Your statement seems off. It would make sense if you said it was difficult and yet concise and precise. Saying he explained physics easily and yet it was concise and precise is extremely wrong. It makes no sense to add the yet.
"Each idea has burrowed its way into the subconscious of people who are interested in science, but aren't quantum experts." - I love that wording, for some reason....
Dr. Lincoln does an outstanding job of breaking down some of the nebulous aspects of Quantum Mechanics without talking over his audience or interjecting silly metaphors. He even presents the various main theories on the collapse of the wave function probabilities without imposing his opinion on the discussion. A lot of grade 12 physics and first year university instructors could really use a refresher on how to introduce this subject matter. They could help students start to understand the concepts without scaring so many of them out of the field before they even really get started. Worth a look. Good for Fermilab for bringing science education out of the lab and classroom to the masses.
This is quite hard to believe as statictical mechanics and thermodunamics is standardly taught only after classical mechanics which is is at least one semester alone. Not mentioning that quantum mechanics is taught after classical mechanics and electromagnetism as a minimum which is 1 semester each as a minimum.
I didn't realize at the time, and that was a long time ago that I guess I was sort of introduced to "quanta." Must have been in the 2nd or 3rd grade. It was a poem that went like this: Little drops of water Little grains of sand Make the mighty ocean And the pleasant land Thus the little minutes Humble though they be Make the mighty ages Of eternity.
@@MichaelGonzales-by1eo > At the time I posted this a year ago, I couldn't remember the author's name; only the poem by rote. Second graders usually don't remember who wrote or composed anything. The author is Julia Abigail Carney, a Boston teacher. It was written in 1845 in Boston. The title is "Little Things." I read she started it impromptu while standing at the blackboard.
Driver sees a remarkably wise-looking kindly old gentleman standing just across the tracks, and stops to ask, "Did you see that train almost hit me?" And the gentleman replies, "It did."
In quantum mechanics the physical system is described through a wave function whose evolution over time is determined by the Schrodinger equation. The wave function represents infinite different possible results for the physical quantities related to the system, but when we take a measurement, only one of these infinite possibilities becomes real; after the measurement, we must therefore modify the wave function “by hand” to eliminate all other possible results, and this modification is called the “collapse” of the wave function. The fundamental problem with quantum mechanics is that interactions among particles are already included in the Schrodinger equation and such equation does not predict any collapse. The collapse of the wave function is a violation of the Schrodinger equation, i.e. a violation of the most fundamental laws of physics and therefore the cause of the collapse cannot be determined by the same laws of physics, in particular, it cannot be determined by the interactions already included in the Schrodinger equation. The Schrodinger equation is what allows us to make quantitative predictions about the outcomes of future measurements; everytime we make a measurement, we receive new information about the system, and we need to "update" our wave function, i.e. to collapse it, otherwise the Schrodinger equation would provides wrong predictions relative to successive measurements. After one century of debates, the problem of measurement in quantum mechanics is still open and still represents the crucial problem for all interpretations of quantum mechanics. In fact, on the one hand it represents a violation of the Schrodinger equation, that is, a violation of the fundamental laws of physics. On the other hand, it is necessary for the laws of quantum physics to make sense, and to be applied in the interpretation and prediction of the phenomena we observe. This is the inescapable contradiction against which, all attempts to reconcile quantum physics with realism, break. Quantum mechanics is incompatible with realism (that's why Einstein never accepted quantum mechanics); all alleged attempts to reconcile quantum mechanics with realism are flawed. Quantum mechanics implies that physical reality (the universe) consists of the collection of all observed phenomena and such phenomena do not exist independently of consciousness. In fact, the properties of a physical system are determined only after the collapse of the wave function; when the properties of the system are not yet determined, the system is not real, but only an idea, a hypothesis. Only when collapse occurs do properties become real because they take on a definite value. It makes no sense to assume that the system exists but its properties are indeterminate, because properties are an intrinsic aspect of the system itself. The collapse represents the transition from a hypothetical system to an actual system. The collapse of the wave function represents a non-physical event, since it violates the fundamental laws of physics, and can be associated with the only non-physical event we know of, consciousness. Therefore, the only consistent rational explanation of the collapse is that it occurs because consciousness is involved in the process. However, the fact that properties are created when a conscious mind observes the system in no way implies that it is the observer or his mind that creates those properties and causes the collapse; I regard this hypothesis as totally unreasonable (by the way, the universe is supposed to have existed even before the existence of humans). The point is that there must be a correlation between the collapse of the wave function (=violation of the physical laws) and the interaction with a non-physical agent (the human mind); however, correlation does not mean causation because the concomitance of two events does not imply a causal link. The consciousness that causes the collapse of the wave function must be an eternal consciousness, that is, a conscious God. This is the idealistic perspective, which implies that physical reality exists as a concept in the mind of God who directly creates the phenomena we observe, according to the matematical models through which He conceived the universe (the laws of physics); the collapse of the wave function is a representation of the moment when God creates the observed phenomenon. This is essentially the view of the Irish philosopher George Berkeley, and in this view God is not only the Creator, but also the Sustainer of the universe. Idealism provides the only logically consistent interpretation of quantum mechanics, but most physicists do not accept idealism because it contradicts their personal beliefs, so they prefer an objectively wrong interpretation that gives them the illusion that quantum mechanics is compatible with realism.
@@MrFreeze420 With the word consciousness I do not refer to self-awareness, but to the property of being conscious= having a mental experience such as sensations, emotions, thoughts, memories and even dreams. The most fundamental empirical piece of information we have is the existence of our mental experiences. Consciousness is what we experience, therefore we know exactly what consciousness is. Consciousness is what we know best because it is the only reality we directly know exactly as it is in itself, the only reality we directly experience because it is experience itself. We have then a direct empirical knowledge of consciousness and consciousness represents the necessary preliminary condition for all other knowledge, consciousness is the foundation of all knowledge.
The fact that I’m only your fifth like on this comment is astounding. What I just read is an outstanding deduction of quantum mechanics in-concert with God’s raw ability to create. As we continue to quantify everything, we observe mass compositions of wave functions on as microscopic of a level as humanly possible. Thus, we are able to study smaller and smaller forms of “invisible” matter on an individual level. Yet we continue to discover a seemingly endless loop of wave functions leaving physicists surprised that they don’t have an answer about the collapse of the wave function… there must be, in essence, a nondenominational conscious variable that is responsible for the start and collapse of all wave functions, and the way it occurs is as mathematical, if not more, as we humans have observed by the year 2024. I’m honestly not sure if that’s a sensible remark or not; I’m not a physicist by any means and have no intent to dismiss their expertise. I just think it’s becoming more apparent that the end of all wave functions, is literally God. To see a physical incarnation of God is something I have no explanation for, but hey, that just speaks to the fact that humans are limited to physically experiencing one constant set of wave functions while being completely able to theorize, observe, and study the other planes of existence we affect and are also a result of, usually via dreams and mechanical thought processes that predict the future wave functions and the precise magnitude at which we experience them based on other variables
That black board looks like they discovered eternal quantumessence of sprit|mind|body|soul. Or that could be called the quadessence of sprit|mind|body|soul. Or am I just trying to sound smart? Lol. Seriously, yes... I like listening to him also. Humble and sane.
What is wave function? Perhaps thinking E=mc2, Pilot, and Entropy (thermal dynamics)will confirm needed things for evolved perspective to lead to the facts. Every thing is conserved and recycled depending on the levels of radiation vs matter (regardless of scale). Consider entropy at a scale of the whole universe. Pilot makes most sense to me. But I am dumb and suffer dunning kruger effect now and then. Who knows? Not I. Lol
I'm currently studying physics as a grad student, so I should probably not be typing this and get back to work, but I want to humbly say that I don't think this video does quantum mechanics justice. First of all, I think saying the particle is in "many places" before being measured is problematic. The particle is not in many places, and it is not somewhere but we just don't know where. It is in a superposition represented by the wave function. This concept simply does not have any classical analog. It's a new thing that must be taken on its own terms. Much more importantly, it is not even the wave-function alone that makes quantum mechanics a weird and rich subject. Think about the dice example Don brought up. If they are "quantum" dice, then you can never predict what side they'll land on and all you can say is that each side shows up 1/6 of the time (fair dice). If they are normal - "classical" - dice, then you *can* know with certainty what side they'll land if you study how you throw them closely enough, but it is still the case that the dice fall on each side with frequency 1/6 over many rolls. Now tell me, what is the difference between these two scenarios? At the level of dice rolling, nothing really. Both sets of dice roll with 1/6 probability per side. If this were all there was to quantum mechanics, quantum mechanics would just be a very pompous way of saying that no matter how careful experimenters are, they can never predict anything with certainty, even in principle. The heart of quantum mechanics is *not* probability, but *interference*. Let me explain. Quantum mechanics says that for each way an event can happen, there is a special number called an *amplitude*. The amplitude is represented by something called a complex number. Don't mind what that is if you don't already know. What's important is that, unlike probabilities, which are always positive, complex numbers can cancel each other out when added together. To get the probability of the event happening, you add the amplitudes for each way the event could happen and then square the result. Because of this property, you can have situations where there is more than one way for an event to happen, but one way contributes a positive amplitude and the other a negative amplitude, so the amplitudes cancel out and the event never happens! This is exactly what's going on in the famed double slit experiment. With each slit open individually, you can find a particle at a specific location on the screen, but with both slits open, you never find the particle there (the dark bands). You've increased the number of ways the particle can get to the location, but instead of the particle getting there twice as often say, it never gets there. This canceling of amplitudes is interference, and it is essential to any discussion of what quantum mechanics really is all about.
Ok, but if the recorder or observing device is put at the two open slits the system acts like particles are being fired at the slits, with two distinct bands not an interference pattern resulting on the recording screen in front? Perhaps the interference or interaction has happened now at the slits, the interaction between matter and energy occurred, the result being the particle(s) came from out of everywhere into focus? I like the idea of thinking the electron was the size of the universe before it came into focus at the slits when recorded/observed.
Don is not making this video for you. (Grad student) He's making it to help people learning this stuff on youtube who have an interest in physics. You watch one video, you're confused. You watch 10 you start to sort of get it. Eventually stuff clicks. This is a 10 minute video to help novice phycisists understand more. Hopefully we'll learn something.
@@TK0_23_ That's a fair point. Perhaps I'm being too critical. Frankly, I'm very happy to see so many people on the internet who are interested in learning this stuff who don't come from a physics background like myself. I don't think this video is that bad though; it just leaves out some of the most important parts of QM and promotes some unhelpful thinking about what the wave function "means". It just falls short of imparting real understanding, imo, but I really do care about imparting that understanding to lay audiences. I'd like to address your point about watching videos and being confused because I think it gets to the heart of what I'm personally advocating for. Firstly, everyone should know that there are a lot of misconceptions out there, and many of them stem from trying to reduce quantum mechanics to classical concepts that people are familiar with. Really, what makes quantum mechanics so weird is that it can't be understood in terms of stuff you already know, so analogies tend to obscure rather than elucidate. What I think this means is that, counterintuitively, the easiest way to understand QM is to take it more literally and seriously without any analogies as a crutch. This involves forgetting all of your assumptions about how the world works or ought to work, which is no small task. There's a quote from Feynman about the wave-particle duality of electrons: "If I say they (electrons) behave like particles I give the wrong impression; also if I say they behave like waves. They behave in their own inimitable way." Here are a few videos that I think do QM justice but that are intended for lay audiences. The first one addresses alot of the misconceptions I alluded to explicitly, and spends a lot of time discussing how to think about the wave function, entanglement, and why small things and big things seem to behave differently. The second is from Feynman, and highlights the central role of interference. th-cam.com/video/q7v5NtV8v6I/w-d-xo.html th-cam.com/video/WWNnIWTVcMQ/w-d-xo.html
Minor nit pick: visualizing the square of the wave function - it's wrong. Square of a (sine) wave is continuous and differentiable. It doesn't have much bearing on the rest of the content presented.
Certainly true. But keep in mind how one would do the morphing of the sine to sine squared, from a mechanical point of view. And, of course, as bvbk007 notes, it isn't particularly fatal vis a vis the core points.
A sine-wave has positive-going segments and negative-going segments. When you square the negative-going segments, you are multiplying a negative number by a negative number. Basic arithmetic 101: the product of two (or, indeed any even number of) negative numbers is POSITIVE! So the waveform of the sine-squared will have ALL positive-going segments. This, by definition, will give a function that is neither continuous (since there is a corner point to deal with) nor differentiable (since there is a corner point to deal with).
@@DavidAndrewsPEC That's not true. Plot out a sin^2(x) function in excel. You'll see that it's smooth, continuous and differentiable. The picture in the video is |sin(x)|, which doesn't have those properties. Take the derivative of sin^2(x) and see if that function is ever discontinuous.
@@DavidAndrewsPEC First of all, a corner point is still continuous. Second of all, you don't get a corner when squaring a smooth curve passing through zero because the square function has a derivative of zero at zero and this will "flatten out" the corner into a locally parabolic shape just touching the x-axis.
You really explain this in an easy to understand kind of way, I’ve been interested in quantum mechanics for a while now and I couldn’t find a way to start learning about it, thanks for this video!
Don Lincoln is one of the *very* few in TH-cam who has both the required knowledge of the complex physics subject at hand and the skill&patience to teach it to us "less physics savvy".. at least to the level that we can use it to further build our understanding about that very subject
I don’t understand. Why do we have to think of the particle being everywhere that’s possibly allowed by the wave function at once? It’s just a probability distribution isn’t it? Once it’s detected, of course it’s only going to be in one place. Why can’t we think of it just as any other probability distribution, in which there’s multiple, possible states, some more probable than others, given the specific environmental conditions? How does thinking that the particle is in all those states at once, before detecting it, help us?
And that's _exactly_ what I was talking 'bout in my comment: Don made the WF sound like an 'object' - i.e., he implicitly introduced a bias for an _ontic_ standpoint - from which all the weirdness in QM is (hehe) born
Well, actually, we don’t know the reason why the wave function collapses in the first place, or even the exact moment it happens. That being said, the definition of measurement in quantum mechanics (QM) is the collapse of the wave function, but we don’t know why it collapses. It’s not simply the interaction between the particle and the measurement, as experiments like the delayed-choice quantum eraser allow particles to interact with the detector without collapsing. This is called the measurement problem, and there are several interpretations or hypotheses for it as well.
About what I thought as well: what was proved was that the Q.M. probabilistic equations are always correct in all tests, and all the others theories like "in both states at the same time/superposition" have no solid proof yet (like many tv and youtube documentaries would have you believe). Thanks Dr. Lincoln for clarifying this.
we don't need to understand it fundamentally to use it effectively said every engineer ever in the face of quantum mechanics scientists morph into engineers
The issue is, that all "interpretations" lead to the same maths, which never fails. Yes, that's not completely true (Bell's theorem), but despite Aspect's experiment, doesn't this mean a lot either (except if one insists on the universe being local and that entanglement does not existing). So in the end; the maths is all we have and every "explanation" is at the current state of understanding just irrelevant story telling. Unfortunately, I don't think this is going to change in the next few decades.
@@frankschneider6156 tis the same with engineers, all the different methods to solve a problem lead to one solution: the machine working for scientists the "machine" is Math
@@fuseteam You are pretty wrong. Math is just a (quite helpful) tool, but it's in the end nothing but a strongly formalized description of a mental model, based upon observations, that supports the deduction of conclusions and allows quantification and predictions. Highly useful of course, but the true "machine" as you call it, is the experiment. No experiment -> no science.There is lots of math in the literature that turned out to be simply that: irrelevant maths, that has got nothing to do with (observable) reality. Mathematics is not a natural science. And just because you were able to derive an equitation that tells how nature behaves, doesn't mean, that it really does.
@@frankschneider6156 math is the machine they use it to make prediction for which they perform experiments Experiments verifies that what the machine spews out is not nonsense Or conversely proves it's just nonsense Ofc you can perform experiments without using the machine akin to building a car, doable but it'll take more time Tldr; machines are build by man to explore the laws natural world _more or less_
"what is the wave function?" is the wrong question. We use vectors to describe classical mechanics, but we don't expect a real arrow to be there in front of everything that's moving, we know it's a mathematical object and we can use it to find information about our system (e.g. we can calculate the magnitude to find the velocity of the object). Similarly, the wave function is a (weird) mathematical object we can use (e.g. squaring it to find the particle position's) and I don't see why we should expect something actually waving. The correct question is "why is the quantum world described so nicely by a mathematical object that's so "unusual"?" My two cents.
It's really not that mysterious, but the details are buried in the uniquely exotic nature of differential geometry on 4-manifolds. Essentially, there will always be some fundamental ambiguity as to what the "true" microstate of any physical system on a 3+1 dimensional background manifold is, because there is an uncountably infinite continuum of "exotic" structures possible for the tangent space at every point on the manifold. Exotic R4's all have the same topological structure, so they are all homeomorphic to a solid 4-ball just like the "regular" R4, but aren't necessarily diffeomorphic - i.e. their differential structures are different.
Finally, a video that tells it like it is. This is the best video I have ever seen about quantum mechanics. It is simple, straightforward, and addresses some of the ridiculous ideas that have sprung up around quantum mechanics. I would also like to add that the Schrodinger's Cat argument was put forward as criticism, and was not meant as a serious example of the the true nature of the universe. The idea of the cat being simultaneously alive and dead, was derisive and meant to show the fallacious conclusions that can be drawn from quantum mechanics. Unfortunately that aspect of the argument has been lost and people cite the argument as serious theory.
Can you please tell us something about the "role of the observer in collapsing the wave function"? I guess it would help to put to rest some of the more weird ideas around quantum physics...I hope :)
Thank you for clarifying quantum theory to the point of simple intuitive reasoning even a layman can grasp. When attempting to follow and investigate the subject, the multitude of examples given in science media and documentaries often confuses more than explaining with all the bizarre thought experiments/paradoxes.
Thank you for the excellent video. One question I have is... If a particle, prior to being measured, exists in all possible locations of the wave function, then why are some of the locations more probable for it to be found in than others? Thank you.
So if knowing the wave form of a particle shows us that for an instant that particle is everywhere at once then the observer collapses the wave form via observation doesn't that simply say/show that the observer determines his own reality? If so doesn't that negate your previous statement when you said this was a wrong interpretation of quantum mechanics?
We have a really good grasp on how cars move. We know sedans are lighter and have better fuel mileage, trucks are stronger for hauling things, etc and we also have a great ability to calculate things like potential speed, acceleration, gas mileage, etc. We have entirely no idea what the inside of a car is, not the driving area or any clue of what an engine even looks like. We don't even know if they're gas or electric.
When there is the “collapse” of the wave function upon “observation” isn’t it really just creation of a new wave function since there can be no observation without an interaction. The resulting quantum object doesn’t just freeze at a point, it only has a definite location at the point of interactiin at which point the new combined particle continues with the new wave function. The wave function never “ stops” it just changes.
8:50: “...Nothing is real until it’s observed. Those things really aren’t connected to quantum mechanics at all.” As they say, science advances one funeral at a time...
Yes. What time is it? Now. When tomorrow at 8AM comes, what time will it be? Now. When 12/12/2025 noon comes, what time will it be? Now. So, is it ever NOT now? Isn’t Now the only time we will ever experience?
No. It can never be now. The speed of light still must meet our eyeballs, excite our vision rods, then be converted to electrical energy ad it traverses all the wiring to the visual cortex where the brains...of both scholar and idiot must evaluate the prediction of vision as submitted...and justify the perception created. All this takes time. And, by the time this completed, whatever we see is no longer as we see. There is never a now...at least for humans as we can only imagine now and that, too, takes time. We actually live in the past.
@@happyfase to perceive the present we must acknowledge the previous. Else we would no concept of present. And be as such would require there to exist no memory...or identity as we would not recall one moment from another.
Thank you Dr. Lincoln for this video. Glad to hear you’re forging into QM. Could you please do a video about the delayed-choice quantum eraser experiment?
@Star Trek Theory Please, at least obtain a basic understanding before commenting. @MegaOmea, LongLost summed it up nicely, pretty much anything that can be entangled with the particle (according to MWI). One thing is for sure, a conscious entity is not a requirement.
@Star Trek Theory You are an absolute fool, QM is the basis of a huge amount of technology used today, from lasers to transistors and semiconductors. And yes, the GPS is obviously dependant on QM & General relativity. Putting aside your weak attempts at trolling others, what is your profession? Have you left school yet? I have to keep reminding myself that mankind is not regressing, the issue is fools like you self educating online.. Am all for people questioning everything, but don't be an ignorant twat, you won't get far in life..
The biggest mystery of quantum mechanics is, why do we need it in the first place? Why don't we just keep arguing how many angels can stand on a needle's pin? We haven't really sorted out that one, remember?
I'd like to know because this has bothered me since the first video. I hope we are in one of the universes where they do get the cake and it's not just a lie.
Leonard Susskind was being interviewed regarding quantum physics basics and the interviewer stated “Ah, now I understand”. Susskind quite angrily replied “No you don’t. Nobody does”. The interviewer was visibly taken aback and stumbled into the next question. These videos are excellent, please keep them coming.
I tried to measure the position of the video on my computer, but it affected the outcome. I ended up in a weird nightmarish alternative universe where Donald Trump was US President and Boris Johnson Prime Minister of Great Britain .....
The fact that part of the explanation currently invokes statements like "it is what it is" excites me to no end! Thank u for the expertise- I'll keep saying 'it is what it is' to explain things that I don't fully understand but can accept and promise not to use it as an excuse to stop studying and learning!
I feel like the “shut up and calculate” school of thought makes the most sense. The problem that arises is when people mistake it for an ignoring of the problem instead of a flat rejection of the value of human macro-scale intuition and valuation. If your intuition is wrong, build yourself a new one out of facts.
The population of the Earth in 1900 was around 1.6 billion people, yet, there were tons of geniuses before and after the decades of 1900. Just to name a few, James Clerk Maxwell, Albert Einstein, Nikola Tesla, J. J Thompson, Neils Bohr, Erwin Schrodinger, Werner Heisenberg, Richard Feynman, Louis de Broglie, Ernest Rutherford, Max Planck, Paul Dirac, Max Born, Wolfgang Pauli, etc...The list can go on for a while. Today, in 21st century, there are more than 7 billion people on this planet. Yet, we have not seen the likes of the geniuses listed above. It's mind blowing, one would think that with more people, there is a higher probability of some super genius being born and changing the world like the Physicists and Scientists did around the 20th century. Yet, for the last 80 or so years, most of our understanding of Physics hasn't changed much, we have better tools to carry out close to accurate experiments, but we are still asking the same questions Quantum Physicists asked 100 years ago. It's just crazy that we are still very far from getting to the theory of everything.
Correct. But... he said the wave function is a mathematical function that describes what is going on. It is "like" a sine wave. Not it "is" a sine wave. It can take on other forms. His graph is to illustrate a point, not give an exact example of a sine wave, since it's not a sine wave.
haha "shut up and calculate" train of thought". Like it. Another great video from Don. Would love to see a future video that examines the differing interpretation more deeply, though I suspect that would be a loooong video
Parakmi I we are not idiots or geniuses. We just are. Education can be a stumbling block and we get into wrong paradigms for centuries all because we choose to believe and TEACH OTHERS things that are wrong. Atheist miss out on so much like this gem. “These three remain Faith Hope and Love” Faith in Past Hope for Future Love for Life Those three are the Singularity. Because only NOW exists .. the past is over ...the futures not here.... Only now exists.. and physicists need to pay more attention to those virtual partials. The matter antimatter thoughts that recognize those QF’s and past particle and future wave to be expected from it. The Photon lighting the way before it fades into dark matter particles after coming from dark energy waves.. nobody will read this but ... that’s life
Greatest thing about my job (High school custodian) is having the time to study physics, mathematics and philosophy so conveniently. Doing menial labor requires so little thought once the muscle memory develops which makes it the perfect time to listen to lectures and logging what I learned in a personal journal. I’m going to school part time majoring in Computer Science as well to maintain a healthy dose of academic rigor to keep me honest. (And I also don’t wanna be a janitor forever)
Thank you for choosing "wave function" as a subject and clearing the myhts created aroud that. Your way of telling things with sound palpable approach is very much appreciated.
I appreciate Don's honesty about these things. It's one of the main reasons I keep coming back to there videos. To clear up the woo woo. I wish all physicists would be 100% clear about what physics does and doesn't know. Same with astronomy.
Great video as always. It got me thinking that I'd be really interested to see a Dr. Lincoln video on Quantum Bayesianism , the school of thought that the wave functions should be interpreted as subjective Bayesian probabilities which reflect the observer's confidence of a particle's value versus being an objective measure with an actual physical counterpart. I don't know that I've seen any good videos about Quantum Bayesianism yet but it is one of the (as far as I know) possible interpretations of what Quantum Mechanics actually "is".
for smart ones, classical give all answers. according to science Logic and scientific method for achievement of knowledge quantum mechanics is nonsense :)))
@Emmett Brown my respect for Emmett Brown :) rules/laws of Universe are the same at all level of organization of matter. anything can be explained by "normal-classical" physics, without relativistic and quantum fantasies /unreal models/
I always believed (very small) matter behaves like energy as long as there is no interaction by another energy source or matter. Once disturbed by any other interaction energy (quantum) waves “materialises” into a distinct location. Similar as a lightening bolt that appears at a distinct location out from a diffuse electric field.
@@whocareswho If you are a nobody, the implication is that there are other nobodies. If there are an infinite number of nobodies at least one does understand it ;0)
Prof. Don , thanks for the "shoutout", i promise i will move forwards and solve this as soon as ive found homes for all the kittens left over from my last experiment (putting multiple cats into big boxes together . . . None were both dead and alive at the same time but curiously over time i did end up with more live animals than i started with) Wow !
Why does a quantum wave have more energy at some locations and less at others in the pattern of a wave? An explanation for the regularity and continuity of energy increases and decreases in pattern of wave would be great.
I have a complaint about the way many-worlds is presented: It's not that universes are created whenever a measurement occurs, it's that the wavefunction evolves according to the Schroedinger equation, but when we measure it, we become entangled with it, and each eigenstate of the measurement won't affect each other, which makes it act like another "world".
I subscribe to the "Occam's razor" view of complex problems. A pilot wave is so much simpler to visualize and understand than the many worlds theory - and it derives the same prediction without the clutter of infinite worlds.
In both the pilot wave theory and many worlds interpretation, it's pretty straightforward. It's just that the average person does not have a grasp of the idea of distributions and function spaces, which is what qm is all about, which seem complicated at first but turn out to be simple in practice. People say it's weird because it involves math and serious thinking, and when some people turn out incapable of doing so, they end just resenting it in a "the grapes are sour" kind of thinking. I've seen some people dismiss machine learning as "impractical" just because their brains can't handle the relatively simple math involved in it. Same story here.
Don, I'm not a physicist and I enjoy your videos very much. I don't fully understand them, but each viewing makes me incrementally more intimate with our universe, and that is appreciated. Locating the exact position of an electron is interesting, but I don't know why this is important. Seems to me that knowing an electron is either, bound to a nucleus or free and available, would tell you everything you need to know. How does knowing precisely where an electron is located help us explain/understand our world?
The "observer" is the unfortunate individual trying to make sense of the phenomenon he or she is observing, without realizing that the wave function doesn't "collapse"; it is always there. The wave function is merely the sum total of all possible interaction paths and modes that an interaction can take place over, giving a probability for each possible path. Which depends on the particular physical arrangement or environment setting the stage for the interactions to take place within. So, it is no surprise that when interactions take place in reality, they conform to that wave function. The essential piece missing from this puzzle is that, there is only ever one full spin boson exchanged between two half spin fermions. The all too common picture of a "photon", for example, being some sort of "packet of waves" scooting across space at light speed is misleading. That's not what a boson is. Fermions interact via bosons transtemporally and it always takes an emitter and an absorber. That point is not trivial, nor is the realization that a wave function doesn't just apply to one particular interaction. It applies to all of them, whether they actually happen or not.
An "observer" is a weird postulate from the Kopenhagen interpretation made up by Bohr (who also made up the event he called "wave function collapse") and is pretty outdated. Substitute observer with "interaction" to get a more modern view. When you now think about quantum fluctuations, resulting in virtual particles that interact with any object in superposition, you understand, why larger objects "collapse" way faster than smaller ones. The issue with QM: the maths works ... always, without exception, but nobody understands why. Explanations like Kopenhagen, multiple worlds or hidden variables are just stories made up, trying to explain it, but the truth is: nobody knows what's going on, so all interpretions are pretty much irrelevant. The only thing that exists is the maths.
What I understood. Presently, Quantum physics is far more complete w.r.t. theory and computation than what actually goes in reality (i.e. that comes by direct / indirect observation) at Quantum scale (
to visualize what happens at the quantum level, is important to understand that when a particle moves creates wave it self, because of the interaction of the quantum field with the particle but still be a particule and where the the wave is stronger is where probably the particucle is at,
I'd like to see an in-depth explanation of what 'detection' means. There has to be a better word to describe what happens. Detection implies a conscious being observing the wave function collapsing - but the Universe surely exists in areas where we aren't actively observing.
![[UNCUT]"ตุลามรณะ"ย้อนฟังคำทำนาย หมอดูทุกสาย ดวงเมืองร้อน (หมอปลาย ฟองสนาน อ.โอเล่)I คนดังนั่งเคลียร์](http://i.ytimg.com/vi/lE5az5VvT9M/mqdefault.jpg)
I like the way how Prof.Don Lincoln explains Physics in a very simple, yet precise and concise manner
@D.O.A. yuh.... absolutely
Your statement seems off. It would make sense if you said it was difficult and yet concise and precise. Saying he explained physics easily and yet it was concise and precise is extremely wrong. It makes no sense to add the yet.
@@Christopher._M but he says he's a physicist, not an English Major
@@tanmoydutta5846 the one that said it wasn't the physicist it was the person who commented.
@@Christopher._M relax bro, I'm just quoting one of Don Lincoln's sayings itself...from of his earlier videos.. 😂😂😂😂
I’ve seen so many videos over this topic over the years, and honestly this is the best 10 minute overview of QM I’ve ever seen.
I agree 👍
@@jonathaneves Me, too. 👍
Dr Don, you are the type of son my parents always wanted
But they got you instead. lol
/r/suicidebywords 😂
Go get a life kenneth kogut.
"Each idea has burrowed its way into the subconscious of people who are interested in science, but aren't quantum experts." - I love that wording, for some reason....
This is why quantum mechanics will never tell me how much they're going to charge to work on my photon-powered car until they actually do the work.
@GUS GREENBARM what?
Dr. Lincoln does an outstanding job of breaking down some of the nebulous aspects of Quantum Mechanics without talking over his audience or interjecting silly metaphors. He even presents the various main theories on the collapse of the wave function probabilities without imposing his opinion on the discussion. A lot of grade 12 physics and first year university instructors could really use a refresher on how to introduce this subject matter. They could help students start to understand the concepts without scaring so many of them out of the field before they even really get started. Worth a look. Good for Fermilab for bringing science education out of the lab and classroom to the masses.
I HAVE NEVER HEARD such a simple explanation of quantum mechanics, thanks a lot
Quantum mechanics and thermodynamics was a class I took my first semester in college. I'm not sure if I have recovered from that trauma to this day!
Just try to take things one day at a time.
😂😂😂😂
Those are 3 semester classes at the minimum.
This is quite hard to believe as statictical mechanics and thermodunamics is standardly taught only after classical mechanics which is is at least one semester alone. Not mentioning that quantum mechanics is taught after classical mechanics and electromagnetism as a minimum which is 1 semester each as a minimum.
@@MyYTwatcher My statement is factual. I was a chemistry major and that was the course they put me in my first semester in college.
Fermilab and PBS Spacetime uploaded on the same say? Christmas had come early'
Hal shot first indeed
Two of the best channels on TH-cam.
Same say potato, same say potato... Think about it 🙃
They uploaded on the same hour actually
I would love to see a collab one day of those two. 🙂
I didn't realize at the time, and that was a long time ago that I guess I was sort of introduced to "quanta." Must have been in the 2nd or 3rd grade. It was a poem that went like this:
Little drops of water
Little grains of sand
Make the mighty ocean
And the pleasant land
Thus the little minutes
Humble though they be
Make the mighty ages
Of eternity.
That is amazing. Thanks for posting that. Its so simple yet so true
@@lukesrockhouse > The poet's name is Julia Carney. There are variations, but the one I remember in class (more than 50 years ago) was the above.
I’m going to print and frame this. On my honor. Amazing.
@@MichaelGonzales-by1eo > At the time I posted this a year ago, I couldn't remember the author's name; only the poem by rote. Second graders usually don't remember who wrote or composed anything. The author is Julia Abigail Carney, a Boston teacher. It was written in 1845 in Boston. The title is "Little Things." I read she started it impromptu while standing at the blackboard.
"I swear, that train 0:24 went right through a STOP sign, Officer!" - j q t -
Driver sees a remarkably wise-looking kindly old gentleman standing just across the tracks, and stops to ask,
"Did you see that train almost hit me?"
And the gentleman replies,
"It did."
In quantum mechanics the physical system is described through a wave function whose evolution over time is determined by the Schrodinger equation. The wave function represents infinite different possible results for the physical quantities related to the system, but when we take a measurement, only one of these infinite possibilities becomes real; after the measurement, we must therefore modify the wave function “by hand” to eliminate all other possible results, and this modification is called the “collapse” of the wave function.
The fundamental problem with quantum mechanics is that interactions among particles are already included in the Schrodinger equation and such equation does not predict any collapse. The collapse of the wave function is a violation of the Schrodinger equation, i.e. a violation of the most fundamental laws of physics and therefore the cause of the collapse cannot be determined by the same laws of physics, in particular, it cannot be determined by the interactions already included in the Schrodinger equation. The Schrodinger equation is what allows us to make quantitative predictions about the outcomes of future measurements; everytime we make a measurement, we receive new information about the system, and we need to "update" our wave function, i.e. to collapse it, otherwise the Schrodinger equation would provides wrong predictions relative to successive measurements. After one century of debates, the problem of measurement in quantum mechanics is still open and still represents the crucial problem for all interpretations of quantum mechanics. In fact, on the one hand it represents a violation of the Schrodinger equation, that is, a violation of the fundamental laws of physics. On the other hand, it is necessary for the laws of quantum physics to make sense, and to be applied in the interpretation and prediction of the phenomena we observe. This is the inescapable contradiction against which, all attempts to reconcile quantum physics with realism, break.
Quantum mechanics is incompatible with realism (that's why Einstein never accepted quantum mechanics); all alleged attempts to reconcile quantum mechanics with realism are flawed. Quantum mechanics implies that physical reality (the universe) consists of the collection of all observed phenomena and such phenomena do not exist independently of consciousness. In fact, the properties of a physical system are determined only after the collapse of the wave function; when the properties of the system are not yet determined, the system is not real, but only an idea, a hypothesis. Only when collapse occurs do properties become real because they take on a definite value. It makes no sense to assume that the system exists but its properties are indeterminate, because properties are an intrinsic aspect of the system itself. The collapse represents the transition from a hypothetical system to an actual system.
The collapse of the wave function represents a non-physical event, since it violates the fundamental laws of physics, and can be associated with the only non-physical event we know of, consciousness. Therefore, the only consistent rational explanation of the collapse is that it occurs because consciousness is involved in the process. However, the fact that properties are created when a conscious mind observes the system in no way implies that it is the observer or his mind that creates those properties and causes the collapse; I regard this hypothesis as totally unreasonable (by the way, the universe is supposed to have existed even before the existence of humans). The point is that there must be a correlation between the collapse of the wave function (=violation of the physical laws) and the interaction with a non-physical agent (the human mind); however, correlation does not mean causation because the concomitance of two events does not imply a causal link. The consciousness that causes the collapse of the wave function must be an eternal consciousness, that is, a conscious God. This is the idealistic perspective, which implies that physical reality exists as a concept in the mind of God who directly creates the phenomena we observe, according to the matematical models through which He conceived the universe (the laws of physics); the collapse of the wave function is a representation of the moment when God creates the observed phenomenon. This is essentially the view of the Irish philosopher George Berkeley, and in this view God is not only the Creator, but also the Sustainer of the universe. Idealism provides the only logically consistent interpretation of quantum mechanics, but most physicists do not accept idealism because it contradicts their personal beliefs, so they prefer an objectively wrong interpretation that gives them the illusion that quantum mechanics is compatible with realism.
@@MrFreeze420 With the word consciousness I do not refer to self-awareness, but to the property of being conscious= having a mental experience such as sensations, emotions, thoughts, memories and even dreams. The most fundamental empirical piece of information we have is the existence of our mental experiences. Consciousness is what we experience, therefore we know exactly what consciousness is. Consciousness is what we know best because it is the only reality we directly know exactly as it is in itself, the only reality we directly experience because it is experience itself. We have then a direct empirical knowledge of consciousness and consciousness represents the necessary preliminary condition for all other knowledge, consciousness is the foundation of all knowledge.
The fact that I’m only your fifth like on this comment is astounding. What I just read is an outstanding deduction of quantum mechanics in-concert with God’s raw ability to create. As we continue to quantify everything, we observe mass compositions of wave functions on as microscopic of a level as humanly possible. Thus, we are able to study smaller and smaller forms of “invisible” matter on an individual level. Yet we continue to discover a seemingly endless loop of wave functions leaving physicists surprised that they don’t have an answer about the collapse of the wave function… there must be, in essence, a nondenominational conscious variable that is responsible for the start and collapse of all wave functions, and the way it occurs is as mathematical, if not more, as we humans have observed by the year 2024.
I’m honestly not sure if that’s a sensible remark or not; I’m not a physicist by any means and have no intent to dismiss their expertise. I just think it’s becoming more apparent that the end of all wave functions, is literally God. To see a physical incarnation of God is something I have no explanation for, but hey, that just speaks to the fact that humans are limited to physically experiencing one constant set of wave functions while being completely able to theorize, observe, and study the other planes of existence we affect and are also a result of, usually via dreams and mechanical thought processes that predict the future wave functions and the precise magnitude at which we experience them based on other variables
Don is one of the few physicists who brings me back down to ... reality.
Thanks, Don!
That black board looks like they discovered eternal quantumessence of sprit|mind|body|soul. Or that could be called the quadessence of sprit|mind|body|soul.
Or am I just trying to sound smart?
Lol.
Seriously, yes... I like listening to him also. Humble and sane.
What is wave function?
Perhaps thinking E=mc2, Pilot, and Entropy (thermal dynamics)will confirm needed things for evolved perspective to lead to the facts.
Every thing is conserved and recycled depending on the levels of radiation vs matter (regardless of scale). Consider entropy at a scale of the whole universe.
Pilot makes most sense to me.
But I am dumb and suffer dunning kruger effect now and then.
Who knows?
Not I.
Lol
I'm currently studying physics as a grad student, so I should probably not be typing this and get back to work, but I want to humbly say that I don't think this video does quantum mechanics justice.
First of all, I think saying the particle is in "many places" before being measured is problematic. The particle is not in many places, and it is not somewhere but we just don't know where. It is in a superposition represented by the wave function. This concept simply does not have any classical analog. It's a new thing that must be taken on its own terms.
Much more importantly, it is not even the wave-function alone that makes quantum mechanics a weird and rich subject. Think about the dice example Don brought up. If they are "quantum" dice, then you can never predict what side they'll land on and all you can say is that each side shows up 1/6 of the time (fair dice). If they are normal - "classical" - dice, then you *can* know with certainty what side they'll land if you study how you throw them closely enough, but it is still the case that the dice fall on each side with frequency 1/6 over many rolls. Now tell me, what is the difference between these two scenarios? At the level of dice rolling, nothing really. Both sets of dice roll with 1/6 probability per side. If this were all there was to quantum mechanics, quantum mechanics would just be a very pompous way of saying that no matter how careful experimenters are, they can never predict anything with certainty, even in principle.
The heart of quantum mechanics is *not* probability, but *interference*. Let me explain. Quantum mechanics says that for each way an event can happen, there is a special number called an *amplitude*. The amplitude is represented by something called a complex number. Don't mind what that is if you don't already know. What's important is that, unlike probabilities, which are always positive, complex numbers can cancel each other out when added together. To get the probability of the event happening, you add the amplitudes for each way the event could happen and then square the result. Because of this property, you can have situations where there is more than one way for an event to happen, but one way contributes a positive amplitude and the other a negative amplitude, so the amplitudes cancel out and the event never happens! This is exactly what's going on in the famed double slit experiment. With each slit open individually, you can find a particle at a specific location on the screen, but with both slits open, you never find the particle there (the dark bands). You've increased the number of ways the particle can get to the location, but instead of the particle getting there twice as often say, it never gets there. This canceling of amplitudes is interference, and it is essential to any discussion of what quantum mechanics really is all about.
Ok, but if the recorder or observing device is put at the two open slits the system acts like particles are being fired at the slits, with two distinct bands not an interference pattern resulting on the recording screen in front? Perhaps the interference or interaction has happened now at the slits, the interaction between matter and energy occurred, the result being the particle(s) came from out of everywhere into focus? I like the idea of thinking the electron was the size of the universe before it came into focus at the slits when recorded/observed.
Don is not making this video for you. (Grad student) He's making it to help people learning this stuff on youtube who have an interest in physics. You watch one video, you're confused. You watch 10 you start to sort of get it. Eventually stuff clicks. This is a 10 minute video to help novice phycisists understand more. Hopefully we'll learn something.
@@TK0_23_ That's a fair point. Perhaps I'm being too critical. Frankly, I'm very happy to see so many people on the internet who are interested in learning this stuff who don't come from a physics background like myself. I don't think this video is that bad though; it just leaves out some of the most important parts of QM and promotes some unhelpful thinking about what the wave function "means". It just falls short of imparting real understanding, imo, but I really do care about imparting that understanding to lay audiences.
I'd like to address your point about watching videos and being confused because I think it gets to the heart of what I'm personally advocating for. Firstly, everyone should know that there are a lot of misconceptions out there, and many of them stem from trying to reduce quantum mechanics to classical concepts that people are familiar with. Really, what makes quantum mechanics so weird is that it can't be understood in terms of stuff you already know, so analogies tend to obscure rather than elucidate. What I think this means is that, counterintuitively, the easiest way to understand QM is to take it more literally and seriously without any analogies as a crutch. This involves forgetting all of your assumptions about how the world works or ought to work, which is no small task. There's a quote from Feynman about the wave-particle duality of electrons: "If I say they (electrons) behave like particles I give the wrong impression; also if I say they behave like waves. They behave in their own inimitable way."
Here are a few videos that I think do QM justice but that are intended for lay audiences. The first one addresses alot of the misconceptions I alluded to explicitly, and spends a lot of time discussing how to think about the wave function, entanglement, and why small things and big things seem to behave differently. The second is from Feynman, and highlights the central role of interference.
th-cam.com/video/q7v5NtV8v6I/w-d-xo.html
th-cam.com/video/WWNnIWTVcMQ/w-d-xo.html
I always hated Schrodinger's cat story. Thanks Don to clarify and get rid all those false ideas of quantum world. Excellent video.
Minor nit pick: visualizing the square of the wave function - it's wrong. Square of a (sine) wave is continuous and differentiable. It doesn't have much bearing on the rest of the content presented.
he's showing something like the square of the absolute value of sin(x)
Certainly true. But keep in mind how one would do the morphing of the sine to sine squared, from a mechanical point of view. And, of course, as bvbk007 notes, it isn't particularly fatal vis a vis the core points.
A sine-wave has positive-going segments and negative-going segments. When you square the negative-going segments, you are multiplying a negative number by a negative number.
Basic arithmetic 101: the product of two (or, indeed any even number of) negative numbers is POSITIVE! So the waveform of the sine-squared will have ALL positive-going segments.
This, by definition, will give a function that is neither continuous (since there is a corner point to deal with) nor differentiable (since there is a corner point to deal with).
@@DavidAndrewsPEC That's not true. Plot out a sin^2(x) function in excel. You'll see that it's smooth, continuous and differentiable. The picture in the video is |sin(x)|, which doesn't have those properties.
Take the derivative of sin^2(x) and see if that function is ever discontinuous.
@@DavidAndrewsPEC First of all, a corner point is still continuous. Second of all, you don't get a corner when squaring a smooth curve passing through zero because the square function has a derivative of zero at zero and this will "flatten out" the corner into a locally parabolic shape just touching the x-axis.
You really explain this in an easy to understand kind of way, I’ve been interested in quantum mechanics for a while now and I couldn’t find a way to start learning about it, thanks for this video!
Noooo, do not kill Schrodinger's cat, let curiosity do that.
eh it's got nine lives ^^
Curiosity was sent to Mars specifically to exterminate cats
I was curious so I opened the box and the cat was dead :( My curiosity killed it! ;'{
Q: How many physicists does it take to kill a cat?
A: Just one, Schrödinger, but you may need several parallel versions of him.
@aDBo'Ch 1 ok have a good day
Don Lincoln is one of the *very* few in TH-cam who has both the required knowledge of the complex physics subject at hand and the skill&patience to teach it to us "less physics savvy".. at least to the level that we can use it to further build our understanding about that very subject
Easy to understand and unbelievably informative as always, greetings from Grreece.
Your wave function explanation was the most clear I have experienced Prof. Lincoln, thank you!
Many thanks to everyone who contributed to this channel. That must be the Fermilab difference. Thank you Professor Don Lincoln.
It has really been dumbed-down for us stupids.
I don’t understand. Why do we have to think of the particle being everywhere that’s possibly allowed by the wave function at once? It’s just a probability distribution isn’t it? Once it’s detected, of course it’s only going to be in one place. Why can’t we think of it just as any other probability distribution, in which there’s multiple, possible states, some more probable than others, given the specific environmental conditions? How does thinking that the particle is in all those states at once, before detecting it, help us?
And that's _exactly_ what I was talking 'bout in my comment: Don made the WF sound like an 'object' - i.e., he implicitly introduced a bias for an _ontic_ standpoint - from which all the weirdness in QM is (hehe) born
Well, actually, we don’t know the reason why the wave function collapses in the first place, or even the exact moment it happens. That being said, the definition of measurement in quantum mechanics (QM) is the collapse of the wave function, but we don’t know why it collapses. It’s not simply the interaction between the particle and the measurement, as experiments like the delayed-choice quantum eraser allow particles to interact with the detector without collapsing. This is called the measurement problem, and there are several interpretations or hypotheses for it as well.
About what I thought as well: what was proved was that the Q.M. probabilistic equations are always correct in all tests, and all the others theories like "in both states at the same time/superposition" have no solid proof yet (like many tv and youtube documentaries would have you believe). Thanks Dr. Lincoln for clarifying this.
Dr. Lincoln is the greatest! I've read and heard about the wave function and always wondered why I still didn't know what it is! Thank you!
we don't need to understand it fundamentally to use it effectively
said every engineer ever
in the face of quantum mechanics scientists morph into engineers
The issue is, that all "interpretations" lead to the same maths, which never fails. Yes, that's not completely true (Bell's theorem), but despite Aspect's experiment, doesn't this mean a lot either (except if one insists on the universe being local and that entanglement does not existing). So in the end; the maths is all we have and every "explanation" is at the current state of understanding just irrelevant story telling. Unfortunately, I don't think this is going to change in the next few decades.
@@frankschneider6156 tis the same with engineers, all the different methods to solve a problem lead to one solution: the machine working
for scientists the "machine" is Math
@@happyfase exactly :p
@@fuseteam
You are pretty wrong. Math is just a (quite helpful) tool, but it's in the end nothing but a strongly formalized description of a mental model, based upon observations, that supports the deduction of conclusions and allows quantification and predictions. Highly useful of course, but the true "machine" as you call it, is the experiment.
No experiment -> no science.There is lots of math in the literature that turned out to be simply that: irrelevant maths, that has got nothing to do with (observable) reality. Mathematics is not a natural science. And just because you were able to derive an equitation that tells how nature behaves, doesn't mean, that it really does.
@@frankschneider6156 math is the machine
they use it to make prediction for which they perform experiments
Experiments verifies that what the machine spews out is not nonsense
Or conversely proves it's just nonsense
Ofc you can perform experiments without using the machine akin to building a car, doable but it'll take more time
Tldr; machines are build by man to explore the laws natural world _more or less_
"what is the wave function?" is the wrong question. We use vectors to describe classical mechanics, but we don't expect a real arrow to be there in front of everything that's moving, we know it's a mathematical object and we can use it to find information about our system (e.g. we can calculate the magnitude to find the velocity of the object). Similarly, the wave function is a (weird) mathematical object we can use (e.g. squaring it to find the particle position's) and I don't see why we should expect something actually waving.
The correct question is "why is the quantum world described so nicely by a mathematical object that's so "unusual"?"
My two cents.
It's really not that mysterious, but the details are buried in the uniquely exotic nature of differential geometry on 4-manifolds. Essentially, there will always be some fundamental ambiguity as to what the "true" microstate of any physical system on a 3+1 dimensional background manifold is, because there is an uncountably infinite continuum of "exotic" structures possible for the tangent space at every point on the manifold. Exotic R4's all have the same topological structure, so they are all homeomorphic to a solid 4-ball just like the "regular" R4, but aren't necessarily diffeomorphic - i.e. their differential structures are different.
0:27 I can only imagine what was going on in the head of the driver when he saw the train "I'm already late for the theater I'll take my chances!"
Finally, a video that tells it like it is. This is the best video I have ever seen about quantum mechanics. It is simple, straightforward, and addresses some of the ridiculous ideas that have sprung up around quantum mechanics.
I would also like to add that the Schrodinger's Cat argument was put forward as criticism, and was not meant as a serious example of the the true nature of the universe. The idea of the cat being simultaneously alive and dead, was derisive and meant to show the fallacious conclusions that can be drawn from quantum mechanics. Unfortunately that aspect of the argument has been lost and people cite the argument as serious theory.
Can you please tell us something about the "role of the observer in collapsing the wave function"? I guess it would help to put to rest some of the more weird ideas around quantum physics...I hope :)
Thank you for clarifying quantum theory to the point of simple intuitive reasoning even a layman can grasp. When attempting to follow and investigate the subject, the multitude of examples given in science media and documentaries often confuses more than explaining with all the bizarre thought experiments/paradoxes.
Thank you for the excellent video. One question I have is... If a particle, prior to being measured, exists in all possible locations of the wave function, then why are some of the locations more probable for it to be found in than others? Thank you.
So if knowing the wave form of a particle shows us that for an instant that particle is everywhere at once then the observer collapses the wave form via observation doesn't that simply say/show that the observer determines his own reality? If so doesn't that negate your previous statement when you said this was a wrong interpretation of quantum mechanics?
And here I thought it related to the repair and maintenance of quanta.
Lmao mate
7:55 "Those are great words because... well... you know... philosophers!"
This guy is really funny :-)
It's like: we know how to drive the car, but we don't yet know how the engine works.
And what's worse: there is at least some chance, that we may never know.
I think we know how the engine works. (The calculate part)
We just don’t know what and engine is.
We have a really good grasp on how cars move. We know sedans are lighter and have better fuel mileage, trucks are stronger for hauling things, etc and we also have a great ability to calculate things like potential speed, acceleration, gas mileage, etc.
We have entirely no idea what the inside of a car is, not the driving area or any clue of what an engine even looks like. We don't even know if they're gas or electric.
One of the better videos I have seen from you guys. Keep up the good work. This was clear and concise.
"The crux of the biscuit is the Apostrophe."
Frank Zappa
Great conceptual continuity.
I told him no no no!
He told me yes yes yes!
I said I do it all time.
Aint this boogie a mess.
I finally bought a nice tv over the weekend, now I get to see Dr Lincoln’s mustache in all of its life size glory. It’s trying to tell me something.
It's telling you that you should grow your own.
@@drdon5205 I have tried and that is the reason my coworkers spent all of Movember calling me "salt and pepper".
This video is above my expectation _value_
The topics are explained so well in all the videos, glad to be a subscriber of this awesome channel
8:34 Sean Caroll for the win!
Lazy idea
When there is the “collapse” of the wave function upon “observation” isn’t it really just creation of a new wave function since there can be no observation without an interaction. The resulting quantum object doesn’t just freeze at a point, it only has a definite location at the point of interactiin at which point the new combined particle continues with the new wave function. The wave function never “ stops” it just changes.
Excellent video as usual 👍
I feel like giving you a big hug for this. Thank you sir.
8:50: “...Nothing is real until it’s observed. Those things really aren’t connected to quantum mechanics at all.”
As they say, science advances one funeral at a time...
Sometimes in most cases you can pretty much extrapolate the process
Nothing in time is real
Yes. What time is it? Now. When tomorrow at 8AM comes, what time will it be? Now. When 12/12/2025 noon comes, what time will it be? Now. So, is it ever NOT now? Isn’t Now the only time we will ever experience?
No. It can never be now.
The speed of light still must meet our eyeballs, excite our vision rods, then be converted to electrical energy ad it traverses all the wiring to the visual cortex where the brains...of both scholar and idiot must evaluate the prediction of vision as submitted...and justify the perception created.
All this takes time. And, by the time this completed, whatever we see is no longer as we see.
There is never a now...at least for humans as we can only imagine now and that, too, takes time.
We actually live in the past.
@@happyfase to perceive the present we must acknowledge the previous.
Else we would no concept of present. And be as such would require there to exist no memory...or identity as we would not recall one moment from another.
Thank you Dr. Lincoln for this video. Glad to hear you’re forging into QM.
Could you please do a video about the delayed-choice quantum eraser experiment?
But what counts as a detector that can collapse a particle's wave function?
Anything that can interact with it.
@Star Trek Theory Your name tells me you know nothing about quantum mechanics.
@Star Trek Theory Please, at least obtain a basic understanding before commenting. @MegaOmea, LongLost summed it up nicely, pretty much anything that can be entangled with the particle (according to MWI). One thing is for sure, a conscious entity is not a requirement.
@Star Trek Theory You are an absolute fool, QM is the basis of a huge amount of technology used today, from lasers to transistors and semiconductors. And yes, the GPS is obviously dependant on QM & General relativity. Putting aside your weak attempts at trolling others, what is your profession? Have you left school yet? I have to keep reminding myself that mankind is not regressing, the issue is fools like you self educating online.. Am all for people questioning everything, but don't be an ignorant twat, you won't get far in life..
The biggest mystery of quantum mechanics is, why do we need it in the first place? Why don't we just keep arguing how many angels can stand on a needle's pin? We haven't really sorted out that one, remember?
Really love this channel. It's gotten me really interested in physics!
Thanks, Dr Lincoln. I feel that I know something I didn't know before watching your video, but that usually the case after I watch a video of yours.
9:00 FOR THE ANSWER TO THE TITLE
Thank you Dr. Lincoln (and by inference - Femilab) … a great - concise - (and) - enjoyable discussion on this often misrepresented topic. 👍🏽👍🏽
I'm convinced that my cat is both a zombie and capable of generating reality.
Maybe the cat is not yours... Maybe it is Schrödingers cat...
HMMM. SOUNDS A LOT LIKE THE EX...
I am convinced my cat contacts his planet of origin every night requesting permission to take my life!
That could explain how cats get into and out of so many weirdly impossible/improbable places
Thanks Dr. Don for another informative video that maintained my interest in the topic. I look forward to the next.
did Uli get his goodbye cake?
willem schuurmans Only if they picked it up at 2:30 pm.
I'd like to know because this has bothered me since the first video. I hope we are in one of the universes where they do get the cake and it's not just a lie.
Depends on the universe in question. But Everett assured me, that he did get it (in 50%).
Leonard Susskind was being interviewed regarding quantum physics basics and the interviewer stated “Ah, now I understand”. Susskind quite angrily replied “No you don’t. Nobody does”. The interviewer was visibly taken aback and stumbled into the next question.
These videos are excellent, please keep them coming.
Yess my favorite proffesor is back ..🙌🤩👍
Wow such a good explanation Professor! Thanks so much!!
I tried to measure the position of the video on my computer, but it affected the outcome. I ended up in a weird nightmarish alternative universe where Donald Trump was US President and Boris Johnson Prime Minister of Great Britain .....
@MomoTheBellyDancer I know, right? Quantum physics gave me the munchies.
The fact that part of the explanation currently invokes statements like "it is what it is" excites me to no end! Thank u for the expertise- I'll keep saying 'it is what it is' to explain things that I don't fully understand but can accept and promise not to use it as an excuse to stop studying and learning!
I feel like the “shut up and calculate” school of thought makes the most sense. The problem that arises is when people mistake it for an ignoring of the problem instead of a flat rejection of the value of human macro-scale intuition and valuation. If your intuition is wrong, build yourself a new one out of facts.
The population of the Earth in 1900 was around 1.6 billion people, yet, there were tons of geniuses before and after the decades of 1900. Just to name a few, James Clerk Maxwell, Albert Einstein, Nikola Tesla, J. J Thompson, Neils Bohr, Erwin Schrodinger, Werner Heisenberg, Richard Feynman, Louis de Broglie, Ernest Rutherford, Max Planck, Paul Dirac, Max Born, Wolfgang Pauli, etc...The list can go on for a while.
Today, in 21st century, there are more than 7 billion people on this planet. Yet, we have not seen the likes of the geniuses listed above. It's mind blowing, one would think that with more people, there is a higher probability of some super genius being born and changing the world like the Physicists and Scientists did around the 20th century.
Yet, for the last 80 or so years, most of our understanding of Physics hasn't changed much, we have better tools to carry out close to accurate experiments, but we are still asking the same questions Quantum Physicists asked 100 years ago.
It's just crazy that we are still very far from getting to the theory of everything.
*_...square [_**_04:56_**_]-that's not square of sin(x)..._*
Correct. But... he said the wave function is a mathematical function that describes what is going on. It is "like" a sine wave. Not it "is" a sine wave. It can take on other forms. His graph is to illustrate a point, not give an exact example of a sine wave, since it's not a sine wave.
haha "shut up and calculate" train of thought". Like it.
Another great video from Don.
Would love to see a future video that examines the differing interpretation more deeply, though I suspect that would be a loooong video
9:30 "It's going to take a genius to move us forward."
No.
In this particular situation one complete idiot will suffice.
There are literally billions in existence today... some of them occupy high offices of power... and yet here we are. 🤷♂️
I totally agree, we are at the tipping point.
All idiots know the answer to everything.
The idiot will be designated as genius in that case.
Parakmi I we are not idiots or geniuses. We just are. Education can be a stumbling block and we get into wrong paradigms for centuries all because we choose to believe and TEACH OTHERS things that are wrong.
Atheist miss out on so much like this gem. “These three remain Faith Hope and Love”
Faith in Past
Hope for Future
Love for Life
Those three are the Singularity. Because only NOW exists .. the past is over ...the futures not here.... Only now exists.. and physicists need to pay more attention to those virtual partials. The matter antimatter thoughts that recognize those QF’s and past particle and future wave to be expected from it.
The Photon lighting the way before it fades into dark matter particles after coming from dark energy waves.. nobody will read this but ... that’s life
Greatest thing about my job (High school custodian) is having the time to study physics, mathematics and philosophy so conveniently. Doing menial labor requires so little thought once the muscle memory develops which makes it the perfect time to listen to lectures and logging what I learned in a personal journal. I’m going to school part time majoring in Computer Science as well to maintain a healthy dose of academic rigor to keep me honest. (And I also don’t wanna be a janitor forever)
Thank you for choosing "wave function" as a subject and clearing the myhts created aroud that. Your way of telling things with sound palpable approach is very much appreciated.
i got to here so fast that an electron had a defined position and momentum at the same time
looks like you broke reality than
no wonder microsoft is embracing open source
I appreciate Don's honesty about these things. It's one of the main reasons I keep coming back to there videos. To clear up the woo woo. I wish all physicists would be 100% clear about what physics does and doesn't know. Same with astronomy.
Now that you've given a surface level understanding can you melt our brains with "the delayed choice quantum eraser" ?
Scientists: It just be like that, bruh
The Science Asylum did a good video on that one! I re-watch it every so often
Great video as always. It got me thinking that I'd be really interested to see a Dr. Lincoln video on Quantum Bayesianism , the school of thought that the wave functions should be interpreted as subjective Bayesian probabilities which reflect the observer's confidence of a particle's value versus being an objective measure with an actual physical counterpart. I don't know that I've seen any good videos about Quantum Bayesianism yet but it is one of the (as far as I know) possible interpretations of what Quantum Mechanics actually "is".
To quantum or to classical, that's the question.
for smart ones, classical give all answers. according to science Logic and scientific method for achievement of knowledge quantum mechanics is nonsense :)))
@Emmett Brown two contradictory statements can't be both true - second law of science Logic :)
@Emmett Brown my respect for Emmett Brown :)
rules/laws of Universe are the same at all level of organization of matter. anything can be explained by "normal-classical" physics, without relativistic and quantum fantasies /unreal models/
I always believed (very small) matter behaves like energy as long as there is no interaction by another energy source or matter. Once disturbed by any other interaction energy (quantum) waves “materialises” into a distinct location. Similar as a lightening bolt that appears at a distinct location out from a diffuse electric field.
_I think I can safely say that nobody understands quantum mechanics._ -Richard Feynman, _The Character of Physical Law,_ 1965
💕 ☮ 🌎 🌌
Feynman was wrong. I'm a nobody and I don't understand quantum mechanics.
@@whocareswho If you are a nobody, the implication is that there are other nobodies. If there are an infinite number of nobodies at least one does understand it ;0)
@@whocareswho ha
The more you understand QM
the less you understand QM.
I like the thought that i have something in common with these theoretical physicists i dont understand quantum physics
Conveying information by someone who is not egotistical is a delight. Thank you
So a universe where the sun is a giant hotdog bun probably isn’t a thing in any version of reality... darn.
Hold on now, let's not jump to conclusions.
@@Soupy_loopy So hotdog-verse still has a chance. YES! As long as we believe, it exists somewhere.
Prof. Don , thanks for the "shoutout", i promise i will move forwards and solve this as soon as ive found homes for all the kittens left over from my last experiment (putting multiple cats into big boxes together . . . None were both dead and alive at the same time but curiously over time i did end up with more live animals than i started with) Wow !
Don Lincoln looks like a composite of Disney monsters
7:30 Thank you. I don't think I ever heard another physicist honest/clever enough to admit that, I always thought I was missing something out.
I’ve been in the “shut up and calculate” community since my first encounter with quantum mechanics.
Me too
Why does a quantum wave have more energy at some locations and less at others in the pattern of a wave? An explanation for the regularity and continuity of energy increases and decreases in pattern of wave would be great.
Isn't there a "t" in "quantum"?
Is quannum mechanics a thing?
Depends on your accent, same as "twenny".
@@LuisAldamiz tree fiddy
@@LuisAldamiz th-cam.com/video/X5Jp-j2PeO8/w-d-xo.html
@@lohphat - Not the same thing at all. Your link is about vowels, not consonant clusters. Also nt>nn is extremely common, at least in the USA.
Luis Aldamiz I CAN’T STANNEM.
I have a complaint about the way many-worlds is presented: It's not that universes are created whenever a measurement occurs, it's that the wavefunction evolves according to the Schroedinger equation, but when we measure it, we become entangled with it, and each eigenstate of the measurement won't affect each other, which makes it act like another "world".
I am literally afraid of my cat!
@Star Trek Theory my cat is a little feral and he has sharp claws. I mean he could take your eye out.
I subscribe to the "Occam's razor" view of complex problems. A pilot wave is so much simpler to visualize and understand than the many worlds theory - and it derives the same prediction without the clutter of infinite worlds.
Quantum mechanics is weird.
In both the pilot wave theory and many worlds interpretation, it's pretty straightforward. It's just that the average person does not have a grasp of the idea of distributions and function spaces, which is what qm is all about, which seem complicated at first but turn out to be simple in practice.
People say it's weird because it involves math and serious thinking, and when some people turn out incapable of doing so, they end just resenting it in a "the grapes are sour" kind of thinking. I've seen some people dismiss machine learning as "impractical" just because their brains can't handle the relatively simple math involved in it. Same story here.
Holy Fu*k he dissed all the philosophers in such a smooth way
Actually, I "hated" his comments about philosophers... A big disservice, I think.
@Contre Viole 32 Your justification is as confusing to me as Dr. Don's suggestion, in a quantum sort of manner, I mean.
8:45 that 3D brain animation is the most important thing I've ever witnessed. Absolutely life-changing.
Don, I'm not a physicist and I enjoy your videos very much. I don't fully understand them, but each viewing makes me incrementally more intimate with our universe, and that is appreciated. Locating the exact position of an electron is interesting, but I don't know why this is important. Seems to me that knowing an electron is either, bound to a nucleus or free and available, would tell you everything you need to know. How does knowing precisely where an electron is located help us explain/understand our world?
Please do a video discussing what an Observer is.
The "observer" is the unfortunate individual trying to make sense of the phenomenon he or she is observing, without realizing that the wave function doesn't "collapse"; it is always there. The wave function is merely the sum total of all possible interaction paths and modes that an interaction can take place over, giving a probability for each possible path. Which depends on the particular physical arrangement or environment setting the stage for the interactions to take place within. So, it is no surprise that when interactions take place in reality, they conform to that wave function. The essential piece missing from this puzzle is that, there is only ever one full spin boson exchanged between two half spin fermions. The all too common picture of a "photon", for example, being some sort of "packet of waves" scooting across space at light speed is misleading. That's not what a boson is. Fermions interact via bosons transtemporally and it always takes an emitter and an absorber. That point is not trivial, nor is the realization that a wave function doesn't just apply to one particular interaction. It applies to all of them, whether they actually happen or not.
An "observer" is a weird postulate from the Kopenhagen interpretation made up by Bohr (who also made up the event he called "wave function collapse") and is pretty outdated. Substitute observer with "interaction" to get a more modern view. When you now think about quantum fluctuations, resulting in virtual particles that interact with any object in superposition, you understand, why larger objects "collapse" way faster than smaller ones.
The issue with QM: the maths works ... always, without exception, but nobody understands why. Explanations like Kopenhagen, multiple worlds or hidden variables are just stories made up, trying to explain it, but the truth is: nobody knows what's going on, so all interpretions are pretty much irrelevant. The only thing that exists is the maths.
Thank you. It's crazy how many people have tried to explain the basics WITHOUT bringing up Maxwell Planck.
I like your raw honesty about how we still basically have no idea what is actually going on.
Is that what you got out of it? Nothing? :-)
me (at intro): ready to fight thanos
me (during video): gets panic attack
I just found out about you half an hour ago and I love your videos
brilliant short explanation of this complicated subject 👌
Personally i think it is more informative channel about physics that i have subscribed so far. Keep it Sir Don Lincoln..God bless you
What I understood.
Presently, Quantum physics is far more complete w.r.t. theory and computation than what actually goes in reality (i.e. that comes by direct / indirect observation) at Quantum scale (
to visualize what happens at the quantum level, is important to understand that when a particle moves creates wave it self, because of the interaction of the quantum field with the particle but still be a particule and where the the wave is stronger is where probably the particucle is at,
I'd like to see an in-depth explanation of what 'detection' means. There has to be a better word to describe what happens. Detection implies a conscious being observing the wave function collapsing - but the Universe surely exists in areas where we aren't actively observing.
An interaction between particles that always "know" when to exchange by "magic?" a virtual photon?