Einstein's General Theory of Relativity | Lecture 7

[reimannx33]

urrgh..that annoying guy again arguing about a Coulomb of charge(1:30:00)....-he needs to just shut his mouth ...

[adelle0001]

nice one! very informative

[agapitoflores001]

He is an Einstein look alike, only with less hair.

[metalfreek105]

Regarding discussion at 1:27:00, if you isolate 1C of charge than as Professor said have to get out of the room immediately. The thing about capacitor is that both +ve and -ve charges are very close to each other so the net effect cancels out.

[bobcrunch]

The teachers with deep understanding of the material explain things so simply. A grad student would have filled the board with gibberish. If you really know something, you should be able to explain it to your mother.

[weweallthewayhome]

the flux capacitor!

[warex3d]

6 no entendieron que son las curvas.

[lordwhiteblueeyes]

@warex3d esta dificil entender si esta en ingles ademas su traductor es una basura

[kristylvsjets]

layman's terminology could have been better explained. For instance; sprirograph is a good example. Create 3 of the tape together and you have a good visual example. Then you just need to factor in all other or I should say label what each step represents and there you go. Well there is a little more to factor in, but I am exsplendidly talking about the beginning .5 of this video.

[calebp9503]

dude at 1:27:06 got his panties in a twist over the amount of a coulomb. lol

[StudyAcademic]

what is ricci curvature?

[csmcmillion]

@StudyAcademic Google "Christina Ricci pics" and you'll see.

[melliuzza]

jay z

[fuckshitass911]

1:26:00

i bet the guy was a troll himself on the internet.

[fuckshitass911]

@fuckshitass911

troll physics FTW

[wizardofmadness]

geodesic = mohamed doesn't allow mountains to move you

[newtonswig]

I like these lectures but he kind of dodges the 'intuition for paralell transport' question. For the record, in the Riemannian setting I found it useful to think about it as 'keep the inner product with the coordinate vectors (v^i e^j g_ij) constant'. Of course that's totally circular if you want to be rigorous- but hey, maybe someone else will find it handy...

[Steinbiten]

hes a sith lord

[Aure217]

Does anyone know where one might find lectures on geometry? Like, differential geometry I guess, that underlies the theory here.

[aridalo10]

I'm from a Spanish speaking country, I would like someone to upload the English subtitles to this video. I would make it easier to understand.

Thanks so much

[abc75]

This lesson is particularly outstanding!

[beejusbeejus]

I...

[weweallthewayhome]

Culombs have so much to do with gravity you know.

[ayadiv]

Does anybody know any Introductory Lectures on String-theory on youtube, like this on GR?

I've tries to find, but i can't...

[ExhumedANDConsumed]

@ayadiv There is a TTC introductory lecture series on String Theory (I have it, but haven't watched it yet). It is about 24 lectures. That is about all there is at the time I believe. Its rather expensive to buy but if your clever.....do I really need to state it? :D

[ayadiv]

Thank you for your useful advice!

Do you know any good introductory lecture notes on String theory?

[ExhumedANDConsumed]

@ayadiv Hmmm well my best guess would be the Demystified book on String Theory, dont get turned off by the title (Demystified) thinking it is an elementary introduction with very little math. The Demystified book on Quantum Mechanics and General Relatiivty are very in-depth mathematically and very nice reads. The Demystified String Theory book is on the internet if you want a nice ebook version, just google.

[ShootBigBird]

John Wheeler: Matter tells Spacetime how to curve, and Spacetime tells matter how to move.

The presence of mass bends spacetime (it doesnt actually bend; it creates the vectorized negative divergence field, lesson 3 I think) which naturally creates the geodesic pathways. Matter now has a force free ride, since the Christoffels (which represent the forces) travel along with mass inside the geodesics. This means NO INERTIA to change direction (relative to flat spacetime).

How cool is that?!?!?!

[ShootBigBird]

OH, just remember, spacetime doesnt actually curve. It is the geodesic which is curved (relative to flat spacetime) when it is in a field of negative divergence. The negative divergence is always perpendicular to the mass surface (uniformity reqd), so there is no bending of the vectors on the fieldexcept in frame draggingbut thats only when the mass is spinning.

[ShootBigBird]

Number of inputs for 4 dimensions is 256 BTW.

[ShootBigBird]

At 1:05 In order for the Riemann Tensor to be usable in GR, Ricci needed to make the derivatives vectors (back in lesson 6). Also, the Ricci Tensor came from the understanding of Maxwell's equations (and the Lorentz transformations) as he had transcribed them from English into Italian requested by Betti. The Ricci tensor needed to be vectorised, and could not be kept scalared (two x two coordinate planes). Gravity gets stronger closer to mass yeah?!

[letmechooseaname]

Just in case anyone's making notes... the symmetries of the Riemann tensor he notes actually reduce the number of independent components to 21 and there's an additional symmetry (Rabcd+Racdb+Radbc=0) that further reduces that number to 20

[kirankirtichauhan1]

@letmechooseaname ....I am making notes.Could you please shed some light on the derivation of the Riemann tensor ?

[letmechooseaname]

@kirankirtichauhan1 The symmetries of the Riemann tensor can be deduced in a very neat way by assuming that we can always transform to locally inertial frame. In this frame, the metric is the Minkowski metric and its first derivatives disappear. However, as the frame is only locally inertial, the second derivatives do not vanish. Therefore, the Christoffel symbols vanish but their derivatives don't. This leaves only the first two terms in the expression of the Riemann tensor.

[letmechooseaname]

@kirankirtichauhan1 The Riemann tensor may then be written as Rabcd = GAMMA abd,c - GAMMA abc,d = 1/2 * gal(gld,bc + gbc,ld - gbd,lc - glc,db)

From this, symmetries of the tensor are obvious : Rabcd = -Rabdc = -Rbacd = Rcdab and Rabcd + Racdb + Radbc = 0. Note that if Rabcd + Rabdc = 0 in an inertial frame then, as this is a tensor equation, it holds in all frames. So these symmetries are general. Hope this helps.

[thisiscowshit1001]

i've been trying to watch this but then my brain started to bleed. :)

[Hornet85]

I've seen this guy in a documentary before, i can't exactly remember which one it was... i think it has something to do with string theory...

[LiuKang1080]

hes one of the fathers of string theory, and contradicted Stephen Hawking's theory on black holes

[kevaughanshiu]

man i'm in grade 10 and ... this is too much D:

[marsCubed]

kevaughanshiu, Try Berkley university channel and look for lectures by Professor Richard Muller. They will ease you into many of these concepts in a less mathematically intense way. the series for future presidents series is excellent.

also go through some of the other lectures by Prf. Susskind. many talk about related concepts, viewing many will eventually get things to stick so that you can make progress. These are difficult concepts, but we can think them with practice and maths.

[kevaughanshiu]

thanks for the reply.

Let's just hope i can understand by the time i'm in university

[kirankirtichauhan1]

@marsCubed ...I have gone through all of Prf Susskinds Lectures except the last 5 on GR and have made extensive notes. I need to improve upon my understanding with more material; lecture videos, books etc.I'll go through ucb .Thanks.Can you give some more inputs?

[marsCubed]

@kirankirtichauhan1

Books you may like to read which accompany many of these courses are

Black Hole War

The Cosmic Landscape

An Introduction to Black Holes

Personally I find that explaining what I have learned to someone else, helps to make the concepts stick. (even if they lose track of the finer points)

Other than that, scouring YT, especially the university channels, will yield more learning material.

I will PM you if I find something of particular interest.

[kirankirtichauhan1]

Thanx a ton!.Explaining would to me mean sharing of meaning.If its ok with you can I share with you my understanding?

[HMiste]

I feel your pain. I'm in Year 9, and the basic idea I have of the Theory of Relativity is that it created E = mc2 (which I could be COMPLETELY WRONG ABOUT), but to hear this man talk about it as if it was something he could talk for hours about subconciously proves that he's a genius in this world.

[malesaccio]

I disagree with the last comment: I'm finding the entire course very clear so far!

[crusadersoldier]

This man is a very bad teacher, he just is not able to explain the subject in an understandable way. He is making it sound more complex than it actually is (not that I want to imply that relativity is easy to understand). Standford sucks if it cannot afford better teachers!

[cursorminer]

excellent... it's amazing that you can learn this stuff at home so easily. Well not easily but you know what i mean...

[rocxtar19]

its great im so glad i just found this. I wish they put this on TV!!

[kirankirtichauhan1]

Well........at least you get a chance to learn..........but one does require other supplementary sources to enhance the understanding

[floopsie666]

@cursorminer if only it was easy T_T

[KinStrategy]

This is interesting.

[izchan012]

good

some lectures are here..

tnx...

[wiiredjr]

My brain... >_>.

[sealawyer2009]

Lessons 8 and 9 are on iTunes. Why not here?

[regshit]

could you PLEASE upload the next lecture ? There must be at least one more

[sealawyer2009]

For those who cannot wait, lecture 8 is on iTunes.

[Prearius]

Thank you Pr. Susskind for these amazing vids!So generous of u to share ur knowledge with the world. We need more people like you.

[samgee2007]

this guy is smarter than einstien