Written and Illustrated by Ed Witten. (Slides 21 to 30 of 48) 21.. When the dust clears there are just 5 string theories, discovered from 1970 -84. Type I, Type IIA, Type IIB, Hetorotic E8E8 and SO/32 which differ by general properties of the strings.... raising an obvious question ....
22.. Reducing this way the number of theories has a fateful consequence . In Standard Physics the 'free motion in spacetime' can be described abstractly and doesn't really contain much information about spacetime.... (Slide 21 below) .... but the interactions depend on knowing exactly where you are. (Slide 21 below)
23.. In string theory that last part is missing so one never learns precisely what the spacetime is .... There is a new source of fuzziness that goes beyond quantum mechanical uncertainity... (Slide 23 below)
24.. Just as Quantum Mechanics puts a bound on how precisely defined can be 'the trajectory of a particle', so String Theory puts a bound on how precisely one can describe 'Spacetime'
26.. In Quantum mechanics. (Slide 26 above) is the basic scale of quantum uncertainity. In String theory, theres a new constant. (Slide 26 above) that plays an analgous role.
27.. String Theory makes three 'general' predictions.
- Gravity
- Gauge Symmetry
- Super Symmetry
and with a knowledge of the vacuum one can hope to learn more.
28.. (rather as standard quantum theory makes one general prediction - antimatter - and specific quantum field theories make more specific predictions ... )
29..
I.. Gravity means here, Einstein's Theory of General Relativity which is automatic in String Theory, while standard quantum field theory makes it impossible.
II. Gauge Symmetry is the bread and butter of the standard model of particle physics.
30.. Super Symmetry. Alongside the usual or 'Bose' dimensions of Spacetime. t = time & Space = x,y,z. There would be new, or infintismal quantum or 'Fermi' dimensions.
(Slide 30 below). Predicts new particles, oscillations in the fermi dimensions.
continues in next post .......