Lecture 2 | Modern Physics: Special Relativity (Stanford)

[nirdeshreddy92]

thank u for the upload

[asilvescu]

He already mentioned that he is using units where c=1. so no mistake.

[canceodgr8]

dear all, THERE'S A MISTAKE MADE BY HIM AT 1.05 MIN..

d(tau)^2 isnt equal to dt^2-dx^2

but it is equal to dt^2 - dx^2/c^2

CHECK!

[TheFratmanbootcake]

@canceodgr8

There is no mistake.

He is working in units of c=1...

It's what most people do when working with relativity. For example, measure time in years and distance in light years, then the speed of light is 1.

[bbsonjohn]

@canceodgr8 You have just exposed your identity as an idiot, sir.

[SwanSongBlues]

Is anyone else frustrated because he never quite cleans the whiteboard perfectly before he starts a new set of equations.

[RBChoman]

It was not difficult to get the concept of fields, the Lagrangian, Euler-Lagrange equation and Principle of Least Action. Thanks! Now, Calculus and classical Mechanics make even more sense to me.

[perniciousnc]

i=7 hahaha

nice lectures thanks for sharing

[mysticlawlotus]

Classical field theory does not mean it comes from Greece! lmao. Brilliant.

[mysticlawlotus]

Can you rotate 2 pies right the way around in Minkowski space and end up with a smile on your face?

[tinsh0es]

Professor Susskind rocks!

[tomo25252]

He looks like Hendrik Lorentz himself.

[joppadoni]

these lectures are incerdible

[sandustanBrasov]

• SandustanBrasov

The Michelson-Morley experiments(1881) with the purpose to put in evidence the Earth movement face of one immobile ether, for too be taken as a reference system, had forever the same result. Thus the experiments had showed: 1).-that the ether is complete training with the mass and the Earth's atmosphere; 2).- and that our conception about ether as reference system is not right.

[sandustanBrasov]

• SandustanBrasov

The science has and history. In the Fundamental Principle of Democrit(470..380BC) it show:"From nothing nothing's born, nothing that exist can not be destroyed and any transformation consist from a reunion and separation...Out of atoms and ether. all rest is not otherwise than rationament and not exist...The spirit as well as the ether consist of a small and spherical atoms, very mobile, atoms that their movement form the phenomenon of life".

[sandustanBrasov]

• SandustanBrasov

It popularize the fantastical theories and stantardized theories with which it terrorize the inhabitants the Earth, after what Einstein with relativity theory had blocked the science of the century XX. Sptephen Hawking and roger Penrose had demonstrated in 1967 that the black holes proceed from the relativity theory. How it can conceive and it can say that the heart of the one black hole is a gravitational singularity whose volume tend to zero and whose mass tend to infinite?

[sandustanBrasov]

• SandustanBrasov

Through the relativity theory to Einstein of over century, it hold with strenght -as a conspiracy a general activity of intellectual stultify of the planetary population. from relativity theory proceed the notion of: singularity, Big bang, black holes and holes of worm. From 1905 and till now in 2011, the disciples of the Einstein, preach with contumely as scientific elements of high class these theoretical confusions, these absurdities from which they had made a business.

[ggankinboon]

I want to ask that why actual time= dt-dx??? According to the Twin Paradox... the traveler will have a slower time... if it is minus...then it will have a shorter time!!!!

[JoonasD6]

@ggankinboon The travereler will have spent shorter time, from his frame of reference. :)

[binaryblade2]

I'm curious how the principle of least action could produce a lossy wave equation.

[sriram92karthik]

Fantastic lecture

[jesuschristallin666]

yo, Susskind is the man!

[SuperSpinor]

Does anyone else feel like they are taking crazy pills? Around 1:10-1:15 he talks about what I call the 'stretch' of the spring. He says 'typically the energy is proportional to the square of the separation between the two mass points'. I just don't agree, it really is proportional to the 'stretch' from equilibrium. So, he makes a simplification that the equilibrium position is when the spring is of zero length! If you don't make that simplification then there are cross terms...

[bodeatibi]

@SuperSpinor

[TheBobathon]

@SuperSpinor Yes... the "stretch" is not √(Δφ²+ε²); it should be this minus the natural length of the string. To do it properly, you need to bring in a tension, T. Each spring is stretched by an amount T/k even at rest, so the natural length is (ε-T/k).

The "stretch" is ε√(1+Δφ²/ε²) - ε + T/k. If you do a series expansion, drop the higher order terms in Δφ²/ε², and drop the constant term (because it doesn't affect the equation of motion), you get U=TΔφ²/2ε.

[DarkShroom]

awsome lectures, worse q's i've ever seen though looks like a g

[NeoGenus1]

This stuff is helpful, I've only got this class 2x a week so any extra lecture I can get is just great!

[Chaos7703]

I particularly like 1:00-1:06 where he's talking about the differences squared in positions resolve to first derivatives (velocities) and the differences of those being second derivatives (accelerations). It gave me some cool visualizations of the interactions going on.

[awax10000]

A+ He is very good!