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How hard is string theory exactly?by petergreat
Tags: string theory 
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#19
Dec710, 06:59 AM

P: 604

Oh and of course you can buy "String Theory for Dummies" at Amazon now.
(He says cynically as he secretly plans to buy it in the near future) DaveKA 


#20
Dec710, 10:23 AM

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#21
Dec810, 03:02 AM

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#22
Dec810, 03:16 AM

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There is also a big difference between first and second superstring revolution.
After the first revolution, physicists were able say: Good, now we understand the theory much better. But after the second revolution, they could rather say: Now we see that there is much more to understand than meets the eye. 


#23
Dec810, 10:56 AM

P: 119

String "Theory" is a complex topic, made more complex by that fact that is is more of a pseudoscience than proper physics  It can't be tested and doesn't make any unique predictions. Rather than try to understand string theory right now, stand back, and see if anything is actually achieved by it. Only then will it be worth the bother investigating it.
I reccomend reading Lee Smolin's "The Trouble with Physics" for a more detailed critical analysis of string theory. 


#24
Dec810, 11:05 AM

P: 117

There is enough room (by way of hithertounused, modern geometrical tools, in addition to undiscovered physics itself) in string theory to do it as "hard" as you would like to do it. While some might find generating creative physical principles hard, others find understanding and applying math tools to be hard.



#25
Dec810, 12:53 PM

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#26
Dec810, 01:24 PM

P: 119




#27
Dec810, 01:39 PM

P: 2,828

Well, thank you for your honesty and perspective. Since you mention UK institutions, I would be interested to hear the update of Penrose's opinion on string theory. There has been tremendous attention paid to the twistor formalism ever since Witten's 2003 article. This approach is essentially a revival of Smatrix method. It has provided very concrete calculation for QCD backgrounds at the LHC, and this is independent of whether string theory is realized at a fundamental level. Simply, playing with string theory (say as a toy model if you want), we discovered new methods to go beyond Feynman's perturbative calculations.
I imagine you have also heard of highT superconductors. Another example where string theory provides calculations, which makes it interesting and achieving important results, while not proving to be "fundamental" in the "popular" sense. 


#28
Dec810, 01:42 PM

P: 119

That approach, to me, does seem to be the right one. Not accepting the theory completely, but instead using its mathematics, techniques and essentials to further our current model.



#29
Dec810, 03:12 PM

Astronomy
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PF Gold
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It is also possible that interesting math will grow out of LQG. See for example: http://arxiv.org/abs/1010.1939 Feynman rules for 2complexes (spinfoams) Group field theory techniques (including the idea of a graph Hilbert space) Spin networks (an earlier idea of Penrose but developed in this context) Also the general idea of a quantum theoretical presentation of geometry, and of constructing quantum field theory not on a preestablished classical spacetime geometry but on the corresponding quantum geometrythe mathematical gains from addressing this problem (while not so widely recognized) could also be significant. 


#30
Apr311, 01:02 AM

P: 89

it is unimaginably difficult...to put it succinctly



#31
Nov2812, 09:42 AM

P: 49

It's very difficult due to the huge amount of knowledge you have to master in order to make any interesting contribution to the field and the physics is also inherently very difficult so it's difficult on both physics and math side. However , If you want to know what's string theory is all about . You can pick the book "string theory demystified " or a somewhat more advanced book " String theory and M theory" ,You can understand things in those books which gives an impression that it's not difficult at all



#32
Nov2912, 03:40 AM

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#33
Nov2912, 04:17 AM

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P: 4,590

 Because they are much more CLEVER than me and you.  Because they want to LOOK much more clever than they really are.  Because by "introduction" they actually MEAN "encyclopedic overview". By the way, as a more advanced textbook on string theory I like: M. Kaku, Introduction to Superstrings and Mtheory But for some reason, mainstream string theorists don't like this book at all. 


#34
Nov2912, 01:43 PM

P: 26

in my opinion String Theory is really a hard subject (either considering it physically sensible or just a mathematical curiosity) because the amount of material one must know to learn and persue the subject. just look at the contents of the "Quantum Fields and Strings  a Course for Mathematicians". if you want to learn the subject, my suggestions are as follows:
1) you must master (really doesn't mean that you must know everything, just the basics) the QFT especially the path integral and BRST methods for quantization of gauge theories; for this see Zee's "Quantum Field theory in a Nutshell" or Srednicki's "Quantum Field Theory" (for path integrals, Srednicki's book treated BRST also) and "Aspects of BRST Quantization" or "Quantization of Gauge Systems" (for BRST Methods); 2) you must master in 2D conformal field theory, for this the first 6 chapters of Di francesco et al "Conformal Field Theory" is sufficient; 3) you must master General Relativity, for this see Schutz "A First Course in General Relativity" or Hartels's "Gravity : an Introduction to Einstein's General Relativity"; 4) the relevent mathematics (just for start) is topology, differential geometry, complex geometry, some algebraic topology; the relevant parts of Nakahara's "Topology, Geometry and Physics" are excellent. acquaintance with group theory and representation of groups is mandatory. familiarity with differential and complex geometry of Riemann Surfaces is helpful. for Books I recommend the followings: 1) "a First Course in String Theory" by B.Zwibach (there is no need for the above mentioned prerequisite); in my opinion a "must read" to know the basics! Excellent at pedagogical style! 2) "Lectures on String Theory" or its update "Basic Concepts of String Theory" by D.Lust & S.Theisen & R.Blumenhagen(required CFT is thoroughly explained); an excellent book to start with; without exercise 4) "The Superstring Theory" by three authorities of the field M.Green, J.Schwarz and Ed.Witten; its start with dual resonance models which is not treated in any other books. in my opinion "required reading" despite of 25 years has been passed sice its publication. mathematical parts, written by Ed.Witten, are excellent; a great second book; without exercise; 3) "Introduction to Strings and Branes" by P.West, a new book with nice presentation of spinors and the role of lie algebras in string theory; a good second book; without exercise 4) "String theory in a Nutshel" by E.Kritsis, a good second book with exercise! 5) "String theory and Mtheory : an Introduction" by K&M Becker and J.Schwarz, as our friends stated this book is encyclopedic in some parts and need to be suppelmented by another math or physics book, a good second book with exercises; 6) "Vol.01  Bosonic String Theory" and "Vol.02  Superstring Theory & Beyond" by J.Polchinski, a very nice but at the same time hard book which in my opinion in "required reading". Polchinski is a master of QFT and String theory and founder of DBranes, and its insights are very helpful, a good second or third book with good exercises! 7) "DBranes" by C.Johanson: a good book on advanced topics such as Quiver gauge theories, Holographic Renormalization group and etc, a third or forth reading without exercise 8) "Gravity & Strings" by T.Ortín; an advanced text that assumes you know string theory, very good on "the stringy gravity" the two good critical books on String theory are: 1) "The Trouble with Physics" by L.Smolin; 2) "Not Even Wrong" by P.Woit if you want to know just the basics, I think that "Superstringtheory.com" and Wikipedia Articles or just Zwibach's book are sufficient! the following books are also very valuable: 1) "The Birth of String Theory" by A.Cappelli 2) "DBrane: Superstrings and New Perspective of Our World" by K.Hashimoto you must know that these are just the begining and more advanced topics such as Topological String Theory and the ones treated on the "Quantum Fields and Strings  a Course for Mathematicians", or mathematically oriented topics which are related to Field Theory and String Theory such as String topology, Quantum Cohomology and Gromov  Witten Theory and etc are much more subtle and complex! all in all, String Theory is a fascinating subject that worth learning. I always wonder why when one goes from 0D particles to 1D strings gets such a tremendous amount of new mathematics and theoretical (not necessarily physical!) ideas! Good Luck! 


#35
Nov2912, 06:46 PM

P: 14

It's as if we discovered time dilation, but without Einstein ever being born.



#36
Nov2912, 10:29 PM

P: 308

The point is you don't need to know more than 5% of string theory to do research, just like you don't need to know what a symplectic manifold is to do classical mechanics. I guess the difference is that most people can agree what the basics of CM are, but it's not yet clear for ST. Knowing all string theory is like knowing all of History. Unpractical, unnecessary, most likely impossible. 


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