Timeline for Number of free parameters in String Theory and LQG
Current License: CC BY-SA 3.0
12 events
| when toggle format | what | by | license | comment | |
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| Oct 21, 2016 at 14:07 | comment | added | Prof. Legolasov | Neither string theory nor loop quantum gravity is capable of reproducing the standard model of elementary particles yet. So I guess it is not valid to ask if they require additional parameters to be put by hand until we know whether they explain the values of the standard model couplings naturally or not. | |
| Oct 19, 2016 at 3:43 | history | edited | Qmechanic♦ |
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| Oct 19, 2016 at 2:40 | history | edited | innisfree | CC BY-SA 3.0 |
Removed the information about edits - the edit history is there for all to see...
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| Oct 19, 2016 at 1:42 | answer | added | tparker | timeline score: 2 | |
| Oct 19, 2016 at 1:21 | history | edited | user20250 | CC BY-SA 3.0 |
added 52 characters in body; added 2 characters in body
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| Oct 19, 2016 at 1:19 | comment | added | user20250 | I see, it's a valid argument. To avoid these ambiguities and complications, I will edit to assume the dimensionality. | |
| Oct 19, 2016 at 1:08 | comment | added | tparker | Second, for dimensionalities other than 4, the field content could be totally different, as we'd need to include more or fewer renormalizable interactions, the identity $\mathfrak{so}_4 \cong \mathfrak{su}_2 \times \mathfrak{su}_2$ wouldn't allow us to consider left- and right-handed spinors separately, the gamma matrices would need to be modified, etc. | |
| Oct 19, 2016 at 1:05 | comment | added | tparker | The dimensionality of spacetime isn't really a "free parameter" as usually defined. First of all, the phrase "free parameter" usually only includes parameters than can range over continuous values, because if you include discrete parameters, it's ambiguous what counts. You need to specify all the representations that the various matter fields live it, which would require at least 18 more (discrete) parameters. And would the gauge group count as another parameter? | |
| Oct 19, 2016 at 0:36 | history | edited | user20250 | CC BY-SA 3.0 |
added 61 characters in body
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| Oct 19, 2016 at 0:34 | comment | added | user20250 | Oh yes, that's right, I'll edit it. | |
| Oct 19, 2016 at 0:33 | comment | added | innisfree | Actually, $\hbar$ and $M_P$ (i.e. $G$) just specify a system of units. They are not really physical parameters, you can work in a system of units where they are both 1. They don't need to me included here. | |
| Oct 19, 2016 at 0:30 | history | asked | user20250 | CC BY-SA 3.0 |