Timeline for What is tension in string theory?
Current License: CC BY-SA 2.5
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| Sep 28, 2021 at 4:06 | comment | added | Luboš Motl | Constant. Well, the string may often be imagined as a wrapped membrane and the tension is proportional to the wrapped circumference. In that case, the tension could be variable but usually a function of spacetime, not world sheet, coordinates. | |
| Sep 27, 2021 at 3:11 | comment | added | HelloGoodbye | If $T$ a constant, or does it depend on $\tau$ and/or $\sigma$? | |
| Feb 8, 2011 at 7:23 | history | edited | Luboš Motl | CC BY-SA 2.5 |
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| Feb 3, 2011 at 8:12 | history | edited | Luboš Motl | CC BY-SA 2.5 |
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| Jan 30, 2011 at 9:02 | comment | added | Luboš Motl | Dear @Georg, right, the closed strings are not attached anywhere. That's why they shrink to small size. The same is actually true even for open strings that are attached to 2 objects - called D-branes - by their endpoints. Unless they're attached to two different D-branes that are also separated in space, open strings shrink to minimum size allowed by quantum mechanics, too. The size is called the string length and is tiny. Smaller size is not allowed by the uncertainty principle - a more precise localization of the string would raise the kinetic energy. | |
| Jan 20, 2011 at 12:30 | comment | added | Georg | @ Lubos Hmm, strings very like piano strings with variable length, but where are the hooks the string is fastened to? Do this strings have some "stiffness"? (ie, can they vibrate like a rod, transversally or longitudinally? Excuse the maybe laymans questions. | |
| Jan 19, 2011 at 16:18 | comment | added | user346 | Nice answer @Lubos. Stringy matter naturally has negative pressure, then? That's remarkable. I was aware of the standard example of a scalar field, as in the case of a inflaton or dark-energy models, where the field has a negative equation of state. I've mentioned previously that I'm starting to seriously study strings and this is one of the best surprises in that regard. Naively this fact would seem to have obvious significance for the cosmological constant problem. Again, an idea that I'm sure has already been studied to death but I'm just learning about! | |
| Jan 19, 2011 at 16:00 | comment | added | user1355 | Thanks Lubos. It certainly helped. What I have understood from your post is, the best way to think of "string tension" is to think it in terms of its action per unit of proper area of the string world sheet. Thanks. | |
| Jan 19, 2011 at 15:03 | history | answered | Luboš Motl | CC BY-SA 2.5 |