The Heisenberg Uncertainty Principle might not mean what you think it means: Hank clears things up for us in this edition of IDTIMWYTIM, by distinguishing between the Uncertainty Principle and the Observer Effect, which are often conflated.
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when i hear the word "impossible" i get really shocked that i cant understand "Heisenberg Uncertainty Principle"
because how can you know it's impossible even in the future..i don't really get why
i get that if you want to know the position more accurately you have to let go momentum ,because you would have to increase number of waves.
i still don't understand the relation between number of waves and the momentum as they are inversely proportional ,so as you increase number of waves you decrease momentum and get "less probability of position" ,so what makes the momentum have more probabilities .
i don't get how and why.. if anyone have a simple explanation for someone that have just got graduated from high school,please help :\
I thought the Heisenberg principle tells that if you increase the certainty of the probable location, the waveform kinda collapse, meaning it becomes kinda like 1/2 wave. That means you can't measure the wavelength because the wavelength thar exist isn't fair. Which has to do with observations, because the observer do something to increase probability to measure the position of said electron. The more you want to know about the exact position, the more scrapped the wavefunction. Now how does Heisenberg principle isn't related to observer effect when it is the observer himself that increase the probability of momentum?
A cop pulls over a physicist and asks, "do you know how fast you were going?"
The physicist replies, "no, but i can tell you exactly where we are."
The cop says, "you were going 75 miles per hour."
The physicist throws his hands in the air, and cries, "oh great, now we're lost."
So to be clear, we don’t know why the observer effect occurs? He said some physicists believe it’s the measuring that makes it act differently. Is this known to be the case or is it not yet perfectly understood?
But doesn't pilot wave theory hold that the uncertainty principle really is the observer effect (i.e. that it's actually impossible, in principle, to know both motion and position, in the same way that you could theoretically predict the outcome of a coin toss if you knew all variables involved)? I know this is a less popular interpretation of quantum physics, but, to my knowledge, it explains experimental results as well as other interpretations. I'm far from an expert, so if my understanding of pilot wave theory is wrong, please correct me.
We can imagine an electron as the moving blade of a motor fan(though it sounds insane but...). Even if we look closely, we cannot determine the exact position of the electron at any given instant. It will feel like we are watching the electron move over the whole space.
Five years later, have a look at Quantum Realism :)
In other words, just because we do not observe or measure something doesn't mean it isn't real or isn't so. My family doesn't pop in and out of existence as I do or don't measure or observe them and Hank doesn't cease to exist while I'm moving to the next video. Quantum Realism theorises that we can predict stuff about particles, we just suck at taking measurements of them right now. I'll definitely be keeping all this in mind when I do Quantum Physics at ANU (Canberra) in 2019 :)
What if sub atomic particals such as light photons are particals not waves but the particals move in wave patterns. explaining the slit experiment and why Heisenberg could not mathematiclly determine both speed and location. Liquids and gases can move in this way so light photons in theory quiet possibly could aswell.
im blind and deaf, and its impossible to locate someone without killing them.
i locate them by firing a pistol, and waiting for the vibrations from their bodys hitting the ground. i see nothing wrong with this
Researching quantum mechanics is a little bit like being a blind person who observes objects by throwing tennis balls at them and figuring out the trajectory they bounce back at, and also you're trying to watch a tennis game.
Ugh... scientists do not the "accept this duality without totally understanding it." We absolutely understand it. Electrons and photons are PARTICLES. They exist in discrete units of 1, 2, 3, etc. You can have one electron or one photon, but you cannot have 1.5 electrons or 3.7 photons. That is most definitely what a PARTICLE is like.
The wave aspect of particles is determined by the Schrodinger equation, which governs the BEHAVIOR of particles. The probability of finding a particle in some position with some velocity is entirely dictated by a WAVE equation. Duality can therefore be perfectly described in terms of particles whose behaviors are governed by wave equations.
Yes, there are many caveats to that and many variations of interpretation, but that is the fundamental explanation of duality.
I'm sorry, but your explanation of the Uncertainty Principle is completely wrong. There is no reason why you can't measure position and momentum simultaneously. The principle of uncertainty has to do with REPEATING the experiment over and over. If you devise an experiment that REPEATEDLY produces the same position within a very tight variance, then you will necessarily observe a very large variance on the momentum, and vice versa.
The word "uncertainty" is literally just a synonym for "standard deviation" in statistics. The moment you make that connection, everything else finally makes real sense. It has to do with the Copenhagen interpretation of quantum mechanics, wherein the wavefunction represents a wave of probability for experimental measurements.
How ironic that you title the video "I don't think is means what you think it means," when you fell right into the most popular misconception of UP---it doesn't mean what you think it means!
So what you're saying is that if I put a cat in a box, I'm uncertain about it being alive or dead, because the radiation are quantum waves? But, if I observe it, the radiation waves become radiations particles that makes the cat a zombie both alive and dead?
Do you know the Young's Double Slit Experiment(YDSE)?
If you dont know then go google or youtube it and look at the diagrams , it will help you picture the following stuff better.
Consider a double slit and on the screen there are detectors.
In YDSE when a light source emits light, the light goes through the 2 slits and makes an interference pattern on the screen. The light behaves as waves
Now say we take a gun which shoots out electrons and replace it with the light source.
There are detectors on screen(or a sensitive screen) , so if a electron falls on a part of the screen, we know. So we fire 1 million of electrons, 1 after the other and we observe the data. The data suggests that the electron is like a wave going through double slit , There are points on screen where most of the electrons have landed and where none ( like a diffraction pattern for light , bright fringes and dark fringes). Because of this data we can tell the probability of an electron falling on certain part of the screen . Like out of those 1 million electron most of them fall on a point/band 'x' on the screen and none on point/band 'y' on the screen(multiples x and y , think of x as bright fringes and y as dark fringes). Now we can tell that there is high probability that if we fire another electron through the double slit , it will land on 'x'. And less probabilt that it will land on 'y'.
But , We don't know which slit it is going through. It will either go through slit 1 or slit 2.
BUT THE FREAKING SCREEN PATTERN(x's and y's) SUGGESTS THAT 1 ELECTRON GOES THROUGH BOTH THE SLITS AT THE SAME TIME !!! Its like the electrons know that there is another slit present.
So now we put up detectors in front of the slits ( between the slits and the screen). Now we can see/observe which slit an electron goes through each time.
Now the thing which throws us off is that AFTER observing which slit it goes through , the x and y pattern no longer holds true, it collapses! If we detect that its going through slit 1(or s2) , it falls somewhere else on the screen instead of falling on 'x'.
That is, it no longer behaves as a wave but as a particle.
Its our observation which forces the electron to behave like a particle.
To sum it up , if we don't observe it going through a particular slit , then it behaves as if its a wave going through both the slits at same time and creating a diffraction pattern , but if we observe which slit it goes through , it behaves like a particle and doesn't create that diffraction pattern.
But the crazy part is only one electron goes through the double slit at a instant . That is , it either goes through slit1 or through slit2 , not both.
Crazy right? Hopefully this makes it a bit less consfusing..
I'm sorry, I'm so sorry... just stop. You can not give the layman explanation and even come close to touching upon how absolutely complex the subject really is. If someone comes up to you and says they understand quantum mechanics, they do not, as those of us who've spent 20+ years studying it still do not understand why it works that way. See my comments on Schrodinger's Cat for more information.
I'd love to. For starters you can learn about standard physics and some nuclear physics. Quantum mechanics is such a strange beast in comparison, when you get down to it, there's a HUGE amount of both probability and extrapolation involved. The Double Slit Experiment and the uncertainty principle are great places to start.
cor well the thing is. In some situations light behaves like a particle. But under other circumstances it behaves like a wave. That's why we have wavelengths of light, but also the idea of a light particle, the photon. It's called wavs/particle duality.
Niels Borh was Danish :D and so were Ole Rømer, and H.C.Ørsted, both of whom also made significan contributions to Science :D Ole Rømer, for example, found that light has a finite (albeit very large) speed, and H.C.Ørsted discovered the connection between electricity and magnetism, or electromagnetism as it's also known. YAY Denmark :D
couldn't you measure the velocity in terms of how long it takes the particle to jump the planck's length, and say that the particle can only exist on those points, then by identifying where something was, you can limit all the places it could be and thus know where it is.
Although they are not exactly the same thing they are related, one can study the observer effect and essentially find a lower bound for the product of the errors of position and momentum and this lower bound turns out to have the same form as the Uncertainty principle.
The famous movie quote the phrase is based on uses "it," but only because a "that" was used just prior: "You keep using *that* word... I do not think *it* means what you think it means."
Hank probably based the title on the direct quote as a reference, but chose to actually say "that" because the phrase doesn't actually make sense without a demonstrative somewhere. It does make for a weird inconsistency, but at least it makes a little sense if you think of it in terms of the quote.
I'm always bugged when the term "collision" is used when describing the eventual merging of the Milky way and Andromeda galaxies. I feel it defiantly gives the "I don't think it means what you think it means" vibe.
So, the more you know about something's velocity, the less you know about it's position? And it doesn't have a specific position?
No shit, it's moving. You're uncertain where its moving? That's because it exists in the quantum world. OF course there are millions of possibilities we are unaware of.
+flerper derper But even if something is moving (like a car) we can still know its position at a given point in time. What this video is trying to explain is that the more we know about a particle's velocity, the less we will know about where that particle is at a given time. We will only know how likely a particle is to be at that point in time, and will only have a probability distribution. As in, if we were to work out a particle's velocity, and then take a snapshot of it, if the particle was something large like a car we would see where the car was in that snapshot, but with a particle we wouldn't - we would just have a probability distribution of where the particle was likely to be at that moment.
So wait, we can't even identify a particle's position and momentum in a 1:35 mathematical model? Why is it that we can't just state "Assume a neutrino at (0,0,0) moving with 6i + 7j + 8k" or any other equivalent statement?
+Austin Kreulach Because a particle cannot physically be at just one location... that would be a terrible assumption to make... not at all indicative of how subatomic particles work.
You would have to assume a neutrino is in this general field with a probability of being here, there, and there to make an accurate or meaningful model... apparently...
I have a very good way of explaining it.
Imagine a car moving at certain velocity, you can know its velocity because you can calculate but you cannot know its position because it is moving. If you want to know its position you have to pause the video but when you pause the video you no longer know its velocity.(the velocity you calculated before cannot be taken into account)
+Madhab Koirala You got it wrong. When you paused the video you chopped the information into a tiny useless information. We can keep tracking the car position and its momentum by watching the whole video. However, for atomic particle the act of watching will effect behaviours of the particle, we can't keep tracking both position and momentum when we start to look at it.
HOW DOES THE PARTICLE KNOW THAT IT IS GOING THROUGH THE SLIT?!?!?! This is driving me crazy. I shine the laser through the slit, and the beam dramatically widens. But how does the particle know that it is going through the slit? what is the difference of going through the slit and the air? It can't be interacting with the slit, can it? wouldn't interacting with it mean hitting it and stopping? If anyone can help me understand this, please help; I would greatly appreciate it.
The REASON that the Heisenberg Uncertainty Principle is inexorably connected to the Observer Effect is because Virtual Particles only exist as a 'cloud of probability' until condensed to Specificity through Observation - also understood as Interactions.
every sentence trails off in volume and then the next is edited to begin abruptly afterward at higher volume - makes for a poor quality presentation. Good content poorly presented, or at least poorly edited.
Experiment: Cloud Chamber...when observing the vapor trails left by cosmic rays crossing the cloud chamber...the vapor trails have very specific positions, trajectories, and velocities...why does this not violate the uncertainty principle?
+Andrew Carlisle that's because those trails are trails in methanol where the high energy particles interacted with the methanol molecules, this means the particles were never really acting like waves to begin with for several reasons
small wavelenght (these are super energic particles) , and continuous interaction which collapses the wavelenght
basicly, when a quantum particle is interacting, you no longer have a quantum particle, you have a classical sistem of particle - neighboor particle
+Andrew Carlisle Not that specific. The uncertainty principle states that the product of the uncertainties (really standard deviation) of the position and velocity of a particle must exceed a very small number (Plank's constant over two). You can't measure a particle's position to anything like that accuracy in a cloud/bubble chamber.
I don't get it...it seems that if you confine an electron beam in a very strong magnetic field loop you will know the precise velocity and trajectory of the electrons...put that field in a glass bulb that glows due to the passage of the electrons and you will know the precise location as well...seems to me we did this in physics lab back in college in an experiment to measure the charge and mass of the electron.
+1001JungE But great topic in general if scishow decides to dive into mathematical questions. It's mostly typical science though. I think numberphile has already done videos about infinite series' like that, since they're about mathematics more than other sciences.
Maybe a co-op video between numberphile and scishow where they talk about where various mathematical nonsense appears in nature, like the golden ratio appearing with shells and the fibonacci sequence with flower petals.
+1001JungE No, you're just flawed in how you're asking, which he already pointed out to you.
He asked what it is people don't understand about infinity, and instead of explaining what people don't understand, you cited infinite /mathematical problems/ that people have already solved and explained as if it proved that people don't know what infinity is.
Infinity itself is just something that never ends.
When someone doesn't understand an infinite mathematical problem, that doesn't mean they don't understand infinity. Almost everyone understands infinity. It means they don't understand the infinite mathematical problem.
Instead of claiming people need to learn what infinity is and understand it, which almost everyone already does, and acting smug when someone who knows better English than you points out the problem of your post, realize the better phrasing is "Do a video on how infinite mathematical problems work' rather than 'Do a video on what infinity means'. People already know what infinity means, and there's rarely a misunderstanding about what an infinite mathematical problem /is/. The only issue is that most people don't know /why/ mathematical problems relating to infinity have strange answers. So, even if they make a video on it, it doesn't belong with IDTIMWYTIM.
Thank you john green for your insite on hisenburg it really helps on my year 10 gcse chemistry as I'm goin for A* distinction which is a higher level thank you (in america this would be also known as A+ and extracredit )
+SDG Heather I'm in England, and I'm in the same year as you (moving into Year 11 after the holidays) and at no point for my science coursework did i have to write about a physician, nor do i understand John Green's relevance to this video and Heisenberg's uncertainty law. Not only this, in your first comment you were talking about chemistry, then in your more resent comment you go on to talk about physics. I understand you comment was from some time ago, however I just can't get my brain to understand your logic.
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