Some people in the comments are prospective physics majors and I just want to make something clear: this video is a joke/exaggeration. Usually you spend months or years building up to the more complicated physics concepts. And a good prof should never make fun of you for getting an answer wrong. Also, while you may feel dumb at various points in university, I can guarantee your classmates will feel the exact same, so it's a journey you'll be on together. That said, I think many engineering/physics majors (myself included) can relate to the feeling of spending hours trying to understand something, and still not fully "getting" it. It happens. That's the feeling I'm trying to make fun of here. But it's a normal part of learning and I wouldn't let it discourage you. I've made nearly 80 physics/math videos on this channel and I wouldn't have done that if I didn't enjoy physics!
Ah, you're CURRENTLY in the void? Me I managed to escape. Don't worry, one day I will free my breatherin, and we will one day destroy momentum once and for- Ah shoot, the avengers are on me, gotta go!
And also when you first learn about complex numbers after thinking that √-1 was invalid and does not exist. Its like realizing you didn't know about an entire planet.
@@maxwellsequation4887 who told you imaginary numbers don't exist? They do exist on the complex plane. Their name is what makes people think they're not "real"
I sent a letter to Dr Feynman when I was a student in a QED class. He actually answered me. I was trying to make sense of mechanism of particles attracting each other since my "physical" picture could explain how they could repel each other. What he told me applies here. All our theories are simply model for the actual universe. If the model give you a result that works, it is a good enough model to use. Therefore, if Momentum equals Mass times velocity works, use it. If not try one of the other models. This same principle applies to all our theories. It's why we can use Newton's equations most of the time and get good answers.
@@xiupsilon876 Maybe. What I do know is that my stepfather, a physiologist living in Australia, wrote to Feynman and he received a two page letter in reply. Feynman was apparently very gracious like that.
@@davidhildebrandt7812 I'm just making fun of the fact that a lot of students don't take physics or drop out of the program quickly (at least as freshman). I know it's *possible* that there can be hundreds of students in one class that discusses the inertia tensor. The joke is that (at least I really expect) it to be very uncommon, i.e., upper div physics ain't that popular among the general college student.
Leonhard Richter I’m referring to people quitting as freshmen. Inertia tensor is first semester during (i would imagine often) third year. i doubt many people drop the major at that point, BUT i have no data ¯\_(ツ)_/¯
It's not any better in the social sciences btw. In fact, it might actually be worse. Normal, everyday words become increasingly unfathomable the more theorists' musings about them you read.
Unless you are in Soviet Russia. There is a series of books there called "Physics for Everyone!". One of the books is titled "Experimental advancements in the measurements of the Universal Constants."
I love this academic humour thing. I studied computer science (defending my master's thesis tomorrow) and I felt soooo lost first semester. They were like "No programming background required", so I thought I were ahead already knowing basic programming when I started.... Then they slapped me with linear algebra, set theory, advanced logic, etc. and I realised why programming wasn't a pre-requisite. Programming is a tool for computer science; It isn't computer science itself
@@eigenchris I am 300 pages deep in a book about angular momentum algebra. Like Wigner D functions, Clebsch Gordon coefficients and shit like that. Feel like i'm about to push that button any day now, my head is smoking.
Addition to the end: Not knowing if you should use the inertia tensor or relativity or linear momentum, you treat your entire mass as a single point particle. This will surely allow you to use linear momentum and you can recapture your childhood pride. You work hard to figure out your position and measure the time change so you can find your velocity. But as soon as you figure out where you are, Heisenberg shows up and slaps you in the face.
Sorry to hear. I think all physics students have been there. There's one quote I like which says "All physics is either impossible or trivial. Physics is impossible, until you understand it, and then it is trivial." Hope things start making sense soon.
@@eigenchris Thank you. Really. I've just been watching through your tensor series. I'm trying my best to follow since it's less than a month before my exam which I'm taking for the second time. Thank you for your efforts.
This reminds me of one of my more embarrassing moments in undergrad. I spent hours scouring the index of my Quantum Mechanics textbook, confused why I couldn't find the word "momentum" anywhere. And then I realized I was looking under the p's and not the m's.
I have never related to a video so much as this one. But seeing how good you are at your videos gives me the motivation to grind through the absurdities of physics, even if I've lost hope of understanding it really well as I thought I did in school.
I'm glad you like my stuff. Most of the "insights" in my videos didn't come to me from grinding through homework problems. It's mostly lots and lots of googling, searching for the best possible explanations, and spending lots of time thinking about how to make things simple. It's definitely not the way school is set up.
@@eigenchris Yeah, it isn't, which is infuriating tbh. They want students to get good grades and learn and yet teach in the worst possible way I can think of. Especially mathematics, instead of giving a problem and then solving it and then generalising, it's in reverse, first a theorem out of nowhere, then a boring proof and FINALLY the example, which is the most important part. The species that was smart enough to discover ways of mathematically describing general relativity and quantum mechanics is the same species stupid enough to not be able to create a good, adaptable education system.
@@momchi98 Yeah, exactly. To me, it seems like a definition should be something you introduce after 20-30 minutes of giving examples and motivation... otherwise you have no idea why the definition matters. The math/physics TH-camr Tibees did a video called "A Mathematician's Lament" where she talks about this problem. She quotes an essay that says the problem with math education is that "questions are asked and answered at the same time". I find the definition/theorem/proof style of exposition unreadable a lot of the time.
@@eigenchris so the anger to destroy momentum gave rise to the momentum that became Eigenchris and certainly a motivation for thousands, many of whom will spread your legacy in the future...
For me, momentum is the conservation quantity that follows from space translation invariance. The thing with the inertia tensor is not momentum but angular momentum and this is the conversation quantity that follows from rotational transformation invariance. One should grasp the Noether theorem as a fundamental theorem of physics that defines plenty of quantities.
@@bayleev7494 Well, if you assume that certain symmetries occur in a system you can derive expressions for conserved quantities (according to Noether). No one prevents you from calculating these expressions if the symmetries no longer hold true. Let's take a look at an example. Let's say we have a simple mechanical one particle system that obeys the laws of Newton. The whole system can be described by finding a proper Lagrangian L that depends on the position and velocity of the particle at all times. Let's assume the system is time translation invariant. It follows the following conserved quantity according to Noether. E=dL/dv*v-L where v is the velocity of the particle. This quantity we call energy. Now you can let act a time-dependent field on the particle. In that case the symmetrie hold no longer true (and energy is no longer conserved) but you can still calculate the expression dL/dv*v-L and say that this is the energy of the system at any given time as long as you know the Lagrangian L of the system. Does it make clear?
This video actually makes a good point about how physics is taught. A subject like math is built from the ground up with a rigorous framework, but physicists just write formulas without proper definitions and have an expectation that no one will actually understand anything. Someone famous said "No one really understands quantum mechanics." Can you imagine saying that about any math field? "No one really understands number theory." "No one really understands algebraic geometry." No, that would be ridiculous, since these are fields that are built in a rigorous framework with proper definitions, and the people who study them actually understand them.
As far as I know, standard quantum mechanics (not venturing into quantum field theory) does have a rigorous formulation. The confusing stuff comes more from the physics, like entanglement and probabilistic measurements.
@@eigenchris what does energy operator and moment operator operating on a wave function actually means? If wave function represent the wave, what is the logic behind to use the product with its conjugate as the probability of particle, apart from after some calculation, it seems it matches our measurement? If the product represents the probablity wave, shouldn't we actually apply operator on the product instead of the wave function itself? Any logical justification for throwing Imaginary part away or multiple the conjugate in order to obtain a real number? When reading quantum mechanics, often i felt, it seems follow these math steps and the calculation gives a good result that closely matches experiment. however, each of these calculation steps does not make much sense, or at least, not well explained and too hard for me to understand.
I discovered your Tensor for Beginners series googling what a Tensor is, and I end up studying special relativity, hypnotised by your reasoning. I want to point that you only require from your audience basic matrix multiplication. I think this is the first time in my life that I have met a living genius.
I'm so glad this video found me. Struggling through my PhD in mechanical engineering right now, ans the amount of times someone has said "well actually, its more like this..." to me is unbelievable.
I once thought about this while being in high school (currently a Physics major) that momentum is a clever combination of mass and velocity that gives you an idea about the impact when two bodies collide. Well you were true that momentum is generalised to a very complex level in current theories of Physics but foundationally there is no meaning to momentum if we are studying just a single particle. When two or more particles interact, they do require some kind of a defining quantity that has information about their respective inertia and the motion they have. Momentum is trying to give you an information about how much mass changes its position in unit time. Still my explanation lacks the clarity it should.... Lets try a bit more and figure it out.
Newton referred to it as the "quantity of motion". A measure of how much motion or movement occurs. It increases with mass because more matter preformes movement and increases with velocity since the same mass literally moves more 😁 That's how I think of it intuitively.
2:58 Probabilities are just the square root of the 'momentum operator'. That's why there's an "i" there. The momentum operator works strictly on the plane perpendicular to the Real numbers too, hence why it's imaginary 😶.
Captain America giving me a motivational speech but then getting me arrested anyways was *very* heartbreaking. Not to mention the fact that Tony could have just chosen to explain momentum to me instead of eating shawarma after throwing me into a frictionless vacuum chamber (I feel like he specifically designed that too)
This video is an exaggeration. Usually you work up to these concepts slowly, over the course of months or years. And a good prof should never make fun of you for getting an answer wrong. But the feeling of not knowing what momentum is anymore after finishing a physics degree is kinda true, at least for me (particularly in quantum). I hope you enjoy your major and have fun, even if it will be confusing sometimes!
@@maxwellsequation4887 Yes, but the theories are increasingly more mathematically abstract and get separated away from your normal intuitions about the usual flat 3 dimensional space with objects obeying newtons laws.
Supposedly a joke video, yet I found this to be one of the most informative and educational physics videos I've ever seen. Very condensed way to present a lot of ideas. Excellent work.
1:31 in our country's highschool you actually do this. But none of these inertia tensor crap, you just memorize the moment of inertia formulas for a bunch of shapes like sphere, cylinder, rod etc.
@@unnikrishnanvr186 yeah I know. I didn't mean to imply that our highschools were in a higher level, just that we did a simpler version of it, in university you learn the derivation of those formulas and much much more
I feel like this a lot. I remember when gravitational waves were first discovered. In excitement I rushed to wikipedia and quickly found the GW page. Eagerly, I read the first paragraph. There were 11 words with links. I didn't know what any of them meant. I just had to laugh so that I wouldn't cry. Thanks for doing what you do to make the world a little less inscrutable. I'm looking forward to your Tensor playlists. I've gotta build up the maths first though. Cheers!
I feel your pain. I remember when I had an assignment due the next morning and needed to calculate some line integrals, but I had absolutely no idea how to do that or what that even meant. This feeling of being too stupid built up the whole semester prior until it reached this "grand finale" the moment I failed the very first assignment of the semester. I was honestly just devastated that it had come to this. Maybe I shouldn't have, but I quit right then and there and never visited another lecture. Sounds kind of irrational when I explain it like that, but believe me when I say I never felt so stupid in my entire life. I'm in electrical engineering now and I feel a lot better, but videos like this help me get over this horrible experience still lingering in the back of my mind. We all experience hardship. We are not too stupid, no one is. And when we feel like we failed, we should get back up, brush the dust off our shoulders and try again, because that's all we can do.
This is accurate. High school only teaches us about magnitudes and gives no context to what velocity and acceleration are. Later you learn about Multivariable Calculus and that velocity is dr/dt, where r is a vector. Acceleration is d^2r/dt^2. That is when it makes sense. The reason why high school never gives context to acceleration and velocity is to hide the hard truth.
I don't think they are intentionally trying to hide the truth. They are just presenting a limited scope of the truth, at a level that is reasonable for a class of high school students to understand. And not having the background of calculus available, really limits the amount you can teach at a high school level, as you are limited to the special case of constant acceleration. For the same reason that a elementary school teacher tells you that you can't subtract 3 from 2. I think most teachers of any grade level know about negative numbers, and would tell you about them if you asked about them outside of class. It's just not relevant to the scope of the class they are trying to teach, and you are far beyond the intended lesson that you'll just end up confusing yourself and others, if you insist on introducing negative numbers before you master subtraction in the purely positive case.
@@carultch Wait what? In my high school, you learned calculus in physics class because you needed it, and the calculus class was still trying to teach limits, and only gave up and taught calculus later on.
@@psychohist I can't speak for every high school. This is based on my experience. Your experience may be different. Calculus is usually a senior-level subject in high school, or a college subject, so if you're trying to teach a physics class much earlier than that, you'll have to abridge it to work with the background the students likely have. You certainly aren't learning detailed techniques of integration, like parts and partial fractions, to cover the basics. At most, you might learn a limited scope of calculus for the topic at hand. Such as the power rule, which I think most students can handle with just an algebra background. Easier to learn the power rule, than to memorize the formulas that came from it.
This is the most depressing April Fool's Day post EVER. But thanks for posting this. Will convince a lot of people that instead of Physics, you should major in Math!
The best part about it is that no one explained that they are the same thing!! P=mv applies in relativity under Lorentz transforms Iw=L is kinda like adding up all instantaneous momentum’s…so adding up lots of little p=mv’s And quantum physics…well…that’s another story haha But in Lagrangian mechanics the Lagrangian is defined in terms of potentials, of which the time derivative can be thought of as like a change in force ie change in momentum Boom…it all makes sense. All you need is p=mv Might’ve explained Lagrangian wrong but oh well I’m just as confused as the next guy idk how I made it this far
Okay my friend is this was amazing. I'm sure all of your physics courses are really good but I'm telling you you should have a side channel in humor. You had me all the way along just laughing and enjoying the whole thing. This is a work of art
@@reckie1000 no, work is the integral of force TIMES VELOCITY. And Steven's right, since (as long as mass is constant), F = ma = mdv/dt = d(mv)/dt = dp/dt, so p = Integral of F dt.
@@reckie1000 Depends on what the variable of integration is. When the variable of integration is position, that's work. When the variable of integration is time, that is impulse, and impulse becomes a change in momentum.
@@deltalima6703 One difference is the units. Time and distance might have the same units in Planck units, but not in the units familiar to us. Another difference is that the variable of integration for work, needs to consider all possible directions in space, and so it is really a dot product line integral, rather than a simple integral relative to the variable of integration. For integrating relative to time, the direction is implied to be in the axis of the dimension of time, no matter what, and forces are never directed in that direction. You can think of impulse as a hidden cross product, because it is a multiplication of two vectors that are guaranteed to be perpendicular. Though you don't need to think about cross products, because time is ordinarily treated as a scalar. Perhaps there is a unification of work and impulse in general relativity that makes use of the generalized 4-velocity and tensor calculus, but I haven't explored it.
Based on many true stories!!! Lol, that was so funny, and still being in high school I learned about momentum only this year (12), and I cannot believe after 12 years in school I'm nowhere career-wise and knowledge-wise on any topic... The worst is the time pressure for sure...
Well you've now got the foundations, and should be able to add any skyscrapers of focused knowledge you could need for the future career(s) you'll decide to embark on.
I got my bachelor’s degree in Physics with flying colors. I still rely on the solution manual whenever my juniors ask help for their problem sets. Plus, I’m in a constant love-hate relationship with Physics. 🤣
I thought I had a hunch what momentum was some time back in the late 90’s. I told a momentum obsessed friend about my hunch. He said I was wrong. The hunch never left me. Now I know I was indeed wrong. Thank you. 🤓 Edit: he was an engineer, by the way, so he was probably wrong too. That gives me some kind of comfort. Now I can finally start living my life.
When you realize that in an elm field qA adds up to mv so that the momentum was a disguise for the impulsion, so you look for further explanation and you find this video telling about ur life
It gets even worse when mixing languages... My first language uses impuls for momentum, but still says moment(um) to torque. And then angular momentum is 'impulsmoment'. -_-
@@mikhailmikhailov8781 In Spanish it's just a literal translation of the English terms. Angular momentum - momento angular Linear momentum - momento lineal But Moment of inertia - momento de inercia Moment of force - momento de fuerza Spanish language Wikipedia uses the terms "cantidad de movimiento" (quantity of movement) and "ímpetu" (impetus) as synonyms for momentum, even though I've never seen those terms in Physics textbooks.
This video made me laugh several times haha. While somewhat dark, this video reminds me of when I got my B.S.E. in Engineering Physics and now getting my PhD in Biomedical Engineering (though my work focuses on continuum mechanics of soft tissues and I continue to learn advanced E&M, QM, and GR on my own). There's always a more generalized definition lol. Really well done
Man, I think I laughed a little bit too hard on this one 😂. I saw this somewhere else and I had to immediately come and subscribe. This is just so accurate, I’m in tears .
Very nice video. This applies to chemistry in general too. It goes from being just a memorized operation with cool breaking bad font letters that have dots around theme and unique properties, to then truly getting that theyre bonding atoms that make up everything, to then learning how the bonds and molecules work, and then getting that whole paradigm shattered by learning about electron orbit clouds making the previous images you had in mind a joke, and than you realize every bond and molecule is just loosely grouped and defined ways of protons neutrons and electrons interacting. AND THEN you learn about quarks and quantum physics and you realize the thing youve been learning about basically does not exist and is just a way for us to describe physics on a more macro scale (ironically the most micro things people think of, atoms and molecules) And then you might stumble across string theory and realize even those quantum fluctuations are not base reality. The rabbit hole truly never ends, i guess momentum is the rabbit in this case
In India we learn this stuff in high school to crack exams like Jee, Neet, Cet, etc. I can feel your pain bro This education system is killing my curiosity. I am not the same kid as I used to be when I was a child. I was always curious to know how things worked and I used to learn them with interest. But bow as I am in grade 11th I have a pressure of clearing Jee advanced and get into an IIT or other good college to become a robot 🤖 and work in an boring company.
Dude I feel you. I don't know if it would help but there is a TH-cam channel called flipping physics which has a jee playlist. He helps more visually to get the idea but if you ask me, momentum is some kind of impact or smth
Eigenchris this was amazing! I hope to survive in my general physics class next week which is unlikely because I´m in a way to early phase of my studys. But with your channel I still have a chance!! Greetings from Germany.
What about the variation of the action with respect to varying the spatial coordinates of the endpoint? Huh? Huh? Come to think of it, though, isn't the real momentum the friends we made along the way?
3:54 Me in college, knowing that momentum isn't ρ=mv but I can't write that otherwise I'll fail the class 😝. Not like it matters either, we're not studying contexts where it's relevant to use another more precise formula 🤷♂️.
This was not a joke really. You brought out the confusion in Physics wonderfully. If you think about it, most of the ideas presented to us in high-school and college (and beyond) is sort of doled out by an authority. So p = m*v is just a formula to be memorized and you don't get to question why is the product of mass and velocity a special quantity? You have to just follow (or else you are a bad student of science, and will be dropped from further science education). Even Einstein did not have a clear understanding (nor does anybody else) as to why "inertial mass" (which features in Newtons law F = m*a) is identical to gravitational mass (which features in weight = m * g), so he simply put it as an axiom in his general theory of relativity. Ask even those scientists working at CERN - "what is mass?" and even they will look confused. Our science education is really very shaky and indulges in a belief system. We hope this changes, hopefully soon.
Some people in the comments are prospective physics majors and I just want to make something clear: this video is a joke/exaggeration.
Usually you spend months or years building up to the more complicated physics concepts. And a good prof should never make fun of you for getting an answer wrong. Also, while you may feel dumb at various points in university, I can guarantee your classmates will feel the exact same, so it's a journey you'll be on together.
That said, I think many engineering/physics majors (myself included) can relate to the feeling of spending hours trying to understand something, and still not fully "getting" it. It happens. That's the feeling I'm trying to make fun of here. But it's a normal part of learning and I wouldn't let it discourage you. I've made nearly 80 physics/math videos on this channel and I wouldn't have done that if I didn't enjoy physics!
+
Thank you for existing dude
its almost as if you put joke in the title. The nerve of these haters man..
I needed this.
Jokes on you we went straight to the sauce. (Jk, taking a physics graduate study with an engineering undergraduate degree is a joke) I'm the joke
I have a masters in physics and I can say this is 100% accurate, I'm currently in the frictionless void myself
So did you meet Avengers. Or DC HEROES came to capture you
@@yashkrishnatery9082 no that only happens to engineers
@@yashkrishnatery9082 It was actually the Teenage Mutant Ninja Turtles for me... weird.
Ah, you're CURRENTLY in the void? Me I managed to escape. Don't worry, one day I will free my breatherin, and we will one day destroy momentum once and for-
Ah shoot, the avengers are on me, gotta go!
for me it was shaktiman and doremon....weird indeed!
This had no right being this good. The teacher’s sad eyes broke me. Brilliant story telling
well my physics teacher was the most enthusiastic one of all of the teachers
The jump from High School physics to undergrad and then grad school is the ultimate "Those bastards lied to me" story
lmao being someone with a degree in physics, I felt that.
And also when you first learn about complex numbers after thinking that √-1 was invalid and does not exist. Its like realizing you didn't know about an entire planet.
@@maxwellsequation4887 who told you imaginary numbers don't exist? They do exist on the complex plane. Their name is what makes people think they're not "real"
@@Thanos-hp1mwSome teachers say √-1 is invalid as a shortcut to avoid answering questions
I joined my undergraduate programme in physics few weeks late, first class i attended was on tensors. i immediately felt this line. XD
As a recent physics grad and current high school physics teacher, this resonated on levels I can't begin to explain.
Those little dummies, they never see the dark side until its too late... Muahahahaaaa
Sounds like you've lost your momentum in your learning journey.
@@fillfreakin2245bs dum tss
@@fillfreakin2245 😂😂
This is how it feels for any science subject when you go to university/college. Exactly how it was for me with Maths.
I sent a letter to Dr Feynman when I was a student in a QED class. He actually answered me. I was trying to make sense of mechanism of particles attracting each other since my "physical" picture could explain how they could repel each other. What he told me applies here. All our theories are simply model for the actual universe. If the model give you a result that works, it is a good enough model to use. Therefore, if Momentum equals Mass times velocity works, use it. If not try one of the other models. This same principle applies to all our theories. It's why we can use Newton's equations most of the time and get good answers.
Agreed
What an amazing story! Do you still have your letter? Did he say anything else?
I sense bs
I now officially love you! Thank you!
@@xiupsilon876 Maybe. What I do know is that my stepfather, a physiologist living in Australia, wrote to Feynman and he received a two page letter in reply. Feynman was apparently very gracious like that.
The biggest joke is that there are 300 people in one class learning about the inertia tensor
This is true 😂
Why? Just a few weeks ago I was in a (digital, but normally it wouldn't be) uni lecture with about 400 ppl learning about the inertia tensor
@@davidhildebrandt7812 I'm just making fun of the fact that a lot of students don't take physics or drop out of the program quickly (at least as freshman). I know it's *possible* that there can be hundreds of students in one class that discusses the inertia tensor. The joke is that (at least I really expect) it to be very uncommon, i.e., upper div physics ain't that popular among the general college student.
@@4001Jester Well but this would be somewhere in the first semester when not so many have quit yet
Leonhard Richter I’m referring to people quitting as freshmen. Inertia tensor is first semester during (i would imagine often) third year. i doubt many people drop the major at that point, BUT i have no data ¯\_(ツ)_/¯
This is what it feels like when you go from popular science books to textbooks.
Lol
So true
Or from elementary school to high school.
"No Bobby, you can't take 4 from 3."
"Ms Grindlefarb _lied_ to me!"
It's not any better in the social sciences btw. In fact, it might actually be worse. Normal, everyday words become increasingly unfathomable the more theorists' musings about them you read.
Unless you are in Soviet Russia. There is a series of books there called "Physics for Everyone!". One of the books is titled "Experimental advancements in the measurements of the Universal Constants."
I love this academic humour thing. I studied computer science (defending my master's thesis tomorrow) and I felt soooo lost first semester. They were like "No programming background required", so I thought I were ahead already knowing basic programming when I started.... Then they slapped me with linear algebra, set theory, advanced logic, etc. and I realised why programming wasn't a pre-requisite. Programming is a tool for computer science; It isn't computer science itself
Computer science is no more about computers than astronomy is about telescopes.
- Edsger Dijkstra
BRUH, U REALIZED THIS NOW??????
This video got super real for a few minutes and then violently pulled me back into the joke
Feynman: I think I can safely say nobody understands Quantum mechanics.
Eigenchris: I think I can safely say nobody understands Physics.
This is even more deeper than feynman's line about QM, here Eigen is demonstrating human's limitation against God's architecture (planned/unplanned).
@@AntiGroup you forgot to say: assuming god exists*
@@batuhankoyuncu1336 I think everyone has their own meaning to the word God, I like to use it often to represent Universe and something beyond.
@@AntiGroup, I am atheist but all I
can do is like your comment
@@truthseeker7815 I appreciate it.
I keep coming back to this video after learning more physics and see the progress I’ve made
Eventually you will reach the "destroy the universe" stage, so be careful there.
@@eigenchris I am 300 pages deep in a book about angular momentum algebra. Like Wigner D functions, Clebsch Gordon coefficients and shit like that. Feel like i'm about to push that button any day now, my head is smoking.
@@joda7697 Sounds like Zettili ... Is it?
I do the exact same lmao
Stick with it. Eventually, you will get the real answer - 42.
Addition to the end:
Not knowing if you should use the inertia tensor or relativity or linear momentum, you treat your entire mass as a single point particle. This will surely allow you to use linear momentum and you can recapture your childhood pride. You work hard to figure out your position and measure the time change so you can find your velocity. But as soon as you figure out where you are, Heisenberg shows up and slaps you in the face.
🤣🤣🤣🤣🤣
If you remove the last line it can become the good ending.
Heisenberg be like: Yall aint measuring anything fools
Hes not a quantum particle so his momentum is not probabilistic
Man fxck Heisenberg ! 😅
"Speedy thing goes in, speedy thing comes out" -self aware killer robot
I'm eternally bouncing in a void with perfectly elastic collision.
Word
"Life is pointless and physics will never make sense no matter how hard you try to understand it" is my current mood.
Sorry to hear. I think all physics students have been there. There's one quote I like which says "All physics is either impossible or trivial. Physics is impossible, until you understand it, and then it is trivial." Hope things start making sense soon.
@@eigenchris Thank you. Really. I've just been watching through your tensor series. I'm trying my best to follow since it's less than a month before my exam which I'm taking for the second time. Thank you for your efforts.
Unless you treat it as a point mass, then it isn't pointless...
Alright I'll see myself out. :P
@@mcalkis5771 how is it going?
@@pepaxxxsvinka3379 It's going much better actually. My studies are actually starting to pick up pace and I'm passing my classes.
No one:
Physics: *Momentum* can be whatever I want
Entropy: hold my beer
This reminds me of one of my more embarrassing moments in undergrad. I spent hours scouring the index of my Quantum Mechanics textbook, confused why I couldn't find the word "momentum" anywhere.
And then I realized I was looking under the p's and not the m's.
pomentum
I mean p=mv
popentup
At least you gave p’s a chance.
A like for an unexpectedly funny pun.
0:22 I start to realize that something not right in this video at this moment.
"Momentum, a function of mass and velocity, is conserved between portals. In layman's terms, speedy thing goes in, speedy thing comes out."
- GLaDOS.
Very in-character for GLaDOS to lie to you like that lol
This was a triumph.
I'm making a note here
Huge success
This is a physicist's fever dream.
Also known as a Boltzmann brain
I think this is more like a physicist's life
nightmare*
Man, that story got depressing very quickly. The man had a teen, early-mid, mid, and late mid-life crisis and Tony just wanted a Shawarma.
What's sad is the fact that this dude never figured out momentum calculations while Tony could do it in his sleep.
@@spinyslasher6586 Tony stark was prolly laughing at him for how much of a dumb idiot he was.
I, too, want a Shwarma. Been four years since I've had one.
@@maxwellsequation4887 "When did you figure out how to calculate momentum?"
"Last night."
I mean shawarma is so good ...
You can't blame him
(I eat shawarma once every 2 weeks lol)
I have never related to a video so much as this one. But seeing how good you are at your videos gives me the motivation to grind through the absurdities of physics, even if I've lost hope of understanding it really well as I thought I did in school.
I'm glad you like my stuff. Most of the "insights" in my videos didn't come to me from grinding through homework problems. It's mostly lots and lots of googling, searching for the best possible explanations, and spending lots of time thinking about how to make things simple. It's definitely not the way school is set up.
@@eigenchris Yeah, it isn't, which is infuriating tbh. They want students to get good grades and learn and yet teach in the worst possible way I can think of. Especially mathematics, instead of giving a problem and then solving it and then generalising, it's in reverse, first a theorem out of nowhere, then a boring proof and FINALLY the example, which is the most important part. The species that was smart enough to discover ways of mathematically describing general relativity and quantum mechanics is the same species stupid enough to not be able to create a good, adaptable education system.
@@momchi98 Yeah, exactly. To me, it seems like a definition should be something you introduce after 20-30 minutes of giving examples and motivation... otherwise you have no idea why the definition matters. The math/physics TH-camr Tibees did a video called "A Mathematician's Lament" where she talks about this problem. She quotes an essay that says the problem with math education is that "questions are asked and answered at the same time". I find the definition/theorem/proof style of exposition unreadable a lot of the time.
@@eigenchris I think physics Professors should read your comments and I hope they will not search the secret universe destroying buttom afterwords.
@@eigenchris so the anger to destroy momentum gave rise to the momentum that became Eigenchris and certainly a motivation for thousands, many of whom will spread your legacy in the future...
For me, momentum is the conservation quantity that follows from space translation invariance. The thing with the inertia tensor is not momentum but angular momentum and this is the conversation quantity that follows from rotational transformation invariance. One should grasp the Noether theorem as a fundamental theorem of physics that defines plenty of quantities.
i largely agree, but there's a subtle problem with this: what if momentum isn't conserved? how should we define it then?
@@bayleev7494
Well, if you assume that certain symmetries occur in a system you can derive expressions for conserved quantities (according to Noether). No one prevents you from calculating these expressions if the symmetries no longer hold true.
Let's take a look at an example.
Let's say we have a simple mechanical one particle system that obeys the laws of Newton.
The whole system can be described by finding a proper Lagrangian L that depends on the position and velocity of the particle at all times.
Let's assume the system is time translation invariant. It follows the following conserved quantity according to Noether.
E=dL/dv*v-L
where v is the velocity of the particle.
This quantity we call energy.
Now you can let act a time-dependent field on the particle. In that case the symmetrie hold no longer true (and energy is no longer conserved) but you can still calculate the expression dL/dv*v-L and say that this is the energy of the system at any given time as long as you know the Lagrangian L of the system.
Does it make clear?
This video actually makes a good point about how physics is taught. A subject like math is built from the ground up with a rigorous framework, but physicists just write formulas without proper definitions and have an expectation that no one will actually understand anything. Someone famous said "No one really understands quantum mechanics." Can you imagine saying that about any math field? "No one really understands number theory." "No one really understands algebraic geometry." No, that would be ridiculous, since these are fields that are built in a rigorous framework with proper definitions, and the people who study them actually understand them.
As far as I know, standard quantum mechanics (not venturing into quantum field theory) does have a rigorous formulation. The confusing stuff comes more from the physics, like entanglement and probabilistic measurements.
@@eigenchris what does energy operator and moment operator operating on a wave function actually means? If wave function represent the wave, what is the logic behind to use the product with its conjugate as the probability of particle, apart from after some calculation, it seems it matches our measurement? If the product represents the probablity wave, shouldn't we actually apply operator on the product instead of the wave function itself? Any logical justification for throwing Imaginary part away or multiple the conjugate in order to obtain a real number? When reading quantum mechanics, often i felt, it seems follow these math steps and the calculation gives a good result that closely matches experiment. however, each of these calculation steps does not make much sense, or at least, not well explained and too hard for me to understand.
@4:07 “destroy momentum” made me crack up so hard.
10/10 best video i've seen in days.
baia baia
@@memo26169 xD
Yeah but i don't know why
I discovered your Tensor for Beginners series googling what a Tensor is, and I end up studying special relativity, hypnotised by your reasoning. I want to point that you only require from your audience basic matrix multiplication.
I think this is the first time in my life that I have met a living genius.
My heart goes out to all the struggling physicists currently imprisoned for life in the frictionless vacuum ❤️
I'm so glad this video found me. Struggling through my PhD in mechanical engineering right now, ans the amount of times someone has said "well actually, its more like this..." to me is unbelievable.
When asked such a question, I reply "Do you want the short answer, the long answer, or the 3-trimestrial course?"
Can someone explain to me what momentum is?
evil
p= int(F)*dt
I once thought about this while being in high school (currently a Physics major) that momentum is a clever combination of mass and velocity that gives you an idea about the impact when two bodies collide.
Well you were true that momentum is generalised to a very complex level in current theories of Physics but foundationally there is no meaning to momentum if we are studying just a single particle. When two or more particles interact, they do require some kind of a defining quantity that has information about their respective inertia and the motion they have.
Momentum is trying to give you an information about how much mass changes its position in unit time.
Still my explanation lacks the clarity it should.... Lets try a bit more and figure it out.
mass times velocity!
Newton referred to it as the "quantity of motion". A measure of how much motion or movement occurs.
It increases with mass because more matter preformes movement and increases with velocity since the same mass literally moves more 😁
That's how I think of it intuitively.
2:58 Probabilities are just the square root of the 'momentum operator'. That's why there's an "i" there. The momentum operator works strictly on the plane perpendicular to the Real numbers too, hence why it's imaginary 😶.
Captain America giving me a motivational speech but then getting me arrested anyways was *very* heartbreaking. Not to mention the fact that Tony could have just chosen to explain momentum to me instead of eating shawarma after throwing me into a frictionless vacuum chamber (I feel like he specifically designed that too)
This actually made me sadder than I already am
Dude I felt that...I really felt that. Studying physics has been the most humbling thing.
The first half is my worst nightmare, as someone starting a physics major this fall.
This video is an exaggeration. Usually you work up to these concepts slowly, over the course of months or years. And a good prof should never make fun of you for getting an answer wrong. But the feeling of not knowing what momentum is anymore after finishing a physics degree is kinda true, at least for me (particularly in quantum). I hope you enjoy your major and have fun, even if it will be confusing sometimes!
To add: you will most likely feel extremely stupid compared to the rest at some points. But so will most of the rest. So don't stress it ;)
@@eigenchris but aren't they all just theories getting better as time passes?
@@maxwellsequation4887 Yes, but the theories are increasingly more mathematically abstract and get separated away from your normal intuitions about the usual flat 3 dimensional space with objects obeying newtons laws.
Let the many problemsets guide you as you build the intuition that will carry you through this degree.
"Anyway, the Avengers beat you up" 😂😂
Awesome story. I really loved it and had a good laugh. Please keep making such videos ❤
Tons of love.
3:24 I felt that picture.
...I did not ask to be personally attacked on a Good Friday. *curls up into a ball and cries*
Your explanation and your efforts on your courses are outstanding, all respect to you bro, Thank you
single-handedly the best video on TH-cam.. no, on the entire internet. Bravo.
I never knew this could be so realistically motivationg
Supposedly a joke video, yet I found this to be one of the most informative and educational physics videos I've ever seen.
Very condensed way to present a lot of ideas. Excellent work.
You mad man, that is the funniest thing i ever see in the whole damn week. Really nice video. Love your series on relativity btw
1:31 in our country's highschool you actually do this.
But none of these inertia tensor crap, you just memorize the moment of inertia formulas for a bunch of shapes like sphere, cylinder, rod etc.
"Inertia tensor crap"
Dude, its a university class , the stuff is way beyond highschool coverage
@@unnikrishnanvr186 yeah I know.
I didn't mean to imply that our highschools were in a higher level, just that we did a simpler version of it, in university you learn the derivation of those formulas and much much more
@@unnikrishnanvr186we have it in India too. It's not this much higher level tho
“which has the square root of negative 1 in it for some reason”
most accurate words ever spoken
I'm a MSc Physics student. After all these studies i don't what I studied ??🙄😑
And then you started a youtube channel 😂😂
@@aniketyadav7993 a DIY channel
Please do not the cat.
Does it rhyme with Harmonic Oscillator?
Sathyam
4:40 best part
I feel like this a lot. I remember when gravitational waves were first discovered. In excitement I rushed to wikipedia and quickly found the GW page. Eagerly, I read the first paragraph. There were 11 words with links. I didn't know what any of them meant. I just had to laugh so that I wouldn't cry.
Thanks for doing what you do to make the world a little less inscrutable. I'm looking forward to your Tensor playlists. I've gotta build up the maths first though. Cheers!
I feel your pain. I remember when I had an assignment due the next morning and needed to calculate some line integrals, but I had absolutely no idea how to do that or what that even meant. This feeling of being too stupid built up the whole semester prior until it reached this "grand finale" the moment I failed the very first assignment of the semester. I was honestly just devastated that it had come to this. Maybe I shouldn't have, but I quit right then and there and never visited another lecture. Sounds kind of irrational when I explain it like that, but believe me when I say I never felt so stupid in my entire life.
I'm in electrical engineering now and I feel a lot better, but videos like this help me get over this horrible experience still lingering in the back of my mind.
We all experience hardship. We are not too stupid, no one is. And when we feel like we failed, we should get back up, brush the dust off our shoulders and try again, because that's all we can do.
I know nothing about physics and continue to know nothing after watching this video, me thinks that that's for the best.
Dude!! Never stop making these!
I subbed to your channel because of your tensor series and getting this was a surprise I never knew I wanted so badly!
This is accurate. High school only teaches us about magnitudes and gives no context to what velocity and acceleration are. Later you learn about Multivariable Calculus and that velocity is dr/dt, where r is a vector. Acceleration is d^2r/dt^2. That is when it makes sense. The reason why high school never gives context to acceleration and velocity is to hide the hard truth.
I don't think they are intentionally trying to hide the truth. They are just presenting a limited scope of the truth, at a level that is reasonable for a class of high school students to understand. And not having the background of calculus available, really limits the amount you can teach at a high school level, as you are limited to the special case of constant acceleration.
For the same reason that a elementary school teacher tells you that you can't subtract 3 from 2. I think most teachers of any grade level know about negative numbers, and would tell you about them if you asked about them outside of class. It's just not relevant to the scope of the class they are trying to teach, and you are far beyond the intended lesson that you'll just end up confusing yourself and others, if you insist on introducing negative numbers before you master subtraction in the purely positive case.
Not at jee advance level
@@carultch Wait what? In my high school, you learned calculus in physics class because you needed it, and the calculus class was still trying to teach limits, and only gave up and taught calculus later on.
@@psychohist I can't speak for every high school. This is based on my experience. Your experience may be different.
Calculus is usually a senior-level subject in high school, or a college subject, so if you're trying to teach a physics class much earlier than that, you'll have to abridge it to work with the background the students likely have.
You certainly aren't learning detailed techniques of integration, like parts and partial fractions, to cover the basics. At most, you might learn a limited scope of calculus for the topic at hand. Such as the power rule, which I think most students can handle with just an algebra background. Easier to learn the power rule, than to memorize the formulas that came from it.
This is the most depressing April Fool's Day post EVER. But thanks for posting this. Will convince a lot of people that instead of Physics, you should major in Math!
watch his last april fool's video th-cam.com/video/aewo8otGAAQ/w-d-xo.html&ab_channel=eigenchris
Bruh
0:36 the stache 💀
🙋🏻🙋🏻
Yoooo 😂😂😂
The best part about it is that no one explained that they are the same thing!!
P=mv applies in relativity under Lorentz transforms
Iw=L is kinda like adding up all instantaneous momentum’s…so adding up lots of little p=mv’s
And quantum physics…well…that’s another story haha
But in Lagrangian mechanics the Lagrangian is defined in terms of potentials, of which the time derivative can be thought of as like a change in force ie change in momentum
Boom…it all makes sense. All you need is p=mv
Might’ve explained Lagrangian wrong but oh well I’m just as confused as the next guy idk how I made it this far
My entire life of studying physics just flashed before my eyes 🤣.
4:29 is seriously a vibe.
Okay my friend is this was amazing. I'm sure all of your physics courses are really good but I'm telling you you should have a side channel in humor. You had me all the way along just laughing and enjoying the whole thing. This is a work of art
I showed this to my high school physics teacher, she began crying.
Now I understand what's wrong. I'm in a frictionless vacuum.
Never watched anything this relatable in my entire life 😭
I was expecting at some point that momentum was the integral of force. But you quickly jumped beyond my personal understanding.
isn't work the integral of force?
@@reckie1000 no, work is the integral of force TIMES VELOCITY. And Steven's right, since (as long as mass is constant), F = ma = mdv/dt = d(mv)/dt = dp/dt, so p = Integral of F dt.
@@reckie1000 Depends on what the variable of integration is. When the variable of integration is position, that's work. When the variable of integration is time, that is impulse, and impulse becomes a change in momentum.
Time and distance are the same at the end of the day, so whats the difference really?
@@deltalima6703 One difference is the units. Time and distance might have the same units in Planck units, but not in the units familiar to us.
Another difference is that the variable of integration for work, needs to consider all possible directions in space, and so it is really a dot product line integral, rather than a simple integral relative to the variable of integration.
For integrating relative to time, the direction is implied to be in the axis of the dimension of time, no matter what, and forces are never directed in that direction. You can think of impulse as a hidden cross product, because it is a multiplication of two vectors that are guaranteed to be perpendicular. Though you don't need to think about cross products, because time is ordinarily treated as a scalar.
Perhaps there is a unification of work and impulse in general relativity that makes use of the generalized 4-velocity and tensor calculus, but I haven't explored it.
Reject physics, return to mathematics.
Physics is interesting lol we can't leave it
Goated opinion.
@@theothetorch8016 🤣🤣🤣
Don't do that, currently I am suffering from ma 105.😢
Physics is so cool❤
God bless
Becoming the DVD logo seems like an adequate pumishment for the crime of trying to destroy the universe
"momentum=something moving"
"No that doesn't sound scientific enough"
"Uuuggghhh M=mass×velocity"
"Yea that sounds good"
Bro really became a supervillain because he couldn't understand calculus of variations...
Based on many true stories!!! Lol, that was so funny, and still being in high school I learned about momentum only this year (12), and I cannot believe after 12 years in school I'm nowhere career-wise and knowledge-wise on any topic... The worst is the time pressure for sure...
Well you've now got the foundations, and should be able to add any skyscrapers of focused knowledge you could need for the future career(s) you'll decide to embark on.
Lol, pull the other one...
I got my bachelor’s degree in Physics with flying colors. I still rely on the solution manual whenever my juniors ask help for their problem sets. Plus, I’m in a constant love-hate relationship with Physics. 🤣
Why is this label a "joke video?" As far as I can see, it's my exact life.
Ah yes nothing like high school physics where we experiment on frictionless planes with no air resistance.
I thought I had a hunch what momentum was some time back in the late 90’s. I told a momentum obsessed friend about my hunch. He said I was wrong. The hunch never left me. Now I know I was indeed wrong. Thank you. 🤓
Edit: he was an engineer, by the way, so he was probably wrong too. That gives me some kind of comfort. Now I can finally start living my life.
I'm curious now
What was your hunch?
2:06
What y'all be doing then?
Brilliant! Confusion is the gift that never stops giving.
My journey with biology too, famously the science of exceptions...
Science is the science of exceptions.
I looked away at my homework for a second then the avengers were here
When you realize that in an elm field qA adds up to mv so that the momentum was a disguise for the impulsion, so you look for further explanation and you find this video telling about ur life
It gets even worse when mixing languages... My first language uses impuls for momentum, but still says moment(um) to torque. And then angular momentum is 'impulsmoment'. -_-
Its common terminology everywhere outside the anglosphere. Angular momentum = moment of impulse. etc etc
@@mikhailmikhailov8781 In Spanish it's just a literal translation of the English terms.
Angular momentum - momento angular
Linear momentum - momento lineal
But
Moment of inertia - momento de inercia
Moment of force - momento de fuerza
Spanish language Wikipedia uses the terms "cantidad de movimiento" (quantity of movement) and "ímpetu" (impetus) as synonyms for momentum, even though I've never seen those terms in Physics textbooks.
This video made me laugh several times haha. While somewhat dark, this video reminds me of when I got my B.S.E. in Engineering Physics and now getting my PhD in Biomedical Engineering (though my work focuses on continuum mechanics of soft tissues and I continue to learn advanced E&M, QM, and GR on my own). There's always a more generalized definition lol. Really well done
Momentum is like speeding down the road at 60 mph, hitting a patch of black ice, saying "whoa mule", and nothing happens.
This was actually a really good explanation of momentum and changes to it!
Man, I think I laughed a little bit too hard on this one 😂.
I saw this somewhere else and I had to immediately come and subscribe. This is just so accurate, I’m in tears .
5:06 It's not the third choice. Unless you also happen to be a quantum particle.
Very nice video.
This applies to chemistry in general too. It goes from being just a memorized operation with cool breaking bad font letters that have dots around theme and unique properties, to then truly getting that theyre bonding atoms that make up everything, to then learning how the bonds and molecules work, and then getting that whole paradigm shattered by learning about electron orbit clouds making the previous images you had in mind a joke, and than you realize every bond and molecule is just loosely grouped and defined ways of protons neutrons and electrons interacting. AND THEN you learn about quarks and quantum physics and you realize the thing youve been learning about basically does not exist and is just a way for us to describe physics on a more macro scale (ironically the most micro things people think of, atoms and molecules)
And then you might stumble across string theory and realize even those quantum fluctuations are not base reality.
The rabbit hole truly never ends, i guess momentum is the rabbit in this case
This video, right here, is a perfect encapsulation of why I'm not a scientist.
This reminded me of my first lecture in University chemistry. "Everything they taught you in school is wrong. Welcome to Schrodinger's equation."
In India we learn this stuff in high school to crack exams like Jee, Neet, Cet, etc. I can feel your pain bro
This education system is killing my curiosity. I am not the same kid as I used to be when I was a child. I was always curious to know how things worked and I used to learn them with interest. But bow as I am in grade 11th I have a pressure of clearing Jee advanced and get into an IIT or other good college to become a robot 🤖 and work in an boring company.
Dude I feel you. I don't know if it would help but there is a TH-cam channel called flipping physics which has a jee playlist. He helps more visually to get the idea but if you ask me, momentum is some kind of impact or smth
you kids are studying momentum vectors and tensors for jee adv?
wasn't it difficult questions based on high school concepts only?
Eigenchris this was amazing! I hope to survive in my general physics class next week which is unlikely because I´m in a way to early phase of my studys. But with your channel I still have a chance!! Greetings from Germany.
wait this is a great result wtf! 0:54
This isn't even a joke video; this is an autobiography
What's great is that joke is the momentum continues to give you dub after dub
What about the variation of the action with respect to varying the spatial coordinates of the endpoint? Huh? Huh?
Come to think of it, though, isn't the real momentum the friends we made along the way?
3:54 Me in college, knowing that momentum isn't ρ=mv but I can't write that otherwise I'll fail the class 😝. Not like it matters either, we're not studying contexts where it's relevant to use another more precise formula 🤷♂️.
This was not a joke really. You brought out the confusion in Physics wonderfully. If you think about it, most of the ideas presented to us in high-school and college (and beyond) is sort of doled out by an authority. So p = m*v is just a formula to be memorized and you don't get to question why is the product of mass and velocity a special quantity? You have to just follow (or else you are a bad student of science, and will be dropped from further science education). Even Einstein did not have a clear understanding (nor does anybody else) as to why "inertial mass" (which features in Newtons law F = m*a) is identical to gravitational mass (which features in weight = m * g), so he simply put it as an axiom in his general theory of relativity. Ask even those scientists working at CERN - "what is mass?" and even they will look confused. Our science education is really very shaky and indulges in a belief system. We hope this changes, hopefully soon.
This video is going to blow up one day and I am all up for it
“Bouncing in perfectly elastic collisions” 😅
As a graduate student, this hurts....to the bones
Freaking love it!