Special Relativity | Lecture 8

(June 5, 2012) Leonard Susskind covers more topics in electromagnetism and relativity, including dynamics of the electric and magnetic field and the related effect of charges on the electromagnetic field.
In 1905, while only twenty-six years old, Albert Einstein published "On the Electrodynamics of Moving Bodies" and effectively extended classical laws of relativity to all laws of physics, even electrodynamics. Professor Susskind takes a close look at the special theory of relativity and also at classical field theory. Concepts addressed here include space-time and four-dimensional space-time, electromagnetic fields and their application to Maxwell's equations.

Originally presented in the Stanford Continuing Studies Program.
Stanford University:
www.stanford.edu/
Continuing Studies Program:
csp.stanford.edu/
Stanford University Channel on KZbin:
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[@randymartin5500]

So far I have watched all 15+ hours of Classical Mechanics and I am hooked - I look forward to all of them in the appropriate order of subject matter since it looks like you need the math back ground of one to move onto the next- ie, Special Relativity then General Relativity then Quantum Mechanics then Cosmology etc... Such a considerate humble Professor - always taking a few minutes away from the material to go over some basic concepts such as the definition or a Curl and Divergence , which I am still getting familiar with even after the last of the Classical Mechanics lectures. Bravo Prof, Susskind!

[@FarFromEquilibrium]

if you can watch this entire vid in 2 hrs , and get it, that's amazing. I take notes and try to get a good understanding of what he says before moving on and it takes me about 4 hrs!

[@seaghanomodhrain7568]

Note the sign error in both the Maxwell equations with the curls. It means you won't get the continuity equation if you use the equations as written on the board.

[@DrDress]

40:00 Maxwells equations from the vector potential 56:00 Charge and current 1:15:00 Current and continuity

[@NazriB]

Lies again? Hello AMWF

[@PetraAxolotl]

At about 30:30, there should be another term, which is F_zx. It does not really matter at the end because L^0_x is zero. But logically in the derivation itself, F_zx should be there.

[@MrLethalShots]

There should also be an F^0z term when you work out the summation but then disappears because there was no E_z to begin with.

[@drummerboy91893]

What a lovely lecture with an aesthetically pleasing explanation of the j 4-vector, a derivation of two of Maxwell's equations, and a summary of the second half of Einstein's paper.

[@nullnull3109]

kurj

[@massimoacerbis8138]

This indeed the key point of special relativity Understanding properly what maxwell equations imply in terms of space and time measurement

[@YouGenie]

The coolness of this lecture is in the t-shirt. Some great wonders of science at the place and time denoted by a number of creative minds.

[@mikikaboom9084]

1:04:58 I love how he just talks, while the dude is installing him a microphone.

[@dav2021]

766

[@dav2021]

3765783

[@jejjaktheone6010]

e

[@jejjaktheone6010]

Ur

[@jejjaktheone6010]

Rue

[@ritikpal1491]

Wont the 4-vector j change too when you look at it from a moving frame?

[@abhaymenon1667]

why does have the signs of Maxwell's equations changed? I'm talking about the ones with the curls. @50:51

[@Hippoman141]

Awesome! Thanks Stanford!

[@bunklypeppz]

In the stationary frame for the electron is there supposed to be a component of the magnetic field: B_y/(1-v^2)^.5? That's what I seem to get when to transform from the lab frame to the electron frame, but that seems to contradict the notion that there is only an electric force effecting the electron in it's stationary frame. Isn't the component that he worked out on the board around 32:00 supposed to be the only component of the fields in the electron's rest frame?

[@tedsheridan8725]

Yes, there is a magnetic field in the wire's frame as well. But as the velocity of the electron is zero in this frame, there is no contribution to the force by the magnetic field.

[@JWY]

I can't show charge conservation unless j is equal to Curl[B] minus partial E with time. White board has Curl[B] + partial E with time.

[@zphuo]

Before 34:00, how to Lorentz transform the EM Tensor!! @1:20:00 Charge conservation (Local conservation) will cancel out the B part of Maxwall's 4th formula and just leave the E. But what is the relationship between A and J? They are 4 vector here.

[@GuillermoValleCosmos]

I think that at 16:08 he got the signs of the Electric fields wrong (Look here en. wikipedia. org/ wiki/Lorentz_force where they use the same metric signature, other pages). I also think that's what made his Faraday's law equation have the sign wrong.

[@GuillermoValleCosmos]

Same thing over here! But it's so worth it!

[@KipIngram]

1:45:55 - Dr. Susskind, you're teasing us. It's almost mean to dangle this interesting stuff about how maybe magnetic monopoles aren't forbidden after all, and then provide no satisfaction. :-) Does anyone know if Dr. Susskind discusses this further in any of his other lectures?

[@JWY]

I proved charge conservation follows. I just copied the white board into Mathematica (8 lines of code plus 1/3 cup coffee) and pressed enter - I've got externalized understanding.

[@roygavangalvan7976]

Gracias por subir este video .

[@nomizu_feldbach]

Good video, but there seems to be a sign error with Faraday's law.

[@spagetychannel5070]

So the fact that the electric and magnetic fields each have 3 components is just a coincidence? In n+1-dimensional spacetime, the electric field would have n components and the magnetic field would have ½(n²-n) components, assuming they both come from a vector potential.

[@aqouby]

Cold fusion, sacred geometry, illuminati, electric universe, antigravity... Ah, solace in Susskind's videos. There are so many stupid things out there, thank god for real science being on YT.

[@karlakson9574]

Zfzfg SF goguf da gzyfi gigxofifzziizhas uzfifi sux gizgzgfczgggxiigggiguGgxgc I zug ugxyfgugigz chgog did giggitcGxxggizoz xgggfxggzgixzugg uggzgigiguzg ugitigixgxiixg ugi tg xizgxiy igzgzifdyggiigzgz ggizgx

[@ericzeigler8669]

Why does Leonard reject the Copenhagen interpretation of quantum mechanics? Didn't experiments prove that locality was an erroneous concept in quantum mechanics? He glossed over the student's challenge about locality.

[@vampyricon7026]

It was addressed in several lectures in the quantum mechanics course:theoreticalminimum.com/courses/quantum-mechanics/2012/winter

[@nurlatifahmohdnor8939]

Da-mar = resin (About wood.) Pin-tu ger-bang = gate Pin-tu = door Invar = Nickel + ____ Ka'abah. What is its height, width, length?

[@tobywhite1100]

He seems to give the right form of F in Lecture 6 (at ~45m) -- at least it agrees with lecture notes from other sources. FWIW, the correct move may be to flip the signs of the space-space components in both the covariant and contravariant versions of the F he gives (at ~15-20m) in this lecture.

[@DrDress]

Here is Einstains paper www.fourmilab.ch/etexts/einstein/specrel/www/

[@KipIngram]

1:15:30 - lmao... Dr. Susskind really loves to avoid writing stuff (let's take the volume to be 1...)

[@WorldBurial]

I don't think so. It's not really useless and there's lots of hours left to do other stuff.

[@marccatamio]

1:04:36 This is where he took of his jacket

[@jameshadaway8621]

10 years in 40 minutes. 😶

[@РодионЧаускин]

Harris Matthew Rodriguez David Lee Patricia

[@northpole7662]

66

[@AnuarPhysics]

I don't think so. I spend 1 hour daily watching these videos.

[@AnshulBhardwaj]

Guy who recorded all these lectures kzbin.info/www/bejne/gp_Wi5SFmKtkeNE

[@BladeRunerUnit99S]

\o/ me too !!! not at all !!!

[@ericzeigler8669]

Leonard should talk about the meaty principles when he teaches, leaving the details to another professor that doesn't make so many errors on the board. It is boring to hear him say so often, "Is that right? I think it's right. Maybe a sign change, anybody know?"

[@anklexpress]

this is generally how most theoretical classes work. the goal is not to track all the minus signs, but to illustrate the concepts of the derivation and help you work through the derivation with a sort of logic. Then typically your HW would be to prove taht following those steps, and tracking all the damn signs here and there, you actually get the proper correct final equation. At least from my experience in school. The details, as you put it, are actually for you to work out, not another professor, but I could see how it might be confusing if you were trying to follow the calculation along and not the ideas that that you from step to another

[@nicolatesla2]

Somebody is teaching quantum mechanics =))))

[@mrx666]

++!!!

[@JudgeRhadamanthys]

Is it pathetic of me to spend 2 hours of weekend time to watch this video?

[@BarriosGroupie]

No, having a curious brain is pathetic in the eyes of those without one

[@newtonrhodes7093]

This should be filed under religious studies.