Statistical Mechanics Lecture 8

(May 20, 2013) Leonard Susskind continues the discussion of reversibility by calculating the small but finite probability that all molecules of a gas collect in one half of a room. He then introduces the statistical mechanics of magnetism.

Originally presented in the Stanford Continuing Studies Program.

Stanford University:

Continuing Studies Program:

Stanford University Channel on YouTube:

[mashahomya]

35:53 magnets
39:53 - 42:34 questions
43:13 simple magnet model (№I with NO interaction between magnets, with external field)
46:55 general case. finding z and average energy E
56:46 m magnetisation defiition
59:53 - 1:06:48 questions
1:06:50 average energy E from z
1:13:24 magnetisation
1:15:00 1d ising model model (№II WITH interaction between magnets and no external field)
1:15:00 a bit of history
1:16:15 model discription
1:24:42 on symmetry

[Unidentifying]

Thank you Stanford, Susskind, Internet, Youtube and myself for watching.
Keep spreading the information and awesomesauce.

[sylarfeet]

Thank you Stanford University for all your wisdom and creativeness and your team of world class professionals professors that made it all come true. The answer is @nano second…..

[liveCha]

Poincare: 29 April 1854 – 17 July 1912
Boltzmann: February 20, 1844 – September 5, 1906

[KipIngram]

30:00-ish - I love how we get to hear the questions, and Susskind's answer to them. But on some occasions someone take the whole discussion off into left field, and Susskind is too nice to cut them off. Those bits should be edited out; they don't really contribute anything.

[FarFromEquilibrium]

@ 14:50 that is the most interesting q&a I've ever heard in one of his classes.

[sonjak]

Ludwig Boltzmann (20 February 1844 – 5 September 1906);
Jules Henri Poincaré (29 April 1854 – 17 July 1912)

[petergreen]

❤Thank you very much Professor and class

[joabrosenberg]

Poincare recurrences; Boltzman head appears in the room 28:00

[nurlatifahmohdnor]

570 miles = 920 kilometers


1996



Lastime I took KHB for PMR. Because we were a girls school, it was ERT. Boys school was different type of KHB.












E-ko-no-mi
Ru-mah
Tang-ga

[KipIngram]

26:21 - Well, what that tells us is that our solar system didn't just appear as an eventual result of random motion. There were organizing forces - gravity made it so all it took was a slight deviation from uniformity and from there there was a force urging the particles on toward each other. Fusion lit the sun up, etc. etc. etc. No way it was just dust wandering around. "Luck" gave us only the first nudge, and then other aspects of physics took it from there.

[atrumluminarium]

Can anyone explain what is meant by symmetry and the breaking of symmetry? I really am struggling with that concept :(

[LuukVanEgeraat]

I was looking forward to the next video in the series, thanks!

[abdurrezzakefe]

regarding the coherent wife story; if we wait way way way longer, say infinitely long, is it ok to say that some version of us in the future will have a coherent surrounding?

[PHYTOGREG]

Susskind is wrong at 26:15 min - the audience member is correct. Susskind supposes that random and independent fluctuations occur over time which determine the probability that a Boltzmann brain (A) pops into existence as (a very small) p. Then he says the 'conditional probability' (his words) that a second Boltzmann brain (B) pops into existence is vastly smaller. This is incorrect. If A and B are independent, then the conditional probability P(A|B) = P(A) = p, i.e. seeing a second brain given that you observed the first is equal to the probability of observing the first. Susskind meant to refer to the joint probability of straight-up observing two independent events (which for indpendent events is P(A)P(B)=p^2), which is vastly smaller. The audience member points this out correctly. 

[spnnar]

The idea of a body so massive that even light could not escape was first put forward by geologist John Michell, in 1783. The first person to interpret evidence and infer the presence of dark matter was Dutch astronomer Jan Oort, a pioneer in radio astronomy, in 1932.
Neither of these things are attributed to Leonard Susskind, both became interesting areas of study before he was even born.
And even string theory the thing he is most associated with started with Heisenburg in 1943, Susskind was 6.

[anklexpress]

I wonder if Neitzsche got his eternal return idea from the Poincare recurrence...I could look this up I guess but I am not

[blanamaxima]

life is like little Eddys.. like that a lot.

[nurlatifahmohdnor]

My son reminded me that lastime he asked me why the ruler is so shaped? He said that I said it is a watermelon-shape of ruler. I did not tell him it is a protractor.




Primary school boy aged 12 he was at that time.

[KipIngram]

18:25 - He's right - it DOESN'T MATTER. Say the units were Planck Time - 10^-43 seconds. So the time in seconds would then be (2^(10^30))*(10^-43). Take the base 2 log; we get 10^30 + log2(10^-43) = 10^30 - 43*log2(10) = 10^30 - 43*3.32 = 10^30 - 142.84 = pretty much 10^30. So it truly doesn't matter - the questioner just doesn't grok the vastness of 2^(10^30).