All physics explained in 15 minutes (worth remembering)

[@ArvinAsh]

For those that want more in depth information on some of the subjects I talked about in this video, here are some detailed videos I made: 1) Newton's Law of universal gravitation: kzbin.info/www/bejne/g3LTn5ltgZmaapY - 2) Entropy: kzbin.info/www/bejne/imemqYdqdqqGebM 3) Electromagnetism and the speed of light: kzbin.info/www/bejne/fISoe2ePgb2nqpo 4) Special Relativity: kzbin.info/www/bejne/kHLJaHmOns1ggMU 5) Einstein's General Relativity: kzbin.info/www/bejne/qqu0dGarjrFpbbc 6) Quantum mechanics basics: kzbin.info/www/bejne/nIGVhXStbLOhjLc 7) Extra Credit: 4 fundamental forces of nature: kzbin.info/www/bejne/bGecgoiAp6tnq5I

[@lucface]

Arvin Ash Thank you Arvin, you rock!

[@impracticalwill2771]

So a weighing machine shows us our mass??

[@ArvinAsh]

@@impracticalwill2771 No it shows us the weight which is force times mass. If you take that machine to the moon, it would show a different number.

[@impracticalwill2771]

@@ArvinAsh ooo thanks 😀

[@EXOPLANETnews]

kzbin.info/door/RF3J0ALbtztpYya4lEdr7w

[@coolmaster2-589]

Well if your going to teach physics you gotta start from the beginning, it’s a warm summer evening in Ancient Greece

[@leerush5945]

I know where this is from🤣

[@roopalidhawan6170]

Big bang theory

[@steviepigford2356]

WOW...WISH TO BE THERE

[@maimoonajaved3804]

Hahaha sheldon cooper ❤️

[@naina4288]

LMAO

[@nekoeko500]

I like how he explains the speed of light at the speed of light.

[@cosmicrider5898]

c is the symbol for lightspeed. .5c= 149,896.2km/s For americans. 149896.2km/s= 93,141.18mi/s 1c= 299,792.5km/s For the US . 299,792.5km/s= 299,792,500mi/s I feel like I should add reference examples but its like crazy fast..

[@cosmicrider5898]

.5c = 440,495 .45 mach if that helps

[@bobnewman6196]

And didn’t age a bit while doing it

[@arslanrasit]

lol exactly

[@inuka6969]

why this is so funny?

[@abdulrahmanhani2179]

When your final Physics exam is in 15 mins and you barely studied anything:

[@irahngio]

I joined a quiz bee contest and this is what Im watching 2 hours before the contest as a review lmao

[@deletioninducedin7days919]

@@irahngio I'm guessing that your quiz is done, how did it go?

[@voxx3]

هههههه

[@andrii5054]

Thats nothing to be proud of

[@maturecheese9688]

@@andrii5054 sorry mom...

[@jellybelly9662]

It’s insane that the same subject I hated and was forced to learn in school is the same subject I am up at midnight binge-watching for fun 🤩

[@jennifernorman9655]

Same here! 😊

[@unknowngba]

Same here. Infact I am thinking whether I can restart my learning from the scratch after many years of being a commerce student and professional!

[@annacichocka7734]

Some things you have to grow up to and experience life to get to. And Sometimes You have to smoke bunch of cannabis to Want to learn about physics😂👍

[@superduperman6535]

@@unknowngba aiiiyoooo meee too

[@programmingpersistence5716]

are you will to open a textbook book and solve basic kinematics problems?

[@ammarbayyari]

As a physics PhD student, I gotta say, your videos are some of the best I’ve seen at explaining physical phenomena. Thank you for making these to have more people interested in physics, everyone should appreciate the beauty of this subject.

[@ArvinAsh]

Thanks, I appreciate that. All the best in your pursuit. The world needs more physicists!

[@Black-vt5vb]

@@ArvinAsh I am 14 and I wanna to do something with physic but I don't really now what jobs are with physic

[@adrianlowery7175]

I bet this guy isn’t actually a PhD student

[@phatan1845]

Big Ole k

[@matko8038]

@@Black-vt5vb ask your physics teacher.

[@Strivarn]

Physics is not about remembering , Physics is about Concept - Walter Lewin

[@gaudencioalejandre118]

Well sometimes our Physics teachers are not good or are just boring when teaching concepts in physics.

[@venomxhawk8427]

Walter Lewin is DA BOSS

[@ishmalala]

@@gaudencioalejandre118 then find other ways to learn such concepts. i was curious how helicopters worked and the videos i watched didnt throughly explain gyroscopic precession so i spent hours learning what just one concept was so i could understand the rest lmao

[@kanseidorifto2430]

Fire determination

[@rebeccatenney7641]

I think you should stop quoting Walter Lewin. He is a stain on the physics community now.

[@jehanr]

5 yrs of engineering and I still don't really get entropy

[@gabrielcaluya6708]

i heard that taking off the word "disorder" would make things easier to understand, and it did.

[@leomadero562]

Energy can only do things when theres different concentrations in different areas, for example a cold spot and a warm spot. You can use this to do whatever you want, make kinetic movement with an engine or catalyze a chemical reaction. But entropy and inneficiency means that the energy will become useless once it mixes. The cold and hot spots will become just warm, and there will be no way to use that energy to make pressure differences or anything else because in order for _anything_ to happen, there must be a flow of energy, from high to low or low to high. But when it is all average, there stops being high or low.

[@leomadero562]

Another way to describe it is to stir a cup of water. There is energy in that glass, shown by the water's movement. But with entropy, the water stops swirling. The real life problem is that this is the state the universe is in. For the cup, you can just stir it to give it more energy, but you can't just give more energy to the universe.

[@elgooges]

Nobody does.

[@Usernotknown21]

Entropy is information gained

[@terencerucker3244]

I'm late to this party but I wanted to let you know that your explanation of relativity and the graphic of the two trains has helped more of my physics students than any thing else I have come across. Simple. Elegant and accessible. Thanks for the great videos.

[@ArvinAsh]

Glad it helped.

[@sidharthshankar5198]

Bro 456 likes and just 1 reply (now2) that too from the channel itself 😂

[@SalmonBoa420]

Still a very underrated channel.

[@Madara-zt8pn]

☹️☹️

[@georgequalls5043]

I feel I have a reasonable chance of understanding Arvin. Even the really hard stuff.

[@EXOPLANETnews]

Hey guys if you like space videos then do visit my channel once pls 🙏 🙏🙏 🙏😊

[@tomashull9805]

@@EXOPLANETnews I have space but I don't have time...

[@tomashull9805]

It has space for improvement but t needs time... If Arvin removes his materialistic bias...

[@Thefuzzion115]

Newton: “Okay let’s just use this small apple as an example of one Newton for this demonstration on my theory” Physicists hundreds of years later: 1 Newton = one small apple

[@cattyom3]

Is tgat true, 1 apple = 1 Newton? It confuses people outside physics fan you know😅

[@mcbutt6149]

Fatima Al-Amri it’s close since an apple weights around 70-100 grams F = ma, = 0.1 x 9.8 = 0.98N round up = 1N so yeah its 1N obviously not all apples are 1N but they average out to be 1N

[@gertjan3329]

@@cattyom3 no sadly not, that would be incredibly funny! A Newton is 'simply' 1 k*g*m*s^-2 (F=ma, so the units for mass and accelerations multiplied), so one newton is simply the force on an object accelerating at one m/s^2 (one meter per second per second) that weighs one kg. This makes it so that you don't need a constant in his second law which is ofcourse very handy.

[@dionzapata7959]

@@mcbutt6149 you know I just started getting into these physics vids and this comment proved the physic major stereotype of rounding 🤣🤣 "0.98,round up, equals 1"...."pi essentially equals 3"

[@EGMAG]

I fig Newton equals 3 small figs !

[@caninelynx0747]

I’m an art student who slept through almost all of those classes, failed miserably on both math and physics in high school, yet somehow youtube is making me fascinated by them rn.

[@waikard267]

Because it's a different environment in school. Learning because you are forced to learn is way different from learning when you want to.

[@dragonvarine7553]

@@waikard267 Yes, but I also disagree at the same time. Clearly people are interested in science regardless. People like learning about the comprehensible side, like how energy cannot be destroyed nor created, or how photosynthesis works in plants. They dont want to know the equations, the prerequisites, or doing the exam. It can be boring. Science is interesting to many, but not many wants to put the effort into it.

[@SumitYadav-ik2df]

@@waikard267 lol no. People with natural curiosity about nature will always go for stem courses. Arts isn't essential for your making sure your species survives. It's just there to diversify what already exists in terms of "culture". Sooo not so bright people like that because it's dumb and easy to understand. It's simple as that . Take any science student and throw them in an arts class and they'll still score more than your arts students. Throw an arts student in an science class . They'll fail miserable. Regardless of your environment

[@azmard4865]

@@SumitYadav-ik2df if only all Indians can walk the talk and make South Asia a better region. Your argument whatsoever holds no substance. Just that typical brag one would expect from an Indian. I was dumbstruck by your shallow cleverness. Did you score 100% for JEE and whatnot or something 😮

[@azmard4865]

@@marinaaguas9219 haha why bother arguing with that typical Indian? Not just supporting the disgusting Israhell, but also proud with their castee stuff. God.

[@satyaprakashbhuyan9266]

This is exceptionally explained. I was also a student of physics and can somewhat understand the complexities involved. I only wish that he should have taken half an hour instead of 15 minutes. Hats off to you Sir and thanks.

[@fishtoastie]

Duuuuude. For years and years I never understood why time slows down when you move faster. Your diagram with the two flashlight beams completely cleared it up! Subscribed.

[@abdusselamzahma7474]

You can't sense the difference by moving normally, it's like a fraction of a second

[@ericstout7336]

Same, i finally understand it now

[@Anonimowany1]

And you most likely have misinterpreted it, because it was explained very badly and easy for someone to misunderstand the concept.

[@Anonimowany1]

@@ericstout7336 You dont.

[@jokerman9295]

Time doesn't slow down for you when you're moving fast, your "proper time" is always the same. Your time just appear to be moving slower from the perspective of a second observer outside your inertial reference frame. Edit: Then if you change directions and accelerate back towards the second observer, their clock will be moving a lot faster from your perspective. When you finally complete your journey and return to the same frame as the second observer, they will have aged a lot more than you.

[@Noci0]

Here we go boys. I'm about to become a physicist.

[@kimdaelhing9169]

Pfft 😂😂😂

[@lilfr4nkie]

Right here withcha

[@WhatWhy42]

Me too. Lmao

[@aniketyadav7993]

😑😑😑😑😑😑😑😑😑😑😑😑😑😑😑😑😑😑 (-_-)(-_-)(-_-) (-_-) 👕 👖

[@unknown-mn9wo]

Good luck

[@kazuhaatyourservice7552]

Me: I feel like I know everything Exam: “*gets 0 score*”

[@halicusnguyen8864]

*surprised pikachu face*

[@xcross8537]

Because you get nervous in exam room🤔

[@botyashgamer6082]

Getting marks is not important what did you learnt is important

[@GentlemanlyOtter]

@@botyashgamer6082 i couldn’t have said it better myself.

[@joshuaquezada9363]

@@botyashgamer6082 You're right, I myself prefer understanding things first rather than just applying all kinds of equations and formulas that I don't fully understand why they are like that or where do they come from.

[@ibhondo]

Thanks!

[@abhishekray5498]

He is expressing all phenomena better than my professor.

[@rahusphere]

J D lol. here comes the gatekeeper.

[@monsieurmitosis]

What a condescending prick you are. As a comment on the generally failed classroom format, it’s valid enough.

[@EXOPLANETnews]

Hey guys if you like space videos then do visit my channel once pls 🙏 🙏🙏 🙏🥺

[@elwoodzmake]

@J D so, you figured out electrical charge without experiments or being taught?

[@tomashull9805]

In Quantum Mechanics it is called interpreting...

[@emiliomencia7429]

Excellent. This is the most important thing we have: science and knowledge, not money

[@andromedaiscoming185]

Money is apart of economics isn't it? That's important in a different realm of society.

[@emiliomencia7429]

@@andromedaiscoming185 money is not bad, is necessary in the world that we live. The problem is when money is the goal of life, is a big mistake because generally is opposite to knowledge

[@andromedaiscoming185]

@@emiliomencia7429 ok yes money doesn't equal emotional well being, I agree. Lack of money though can be very painful because society is built on it. if you can't contribute to society you don't make money, if you don't make money you don't eat or have a place to live then you have to rely on charity or government help or you just become homeless on the street. That's society. Before money it was land and cattle and gold and silver. Gotta have something that's worth something. If not you have to go into the woods and grow vegetables and fruit trees and build a house from logs and build a chimney to keep warm and kill animals for fur and protein. That's ok but you'll be outside of society.

[@MT-in3tp]

Science and Money compliment one another. Without money science won't be developed further, and without science generating money isn't truly imaginable in this day and age.

[@xianzai_ad1928]

@@andromedaiscoming185 freud would say would wise

[@kalanaherath3076]

Arvin, You do NOT know how thankful I am for this video. I've always been interested in physics since my childhood, but gave it up later as a rather foolish act of rebellion against the forceful insistence of my parents that I become a doctor. (They themselves are both doctors and I am from an Indian family, so you can imagine what pressure I was in) Anyhow, since the education system in our country is structured such that all science graduates must go on to become doctors, I gave up the sciences, and having done so, I pursued Law at University. These details about my life, youth and interests will no doubt bore you, but the reason I state these is that as a practicing lawyer who never had this interesting of a science teacher as you clearly demonstrate yourself to be at any period of my school life, I feel forever indebted and grateful to you from the bottom of my heart for so artfully piquing my long lost interest in science once again, to the point where I have now decided to expand my knowledge in the sciences in the duration of these rather unexpected days of pandemic where I am mostly at home with little to no clients in my practice. Thanks a lot once again!

[@ArvinAsh]

I'm delighted to hear that! It's never too late to learn about things you have a passion for.

[@kalanaherath3076]

@@ArvinAsh Thank you, and please keep continuing the great work

[@eddielacrosse2]

First day of 2022 and I’m sitting here with a Blunt digging deep into this. Quantum Mechanics has peak my interest heavy. Thanks for the content ! Science is life.

[@spiritroseee]

Me too!!

[@anonymousyoutube4588]

If any Indian students are seeing this , then remembered and learn this whole video line by line because whatever in this video says this is a summary of class 11th and 12 th physics in India...by understanding this video properly can lead u to feel easy to understand class 11 and 12 th physics.

[@amarjeetyadav8302]

After board exam 20-21 cancelation I'm watching this 😅😅

[@shivanshchaurasia2959]

@@amarjeetyadav8302 me too 😎

[@I_Am_The_Pataphysicist]

you guys learn thermodynamics and relativity in 11/12th class?

[@shivanshchaurasia2959]

@@I_Am_The_Pataphysicist yeah in 11 but why ?

[@GammaFZ]

lol most of this is 10th or 9th grade stuff

[@jpskillet2902]

Key takeaway from this video: I weigh about 712 apples.

[@rutwikmhatre7596]

Ah yes america

[@moonight3016]

Key takeaway comment for your stalker and FBI agent

[@alwinvillero4404]

[ star-spangled banner plays in a distance ]

[@Sumirevins]

I Weight 637 apples lol

[@thedictator1454]

this video is absolutely not for science students cause they know it , if they didnt then they are not science students

[@Proximity94]

Always gets me hyped when he says "...that's coming up right now!". Well played Mr. Arvin, well played.

[@Proximity94]

Mark Steven no u

[@redstonerg.8616]

4 years of engineering and i have to say he got most of the useful stuff for anyone in here. It's always nostalgic seeing how easy some of those equations look at first glance XD

[@elypix2720]

8 years of physics lesson in just 17 minutes

[@SuperAmazingNoob]

This is all just basic stuff

[@ipodtouch470]

Yep it all changes when you actually have to solve problems.

[@amyJ244]

@Science Revolution my brain hurty

[@JarodM]

@Science Revolution Cheeseburgers~👉🍔

[@neerajmehta3461]

@Science Revolution they are not replying u just because there are some limitations to Ur theory As follows :- 1)the electrons or protons repel each other but they get weaker by increase in distance b/w them as they result in being constant. 2)the electrons in mass are capable of repulsion force created other wise it will just of few distance on particles level. 3)charges cannot be free for much time as they need an anti-charge for their neutralisation or to form molecules and intermolecular forces. These are my thinking about your result but it would be excellent to make a bound of charge(which will neutralise and then a mass force created by mass electronic repulsive force b/w them with It will be artificial force created by mankind If there are limitation to my limitations please let me know

[@mukhammadsaidyokubjonov6770]

Author: “Your weight is a force, not a mass” Me:

[@citizenblue]

I never truly understood the difference between weight and mass until I heard your explanation. Thank you.

[@ofeyofey]

If someone asks for your weight tells them it about 800 Newtons oh you mean mass 81 kilograms. 😆

[@JIYASINGH14]

At 3:19 (for those who are actually studying from this video) the distance is taken from the centres not the boundaries of the objects! Probably it was a editing glitch but nice explanation! Loved it❤️❤️

[@ArvinAsh]

Yep, missed it during editing. we fixed this in future videos. Of course, if the celestial objects are very far apart, like the sun to the earth, adding the radius wouldn't make much of a difference.

[@vez3834]

To be extra clear: It's all about the center of mass.

[@atashitabassum7368]

Really a video worth watching. Whenever I feel really negative about physics being attacked always by the odds in "classrooms " and "exams", this video heals me! Though I watch, I can't understand all of them,hope to understand in the near future!

[@robertskogkristiansen7714]

Physics makes me happy! Seeing the connections of the universe is just amazing!

[@jamesmichalski3002]

Arvins videos should be mandatory learning for fundamental physics courses taught in our educational institutions. They are similar to the mechanical universe series video courses and describe various principals of physics with astonishing simplification and clarity. Bravo Arvin.

[@Bill..N]

Outstanding graphics! The Professor we all wish we had.. A pleasure to watch Arvin.. The ONLY regret I Have is that there's nothing controversial to debate in the comments..Thanks.

[@ArvinAsh]

Don't worry I'm about to make several videos where there will be plenty of controversy. lol.

[@markokriegel5787]

I'm a physicist myself, but I really love your discriptions and like your approaches to different phenomena. Great video again 👍

[@ArvinAsh]

Thanks! That means a lot coming from a physicist.

[@ollielast2901]

Thanks! That means a lot coming from a physicist.

[@eggi4443]

Thanks! That means a lot coming from a physicist.

[@gillarheckar]

Thanks! That means a lot coming from a physicist.

[@eyabenfredj2661]

you explained physics in 15mins better than my professors did the whole year !!! total support

[@frederikbjerre427]

You're one of few people who can give me a headache and still make me smile and like your videos.

[@PatClevenger0709]

I have a Master's in Physics and I'm a civil engineer. Always nice to have refreshers.

[@loveoflyricism2769]

Because of the efforts of you men the quality of my life is profoundly enhanced. When I graduated high school I didn’t understand algebra. I was so incredibly weak in mathematics for most of my life. KZbin did something for me that college lectures never could. I don’t know what it is but I just learn from KZbin. Thank you.

[@rhouser1280]

I really wish I took physics in high school! I wasn’t interested, fast forward 30yrs, I can’t get enough! Thanks for your videos man!

[@AndrewPa]

As professional in subject and being skeptical about 15 mins of physics want to say big thank to author - good job.

[@sarthak8802]

Why this channel is so underrated. He is explaining so nicely

[@ryantennyson7562]

Thanks for the refresher. It's like being in a high school physics class again. Your channel has become reference material.

[@ArvinAsh]

Well, if you had relativity and quantum mechanics in high school, I'm impressed. I did not have these in high school.

[@ryantennyson7562]

@@ArvinAsh My high school had a second year in physics with a lesson on quantum mechanics. It's as weird now as it was then.

[@ArvinAsh]

@@ryantennyson7562 That's great, but it's very unusual. Most student don't take QM until at least their sophomore year in college.

[@chaost11]

@@ArvinAsh we were taught the basics of it, duality principle, history and origin, etc. but we were never taught actual QM. I think that may be what Ryan means here. No way a highscool student is taught the maths and theory behind e.g. quantum tunneling and such.

[@romishcraft]

I wish I had a teacher like Arvin. Thanks again, I wish to meet you in person someday.

[@ramalingamvp9067]

I can't stay unappreciative. Though fast and short, very nicely explained. Excellent. Thank you ❤

[@JSPUFC]

First time learning about physics a month ago. I got A’s in all quiz and tests so far. This video made me understand WAY MORE than I did earlier. Thank you

[@anneweber7029]

Shut up

[@Mimixorock]

How’s it been going

[@jasonjones2064]

Answer Gravy: This isn’t part of the question, but if you’ve taken intro physics, you’ve probably seen the equations for kinetic energy, momentum, and acceleration in a uniform gravitational field (like the one you’re experiencing right now). But unless you’re actually a physicist, you’ve probably never been freaked out by seeing a Lagrangian work. This gravy is full of calculus and intro physics. The “action”, S\left(\vec{x}(t) ight), is a function of the path a system takes, \vec{x}(t)=(x_1(t),x_2(t),x_3(t))=(x(t),y(t),z(t)). More specifically, it’s the integral of the Lagrangian between any two given times: S\left(\vec{x}(t) ight)=\int_{t_1}^{t_2}\mathcal{L}\left(\vec{x}(t),\dot{\vec{x}}(t) ight)dt where t1 and t2 are the start and stop times, \vec{x} is a path, \dot{\vec{x}} is the time derivative (velocity) of that path, and \mathcal{L} is some given function of \vec{x} and \dot{\vec{x}}. If you want to chose a path that extremizes (either minimizes or maximizes) S, then you can do it by solving the Euler-Lagrange equations: \frac{\partial\mathcal{L}}{\partial x_i}=\frac{d}{dt}\frac{\partial\mathcal{L}}{\partial \dot{x}_i} This is called the Euler-Lagrange equations (plural) because this is actually several equations. Each different variable (x1=x, x2=y, x3=z) tells you something different. In regular ol’ calculus, if you want to find the value of x that extremizes a function f(x), you solve \frac{df}{dx}=0 for the value x. Using the Euler-Lagrange equations is philosophically similar: to find the path that extremizes S, you solve \frac{\partial\mathcal{L}}{\partial x_i}=\frac{d}{dt}\frac{\partial\mathcal{L}}{\partial \dot{x}_i} for the path \vec{x}(t). The Lagrangian from earlier, for a free-falling object near the surface of the Earth, is: \mathcal{L}=\frac{1}{2}m\left|\dot{\vec{x}}(t) ight|^2-mgz(t)=\frac{1}{2}m\left[\left(\dot{x}(t) ight)^2+\left(\dot{y}(t) ight)^2+\left(\dot{z}(t) ight)^2 ight]-mgz(t) For z: \begin{array}{l}\frac{\partial\mathcal{L}}{\partial z}=-mg\\[2mm]\frac{\partial\mathcal{L}}{\partial \dot{z}}=m\dot{\vec{z}}(t)\\[2mm]\frac{d}{dt}\frac{\partial\mathcal{L}}{\partial \dot{z}}=m\ddot{\vec{z}}(t)\end{array} So the E-L equation says: m\ddot{\vec{z}}(t)=-mg or \ddot{\vec{z}}(t)=-g In other words, “everything accelerates downward at the same rate”. Doing the same thing for x or y, you get \ddot{\vec{x}}(t)=\ddot{\vec{y}}(t)=0, which says “things don’t accelerate sideways”. Both good things to know. You wanna be even slicker, note that this Lagrangian is independent of time. That means that \frac{\partial\mathcal{L}}{\partial t}=0. Therefore, applying the chain rule: \begin{array}{rl}\frac{d\mathcal{L}}{dt}=&\frac{\partial\mathcal{L}}{\partial t}+\sum_i\left(\dot{x}_i\frac{\partial\mathcal{L}}{\partial x_i}+\ddot{x}_i\frac{\partial\mathcal{L}}{\partial \dot{x}_i} ight)\\[2mm]=&\sum_i\left(\dot{x}_i\frac{\partial\mathcal{L}}{\partial x_i}+\ddot{x}_i\frac{\partial\mathcal{L}}{\partial \dot{x}_i} ight)\end{array} But we have the E-L equations! Plugging those in: \begin{array}{rl}=&\sum_i\left(\dot{x}_i\frac{d}{dt}\frac{\partial\mathcal{L}}{\partial \dot{x}_i}+\ddot{x}_i\frac{\partial\mathcal{L}}{\partial \dot{x}_i} ight)\\[2mm]=&\sum_i\frac{d}{dt}\left(\dot{x}_i\frac{\partial\mathcal{L}}{\partial \dot{x}_i} ight)\end{array} And therefore: \frac{d}{dt}\left(\sum_i\dot{x}_i\frac{\partial\mathcal{L}}{\partial \dot{x}_i}-\mathcal{L} ight)=0 This thing in the parentheses is constant (since it never changes in time). In the case of \mathcal{L}=\frac{1}{2}m\left[\left(\dot{x} ight)^2+\left(\dot{y} ight)^2+\left(\dot{z} ight)^2 ight]-mgz we find that this constant thing is: \begin{array}{rl}&\sum_i\dot{x}_i\frac{\partial\mathcal{L}}{\partial \dot{x}_i}-\mathcal{L}\\[2mm]=&\left[\dot{x}\frac{\partial\mathcal{L}}{\partial \dot{x}}+\dot{y}\frac{\partial\mathcal{L}}{\partial \dot{y}}+\dot{z}\frac{\partial\mathcal{L}}{\partial \dot{z}} ight]-\mathcal{L}\\[2mm]=&\left[\dot{x}(m\dot{x})+\dot{y}(m\dot{y})+\dot{z}(m\dot{z}) ight]-\left[\frac{1}{2}m\left[\left(\dot{x} ight)^2+\left(\dot{y} ight)^2+\left(\dot{z} ight)^2 ight]-mgz ight]\\[2mm]=&\frac{1}{2}m\left[\left(\dot{x} ight)^2+\left(\dot{y} ight)^2+\left(\dot{z} ight)^2 ight]+mgz\end{array} Astute students of physics 1 will recognize the sum of kinetic energy plus gravitational potential. In other words: this is a derivation of the conservation of energy for free-falling objects. A more general treatment can be done using Noether’s Theorem, which says that every symmetry produces a conserved quantity. For example, a time symmetry (\mathcal{L} doesn’t change in time) leads to conservation of energy and a space symmetry (\mathcal{L} doesn’t change in some direction) leads to conservation of momentum in that direction.

[@AntonFetzer]

Need to paste that into a TeX editor to read it even though I write TeX code all the time.

[@jasonjones2064]

Anton Fetzer lol...... I really should have checked that first😂

[@TheTatzeLP]

I recommend using the physics package in LaTeX, it makes writing derivatives sooo much easier

[@RahulSingh-dc8js]

I don't know anyone else who can cover whole physics so efficiently within 20 mins. Thanks for making this video sir!

[@paulroe9957]

The chillest, most informative, coolest KZbin channel! Really good when one once had more detailed knowledge but it faded. This brings back a framework of context. Reflecting on it, I then begin to piece the details into place. Love it!

[@quahntasy]

*He is explaining stuff that professors and teachers have failed to explain over the years, again and again*

[@sanathkumar6526]

Lemme explain why....It's all in the brain, when u are in ur class listening to ur teacher, U may be bored or distracted by ur friends AND on top of that, like be honest, When u are in ur class, the thing that's in ur mind is "I have to study well so that I can get good marks" NOT "I need to gain knowledge for the long run".....But here, U clicked on the video just purely because of gaining knowledge, Like there is no pressure of test being done so ur stress gets reduced, Lesser the stress,Better the brain functions....Hence u understand stuff better in YT videos compared to say ur class

[@minh9545]

@@sanathkumar6526 or they are not explain it simple enough.

[@angelee9350]

When teachers discuss, it's boring XD. They act just like robots pretending they understand the material in a deep way. It's lucky if you find someone who's passionately talking about the subject and teaching it with fascination.

[@Bweich]

Because this isn’t the math behind it these are concepts, the math is what is really hard to learn and the stuff of which makes these concepts

[@stuglenn1112]

Ha! Watching this video increased the entropy in my brain....I think. lol

[@YawnGod]

No, it lowered the entropy in your brain and increased the entropy in the rest of the universe as a consequence.

[@ender1242]

How dare you steal our entropy

[@stuglenn1112]

@@YawnGod Are you sure? I thought that increased entropy= more information required to describe the system. Increasing the amount of information in your brain would require more information to describe all the information in your brain. Isn't that how the Paradox of Maxwell's demon was solved, the entropy increased in the demon's brain? Then again i could be all wrong. lol

[@mazocco]

Picture this: high entropy (or high disorder) states are like a mess you cant extract much from it. If you acquire information by any means, like rearranging your neuron connections, you are decreasing its entropy (or it disorder).

[@seal516]

You’re right, you can’t decrease entropy.

[@brendanfan3245]

The best speech so far of the general concept of physics, thank you!

[@JonathonConnorOfficial]

Sir, you are no bald ape. Do not sell yourself short. :-) you are a gentleman and a scholar. Such eloquent video delivery. Bravo thank you

[@kamalpersaud2184]

Wow! This channel is so insightful and entertaining. I am a business student but I am intrigued with the genius in the presenter. I am particularly impressed with the simple explanation of the complexities in physics.

[@myfavsandlikes7478]

I didn’t think this video would be very interesting for me since i spend a lot of time learning physics already, but your entropy explanation was really great. Def got my thumbs up on the video because of that. -edit This whole video was explained amazingly. You went through all the basic concepts so well, i haven’t seen another video before explained so perfectly. Great job man.

[@ArvinAsh]

Glad you enjoyed it!

[@myfavsandlikes7478]

Arvin Ash yeah man i really did. Shared it with a few people too.

[@dimentbarg9793]

Years of physics and never understood why time slows down but this video made me finally understand it

[@random.med.student]

This was so incredibly informative and easy to follow. In this day and age, I wonder how I managed to stay fully concentrated at a 17 minute video. Absolutely beautiful

[@richardmasters8424]

Arvin - many thanks for this. I’m going to show it to all my engineering students after I’ve shown them where the fundamental units come from.

[@stephenward1143]

I wish my teachers made physics as clear and as interesting as you just did.

[@marybrown6659]

Most physics and math teachers are very poor at teaching. VERY POOR!

[@alberteinstein7683]

I'm very much impressed by the way of your simple explanation of complex topics !

[@tampanailbarllc2816]

The best introductory physics video I have seen. Thank you.

[@scottrobinson4611]

Excellent video. I have bachelors + masters degrees in physics, and I'd say this is just about the clearest and most concise summary possible. I come from a family of people with very few formal qualifications, and no university education. Sending this to my mum because I've never managed to get physics concepts through to her, but I think this might just do it.

[@ArvinAsh]

Thanks. Means a lot coming from a physicist.

[@balthiertsk8596]

This is a very amazing video! It explains the wonder of physics and the world in a very quick way, I would even dare to call it, a fun way to learn physics

[@ArvinAsh]

Glad you liked it!

[@robertryder1097]

What an artful summation of physical reality as we experience it - bravo!

[@leahklatt3873]

THis was pretty epic. I love where he is coming from with this. His heart is in a great place.

[@webdesignbyjonny]

I'm a bachelor of physics and I'd just like to say this video is great, what an excellent way of explaining these phenomena! I wish there were more videos like this that were shown to me in high school or in primary education. I feel that people don't realise how truly fascinating the universe is until learning these concepts. Great job 👍🏻

[@somor6043]

Really sir your vdo makes me more confidence on physics. I'm also a physics teacher.

[@al_dawg__6492]

If only all teachers could explain like this I would deffo not be bored

[@stormssf8538]

Studying for 13 years just to forget it and see a man in KZbin explaining it in 15 mins.

[@Garmashua]

Force - is a measure of interaction mass - is a measure of inertia - resistance to change in motion Energy - a measure of various forms of motion and interaction of matter, a measure of the transition of matter from one form to another Energy and Force Words have very specific meanings in science which are not always the meanings that are used in everyday life. The words energy and force are not interchangeable - they are not the same as each other. A force is a push or a pull which is easily demonstrated and felt but energy is a slightly more abstract concept. They are measured in different units: force in Newton's and energy in Joules. When a force is applied to an object, such as a supermarket trolley, the trolley accelerates and moves forwards. Another way of describing the same situation is to say that a transfer of energy has occurred. The trolley gains kinetic (moving) energy and , as energy cannot be created or destroyed, this must involve a transfer of energy. Chemical energy in the body of the person pushing the trolley was changed into the kinetic energy of that trolley. Supermarket shopping is exhausting work! It is the force that causes the trolley to start moving and, as it does so, it gains kinetic energy

[@ArvinAsh]

Very good points!

[@unatocsvemu]

No definition for mass sorry

[@unatocsvemu]

Where did u get big G

[@unatocsvemu]

@Mr. H nobody has definition for mass ...sorry again

[@unatocsvemu]

@Mr. H thats inertia sorry not mass

[@ariunbolorbatmunkh9923]

When it’s 15min before the physics exam

[@lexihendler1524]

underrated comment

[@tarunvarma3323]

This video give more useful knowledge than most courses do in a semester

[@hollyscott5859]

I'm a 8 year old and thus is very interesting keep up the good work!

[@Fangoros]

This is one of the greates videos I have ever watched

[@madenlaur5073]

This needs to be recommended to action filmakers..lol😂

[@austinpaul6220]

It’s summer. I don’t know why I find myself watching this stuff.

[@doyouknoworjustbelieve6694]

Because it’s around you year round

[@larutmrs3313]

Cicolas Nage absolutely agree

[@unknown-mn9wo]

Its much fun when you decide to learn things by ur own not when you feel like you have to

[@lilj3467]

@@cicolas_nage YES! VERY TRUTHFUL.

[@bayleesoto455]

@@unknown-mn9wo same I'm gonna get smarter by the time I get back into school lmao

[@Digital-Dan]

Astounding. I think every individual with any interest in science should watch this video once a year, starting at age 10. Initially, this will serve as a sort of baffling introduction; later, as a review and something tying everything together. Congratulations on this.

[@ustbot7047]

whoa. i really should use KZbin back when i was studying.

[@NRG-um3do]

How much time and effort, editing you took to make this video is really appreciated

[@allika2627]

thanks Arvin. this was so practical to recall physics i've learnt.

[@avante-gardegeckos1233]

I can’t figure out what science I want to study for college, so I’m exploring physics, geology, chemistry, ecology, etc. through this! It’s hard when you have an interest in everything, bc it’s all connected anyways. Thank you for this!

[@johanas3578]

ahh that is such a nice thing to hear, even I relate to the interest in everything part. I hope you've found your interested course. What made you realise that you love science the most?

[@rushwithronnie]

i'm in 11th and now i finally feel that all those years of studying were worth it!

[@XarJobe]

its 1:42am and i have to go to work at 7:00am, but thats a good video bro

[@-Neutron-Star]

Wow, I wish I had access to this video some 25 years back when I was in the 12th grade studying all these concepts!

[@Pelipear]

Wow, I'm from 250 years in the future. Kinda feel bad for these old Gen Z people for not having nearly as much stuff as we have to learn. 1st graders are learning about physics of this level in my time..

[@pigicompany]

Every single movement of life can be explained by physics and that’s the magic of physics and you prove it very well ..

[@iceempress3311]

This guy seriously explained all of this within 15 minutes, while everyone spent years in schools, colleges and universities learning these 😑

[@NunyaBidness-f7t]

If only everyone, in every subject in school had teachers like this, we would be a much better educated humanity. Of all the teachers I had from K through 12 I don't remember a single one, so little was their impact. I certainly never had one like this guy. This video should be played on a loop to newborn babies as they are growing up.

[@ironic57]

I can't understand everything but I still feel satisfied that.i am watching this video is any one else there feeling like this

[@thinginground5179]

When you can't understand a single thing but you feel smart for watching it:

[@zachsss1916]

As an engineering student this went above and beyond as a brief introduction to physics and I learned a good bit

[@Cdictator]

Your explanatory description for the general relativity theory is phenomenal! It solved a long time confusion for me. Thank you!

[@DavideCardella]

Thank you so much for your insight and for how you rendered these deep and hard concepts palatable!

[@gunsmoke5580]

When this man said, “The universe always moving toward entropy is likely why we have a forward concept of time...” blew my mind. It made me understand that a simple change in the law of the universe, and ourselves as perceptive beings would have fundamentally evolved differently. Insanity.

[@drasiella]

I watched a dozen videos dozens of times on time dilation.. from your very simple explanation I think I finally get it a little.

[@jamesdong8179]

When he started listing the 5 main branches of physics I paused after the first one and guessed the rest 4/4. I'm now slightly proud of myself

[@stargazeronesixseven]

The majority are having a limited time to learn new things while working or taking care of the family , so these short concised learning videos are really helpful! Thank You So Much for the Efforts & for Sharing! Stay Safe & World Peace! 🌍🌷🕊

[@williandromatic4590]

10 mins in, i could already say this one of the best summary videos!! Great work condensing them and still being so informative!

[@ArvinAsh]

Glad you enjoyed it!

[@cedricamoo]

as a 15 year old new to physics this vid was kinda confusing but also helpful im now subbed hope to see more explanations from this channel cuz ill need it alot

[@math.physics]

This video truly lives up to its title, condensing an enormous amount of information on physics into a 15-minute video is no easy task, but the creator has done an admirable job. The explanations are concise and to the point, making it easy to grasp even for those with little prior knowledge on the subject. The visual aids used in the video are excellent, they help to explain the concepts in a way that text alone cannot. It's a valuable resource for students, educators and anyone looking for a quick and easy way to understand the basics of physics. I highly recommend It. As an engineer who has always been passionate about math and physics, I was intrigued by modern physics, despite neither relativity nor quantum mechanics were part of any course syllabus at my university. I studied these subjects on the side and found them really inspiring, I would go as far as to say that they gave me a novel perspective on life itself. That prompted me to create some online courses on Udemy on Quantum Mechanics, Quantum Field Theory, special and General Relativity. It’s not my job of course, but I love talking about these topics ans showing the "intution" behind the mathematics.

[@margaretgolias5314]

Say bitchhhhhhhh😂 stop playing

[@sreenathc]

What superb condensation of all the topics in physics explained in such a clear way!! ❤️

[@trigorijkes6692]

I'm 14 and I live in Holland, I am trying to understand it and I can understand it a bit and people call me stupid in school.

[@ArvinAsh]

Don't let others define who you are. Your smartness is not based on other people's opinion. It's based on your own perspective of who you are, and how hard you work.

[@alberteinstein7683]

I too faced the same. Never give up !

[@invademars420]

@@kellymills3636 bruhh I am in 12 class and calculus and physics is my daily thing.(ofc I am from India 😂😂)

[@Anju-sri]

@@invademars420 hope you're prepared for your exam 😊 India

[@penguinpenguinpenguin]

In 8th grade nearly everybody thought air wasnt matter and some thought cars ran on gravity. If youre smarter than them then youre fine

[@superbere]

I swear you are a hero and a savior to students world wide. thank you for helping a new generation of future physicists and others, find joy in the topic youre passionate about