Lecture 9 | String Theory and M-Theory
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(November 23, 2010) Leonard Susskind gives a lecture on the constraints of string theory and gives a few examples that show how these work. String theory (with its close relative, M-theory) is the basis for the most ambitious theories of the physical world. It has profoundly influenced our understanding of gravity, cosmology, and particle physics. In this course we will develop the basic theoretical and mathematical ideas, including the string-theoretic origin of gravity, the theory of extra dimensions of space, the connection between strings and black holes, the "landscape" of string theory, and the holographic principle. This course was originally presented in Stanford's Continuing Studies program. Stanford University: http://www.stanford.edu/ Stanford Continuing Studies Program: http://csp.stanford.edu/ Stanford University Channel on YouTube: http://www.youtube.com/stanford
Comments
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"...it's a partial differential equation, partial differential equations are more difficult, but Partial was a very smart guy and he figured out how partial differential equations work"
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haha that look when he wants to go home but has to explain smth else 1:49:41
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This definitely doesn't djent
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This compatification thinking is sort of weird because every particle has it's own universe it seems, instead of a global compatification, unless you saw there is this sort of tendency for a dimension to close globally. What is useful here is that there are some ideas and maybe some patterns are actually witnessed somewhere, so you say there may be a string connection. Wave like observations at a macroscopic level is the happiest result of wave like mechanisms. Also it is hard to say how these strings go from being sine waves to any sort of thing and not violate the equations. Also I don't know why exactly they don't act with other strings in strange manners, like interference, and complex connection. I was really hoping to see that quantization was the result of integer like building blocks that just come together a certain way. It is strange by an arbitrary formation how atomic structure is so well defined. I don't understand how say, kinetic energy interfaces, and gets stored in an object.
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How can a string cross itself on that cylinder? (around 1:39:30) There is no height dimension to the surface of the torus/cylinder (he made a point to mention this), and the strings are literally one dimensional, so when they cross, they'd cut each other. Otherwise, how do you know which one is on top of the other?
(I realize he cuts them later when he describes winding number, but how did they cross in the first place?) -
Sometimes I just watch these lectures because of Susskind, even if I don't understand what he is talking about.
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Taking imagination to almost an intolerable level. Could be the greatest of Hawking's failures to expect the theory to explain everything although it explains nothing verifiable !?
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"Let him give the lecture, okay?"
YES, thank you. That guy just won't shut up. -
sussikind kicks ass whether u want to be bathled by his stuff when high or learning this shit for real
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Don't get me started. Well for one, E8 does contain U(1)xSU(2)xSU(3) as a subgroup. But it is huge! Its smallest irreducible rep is 248 dimensional. I suspect it is indeed more than a theory of everything: its a theory of anything.
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Actually your proper time would be just fine. Just add another minus sign to the Lorentz metric (-dTau^2 = dx^2+...dz^2-dt1^2-dt2). In fact, adding that minus sign will give you everything you need to work out the dynamics. Play with it.
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Hi, the most important thing to do is to first learn mathematics, so you can understand concepts in theoretical physics. Where in the world are you from? First I would begin to learn calculus, as a first step look up coursera and take the pre-calculus/calculus class, depending on your level. I wouldn't worry much at the moment, the easiest way to be a physicist is to go to a good university, so you need good grades in everything. Basically don't neglect your other studies. Good luck.
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I'm 14 and would like to b a theoretical physicist. If someone could write me a small plan of what to learn about first and what websites etc are useful. I have a reasonable understanding of basic physics. Thanks
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I'm 14 and would like to b a theoretical physicist. If someone could write me a small plan of what to learn about first and what websites etc are useful. Cheers
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Youtube discussions are ALWAYS a bad idea, so don't feel obligued to respond. :P But you may be right, though I don't think it is as silly a case as was implied. Everything's 'obvious' until someone finds a better 'obvious' thing, like time being a vector with different components. Proper time would be unchanged, but the time time-like coordinate would not. Not saying it's right, just not silly.
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Two dimensions of time would mean that proper time is not a valid concept. There would be 2 proper time clocks that run at different rates. Then there would be no valid rest frame concept.
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I think they kind of unfairly dismissed that guy who was talking about two time dimensions. What's so crazy about two time dimensions compared to 25 space dimensions? Maybe the second time dimension is curled up so small that only small things can move forward in it, hence vacuum fluctuations!
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Thumbs up if you understand.
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So the only geometries in which a string has a proper limit are the ones in which there are no strings? Wonderful
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Mr. Susskind knows physics very well.
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