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27. Natural Reality / B. Modern Physics / 5. Unified Models / b. String theory

[vibrating strings explain all fields and particles]

8 ideas
String theory only has one free parameter (tension) - unlike the standard model with 19 [Martin,BR]
     Full Idea: Unlike the standard model, with its 19 free parameters (including the masses of quarks, coupling constants and mixing angles), string theories have a single free paramater: the string tension.
     From: Brian R. Martin (Particle Physics [2011], 10)
     A reaction: This must be one feature in favour of string theory, despite its problems.
String theory needs at least 10 space-time dimensions [New Sci.]
     Full Idea: String theory needs at least 10 space-time dimensions to be mathematically consistent.
     From: New Scientist writers (New Scientist articles [2013], 2013.06.15)
     A reaction: Apparently because of 'Ads/CFT', it may be possible to swap this situation for a more tractable 4-dimensional version.
It is impossible for find a model of actuality among the innumerable models in string theory [New Sci.]
     Full Idea: String theory has more than 10-to-the-500th solutions, each describing a different sort of universe, so it is nigh-on impossible to find the one solution that corresponds to our geometrically flat, expanding space-time full of particles.
     From: New Scientist writers (New Scientist articles [2013], 2015.11.07)
In string theory space-time has a grainy indivisible substructure [New Sci.]
     Full Idea: String theory suggests that space-time has a grainy substructure - you can't keep chopping it indefinitely into smaller and smaller pieces.
     From: New Scientist writers (New Scientist articles [2013], 2015.11.07)
     A reaction: Presumably the proposal is that strings are the true 'atoms'.
String theory might be tested by colliding strings to make bigger 'stringballs' [New Sci.]
     Full Idea: A future accelerator might create 'stringballs', when two strings slam into one another and, rather than combining to form a stretched string, make a tangled ball. Finding them would prove string theory.
     From: New Scientist writers (Why the Universe Exists [2017], 08)
     A reaction: This is the only possible test for string theory which I have seen suggested. How do you 'slam strings together'?
String theory offers a quantum theory of gravity, by describing the graviton [New Sci.]
     Full Idea: String theory works as a quantum theory of gravity because string vibrations can describe gravitons, the hypothetical carriers of the gravitational force.
     From: New Scientist writers (Why the Universe Exists [2017], 09)
     A reaction: Presumably the main aim of a quantum theory of gravity is to include gravitons within particle theory. This idea has to be a main attraction of string theory. Compare Idea 21166.
String theory is now part of 11-dimensional M-Theory, involving p-branes [New Sci.]
     Full Idea: String theory has now been incorporated into Ed Witten's M-Theory, which is a mathematical framework that lives in 11-dimensional space-time, involving higher-dimensional objects called p-branes, of which strings are a special case.
     From: New Scientist writers (Why the Universe Exists [2017], 09)
Supersymmetric string theory can be expressed using loop quantum gravity [New Sci.]
     Full Idea: String theory, together with its supersymmetric particles, has recently been rewritten in the space-time described by loop quantum gravity (which says that space-time ust be made from finite chunks).
     From: New Scientist writers (Why the Universe Exists [2017], 09)