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.

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[randymartin]

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!

[seaghanomodhrain]

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

[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.

[drummerboy]

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.

[massimoacerbis]

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.

[ritikpal]

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

[abhaymenon]

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

[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.

[mikikaboom]

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

[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?

[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.

[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.

[nurlatifahmohdnor]

Da-mar = resin


(About wood.)

Pin-tu ger-bang = gate




Pin-tu = door


Invar = Nickel + ____




Ka'abah. What is its height, width, length?

[GuillermoValleCosmos]

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

[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.

[nomizu_feldbach]

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

[spagetychannel]

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.