Einstein's General Theory of Relativity | Lecture 2

In this lecture, Professor Leonard Susskind of the Stanford University Physic's Department discusses dark energy, the tendency of it to tear atoms apart, and Gauss's Law.
Einstein's Theory (PHY 27) discusses the different applications of Einstein's Theory of Relativity in particle physics, including Newtonian, Galilean, and Guassian laws; particle attraction and repulsion; gravitational fields; and dark energy.
Physics Department at Stanford University:
www.physics.stanford.edu/
Stanford University:
www.stanford.edu/
Stanford University Channel on KZread:
/ stanford

Пікірлер: 605

  • @joabrosenberg2961
    @joabrosenberg29613 жыл бұрын

    [Dark energy - not related to the course]; Del operator 15:00; Gravitational field and Gauss law 21:00; Gauss theorem 32:00; Equivalence Principle 59:30; Galilean transformation 1:09:00; Accelerating frame of reference 1:12:00; Light motion in accelerating frame 1:18:00; Tidal forces 1:32:00; Curvature 1:37:00

  • @MAR7870J
    @MAR7870J6 жыл бұрын

    he is so patient and calm while giving lecture

  • @mfgman2011
    @mfgman20118 жыл бұрын

    This professor is SUPREMELY patient. The student asking the questions over and over again is justified in asking. He paid for the course. He has every right. But he also needs to be getting his notes out and trying to solve on his own. Otherwise, he's just asking for the prof to do his work for him.

  • @mcdeadsquirrel

    @mcdeadsquirrel

    7 жыл бұрын

    Point well taken....I must agree with you here.

  • @TrailRunnerLife

    @TrailRunnerLife

    7 жыл бұрын

    Totally agree... but I'm thinking of the other tuition paying students; it does get annoying.

  • @blahblahblase1483

    @blahblahblase1483

    6 жыл бұрын

    It just disappoints me that they are paying for this class and aren't even enjoying his great physics puns.

  • @blahblahblase1483

    @blahblahblase1483

    6 жыл бұрын

    visnevskiscom "Information presented in a particular way" is, by definition, a service. But also, it was a joke.

  • @davidharrison7825

    @davidharrison7825

    6 жыл бұрын

    The student was looking at his notes but must have not paid attention when the professor canceled the 4pi, the when he looked at his notes to catch up.he was like, but wait professor ☝

  • @mynyddwrglas
    @mynyddwrglas13 жыл бұрын

    Heartfelt thanks to Professor Susskind and Stanford for making these beautiful ideas available to me. I am following all of the series.

  • @beechersbrookpublishing
    @beechersbrookpublishing13 жыл бұрын

    Thanks Stanford University for posting these lectures

  • @ArieteArmsRAMLITE

    @ArieteArmsRAMLITE

    4 жыл бұрын

    I know.....students pay a lot to be at this seat of learning....so to give this away for free is generous.

  • @bw7925

    @bw7925

    3 жыл бұрын

    All this to disprove the flat earth

  • @morani3x937

    @morani3x937

    3 жыл бұрын

    10 year old comment jesus christ

  • @ArieteArmsRAMLITE

    @ArieteArmsRAMLITE

    2 жыл бұрын

    @@mattwooten830 you are on the good drugs

  • @redpillmath

    @redpillmath

    2 жыл бұрын

    All they know the Einstein's stuff is just a HUGE HOAX that has been devealed at: numbermusicrevolution.com/srt/ Indeed, Einstein's lies allowed many institutions and scholars to rise so much funds rising, so they are not willing to kill that Golden Chicken. Notwithstanding, all this hoax has to come to and end, sooner or later, and many people will have to face justice.

  • @waperboy
    @waperboy14 жыл бұрын

    We're coming into a new era with the internet education. Susskind is one of the greatest teachers available, togehter with a handful others, and I'm very grateful that his lectures are freely available online. I'm 40 yo, regrettably didn't find physics back in the school days, but I've had an exploding interest in physics the last 3-4 years. Now there's the math barrier - luckily, I've taken all the required maths during my education, so some refreshment is needed.

  • @anon6116
    @anon61162 жыл бұрын

    I can’t get enough, this is my idea of finding the bright side of life. Free class at a university I couldn’t afford. I’m loving it🤭😍🥳

  • @rbettsx
    @rbettsx8 жыл бұрын

    The finishing sentence of this lecture gave me a real breakthrough in understanding. In all of these series of lectures, how can anyone thank Prof. Susskind enough for his generosity of spirit?

  • @jameshafford9083

    @jameshafford9083

    7 жыл бұрын

    Robin Betts One of his books (forget which) mentions the great pleasure he gets from teaching physics , for which I'm eternally grateful.

  • @davidharrison7825

    @davidharrison7825

    6 жыл бұрын

    Seriously this guy is great!

  • @andrewmartin3671

    @andrewmartin3671

    6 жыл бұрын

    Do you mean his line that curvatures in spacetime are equivalent to tidal forces? Or a different line?

  • @BrowniesByTheLake

    @BrowniesByTheLake

    5 жыл бұрын

    @@andrewmartin3671 1:47:16

  • @epajarjestys9981

    @epajarjestys9981

    4 жыл бұрын

    @Andrew Martin Not sure what Robin Betts meant, but yeah, that was an enlightening insight right there for me. Or at least it makes me feel like I understand something important which I previously did not. I admire the clarity with which Prof. Susskind can gauge the right moment to feed such illustrative central points of insight to the audience so they can make the connection. Even when he's getting tired. A great teacher!

  • @morani789
    @morani78911 жыл бұрын

    For all of you who say these students ask stupid questions: "We must know. We will know." - David Hilbert Asking questions is never stupid. Not asking questions for fear of sounding stupid. Now, that's really stupid.

  • @chonchjohnch

    @chonchjohnch

    4 жыл бұрын

    morani789 that’s such a moronic position, most questions are extremely stupid and shouldn’t be entertained in a serious environment

  • @alecapin

    @alecapin

    3 жыл бұрын

    morani789, those students are not prepared for this class, and the level of this class is not high, but their level is low.

  • @dsh1667

    @dsh1667

    9 ай бұрын

    I think they approach it from an opposite direction in perceiving the concept'sas myself . I see a concept in my mind and attempt to put the math to it. Others with a more mathematics background I think may see the equation and from that derived the image in the mind. I thought the same at first but I was a 4.0 physics major, not mathematics. I can't expect others to see the concept's presented as quickly. That doesn't lesson their questions however. Koodos to the students. It a challenging concept to truly grasp.

  • @srinic9319

    @srinic9319

    3 ай бұрын

    I think if we look at it as people just discussing things instead of as a “physics lecture”, then we won’t be so annoyed by the questions :)

  • @zemm9003

    @zemm9003

    2 ай бұрын

    Stop defending the indefensible. Some of these questions are atrocious. Really dumb.

  • @googleplususer3009
    @googleplususer30093 жыл бұрын

    Alternative form of the calculation of gravitational acceleration at a point inside a spherical mass. A = m G / r^2 which in terms of whole sphere is: A = n M G / R^2 R : Radius to point on surface of sphere r : Radius to point inside radius of sphere n : Ratio of r to R

  • @bigfuss4135
    @bigfuss41355 жыл бұрын

    The depth of questions that Professor Susskind has to bare and answer is.. nerve-challenging. Hats up for this remarkable professor for his beautiful mind and personality.

  • @ALLenROOK
    @ALLenROOK5 жыл бұрын

    This is some hardcore stuff. I feel so humbled watching this haha. I think I can barely understand it but man its a mindfuck. Its very warming to see that people like the professor not only understand it, but can teach it. And this is only an introduction to relativity!

  • @brianstevens602
    @brianstevens6025 жыл бұрын

    Thank yo u to Leonard Susskind for these lectures. I wish that my physics lecturers 40 years ago at Oxford had covered this!

  • @SasankPonnekanti
    @SasankPonnekanti9 жыл бұрын

    The case where red sphere is inside A question in the class is that a 4*pi is missing from the equation. I think the reason for this would be like this: by dissolving guass theorem we get- 4 * pi *G * integral(rho * cube(dx))=Aperpendicular*- 4* pi * R2. Now as explained by the sir this case has a unit mass density uniformly distributed. so the equation can be written, => 4 * pi *G* rho* integral(cube(dx))=Aperpendicular* -4* pi * R2. As you can see that rho in the integral is taken out of the integral. the remaining integral would be volume of the red sphere. so, => 4 * pi *G* rho* 4/3 * pi * R3=Aperpendicular* -4* pi * R2 => 4* pi * G* rho * R/3 = -Aperpendicular. Now if you check this equation with the one on the right board these would match and no extra pi is missing.

  • @googleplususer3009

    @googleplususer3009

    3 жыл бұрын

    Outside sphere

  • @shawn980

    @shawn980

    2 жыл бұрын

    AHHHHHHHHH! God I’m dumb. I figured that he was right and that the students were wrong because he’s saying that the conditions are different. I didn’t understand how he got his answer until you explained it. A uniform ρ means that it’s constant and can be left out of the integral. So it’s just -4πGρ on the left side. So I’m assuming then, that means the integral of d^3x is actually the volume of the sphere, right? So if you evaluated it, you’d get (-4πGρ)(4πR^3/3) = 4πR^2. You’d cancel the 4π on either side and be left with (-4πGρ)R^3/3 = R^2. Then you cancel again which gives you -4πGpR/3. That is equivalent to Newton’s equation. He got the wrong answer because he left out the initial -4π.

  • @tuutuutuuttuutuutuut2244
    @tuutuutuuttuutuutuut224410 ай бұрын

    life passes by as i try to understand this 'introduction'

  • @RodrigoRamirez-eq6gj

    @RodrigoRamirez-eq6gj

    8 ай бұрын

    This is an advanced undergraduate or early graduate course, to be able to grasp the concepts you need a foundation of college level calculus of several variables.

  • @veganbutcherhackepeter
    @veganbutcherhackepeter7 ай бұрын

    Leonard is my absolutely favorite contemporary physicist.

  • @beechersbrookpublishing
    @beechersbrookpublishing13 жыл бұрын

    Thanks for posting these lectures by Dr. Susskind

  • @rocksonasiamah9048
    @rocksonasiamah90486 жыл бұрын

    the presentation is well organised and the lecturer too, i think he deals well with his students. i like the way he handle question, is been enlightening lecture.on relativity.theory.

  • @hasanshirazi9535
    @hasanshirazi95355 жыл бұрын

    It is an honor to be taught by this gentleman. He has full command over what he is talking about. Thanks a lot Prof. Susskind.

  • @williammacdonald9870
    @williammacdonald98707 жыл бұрын

    I love this stuff I could listen to it all day

  • @BeardedDragonMan1997

    @BeardedDragonMan1997

    4 жыл бұрын

    PRANK GONE WRONG

  • @horseandcart5978

    @horseandcart5978

    3 жыл бұрын

    So could i. But i still wouldnt understand

  • @VixenEmpress
    @VixenEmpress8 жыл бұрын

    I want this guy as my professor.

  • @VixenEmpress

    @VixenEmpress

    7 жыл бұрын

    Haha... I'm a MSc student now and I'm planning to apply for my PhD. But I'm not a physicist, so he won't be my professor either way I look at it.

  • @test143000

    @test143000

    7 жыл бұрын

    not a problem - 75 000 USD per year and you in Stanford.

  • @closetedmilenialschizopers8734

    @closetedmilenialschizopers8734

    6 жыл бұрын

    If you continue watching this series... Than he is your prof.

  • @bl4z3_kanazaki

    @bl4z3_kanazaki

    5 жыл бұрын

    Is he still teach at Stanford, I really want to meet him, just once time =)

  • @d1psh1tc1ty

    @d1psh1tc1ty

    2 жыл бұрын

    You're not alone.

  • @HariprashadRavikumar
    @HariprashadRavikumar8 жыл бұрын

    it is my first mathematical lecture on general theory.... its very use full to me..😊

  • @BeardedDragonMan1997

    @BeardedDragonMan1997

    4 жыл бұрын

    PRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONGPRANK GONE WRONG

  • @swamijee
    @swamijee5 жыл бұрын

    Dr Susskind is a national treasure!

  • @swamynyc
    @swamynyc6 жыл бұрын

    What an amazing lecture!

  • @ralfg9194
    @ralfg9194 Жыл бұрын

    I recommend to read Professor Susskind's books as well (the Theoretical Minimum Series), in my opnion before looking the lectures. I t is a big luck that a first class, premium, five star scientist with such a reputation obviously has fun and an excellent ability to teach his stuff. Thank you for making this publicly available. Kind regards from Germany!

  • @shanansari8315

    @shanansari8315

    Жыл бұрын

    Bro I am read

  • @shanansari8315

    @shanansari8315

    Жыл бұрын

    Bro I am read

  • @muaztrek
    @muaztrek14 жыл бұрын

    Thanks to KZread and Stanford for posting these awesome videos :-)..........really worthwhile!.....oh and thanks to Prof Susskind for his lectures

  • @TarunKumar-sn9jw
    @TarunKumar-sn9jw9 жыл бұрын

    for the field to be inside on the left hand side it should be-- (-4/3 πR^3 4πρG)=4πR^2 A(perpendicular) then the missing pi can be located and the equation will become appropriate

  • @deadmeat1471

    @deadmeat1471

    8 жыл бұрын

    +Tarun Kumar the field is worked out by volume? I thought surface area;4pir^3(as he explained it)

  • @markcarbonaro70

    @markcarbonaro70

    8 жыл бұрын

    +deadmeat1471 p = m/v m = pv v_sphere = (4/3)πr^3 m = p((4/3)πr^3) For the equations to be consistent with each other, the "m" on the right board should be able to be replaced with the "pv" equivalent expression above, resulting in "A_perp = -(4π*r^3*p*G)/(3*r^2) = -(4π*p*G/3)*r" but instead the left board only shows "A_perp = -(p*G/3)*r". That's where the 4π is missing on the left (assuming the right was derived correctly)

  • @qwerty687687

    @qwerty687687

    7 жыл бұрын

    The error was in the right side of the equation on the left board. He equated A_perp*4pi*R^2 with the total mass inside the sphere (multiplied with G) and then expressed that as the volume of the sphere times the mass density. The correct way to apply Gauss' theorem would have been to equate the left side of this equation with the volume of the sphere V times the divergence inside, which is according to Gauss' law -4pi*rho*G. Thr final equation looks like this: A_perp*4pi*R^2=-4pi*rho*G*V and using V=(4/3)*pi*R^3: A_perp*4pi*R^2=-4pi*rho*G*(4/3)*pi*R^3 which has an additional factor of 4pi on the right side.

  • @clickaccept

    @clickaccept

    6 жыл бұрын

    deadmeat1417 use "dimensional analysis" to know you are wrong here. 4pi is dimensionless, so 4pi r^3 has dimension (length)^3. So its a volume, not an area.

  • @CollegeBoardSucks
    @CollegeBoardSucks12 жыл бұрын

    These lectures are incredible.

  • @grimzsirrano2464
    @grimzsirrano24647 жыл бұрын

    My maths is so damned rusty..Yet, Professor Susskind makes lecture's substance sound very easy... Thoroughly enjoyable and interesting stuff.

  • @ahmedsaadblackstar

    @ahmedsaadblackstar

    Жыл бұрын

    ٩ة٩٩خخت٩نت٩ةنك٩٩٩و٩٩٩خ٩٩٩٩٩٩ة٩و٩٩٩٩٩٩٩٩ة٩٩ت٩و٩٩٩ وننتظرن وون تت٩ ت٩ ن تت ٠ت ٩ ههههه ٩تو ت٩ خ٩ةتة٩ تت تتت تنخ٩ اه ٩٠نحت اه ٠ون٠٠ تت نن ٠٩٩ت٠٩ت نن نت٩ت٠تن٩٠٠ ٠ن٩٩٠ ٠ون٩

  • @austinfahrenheit3191
    @austinfahrenheit31918 жыл бұрын

    It takes an incredibly well prepared lecturer to throw out derivations on demand.

  • @RexGalilae

    @RexGalilae

    7 жыл бұрын

    Austin Fahrenheit or a very smart and passionate one

  • @Saintmadman

    @Saintmadman

    7 жыл бұрын

    not discredit Pr Susskind here, but anyone with basic school knowledge about differentiating could do derivations

  • @austinfahrenheit3191

    @austinfahrenheit3191

    7 жыл бұрын

    To follow them and understand them yes, but to remember where the equations came from takes an incredibly well prepared lecturer.

  • @qwerty687687

    @qwerty687687

    7 жыл бұрын

    I suspect Austin is talking about derivations of phyical formulae not about derivations of mathematical functions a.k.a. derivatives.

  • @paulholsters6430
    @paulholsters64303 жыл бұрын

    Thanks very much for this lecture.

  • @TheGreenCommunity
    @TheGreenCommunity14 жыл бұрын

    i absolutely appreciate your videos they are amazingly useful

  • @justushall9634
    @justushall96345 жыл бұрын

    At 1:13:13, it givs x = (1/2)g*t^2 as a formula for position of a (uniformly) accelerated object. That formula is only strictly applicable if the object started out at rest.

  • @kingoffire9373
    @kingoffire93735 жыл бұрын

    I'm not a student, I am just fascinated with physics and I love watching these to try to learn anything I can. Very good lectures! Is cosmological constant sort of like the inverse of gravity or something? Gravity is very weak but gets very strong with mass, cosmological constant is very weak but gets very strong with distance. So, in order to live in a universe (or to find ourselves in one from the anthropic principle) in which matter is being held together due to gravity, you would ultimately have to have the repulsion, otherwise it'd collapse on itself, and as the universe gets bigger and bigger, faster and faster, the surface area and distances of it is larger therefore enacting the cosmological constant to grow larger? Does that have anything to do with the formation of voids like Bootes void? To me it seems like that's why you get a filament or sponge like structure if you could zoom out on the universe as a whole.. all of the mass coalescing into valleys of spacetime, and voids bubbling up in relatively empty regions, which pushes matter out toward the valleys? Sorry, I'm sure these are really dumb questions, just trying to figure it out!

  • @itchyandscratchy7350

    @itchyandscratchy7350

    2 жыл бұрын

    I don't know, but I think that he said dark energy is a constant, so it doesn't get stronger.

  • @Vandalgia

    @Vandalgia

    2 жыл бұрын

    @@itchyandscratchy7350 The cosmological constant would get stronger as the time passes, I think Prof. Susskind explained it pretty clearly in the beginning. Also, it's not really getting stronger by the distance but due to its extremely small value, the equation would only sums up into a considerable number when it's multiplied by a huge distance, hence it only matter when you accounted the entire universe for it, but not so much in an astronomical scale or even in global scale. Calling it an inverse gravity is pretty much inaccurate because it's not exactly a force. Let alone a force that repulse each matter or particle from each other, it's something that drive the particle grow apart from each other.

  • @powahfulgameplayer

    @powahfulgameplayer

    2 жыл бұрын

    @@Vandalgia 6:20 Professor Susskind tells that the theory on the "Big Rip" describes the cosmological constant to be time-dependant, therefore growing with time. As Professor Susskind reminds, however, that is not true ; the theory on the "Big Rip" violates all principles of physics, and so it is not true based on the given principles of physics. I hope that clarifies Professor Susskind's point about the constant.

  • @Vandalgia

    @Vandalgia

    2 жыл бұрын

    @@powahfulgameplayer Yeah, "stronger" might not be the correct word to describe this. As you stated it, it's more like, it changes as the time passes.

  • @philgenz1
    @philgenz110 жыл бұрын

    Just love this guys voice and accent

  • @bennubyrd
    @bennubyrd Жыл бұрын

    Thank you Stanford!!

  • @JKARSKYFULL
    @JKARSKYFULL14 жыл бұрын

    Thanks a lot to Standford University, it's dificult to find the RG theory... thanks from Peru. Greetings

  • @maxwellsequation4887
    @maxwellsequation48873 жыл бұрын

    35:08 Fatality

  • @ajinjoyacdc
    @ajinjoyacdc9 жыл бұрын

    Session starts at 14.20

  • @BeardedDragonMan1997

    @BeardedDragonMan1997

    4 жыл бұрын

    PRANK GONE WRONG

  • @maxwellsequation4887

    @maxwellsequation4887

    3 жыл бұрын

    14:20

  • @rigoletocriptografado401
    @rigoletocriptografado4016 жыл бұрын

    Best course ever

  • @greg55666
    @greg556667 жыл бұрын

    That disagreement from 45:00 to 52:00, the student was 100% right, the professor got it wrong. He left out a factor of 4pi from the right hand side. Gauss's Law&Theorem state that Aperp*surf. area == -4piGM. So, at 45:00, the surface area is 4piR^2. And the mass of the sphere is the volume of the sphere * rho. The volume of the sphere is 4pi/3 * R^3. Plug all that in, you get: Aperp * 4piR^2 = -4pi * G * 4pi/3 * R^3 * rho. See the problem? When he wrote it down at 45:00, he forgot the first 4pi. He wrote down simply -GM rather than -4piGM. The student was right. After cancelling the 4pis from each side, you end up with: Aperp * R^2 = -G * 4pi/3 * R^3 * rho. So, Aperp = -4pi/3 * rho * G * R. If you changed that back to mass instead of rho, you'd get back to the original Gauss equation: Aperp = -GM/R^2.

  • @dylanhaymore608

    @dylanhaymore608

    6 жыл бұрын

    greg55666 That is correct. The student was right to be confused by the result Dr. Susskind came to on the left board because M=V*rho. For A perp = -MG/R^2 as on the right board the equation should read -{[(4pi/3)*R^3]*rho*G}/R^2. The (4pi/3)*R^3 is the volume of the sphere so when you multiply the volume by rho you get Mass or M=V*rho. Now all you need to do is substitute V*rho for M in the equation A perp = -MG/R^2 and cancel out the R^2 in the denominator with the R^3 in the numerator. That leaves A perp = (4pi/3)*rho*R*G. I think the confusion here is that the student asking the question had no idea how to articulate the correction he was attempting to point out. Had he been able to say "I can't seem to make the 4pi cancel out like you did due to the 2 equations you set up not being equivalent between the left and right boards. I think you unnecessarily added a 4pi to the L.H.S of the equation on the left board." then I think Dr. Susskind would have immediately realized the error and corrected it. The fact that there were so many conflicting voices in the room and nobody was making any sense led him to just leave it as it was.

  • @paulodonnell753

    @paulodonnell753

    11 ай бұрын

    @@dylanhaymore608 in student’s defense, he was constantly interrupted by sycophants. I’ve watched this maybe 10x trying to find the error. These posts helped Ty

  • @dylanhaymore608

    @dylanhaymore608

    11 ай бұрын

    @@paulodonnell753 I'm glad I was able to help you understand. This material is already difficult to learn so it's even harder to notice when there are errors from the instructor. Good luck on your journey for knowledge!

  • @tiger4627
    @tiger46273 жыл бұрын

    Time 50:00 min 4π is also there in the formula on right side when particle is inside sphere

  • @ilovetibees9389
    @ilovetibees93892 жыл бұрын

    good lecture

  • @gumbilicious1
    @gumbilicious111 жыл бұрын

    the description has: "discusses dark energy, the tendency of it to tear atoms apart" Susskind would be so pissed. He only spent about 15 minutes of the class explaining how unlikely it is for dark energy to rip apart atoms.

  • @itchyandscratchy7350

    @itchyandscratchy7350

    2 жыл бұрын

    Well tendency can mean tendency not to. Still, kind of misleading.

  • @AndrewThomasBlake
    @AndrewThomasBlake11 жыл бұрын

    Thanks for taking the trouble to clear that up for me.

  • @aliasradius
    @aliasradius15 жыл бұрын

    I tend to believe that the Felix Bloch professor of theoretical physics at Stanford University and his considerable contribution to string theory probably deserves a little more respect then that.. it is a privilege to watch this and thanks to him for his dedication to education.

  • @noelgrade
    @noelgrade14 жыл бұрын

    It is the sin(x) = 2MG/Rc^2 with x=2MG/Rc^2 that is used for the aproximation, also there is other aproximation, that for the elapsed time delta t, it is taken as the horizontal component of speed of light is the same c, that can be appear as a logic circle (that is not), since for this is used the a posteriori known fact that the angle is too small, and in the former the use of values of G and c are used to aproximate sinx =x.

  • @justushall9634
    @justushall96345 жыл бұрын

    About 26:35 into the video, he mentions unit vectors. Good. A very useful concept.

  • @k.p7873

    @k.p7873

    5 жыл бұрын

    😂😂😂😂😂

  • @SuperDynamite666
    @SuperDynamite66610 жыл бұрын

    Dr. Leonard is enjoying himself when students question him.

  • @quantomic1106
    @quantomic110613 жыл бұрын

    It just make me smile every time Prof. Susskind call the white board "black board". Other than that he's such a great educator. I wish i can attend his classes one day.

  • @meena2r
    @meena2r12 жыл бұрын

    thank u so much for the videos..:)

  • @EVANGELOSS54
    @EVANGELOSS548 жыл бұрын

    the correct formula for the acceleration inside a body is a(R)=4*π*ρ*R/3 , the 4*π should exist on the formula @46.27

  • @copyplant
    @copyplant11 жыл бұрын

    The 4pi is lost when he subs into Gauss's Theorem at 44:43. The right-hand side was previously calculated to be -4piGM (at 38:55), but he only subs into -GM, losing the 4pi.

  • @Al-cynic
    @Al-cynic Жыл бұрын

    good to see math kids all disagreeing with each other and one of the worlds best physicists, Gives innumerate biology students like me, hope!

  • @Gcock
    @Gcock Жыл бұрын

    Unbelievable. I have had very little formal education, a lifetime of professional experience traveling and living around the world. Mind blowing knowledge - FOR FREE - presented by a world class professor. It's troubling KZread algorithm does not push this content and knowledge More; esp the younger generation. I remember visiting a tiny all girls(K-8th) school started by Irish nuns over a century ago in Peshawar a few years ago; an entire classroom of 6th grade girls were doing Calculus on a true blackboard. I didn't understand a lick of it. Mean while in US, my 5th grade son has not come near Algibra much less Calculus. I'm not complaining, just comparing. Kids living in extreme poverty in a extremely dense ancient city, non stop extreme violence all around, yet they can focus their young minds to unbelievable levels academically. Our kids are distracted by countless electronic devices, social media, video games. Yet it is on those devices and media that you can find a world class education 🤷‍♂️.

  • @h.rkatyayan3989
    @h.rkatyayan39893 жыл бұрын

    Inspiring

  • @LapinPete
    @LapinPete14 жыл бұрын

    Must be quite an honor to actually be on lectures of that guy.

  • @markisus
    @markisus11 жыл бұрын

    The reason he messed up at 0:45:24 is that he is missing an additional factor of 4pi on the right hand side from Gauss' law: Del.A = G rho 4pi. Integrating this expression over the volume of a sphere leads to 4/3 pi r^3 * G rho 4 pi

  • @paulodonnell753

    @paulodonnell753

    11 ай бұрын

    Thank you!! The good professor goofed a few times in this lecture.

  • @karabesklow
    @karabesklow11 жыл бұрын

    To be onest he is real good teacher. Turning complex things to real simple (making it dumb) is high skill. Explaining something complex in a complex way is easy. What hard is turning complex things into a "cosmological constant" dumb level,requires high amount of experience and capeability. Btw : the students having problem with perpendicular A is the mistake that the both examples are different and the perpendicular A is example specific. there are two different A not equal :)

  • @MS-cj8uw
    @MS-cj8uw7 жыл бұрын

    Thank you professor..... One question was : why the effect of mass outside the Gauss surface inside the spherical mass be neglected or canceled ....my answer is I think that the mass is not neglected as you see the density of the field (the gravitation density g) be reduced by reducing the (r) to becomes zero in the centre of sphere which means that the effect of the outside mass which also cause (g) can be considered as superposition summation for the (g) vector at the center and that summation becomes zero when (r) become zero so the disappear of the (g) in the center due to the opposite directions of (g) , from the general relativity point of view also we can understand that the distortion of the metric tensor curvature outside the mass (density of energy) is totally different than when it passes through the it ...thank you

  • @Metallurgist47
    @Metallurgist478 жыл бұрын

    At 1.18 Susskind describes how a light beam would cross an accelerating elevator -- noting that the observer in the elevator would see a downward curving light beam (and an external ,stationary , observer , presumably seeing the light beam travelling straight and horizontally ). And yet had the elevator been travelling at a constant speed (SR), the observer in the elevator would see the beam travelling horizontally within the elevator, and the external observer would see it travelling diagonally upwards. Why does the external observer ,say, see the light beam being affected by the elevator's frame of reference in the SR case , but not in the GR case. ?.

  • @jsw58240

    @jsw58240

    8 жыл бұрын

    +Metallurgist47 If I understand correctly the difference is in the original vector of the light. With the accelerating frame the assumption is the beam is emitted at the same time the acceleration starts and so it's direction is horizontal. In the constant velocity case, since the velocity is constant, you have to assume that the elevator is in motion at the beginning of the experiment and the beam is emitted from a source inside the elevator and therefore it starts with the upward component already. Also, the curvature is only seen by the observer inside the elevator. To someone outside it travels perfectly horizontally.

  • @csmcmillion
    @csmcmillion12 жыл бұрын

    @tonyxon That little round button at the bottom of the Flash display does something called "seeking". Try it out.

  • @enaud847876
    @enaud8478767 жыл бұрын

    Hi, wonderful video. but a question: there is a book for follow this lectures? i want to have also a book for Einstein relativity Special and general. Thanks all and regards from Italy :-)

  • @Saintmadman

    @Saintmadman

    7 жыл бұрын

    there is one called Special Relativity and Classical Field Theory: The Theoretical Minimum . It is coming out in September. Susskind wrote other books such as 'Quantum Mechaniics'

  • @mohammedtalibmosa7344
    @mohammedtalibmosa73448 жыл бұрын

    thank you

  • @caninemonkey8488
    @caninemonkey84887 ай бұрын

    If we could have the moons lack of gravity with the Earths atmosphere. Thanks for teaching and posting this!

  • @pellep5288
    @pellep5288 Жыл бұрын

    I accedentally fell asleep when watching youtube, woke up and had watched the whole lecture one and was at the end of this one. Am I gonna be a genius now?

  • @zack_120
    @zack_12011 ай бұрын

    37:09 - a piece of art work: a little sitting bear he has candidly drawn 😊

  • @charliepontecorvo
    @charliepontecorvo13 жыл бұрын

    Take note that in the discussion of the gravitational field at some radius R inside the earth taken from the center of the earth, that Leonard had dropped a 4pi. Perhaps you may have caught this. So, the g field at radius R inside the earth is actually: G*p*pi*R*4/3

  • @ajnedable
    @ajnedable11 жыл бұрын

    Exactly!

  • @thealbaniandude1997
    @thealbaniandude19974 жыл бұрын

    I thought this was the final part of the explanation as I had simply opened this video, not the playlist, and KZread hadn't recommended any part 3 or bigger on the suggestions. :(

  • @Jipzorowns
    @Jipzorowns12 жыл бұрын

    alright, thanks mate! :)

  • @ShenghuiYang
    @ShenghuiYang4 жыл бұрын

    It is impossible to overrate the quality of this lecture.

  • @ashkara8652
    @ashkara86526 жыл бұрын

    BTW the last half hour of this video is freaking cool.

  • @metazero911
    @metazero91112 жыл бұрын

    Awesome....physics for free

  • @Treknologist
    @Treknologist11 жыл бұрын

    45:20 He remembers the G but forgets the original 4pi from Gauss' Law.

  • @maxwellsequation4887

    @maxwellsequation4887

    3 жыл бұрын

    45:20

  • @BenjaminSteber
    @BenjaminSteber12 жыл бұрын

    Yeah. Well put. Spherical space about the center of mass is the reasonable conclusion. I forgot that the mandatory requirement that all mass be contained within R of the center of mass.

  • @nithinjoseph264
    @nithinjoseph2643 жыл бұрын

    52:42 The equations in the 2 cases don't match coz a 4pi was accidentally left out which comes from the Gauss's Law

  • @feynization
    @feynization12 жыл бұрын

    @memyself1125 No. Satelites use it and Particle accelerators use it but until you get to speeds of (lets say 10,000 miles per hour) you do not use it. That being said there is relative motion, which is helpful to the layman, but not a necessity.

  • @nberedim
    @nberedim11 жыл бұрын

    Well, actually when the gravity field equation is derived, we assume a test particle with mass m different than zero. When the m term appears on both sides of the equation, we divide by that (thus it must be different than zero). Therefore it is counter-intuitive to suggest that gravity has the same effect on a zero mass particle. On the contrary according to Newton the gravitational force exerted on a zero mass particle is zero.

  • @bleachbucket9440
    @bleachbucket94405 жыл бұрын

    Wow such understanding and superior explanation, compared to my "professers"

  • @tim57243
    @tim572434 ай бұрын

    Is it a coincidence that the operation of applying an operator to a function looks the same as the operation of multiplying two values? Both are written with simple concatenation. Maybe a number is identified with the operation of multiplying by that number? It could also be identified with the operation of adding that number, and I don't see a principle that says to pick one over the other.

  • @nurlatifahmohdnor8939
    @nurlatifahmohdnor89392 жыл бұрын

    Time = vector quantity (foward) Clockwise = could be moving to the right like of the normal clock we have but some people do sell clock that move to the left. As long as it is 360 degrees. So I think there is nothing like 'anti' Ant = se-mut A-rah = direction Jam = clock What is wise? Page 1375 -wise adv combining form. 1 indicating direction or manner: clockwise; likewise. 2 with reference to: businesswise. [OE -wisan (italic); see WISE2] wise1 1 2 prudent; sensible. 3 4 5 6 7 Arch. possessing power or magic. 8 9 10 wise2 n Arch. way, manner, fashion, or respect (esp. in any wise, in no wise) [OE wise (italic) manner]

  • @Theninjagecko
    @Theninjagecko2 жыл бұрын

    Maybe particles are more pushed together than pulled to each other and that's why it increases as you pull them apart, space "pressure" so to speak pushing them together.

  • @p0888557
    @p088855711 жыл бұрын

    Would it be correct, trying to combine both equations (inside and outside the planet) to consider the planet as a point in the center with punctual weight equal to the weight of the section of distance less than ||x|| and a shell acquipped with the mass of the section consisting of point at distance between ||x|| and R_planet ?

  • @BenjaminSteber
    @BenjaminSteber12 жыл бұрын

    Since the divergance of the field equation is calculated in terms of Pi does that mean that the mass density can only account for spherical space?

  • @peteschupp4545
    @peteschupp45454 жыл бұрын

    So there is a newtonian aquivalence Principle( if an object gets pulled by a bigger mass the acceleration is not dependent of the mass of the smaller object) and Einsteins aquivalence princple( when you accelerate a rocket with 9,81m/s^2 it Feels like earth‘s Gravity Field for someone in that rocket )?

  • @NaveedImranS
    @NaveedImranS14 жыл бұрын

    Thanks to Google, KZread and the internet technology researchers who made this possible to watch these videos. Otherwise I had no chance to see this lecture series.

  • @Ah4b
    @Ah4b10 жыл бұрын

    Nope, there was a 4pi missing. Should be for R>R_0: A=-MG/R² R

  • @dimitriosagos5631

    @dimitriosagos5631

    2 жыл бұрын

    00 lol you can 00 lol 00 00 loll 00 like 00000000000000000000000)00 0000lolllll

  • @plexx731
    @plexx7312 жыл бұрын

    this are these these vids that you see in your watch history when you wake up

  • @milesdavidsmith
    @milesdavidsmith6 жыл бұрын

    But does that suggest that the divergence is a relative scalar?

  • @hattielankford4775
    @hattielankford4775 Жыл бұрын

    14:03 I liked where you were going. 🤷‍♀️ Nicely handled, though. Every semester, some play on relativity, I assume.

  • @JohnJohn-zg9hh
    @JohnJohn-zg9hh3 жыл бұрын

    I suppose that this is second year subject, but Student are asking question like they did not complete any university maths, or physics before. Gauss's Law is and Gauss theorem is usually first year mathematics, and they usually had to overcome difficulties with new concepts.

  • @tagorechandmeah425
    @tagorechandmeah42511 жыл бұрын

    Yes people are asking question like they don't know what they are talking about. And his style is like he is teaching for those who already have some knowledge.

  • @MrAlutchman76
    @MrAlutchman7612 жыл бұрын

    @stenniswood if space itself is converging into point masses then where is it going to? Another universe? As raw material for the expanding edges of our universe?

  • @phpxs
    @phpxs12 жыл бұрын

    Well, rho = m/V would be the case if the mass if uniformly distributed in a given volume. If the value of rho depends of the chosen volume we have to write rho = Delta m/Delta V. I think this becomes more obvious if you take the limit Delta V -> 0. Then, the differences become differentials. rho = dm/dV => dm = rho dV Integrate over a given volume to get the mass included in this volume. M(in the chosen volume) = Integral{rho dV} . and rho in general could be a function of V.

  • @kmmt30
    @kmmt3012 жыл бұрын

    Is the lamda increase due to the dark energy that is added through distance

  • @NaveedKhan-dg5bv
    @NaveedKhan-dg5bv7 жыл бұрын

    but when we replace density by M/v= mass to volume ratio thn we get A is inversely proportional to R (not directly, plz correct me if i m wrong

  • @nejzdibotlane107
    @nejzdibotlane1077 жыл бұрын

    Am I the only one that get's extremely satisfied when he erases every marker trail instead of just leaving it be

  • @auntiecarol

    @auntiecarol

    6 жыл бұрын

    You are not alone.

  • @MrDiamond573
    @MrDiamond57312 жыл бұрын

    he is a very knowledgeable

  • @nibussss
    @nibussss2 жыл бұрын

    Frame of reference connected in time.... Electron jumps..position superposition... Parallel so ....electrons are paralle to each other...not disappear gband appearing another place.. Photons bend because of mass down?