Thank you! I learned about the Fourier Transform 20 years ago in college but never imagined that it would relate to the Heisenberg Uncertainty Principal. I love it when something you learn connects to something else, even years later! Thank you good sir!
I have to say that was one of the best explanations of the real meaning behind the uncertainty principle I have ever heard. Thank you Dr. Lincoln. I really appreciate you taking the time to sit down and chat about these various topics. They have all been good, but this was the most enlightening for me personally.
Indeed, at first I also thought the same like you. But when adding more waves gave the position and not the velocity, I said to y self that there is some thing wrong with considering the delta function indicating position and not velocity. Indeed, how do you arrive at determinism from probability isn't clear, Fermi lab.
This video is the best explanation of the Uncertainty Principle I've ever seen. It really should be interpreted in the context of Fourier Transformation.
2:30 That's what I learned in high school as well. Finally in digital signal processing course at the university I learned how waves work and immediately knew that's the real thing behind Heisenberg's theory.
Wave mechanics is just one representation of quantum mechanics. I think the reason is even deeper. I think the true essence of quantum mechanics is the non commutative algebra of observables.
This was a great episode, I was likewise told an incorrect interpretation of the uncertainty principle. I think Sub atomic stories is your best series yet.
Thank you so much for explaining this. Having taken calculus courses, this makes sense. This also demystifies the point so that it is a clearly understood principle with discreet variables rather than the mystical paradox it is often presented as.
sir i have recently started following you like from the time of lockdown in my country. i love physics. I am blown to gain such massive amounts of knowledge that you provide , I admire you so much thanks for giving me a role model. now i wish to pursue a career in physics.
It's beyond me how people try to teach this without pointing to the Fourier Transform. I'm glad to see that you did it. That said, you should have also spoken about information and which domain it's present in a bit more. Bosons are in the space domain (stretched out) and does not change in time (specific). Fermions are a little bit in both unless they are at absolute zero and all of their information would be in the time domain (stretched out) and not in space (specific).
On the pronunciation of ν and other Greek letters. "Nee" is the modern Greek pronunciation, whereas "noo" is a very ancient Greek pronunciation. There are numerous changes in pronunciation that have happened in the history of the Greek language(s), and one of the most notable is called "iotacism", which is really a whole bunch of different changes, but refers to the fact that many different vowels and diphthongs in Ancient Greek have somehow all become "ee" in Modern Greek. Since the most famous works of Greek literature and philosophy, including early work in math and physics, come from over 2000 years ago, it is Ancient Greek that learned Europeans studied in the middle ages and Renaissance, and it is this tradition that led scientists and mathematicians to think of Greek letters as convenient symbols. Thus, common parlance about how to pronounce Greek letters also comes from this tradition of studying Ancient Greek. However, it is not so simple as saying that Ancient Greek pronunciations are used in math and physics. The issue is that people in this long European tradition of studying Ancient Greek mostly didn't really know, or even care very much, how Ancient Greek was ACTUALLY pronounced. (To some extent the reconstruction of actual ancient pronunciations is really more of a modern phenomenon that got going with the development of modern historical linguistics in the 19th century; however, there were attempts to do such long before that.) Thus, there are actually numerous traditional pronunciations of Greek that developed in different European countries where people spoke different languages. These are often influenced by the native languages of the different countries; in particular, (1): Greek words could essentially become like native words of the language of an academic community familiar with them, and their pronunciations would then change according to the same phonetic rules that changed the native language of that community over the centuries, and (2): When Greek words are spelled out "phonetically" in non-Greek writing systems, people tend to read those spellings as if they were native words of their own native language, even if those "phonetic" transcriptions are designed to be read in a certain non-obvious way or were designed for an older version of their native language that had different correspondences between letters and sounds. For instance, I tend to pronounce μ and ν as "myoo" and "nyoo", which arguably makes sense for 3 reasons: (1) These are the ways I first heard these letters pronounced, (2) These are reasonable readings of the traditional "phonetic" spellings "mu" and "nu", according to modern English spelling-sound correspondences, and (3) The very ancient Greek "oo" sound (υ) became fronted to sound more like the French "u" or German "ü" in most situations even before Alexander the Great in Attic (Athenian) and Ionic Greek. While this sound eventually came to sound like "ee" in Modern Greek (after staying around through much of the Middle Ages), that is not what happened in French. In French, an old Latin "oo" sound (French is descended from Latin) became a fronted, much like what happen in Ancient Greek. When the English language became flooded by French loan words after the Norman conquest, and after various vowel changes in the English language between then and now, these "u"s from French are now generally pronounced as "yoo" (which is the reason why "u" is often pronounced "yoo" in English and "myoo" and "nyoo" are reasonable English pronunciations of the spellings "mu" and "nu"). It also seems quite natural that the French would match up the Greek "υ" sound with their own basically identical fronted "u" sound, and with this traditional correspondence of this fronted "u" sound to an English "yoo", it only seems reasonable that the same thing might happen in English to the Greek "υ"-sound, especially if they were often introduced to it by the French. It's actually quite likely this is not true, because the Romans invented the letter "y" to transcribe the fronted Greek "υ" sound, and this is pronounced "ee" in the French words derived from Greek, at least when they come from Greek words that were borrowed into Latin; however, there were multiple attempts in the Renaissance to reform pronunciation of Ancient Greek to more authentically match ancient pronunciation, and my "myoo" and "nyoo" pronunciations might somehow be descended from such an attempt, similar to how the reformed pronunciation proposed by the Dutch scholar Erasmus's 1486 reconstruction of Ancient Greek pronunciation (which was adapted and popularized in England by Cheke and Smith in 1540) started a tradition of pronouncing Greek in English speaking countries that was then greatly distorted by vowel changes that happened in the last 500 years, such as the tail end of the "Great Vowel Shift". (Although I said there were multiple attempts to reform the pronunciation, I think most of them were based on Erasmus's reconstruction. It should be noted that I actually just looked Wikipedia because I realized that I was starting to write about things I didn't really know.) These traditional pronunciations also may have influences from the Latin pronunciations of Greek words (since the Romans incorporated lots of Greek words first, and then Latin became the language of learning in Europe for centuries), as well as from various later versions of Greek, such as Byzantine Greek and Modern Greek. (Keep in mind it's a continuum, languages change slowly over time; they don't just suddenly morph into different languages.) This influence from later versions of Greek no doubt comes from things like the person who corrected his pronunciation from "noo" to "nee", i.e., it comes from the idea that whatever they say in Greece now must be the actual "correct" pronunciation (with some maybe even thinking it's the original pronunciation, due to not considering language change). The idea of "correctness" is fundamentally pretty arbitrary, so it's hard for me to say that it's wrong to think that, but it is a bit misguided to assume that everyone should just change their pronunciation to match the Modern Greek pronunciations without justifying why this is better. An example of influence from later versions of Greek, and also somewhat from Latin, is the pronunciations of the Greek letters φ="phi", θ="theta", and χ="chi" with the English "f", "th", and "k", sounds. The romanizations "ph", "th", and "ch", were invented by the Romans to transliterate Greek. In Pre-Roman Greek (and probably also in Early the Roman Period), these letters were pronounced like "p", "t", and "k" (followed by a puff of air, like how we pronounce them at the beginning of words in English); however, between the Roman and Medieval periods, the pronunciation of these sounds softened to sound like "f", "th", and a raspy sound similar to the Spanish "j" or the German "ch". These new pronunciations were prevalent in Greece throughout the entire history of the English language, and the fact that we write our "th" sound the way do is probably by analogy to Medieval Greek (since "th" was the normal romanization of θ, which was pronounced this way). Back in Middle Ages, when English had that raspy sound like German and Spanish do, it was often spelled "ch", as it still is in German, by a similar analogy with Medieval Greek, (although the spelling "gh" is what we generally see in Modern English spellings of words that used to have this sound, like "though", and "night"). The medieval and Modern Greek pronunciations of these sounds (which are "unvoiced fricatives", by the way) have almost always been the preferred pronunciations of these sounds in medieval, Renaissance, and modern times alike, no doubt because that has been the pronunciation in Greece throughout all of these time periods, despite that the fact that these are not the pronunciations that Homer, Plato, Aristotle, Euclid, or most of the other famous Ancient Greeks would have used. This also shows influence from native language phonology. English has the Modern Greek φ аnd θ sounds, but no longer has the χ sound; French has only the φ sound; and German has the φ and χ sounds, but not the θ sound. As it happens, all these languages use the Ancient-Greek-like ("p"), "t", "k" values when they don't have the Modern-Greek-like sounds (or rather, people who aren't studying Greek seriously use these sounds for the stray Greek words and letters that come up), though I think Germans often match French and use "k" for the χ-sound, even though they theoretically know how to say a sound like the Modern Greek sound. (This probably mostly has to do with the fact that the German "ch" sound usually only occurs in certain parts of words, at least in "standard" dialects.)
OML this is such a great explanation! I always saw Heisenberg uncertainty explained as a measurement problem. The wave freq vs localization makes so much more sense! Thanks!
Very well explained, better than my former college professors. You have a gift for teaching. Although I would add that the "wrong" observational explanation you provide is also true, however it would be true in principle also for classical systems, while -as you explained- the Heisenberg uncertainty is rather an intrinsic feature of matter.
What is the corresponding equation for angular momentum? Delta L Delta theta < hbar/2? Are there other equations for other conserved quantities like electric charge and quantum info?
For total angular momentum there is a similar inequality when looking at angular momentum in perpendicular planes. en.wikipedia.org/wiki/Uncertainty_principle#Examples For charge and quantum information there is no such uncertainty inequality, since they are not operators in quantum mechanics. Their conservation is explained in different terms.
Thank you, Dr Lincoln! Like you, my earlier education experience provided “a less than helpful “ explanation of the Heisenberg Uncertainty. And I have still struggled with the details all of these years, especially if trying to describe it to someone else. NOW I feel that I have finally GOT it (at least more) cemented in my head! Thanks to you for taking the effort to help clear this difficult subject 😊 for All of us; great video.
Cool....didn't know about the time/energy application of Heisenberg's Uncertainty Principle...I LOVE learning new (to me) aspects of scientific principles (and getting more accurate explanations)....Thank you!
I studied engineering in college decades ago, which made a video I watched on RUclips several years ago make the Uncertainty Principle click. It said the same thing you did, that the momentum and matter (i.e. position) waves are Fourier duals.
I love watching all these, but I'm an old man and I'd be lying if I said I understand all this stuff, but I think I kinda get some of it , so keep em coming please.....
I watch your videos whenever I get the chance and all I can say is --Thanks! I guess I was lucky and got a decent understanding of the Heisenberg Uncertainty principle from my Prof's but I have to admit yours offered a nice, short, and concise conceptualization.
Thanks for your videos, Dr Lincoln. I am anything but a physicist, but you have helped familiarize me with current thinking. I sincerely appreciate that. I have 2 questions (I apologize if they are stupid ones): 1. If I understand correctly (& please correct me if I am not), the galaxies are flying apart from one another not as objects flying outward from the original explosive Big Bang, but as a phenomenon of constantly expanding space pulling them apart. Yet you mention in this segment that matter and antimatter annihilated one another in the Big Bang at a rate of 3 billion particles of matter to 3 billion particles of antimatter (with 1 particle of matter left over for each 3 billion destroyed after contact with 3 billion particles of antimatter). Shouldn't this massive matter/antimatter contact have created an unimaginably powerful explosion, that Big Bang which would explain the spread of all matter outward from the point of the original singularity?; 2. Does that combination of 6 billion particles of matter + antimatter whose annihilating contact left over 1 particle each of the matter that comprises the universe today indicate that at the instant the Big Bang happened, the mass of the universe (in the singularity) was almost infinitely greater than what has been left over in the universe as we know it? Is there enough radiation in the Cosmic Microwave Background to account for all the Gamma Rays released in an explosion of such incredible size?
Excellent. Thank you. -------------------- For me personally modern physics & its vastly developed fields are important for curbing aside all forms of anthropic misconcepts of the post Aristotle periods. And Heisenberg's Uncertainty, although at Quantum levels, but it also reminds us of indeterminism in evolutionary history, which many branches of different human hybrids have falsely treated with certainty/ deterministically.
Enlightening!!! Great explanation!!! Amazing series... pls continue posting amazing videos... I have seldom come across such reliable and interesting source of correct explanation for such complex topics.
Hey Dr. Don. In your response to the last question in this video you said that the CMB is due to the annihilation of matter with antimatter in the early universe. Some sources say that the CMB is caused by the (re!)combination of electrons with protons to form neutral hydrogen when the universe was about 300K years old. Do these 2 mechanisms (matter/anti-matter annihilation and electron/proton recombination) both contribute to the CMB? If so, are there two distince CMB signatures that reflect the different initial energies and origination times? Thanks as always for a very interesting series!
I've always understood it as since having a wavelength and thus motion, there's necessarily a tradeoff between knowing how fast they're moving during a period of time, or where there were at a specific instance in time. I sort of think of knowing the location exactly like looking at a picture of the particle. Yes, you can clearly see where it is when it's not moving. Maybe this is a flawed intuition, in which case anyone should feel free to let me know what i got confused here. :)
Well I'm a little clearer. I get the FFTs, used those in the past. So there's a trade off between positional and energy information. Certainly the analogy of hitting the particle with a photon is wrong but I suppose it's a place to start. Not one that my A-Level Chemistry teacher used, but I remember the first test we had in A-Level Chemistry and there was a very high uncertainty factor indeed. It was a brutal shock that made us realise just how much harder A-Level was than O-Level/GCSE (UK school examinations).
At university (before the top quark had been discovered) I came up with the idea of gravity being the cause of all forces, which in turn gives rise to particles. The idea is that space is moving (in 3 dimensions) and that movement causes areas of space to be both expanding AND collapsing. Collapsing space accelerates towards the speed of light which results in tiny areas (points) of the field of moving space appearing "permanent". That is, a particle is not an actual "thing" but an area of very fast moving space.
Hi Don. Why do we superimpose waves from multiple objects to create a wave function when we only want to know the position and momentum of one object? Once we superimpose the wave to create a wave function, out of all the objects which are contributing their wavelengths, how can we be sure the wave function that is the outcome helps us determine the position and momentum of the intended objects and not other objects?
Probably answered in a previous video, but... What happens as particles cool down near absolute zero? Don't their position and momentum both become more restricted and well known? (i.e. both become less uncertain at the same time?)
At absolute zero, there are so-called zero oscillations. They are exactly the size (energy) defined by the heissenberg uncertainty principle. For example, if you have an atom in a lattice (eg. crystal of ice), then each of those atom vibrates with the energy of hf/2 (planck's constant times frequency over two), which is the h/2 uncertainty defined by heissenberg. Then, even at zero kelvin, the atom oscillates (in 3D it would be 3hf/2, for three dimensions) around the equilibrium with an unknown direction of the oscillation (front-back, up-down, left-right or its combinations). Edit: the correct term is zero-point oscillation in English, sorry for that.
Awesome series!! Thanks a lot for doing this and making physics understandable and approachable by anyone!! I used to live near Fermi lab and always wanted to visit. I hope I can one day! Brilliant!
I am frankly concerned and curious as to why this particular channel doesn't have a higher subscription rate. Its FermiLab folk!! Not some goober with a grasp of physics but no clout( yes that sort of thing counts in believability and school choices). I've heard of this guy before I came across the channel. Now I'm not saying the other lads aren't on the ball or inaccurate, hell some of their info was probably from FermiLab. I'm just saying history, pedigree, veracity means a lot. It's just human nature I suppose. Anyway I read about1 Enrico Fermi in the 4th grade for kicks instead of sports. As a result I had a career, family, a measure of success somewhat larger then Max Planck's rather intriguing constant though I prefer the unredacted version just to terrorize students and new teachers. I expect a more rarefied appeal from Utbes proudly jaded Higher Branch MatheAddicts. Please excuse my waaaaay too stylized writing. I've not had coffee yet. Hi Mr. Lincoln. -douglas
My thinking uncertainly exact! It doesn't get better than Fermilab and having someone that can reveal things without excessive "dumbing down" is great at the same time not throwing a blizzard of integrals that glaze my eyes over.
I am absolutely enjoying this series. Keep it up! Was your description of the uncertainty principle at all inspired by Prof. P Moriarty’s video on the subject?
Hi, Dr. Lincoln. Thanks to you and the Fermilab team for putting this series together. I have some quantum skeptic friends that aren't convinced by theory alone that the uncertainty principle is anything deeper than the observer effect. Is there any experimental evidence that discredits this idea?
great series. so i was among the "uncertainty is just a human measurement deficit" crowd at first but by watching a lot of youtube videos by you, sabine hossenfelder, 3blue1brown and parth g, i arrived at the fourier transformation explanation by which physicists claim its a property of the universe. what still bugs me is the following: if i understood correctly, the schrödinger equation, which all of this is based on, is itself just an assumption, a postulate. i heard even the most brilliant physicists claim that noone actually understands what it is, but as it produces valid predictions everyone just uses it. so, however mathematically rigorous the deduction of the uncertainty principle being a fourier transform of solutions to the schrödinger equation may be, its still the mathematically rigorous deduction from an assumption. it sounds like quite the stretch to me to call that a "property of the universe", the foundation seems to be very shaky especially as there is still the damokles sword of gravity and general relativity not being unifiable with quantum theory, which makes errors or gaps in any of these theories highly likely. could you maybe elaborate on that, id love to understand more about the foundations that quantum mechanics (and general relatitivity and a theory of everything) stand on. i also once heard, that there are alternatives to the schrödinger equation (by heisenberg) and that schrödingers proposal was used because it was "easier to use". is that correct and what are the details? and a last, totally unrelated question: all calculations and equations are fine and dandy but they dont explain the mechanisms of how things work. example: equations and measurements confirm that the speed of light is measured the same by every observer regardless of their own movement (hope that phrases it somewhat correctly). but has anyone ever tried to work out a kind of mechanism by which that would be possible?
I have a similar question about quantum randomness. Some physicists say the universe is deterministic and the appearance of randomness is just our ignorance/uncertainty of the precise values. This video didn't mention randomness, but randomness is intimately related to some interpretations of the Heisenberg uncertainty principle, and a discussion of quantum randomness would be appreciated.
@Michael Bishop an equation does not describe a mechanism, it enables you to calculate the output of one and maybe gives you the contributing factors.
There's so much I still don't understand: 1) How does one even go about measuring the properties of particles? 2) What sort of readings would you get back if you tried to simultaneously determine the position and momentum of, say, an electron? 3) Given that measurements have to be taken sequentially, what does a 'simultaneous' measurement even mean? 4) Related to three: given how fast something like a photon or an electron moves through space, don't measurements of their position or momentum tell you where that particle was or how fast it was travelling however long ago you measured it, rather than what it's doing or where it is 'now'?
What properties of a particle are you trying to measure? It's mass, it's position, it's charge, it's kinetic energy? Different techniques are used to measure different things. The uncertainty principle is technically not about measurement. To the best of our knowledge right now, things don't simultaneously have an exact position and an exact momentum at the same time. Because particles have a wave nature, if you finally do measure the exact position of a particle, say you have it run into something and you see exactly where it landed, you no longer have any information about its wavelength. That information is destroyed. The term is called the collapse of the wave function. Also, if you measure the wavelength of the particle, you really can't know exactly where the particle is. There are a lot of good videos about that. Look up the ones from 60 symbols about the Heisenberg insert new principal. Those are good. It's difficult to understand and it's difficult to come up with exact analogies. Quantum stuff is just weird. Other ways to measure properties of a particle... shoot a particle with a known speed through a magnetic field, you watch how much the particle curves. If it has a charge, you can take that length of that curve and the angle it's deflected and calculate the particles mass and then it's kinetic energy and things like that. Keep studying and keep learning. Physics is fascinating, but it takes years to learn a lot of it because much of it is beyond our everyday experience.
It is somewhat similar to producing beats in sound by mixing sound waves of different frequencies. Notice, I said similar, so don't take the analogy literally. That being said, we can get a very rough idea of what is going on by examining beats in sound. Mixing sounds of different frequencies results in interference patterns that result in localized areas of maximum amplitude and areas of zero or close to zero amplitude, so the waves are localized, and deliver their energies in bursts (beats). The whole live cat dead cat existing simultaneously scenario in the Schrodinger's Cat story was originally meant to be a derisive commentary on the absurdity of quantum mechanics. Somehow it morphed into an accepted explanation. Just as the term 'Big Bang' was a derisive term at first and was somehow adopted by the physics community as an acceptable term, even though there was no bang as erroneously depicted in so many science videos.
If the 'space' in the universe is expanding, do the particles and the fields they interact with also expand? In other words does a quark, neutrino, or any particle's waveform also get stretched out? Or does their size remain constant and they just inhabit more 'space'?
@Dr Deuteron I guess what I'm thinking is if the universe is expanding, and EVERYTHING scaled at the same rate, we wouldn't even see that expansion. So if subatomic particles are wave forms within fields, why don't they also 'expand' along with the space they inhabit? (I'm probably not explaining this very well.)
@@aaronnatera3685 it's not that space is getting less dense as it expands, when it expands it essentially generates new space with it's own vacuum energy. This is the only way to get the exponential expansion we see, if space scaled then even with vacuum energy the expansion would be linear.
Yes, particles also get stretched, this is exactly why the cosmic microwave background radiation today has such a long wavelength, corresponding to very low temperature, while it was born with much more energy (and shorter wavelength) corresponding to much higher temperature.
Thanks for all the replys. I think understanding the answer. Basically 'new' space is added, (along with its vacuum energy), but nothing 'new' is being added to the various fields that produce particles. They simply inhabit and travel through more space than before. Correct?
Everything gets stretched, including particles, but the forces holding particles together is greater than the expansion of the universe, so their size doesn't change. And if it did change, the amount would be a measurably tiny, and as I understand, it's smaller than the Heisenberg uncertainty principle would allow us to even come close to measuring. That's an insightful question. Good job!
Hi Mr Don. what sizes do elementary particles have? For example, the electron is considered as point like particle, but, if it is pointlike, then it should be a black hole, which in turn should evaporate quickly. So, electron is considered pointlike because we cannot measure size, or, it really does not have any length?
There's a 3Blue1Brown (math-animation&explanation) video about the uncertainty principle, and where it shows up both inside and outside of physics: "The more general uncertainty priniciple, beyond quantum"
In your answer to the question about matter-antimatter annihilation, it was asked where the energy went and your answer was the CMB. I thought the CMB was for the big bang, not the annihilation energy? Are these linked or independent sources of CMB?
Well for the first ~380000 years the universe wasn't transparent (like a star is not transparent), so the CMB is radiation produced at that later period when it finally became transparent. Not quite the early stages of the big bang.
I'm not sure it's been said, but I've always thought a good way to explain it to people who don't get it is to imagine taking a picture of a bright yellow/green tennis ball, thrown in no specific direction in a clear blue sky. The more crisp the picture, the less information you have on the direction/momentum of travel. However, if you get the blurr effect of movement, you get a more accurate indication of those measurements, but less information on its exact location. I'm not sure how accurate that is? But it always made sense in my head, at least.
They are described by same kind of waves so they have the same mathematical properties regarding this uncertainty. What they differ in, is the mass-energy-momentum ratio, they don't have to be "on the mass shell".
Dear Don, On the question about neutrinos penetrating a neutron star, you talk about a low energy muon-neutrino turning into a muon and a low energy electron-neutrino interacting with a proton, turning it into a neutron. Please elaborate on that, as (in the latter case) I thought it takes at least an electron (also) (with a very much defined energy as you previously stated) to turn a proton into a neutron (conservation of charge). Or have you forgotten to mention something?
In a previous video you talked about how mass actually doesn't increase when velocity reaches relativistic speeds. Could you please explain that a little bit?
There are more science channels to the rescue: Sci Show / Microcosmos (general popular science) Kurzgesagt (scientific stuff with a moral) Launchpad Astronomy (accurate science facts on astronomy) PBS Spacetime (specialized science, math free) Isaac Arthur (science and speculation on the future of humanity) Many of Brady Haran's videos with the University of Nottingham Royal Institution (recorded public lectures) Anton Petrov (astrophysics papers summarized)
Dr Lincoln thank you for your fascinating video series. I have been puzzled since high school at the extremely uniform masses of the electron and proton. You have made the mass uniformity of the electron perfectly clear. However I have learned from your videos that the internal mechanisms of the proton are very complex. Is the proton mass as equally uniform from proton to proton as the electron?
I understood some of this so I have a bit of a better understanding which is cool. I still have a long way to go. Thanks for getting me just a little bit further :)
Is it actually necessary to use particles to describe "particle physics" at all, or could we just say that everything is waves in fields and not resort to particles at all?
Sir, I think I have another valid argument against this observer effect! I would like to know your opinion on my argument if you deem it fit and sensible enough to reply because I might be wrong and even foolish here :) This observer effect of using light to determine position of electron with a simultaneously change in electron's momentum is not Heisenberg uncertainty principle because this will only produce RANDOM scattering of electrons on the other side of the slit in the famous double slit experiment and NOT the proper INTERFERENCE pattern which we usually see! This observer effect cant produce observed interference pattern but only random non-interference pattern on the screen as seen in the case of wave-particle duality of matter.... So, we should not confuse Heisenberg Uncertainty principle with observer effect .... Am I right or wrong ? I would like to know your answer ....
I understand the momentum and matter waves, and that the Uncertainty Principle means they’re Fourier duals. But for the alternative form of energy vs time, what are the physical interpretations of the “energy wave” and “time wave” (functions)?
It already does: many galaxies we see are currently receding faster than light. Hubble law for the expansion says every second all large distances get multiplied by a constant k. It means you can always find a distance L such that it in one second it increases more than light goes in one second: ktL - L > ct.
Also, that's why you sometimes talk about the "observable universe" - we cannot see beyond, since the far parts are moving at more than several lightspeeds away from us. (why we can see things moving away more than one lightspeed fast would be a good topic for another video :) )
I have a specific example in mind: using laser we send single photons threw a hole (the size of the photon) into a detector. We know exactly the energy (frequency) of every photon, their speed (c) and we know that if the photons were detected, they must have been in a specific location (they went threw the hole). In short: we know everything about the particle in one moment of it's life. Can someone please explain to me, why this example doesn't break the Heisenberg's Uncertainty Principle? Thank you in advance.
A photon is wave, not a particle, while it is alive. It doesn’t have a definite position until it is measured, which is when it dies. The best you could do is send a single wave pulse of a specific energy through the hole. It's not clear to me what the size of a photon would be either. It's wavelength? It has no height or width.
In one episode of ST:TNG there was a "Heisenberg compensator". Which worked around the problems caused by the Heisenberg Uncertainty Principle, allowing the transporter sensors to compensate for their inability to determine both the position and momentum of the target particles to the same degree of accuracy. This ensured the matter stream remained coherent during transport, and no data was lost. How can that thing be built?
Thank you Sir at last after long time now understand what is Heisenberg uncertainty principle. I need a clarification, can Heisenberg uncertainty principle address teleportation from quantum level to molecular level, like predicting velocity of an moving object and relative velocity required by the mass to travel along with predicting the position of objects moving in a path
![Kodak Black - Versatile 4 [Official Video]](http://i.ytimg.com/vi/VcP_1Ua__vY/mqdefault.jpg)
This may continue as far as im concerned. This is a great series!
That’s amazing how generous people are these days!
it pieces everything together
Agree 100% with no uncertainty :)
Ive been following fermilabs for a few years now, but this series is just so chill. Im always learning, but in this format it feels great!!!!
Please specify. Thanks.
Ana M. Abreu. 08/21/20.
Thank you! I learned about the Fourier Transform 20 years ago in college but never imagined that it would relate to the Heisenberg Uncertainty Principal. I love it when something you learn connects to something else, even years later! Thank you good sir!
I have to say that was one of the best explanations of the real meaning behind the uncertainty principle I have ever heard. Thank you Dr. Lincoln. I really appreciate you taking the time to sit down and chat about these various topics. They have all been good, but this was the most enlightening for me personally.
Indeed, at first I also thought the same like you. But when adding more waves gave the position and not the velocity, I said to y self that there is some thing wrong with considering the delta function indicating position and not velocity. Indeed, how do you arrive at determinism from probability isn't clear, Fermi lab.
Best Heisenberg Uncertainty Principle Explanation I have heard so far! Thank you! I love the series!
Thank you Dr. Lincoln, I could watch and rewatch this series forever. It’s one of the best about physics.
Edit: Corrected mixup names. Sorry.
Fadi Fortuna hahaha! Corrected. One of my physics teacher was a *Don Franklin* and I always mixup names.
Please, dont stop doing this videos, are just great.
This video is the best explanation of the Uncertainty Principle I've ever seen. It really should be interpreted in the context of Fourier Transformation.
2:30
That's what I learned in high school as well. Finally in digital signal processing course at the university I learned how waves work and immediately knew that's the real thing behind Heisenberg's theory.
I got taught a lot of outdated and/or incomplete information regarding physics in school.
Wave mechanics is just one representation of quantum mechanics. I think the reason is even deeper. I think the true essence of quantum mechanics is the non commutative algebra of observables.
It’s a thing but it’s not the thing. The thing is non-commuting operators
This was a great episode, I was likewise told an incorrect interpretation of the uncertainty principle. I think Sub atomic stories is your best series yet.
Thank you so much for explaining this. Having taken calculus courses, this makes sense. This also demystifies the point so that it is a clearly understood principle with discreet variables rather than the mystical paradox it is often presented as.
Funny thing is, if you dig deeper into quantum mechanics its not founded on discrete variables and becomes mystical (from our classical view) again.
sir i have recently started following you like from the time of lockdown in my country.
i love physics. I am blown to gain such massive amounts of knowledge that you provide , I admire you so much thanks for giving me a role model.
now i wish to pursue a career in physics.
Do it. You'll never regret it.
It's beyond me how people try to teach this without pointing to the Fourier Transform. I'm glad to see that you did it.
That said, you should have also spoken about information and which domain it's present in a bit more.
Bosons are in the space domain (stretched out) and does not change in time (specific).
Fermions are a little bit in both unless they are at absolute zero and all of their information would be in the time domain (stretched out) and not in space (specific).
Something more,
The uncertainty in energy does point to mass, but it also points to what kind of energy it is.
On the pronunciation of ν and other Greek letters. "Nee" is the modern Greek pronunciation, whereas "noo" is a very ancient Greek pronunciation. There are numerous changes in pronunciation that have happened in the history of the Greek language(s), and one of the most notable is called "iotacism", which is really a whole bunch of different changes, but refers to the fact that many different vowels and diphthongs in Ancient Greek have somehow all become "ee" in Modern Greek.
Since the most famous works of Greek literature and philosophy, including early work in math and physics, come from over 2000 years ago, it is Ancient Greek that learned Europeans studied in the middle ages and Renaissance, and it is this tradition that led scientists and mathematicians to think of Greek letters as convenient symbols. Thus, common parlance about how to pronounce Greek letters also comes from this tradition of studying Ancient Greek.
However, it is not so simple as saying that Ancient Greek pronunciations are used in math and physics. The issue is that people in this long European tradition of studying Ancient Greek mostly didn't really know, or even care very much, how Ancient Greek was ACTUALLY pronounced. (To some extent the reconstruction of actual ancient pronunciations is really more of a modern phenomenon that got going with the development of modern historical linguistics in the 19th century; however, there were attempts to do such long before that.) Thus, there are actually numerous traditional pronunciations of Greek that developed in different European countries where people spoke different languages.
These are often influenced by the native languages of the different countries; in particular, (1): Greek words could essentially become like native words of the language of an academic community familiar with them, and their pronunciations would then change according to the same phonetic rules that changed the native language of that community over the centuries, and (2): When Greek words are spelled out "phonetically" in non-Greek writing systems, people tend to read those spellings as if they were native words of their own native language, even if those "phonetic" transcriptions are designed to be read in a certain non-obvious way or were designed for an older version of their native language that had different correspondences between letters and sounds.
For instance, I tend to pronounce μ and ν as "myoo" and "nyoo", which arguably makes sense for 3 reasons: (1) These are the ways I first heard these letters pronounced, (2) These are reasonable readings of the traditional "phonetic" spellings "mu" and "nu", according to modern English spelling-sound correspondences, and (3) The very ancient Greek "oo" sound (υ) became fronted to sound more like the French "u" or German "ü" in most situations even before Alexander the Great in Attic (Athenian) and Ionic Greek. While this sound eventually came to sound like "ee" in Modern Greek (after staying around through much of the Middle Ages), that is not what happened in French. In French, an old Latin "oo" sound (French is descended from Latin) became a fronted, much like what happen in Ancient Greek. When the English language became flooded by French loan words after the Norman conquest, and after various vowel changes in the English language between then and now, these "u"s from French are now generally pronounced as "yoo" (which is the reason why "u" is often pronounced "yoo" in English and "myoo" and "nyoo" are reasonable English pronunciations of the spellings "mu" and "nu"). It also seems quite natural that the French would match up the Greek "υ" sound with their own basically identical fronted "u" sound, and with this traditional correspondence of this fronted "u" sound to an English "yoo", it only seems reasonable that the same thing might happen in English to the Greek "υ"-sound, especially if they were often introduced to it by the French. It's actually quite likely this is not true, because the Romans invented the letter "y" to transcribe the fronted Greek "υ" sound, and this is pronounced "ee" in the French words derived from Greek, at least when they come from Greek words that were borrowed into Latin; however, there were multiple attempts in the Renaissance to reform pronunciation of Ancient Greek to more authentically match ancient pronunciation, and my "myoo" and "nyoo" pronunciations might somehow be descended from such an attempt, similar to how the reformed pronunciation proposed by the Dutch scholar Erasmus's 1486 reconstruction of Ancient Greek pronunciation (which was adapted and popularized in England by Cheke and Smith in 1540) started a tradition of pronouncing Greek in English speaking countries that was then greatly distorted by vowel changes that happened in the last 500 years, such as the tail end of the "Great Vowel Shift". (Although I said there were multiple attempts to reform the pronunciation, I think most of them were based on Erasmus's reconstruction. It should be noted that I actually just looked Wikipedia because I realized that I was starting to write about things I didn't really know.)
These traditional pronunciations also may have influences from the Latin pronunciations of Greek words (since the Romans incorporated lots of Greek words first, and then Latin became the language of learning in Europe for centuries), as well as from various later versions of Greek, such as Byzantine Greek and Modern Greek. (Keep in mind it's a continuum, languages change slowly over time; they don't just suddenly morph into different languages.) This influence from later versions of Greek no doubt comes from things like the person who corrected his pronunciation from "noo" to "nee", i.e., it comes from the idea that whatever they say in Greece now must be the actual "correct" pronunciation (with some maybe even thinking it's the original pronunciation, due to not considering language change). The idea of "correctness" is fundamentally pretty arbitrary, so it's hard for me to say that it's wrong to think that, but it is a bit misguided to assume that everyone should just change their pronunciation to match the Modern Greek pronunciations without justifying why this is better.
An example of influence from later versions of Greek, and also somewhat from Latin, is the pronunciations of the Greek letters φ="phi", θ="theta", and χ="chi" with the English "f", "th", and "k", sounds. The romanizations "ph", "th", and "ch", were invented by the Romans to transliterate Greek. In Pre-Roman Greek (and probably also in Early the Roman Period), these letters were pronounced like "p", "t", and "k" (followed by a puff of air, like how we pronounce them at the beginning of words in English); however, between the Roman and Medieval periods, the pronunciation of these sounds softened to sound like "f", "th", and a raspy sound similar to the Spanish "j" or the German "ch". These new pronunciations were prevalent in Greece throughout the entire history of the English language, and the fact that we write our "th" sound the way do is probably by analogy to Medieval Greek (since "th" was the normal romanization of θ, which was pronounced this way). Back in Middle Ages, when English had that raspy sound like German and Spanish do, it was often spelled "ch", as it still is in German, by a similar analogy with Medieval Greek, (although the spelling "gh" is what we generally see in Modern English spellings of words that used to have this sound, like "though", and "night"). The medieval and Modern Greek pronunciations of these sounds (which are "unvoiced fricatives", by the way) have almost always been the preferred pronunciations of these sounds in medieval, Renaissance, and modern times alike, no doubt because that has been the pronunciation in Greece throughout all of these time periods, despite that the fact that these are not the pronunciations that Homer, Plato, Aristotle, Euclid, or most of the other famous Ancient Greeks would have used.
This also shows influence from native language phonology. English has the Modern Greek φ аnd θ sounds, but no longer has the χ sound; French has only the φ sound; and German has the φ and χ sounds, but not the θ sound. As it happens, all these languages use the Ancient-Greek-like ("p"), "t", "k" values when they don't have the Modern-Greek-like sounds (or rather, people who aren't studying Greek seriously use these sounds for the stray Greek words and letters that come up), though I think Germans often match French and use "k" for the χ-sound, even though they theoretically know how to say a sound like the Modern Greek sound. (This probably mostly has to do with the fact that the German "ch" sound usually only occurs in certain parts of words, at least in "standard" dialects.)
Yes, I love these chats. I have learned a lot about things I read about 45 years ago. Keep it coming. Thanks and stay safe.
This is the best explanation of HUP I've seen, thank you Dr Lincoln
OML this is such a great explanation! I always saw Heisenberg uncertainty explained as a measurement problem. The wave freq vs localization makes so much more sense! Thanks!
Very well explained, better than my former college professors. You have a gift for teaching.
Although I would add that the "wrong" observational explanation you provide is also true, however it would be true in principle also for classical systems, while -as you explained- the Heisenberg uncertainty is rather an intrinsic feature of matter.
I'm just not sure about the Heisenberg Uncertainty Principle but I am certain your explanation is easy to understand and makes sense.
Please keep making these videos. They help me connect the different parts of physics together and just makes it even more interesting! Good work! :D
What is the corresponding equation for angular momentum? Delta L Delta theta < hbar/2? Are there other equations for other conserved quantities like electric charge and quantum info?
For total angular momentum there is a similar inequality when looking at angular momentum in perpendicular planes. en.wikipedia.org/wiki/Uncertainty_principle#Examples
For charge and quantum information there is no such uncertainty inequality, since they are not operators in quantum mechanics. Their conservation is explained in different terms.
Dr. Don, You're a national treasure!
This was a particularly charming episode of subatomic stories. ❤️
I am certain that I would like to see a massive number of your videos coming forever, you have enough energy to do that !
... The ghost of Heisenberg
Thank you, Dr Lincoln! Like you, my earlier education experience provided “a less than helpful “ explanation of the Heisenberg Uncertainty. And I have still struggled with the details all of these years, especially if trying to describe it to someone else. NOW I feel that I have finally GOT it (at least more) cemented in my head! Thanks to you for taking the effort to help clear this difficult subject 😊 for All of us; great video.
What does it really mean to add the wavefunctions ? Are we combining the electrons?
What an intelligent and informative series this is. It is presented by an exceptional teacher! Thank you...
I love this series. A bit over my head, but every time I watch an episode I feel a little smarter for the bits I DO understand.
Cool....didn't know about the time/energy application of Heisenberg's Uncertainty Principle...I LOVE learning new (to me) aspects of scientific principles (and getting more accurate explanations)....Thank you!
I studied engineering in college decades ago, which made a video I watched on RUclips several years ago make the Uncertainty Principle click. It said the same thing you did, that the momentum and matter (i.e. position) waves are Fourier duals.
Nicely stated, Dr. Don. Very nice. Glad to see that the zombie cat wasn't even mentioned!
Wow - this makes the comments a few weeks ago about the mass of the W and Z bosons make SO much more sense! Thank you!
I love watching all these, but I'm an old man and I'd be lying if I said I understand all this stuff, but I think I kinda get some of it , so keep em coming please.....
I watch your videos whenever I get the chance and all I can say is --Thanks! I guess I was lucky and got a decent understanding of the Heisenberg Uncertainty principle from my Prof's but I have to admit yours offered a nice, short, and concise conceptualization.
these videos are actually amazing for deeper knowledge for a level physics highly recommend!
That's awesome explanation for this principal
This is a quality episode. Keep up this extra level of explanation.
Finished your course on the great courses. Excellent. You are a great teacher!
For all who say ni
Buy them a shrubbery
I was sooooooo hoping that someone would say that.
Indeed.
Down chew poot very yubbles inta they aquasian?
Then it wouldn't be constant, would it?
Who the hell are you? We're the knights that say "nu".
embustero71 -sorry, crunchy frog excursion
Wow are you good at explaining things. I love your videos. Thanks from an old (OLD) guy and retired engineer!
Thanks for your videos, Dr Lincoln. I am anything but a physicist, but you have helped familiarize me with current thinking. I sincerely appreciate that. I have 2 questions (I apologize if they are stupid ones): 1. If I understand correctly (& please correct me if I am not), the galaxies are flying apart from one another not as objects flying outward from the original explosive Big Bang, but as a phenomenon of constantly expanding space pulling them apart. Yet you mention in this segment that matter and antimatter annihilated one another in the Big Bang at a rate of 3 billion particles of matter to 3 billion particles of antimatter (with 1 particle of matter left over for each 3 billion destroyed after contact with 3 billion particles of antimatter). Shouldn't this massive matter/antimatter contact have created an unimaginably powerful explosion, that Big Bang which would explain the spread of all matter outward from the point of the original singularity?; 2. Does that combination of 6 billion particles of matter + antimatter whose annihilating contact left over 1 particle each of the matter that comprises the universe today indicate that at the instant the Big Bang happened, the mass of the universe (in the singularity) was almost infinitely greater than what has been left over in the universe as we know it? Is there enough radiation in the Cosmic Microwave Background to account for all the Gamma Rays released in an explosion of such incredible size?
I love it when Don uploads
That's what she said.
Excellent. Thank you.
--------------------
For me personally modern physics & its vastly developed fields are important for curbing aside all forms of anthropic misconcepts of the post Aristotle periods.
And Heisenberg's Uncertainty, although at Quantum levels, but it also reminds us of indeterminism in evolutionary history, which many branches of different human hybrids have falsely treated with certainty/ deterministically.
Enlightening!!! Great explanation!!! Amazing series... pls continue posting amazing videos... I have seldom come across such reliable and interesting source of correct explanation for such complex topics.
Keep up the great work Don. I love your series.
I would really apreciate it if you would make an entire Video about the CMB. I am curious to learn more about it.
Hey Dr. Don. In your response to the last question in this video you said that the CMB is due to the annihilation of matter with antimatter in the early universe. Some sources say that the CMB is caused by the (re!)combination of electrons with protons to form neutral hydrogen when the universe was about 300K years old. Do these 2 mechanisms (matter/anti-matter annihilation and electron/proton recombination) both contribute to the CMB? If so, are there two distince CMB signatures that reflect the different initial energies and origination times? Thanks as always for a very interesting series!
Yes Don - I’m really enjoying the series - Many Thanks
The best explanation i’v ever seen, easy to understand, thank you sir.
Another good one Doc ! Funny, I'm enjoying physics more now in my 70's then I did in university (slide rule generation). Take care.
I've always understood it as since having a wavelength and thus motion, there's necessarily a tradeoff between knowing how fast they're moving during a period of time, or where there were at a specific instance in time.
I sort of think of knowing the location exactly like looking at a picture of the particle. Yes, you can clearly see where it is when it's not moving.
Maybe this is a flawed intuition, in which case anyone should feel free to let me know what i got confused here. :)
Great content as always. Thank you so much Fermilab.
Well I'm a little clearer. I get the FFTs, used those in the past. So there's a trade off between positional and energy information. Certainly the analogy of hitting the particle with a photon is wrong but I suppose it's a place to start. Not one that my A-Level Chemistry teacher used, but I remember the first test we had in A-Level Chemistry and there was a very high uncertainty factor indeed. It was a brutal shock that made us realise just how much harder A-Level was than O-Level/GCSE (UK school examinations).
Lovely explanation, thank you. Please do continue this series.
At university (before the top quark had been discovered) I came up with the idea of gravity being the cause of all forces, which in turn gives rise to particles.
The idea is that space is moving (in 3 dimensions) and that movement causes areas of space to be both expanding AND collapsing.
Collapsing space accelerates towards the speed of light which results in tiny areas (points) of the field of moving space appearing "permanent".
That is, a particle is not an actual "thing" but an area of very fast moving space.
Hi Don. Why do we superimpose waves from multiple objects to create a wave function when we only want to know the position and momentum of one object? Once we superimpose the wave to create a wave function, out of all the objects which are contributing their wavelengths, how can we be sure the wave function that is the outcome helps us determine the position and momentum of the intended objects and not other objects?
Wow, this video tied together quite a few facts about quantum physics and the universe that I've heard before in independent contexts.
Probably answered in a previous video, but...
What happens as particles cool down near absolute zero? Don't their position and momentum both become more restricted and well known? (i.e. both become less uncertain at the same time?)
At absolute zero, there are so-called zero oscillations. They are exactly the size (energy) defined by the heissenberg uncertainty principle. For example, if you have an atom in a lattice (eg. crystal of ice), then each of those atom vibrates with the energy of hf/2 (planck's constant times frequency over two), which is the h/2 uncertainty defined by heissenberg. Then, even at zero kelvin, the atom oscillates (in 3D it would be 3hf/2, for three dimensions) around the equilibrium with an unknown direction of the oscillation (front-back, up-down, left-right or its combinations).
Edit: the correct term is zero-point oscillation in English, sorry for that.
That's awesome you use Wolfram Alpha
Dr. Don Lincoln,can we substitute position and momentum at the same time in Max Born`s equation?
Awesome series!! Thanks a lot for doing this and making physics understandable and approachable by anyone!! I used to live near Fermi lab and always wanted to visit. I hope I can one day! Brilliant!
Great timing, I was having trouble finding a good explanation of this!
I am frankly concerned and curious as to why this particular channel doesn't have a higher subscription rate. Its FermiLab folk!! Not some goober with a grasp of physics but no clout( yes that sort of thing counts in believability and school choices).
I've heard of this guy before I came across the channel.
Now I'm not saying the other lads aren't on the ball or inaccurate, hell some of their info was probably from FermiLab. I'm just saying history, pedigree, veracity means a lot. It's just human nature I suppose.
Anyway I read about1 Enrico Fermi in the 4th grade for kicks instead of sports. As a result I had a career, family, a measure of success somewhat larger then Max Planck's rather intriguing constant though I prefer the unredacted version just to terrorize students and new teachers.
I expect a more rarefied appeal from Utbes proudly jaded Higher Branch MatheAddicts.
Please excuse my waaaaay too stylized writing. I've not had coffee yet.
Hi Mr. Lincoln. -douglas
My thinking uncertainly exact! It doesn't get better than Fermilab and having someone that can reveal things without excessive "dumbing down" is great at the same time not throwing a blizzard of integrals that glaze my eyes over.
This is a great series. Thank you for the lectures Don. Defund science outreach never!
I am certain that I barely understand Heisenberg's principle, though I am convinced that physics is everything.
I am absolutely enjoying this series. Keep it up! Was your description of the uncertainty principle at all inspired by Prof. P Moriarty’s video on the subject?
Both are "inspired" by any actual textbook on QM.
Nope. Lincoln is more of a Sherlock Holmes guy.
But, more seriously, this is standard stuff to anybody who has studied it.
Hi, Dr. Lincoln. Thanks to you and the Fermilab team for putting this series together.
I have some quantum skeptic friends that aren't convinced by theory alone that the uncertainty principle is anything deeper than the observer effect. Is there any experimental evidence that discredits this idea?
@Dr Deuteron This is a theoretical argument, not the experimental evidence I'm looking for. Wavefunctions themselves are never observable, after all.
Dr. Lincoln, I LOVE looking at the books on your book shelf. I suggest Martin van Crevelds "supplying war" for a different way to look at warfare.
great series. so i was among the "uncertainty is just a human measurement deficit" crowd at first but by watching a lot of youtube videos by you, sabine hossenfelder, 3blue1brown and parth g, i arrived at the fourier transformation explanation by which physicists claim its a property of the universe. what still bugs me is the following:
if i understood correctly, the schrödinger equation, which all of this is based on, is itself just an assumption, a postulate. i heard even the most brilliant physicists claim that noone actually understands what it is, but as it produces valid predictions everyone just uses it.
so, however mathematically rigorous the deduction of the uncertainty principle being a fourier transform of solutions to the schrödinger equation may be, its still the mathematically rigorous deduction from an assumption. it sounds like quite the stretch to me to call that a "property of the universe", the foundation seems to be very shaky especially as there is still the damokles sword of gravity and general relativity not being unifiable with quantum theory, which makes errors or gaps in any of these theories highly likely. could you maybe elaborate on that, id love to understand more about the foundations that quantum mechanics (and general relatitivity and a theory of everything) stand on.
i also once heard, that there are alternatives to the schrödinger equation (by heisenberg) and that schrödingers proposal was used because it was "easier to use". is that correct and what are the details?
and a last, totally unrelated question: all calculations and equations are fine and dandy but they dont explain the mechanisms of how things work. example: equations and measurements confirm that the speed of light is measured the same by every observer regardless of their own movement (hope that phrases it somewhat correctly). but has anyone ever tried to work out a kind of mechanism by which that would be possible?
I have a similar question about quantum randomness. Some physicists say the universe is deterministic and the appearance of randomness is just our ignorance/uncertainty of the precise values. This video didn't mention randomness, but randomness is intimately related to some interpretations of the Heisenberg uncertainty principle, and a discussion of quantum randomness would be appreciated.
@Michael Bishop an equation does not describe a mechanism, it enables you to calculate the output of one and maybe gives you the contributing factors.
Given the explanation you used to describe the adding of wave functions, I would suggest to have included reference to Feynman's Path Integral.
I love these videos! Thanks for sharing. 👍
There's so much I still don't understand:
1) How does one even go about measuring the properties of particles?
2) What sort of readings would you get back if you tried to simultaneously determine the position and momentum of, say, an electron?
3) Given that measurements have to be taken sequentially, what does a 'simultaneous' measurement even mean?
4) Related to three: given how fast something like a photon or an electron moves through space, don't measurements of their position or momentum tell you where that particle was or how fast it was travelling however long ago you measured it, rather than what it's doing or where it is 'now'?
What properties of a particle are you trying to measure? It's mass, it's position, it's charge, it's kinetic energy? Different techniques are used to measure different things.
The uncertainty principle is technically not about measurement. To the best of our knowledge right now, things don't simultaneously have an exact position and an exact momentum at the same time. Because particles have a wave nature, if you finally do measure the exact position of a particle, say you have it run into something and you see exactly where it landed, you no longer have any information about its wavelength. That information is destroyed. The term is called the collapse of the wave function. Also, if you measure the wavelength of the particle, you really can't know exactly where the particle is. There are a lot of good videos about that. Look up the ones from 60 symbols about the Heisenberg insert new principal. Those are good.
It's difficult to understand and it's difficult to come up with exact analogies. Quantum stuff is just weird.
Other ways to measure properties of a particle... shoot a particle with a known speed through a magnetic field, you watch how much the particle curves. If it has a charge, you can take that length of that curve and the angle it's deflected and calculate the particles mass and then it's kinetic energy and things like that.
Keep studying and keep learning. Physics is fascinating, but it takes years to learn a lot of it because much of it is beyond our everyday experience.
@@dankuchar6821
its*
It is somewhat similar to producing beats in sound by mixing sound waves of different frequencies. Notice, I said similar, so don't take the analogy literally.
That being said, we can get a very rough idea of what is going on by examining beats in sound. Mixing sounds of different frequencies results in interference patterns that result in localized areas of maximum amplitude and areas of zero or close to zero amplitude, so the waves are localized, and deliver their energies in bursts (beats).
The whole live cat dead cat existing simultaneously scenario in the Schrodinger's Cat story was originally meant to be a derisive commentary on the absurdity of quantum mechanics. Somehow it morphed into an accepted explanation. Just as the term 'Big Bang' was a derisive term at first and was somehow adopted by the physics community as an acceptable term, even though there was no bang as erroneously depicted in so many science videos.
Bumper sticker seen on a physics prof's door: "Heisenberg may have slept here!"
If the 'space' in the universe is expanding, do the particles and the fields they interact with also expand? In other words does a quark, neutrino, or any particle's waveform also get stretched out? Or does their size remain constant and they just inhabit more 'space'?
@Dr Deuteron I guess what I'm thinking is if the universe is expanding, and EVERYTHING scaled at the same rate, we wouldn't even see that expansion. So if subatomic particles are wave forms within fields, why don't they also 'expand' along with the space they inhabit? (I'm probably not explaining this very well.)
@@aaronnatera3685 it's not that space is getting less dense as it expands, when it expands it essentially generates new space with it's own vacuum energy. This is the only way to get the exponential expansion we see, if space scaled then even with vacuum energy the expansion would be linear.
Yes, particles also get stretched, this is exactly why the cosmic microwave background radiation today has such a long wavelength, corresponding to very low temperature, while it was born with much more energy (and shorter wavelength) corresponding to much higher temperature.
Thanks for all the replys. I think understanding the answer. Basically 'new' space is added, (along with its vacuum energy), but nothing 'new' is being added to the various fields that produce particles. They simply inhabit and travel through more space than before. Correct?
Everything gets stretched, including particles, but the forces holding particles together is greater than the expansion of the universe, so their size doesn't change. And if it did change, the amount would be a measurably tiny, and as I understand, it's smaller than the Heisenberg uncertainty principle would allow us to even come close to measuring.
That's an insightful question. Good job!
Hi Mr Don.
what sizes do elementary particles have?
For example, the electron is considered as point like particle, but, if it is pointlike, then it should be a black hole, which in turn should evaporate quickly.
So, electron is considered pointlike because we cannot measure size, or, it really does not have any length?
I love the Questions ! Its super entertaining. Please keep it up?
There's a 3Blue1Brown (math-animation&explanation) video about the uncertainty principle, and where it shows up both inside and outside of physics: "The more general uncertainty priniciple, beyond quantum"
Wow, what a great video and series! Much thanks :)
In your answer to the question about matter-antimatter annihilation, it was asked where the energy went and your answer was the CMB. I thought the CMB was for the big bang, not the annihilation energy? Are these linked or independent sources of CMB?
Well for the first ~380000 years the universe wasn't transparent (like a star is not transparent), so the CMB is radiation produced at that later period when it finally became transparent. Not quite the early stages of the big bang.
I'm not sure it's been said, but I've always thought a good way to explain it to people who don't get it is to imagine taking a picture of a bright yellow/green tennis ball, thrown in no specific direction in a clear blue sky. The more crisp the picture, the less information you have on the direction/momentum of travel. However, if you get the blurr effect of movement, you get a more accurate indication of those measurements, but less information on its exact location.
I'm not sure how accurate that is? But it always made sense in my head, at least.
Wow, this video did me better than the entire course of physics in my college.
Hi Don! Is Heisenberg uncertainty principle equally valid for virtual particles as it is for subatomic particles?
They are described by same kind of waves so they have the same mathematical properties regarding this uncertainty. What they differ in, is the mass-energy-momentum ratio, they don't have to be "on the mass shell".
@@thedeemon woah, that's very interesting. Thank you sir 😄
Dear Don,
On the question about neutrinos penetrating a neutron star, you talk about a low energy muon-neutrino turning into a muon and a low energy electron-neutrino interacting with a proton, turning it into a neutron. Please elaborate on that, as (in the latter case) I thought it takes at least an electron (also) (with a very much defined energy as you previously stated) to turn a proton into a neutron (conservation of charge).
Or have you forgotten to mention something?
hey D.lincoln i want to ask u about the Axion particle and if it is maybe the answer for the missing antimatter in the universe
Dr. Lincoln great episode+ Thank you so much :)
In a previous video you talked about how mass actually doesn't increase when velocity reaches relativistic speeds. Could you please explain that a little bit?
Wow
Great work
Keep it up Sir
I've run out of Fermi lab videos to binge watch during quarantine. Pls help
There are more science channels to the rescue:
Sci Show / Microcosmos (general popular science)
Kurzgesagt (scientific stuff with a moral)
Launchpad Astronomy (accurate science facts on astronomy)
PBS Spacetime (specialized science, math free)
Isaac Arthur (science and speculation on the future of humanity)
Many of Brady Haran's videos with the University of Nottingham
Royal Institution (recorded public lectures)
Anton Petrov (astrophysics papers summarized)
Dr Lincoln thank you for your fascinating video series. I have been puzzled since high school at the extremely uniform masses of the electron and proton. You have made the mass uniformity of the electron perfectly clear. However I have learned from your videos that the internal mechanisms of the proton are very complex. Is the proton mass as equally uniform from proton to proton as the electron?
Yes.
I understood some of this so I have a bit of a better understanding which is cool. I still have a long way to go. Thanks for getting me just a little bit further :)
Is it actually necessary to use particles to describe "particle physics" at all, or could we just say that everything is waves in fields and not resort to particles at all?
Sir, I think I have another valid argument against this observer effect! I would like to know your opinion on my argument if you deem it fit and sensible enough to reply because I might be wrong and even foolish here :) This observer effect of using light to determine position of electron with a simultaneously change in electron's momentum is not Heisenberg uncertainty principle because this will only produce RANDOM scattering of electrons on the other side of the slit in the famous double slit experiment and NOT the proper INTERFERENCE pattern which we usually see! This observer effect cant produce observed interference pattern but only random non-interference pattern on the screen as seen in the case of wave-particle duality of matter.... So, we should not confuse Heisenberg Uncertainty principle with observer effect .... Am I right or wrong ? I would like to know your answer ....
I understand the momentum and matter waves, and that the Uncertainty Principle means they’re Fourier duals. But for the alternative form of energy vs time, what are the physical interpretations of the “energy wave” and “time wave” (functions)?
Hi doctor...
since the universe is expanding in an accelerating rate, will the rate of expansion exceed the speed of light?
It already does: many galaxies we see are currently receding faster than light. Hubble law for the expansion says every second all large distances get multiplied by a constant k. It means you can always find a distance L such that it in one second it increases more than light goes in one second: ktL - L > ct.
Also, that's why you sometimes talk about the "observable universe" - we cannot see beyond, since the far parts are moving at more than several lightspeeds away from us. (why we can see things moving away more than one lightspeed fast would be a good topic for another video :) )
I have a specific example in mind: using laser we send single photons threw a hole (the size of the photon) into a detector. We know exactly the energy (frequency) of every photon, their speed (c) and we know that if the photons were detected, they must have been in a specific location (they went threw the hole). In short: we know everything about the particle in one moment of it's life. Can someone please explain to me, why this example doesn't break the Heisenberg's Uncertainty Principle? Thank you in advance.
A photon is wave, not a particle, while it is alive. It doesn’t have a definite position until it is measured, which is when it dies. The best you could do is send a single wave pulse of a specific energy through the hole. It's not clear to me what the size of a photon would be either. It's wavelength? It has no height or width.
In one episode of ST:TNG there was a "Heisenberg compensator". Which worked around the problems caused by the Heisenberg Uncertainty Principle, allowing the transporter sensors to compensate for their inability to determine both the position and momentum of the target particles to the same degree of accuracy. This ensured the matter stream remained coherent during transport, and no data was lost. How can that thing be built?
You and Matt are the best - thanks much
Another great video! Thanks for sharing!
Thank you Sir at last after long time now understand what is Heisenberg uncertainty principle. I need a clarification, can Heisenberg uncertainty principle address teleportation from quantum level to molecular level, like predicting velocity of an moving object and relative velocity required by the mass to travel along with predicting the position of objects moving in a path
Can you please make a video on invisible quark, because I can't find a good explanation of it on the internet.