Man, I've been familiar with the Schrodinger's cat for a a long time now (like 2-4 years since I saw it being mentioned in a show I watched) but this is the first time I actually understood the proper context for that thought experiment. I did not expect it to be a means of discrediting an interpretation lol. The more you know.
Don't you feel like this theory could also relate to the question " if a tree falls in the middle of nowhere with no one around to observe it, does it make a sound?" What do you think?
@@natashambulo3510 To be honest what I think is no, it's not applicable for that question. My reason being is that it is already a well-established fact that things usually make some sort of sound whenever they hit something and whether we are there to observe it or not, it is easy to say that it did make a sound based on what we already know. The case for Schrödinger's cat isn't like this since there is a clear 50% chance that the cat is alive (or dead). So basically, it's a matter of how well the conditions of the thought experiment are in demonstrating the superposition of something. But well, if your question was asked in a time period in the past where the concept of sound wasn't well established yet, then your question may have been applicable for the Schrödinger's cat. Really interesting question though. Thanks for asking. I hope I was able to explain my opinion properly :)
@@colorx6030 I appreciate your opinion and that you actually responded. I was just speculating philosophically and wanted to know what you thought about it. So thank you
Pitch perfect! Great transition and extrapolation from the Maths to the interpretations! Too often I see these topics treated separately, when, just like you showed, they are all under the same continuum of calculus => experiments => interpretations => peer-review.
I have just watched Schrodinger's equation (no mention of time dependent or time independent) however, it was simply wonderful, as was this Heisenberg's paradox, as a consequence, I have subbed you Thank you, Professor Dave !!! Love from bloody Australia
I've never taken a physics class (yet), and the fact i almost understood what he was talking about goes to show how good of a teacher Dave is Also i thought heisenberg was a chemist
Probably not. I always thouht that in this mental experiment there is no photon interacting, therefore the superposition can be. Or, in a more mistical and phyloshopical aprox, observation is related with reality perceiving reality, and reality perceiving reality is something like consciousness
This is actually the copenhagen interpreters response to schrodinger beside that air particles may bump the radioactive material and make it's superposition state collapse
Heisenberg is pulled over on a highway. The cop gets out of the car and asks Heisenberg "do you know how fast you were going?!" and Heisenberg replies "no, but i know exactly where I am."
Hey Dave! Doing an episode on the uncertainty principle in Turkish and man - got a little confused. Watched a decent amount on it, and read some articles. Wanted to know your input. Here's what I got out of it - since everything is both wave and particle (de Broglie), this imposes the superposition principle - they can be in multiple places at once (or a probability) and their location is the sum of all the possibilities - until we measure or observe it; then the state collapses (like you mentioned and from what I understand). So the uncertainty principle is when you limit the superposition of location lets say (or decrease the possibility of the particle being in more places), then you increase the superposition of the momentum (when you get close to the heisenberg uncertainty limit). When it is said that the uncertainty principle is when you measure one, the other goes crazy is wrong I feel like - since the principle does not depend on an observer being there. But it is caused by you decreasing the possibility of superpositions? I saw the episode that Veritasium did, and he had a light passing through a slit, and as he made the slit smaller - at one point the light that was projected on the wall started expanding - where you are limiting position, so the uncertainty in momentum has to increase. So the act of knowing where the particle is doesn't cause the uncertainty, but limiting the places it can be (so the position is more certain) does? Does that sound right? Quantum dude.. Would appreciate your thoughts!
i think that sounds pretty reasonable! i'm not expert but it is definitely the crux of heisenberg that minimizing the uncertainty in one complementary parameter increases the uncertainty in the other. that is undeniably true. in terms of interpreting that, it gets a little trickier, but i believe that forcing a system to tell you particle-like information for one parameter, like precise location, must necessarily increase the wave-like character of the other parameter. so if you know exactly what the particle is doing, you can't know where it is, because knowing both simultaneously would make it strictly a particle, and it's not, it's a particle and a wave.
Hey man really appreciate the reply! Starting to make sense now. I also bumped into people saying that the result of slit experiment I mentioned is diffraction. So I concluded that when looked at from the wave point of view, the effect can be explained from Huygen's diffraction principle, but when we look at it from a particle perspective - it can be explained by the uncertainty principle. I really liked how you said that knowing where it is makes it a particle, and it is both a particle and a wave. Makes sense. Thanks again man, all the best!
There is a video on Physics Explained that goes into the math of the uncertainty principle, perhaps it will help you understand it too, I like videos that go into the math of this kind of stuff, makes it less abstract IMO (In My Opinion) I didn’t know if you already saw IMO before so just to limit porential confusion I put what it stood for too
Hey appreciate the reply. Already made the episode shortly after, been years now. Hope everything is well on your side brother, take care. @@naturegirl1999
What a roundabout way to explain the Heisenberg uncertainty principle! It follows from Planck's constant of action. Any two values that form this constant cannot fall below this constant between them, that's all. No need for particles, waves, probabilities etc. etc.
No, not "any two values". Any two complementary values, such as position/momentum, and energy/time, which are the two sets of values that matter in physics, and this is a modern physics series. So yes, there definitely is a need for all of those things.
I have a doubt. The photons will be interacting with the system whether or not we are looking right? Our eyes just happens to be in the way of some of the photons, so the system must have already collapsed into a reality whether we look at it or not.
but what if it didn't interact with the photon we cannot know for sure that is why it is in superposition and everything is probabilistic. IDK WHAT I"M SAYING EITHER but idk it kinda makes sense also doesn't make sense. this is fucking stupid
I know that the video is old, but there are two common misconceptions here: First of all the accepted solution for the Schrodinger paradox (in the Copenaghen interpretation) Is that the cat Is a macroscopic system so It causes the wave function collapse. The second Is on the Heisenberg physical interpretation: It seems to be that the effect of the noise caused by the photon could be far beyond the limit of hbar\2, but the articles Is really technic and i only have a Bachelor in physics so i can't understand it
In the Schrödinger’s cat idea, wouldn’t the radiation detector be able to act as an observer? Since the information of the atom decaying is causing something to happen, would that collapse the superposition? In that vein, wouldn’t the superposition immediately collapse whenever the emitted particle interacts with anything?
It's like the ratio of position to momentum has to stay the same so if you have more possible positions then you need less possible momentums to be in equilibrium but if you have more possible momentum you need less possible positions to be in equilibrium kind of like position and momentum are parts of the same thing in a certain ratio to each other. When you measure one or the other you get the particle property of the system which determines which aspect of the system will express itself as a wave so if you measure the position it will express the momentum more as a wave or vice versa. Just my thoughts as I'm trying to learn about it.
Absolutely fascinating content!! Does this imply that everything is inherently a wave and particle until observed? How does quantum understanding apply to the observation of the self? Does this imply that we are superimposed in a physical/wave state simultaneously? If so, is death a release of this observational constriction of our selves as ‘particles’?
Well, there is no firm consensus on how to interpret quantum mechanics! Even on the particle realm, let alone all the philosophical ramifications. But one day we may know more! And I hope to catch up to what other people know when I get some time.
You're going to have to know a lot of math to study physics seriously. Calculus, matrix mechanics, transforms, cross sections, etc. The best of luck to you :o)
to be honest I was in the same camp untill now... However, I am now with Scrodinger that such probabilistic nature shouldnt be natures way. Nature is concrete, it doesnt play dice. One such area where I wouldnt mind probabilistic operations are when we plan for the future, not predict the future.
unfortunately, all the data tells us that nature is indeed probabilistic on the most fundamental level! determinism is simply an emergent property of matter once we look at systems larger than a small molecule.
why the right side of Heisenberg's uncertainty principle contains h/4*pi as a constant. what is the explanation of the occurrence of this particular constant??
well, Planck's constant shows up in a ton of equations, it has something to do with quanta, or a way of describing the tiniest things possible, in a way that makes sense with our own man-made units. but as for the pi, i'm not sure! quantum mechanics is a tough nut to crack.
+ Harsh Singh It might be that the pi has to do with angular momentum? As in, Heisenberg's equation describes uncertainty of position/momentum (in any "direction", not just a straight vector)...
the thought experiment assigns the person outside the box as the observer, isolation from observation is what makes the superposition possible, it doesn't matter who or what is inside the box.
You can call anything you want an observer but the thought experiment deals specifically with an observer that has been isolated from the system. It is meant to explore the alleged absurdity of superposition.
@@ProfessorDaveExplains So,by not acknowledging the mechanism or any element that has an interaction with the atom, as an observer, is the thought experiment in the wrong, and by extend Schrödinger himself?
Wow! 👏You explained this so well and clearly. Once students get to know your videos, you will really become a popular channel. Probably, they look at your picture and they don’t know that you are really a great prof. Also some people don’t like the fact that you look like you are reading the script. May be you can think about it. I am only suggesting because I feel that not many students know that you have good information. I am sorry if I offended you. Good luck!
Why can't the decayed/not decayed atom stay in a state of superposition on it's own? I mean... as an end of the sequence? The cat may well be dead or alive with certainty, while the atom remains in superposition.
but the status of the cat is linked to the atomic event! if it's dead, the atom must have decayed, as only the decay will trigger the poison mechanism, and if it's alive, the atom must not have decayed. that's why schrodinger set it up that away, in an attempt to illustrate his perceived absurdity of superposition.
I don't see a real paradox here. The Geiger detector is actually an observer, that will either detect the emission of a particle inside the box or not. We simply do not know whether the atom has decayed (i.e. whether the cat is dead) until we open the box, but the cat will stay alive, until (unless) the atom has emitted a particle that has been measured by the detector. Saying that the cat is in a dead/alive superposition is like saying that an observer is in a superposition state before he actually observes a quantum phenomenon.
sure the detector could be considered an "observer", or even the cat, but those are separate questions. we are examining the situation using ourselves as the observer, and the superposition that results until we specifically take a measurement/look inside. that's the problem of measurement that drove some of those physicists up the wall, because to say that the cat is experiencing a different reality than we are simply by virtue of being inside the system is quite bizarre. i'm not sure how i feel about it myself!
I agree, once the detector measures a particle, the wave function collapses, the atom is not in a superposition state, and the cat which was alive until then, dies. Superposition does not continue beyond the quantum level.
What if the two cats are in to different time frames one in present time and other in a past time? Every time you check the particles potion you just reconfirming you are in present time. When you stop looking the particle goes back to a position it held in the past so your looking at a kind of time echo
Let's say every particle is not in a superposition, but a definite state, that we can't measure (because the experiment changes the state of the electron). If we knew precisely how does the photon (that we use to observe and it interacted with the particle before) alters the state of the system? If we knew it precisely, would that mean that we can calculate the exact state of the electron in at the exact time of the experiment? Seems a little bit misleading to think that just because we can't measure something, it's in a superposition. But I guess physicists know better.
Is it possible to have a probabilistic view of Quantum Mechanics while also agreeing with Schrodinger that the cat being both dead and alive is absurd?
But that's not the thought experiment, it regards a system that is isolated from observation, and the superposition associated with that system until it is observed.
I find myself agreeing with those in the camp of the cat is dead or alive until you look in the box. If quantum mechanics is fr governed my probabilities then I feel like a resolution to the paradox could be made such that “that cat may or may not be dead, who knows till you look, but damn bro the longer you wait the more likely it’s gonna be”
clearly cophenhegen interpretation states that the reality is much like a superposition of a numerous reality and we can only objerve or we can relate to it in any random way of relation only so reality is a stream of random variable and any interaction within any two physical reality is all exist out there we van see or realize any one of it.......................
I love your "check comprehension" I wish more youtube teachers would do this but I feel that it is to short for example say you have a formula at the end after "check comprehension" have say 10 questions (so it will sink in)kind of like a work sheet
Great video! I had a question if you don't mind: I'm having trouble visualising this principal. If I know the exact position of a stationary partical then according to the uncertainty principle, I can't know the momentum (mass*velocity). But if I know the exact stationary position, how can there be a momentum/velocity (Speed in given direction) since its stationary??? Is it more accurate to think along the lines of: As mass and velocity constitute momentum, that would mean I can know the exact position and velocity but not mass/(energy) or I can know the exact position and mass but not velocity of the partical? I'm quite sure there is some basic information I'm missing that's confusing me but explanation would be greatly appreciated! Thanks again for the videos!
hmm, good question! perhaps we are not regarding it as stationary, perhaps we are describing instantaneous position. but i also know time and energy are complementary variables just like position and momentum, so maybe there is a correlation there. but i'm not too sure!
@@ProfessorDaveExplains Thank you so much for you reply! I had the same thought regarding instantaneous position, if that's the case would it be more accurate to say you can't predict the particals next position or momentum from the information you have about the instantaneous position...? However, put the partical close to absolute zero and you could definitely know its stationary position and garentee it would have almost no velocity, so the original predicament still stands haha?!? Thanks again for your input and informative videos!
Greetings Dave this principle is heplful for quitting smoking, dropping cookie obessions...............as shared by Dr David Hawkins..............please explain this power thank you Kay La
I used to think this way when i was little. I was rather imaginative since i grew up alone pretty much. Before entering a different room. Before opening a door. Did it even exist until i seen it with my own eyes. Maybe not quite the same but my mind was always working. 😅
IMHO the trouble with this explanation and all other popular explanations of Schrodinger's Cat is that it doesn't give a convincing reason for why the atom and the cat must be in a superposition of states. From a naive observer's POV there is no reason to suspect a superposition of states, even if the the decay is random - it is just like everyday life. It needs to be linked back to the double slit expt. which essentially shows that the photon never went through just slit one or just slit two, the wave had to go through both or there wouldn't be an interference pattern over many trials. Thus it is the double slit expt that forces us to infer a superposition of states until there is a measurement, because otherwise there would be no interference.
Yes there is. If the atom is in a superposition, and that superposition is tied to the status of the cat, the cat is also in a superposition. The double slit experiment is a totally separate concept and is not directly linked to this one, which has nothing to do with interference whatsoever. What is depicted is verbatim the thought experiment as outlined by Schrodinger, so I'm not sure what you're talking about.
yes but you measure fast enough, it's like a movie. you can't tell the motion of an actor from looking at a still frame, but if you play it fast enough it's motion is inferred.
Dave. Lovely videos and my first time here. Dave I can't work out if the "act of observation" is meant metaphorically or literally in the Cat experiment or both? You seem to be suggesting it's the human bundle of atoms (photon entering the eye etc) actually alters the result. I don't understand how we can know something is in both states, since we could never make a record, observation of this. Is it a mathematical, probabilistic assumption? Scratch my head.
well that was the point of the thought experiment, schrodinger took the abstract concept of "observation" on the quantum realm and tethered to a concrete observation anyone can make in the macroscopic world, that is the cat being dead or alive. he meant for the notion of the cat being in a dead/alive superposition to seem absurd and discredit the copenhagen interpretation, so you are correct to find it confusing! as to the reality of the matter, it's very much still open to interpretation.
Problem, isn't the cat an observer? Also, wouldn't this mean if you put a human in there? They'd be both alive and dead. Or since they're observing it, what would happen? What about the apparatus? It's able to observe if there's decay. This is all very confusing. I think I'm gonna stick to normal mechanics for now.
Hi, Prof. Dave! I've a doubt: how does "h/4pi" come into the mathematical inequation of the Uncertainty Principle i.e. how does the inequation explain the uncertainty? Also, why does the product of the uncertainties in the position and momentum of the particle represent that when one of the 2 variables is known, the value of the other becomes more and more uncertain?
oh man, as for how pi gets in there i wish i knew! it's so abstract and mysterious to me. but the uncertainties are found as a product because they are inversely proportional. if one uncertainty doubles the other can be cut in half, they have a constant product.
Thanks, Professor! I'm trying to understand the formula to remember it better, as in a recent test, I wrote the constant term as "h/2pi" by an oversight!
God is both wave & particle or as described in Saivite Agamic philosophy Siva is both Nada & Bindu respectively. As per, first Hermetic principle "The All is mind; The Universe is Mental(Consciousness)". Physicality and separation are mere illusions "created" by the Great Cosmic Prankster aka God. Ironically, one who is spiritually enlightened is described as attaining immortality, by being in state of "living dead" so to speak, somewhat comparable to Schrödinger's cat. 😁😁😁
In the Schrodinger's box you stated there was no observer with the box closed, this is untrue, the detector that sets off the poison vail is an observer and so the cat would be dead.
I don't think that Schrodinger's cat experiment debunks the Copenhagen interpretation in any way and it's just rather an interesting thought experiment on reality. The cat cannot be alive and dead at the same time in the physical world. It's either dead, or alive. What if a human was put in there instead and had a radio to talk to the scientist? If he stops receiving transmissions, the guy inside is dead.
About the Schrodinger paradox: couldn't the radiation detector also be considered as "observing" the system since as you said even detecting a single photon is considered observing?
Simply speaking, is it correct to say that "superposition" is a certain amount of space , let's say a box, within which there is a certain probability the atom is located at a certain time? This implies that it is impossible to know the exact position of the atom, until we observe it? Does the act of observing give us an exact position, or will it continue to be uncertain even once observed? The concept of the uncertainty of the position is quite understandable to me, which is why I'm trying to make out why it was necessary to make the cat example. I mean, we know that because of the superposition principle, we cannot know the position, so why not just stop there?
well a superposition doesn't have to imply position only, it's just a blending of two states. it could be spin, or any other parameter, but yes position is such a parameter. if a particle is in such a superposition, we can't know its exact position until we observe it, and in fact some believe that it truly does not even have a precise position until it is observed. schrodinger found this absurd, and the thought experiment with the cat was supposed to tether superposition to a macroscopic object so as to illustrate its absurdity, because a particle in a superposition is abstract, but an alive/dead cat is harder to brush aside. but we still don't have consensus as to how to interpret this stuff!
+ Grigory Personally, I find the idea of "superposition" too much of a "shortcut" way to explain what happens with Wave-particle experiments. It is a bit too "man-made", just like the many worlds interpretation, btw. QM is not like Relativity and its clean-cut rationalisation+calculations+predictions. All interpretations of QM are downright disappointing or quite unsatisfying at best. But hey, that's the only bone that was left for Modern Physics to chew on (although, Fluid dynamics is also another mind blowing one): let's just enjoy the pondering...
@@ProfessorDaveExplains thank you sir . Your video helped me a lot to prepare for my seminar. I watch your video several times and was able to understand it clearly 😊
Surely if a cat is able to observe the inside of the box then the interior is in its super position state and there for proceeds normally and kills the cat? Idek if I’m making sense - this stuff melts my brain
Not to be weird or anything but isn't the cat technically an observer? Just seems important since you can reasonably consider it to have two eyes capable of seeing natural phenomenon. I guess classifying this experiment and the state of physics study for their time as unnatural would be an argument that progresses from Schrodinger's cat, or the Heisenberg principle even?
You could label the cat as an observer, but this thought experiment is specific to the act of observation for someone outside of the box! The system has to be isolated from observation for the superposition principle to apply.
I am not saying that i would, but if you were to put someone in a box and no one ever saw them again they could be considered dead or alive right? Seems to be so Columbus like ideas. Just because you didn't discover it didn't mean it hasn't happened.
This thought experiment is about quantum superposition and the role of the observer in quantum events. You are talking about leaving someone in a box to die. Those are not related whatsoever.
The problem is, that people don't know, that when you are talking about "an observer" in quantum physics, we are not talking about humans, but any interactions between particles, and as soon the interact, the waves collapses. So yeah, the cat is never dead and alive, just dead or alive, as soon as the single atoms wave collapses, and emits an particle, the cat is dead, and stays dead.
@@ProfessorDaveExplains Not completely, the particles retains their probabilities. To quote Quantum Mechanics - Course of Theoretical Physics by L.D. Landau and E.M. Lifshitz: "By measurement, in quantum mechanics, we understand any process of interaction between classical and quantum objects, occuring apart from and independently of any observer. The importance of the concept of measurement in quantum mechanics was elucidated by N. Bohr." Also there is no soul controlling the brain, it's pure mechanical, so any talk of choice of observance is meaningless.
Certainly, an inert measuring device is an observer just as a human can be. I just know that Copenhagen treats the alive/dead superposition as a reality. But it's all pretty bonkers to me regardless!
I don't see the issue. Its like you see a star, but the star exploded some million years ago. The light just hasn't reached us. I feel that too many things in advanced physics (quantum, relativity) are way too constrained by light, just because that is how we see with our own eyes
Why isn't the device with the ability to detect radiation counted as the observer. If the device detects radiation then it has observed the state of the atom.
@@ProfessorDaveExplains Hi. Thanks for taking the time to respond. I thought the point was that the act of observation had an impact on the state of the observed atom. I'm obviously missing something because I wouldn't be so arrogant to argue with these scientists, but my understanding so far is: We could propose 3 observers. The device, myself, a friend of mine in the next room. The device observes the decay and collapses the probabilities and the cat is dead. I open the box and see the cat is dead. At this point, my friend in the next room still hasn't observed if the cat is dead. I don't understand why my observation of what's in the box is any more significant than the device observing the radiation from inside the box. And even if I observed the cat, is the entire room now in some sort of superstate relative to my friend in the next room that hasn't observed any of this yet?
Ugh, sorry, at the time that I made this one I probably would have been able to answer, now my brain is mush and I can't wrap my head around it either. I know that Copenhagen would propose that the whole system is in a superposition until we observe it, but not necessarily that the act of observation effects the system, it just forces it to collapse into a particular eigenstate or something or other. Furthermore the thought experiment is meant to discredit Copenhagen, so it should be confusing. I'm gonna try and make more physics tutorials later this year, hopefully I can elucidate this and other aspects of QM.
4 года назад
So what happened?? I love cats so killing a cat feaks me out. so what was the result of the exsperiment please??
This was never a real experiment that someone performed, just a thought experiment originally devised to point out how unintuitive quantum mechanics can be.
2:50 Congratulations, FINALLY a video on youtube that explains that the 'observer' in the experiment is not a 'soul' or a 'consciousness', etc...
There isn't such thing as unconscious observation now, is there? Lol!
Thanks!
Man, I've been familiar with the Schrodinger's cat for a a long time now (like 2-4 years since I saw it being mentioned in a show I watched) but this is the first time I actually understood the proper context for that thought experiment. I did not expect it to be a means of discrediting an interpretation lol. The more you know.
Another big bang theory fan? I've been recently going through the same thing, I love the fact I now know the full context of this :)
Don't you feel like this theory could also relate to the question " if a tree falls in the middle of nowhere with no one around to observe it, does it make a sound?" What do you think?
@@natashambulo3510 To be honest what I think is no, it's not applicable for that question. My reason being is that it is already a well-established fact that things usually make some sort of sound whenever they hit something and whether we are there to observe it or not, it is easy to say that it did make a sound based on what we already know.
The case for Schrödinger's cat isn't like this since there is a clear 50% chance that the cat is alive (or dead). So basically, it's a matter of how well the conditions of the thought experiment are in demonstrating the superposition of something.
But well, if your question was asked in a time period in the past where the concept of sound wasn't well established yet, then your question may have been applicable for the Schrödinger's cat.
Really interesting question though. Thanks for asking. I hope I was able to explain my opinion properly :)
@@colorx6030 I appreciate your opinion and that you actually responded. I was just speculating philosophically and wanted to know what you thought about it. So thank you
Schrodinger overlooked that the fact that there must be NINE decays--He should have used a dog!
zing!
lmfao
@@yarakharam5343 That's the kind of answer which can help you beat Trump in the presidential elections.
I see that Americans won't be certain about anything until they stop choosing between Blue or Red
Why nine?
Pitch perfect!
Great transition and extrapolation from the Maths to the interpretations!
Too often I see these topics treated separately, when, just like you showed, they are all under the same continuum of calculus => experiments => interpretations => peer-review.
I have just watched Schrodinger's equation (no mention of time dependent or time independent) however, it was simply wonderful, as was this Heisenberg's paradox, as a consequence, I have subbed you
Thank you, Professor Dave !!!
Love from bloody Australia
I've never taken a physics class (yet), and the fact i almost understood what he was talking about goes to show how good of a teacher Dave is
Also i thought heisenberg was a chemist
U r the best youtuber of science I've ever seen..
Yep!!
Heisenberg: You're goddamn right!
I like your simple and casual way of explanation professor!
Well after a year of keeping this stuff in my mind i think i'm finally making sense of it. I love these aha moments! :D
Stole this off my brain mate! Can't agree more :D
try more and you lose your mind slowly............my friend.......
Is the cat dead or alive?
Schrodinger: YES
Does the cat not act as an observer?...
that's a whole separate question! we are just examining our own perception.
Just imagine the cat as being blind.
As far as superposition is concerned, maybe not!
Probably not. I always thouht that in this mental experiment there is no photon interacting, therefore the superposition can be. Or, in a more mistical and phyloshopical aprox, observation is related with reality perceiving reality, and reality perceiving reality is something like consciousness
This is actually the copenhagen interpreters response to schrodinger beside that air particles may bump the radioactive material and make it's superposition state collapse
Heisenberg is pulled over on a highway. The cop gets out of the car and asks Heisenberg "do you know how fast you were going?!" and Heisenberg replies "no, but i know exactly where I am."
Hey Dave! Doing an episode on the uncertainty principle in Turkish and man - got a little confused. Watched a decent amount on it, and read some articles. Wanted to know your input.
Here's what I got out of it - since everything is both wave and particle (de Broglie), this imposes the superposition principle - they can be in multiple places at once (or a probability) and their location is the sum of all the possibilities - until we measure or observe it; then the state collapses (like you mentioned and from what I understand).
So the uncertainty principle is when you limit the superposition of location lets say (or decrease the possibility of the particle being in more places), then you increase the superposition of the momentum (when you get close to the heisenberg uncertainty limit). When it is said that the uncertainty principle is when you measure one, the other goes crazy is wrong I feel like - since the principle does not depend on an observer being there. But it is caused by you decreasing the possibility of superpositions? I saw the episode that Veritasium did, and he had a light passing through a slit, and as he made the slit smaller - at one point the light that was projected on the wall started expanding - where you are limiting position, so the uncertainty in momentum has to increase. So the act of knowing where the particle is doesn't cause the uncertainty, but limiting the places it can be (so the position is more certain) does? Does that sound right?
Quantum dude.. Would appreciate your thoughts!
i think that sounds pretty reasonable! i'm not expert but it is definitely the crux of heisenberg that minimizing the uncertainty in one complementary parameter increases the uncertainty in the other. that is undeniably true. in terms of interpreting that, it gets a little trickier, but i believe that forcing a system to tell you particle-like information for one parameter, like precise location, must necessarily increase the wave-like character of the other parameter. so if you know exactly what the particle is doing, you can't know where it is, because knowing both simultaneously would make it strictly a particle, and it's not, it's a particle and a wave.
Hey man really appreciate the reply! Starting to make sense now.
I also bumped into people saying that the result of slit experiment I mentioned is diffraction. So I concluded that when looked at from the wave point of view, the effect can be explained from Huygen's diffraction principle, but when we look at it from a particle perspective - it can be explained by the uncertainty principle. I really liked how you said that knowing where it is makes it a particle, and it is both a particle and a wave. Makes sense. Thanks again man, all the best!
There is a video on Physics Explained that goes into the math of the uncertainty principle, perhaps it will help you understand it too, I like videos that go into the math of this kind of stuff, makes it less abstract IMO (In My Opinion) I didn’t know if you already saw IMO before so just to limit porential confusion I put what it stood for too
Hey appreciate the reply. Already made the episode shortly after, been years now. Hope everything is well on your side brother, take care. @@naturegirl1999
What a roundabout way to explain the Heisenberg uncertainty principle! It follows from Planck's constant of action. Any two values that form this constant cannot fall below this constant between them, that's all. No need for particles, waves, probabilities etc. etc.
No, not "any two values". Any two complementary values, such as position/momentum, and energy/time, which are the two sets of values that matter in physics, and this is a modern physics series. So yes, there definitely is a need for all of those things.
@@ProfessorDaveExplains That's what I meant. Maybe I didn't express it the right way.
I have a doubt. The photons will be interacting with the system whether or not we are looking right? Our eyes just happens to be in the way of some of the photons, so the system must have already collapsed into a reality whether we look at it or not.
but what if it didn't interact with the photon we cannot know for sure that is why it is in superposition and everything is probabilistic. IDK WHAT I"M SAYING EITHER but idk it kinda makes sense also doesn't make sense. this is fucking stupid
6:05: They do have precise position and momentum ,but they both can not be measured at the same time.
That is the first time i understand what Schrödingers Cat acctually trys to convey! thanks Dave!
I know that the video is old, but there are two common misconceptions here:
First of all the accepted solution for the Schrodinger paradox (in the Copenaghen interpretation) Is that the cat Is a macroscopic system so It causes the wave function collapse.
The second Is on the Heisenberg physical interpretation: It seems to be that the effect of the noise caused by the photon could be far beyond the limit of hbar\2, but the articles Is really technic and i only have a Bachelor in physics so i can't understand it
Hello do you understand quantum mechanics,? If so would you care to clear one of my doubt.
In the Schrödinger’s cat idea, wouldn’t the radiation detector be able to act as an observer? Since the information of the atom decaying is causing something to happen, would that collapse the superposition?
In that vein, wouldn’t the superposition immediately collapse whenever the emitted particle interacts with anything?
The cat would also scream
The experiment kinda tries to point towards the fact that there must not be any observation made at all
Bro said let’s finish up with Heisenberg and proceeded to not
That's the next tutorial, kiddo. Go to the playlist.
@@ProfessorDaveExplains this is fame, I may need to start looking for bodyguards
Truly, it is all about the wave.
jp photon no it's about the base
6:06 conjugate complementary variables
It's like the ratio of position to momentum has to stay the same so if you have more possible positions then you need less possible momentums to be in equilibrium but if you have more possible momentum you need less possible positions to be in equilibrium kind of like position and momentum are parts of the same thing in a certain ratio to each other. When you measure one or the other you get the particle property of the system which determines which aspect of the system will express itself as a wave so if you measure the position it will express the momentum more as a wave or vice versa. Just my thoughts as I'm trying to learn about it.
dave sir u gonna be a star
Absolutely fascinating content!! Does this imply that everything is inherently a wave and particle until observed? How does quantum understanding apply to the observation of the self? Does this imply that we are superimposed in a physical/wave state simultaneously? If so, is death a release of this observational constriction of our selves as ‘particles’?
Well, there is no firm consensus on how to interpret quantum mechanics! Even on the particle realm, let alone all the philosophical ramifications. But one day we may know more! And I hope to catch up to what other people know when I get some time.
That's where. LHC emerged
you're making me want to become a physicist
You're going to have to know a lot of math to study physics seriously. Calculus, matrix mechanics, transforms, cross sections, etc. The best of luck to you :o)
1:56 When it's gotcha, it's gotcha!
to be honest I was in the same camp untill now... However, I am now with Scrodinger that such probabilistic nature shouldnt be natures way. Nature is concrete, it doesnt play dice. One such area where I wouldnt mind probabilistic operations are when we plan for the future, not predict the future.
unfortunately, all the data tells us that nature is indeed probabilistic on the most fundamental level! determinism is simply an emergent property of matter once we look at systems larger than a small molecule.
nice explanation
why the right side of Heisenberg's uncertainty principle contains h/4*pi as a constant. what is the explanation of the occurrence of this particular constant??
well, Planck's constant shows up in a ton of equations, it has something to do with quanta, or a way of describing the tiniest things possible, in a way that makes sense with our own man-made units. but as for the pi, i'm not sure! quantum mechanics is a tough nut to crack.
+ Harsh Singh It might be that the pi has to do with angular momentum? As in, Heisenberg's equation describes uncertainty of position/momentum (in any "direction", not just a straight vector)...
Professor, I like the flute in the introduction of your videos. Do not change it. It is your identity.😊
If the mechanism can detect whether or not, the atom is decaying. Doesn't it make it an "observer"?
the thought experiment assigns the person outside the box as the observer, isolation from observation is what makes the superposition possible, it doesn't matter who or what is inside the box.
@@ProfessorDaveExplains So, only humans or sentient beings that are able to conduct those observations can be observers?
You can call anything you want an observer but the thought experiment deals specifically with an observer that has been isolated from the system. It is meant to explore the alleged absurdity of superposition.
@@ProfessorDaveExplains So,by not acknowledging the mechanism or any element that has an interaction with the atom, as an observer, is the thought experiment in the wrong, and by extend Schrödinger himself?
No, it just examines the perspective of an observer isolated from the system, that’s all.
Dear sir what is the preferred formula. Sometimes we write uncertainty product as 'h/2π' and sometimes only 'h'.
no if only h that is h bar, h with a line through the top, which represents h over 2 pi
Wow! 👏You explained this so well and clearly. Once students get to know your videos, you will really become a popular channel. Probably, they look at your picture and they don’t know that you are really a great prof. Also some people don’t like the fact that you look like you are reading the script. May be you can think about it. I am only suggesting because I feel that not many students know that you have good information. I am sorry if I offended you. Good luck!
Why can't the decayed/not decayed atom stay in a state of superposition on it's own? I mean... as an end of the sequence? The cat may well be dead or alive with certainty, while the atom remains in superposition.
but the status of the cat is linked to the atomic event! if it's dead, the atom must have decayed, as only the decay will trigger the poison mechanism, and if it's alive, the atom must not have decayed. that's why schrodinger set it up that away, in an attempt to illustrate his perceived absurdity of superposition.
Thank you for the explanation
Thanks alot professor Dave
Omg, so every time I look at the night sky, I'm affecting the system?
Good explanations thank u so much.
Well done Dave
Can you please do a video on the mathematics of Fourier Transforms with respect to wave function collapse?
I don't see a real paradox here. The Geiger detector is actually an observer, that will either detect the emission of a particle inside the box or not. We simply do not know whether the atom has decayed (i.e. whether the cat is dead) until we open the box, but the cat will stay alive, until (unless) the atom has emitted a particle that has been measured by the detector. Saying that the cat is in a dead/alive superposition is like saying that an observer is in a superposition state before he actually observes a quantum phenomenon.
sure the detector could be considered an "observer", or even the cat, but those are separate questions. we are examining the situation using ourselves as the observer, and the superposition that results until we specifically take a measurement/look inside. that's the problem of measurement that drove some of those physicists up the wall, because to say that the cat is experiencing a different reality than we are simply by virtue of being inside the system is quite bizarre. i'm not sure how i feel about it myself!
I agree, once the detector measures a particle, the wave function collapses, the atom is not in a superposition state, and the cat which was alive until then, dies. Superposition does not continue beyond the quantum level.
What if the two cats are in to different time frames one in present time and other in a past time? Every time you check the particles potion you just reconfirming you are in present time. When you stop looking the particle goes back to a position it held in the past so your looking at a kind of time echo
Let's say every particle is not in a superposition, but a definite state, that we can't measure (because the experiment changes the state of the electron). If we knew precisely how does the photon (that we use to observe and it interacted with the particle before) alters the state of the system? If we knew it precisely, would that mean that we can calculate the exact state of the electron in at the exact time of the experiment?
Seems a little bit misleading to think that just because we can't measure something, it's in a superposition. But I guess physicists know better.
you're a lifesaver man
Is it possible to have a probabilistic view of Quantum Mechanics while also agreeing with Schrodinger that the cat being both dead and alive is absurd?
I suppose no one was thoughtful enough to consider that the cat is a relevant observer?
But that's not the thought experiment, it regards a system that is isolated from observation, and the superposition associated with that system until it is observed.
Hisenberg has the name and face of a mad scientist super villain.
I find myself agreeing with those in the camp of the cat is dead or alive until you look in the box. If quantum mechanics is fr governed my probabilities then I feel like a resolution to the paradox could be made such that “that cat may or may not be dead, who knows till you look, but damn bro the longer you wait the more likely it’s gonna be”
clearly cophenhegen interpretation states that the reality is much like a superposition of a numerous reality and we can only objerve or we can relate to it in any random way of relation only so reality is a stream of random variable and any interaction within any two physical reality is all exist out there we van see or realize any one of it.......................
I love your "check comprehension" I wish more youtube teachers would do this but I feel that it is to short
for example say you have a formula at the end after "check comprehension" have say 10 questions (so it will sink in)kind of like a work sheet
Great video! I had a question if you don't mind: I'm having trouble visualising this principal. If I know the exact position of a stationary partical then according to the uncertainty principle, I can't know the momentum (mass*velocity). But if I know the exact stationary position, how can there be a momentum/velocity (Speed in given direction) since its stationary??? Is it more accurate to think along the lines of: As mass and velocity constitute momentum, that would mean I can know the exact position and velocity but not mass/(energy) or I can know the exact position and mass but not velocity of the partical? I'm quite sure there is some basic information I'm missing that's confusing me but explanation would be greatly appreciated! Thanks again for the videos!
hmm, good question! perhaps we are not regarding it as stationary, perhaps we are describing instantaneous position. but i also know time and energy are complementary variables just like position and momentum, so maybe there is a correlation there. but i'm not too sure!
@@ProfessorDaveExplains Thank you so much for you reply! I had the same thought regarding instantaneous position, if that's the case would it be more accurate to say you can't predict the particals next position or momentum from the information you have about the instantaneous position...? However, put the partical close to absolute zero and you could definitely know its stationary position and garentee it would have almost no velocity, so the original predicament still stands haha?!? Thanks again for your input and informative videos!
Greetings Dave this principle is heplful for quitting smoking, dropping cookie obessions...............as shared by Dr David Hawkins..............please explain this power thank you Kay La
Is there not some confusion here between the Uncertainty Principle and the Observer effect?
I used to think this way when i was little. I was rather imaginative since i grew up alone pretty much. Before entering a different room. Before opening a door. Did it even exist until i seen it with my own eyes. Maybe not quite the same but my mind was always working. 😅
I like your opening 😊
IMHO the trouble with this explanation and all other popular explanations of Schrodinger's Cat is that it doesn't give a convincing reason for why the atom and the cat must be in a superposition of states. From a naive observer's POV there is no reason to suspect a superposition of states, even if the the decay is random - it is just like everyday life. It needs to be linked back to the double slit expt. which essentially shows that the photon never went through just slit one or just slit two, the wave had to go through both or there wouldn't be an interference pattern over many trials. Thus it is the double slit expt that forces us to infer a superposition of states until there is a measurement, because otherwise there would be no interference.
Yes there is. If the atom is in a superposition, and that superposition is tied to the status of the cat, the cat is also in a superposition. The double slit experiment is a totally separate concept and is not directly linked to this one, which has nothing to do with interference whatsoever. What is depicted is verbatim the thought experiment as outlined by Schrodinger, so I'm not sure what you're talking about.
Sir will you please elaborate schrodinger wave equation .....
"Durrrr reality depends on my observation of it. If a tree falls and nobody sees, it didn't fall." -arrogant chodes
Schrödingers Cat 🐈
Tibby, or not Tibby, that is the question!
Heisenbergs Cat 🐈 is probably somewhere around here.
how does pie gett jntwo the equation ¿¿¿¿¿¿
Pie only is to do withé circlê ¿¿¿¿
yes but you measure fast enough, it's like a movie. you can't tell the motion of an actor from looking at a still frame, but if you play it fast enough it's motion is inferred.
Dave. Lovely videos and my first time here. Dave I can't work out if the "act of observation" is meant metaphorically or literally in the Cat experiment or both? You seem to be suggesting it's the human bundle of atoms (photon entering the eye etc) actually alters the result. I don't understand how we can know something is in both states, since we could never make a record, observation of this. Is it a mathematical, probabilistic assumption? Scratch my head.
well that was the point of the thought experiment, schrodinger took the abstract concept of "observation" on the quantum realm and tethered to a concrete observation anyone can make in the macroscopic world, that is the cat being dead or alive. he meant for the notion of the cat being in a dead/alive superposition to seem absurd and discredit the copenhagen interpretation, so you are correct to find it confusing! as to the reality of the matter, it's very much still open to interpretation.
Problem, isn't the cat an observer? Also, wouldn't this mean if you put a human in there? They'd be both alive and dead. Or since they're observing it, what would happen? What about the apparatus? It's able to observe if there's decay. This is all very confusing. I think I'm gonna stick to normal mechanics for now.
Please do not forget its Fourier transform Energy versus time
Hi, Prof. Dave! I've a doubt: how does "h/4pi" come into the mathematical inequation of the Uncertainty Principle i.e. how does the inequation explain the uncertainty? Also, why does the product of the uncertainties in the position and momentum of the particle represent that when one of the 2 variables is known, the value of the other becomes more and more uncertain?
oh man, as for how pi gets in there i wish i knew! it's so abstract and mysterious to me. but the uncertainties are found as a product because they are inversely proportional. if one uncertainty doubles the other can be cut in half, they have a constant product.
Thanks, Professor! I'm trying to understand the formula to remember it better, as in a recent test, I wrote the constant term as "h/2pi" by an oversight!
God is both wave & particle or as described in Saivite Agamic philosophy Siva is both Nada & Bindu respectively.
As per, first Hermetic principle "The All is mind; The Universe is Mental(Consciousness)". Physicality and separation are mere illusions "created" by the Great Cosmic Prankster aka God.
Ironically, one who is spiritually enlightened is described as attaining immortality, by being in state of "living dead" so to speak, somewhat comparable to Schrödinger's cat. 😁😁😁
So Prof, basically the person who should be given credit for the cat-box experiment is Copenhagen.
Copenhagen is the capital of Denmark.
hello guys ! does anyone know about best mcqs books for inorganic chemistry?
In the Schrodinger's box you stated there was no observer with the box closed, this is untrue, the detector that sets off the poison vail is an observer and so the cat would be dead.
The thought experiment is from the perspective of a human person outside of the box.
I don't think that Schrodinger's cat experiment debunks the Copenhagen interpretation in any way and it's just rather an interesting thought experiment on reality. The cat cannot be alive and dead at the same time in the physical world. It's either dead, or alive. What if a human was put in there instead and had a radio to talk to the scientist? If he stops receiving transmissions, the guy inside is dead.
About the Schrodinger paradox: couldn't the radiation detector also be considered as "observing" the system since as you said even detecting a single photon is considered observing?
it's a thought experiment. Let just say it's not even if it is
Simply speaking, is it correct to say that "superposition" is a certain amount of space , let's say a box, within which there is a certain probability the atom is located at a certain time? This implies that it is impossible to know the exact position of the atom, until we observe it? Does the act of observing give us an exact position, or will it continue to be uncertain even once observed? The concept of the uncertainty of the position is quite understandable to me, which is why I'm trying to make out why it was necessary to make the cat example. I mean, we know that because of the superposition principle, we cannot know the position, so why not just stop there?
well a superposition doesn't have to imply position only, it's just a blending of two states. it could be spin, or any other parameter, but yes position is such a parameter. if a particle is in such a superposition, we can't know its exact position until we observe it, and in fact some believe that it truly does not even have a precise position until it is observed. schrodinger found this absurd, and the thought experiment with the cat was supposed to tether superposition to a macroscopic object so as to illustrate its absurdity, because a particle in a superposition is abstract, but an alive/dead cat is harder to brush aside. but we still don't have consensus as to how to interpret this stuff!
+ Grigory Personally, I find the idea of "superposition" too much of a "shortcut" way to explain what happens with Wave-particle experiments. It is a bit too "man-made", just like the many worlds interpretation, btw.
QM is not like Relativity and its clean-cut rationalisation+calculations+predictions. All interpretations of QM are downright disappointing or quite unsatisfying at best.
But hey, that's the only bone that was left for Modern Physics to chew on (although, Fluid dynamics is also another mind blowing one): let's just enjoy the pondering...
can anyone solve my confusion! what's the relation between the heigenberg's principle and the schrodinger's cat experiment?
Well you could watch this video you're commenting on and find out.
@@ProfessorDaveExplains thank you sir . Your video helped me a lot to prepare for my seminar. I watch your video several times and was able to understand it clearly 😊
Surely if a cat is able to observe the inside of the box then the interior is in its super position state and there for proceeds normally and kills the cat? Idek if I’m making sense - this stuff melts my brain
But the cat is a totally different observer, for whom there is no superposition. The thought experiment is for someone outside of the box.
@@ProfessorDaveExplains I am lost
👍👍👍
Not to be weird or anything but isn't the cat technically an observer? Just seems important since you can reasonably consider it to have two eyes capable of seeing natural phenomenon.
I guess classifying this experiment and the state of physics study for their time as unnatural would be an argument that progresses from Schrodinger's cat, or the Heisenberg principle even?
You could label the cat as an observer, but this thought experiment is specific to the act of observation for someone outside of the box! The system has to be isolated from observation for the superposition principle to apply.
Professor Dave Explains Oh okay! Gotcha
How do we compensate for it?
I still has to understand the heisenberg uncertainty principle, what kind of measurement is he talking about?
I am not saying that i would, but if you were to put someone in a box and no one ever saw them again they could be considered dead or alive right? Seems to be so Columbus like ideas. Just because you didn't discover it didn't mean it hasn't happened.
That has nothing to do with this topic at all.
that is exactly what the experiment says.
This thought experiment is about quantum superposition and the role of the observer in quantum events. You are talking about leaving someone in a box to die. Those are not related whatsoever.
So, the superposition of atom implies the superposition of dead/alive cat?
The problem is, that people don't know, that when you are talking about "an observer" in quantum physics, we are not talking about humans, but any interactions between particles, and as soon the interact, the waves collapses. So yeah, the cat is never dead and alive, just dead or alive, as soon as the single atoms wave collapses, and emits an particle, the cat is dead, and stays dead.
But that would be completely deterministic. I believe the Copenhagen interpretation doesn't agree with you.
@@ProfessorDaveExplains Not completely, the particles retains their probabilities. To quote Quantum Mechanics - Course of Theoretical Physics by L.D. Landau and E.M. Lifshitz: "By measurement, in quantum mechanics, we understand any process of interaction between classical and quantum objects, occuring apart from and independently of any observer. The importance of the concept of measurement in quantum mechanics was elucidated by N. Bohr."
Also there is no soul controlling the brain, it's pure mechanical, so any talk of choice of observance is meaningless.
Certainly, an inert measuring device is an observer just as a human can be. I just know that Copenhagen treats the alive/dead superposition as a reality. But it's all pretty bonkers to me regardless!
I don't see the issue. Its like you see a star, but the star exploded some million years ago. The light just hasn't reached us. I feel that too many things in advanced physics (quantum, relativity) are way too constrained by light, just because that is how we see with our own eyes
What about the cat observing itself and the contents of the box
totally separate thought experiment, we are talking about an event that is isolated from observation.
Does this mean that the radioactive atom and the cat are entangled?
Well just put a live camera in the box :,)
The odds of me understanding this tutorial is probabalistic even if I use the shroderinger equation the location of understanding it is zero
I'm uncertain that I understand this.
Came to check abt the cat comments 😂😂
Awesome
Your explain is nice. We need translate to Arabic
الهسيشنتصع بىيت فههسيمبتا يباستشةة بهصثم تررهي مشسن تبجذض ةرسع شمنسه بةقنتن
Why isn't the device with the ability to detect radiation counted as the observer. If the device detects radiation then it has observed the state of the atom.
Doesn't matter, it's inside the box and we aren't, our observation determines our perception of the cat.
@@ProfessorDaveExplains Hi. Thanks for taking the time to respond.
I thought the point was that the act of observation had an impact on the state of the observed atom. I'm obviously missing something because I wouldn't be so arrogant to argue with these scientists, but my understanding so far is:
We could propose 3 observers. The device, myself, a friend of mine in the next room.
The device observes the decay and collapses the probabilities and the cat is dead.
I open the box and see the cat is dead.
At this point, my friend in the next room still hasn't observed if the cat is dead.
I don't understand why my observation of what's in the box is any more significant than the device observing the radiation from inside the box. And even if I observed the cat, is the entire room now in some sort of superstate relative to my friend in the next room that hasn't observed any of this yet?
Ugh, sorry, at the time that I made this one I probably would have been able to answer, now my brain is mush and I can't wrap my head around it either. I know that Copenhagen would propose that the whole system is in a superposition until we observe it, but not necessarily that the act of observation effects the system, it just forces it to collapse into a particular eigenstate or something or other. Furthermore the thought experiment is meant to discredit Copenhagen, so it should be confusing. I'm gonna try and make more physics tutorials later this year, hopefully I can elucidate this and other aspects of QM.
So what happened?? I love cats so killing a cat feaks me out. so what was the result of the exsperiment please??
This was never a real experiment that someone performed, just a thought experiment originally devised to point out how unintuitive quantum mechanics can be.
observation is not passive - thats deep
Professor, If we replaced Cat with camera, what will we see?
a very good question! i suppose we still take the moment of observation as being the moment we look at the footage. but who knows!
And whatelse if that was recorder camera? The past cannot change, can we?
The problem is that we are using the logic of classical physics for the rules of quantum mechanics. That doesn't work.
why don't found tranzliation to Arabic
somebody has to submit it