pattern. - Changing the size of the slits can be interesting, you can get single slit interference where the light from one side of the slit interferes with light from the other side. - Particles passing through the wall should give you a background glow underneath the interference pattern, that would depend on the wall material but should be very small regardless.

Yeah, you're right. It's impossible to say that the slits does not interfere. Just remember that every particle carries around it a larger-then-the-slit field of something, it could be magnetic, it could be gravity, it could be the electrons cloud or even a unknown filed that interacts with the slit and with itself after going through the hole. Recent suggestions mention the Pilot Guide Wave as a field that "touches" the slit and creates interference.

Pathfinding?

@@WanderTheNomad well yeah its a particule trying to find a path through a set of 2 slits

@@WanderTheNomad for AI.

Found the nihilist!

because he is

Talent

I think he has a PhD, at least a graduate degree.

Because he is doing what he loves and explaining a topic he choose to and had time and knowledge to proper understand it and show in a very non-usual way... while your teacher has to do the same thing over and over for the whole year otherwise he won't be able to pay his bills.... Or we can simply keep up the idea that "youtube teachers" are always better than "real teachers" and keep putting the blame on other people

Thomas Urech pretty sure it’s a master’s

We did this in class with a laser pointer

He's covered that. And quantum venn diagrams... And i think the point of this is for people that totally get it and are bored with the classic double slit, and need to get their Freak On ;)

blackie blackless76541 thanks I understood you better than the video 😝

For sending one particle through three slits, you would likely get an interference pattern similar to the double slit experiment. As for the top going through the bottom and vice versa, there is likely a screen to block those possibilities to simplify the experiment.

Have you heard of the double slit experiment before? Maybe he's just assuming that some people already had prior knowledge when it comes to things like this. It was going at a good pace for me.

Play at half speed. Problem solved👍🏽😅

I think this video is expecting a lot of prior understanding on behalf of the viewer, which wouldn't be an issue if it had been stated at the beginning. I would bet that my flatmates studying quantum mechanics at uni would have found this useful for their studies, but for the rest of us it doesn't illuminate much. Although, maybe that's just the difficulty of quantum mechanics.

@@dylancope I have studied QM before. The issue is that its 5 minutes of QM. Maybe one of the most difficult to understand fields in all of academia and he wants to do it as fast as he can. Ok, watch your subscriber base fall away and only those that study the field will watch. His choice.

+ I am a student @ school in my final year (12th grade) + I'm not a native speaker - to be fair: I have a little prior knowledge since I'm very interested in QM & I chose it as my priority subject _______ Yet I understood everything quite well. Not sure what's wrong here. Only thing I could criticize is that the cat metaphor was kind of distractive

In forth you should already know ALL of this.

Just remember everything is very oversimplified

I'm in kindergarten and I already know all of this.

I haven't been born yet and I understand none of this

im a fetus and i have a PhD in quantum mechanics

click on the settings cogwheel, change video speed to slower, understand everything.

If you don't speak english then how did you type this comment??

May be you should learn to speak english?

@@RoboBoddicker He didn't say anyting about writing

To English speakers you probably talk fast.

there is no such thing as too much bass

It is not a guitar, it's a Contrabass.

That guitar is the sound of neurons being triggered into thinking deep thoughts.

I think they are launched at the exact same time from the same distant to the middle slit. This way, they must intercept the slit at the same time.

OK, My bad. I was so thrown off by change to cat (I don't know why, usually I don't mind), that my brain switched off. I Apologize for the stupid question, I have (hopefully) a smarter one. Has anyone did (I think they did, it is almost impossible to think that people would stop) three slit experiment, were the slits, are so close enough (probably at least half of the wavelength for the two outer slits), that the particle is forced to go through all three of them and interfere with itself, although a lot of information would be destroyed by interference from waves from 2 adjacent slits, perhaps some would survive to interfere with unchanged wave that is a result of the furthest slit "changing it to wave". I wonder how it would look like. I took in too much advanced Quantum Physics, and now thanks to you, I realize how bad I am at the basics. Back to Basics.