Skip to main content
Physics

Questions tagged [string-theory]

Ask Question

A class of theories that attempt to explain all existing particles (including force carriers) as vibrational modes of extended objects, such as the 1-dimensional fundamental string. PLEASE DO NOT USE THIS TAG for non-relativistic material strings, such as, e.g., a guitar string.

513 questions
Newest Active Bountied Unanswered
74 votes
7 answers
34k views

Is the spacetime continuous or discrete? Or better, is the 4-dimensional spacetime of general-relativity discrete or continuous? What if we consider additional dimensions like string theory ...
linello's user avatar
  • 1,297
328 votes
11 answers
54k views

I know that there's big controversy between two groups of physicists: those who support string theory (most of them, I think) and those who oppose it. One of the arguments of the second group is that ...
Albert's user avatar
  • 3,867
12 votes
1 answer
3k views

The action of a free relativistic particles can be given by $$S=\frac{1}{2}\int d\tau \left(e^{-1}(\tau)g_{\mu\nu}(X)X^\mu(\tau)X^\nu(\tau)-e(\tau)m^2\right),\tag{1.8}$$ with signature $(-,+,\ldots,+)$...
Natanael's user avatar
  • 459
42 votes
2 answers
6k views

First, I'll state some background that lead me to the question. I was thinking about quantization of space-time on and off for a long time but I never really looked into it any deeper (mainly because ...
Marek's user avatar
  • 24.1k
36 votes
10 answers
14k views

Some theories have more than 4 dimensions of spacetime. But we only observe 4 spacetime dimensions in the real world, cf. e.g. this Phys.SE post. Why are the theories (e.g. string theory) that require ...
Fakrudeen's user avatar
  • 761
50 votes
4 answers
10k views

A question in four parts. What are the main problems which supersymmetry purports to solve? What would constitute lack of evidence for SUSY at the proposed LHC energy scales (e.g. certain predicted ...
Nigel Seel's user avatar
  • 3,404
46 votes
9 answers
29k views

This is a follow-up to an intriguing question last year about tension in string theory. What are the strings in string theory composed of? I am serious. Strings made of matter are complex objects that ...
Terry Bollinger's user avatar
  • 22.4k
12 votes
3 answers
2k views

I was hoping for an answer in general terms avoiding things like holonomy, Chern classes, Kahler manifolds, fibre bundles and terms of similar ilk. Simply, what are the compelling reasons for ...
Gordon 's user avatar
  • 4,413
6 votes
1 answer
2k views

D. Tong's notes on string theory (PDF), subsection 5.1.1, feature the following in introducing the symmetries used in the Faddeev-Popov method: We have two gauge symmetries: diffeomorphisms and Weyl ...
Colliding Particles's user avatar
  • 397
35 votes
8 answers
16k views

I am in the last year of MSc. and would like to read string theory. I have the Zwiebach Book, but along with it what other advanced book can be followed, which can be a complimentary to Zwiebach. I ...
Community wiki
5 revs, 3 users 81%
DIMension10
20 votes
5 answers
30k views

String theorists say that there are many more dimensions out there, but they are too small to be detected. However, I do not understand why there are ten dimensions and not just any other number? ...
James Kujareevanich's user avatar
  • 877
8 votes
1 answer
2k views

I understand that the vibration modes of an elementary string determines the identity of its particle. When I first heard this, I visualized a stiff circular steel band-like entity vibrating with 2, 3,...
John Fistere's user avatar
  • 338
6 votes
1 answer
2k views

I) First consider the point particle $$S=m\int\sqrt{-\dot{X}^2}d\tau.$$ If you choose the static gauge $$\tau=X^0$$ and replace it in the action you get $$=m\int\sqrt{1-\dot{X}^j\dot{X}^j}d\tau.$$ ...
Anthonny's user avatar
  • 1,744
25 votes
2 answers
2k views

One way that I've seen to sort-of motivate string theory is to 'generalize' the relativistic point particle action, resulting in the Nambu-Goto action. However, once you see how to make this '...
Jonathan Gleason's user avatar
  • 8,874
9 votes
1 answer
2k views

I've read that the Polyakov action using an intrinsic metric $h_{\alpha\beta}$ $$\tag{1} S_P ~=~ -\frac{T}{2}\int d^2 \sigma \sqrt{-h}h^{\alpha\beta} \partial_{\alpha}X^{\mu}\partial_{\beta}X^{\nu} \...
Dilaton's user avatar
  • 9,821

15 30 50 per page
1
2 3 4 5
…
35